Scanned Image - American Radio History

INSIDE CHANNEL 7'S NEW TELEPOOLS GAME
.
Australia's
Top Selling Electronics Magazine
NDD
WITH
7AUGUST 1990 Aust* $4.50 NZ $5.95sT
EXCLUSIVE:
SONY'S NEW
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SPECIAL FEATURE ON LOUDSPEAKER TECHNOLOGY
PROJECTS TO BUILD: DIGITAL STOPWATCH/LAP TIMER,
REPROGRAMMABLE LOCK, TTL/CMOS LOGIC PROBE
i
312966 12363
Registered by Australia Post
-
Publication No. NBP 0240
Our national hybrids manager
would love to tell you about the tricky
problems we've solved for others.
Aerospace, automotive, datacoms,
defence, entertainment, general
industrial, health, mobile radio,
security, telecommunications,
wh i tegoods.
j28nP9F
There are dozens of Australian
customers in these areas we can't tell you
about because custom-made is, well, made
just for that customer. The intellectual
property wrapped up in their special
hybrid electronic package is theirs. Each
customer has available the advantage of
three special savings for their project:
space savings of hybrids hassle -free
savings because of the inherent reliability
(85% Rll/85°C/10(0 hrs) of a purpose
designed electronics package and money
savings because Philips' facilities and
experience can save them expensive
production line investment that would
have been unavoidable.
We'd like to say more but
modesty prevents us. Call Richard Thode
or Phil Tracy on (02)4393322, or
John Simpson on (08) 348 5200 for a
confidential chat about an Australian -made
hybrid or Custom IC solution for you.
/
I
United Notions
2336
Philips Components
PHILIPS
READER INFO NO. 1
PHILIPS
Volume 52, No.8
AUSTRALIA'S LARGEST SELLING ELECTRONICS MAGAZINE
Designing 7's new
Telepools game
VYU('
'
-
August 1990
ESTABLISHED IN 1922
Features
14
32
58
170
174
PHILIPPINE TRADE MISSION VISITS SYDNEY Electronics firms
WHEN I THINK BACK... Major Edwin Armstrong -2
THE EASY WAY INTO COMPUTERS Using 'pre -loved' micros
FAREFORWARD VOYAGER To the end of the solar system...
CAD SOFTWARE REVIEW: Protel's Schematic V3.3
a
Entertainment Electronics
6
10
MIL
f"---
Next month the Seven network
launches its new
'Telepools'
game. Here's how its impressive
computer -driven display system
was created, explained by its designer. (Page 10)
L
This month's ETI is again in the
centre of the book, starting
opposite page 70. Highlights
include a look at CD-ROM
technology, by Geoff Bains;
Louis Challis's report on KEF's
new
'UNI-Q' speaker; Les
Cardilini's look at Hitachi's
laptop VCR; and a feature by
Jim Rowe on current speaker
technology.
On the cover
Sony's new 'Data Discman'
handheld CD-ROM player has
just been released in Japan, and
should arrive here soon. It's basically the first true electronic book
see page 20. (Picture courtesy
Sony Australia.)
-
WHAT'S NEW IN HOME ELECTRONICS Latest audio, video products
INSIDE 7'S NEW TELEPOOLS TV GAME Technical preview
Projects and Technical
24
36
46
50
110
112
120
128
138
152
SIMPLE METHOD OF TIMING CAMERA SHUTTERS Cheap, too
BASIC ELECTRONICS
Capacitors and their uses
THE SERVICEMAN Enough! Enough! He cried and so on
THE 'ULTIMATE' SPEAKER LEADS? Could be...
CIRCUIT & DESIGN IDEAS Car alarm protector, soil heater thermostat
FLEXIBLE LOW COST CMOS/TTL LOGIC PROBE Easy to build
IMPROVED COMBINATION LOCK Easily reprogrammable
SSTV TRANSMIT SCANCONVERTER
2 Building & testing it
DIGITAL STOPWATCH WITH LAP TIMING Compact, flexible
VINTAGE RADIO Loop aerials
-6
-
-
News and Comment
4
5
20
44
62
66
146
155
156
164
166
LETTERS TO THE EDITOR Fluoro wiring, science and youth
EDITORIAL VIEWPOINT Lessons to be learned from a developing country
NEWS HIGHLIGHTS Sony's new 'Data Discman' electronic book
SHORTWAVE LISTENING Arthur Cushen's column returns to EA!
FORUM How much safety do ELCB's provide?
SPECTRUM Communications news and comment
NEW PRODUCTS Super large instrument case, MIDI controllers
AMATEUR RADIO NEWS More Australian, world records
INFORMATION CENTRE Questions answered, puzzlers etc.
SILICON VALLEY NEWSLETTER Motorola/IBM radio data network
SOLID STATE UPDATE 3A switching regulator chip, wideband MUX
Departments
68
160
160
161
178
178
158
BOOK REVIEWS
EA CROSSWORD PUZZLE
50 AND 25 YEARS AGO
MARKETPLACE
DIRECTORY OF SUPPLIERS
ADVERTISING INDEX
NOTES AND ERRATA
ELECTRONICS Australia, August 1990
3
MANAGING EDITOR
Jamieson Rowe, B.A., B.Sc.,
SMIREE, VK2ZLO
NEWS EDITOR
Winifred Vincent, MSEE, MS.Phys
TECHNICAL EDITOR
Peter Phillips, B.Ed., Dip.Ed., ECC
PRODUCTION CO-ORDINATOR
Milli Godden
EDITORIAL STAFF
Rob Evans, CET (RMIT)
SECRETARY
Karen Muggleton
ADVERTISING MANAGER
Selwyn Sayers
CONTRIBUTORS
Neville Williams, FIREE, VK2XV
Jim Lawler, MTETIA
DRAFTING
Karen Rowlands
GRAPHICS DESIGNER
Clive Davis
ART PRODUCTION
Alana Horak, Ray Eirth, Michael Riley
PRODUCTION
Tracy Douglas
ADVERTISING PRODUCTION
Brett Baker, Inga Tettmann
CIRCULATION MANAGER
Michael Prior
DISTRIBUTION MANAGER
Helen Petersen
PUBLISHER
Michael Hannan
HEAD OFFICE,
EDITORIAL & ADVERTISING
LETTERS TO
THE EDITOR
Fluoro wiring
Along with
180 Bourke Road, Alexandria, NSW 2015
P.O. Box 227, Waterloo 2017.
Phone: (02) 693 6620
Fax number: (02) 693 6613
For Reader Services, phone 693 6620
For Subscription Enquiries, phone 693 9517
INTERSTATE ADVERTISING OFFICES
Melbourne: 221a Bay Street, Port Melbourne,
Vic 3207. Phone: (03) 646 3111,
Fax No: (03) 646 5494, Nikki Roche
Brisbane: 26 Chermside Street, Newstead,
Old 4006. Phone: (07) 854 1119,
Fax No: (07) 252 3692, Bernie Summers
Adelaide: 98 Jervois Street, Torrensville, SA
5031. Phone: (08) 352 8666,
Fax No: (08) 352 6033, Mike Mullins
Perth: 118 Forrest Street, Cottesloe, WA
6011. Phone: (09) 385 3332,
Fax (09) 385 3700 Estelle de San Miguel
New Zealand: 63-73 View Road, Auckland,
New Zealand. Phone: (09) 443 0954,
Fax No: (09) 443 1326, Gordon Marr
United Kingdom: John Fairfax & Sons (Ault)
Ltd. 12 Norwich Street, London, EC4A IBH.
Phone: (01) 353 9321, Fax: (09) 593 0348
ELECTRONICS AUSTRALIA is published
monthly by Federal Publishing Company Pty.
Ltd. Incorporated in NSW, 180 Bourke Road,
Alexandria, NSW 2015.
Copyright © 1989 by the Federal Publishing
Company Pty Ltd, Sydney. All rights reserved.
No part of this publication may be reproduced
in any way without written permission from the
Publisher or Managing Editor.
Typeset and printed by Hannanprint, 140
Bourke Road, Alexandria, NSW for the
Federal Publishing Company Pty Ltd.
Distributed by Newsagents Direct Distribution
Pty Ltd, 150 Bourke Road, Alexandria
NSW 2015, (02) 693 4141.
ISSN 0313-0150
'Recommended and maximum Australian
retail price only.
Parkinson's
ELECTRONICS Australia, August 1990
I
"Never check anything, you will find it's
wrong."
In your otherwise informative article
on page 162 of January 1990, 'Understanding Fluorescent Lamps', the illustration Fig.1, falls into the old trap of
inserting the ballast in series with the
supply active from the wall switch instead of the neutral conductor as illustrated by the manufacturer on the unit
of the same page.
Over a period of some 40 years, I
have pointed out this discrepancy to
many qualified electricians, without lasting effect. I believe this is caused by a
misguided idea that the limiting device
should be in the supply active.
While I have never queried the manufacturers, I assume connection in the
neutral is to reduce insulation stress and
may also reduce radio interference. A
few words from a manufacturer might
clear up all our misconceptions.
W.B. Weiley, VK2AZW,
Boat Harbour, NSW.
Science and youth
The problem of a lack of bright
young people going into science and
electronics is indeed a worry, as you so
wisely point out in your April editorial.
The government must shoulder a lot of
the blame and show more responsible
leadership. The politicians are directly
responsible for the exclusion of the far
sighted, clear visionary Barry Jones,
from the cabinet. This is a tragedy,
whatever the colour of our political beliefs. Governments claim (mostly correctly) they only reflect community attitude, but they do have a responsibility
to show more foresight and initiative on
this issue.
What can we expect them to do?
Three suggestions:
1. A more positive attitude towards encouraging private enterprise (like the
now being deSarich engine
veloped overseas, or the airport
radar system which met a similar
-
2.
4
Murphy's,
am developing a growing
confidence in Weiley's law. That is,
and Peter's,
fate);
Realistic funding of the CSIRO
so
it
can function as it did years ago.
science
and technology
3. Provide
education scholarships for the intellectually gifted. There is a lot of well
meaning but misdirected funding for
the slower learners in our schools.
Quite a lot is known about the reasons for their lack of progress but little about what to do about it. The
other end of the spectrum would respond much more positively to funding. Something is being done in this
area, but it is not widespread. Many
bright students are bored stiff with
an unchallenging curriculum and at
least, mark time for a few years. At
worst they are completely turned off.
This is a resource that Australia
must nurture. Unfortunately, to
spend public monies on bright students is likely to appear elitist and so
be politically unpopular.
Item 3 above, is a hobby horse of
mine, inspired by 30 plus years of (I
think successful) mathematics teaching
of 10 to 18 year olds. To give an uplift
in student education, more funding is
needed for good maths, science and
technology teachers. The Federal Government has moved in this direction by
provision of Higher Education Commonwealth Scholarships. These were,
among other things, intended to provide
scholarships to encourage teachers to
switch from 'overcrowded' areas such as
the Social Sciences, ,to Maths, etc.,
teaching. It sounds good, but has not
happened in practice yet. Most HECS
scholarships are going to provide higher
degrees such as Master of Education.
This is commendable in itself, although
I cannot see how it helps the current
nor, at
teach shortage in Maths, etc.
the base line, whether many students
will benefit.
Your magazine is doing its fair share
of alerting the community. The problem
is that you are preaching to the converted. It is up to all of us seriously interested and concerned about the situation
to stir up a wider community interest.
For a start we should write to and stir
our politicians. Passively sitting back
and blaming 'them' will achieve nix. We
must convince our representatives that
there are votes as well as the future of
our lovely country at stake.
-
Also we must somehow sensitise the
whole community to the problem and
try to shake off the lethargic `Ocker/
knocker' image that seems to exist
about science and technology. The
greenies have done it for conservation,
so why cannot we achieve the same effect for technology? How about it, EA
readers?
John Coulson,
EDITORIAL
VIEWPOINT
Dilston, Tas.
Valve amplifier
I read with interest the article on the
`Series 500 Integrated Amp', (What's
New in Home Electronics, May 1990),
and I'm very happy to see that our forefathers are still gainfully employed!
I must admit the Tribrid critter does
look `simply stunning', but as far as the
`supersonic performance'
perhaps if a
little shelf was added as a teapot warmer, you could enhance its spec's.
Enough of the sarcasm, I'm sure this
unit will appeal to many groups. As ergonomics and compatibility play such a
big role in marketing today, may I suggest an advert in a popular Amateur
Radio magazine...
Finally, I would like to thank Audio
Products for brightening up my dull
day. It is great to see that some companies still have a sense of humour!
Graeme Barber,
Albury, NSW.
-
Shortwave listening
I am 13 years old and very interested
in electronics and its applications, but
especially in radio and communications.
I would be very happy if EA could
start a new department which will include new stations received on the
shortwave bands (broadcast and amateur), articles describing stations and
their transmitting frequencies and even
radio and communications projects
(starting, perhaps, with an easy to build
all -wave receiver which can resolve both
AM and SSB).
I think Electronics Australia is very
interesting and informative, and it has
helped me to learn most of what I know
about electronics.
I'm quite sure that other readers will
also be interested in the addition of this
department to the magazine.
Ron Steinfeld,
Glen Waverley, Vic.
Comment: As you've probably noticed
already, Ron, your wish has been granted. As part of the merger with ET/,
we're again running Arthur Cushen's excellent column on shortwave listening.
We hope you enjoy it.
Lessons to be learned
from a developing country
A few weeks ago I had the opportunity to meet the chief executives of five
leading electronics manufacturing firms from the Philippines, who were visiting Sydney as a Trade Mission organised by the Philippines' Department of
Trade and Industry, and sponsored by the Australian Government through
the ASEAN -Australia Economic Co-operation Program. Details of the five
gentlemen concerned and the companies they run are given in this month's
story, beginning on page 14.
It was very interesting to meet with these executives and to hear of the successful growth of both their own firms, and the Philippines' electronics manufacturing industry as a whole. Afterwards I also found it most informative to
read through the literature they brought with them, describing the ways in
which the Government of the Philippines has encouraged (and is still encourby both local entrepreneurs
aging) the growth of electronics manufacturing
and foreign investors.
I couldn't help being struck by the contrasts between what has happened
and is still happening in the Philippines, a country that is developing in both
a country that has supposedly reached
senses of the word, and in Australia
`developed' status.
Through its `Omnibus Investment Code', the Government of the Philippines has provided a wide range of incentives for investment in the country's
manufacturing industry. These include income tax holidays, tax credits on the
purchase of locally -manufactured capital equipment, tax and duty exemptions
on capital equipment imported for manufacture, simplification of Customs
procedures, and the creation of export manufacturing zones for fully foreign owned bonded manufacturing.
The nett result of all of these incentives is that this `developing' country
now has a thriving electronics manufacturing industry, with annual exports
averaging well over US$1 billion for the last eight years.
Contrast this with the situation here, where one way and another there has
apart
been very little real incentive for investment in local manufacturing
from the Australian Government's `Partnerships for Development Program',
which is essentially a tarted-up offsets scheme to force the multinationals to
make at least a token investment in local manufacture. We have very few of
the kind of incentives that are available in the Philippines, and no real commitment by our publicly -owned authorities to buy locally made products in
preference to imports. In many cases our import duties on both capital equipment and components for manufacture are actually higher than those on complete imported products.
It's not surprising that our electronics manufacturing industry in particular
seems much less bouyant than that of the Philippines. Non-PDP investment is
very low indeed, and probably falling, while even with the figures for PDP
firms included I suspect we're still likely to be trailing well behind them in
terms of exports.
Sobering, isn't it, that our `developing' neighbours are leaving us behind. It
sounds as if we need to get stuck back into `developing' again ourselves...
-
-
-
Nov
Revt.
. S Australia, August 1990
5
What's New In
HOME ELECTRONICS
'-'
Akai VCRs offer many
speeds, languages
Akai has introduced two further VCR
models at the lower price entry points
of $599 and $499: the VS -465 and VS425 respectively.
Both models have picture quality,
while the VS -465 offers the DX3 head
system which AKAI claims to provide
clear pictures even in slow, still, and
frame by frame operation.
Up to 60 station pre-sets are provided, with the pre -tuning of stations 2,
7, 9 and 10. Further pre-set tuning or
custom tuning to other desired frequencies is easily accomplished.
A total of 14 variable playback speeds
Smallest VHS -C
camcorder
Panasonic has launched the NV -SI,
the smallest VHS -C camcorder weighing
approximately 750grams and ergonomically designed to fit comfortably in the
palm of a hand.
The NV -S1 movie camera is not only
compact and easy to handle, but includes many innovative features
in -
-
6
ELECTRONICS Australia, August 1990
'
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are offered on the VS -465 and nine
speeds on the VS -425. Akai uses its
proprietary Interactive Monitor System
on both models. This displays the programming information clearly on the
eluding EIS (electronic image stabiliser), which prevents picture jitter during
shooting. EIS quickly detects and corrects displacement of the picture caused
by unstable hand movement.
The camera's advanced auto focus
system takes one second to judge which
way the lens should move to catch action clearly and another for the movement of the lens. Focusing time has thus
been shortened by a full second over
conventional systems. If someone passes
in front of the camera during shotting,
the camera is able to quickly judge
whether he or she is the new subject, or
merely a passer-by who should not be
focused.
Sound, although miniaturised is from
an improved two-way unidirecitonal system improving sound quality and isolating annoying external noises often
picked up by conventional microphones.
Useful functions provided on the NV SI including a still/strobe function,
snapshot recording function, digital auto
tracking and digital title memory.
The NV -SI uses the popular VHS
tape system in its compact 'C' type cartridge format, which can be played in
any VHS video tape recorder.
The recommended retail price will be
approximately $2500.
For further information contact Panasonic Australia, 95-99 Epping Road,
North Ryde 2113 or phone (02)
886 0200.
®
...
..
ALU
ü1C3...
screen, in bar -graph form. The programming instructions can be selected in
any of eight languages
English,
French, German, Spanish, Italian,
Dutch, Swedish and Finnish.
-
rZZ:Mil/
New Sony
power amplifier
To complement its recently released
TA -E 1000ESD digital signal preamp,
Sony has also released a new power amplifier, the TA-N55ES.
The new TA-N55ES features high
current delivery and high power output.
FTC rates four ohm low impedance
drive capability, spontaneous twin -drive
supply design, G -chassis and discrete
output devices ensure reliability and
sound quality no matter what speaker is
used.
As the cosmetic match to the new
TA-E1000ESD, the TA-N55ES can be
used in stereo and mono mode to power
front channels and additional units can
be used to power rear and centre channels, keeping a balanced configuration.
It is priced at $899.
For further information contact Sony
Australia, 33-39 Talavera Road, North
Ryde 2113 or phone (02) 887 6666.
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rera
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It
,
Audiophile
ar
ktb
D -to -A
converter
Digilog from Musical Fidelity is
claimed to be one of the first truly affordable stand-alone digital -to -analog
converters aimed at the audiophile market, and is said to offer a new standard
of digital replay fidelity.
Used with any CD player or DAT
machine which has a digital output, the
Digilog is said to upgrade performance
to the highest level possible.
Digilog accepts two inputs of the
coaxial line format and one in optic
fibre format, and a digital output is also
available for DAT monitoring. Extensive use has been made of new technologies in circuit design and layout and
in the selection of components.
For further information,
contact
Audio Products, 8 Tengah Crescent,
Mona
Vale
2103
or
phone
(02)
997 4666.
L.
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Breathing monitor
for babies
`Life Alert' is an intelligent baby
monitoring system that allows parents
and babies to get a good worry -free
night's sleep. Developed with leading
paediatric researchers, it brings the
high-tech safety of modern medical facilities into a simple easy to use home
monitoring system.
At the heart of the system is a moisture proof mattress which is fitted with
respiratory motion sensors and pulsation
unit. The sensory mattress monitors the
baby's breathing motion anywhere on
the mattress surface. No awkward electrodes, wires or probes restrict the
baby, which is completely isolated from
all electrical components.
Using research carried out by the
University of New England, dealing
with the effects of pulsation in the treatment of asthma and other respiratory
problems, the Life Alert Mattress has
been designed to incorporate the option
of providing physical breathing stimulus
in the event of an emergency. These
studies apparently have resulted in the
conclusion that pulsations create an involuntary response in the muscles to
initiate chest movement.
For further information contact Axiomedix, 72 Helen Street, Sefton 2162
or phone (02) 644 5822.
Affordable VCR from Tandy
Tandy's model VR-2200 is a convenient and affordable VCR. Its special
feature is the picture -in -picture display,
where two programs can be watched simultaneously
one without sound
on an inset sub -screen. Program choice
is made easier with multi -TV programme scan, where four still pictures
are displayed at the one time, until the
desired program is chosen.
The VR-2200 includes the full range
of normal VCR functions such as fast
forward, reverse, record, pause etc. An
infra -red multifunctional remote -control
has LCD display with clock, date and
on -screen prompts.
Suitable for instruction videos, the
-
-
Lesson Repeat function allows a section
of tape to be repeated up to five times.
The Index/Go To Search function
records an ID number at the beginning
of each program and searches for it
when required.
With the Quick Start Recording timer
you can quickly start recording a program and then set its finish time, so
there's no problem with missing the
start of a show. A built-in one year, six event timer means you can record easily
when not home.
The VR-2200 is priced at $1199.
For further information contact your
nearest Tandy store or phone (02)
675 1222.
ELECTRONICS Australia, August 1990
7
If
HOME ELECTRONICS
4.11
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Twin compact disc and cassette system
Locally made
electrostatic loudspeaker
Sharp's ZCD830 is a portable hifi system which features twin compact disc
players and a twin cassette system. Now
you can program the tracks on two of
your favourite CDs to play without interruption for up to two hours, in whatever order you decide.
Designed as a portable shelf hifi, it is
powered by batteries and normal household electricity supply, allowing it to be
played both indoors and outdoors. Two
12cm free edge woofers and an 8cm
super woofer are built in, with optional
twin 8cm full range surround speakers
also available.
The ZCD830's twin CD players have
an automatic programmable music selector (APMS), plus an automatic pro-
The Australian -made TSP2400 has an
electrostatic cell with walnut emperite
side panels 2100 x 415 x 100mm deep. It
has the power supply built into the base
of the cell, running at 4kV using a
mains isolating transformer and voltage
amplifier network. The minimum audio
drive power required is 20W, with a
maximum of 250W.
The speaker membrane is made of
high tech plastic film using metal alloy
formula coating. This is a departure
from conventional electrostatic technology, preventing migration of the conductive coating. It has frequency response from 35Hz to 22kHz in a normal
lounge room environment. As there is
no enclosure as such, the low end response is determined by the dimensions
of the listening room and its acoustics.
The TSP2400 has a horizontal dispersion of 35° to give a wide angle of
image, and in the vertical direction it is
a line source. Rear radiation is equal to
front radiation, giving a realistic ambience.
The quoted price for the TSP2400 system is $12,000. For further information
contact TSP Technology, 4/11 Clarice
Road, Box Hill 3128 or phone (03)
899 6755.
8
ELECTRONICS Australia, August 1990
gram locate device (APLD) and automatic program search system (APSS)
enabling you to nominate your own selection of tracks to play in the order
you prefer, or immediately access any
tracks of your choice. You can operate
APMS, APLD and APSS for both CDs
via the remote control.
Other features of the unit include
X -bass boost, a four -band graphic
equaliser and four -band spectrum analyser, and volume indicator. The ZCD830
has a recommended retail price of less
than $1100.
For further information contact Sharp
Hunting Corporation of Australia,
wood Driver, Blacktown 2148 or phone
1
(02) 831 9350.
Super -VHS time lapse recorder
Almost three weeks of high resolution, time lapse recording is now possible using Panasonic's new AG -6720
S-VHS/VHS time-lapse video cassette
recorder.
This versatile VCR, distributed locally
by GEC Video Systems, records up to
480 hours of time lapse images and is
ideal as the core of a CCTV surveillance system for observation and task or
process analysis. The robust mechanical
construction of the AG -6720 and the
professional picture quality of the
Super -VHS format provides excellent
time-lapse images without flashes,
glitches or picture instability.
For trigger recording, a simple rear -
panel connection accepts a contact closure -type trigger, to enable VCR activation from an alarm circuit command.
Very long time lapse recording projects
can also be easily controlled via the internal or an external timer.
Horizontal resolution of more than
400 lines in both colour and black -and white is a feature of the S -VHS format.
S -VHS also involves the use of a higher
frequency FM radio signal compared to
conventional VHS, to produce extremely sharp, low noise pictures.
For further information contact GEC
Video Systems Division, 2 Giffnock
Avenue, North Ryde 2113 or phone
(02) 887 6222.
Yamaha brings you the
most innovative
entertainment technology
since moving pictures...
Moving sound.
Prepare yourself for a very special audio and video experience.
Man Left
Effects
With Yamaha's innovative Digital Sound Field Processor technology, you can
recreate the excitement
of actual live performance
fr
r'
4
e
Effects
Mom Right
f
venues and cinema sound, right in your
own living room.
Centre Speaker
Digital Sound Field Processing precisely recreates the special ambiance of these
environments, for
a
breathtaking listening experience.
At the touch of
a button you can have the acoustic characteristics
concert hall,
a
of
a European
Jazz club, an open air
Rock venue, a Disco, a Church or even an
Opera house.
e
When watching video, just select
_
.
ra,,
Joo
DOLBY' PRO-LOGIC SURROUND to
4C"t<t
recreate the magic
of
L
Effects
Effects
Multi -dimensional sound imaging
created with a 7 -speaker DSP-
the cinema.
For example, when a movie shows Dolby Pro Logic surround
a gun being
rt,E1,
system.
fired. you'll hear the bullet ricochet around the
room. When a plane prepares to land, you'll hear it soar over
Yamaha's exciting `Moving Sound' system: The DSP-A700
amplifier and it's companion AVS-700 selector, centre speaker, you from behind and touchdown at the front of the room main speakers and the smaller effects speakers.
fully managed by
a
that's just how life -like this system sounds! All functions are
learning remote control which completely
integrates and operates your TV, video and audio system.
To experience the excitement of `MOVING SOUND' and to
YAMfind
out just how easy this system is to operate and install in your
living room,
see
your local YAMAHA HI-FI Specialist now.
FIVE YEAR WARRANTY
'Dolby Pro Logic Surround
is
a trademark of Dolby Laboratories
READER INFO NO. 2
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The Telepools game in operation at Channel 7's studios, with compere Jimmy Hannan. As you can see, the
to look like a large Pools coupon, and is quite impressive.
set
is
built
Inside 7's new
'Telepools' TV -game
Next month, a new gameshow should be going to air on the Seven TV network across Australia. `Telepools' is a fast-moving 3 minute segment which gives players of the Australian Soccer
Pools a second chance to win prizes and cash. Although the game appears simple, a lot of
technology has gone into the studio set you see on your TV. The electronic system was designed and built by Right Hemisphere, a design company located in the Blue Mountains west of
Sydney. In this article, Right Hemisphere's MD Peter Vogel describes the special problems that
this project presented and how they were overcome.
The Telepools game is the brainchild
of Barry Newman, Creative Director of
Kevin Jacobsen Marketing. The objective was to provide a TV gameshow
linked to the well-known `Pools'; an
Australia -wide 'soft gambling' game
which until now, has not had a very
high television profile. Telepools allows
Pools players who were not lucky
enough to pick the winning numbers a
second chance to win prizes and cash.
10
The basic idea is that a contestant plays
from their home via the telephone. The
show is hosted by Jimmy Hannan.
Behind Jimmy is a huge board laid
out like a Pools coupon, with the numbers 1-38 in a larger -than -life array.
Several times per second one of these
numbers is illuminated, the sequence
being random. To play the game, the
player nominates six numbers, from one
to thirty-eight. He or she then says the
ELECTRONICS Australia, August 1990
word `pools' into their phone, which
causes the number illuminated at that
moment to be `locked off'. If that number is one of the nominated numbers,
the corresponding prize is theirs. This is
repeated six times, so there is a good
chance of winning something. To make
the rewards greater still, each time the.
player locks off a number, a cash prize
is given as well.
The whole game is over in just three
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Above shows the rear of the
electro -mechanical displays, each
driven by dual controller cards (one
for backup). Above right shows Peter
Vogel installing one of the 100 -odd
cards, while at right is the overall
system block diagram.
minutes, in which time that week's official Pools game results are revealed and
the home player can win up to six prizes
plus cash.
GAMEBOARD
LAMP
DRIVERS
POWER
SUPPLIES
5KVA
Serial/parallel
Interlaces
7-SEGMENT
DRIVERS
PHONE LINE
INPUT_oil
AUDIO INPUT
PROCESSOR
SOUND EFFECTS
STORE (EPROM)
AUDIO TO
DESK
The mission
It took a number of years for the
Telepools concept to become a commercial reality, but once contracts had been
signed, things moved quickly. Because
of the need to construct the studio set
before a pilot programme could be recorded, there was considerable urgency
to get the system operational as quickly
possible.
Right Hemisphere was briefed early
in 1990, and a timeframe of just eight
weeks was nominated for design and
construction of the electronics required.
as
construction company,
Telsets, was commissioned to produce
the physical set into which the electronics would be installed.
Meanwhile,
CONTROL
PANEL
RS -232 TO
CURRENT LOOP
PC
=Intercomputer
comms
BACKUP
CONTROL
PANEL
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To backup gameboard systems
PC
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To backup audio systems
a set
Basic strategy
Although the game is fairly straightforward to play, the control system required is far from trivial. The game board contains over 300 lamps, as well
as some 30 seven -segment displays, each
requiring individual computer control.
The game also requires audio from the
telephone line to be processed and used
as a trigger, and a number of different
sound effects to be generated as the
game progresses. A complex graphics
display was also required, to mimic the
action of the gameboard so that the
operator can check that all is operating
properly.
The basic strategy adopted was to use
a personal computer with VGA graphics, connected to specialised interfaces
for controlling the lamps, displays, and
audio input/output circuitry.
The gameboard is located at some distance from the computer, so in the interests of eliminating the risk of earth
loops and noise problems, an optically isolated serial current loop was chosen
as the best means of interconnection.
This was also a wise safety measure,
since the computer needed to be interfaced to many kilowatts' worth of 240
volt lamps.
Failsafe system
The prime requirement for the system
was that it be highly reliable and failsafe. Because the game is played with a
home contestant 'on line', there is no
scope for going back and re -taking in
a player
case of equipment failure
would not be very happy to be told,
-
"Sorry, you didn't really win that car, it
was a computer fault". The design had
to ensure that no matter what compo-
ELECTRONICS Australia, August 1990
11
.
Telepools game
nent fails, the show goes on.
To achieve this, a strategy of 100%
redundancy was adopted; that is, the
entire system is duplicated and both run
in tandem. In case of a failure, ranging
from a blown lightbulb to a computer
crash, there is always a backup system
on-line, ready to take over. As a result,
there are two of everything
two
lamps behind each illuminated number,
two sets of control electronics, two computers, and two power circuits. The
only things that could not be duplicated
were the electromechanical seven-segment displays; more about these later.
Computer systems operating in tan=
dem or backup mode are a little more
tricky than meets the eye; the main difficulty being intercommunication between the computers, so that each one
can keep tabs of the other's operation.
Many hours of fine-tuning were devoted
to solving this problem, with various interesting deadlock situations manifesting
along the way.
-
Lamp control
Because the illumination of numbers
must compete with the bright -as -day
studio lighting, relatively powerful
lamps were required. Studio tests indicated that 40 watts per lightbox was required. This dictated the use of 240 volt
lamps, since the current consumption of
300 -odd low voltage lamps would have
been about 1000 amps!
Under normal circumstances, interfacing logic to 240 volt lamps is a simple
matter of using opto -isolators and triacs.
However in a television studio, the electrical noise generated by triacs can
cause terrible problems. In cases where
a simple on/off is all that's required,
noise problems can be avoided by ensuring that the triacs only switch at
zero -crossings of the AC cycle.
Unfortunately, this installation required more than on/off control. Each
lamp has three possible brightness
levels. Because most lamp failures occur
when first switched on from cold, a
`warmup' level is applied to keep the
filaments warm when the lamp is otherwise off. The next level is a visible 'on',
and the highest level is used for `highlight'.
The usual means of dimming lamps is
to use phase control, whereby a triac is
fired at some point into the cycle on
each cycle. By changing the delay between the zero crossing and the firing of
the triac, the amount of power delivered to the lamp can be smoothly
controlled. It's the sudden rush of cur12
ELECTRONICS Australia, August 1990
This studio action shot shows the screens of the two computers that control
the game. If either fails, the 'other takes over automatically.
rent that occurs when a triac turns on
mid -cycle that causes noise, and so in
this noise -sensitive environment, another solution had to be found.
In some applications, a technique
called integral cycle control can be
used, whereby power control is
achieved by switching power on for a
certain number of full cycles, then off
for some more cycles. The average
power is controlled by varying the ratio
of 'on' time to 'off. Unfortunately,
when using 50Hz mains, the on and off
times can get quite long, with the result
that lamps flicker visibly. For that reason, integral cycle control is usually
used only for heating.
In this case, the problem was solved
by using multi -tapped transformers to
provide different voltages for the lamps,
with triacs being used to select which
tapping is used, depending on the
brightness level required. Zero -crossing
switching is achieved by ensuring that
control signal changes are synchronised
to the mains zero -crossings.
Numeric displays
Various numeric displays are used to
show the player's numbers, the Pools
results, and cash values. The obvious
choice was seven -segment LED displays, which are now available in the
100mm-high units called for in this application. Unfortunately, things were
not to be so simple, as the studio lighting proved too much for the yellow
LED displays tested.
The so-called `superbright' red LEDs
were much more visible under the
bright lights, but unfortunately TV cameras respond very badly to red light
resulting in very blurry images.
Much leafing through catalogs eventually turned up the ideal solution: seven-
-
segment electromechanical
displays.
These units comprise seven segments in
the form of plastic vanes, which are
painted yellow on one face and black on
the other. A small solenoid on each
vane is used to flip it over, to show either yellow or black as appropriate.
The advantage of these displays in
this application is that they rely on reflected light, rather than emitted light,
so that the brightness and contrast increases as the ambient light increases.
The difficulty, from Right Hemisphere's point of view, was that 'these
devices are not as easy to interface and
control as conventional seven -segment
LEDs, requiring relatively large current
pulses to flip the vanes. As with the
lamp controllers, there was nothing
available off-the -shelf, and suitable interfaces had to be designed, tested, and
built in short order.
Another unusual problem concerning
the numeric displays was that of the
dual redundancy of the system. As mentioned previously, the whole Telepools
system has been designed as two independent systems working together to
provide a backup in case of component
failure or some other breakdown.
Whereas each illuminated number on
the board could contain two lightbulbs
without looking strange, it was obviously not possible to provide two identical sets of numeric displays.
Fortunately, the displays themselves
are inherently quite robust, and not
likely to fail except from physical abuse.
This type of display also has the fortunate characteristic of inherent memory,
which is another term for mechanical
latching; once set to show a particular
digit, the display stays in that state even
if the power is turned off.
The most likely causes of breakdown
under control of the computer. These
sounds are used to indicate prize wins
and other special occurrences.
Various ways of outputting sounds
under computer control were considered. Generating the sounds using software was ruled out, as that would limit
the range of sounds to electronic -sounding beeps of various types. To achieve
total flexibility of sounds, a `sampled
sound' technique was required.
Although it would be possible to store
the sounds in digitised form on disk,
then load them into RAM and play
them out through a DAC on a parallel
port, this would have occupied too
much RAM and chewed up a lot of processor bus bandwidth.
The task was offloaded onto a peripheral device, designed especially for the
job. A separate box was designed containing digitised sounds stored in 1
megabit EPROMs. To play a sound, the
main computer simply writes a control
byte to a parallel port, and from there
on the external hardware takes care of
clocking the data out of the EPROMs
and turning it into audio.
of the numeric displays is failure of one
of the solenoid drivers or a power supply, or a dodgy interconnecting cable.
To ensure continuity of operation in any
of these events, a rather unusual 'dual
port' arrangement was devised for the
displays. Each display has been fitted
with a circuit board with diode logic, to
allow two independent control cables to
feed the one set of solenoids independently. This ensures that the only common point is the display device itself, so
that in the event of failure of any of the
electronics, the redundant (backup) circuitry can take control.
Voice control
The main attraction of the Telepools
game is that a player participates via
phone from home. This is achieved by
feeding the player's voice into a spe-
cially developed interface, which causes
a random selection to be made when
they say the word `Pools' into the
phone.
To achieve this, more custom circuitry
had to be designed.
To detect the word `pools' in particular, while rejecting all other words,
would present a significant problem.
However, this is not really necessary for
the Telepools game; the only requirement being that when the player speaks,
it is reliably detected, and that the system be immune to noise and other va-
Software
Sound effects
The software required to make all
this equipment do what you see on TV
is no trivial piece of code, requiring
many things to operate simultaneously.
For example, when the game is in its
`idle' mode (waiting to play with just
lights flashing), about 300 lamps are
being individually turned on and off at
the right times. This involves a large
volume of data being sent across the
serial links to the gameboard, and a fair
amount of computing to make the
lamps execute the required patterns.
Once the game is under way, each of
the seven -segment displays' segments
must do the right thing at the right
time, and while that's happening sound
effects are being produced and the
phone input monitored. All in all, the
20MHz AT computer does not have a
lot of spare time!
The Lotteries Office has scrutinised
the project at every stage to ensure the
game is absolutely fair, especially in the
area of `random' selections. The usual
way of achieving so-called `randomness'
in computers is to use a pseudo -random
number sequence. This was not considered random enough for this game, and
alternative techniques had to be developed.
For reasons of security, the details of
this must remain a secret. Be assured,
however, that there is no line of program even remotely resembling 'IF
As the game progresses, a number of
different sound effects are produced,
PLAYERNAME = VOGEL THEN
PRIZE = $1000000'!
garies of the phone system.
Much experimentation was required
to determine the best way of achieving
this. The detection system is based on
recognising the envelope function of the
trigger word `Pools'.
For these experiments, a peak detector with a time constant of a few milliseconds was hooked up to a phone and
the resulting envelope watched on an
oscilloscope. By saying `Pools' hundreds
of times in different ways, an average
picture of the envelope shape was arrived at. Having determined the limits
of the rise and fall times expected, circuitry was designed to detect envelopes
within those limits.
To accommodate the wide variation in
signal levels to be expected from a
phone line, a long-timeconstant AGC
circuit was added at the front end. A
bandpass filter, to remove hum and
noise outside speech bandwidth, completes the detector.
The result is a very reliable `Pools'
detector, immune to the pops, clicks,
hums and buzzes which occur unpredictably on the line.
.
NOW AVAILABLE
AGAIN!
--
I
'n ;'ran
81aa"a
WWI
The first edition
proved very
with
students
and
popular
hobbyists alike, and sold out. If you
missed this revised second edition
on the news stands, we still have
limited stocks.
Available for $5.95 (including
packing) from
postage and
Reader
Australia
Electronics
Services, PO Box 227, Waterloo
2017.
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ELECTRONICS
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READER INFO NO. 3
ELECTRONICS Australia, August 1990
13
PHILIPPINE T
DE
MI
Executives from five leading electronics manufacturing firms in the Philippines visited Sydney
recently, to meet their counterparts in the local industry. The aim was twofold: to expand the
markets for their products, as well as to promote the benefits to Australian firms of using their
facilities and human resources for cost effective off -shore manufacturing.
by JIM ROWE
MIR
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The clock display assembly area at Pricon Microelectronics, in Taguig, Metro
Manilla. Currently PMI's plant is of 80,000 square feet.
The Philippines has been active in
electronics manufacturing for many
years, although until relatively recently
most of the firms were essentially performing off-shore assembly for companies in the USA, Japan or Europe
either as subsidiaries or contractors. This
is witnessed by the `Assembled in the
Philippines' legend on many of the IC's
and other components marketed by
large multinational firms such as Intel,
National
Semiconductor,
Fairchild,
Motorola, Philips Components, Texas
Instruments, Telefunken, AMD, Zilog
and Analog Devices.
But more recently, as the industry
and its managers have gained experience, many of the Philippines' original
contracting assembly firms have established themselves as autonomous manufacturers
developing their own products and export markets. Newly established firms have joined them, often set
up by keen and entrepreneural young
engineers.
-
-
14
Philippines' electronics manufacturing
industry is in a very healthy state, and
growing rapidly. So much so that some
observers have predicted that the country is shaping up as the next international focus for electronics manufacturing, following hard on the heels of Taiwan and Korea. And as part of its
growth strategy, the industry is sending
trade missions to many different countries
especially in the Pacific region
to promote both its products and its re-
ELECTRONICS Australia, August 1990
The Philippines' Government has also
been working to encourage further investment in electronics manufacturing,
by both domestic firms and domestic foreign joint ventures. It provides a
variety of incentives including tax holidays, duty exemptions for imported
capital plant, tax credits on locally
sourced capital plant, exemptions from
export taxes and duties, and so on.
Three special `export processing zones'
have also been established, in Mactan,
Baguio and Bataan, to encourage fully
foreign -owned firms wishing to set up
export -only manufacturing plants.
Special Customs arrangements have
also been established for the semiconductor industry, which is accorded `vital
industry' status. Semiconductor assemblers and manufacturers are exempted
from pre -delivery Customs inspection,
in recognition of the fast pace of the industry and the short cycle times re-
quired to maintain competitiveness.
The nett result is that today, the
The recent Electronics Trade Mission
to Sydney was organised as part of the
Trade and Investment Promotion Program
(TIPP),
sponsored
by
the
ASEAN -Australian
Economic
Cooperation Program (AAECP) to boost
trade for Philippine electronics and electrical manufacturing and products. The
actual organisation of the mission was
carried out by the Philipines' Center for
International Trade Expositions and
Missions (CITEM).
The five executives who made up the
mission were Mr Lawrence Qua, President of Complex Electronics Corporation; Mr Julius Labrador, President of
Labtech Manufacturing Industries and
Labrador Electronics Corporation; Mr
...rmrin.
l
im
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-i-' r-
SSION tISITS S
Alfredo Pacho, President of Pricon Microelectronics Inc; Mr Hilary de Leon,
General Manager of Mitech Corporation; and Mr Abel Balleras Jr, General
Manager of Beltron Computer Philippines, Inc. Also accompanying the executives was CITEM representative Mr
Vicente Uy.
Complex Electronics Corporation is
based in Makati, Metro Manilla, and is
in fact the oldest electronics subcontractor in the Philippines. It has been a pioneer in surface mount technology, and
produces electronics subassemblies for
fax machines, hard and floppy disk
drives, remote controls, radar detectors,
VCRs, optoelectronic displays and so
on. It also produces a wide range of
components, including opto couplers,
switches, bridge rectifiers and coils.
Complex forms part of a trio of companies, the other two members being
Ionics Circuits and Onyx Inc. Ionics
specialises in hi-rel and advanced packaging, while Onyx provides the group
with technology support and marketing
in the USA.
Labtech Manufacturing Industries and
Labrador Electronics Corporation are
both based in Cubao, Quezon City.
Labrador Electronics was founded by
Mr Julius Labrador in the 1960's, as a
contract manufacturer of TV and radie
receivers. In the 1970's it shifted to the
industrial electronics area, producing a
range of automatic voltage regulators
(AVR's) and uninterruptible power supplies (UPS's). These have been mar-
o
.
..
1,/y.
i=a
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Testing automatic AC voltage regulators at Labrador Electronics Corporation,
in Cubao, Quezon City. LEC also makes a range of uninterruptible supplies.
keted very successfully in the Philippines under the `Wilson' and `Powerlab'
brandnames, with annual sales currently
around 20 million pesos mark (there are
approximately 20 pesos to the US dollar).
Labtech was also founded by Julius
Labrador, in 1976, as a semiconductor
manufacturing subcontractor to ShinElectric Manufacturing of
dengen
Japan. For some time it was the only
manufacturer of bridge rectifiers in the
ASEAN region. Today it employs over
600 people, and produces over 140 million semiconductor products per year
including bridge rectifiers, transistors
and transistor arrays. Annual sales ex-
-
74,
:-
..
r
d
_
Left: PMI's assembly line for cordless
telephones. Above: Final assembly of
uninterruptible PS's at Labrador
Electronics.
ceed 200 million pesos.
Pricon Microelectronics Inc. is based
in Taguig, Metro Manilla. Founded in
1985, it initally specialised in the manufacture of magnetic recording heads.
Since then it has expanded to perform
contract assembly of cordless telephones, scanning receivers (both handheld and desktop) and clock LED assemblies, as well as general assembly of
PCB modules. PMI's plant is currently
80,000 square feet, and includes a Class
10,000 production assembly area and a
clean room.
Mitech Corporation, based in Makati,
Metro Manilla, specialises in the design
and manufacture of innovative microprocessor -based equipment. The firm's
products include handheld and desktop
personal computers, an intelligent telex
interface for PC's, modems, air conditioning and security controllers, data
logging/process control systems and barcode reading systems. Mitech's latest
product is Logbox, an employee timekeeping and payroll system using magnetic cards, designed to replace bundy
clocks and timecards.
Beltron Computer Philippines, Inc. is
a leading manufacturer of micro and
personal computers, based in Malabon,
Metro Manilla. It currently produces
around 3500 machines per month, of
which 10% is exported to the USA.
The selection of the firms represented
in the Mission was made on the basis of
recommendations made by Tim Gee, a
Senior Consultant at Imras Consulting
a Sydney firm which specialises in in -
-
ELECTRONICS Australia, August 1990
15
Philippines Trade Mission visit
education. Current annual enrolment in
universities and tertiary colleges is
30,000, while over 150,000 are enrolled
in technical and vocational schools.
Around 20% of all university and college graduates are in engineering
a
particularly high percentage.
English is the most widely spoken foreign language, and the Philippines is in
fact regarded as the third largest English-speaking country in the world.
In terms of electronics manufacturing,
the Philippines can offer labour costs
around 10-20 times lower than in developed countries, coupled with the
ability to provide fast turnaround and
delivery. At the same time the high
educational standard and level of familiarity with English, among its workforce,
are factors giving the Philippines a
strong potential advantage over other
developing Asian countries.
"The Philippines has a great potential
in the Australian market, because of the
low labour costs", emphasises consultant Tim Gee.
From my brief meeting with the members of the recent Trade Mission, I
gained the distinct impression that the
Philippines' manufacturers are not only
keen to exploit this potential, but well
qualified to do so.
-
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testing station for semiconductor devices, at the Labtech Manufacturing
Industries plant in Cubao, Quezon City.
A
ternational market research analysis and
strategy. Mr Gee visited many factories
in the Philippines, and prepared a report for the Philippines' Consulate.
Each of the firms selected has export
experience, and has demonstrated
committment to servicing customers
different parts of the world.
The Philippines has a population
around 57 million, with a high level
its
in
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ELECTRONICS Australia, August 1990
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READER INFO NO. 4
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BRAND NAME BARGAINS
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SOFTWARE
Microsoft Word for Windows
$525
Microsoft Works (New Version)
$210
Lotus 123 V3
$795
Lotus 123 V2.2
$650
PC Tools Deluxe V6
$200
Informix
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MONITORS & CARDS
Super VGA Monitors
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$675
20" VGA Colour Monitors
$1,990
Ati VGA Wonder Card
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Super VGA Card, 16 Bit, 512 K
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DISK DRIVES
20 MB Hard Drive (40 MSEC)
$350
NEC 40 MB Hard Drive
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$599
143 MB Hard Drive (12 MSEC)...$1,990
80 MB Hard Card Plus
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$1,470
PRINTERS
Panasonic
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HP Laserjet and Deskjet Series $CALL
Ricoh Postscript Laser
$6,590
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Microsoft Mouse
Logitech Scanman
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READER INFO NO. 5
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Get into computing, with this
complete ACER 500+ system
made by one of the world's largest
and most experienced manufacturers of personal
computers, and is 100% quality control tested to
ensure top performance and reliability. It is designed
to provide the most affordable starter system for
serious home and business computing.
The ACER 500+ gives you both MGA and CGA video
graphics support as standard, allowing you to run
both colour or graphics software on the paper -white
monitor without the need for expensive add-on
boards or colour monitors. It also comes fitted with
The ACER 500+ is
both serial, parallel and games ports as standard, so
that you can connect a printer and modem directly
again without any expensive adaptors. So whether
you're a beginner or a serious professional user, the
ACER 500+ is a great starter system.
Features include V20 processor with selectable
4.77MHz or 8MHz clock speeds; a real time clock; full
640K of memory; dual 5.25" disk drives; 8087-2
co-processor socket; separate 84 -key keyboard;
-
MS-DOS
operating system with GW-BASIC; and
The ACER 500+ system pictured above Includes computer (X-8061), paper-white 30cm monitor (X-2400), 9-pin
135cps dot matrix printer (X-3225), Bit Blitzer 12E 300/300bps and 1200/1200bps communication modem
(X-3306), and the Better Working Eight -in -One integrated software package (X-9402). These come complete with
all interconnecting cables (X-8614, X-8007) plus a bonus box of 5.25" diskettes (X-3501), a printer stand
(X-3814) and printer paper (X-1185), to produce a full 'ready to run' system
for an amazingly low price:
-
UNBEATABLE VALUE!
above system can be ordered from your nearest
Dick Smith Electronics store or dealer, or ordered
direct by phoning (008) 22 6610. Sydney callers
phone 888 2105, or fax (02) 805 1986.
The
18
ELECTRONICS Australia, July 1990
12
months warranty.
ONLY
1995
DIC
ELE
RONICSMITH
THAT'S RIGHT,
by arrangement with Dick Smith Electronics
we have THREE of these superb ACER 500+ computer systems - each worth $1995
won over the next three months by lucky Electronics Australia with ETI subscribers.
Each system includes ACER 500+ computer (X-8061),
30cm monitor (X-2400), 9-pin 135cps dot matrix printer
(X-3225), Bit Blitzer 12E 300/300bps and 1200/1200bps
communications modem (X-3306), all necessary
cables, MS-DOS operating system, the 'Better Working
Eight -in -One' integrated software package (X-9402), a
bonus box of 5.25" DSDD diskettes, a printer stand
and pack of printer paper
a package valued at
$1995.
to be
How do YOU have a chance of winning one of these
superb systems? It's easy. Simply subscribe to
Electronics Australia with ETI, or extend your current
subscription for a further 12 months, between NOW
and September 28, 1990. All new/renewing/extending
subscriptions received during each month (July,
August and September) will be registered, and one
lucky subscriber from each month's group will win
one of the three computer systems.
-
So subscribe, or
-
renew/extend your subscription NOW!
ONLY $47 FOR
12 MONTHS
(12 ISSUES) incl. postage
SAVE OVER 12%
1
with
Australia's biggest, brightest and top selling electronics
magazine
have it home delivered each month
-
BONUS:
EVERYONE who subscribes, renews or extends
will receive absolutely FREE this economy pencil blow torch
great for heat shrink work, silver soldering, brazing, glass
work, etc. It fits easily in the pocket and Is powered by
butane gas (the same as used in cigarette lighters, etc.).
Incredibly handy and normally sells for $15.95
but yours
free!
-
-
NOT ONE, BUT THREE OF THESE
SUPERB COMPUTERS TO BE WON!
BUT HURRY
To enter simply fill out the coupon attached and
place it in the reply paid envelope supplied
if
the coupon and the envelope are missing, send
your name, address, phone number, cheque,
money order or credit card details (card type,
card number, expiry date and signature) to: Federal Publishing Company, Freepost No.4, P.O.
Box 227, Waterloo NSW 2017. Any enquiries
can be made by phoning (02) 693-6666. Unsigned orders cannot be accepted.
-
1. The competition is open only to Australian
residents authorising a new/renewal subscription
befbre last mail 28.09.90. Entries received after
closing date will not be included. Employees of
the Federal Publishing Company Pty Ltd and Dick
Smith Electronics and their families are not eligible to enter. To be valid for drawing, the sub-
- THIS OFFER ENDS September 28,
scription must be signed against a nominated
valid credit card or if paid by cheque, cleared for
payment.
South Australian residents need not purchase
magazine to enter, but may enter only once by
submitting their name, address and a hand -drawn
facsimile of the subscription coupon to Federal
Publishing Company Pty Ltd, P.O. Box 227, Waterloo NSW 2017.
2.
a
3. Prizes are not transferrable or
and may not be converted to cash.
The judges decision is final
spondence will be entered into.
4.
exchangeable
and
no corre-
Description of the competition and instructions on how to enter form a part of the competition conditions.
5.
1990!
The competition commences on 25.06.90
and closes with last mail on 28.09.90. The draw
will take place in Sydney on 03.10.90 and the
winners will be notified by telephone and letter.
The winners will also be announced in The Australian on 06.10.90 and a later issue of Electronics Australia.
6.
7. The prizes are: Three Acer 500+ computer
systems
each valued at 51995
total value
-
-
55985.00.
8. The promoter is Federal Publishing Company
Pty Ltd, 180 Bourke Road, Alexandria NSW
2015. Permit No. TC90/0000 issued under the
Lotteries and Art Unions Act 1901; Raffles and
Bingo Permit Board Permit No.90/0000 issued on
Permit
No.TP90/0000 issued
00/00/90;
ACT
under the Lotteries Ordinance, 1964.
' S HIGHLIGHTS
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*-7
SOXY LAUNCHES 'DATA DISCMAN' - CD-ROM BOOK
sells for only 58,0011 yen
approximately $580. This includes a sample
CD-ROM disc storing English/Japanese.
Japanese/English and three Sanseido
Japanese language dictionaries.
The DD -I has a keyboard based on
the Roman alphabet. and allowing for
several methods of data retrieval: word
search, keyword search, menu search.
multi search or consultation search. All
necessary retrieval software is built into
an internal ROM. The swing -out monochrome LCD screen has a resolution of
256 x 21111 pixels displays 10 lines of IS
characters, scrolling as required to read
the retrieved text.
Other features of the DD -I include a
built-in video adaptor for displaying the
retrieved data on a TV screen, and the
ability to play normal 80mm audio CD
'singles' via headphones. The unit
comes with both an AC power adaptor
and a rechargeable battery pack. but
will also run from a car battery via an
adaptor cable.
Sony says that a range of database
CD-ROMs arc being produced by other
publishers, to suit the DD -I. These includc textbook.. Inr\el ,_uides. dictionaries. instruction manual. and so on. At
least 18 titles \sere expected to he
released on Julu I. It certainly looks as
if the 'I)ata Discman nt:n %sell become
the first true 'electronic hook'.
In a move that may well mark the
beginning of a new era in data retrieval.
Sony Corporation has launched a new
CD-ROM based 'Data Discman' or
DD -I. on the Japanese market. The
unit takes 80mm CD-ROM disks, and
at the touch of a button displays the
stored data on a built-in LCD screen.
Measuring only 161) x 108 x 42mm and
with a weight of only 551) grams. the
DDI is easily handheld. In this it carries
on the tradition of Sony's previous
audio cassette 'Walkman' of 1979. its
audio CD 'Discman' of 1984 and the
'Video Walkman' released only 18
months ago.
In this case the unit is functionally
equivalent to current CD-ROM based
retrieval systems using a personal computer linked to a CD-ROM drive, and
running suitable data retrieval software.
However as well as being very much
smaller and easier to drive, the DD -I is
also much less expensive: in Japan it
NEW HYDROGEN MASER
HP & OKI TO BUILD PCB
PLANT Ill PEURTO RICO
VERY LOW CURRENT
Hewlett-Packard of the USA and Oki
Electric Industry of Japan have announced an agreement to build and
jointly operate a printed -circuit -board
manufacturing facility in Puerto Rico.
The joint venture has begun securing
construction and operating permits from
the Puerto Rican government.
Together, the companies will invest
$40 million to construct a 115,000 square -foot plant at HP's site in Aguadilla. HP's Peurto Rico operation will
use the boards in its computer products.
Oki's portion of the jointly manufactured PC boards will be sold on the
open market.
Construction is expected to be completed in 1991. The plant ultimately is
expected to employ 200 people.
Researchers at the University of California at Santa 13arbani claim to have
produced the first surface-enuttin semiconductor laser to operate at a current
milliamp - at least
level of around
30-40r'i the current level of any previ-
FREQUEL ICY STAXDARD
Anritsu in Japan
has developed a new
hydrogen maser frequency standard.
The unit is a super-precise frequency
standard, generating a microwave signal
which is produced by the stimulated
emission of electromagnetic waves during hydrogen atom state transistions.
The hydrogen maser has the best frequency stability of all available frequency standards, being in the order of
10-rs
Because of this excellent frequency
stability, the hydrogen maser frequency
standard is suitable for use in advanced
scientific measurement fields. These include terrestrial very long base line interferometers (VLBIs), space VLBIs
and navigational tracking systems for
space exploration.
20
ELECTRONICS Australia, August 1990
SEMICONDUCTOR LASER
I
ous device.
The new team. led by Professor Larry
A. Coldren. has produced the first devices to have a threshold current density
of less than IIIIII) amp. per square centimetre. This level is regarded hk researchers as the maximum allos%able for
practical development of phoumie ICs.
which will use light signals for ssitchini2
and signal processing as an alternati\e
to electronics.
The new UCSI3 chips operate at a
density of only 6111) amps per square cm.
TI, KOBE TO
MAKE CMOS CHIPS
Texas Instruments and Kobe Steel
have jointly announced an agreement to
establish a joint -venture company, to
manufacture advanced semiconductors
in Japan. The venture will manufacture
primarily complementary metal oxide
semiconductor (CMOS) logic devices,
including very large scale integrated
(VLSI) circuits and application -specific
integrated circuits (ASICs).
Semiconductor products manufactured
by the joint venture will be sold exclusively to Ti for distribution and sale by
Ti to customers in Japan, throughout
the Asia -Pacific region, and in other
world markets.
Design work on the wafer-fabrication
facility for the joint venture will begin
promptly, with construction in Hyogo
Precture in the Kansai region of Japan
to start in early 1991 and be completed
by the end of 1991. Full-scale production is expected by mid -year 1992 based
on advanced submicron CMOS technology.
Total investment in the initial wafer
fab is estimated at about US$350 million, including land, building and equipment.
SIEMENS & IBM TO
BUILD 64Mb DRAMS
Siemens of West Germany and International Business Machines Corporation
of Armonk, NY (USA), have signed an
agreement to jointly develop 64 -million bit memory chips. The agreement also
provides for discussion of further cooperation on subsequent semiconductor
memory generations.
Joint development of the 64 -million bit DRAM will begin immediately at
Siemens and IBM. The common activities will be concentrated at IBM's new
advanced Semiconductor Technology
Centre in East Fishkill, New York and
use the resources of both the Munich
facility of Siemens and the Essex
Junction/Vermont facility of IBM. Production of the chips will take place in
manufacturing facilities of the respective
companies.
Each company will share equally in
the development costs.
The goal of the project is to have a
world standard 64 -million -bit DRAM
ready for commercial introduction in
the mid -1990's. Work will concentrate
on the chip design and the process technology, using the most sophisticated
tools and materials available.
NEC RELEASES 'NEXT GENERATION' PORTABLE PHONE
NEC Australia has released the 'revoits
lutionary' P3 portable 'phone
smallest and lightest ever mobile communications device. Weighing a mere
400 grams, with dimensions of only 172
x 55 x 24mm, the P3 represents the beginnning of what a senior Japanese executive has dubbed the Personal Communications Era'.
The P3 is, at last, a truly `mobile and
portable' phone that lives up to its description. Weighing around half as much
as most of its competitors, it can easily
be slipped into a pocket without discomfort.
There is no need to remember 'phone
numbers with the P3. It features an
easy -to -read 30 character alphanumeric
display, with instant search of 99 stored
names and numbers. Its long-life compact battery can be switched to `stand
-
-or
NEC's new P3 portable phone.
by' mode, thus enabling the P3 to await
calls for 18 hours and provide 80
minutes of continuous conversation.
The P3 was officially released in Australia by Mr Tomiaki Mizukami, General Manager of NEC Corporation's
mobile media terminals division.
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DIGITAL OPENS AUSSIE MANUFACTURING PLANT
of this total. Petre Seuffert, Digidirector of Australian manufactursaid that Australia's proximity to
emerging markets of Asia makes
local manufacturing a viable global exercise for Digital.
"While the Partnership agreement
provided an impetus to begin manufacturing in Australia at this time, we can
say that the program has now reached
'critical mass' and will continue independently of the Partnership agreement," Seuffert said.
Digital is concentrating the manufacture of network and communications
hardware products in Australia. Seuffert
explained, "Australia is already a centre
of networking and communication expertise, partly because of having a relatively small population spread over a
large land mass. We are building on this
expertise to make Australia an exporter
of network and communication technology to the world."
half
tal's
ing,
the
Digital Equipment Corporation has
established an Australian manufacturing
plant, in the Sydney suburb of Lane
Cove. Using the new facility and with
the involvement of local companies,
Digital plans to increase its hardware
exports by 100% per year over five
years, and to approximately $A70 million by 1992.
Digital plans to manufacture 11 network and communications hardware
products in Australia for export to the
Pacific Rim and world-wide. Six products arc currently being manufactured in
Australia, three of them having been
engineered locally. These are being
manufactured at the Lane Cove facility,
at which more than 70 staff are employed.
Through its Partnership for Development agreement with the Government,
Digital will progressively increase exports to $100 million per year. Australian manufacturing will account for over
ELECTRONICS Australia, August 1990
21
NEWS
CONVERTER FOR PABX'S
Telecom Australia has launched a
new product which allows businesses to
use the latest ISDN technology without
overhauling their office systems. The
new product has been jointly developed
by Telecom and Australian telecommunications supplier Jtec, and is one of
the first products to take advantage of
Australia's world leading Integrated
Services Digital Network, introduced in
Australia in July 1989. ISDN combines
voice, data and video, in digital form.
The Macrospan 1000 multiplexer effectively converts analog signals into a
digitised form meaning that business
customers will be able to connect to
ISDN without having to upgrade their
non -compatible PABX's.
National Manager for Telecom ISDN
Services Val Kangsanant says that the
introduction of ISDN Macrolink ahead
of other nations, has opened up unique
opportunities for Australian industry.
"Local manufacturing and software
industries have been given a rare opportunity to develop network equipment
and customer terminal products for
Macrolink connection ahead of other
nations", said Ms Kangsanant.
"This not only stimulates home grown
technological development and expertise, but also enhances Australia's export opportunities
Jtec is an example
of local companies taking advantage of
the opportunity".
Australia and IBM Australia/NZ have agreed to develop
co-operatively 'end-to -end' Information services, beginning with a 2Mbps
interface between IBM's Token Ring LAN and Telecom's FASTPAC network.
Here IBM's MD Brian Finn (L) and Telecom's MD Mel Ward clinch the deal.
Telecom
NULLABOR TRAINS GET PHILIPS UHF MOBILES
Australian National Rail has awarded
Philips Telecommunications and Data
(TDS) a $300,000 contract to supply
more than 250 of its locally manufactured FM91 Tfband UHF mobile radio
transceivers.
The FM91's will form the mobile
component of Australian National's 45
base -station radio network, operating
via a new fibre optic communication
link across the Nullabor Desert.
The FM91 mobiles are being installed
-
DEATH OF INTEL
FOUNDER, IC INVENTOR
Dr Robert Noyce, founder of Intel
Corporation and one of the inventors of
the integrated circuit, has died at his
home in Austin, Texas at the age of 62
after suffering a heart attack.
As well as being one of the two independent inventors of the IC, Dr Noyce
also played an inportant role in Intel's
development of the first microprocessor
chip
the 4004, which effectively
began the microcomputer revolution. In
1979 he was awarded the National
Medal of Science by President Carter,
and then received the National Medal
of Technology from President Reagan
-
in 1987.
For the last couple of years he had
been president and chief executive of
Sematech, the Austin -based research
consortium organised to help the US
chip industry 'catch up' with Japan.
22
on road and rail -based maintenance vehicles and will be used in conjunction
with the optical fibre system.
The mobiles will be part of a communication network designed to replace
the previous open wire pole telephone
system, running parallel to the line for
more than 1600 kilometres. The pole
line, installed 10 years after the line was
formally opened in 1916, has been in
constant use until the changeover to
fibre optics in April.
SEMI MEDAL FOR 'MEGA PROJECT' LEADERS
For their services as leaders of the
European Mega Project, Dr Willy Beinvogl of Siemens and Dr Roel Kramer of
Philips have been awarded the SEMI
medal, in recognition of their contribution as project leaders to the establishment of a European industrial co-operation.
The objective of the co-operation,
which encompassed research, development and manufacturing technology,
was the achievement of world -class
standards in the sub -micron circuits.
The success of this project, according to
the SEMI organisation based in the
USA, paved the way for continued
European co-operation in the area of
semiconductor manufacturing.
As part of the Mega Project, which
ran from 1984 to 1989, Siemens and
ELECTRONICS Australia, August 1990
Philips invested a total of DM2.4 billion
(approx. $A2 billion) towards the development of a sub -micron memory product ready to go into production. Siemens had concentrated its efforts on dynamic memories (DRAM) made in
CMOS technology. By starting 4Mbit
DRAM production in the third quarter
of 1989, the goal of closing the technological gap to world leaders was
reached.
SEMI (Semiconductor Equipment and
Materials International), the organisation sponsoring the award, is an international association of over 1300 companies which are active in the field of
semiconductors. The award winners
were selected by a European panel
which comprises 12 representatives from
industry and research institutes.
SYDNEY FIRM MAKING TOROIDAL TRANSFORMERS
$2M PROGRAM TO
1
DEVELOP VIDEO CODEC
A joint $2 million research and development program has been announced
by Telecom and Texas Instruments, to
0d24
rf
ll
Toroidal transformers offer higher efficiency and lower leakage flux than
standard E -I cored types, but in Australia they've traditionally been higher in
price due to the specialised winding
techniques required and the absence of
local manufacturers.
The situation has changed, however,
with Sydney firm Tortech now set up
and producing a range of toroidal transformers at its factory in North Strathfield. The range includes models from
30VA to 2500VA, and Tortech's winding machines can provide an optional
1
1
electrostatic shield if required. An outer
magnetic shield can also be provided if
necessary, to achieve furthe-r reduction
in leakage flux.
A range of transformers rated from
50VA to 300VA and approved to AS
3108-1984 is also available.
Tortech says that because of local
manufacture, plus the use of highly efficient toroidal winding machines, its
transformers are very price competitive.
Further details are available from
Tortech at PO Box 194, North Strathfield 2137 or phone (02) 736 1516.
NEWS BRIEFS
Promark Electronics has opened a South Australian office, which will be
managed by Mark Chapman. The address is 297 Pirie Street, Adelaide 5000 and
the phone number is (08) 236 0108.
Tim Wortman, who established the Marconi Instruments operation in Australia
and has more recently been Australasian Business Manager for Philips -Fluke, has
just established his own test and measurement distribution firm. Called Tech -Fast
T&M, the company will provide fast delivery of DMMs, scopes, counters etc. The
address is 14B Maxwell Street, Turramurra 2074, and phone number (02)
AUSSAT GETS $100M
CAPITAL IXJECTION
Aussat, the national satellite carrier,
to be provided with a one-off injection of $100 million in equity. Minister
for Transport and Communications Kim
Beazley, said the decision followed consideration by Federal Cabinet of Ausis
988 3865.
Rhode and Schwarz has relocated to 63 Parramatta Road, Silverwater 2141
and the phone number is (02) 748 0155.
US manufacturer of switching power supplies and DC -DC converters Power
General has appointed Priority Electronics as its exclusive agent in Australia.
Arista has made some new appointments, with Rudi Langeveld as Managing
Director, Ken Crocker as Financial Controller, Peter Trautner as Warehouse Manager and Lorraine Lee as Sales Representative.
Symetrix of USA has appointed Audio Telex Communications as the Australian distributor for its voice processing equipment. Audio Telex has offices in Sydney, Brisbane, Melbourne, Adelaide and Perth.
Alcatel STC-Cannon Components has shortened its name to Alcatel Components. The company does local manufacturing, assembly and testing of fibre
optic connectors.
Utilux has appointed lain Hamilton, a qualified metallurgist, as the Quality
Support Manager for the Head Office at Kingsgrove, NSW.
Perth based component and equipment supplier Altronic Distributors has
opened a wholesale branch office in Queensland, with Greg Liddelow as the
State Manager. The address is Suite 204, Toowong Towers, 9 Sherwood Road,
Toowong 4066 and the phone number is (07) 870 5161.
Sony Australia has appointed Mr Tadashi (Gus) Ishida as its new Managing
Director. Mr Ishida has been with Sony Corporation since 1963, spending 18 of
these years in the USA.
develop advanced 'in -office' video conferencing technology for Australia.
The new agreement is planned to result in the launch, in the second quarter
of 1991, of new teleconferencing technology which converts vision signals into
digital code. The digital encoder/decoder, called a digital codec, is to use the
latest TI TM320 digital signal processing
technology and incorporate several features which will greatly improve the
quality of existing video conference systems.
In announcing the agreement, Telecom's Manager of Fast Packet Services,
Mr Graeme Kidd said Telecom Australia placed considerable importance on
co-operating with worldwide companies
such as Texas Instruments in the development of equipment which will enhance and improve communications. Mr
Kidd said the development of the digital
codec coincides with the introduction of
Telecom's new switched broadband data
service 'FASTPAC'.
Fastpac will be the first national data
service in Australia to use high performance broadband switching in an optical
fibre environment.
sat's financial needs.
"The existing regulatory regime has
restricted Aussat's market and limited
its options for diversification", Mr
Beazley said.
"Although the company announced
its first after tax operating profit in
1988/89, it has become apparent that
market projections upon which deci-
sions for Aussat's long term future were
based are unlikely to be realised".
The long term future of all three telecommunications
carriers, Telecom,
OTC and Ausaat was addressed in the
Review of the Ownership and Structural
Arrangements among the three carriers.
The review was conducted by the Department of Transport and Communications which was due to report to the
Government by June 30.
ELECTRONICS Australia, August 1990
23
Simple method of
timing camera shutters
How do you check your camera's shutter opening times for
the various speeds? Elaborate electronic timing systems are
available, but they're expensive. Here's a simple technique
which makes use of the camera itself and almost any surplus
1500rpm electric motor.
by WILLIAM JAMES
it correctly and using Araldite, I fixed
an old 7" aluminium pulley. For added
security, I also fitted self-tapping
screws.
The face of the disc was undercoated
and then sprayed with four coats of
acrylic satin black. It was allowed to dry
overnight, then an old 10" gramophone
record was located in its centre, positioned horizontally and a heavy covering of white undercoat was sprayed
round the exposed portion of the rim.
When the record was removed, there
at home using relatively simple meth- was a clean black circle, 25cm in diameods.
ter, surrounded by a white rim, the
I have found that the apparatus most
main purpose of the rim was to exclude
convenience for me consisted of the fol- extraneous images.
A straight white line 1.5mm wide was
lowing:
then painted on the black circle, run1. A circular disc, 28 to 30.5cm in
ning from the centre to the edge of the
diameter.
white rim, using masking tape to protect
2. An electric motor capable of driving
the background. Two coats of white
the disc at known and steady speeds. enamel were applied, the tape being reUnder heading (1), I have in fact moved before the second coat had set
produced two discs. One, disc 'A' is hard.
The second, disc 'B' is intended espe30.5cm in diameter and cut from 2.5mm
aluminium sheet. Taking care to centre cially for the testing of focal plane shut-
This article deals with checking the
shutter speeds of cameras which can be
controlled manually - which still comprise the bulk of the instruments in use
today. You could take your camera to a
repair shop having a modern electronic
timer and for a fee, receive a certificate
as to the accuracy of the shutter speeds.
It is not always easy to find someone
who has one of these timers and, in any
case, there is the satisfaction of testing
things for oneself. As it happens, it is
quite easy to determine shutter speeds
ters. The basic principle is to be able to
photograph a thin white line on a drum
rotating at right angles to the direction
in which the shutter is travelling. Disc B
reduces the distortions produced by FP
shutters when photographing disc A.
I used a new chopping board made
for the kitchen. The board is a circular
piece of hardwood, measuring 28cm in
diameter by 2.3cm thick. An old 5" pulley was fitted to the back as per disc A.
The whole assembly was then sprayed
black. Six white lines were painted on
the rim of the disc, 1.5mm wide, at
right angles to the circumference and
equally spaced. Thus each line is 2.3cm
long.
To drive the discs, I used an induction -type electric motor, 1/8HP and with
a 1/2" spindle, from a scrapped tumble dryer. It has a load rating of 1425rpm
but the no-load spindle speed is higher.
When discs A and B were tried on
the electric motor with direct drive the
rotational speed was very steady, varying from 14% to 1497rpm
checked by
a digital tachometer, accurate to Irpm.
For shutter testing it is perfectly satisfactory to regard the motor as running
at 1500rpm.
I have also experimented with various
small electric motors. Using a lightweight disc these could be made to
work quite well. Speeds were checked
by an electro-mechanical counter activated by a bar magnet attached to the
-
The kinds of patterns obtained by the author's method,
using the 'face' and 'drum' discs respectively. In each
case the shutter speed can be determined from the
width of the sector or trapezoid.
24
ELECTRONICS Australia, August 1990
-"as
!=
for focal -plane shutters than
Two different types of disc can be used, with the 'drum' type at left somewhat better suited
used.
be
motor
can
of
kinds
Many
different
right.
type
at
the 'face'
disc and arranged to pass over a reed
switch. I was never able to get a reasonably priced counter to work reliably
above 700rpm, although rated higher.
However, motors can be geared up as
well as down and a dependable 1400rpm
was attained using parts from my son's
discarded Meccano set.
For the testing of camera shutter
speeds the actual photography is simple.
Mount the electric motor firmly. Fix
disc A securely to the spindle and adjust the motor to get the disc vertical.
Load camera with Kodak T-MAX 3200
film, mount the camera on a tripod, and
line it up to photograph the disc, filling
the frame as fully as possible and focus
carefully.
If this film is not available, choose
the fastest black and white film you can
get and experiment with 'push -development'. If the camera has no close -focusing facility, use a supplementary lens.
Two photographic lamps will suffice,
one on each side of the disc at about
one metre from the centre and at an
angle of 45°. The exposure information
assumes No.1 photoflood bulbs.
Start the motor and make exposures
as follows, three at each setting:
1/1000 at f/2.8 and f/4;
1/500 at f/4 and f/5.6;
1/250 at f/5.6 and f/8;
1/125 at f/8 and f/11
1/60 at f/11 and f/16
Process film in T-MAX developer for
11 mins at 21°C.
The resulting negatives will have
black and grey areas. The white rim will
show up as pure black. The circle will
be a light-grey colour and will have a
dark -grey sector, the sector perhaps
being an irregular shape.
After the negatives have dried, put
one in an enlarger and project its image
onto a sheet of white paper. With a
hard, sharp pencil cross-mark the centre
of the disc and the two points on the
circumference defining the outer limits
of the dark -grey sector. Remove paper,
draw lines from the centre of the circle
to the two outer points, then with a
protractor, measure the angle formed
by the radial lines.
For a speed of 1500rpm the correct
angles for the shutter speeds listed,
ranging from 1/1000 to 1/60 sec, are as
follows: 9, 18, 36, 72 and 144 degrees.
You can easily calculate the appropriate angle for any shutter setting at any
rotational speed. The formula is
s = (360 x a)/b
where 's' is the shutter speed, 'a' is the
number of revs per second and 'b' is the
measured sector angle in degrees.
While shutters of all types will give
some distortion of a fast-moving object,
the inter -lens shutters are very much
better than the focal plane type. In
many of the negatives radial lines will
be curved, both bending in the same direction, unless a sector is large, when
the curvature can be in opposite directions. The points for angle measurement
should be taken at the circumference
and at the two points, on a circumferential line, where the radial lines show the
maximum curvature. You may well
find, as I have often done, that the two
angle measurements are the same. Failing that, take an average reading of the
two angles and you will get an accept-
able result.
Disc B provides a better way of testing focal plane shutters. Using a spirit
level, position one of the white lines on
the rim horizontally in relation to the
centre of the disc and ensure that the
camera is set up on a tripod so that this
line is parallel to the centre of the lens
and that the lens flange is vertical. Use
a standard lens. Those of longer or
shorter focal length will introduce optical and mathematical complications.
The disc should be running at rightangles to the direction of shutter travel,
thus a camera with a vertical shutter
should have its body mounted vertically.
For a 35mm camera, fill the frame to an
image size of about 20mm and just be
able to see in the viewfinder, the two
white lines on opposite sides of the
'base' line. Focus on this line.
There is no way of ensuring that an
exposure with the disc running will produce an image in the centre of the negative. However, I have found in practice
that, on average, at least one in every
six exposures will have an image of a
line on or near the centre of the disc.
For assessment, a selected negative is
enlarged full-sized, i.e., to the width of
the rim. The image will be a parallelogram, but that will be the only apparent
distortion. The fast-moving vertical
shutters will give cleaner images and
less distortion.
Mark the edges of the image using
masking tape, swing the enlarger head
away and switch -on the ordinary lights.
With a magnifying glass measure carefully the distance between the two edge
Continued on page 144
ELECTRONICS Australia, August 1990
25
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Without controller
Q
80 M/BYTE VOICE COIL
W
CC
.9
TURN YOUR IBM* PC, XT, AT INTO A
FULLY FUNCTIONAL ANSWERING
MACHINE!!!
12 month warranty
$795
a
HARD DISK
IBM' compatible. 25 msec access. a
a
12 month warranty.
Without controller.
$1195
*
a
OI
J
*
t*
Q
0.
ddyas otter
unformaled eapeckis ranging from ITS High performance.
Mbytes to 3n2 Mbytes of storage within a wan.20 meec. alarag s.ek tim. end.
compact s I'2'peckaga sire
data transfer rare of 10 Mbhssec, the 70.
SCSI.
serial offers the speed moulted for mutt
The 700 Serbs drives otter the Industry
user, multi tasking &pallet. hone.
and ANSI standard SCSI Interface foe
Advanced Technology
easy systems lntsrgntlon. Th Interface
Th. 700 ..rlal disk drive hH an
Is en embedded (within drive form factor) advanced tin.rvolcao0 and dloaad
SCSI lmpiemnueon. SCSI Is en
loop dedicated servo technology and
merging standard for optimised system. Oast be Intehgnted Into weriistation., multi
int.grstlon and performance. n from your usar systems and network application.
system from devlca.unlgue
Reliability
charQrlstlea, such a. head and back (vary 700 Iles cen.ine el features
10.n1111cetlon,wli h Iha 700 serial PRIAM designed to maaknlea nll.bnlry and data
now .hest Ib benllllol using an
Integrity. Follows ouch as an automatic
embedded SCSI In small microprocessor- actuator, landlnsnlpping ron eand
alnat
Intag
mounts
u
geese HMI".nl.hock
based systems requiring high capacity,
a«Idnnl loss of valuable data.
high part°muaoce disk drives
i
170 M/byte X20046
IBM' XT' compatible
$159
51/4" 720K DRIVE
MByyt1e unformatted
IBM- AT' compatible
BABY AT` STYLE
COMPUTER CASE
1
$195
Cat.C11906
31/2" 1.44 M/BYTE DRIVE
44 MByte formatted
or 720K formatted
Double sided, double density
51/4- mounted
Small footprint Features
security key switch, 8 slot/
and mounting accessories.
Size: 360(W) x 175(H) a
405(D) mm
X11093......... _......»....»...... .$99
$299
Cat. C11911
*,
****,
X18009
SRO
ia:ryas
/,
a-sn7:nm
"NEW"
CPF s superior ,.dcultry design and
semr.Mnductor teWtology resporas
instantly to Soy potentially damaging
oier.vollage ensuring safe trouble
Iree operation
CPF Steering capaba',
helps ekmmate troublesome and
annoyingmtederence general hash
created by small notes Ouorescent
lamps and the like that threaten lye
perform nCe and seonen equipment
life of unprotected eiectt0ni5
gornpdnents
ONSIGHT VIDEO AND
AUDIO/ VIDEO
MONOTORING SYSTEMS
-260 volts
4
500 amps
for 2Ornsecood pulses
DEPENDING ON THE CAMERA'S PLACEMENT,
YOU CAN SEE AND / OR HEAR IF YOUR CHILD
IS AWAKE, SEE AND TALK WITH THE PERSON
AT THE FRONT DOOR, OR SEE IF SOMEONE IS
IN THE POOL.
WITH ITS BUILT IN INTERCOM ,THE VM200
ONSIGHT LETS YOU CONVERSE WITH THE
PEOPLE IN THE ROOM WHERE THE CAMERA IS
MOUNTED.
OPTIONAL CAMERA'S , MONITORS, AND
SWITCHERS ALLOWS YOU TO MONITOR
SEVERAL LOCATIONS AT ONCE.
Renewal clamping voltage: 275V
ditfe,enhal mode
Save a small fortune with these
Beefily 20 minute tapes. We impon
Direct so we can pass on the savings
Cat. 011141
U-9
10+
25+
p0.95
$0.90
$0.80
25 MHZ
TOWER SYSTEM
The 386 Tower PC is a high
performance system that's IBM-Ar
compatible. However, the
386 Tower PC gives you 4-8 times
the performance.
240 VAC MAINS SURGE
PROTECTOR / LINE
FILTER
This unit has Inbuilt M.O.V circuitry
preventing any AC power spikes or
surges entering
the product it Is protecting. An
additional feature has been added
to this unh. Line filtering and
conditioning circuits have been
included with the use of a torrid
coil which suppresses electro
magnetic interference (EMI)
caused by other appliances
operating In the AC system e:
computers, neon starters.
refrigerators etc. The PAC 18 is
sufficient for most domestic and
some commercial applications.
Approved by the Australian Dept
of minerals and Energy.
Appoval a N11361
X10092
$69.95
569.95
Cat.X10088
FEATURES:
Intel 80386- 25 Mhz
microprocessor
Switchable 25 Mhz
150W SWITCH MODE
POWER SUPPLY FOR
IBM' PC'/XT*
& COMPATIBLES
DC OUTPUT: +5/13A. -5V/0.5A
+
MByte fined. Total memory
expandable up to 16 MBytes.
Up to 2 MByte or 8 MByte RAM
Ill MM111 M
WM=MIti Ell IlMEItti
immediate equipment lallurel to
less obvious harm mat can draslicaey
shorten a system s lire
Spas RFI Prot.ntion:
DATA CASSETTES
ONLY $245
IlttilitIIINllaINlaMI
Ink e
atn:22
-
-a
Traditional telephone answering machines are
obsolete with the release of the NEW Voice Mail
X19084
The Fenton CPF Finned Eiecnonic
Stare Prof ente provides tlraecirve
electronic banter to nbCrOCO npunrs
primers telephone Systems and
moderns electronic typewriters
audio and stereo systems and other
Sensitive ebCtrOn.0 equipment
Tne CPF provides proles-bon them
dangerous $00115alspikes that can
cause anything Ircrn OboOus damage
SPECIFICATIONS:
Elect
IACI
I.
Card.
Not only can this card turn your computer into a 24
hour personal receptionist , but can answer with
different phone messages for particular callers.
Milton"
CONTROLLER CARO TO SUIT
In
*,
FILTER SPIKE ARRESTOR
Cat.C11901
1
,
CPF
CONTINUOUS POWER
51/4" 360K DRIVE
Switchable
*'
COMPUTER
CASES
500K unformatted,
A
.
380 M. /byte X20048
SCSI Interface card
QUALITY
JAPANESE DRIVES!!
^^ v
Sophisticated Voice coil mail system
Auto answering / Dialing
* II 100 voice mail boxes
Password protection
a
Message mailing
a U Auto redlaling
Beeperless remote control
Toll saver
Call screening
*
Electronic phone book
$1490
Works in background
$ 229$ *
Menu driven software
'$129
Simple and concise operati
* ** *** **** ** *
J1
*
The 700 series disk
HARD DISK
..
*
*Al
High Capacity.
ONLY $499
5
Cl)
Priam presents IS. 700 aerie.
rie. died
drives, members of a powerful PRIAM
family of advanced 5 1/a" disk drives.
20 M/BYTE HARD DISK
Drive with controller Card. IBM'
compatible. 12 month warranty.
Q'
AUTOMATIC TELEPHONE
ANSWER/ CALL CARD
f.
(Q)
cc
II
eft
G
J
"NEW"
I2V/4.5A -I2V/0.5A
Cat. X11096
$129
2
modules on system board or on
RAM card
Option for 80287 8 80387
co -processor socket
Operates in page mode with
interleave memory subsystem
Shadow RAM supported to allow
system BIOS to be executed on
system memory instead of slower
EPROM
Four 16 -bit I/O slot. Three 8 -bit
I/O slot, and one 32 -bit memory
slot.
8042 keyboard controller interlace
for AT compatible keyboard
Seven direct memory access
(DMA) channels
Chips and Technology chip set
AMI 386 BIOS/Phoenix 386 BIOS/
AWARD 386 BIOS (AMI Idled)
50 MByte hard disk. 42 MByte
formatted. Fast access.
VGA Card
$4995
200W SWITCH MODE
POWER SUPPLY FOR
IBM' Ar 8 COMPATIBLE
DC OUTPUT: +5/16A, -5V/0.5A
+12V/5A -12V/0.5A
Cat. X11097
$199
180W SWITCH MODE
POWER SUPPLY FOR
BABY Ar COMPATIBLES
$169
Cat. X11098
IBM XT' COMPATIBLE
CASE WITH
Ar STYUNG
j
I
VIDAli
EO ONLY
AUDIO / VIDEO
$489
$589
Now you can have AT styling in a
XT' size case. Features secunty
key switch, 8 slots, and mounting
accessories.
Sue: 490(W) x 145(H) a 400(D)
Cat. X11091
$99
GREAT SAVINGS GREAT SAVINGS GREAT SAVINGS GREAT SAVINGS
ñ
088 335757 TOLL FREE MAIL ORDER HOTLINE FOR CREDIT CARD ORDERS!
Iá
10911
'ems
o..
°<
b
l(ll
EGA SYSTEM
SPECIAL
-
^'r
JOYSTICK FOR IBM'
o¡
COPY HOLDER
(YU-H33)
Copy area 9 1/2" a 11"
Sliding line guide
VGA SYSTEM
SPECIAL
Flat metal base
C21060
$39.95
COPY HOLDER
(YU-H32)
Adjustable arms allows
easy positioning
Copy area 9 1/2" x 11"
Sliding line guide
Clamp mounting
C21062
$39.95
HS -3000
HANDY SCANNER
WIDE 4.13" (101nrn) scan wddt
100'200,3001400 *witched*
DPI resolution
Four encoding mode: BAS end Swim
pnem..
hall -tore
Thirty-two ehde of grey
(Witten acune., elate window for
occur*. scanner plecem.nt
YeIlow.green LED c.n light
Viubl.
BABY AT*
COMPATIBLE
COMPUTER!
2M/B RAM $1,695
o
programs for sequencing,
recording, composing, music
printing, patch editing, music
instruction and many other
applications.
Run all programs designed for
the Roland MPU-401
architecture
Socketed EPROM for easy
user replacement
1/3 length (short) card will lit in
any computer accepting
standard expansion card,
including laptops
including "Y" cable, external
connector box to transport is
unnecessary
"compatible" computers.
C14200
APPLE
$39.95
IIE
SERIES COMPATIBLE
These joysticks have adaptor
connectors to suit the Apple II,
IIc, Ile and 11. computers.
Features include selectable
"spring centring" or "free
floating". Electrical trim
adjustments on both arils, 360
cursor Control and dual fire
buttons.
C14201
r
$39.95
RITRON MULTISYNC
VGA COLOUR
MONITOR
1¿
GAMES
AT S/P GAMES
4 WAY FDD CONT.
(360-1.44M)
2 WAY FDD CONT.
(360-1.44M)
CLOCK CARD
$29
$59
6129
$80
$39
175(H) x 405(D)mm
Includes EGA monitor
With 20 kVByte Hard Disk $2195,
With 40 MByte V.C. H.D... $2495
With 80 MByte Hard DIsk.$2,795
a
Quality Auto VGA, EGA, CGA
monitor without the excessive
price lag!
Display Tube: 14 inch 90°
deflection P22 Non -glans, lint.
0.13mm dot pitch
Active Display Area:245 x165mm
Resolution:
800 dots(H) a 600 llnes(V)
Display Colour:
TTL input: 161664 colours
Analog input: unlimited colours
X14528
VOICE MAIL
PRINTER CARD
EGA CARD.......
2 WAY FDD CONT.
(360K) ..... _....... _
RS232 SERIAL/
CARD. _ ......................_
$39
639
RITRON CGA COLOUR
MONITORS
THE XITEL XM12E MODEM
Display Tube: 14 Inch 90
deflection 0.39mm Dots trio
pitch. Dark face screen.
I. d.Ngned
speed.
a
communication. and otlw CCITT end
Bell ey.tema.
KEY FEATURES:
1200 byte A.ynchronou
(CCITT V.22 B(111 or Bell 21281
300 bps Asynctronou.
(CCITT V.21 or Bell 103)
Full Duplex date communlnuone
on
T.Ncom PSTN 2
.t.rdrd
wire circuit
Auto -Dial, Aule.An.wer and
Auto-D(sconnecl (CCITT V.25 or Belt)
Automatic dais rate *election in both
Origin.*
and
Auto.An.,wr mode
Compatible with the mduelry
Stnd.rd Hama AT Commend S.l.
Tone or Pulse Dialling with
Cul Progrss Monitoring end
Inttnal SpaMer
_ _ ..... .....
...»
..6219
...
BBM 1234E
Auto V21, V22. 023. 022bie
Bell 103
Phosphor: P22
Resolution:640 dote (horizontal)
240 line (vertical)
for
.
212A
AayncrSynchionous Ealern.l
VERTICAL COMPUTER
STAND
Adjustable width from 115 188mm (4 1/4' 7 1/4")
AcComodates IBM PC/XT/AT
and most compatibles
Light weight and durable
C21076
t
$29.95
X14526
RS232/ SERIAD
CLOCK
MONO/ COLOUR CARD
MULTI I/O
512K RAM
$395
640K RAM TURBO
COMPATIBLE
COMPUTER
T
)
R
2 a
IRON EGA COLOUR
MONITORS
100 PAGE
PORT SERIAL
VGA 256K.
VGA 512K.
4
Check these features and our
prices. Wire sun you'll agree
they're exceptional value for
money!
Final assembling and testing
in Australia!
Fast TURBO Motherboard
Ar style keyboard
Tested by us for 24 hours prior
to delivery!
8 Slot motherboard
12 months warranty!
150W power supply
$49
$99
$59
DIAGNOSTIC... .......... _..6750
TU./ PRINTER
$89
$89
$199
$299
Display Tube: 14 inch 90`
deflection dot type black
matrix. Standard persistence
phosphor.
Active Display Area:
240mm 180mm
Resolution:
64 Colour:720dots(H) a 350 lines
16 Colour:640dots(H) a 200 lines
X14527
SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE SAVE
(i.1
IBM* XT* 640K
RAM TURBO
COMPATIBLE
COMPUTER
;96
FREE
CATALOGUE
PLEASE CALL
IN AND PICK
ONE UP
1
$149
$389
The 5111.12E
L:~-
$245
$29
NEW MODEMS
full duplex data commun,e.bone uch
data Mae access, Ole servile. and
electronic mall (e.s. Au.tpc and
Keyank)
wall
direct
Final assembling and testing
In Australia!
4 MiByte Main Board, 2 M/Byte
fined
Swltchable 8410/12 MHz
1.2 MByte Floppy Disk Drive
80286 CPU
Colour Graphics Display Card
8 Slots
Floppy 6 Hard Disk Controller
Printer Card and RS232
Keyboard
200W Power Supply
Manual
6 Months Warranty
Size:
360(W) a 175(H) a 405(D)mm
Includes EGA monitor
With 20 kMayte Hard Dlak.$1,995
With 40 MBytei V.C. H.O... $2295
With 80 EA/Byte Hard Disk.$2,795
$895
Quality monitors without the
exorborsnt prIC* tag!
application that require high
BABY AT*
COMPATIBLE
COMPUTER!
2M/B RAM $1,695
IIC
&
IBM* CARDS
Colour Graphics Display Card
8 Slots
Floppy 8 Hard Disk Controller
Printer Card and RS232
Keyboard
200W Power Supply
Manual
6 Months Warranty
LED light to monitor
ideal for games or word
processing. Fits most 6502
X18164
$245
"MIDI SOFTWARE"
AVAILABLE
80286 CPU
scanning speed
Bundled with 2Son'. PC Paintbrush
Pl., DR'. Scan Utility end
Img. Toole
Dalab.w and high-l.e.l
language aupPoel
Support for oew 150 peinbr./plotbrs
Support for over 225 d,plsy adaptors
Features selectable "spring
centring" or "free floating"
MIDI INTERFACE CARD Electrical trim adjustments on
both axis. 360 degree cursor
- DS/401
control
The MIDI DS -401 Card is the PC
C14205
$39.95
standard MIDI interface that
APPLE' COMPATIBLE
runs most popular PC music
Final assembling and testing
in Australia!
4 MByte Main Board. 2 14/Byte
fined
Swltchable 4/10/12 MHz
1.2 MByte Floppy Disk Drive
Size:
360(W)
K.
$595
360K Disk Drives, Multi-
function Card, Colour Graphics,
Disk Controller, 1 Serial, Parallel
Port (Clock)
$895
WITH 20 MBYTE HARD DISK:
6 single 360K Disk Drive..$1,195
8 dual 360K Disk Drives ..81,395
WITH 40 MBYTE HARD DISK:
& single 360K V.C. H.O
$1,575
E. dual 360K V.C. H.D
$1,725
r
'
10 AMP CAR
I
'
NOISE
SUPPRESSOR
Heavy duty automotive
electrical noise filter.
Reduces alternator
whine and Impulse noise.
Well take up to 40 amps.
Used for stereos, and
equalisers, CB's, etc.
386SX 16MHz MOTHERBOARD
Supports LOTUS -INTEL MICROSOFT (UM) Expanded
Memory Spec. (EMS) version
Processor: 80386SX-16MHz
'(0/1 wait state)
Co-processor:80387SX-16
(optional)
CHIPS & TECH NEAT chipsets
(SMT) Surface Mount
Technology for chipsets 8
4.0
Supports Page Interleave
Mode using 100NS DRAM
BIOS: AMI or PHOENIX
Turbo Light and Hardware
Reset connector
Keyboard or Hardware Reset
connector
Power Good Signal on board
Baby size main board
CPU
Supports up to 2MB on board,
(Sixteen 44256 and Eight
I41256 sockets)
Three 8 BIT slots
Five 16 BIT slots
Memory Expansion Slot
Optional 2-8M8 memory card
OM
$19.95
R
$795
5% OFF
386 MAIN BOARD
Intel 80386 CPU (20 MHz)
SYDNEY
STORES
H
PRICES ON
TUESDAY
XT TURBO
MOTHERBOARD
10 MHz
SIMPLY BRING THIS AD IN WITH YOU
74 PARRAMATTA RD,
STANMORE. 2048.
(02) 519 3134
Increase the performance of you
sluggish XT approximately four
times with this super fast
motherboard.
8088-2 running et 10 MHz, no
wait state
Turbo/ Normal selectable
640K
V
Expansion slots
Channel DMA
Keyboard port
8
APPLE' COMPATIBLE
SLIMLINE DISK DRIVE
2.
Only $159
FREE PACK OF S/S DISKS
WITH EACH DRIVE!
APPLE'
DC COMPATIBLE
DISK DRIVE
(including cable
Only $169
FREE PACK OF S/S DISKS'
WITH EACH DRIVE,
.'gw... retsinaao. w.%,
X18103
Excluding RAM
$149
X18032
Socket for 60387 Math coprocessor
32 bit Memory BUS system
Built-in speaker attachment
Battery backup for CMOS
configuration table and real
time clock
Keyboard controller and
attachment
7 Channel DMA
16 Level Interrupts
3 Programmable timers
8 System expansion I/O slots:
5 with a 36 pin and a 62 pin
expansion slots / 2 with only
the 62 pin expansion slot / 1
with two 62 pin expansion
slots (32 bit BUS)
Without RAM
4
O
Including RAM
$1,195
Including 2 M/Byte RAM
X18107
$1,625
$295
X18033
BABY AT'
MOTHERBOARD
(WITHOUT MEMORY)
6/12 Me« system clock with
zero wait state. 12 MHz, 1 wait
state
80286-12 Microprocessor
Hardware end software
swlichebie
Socket for 80287 numeric data
co -processor
64K ROM
Excluding Ram
X18202
$375
Including 2M/Byte Ram
X18201
20 M/BYTE HARD DISK
Drive with controller card. IBM
compatible, 3 month warranty
only $499
X20010
40 M/BYTE VOICE COIL
HARD DISK
IBM' compatible. 28 msec
access, 3 month warranty
Phoenix BIOS or Award
8 Expansion slots
$795
With
controller.. $795
80 M/BYTE VOICE COIL
HARD DISK
IBM' compatible, 25 msec
access, 3 month warranty
Without Controller.$1.295
330 M/BYTE VOICE
COIL HARD DISK
POSTCARD
DIAGNOSTIC MODULE
Pinpointing component
problems In IBM' compatible
motherboards can take hours.
Usually the whole system has to
be working to isolate the
troubled area. But not so with
the new Postcard Diagnostic
Module. So 'no other cards ere
necessary to test a bore
motherboard.
-It now only takes seconds."
Simplified debugging for:
Field service- for on -site
repairs or maintenance
depot work
Manufacturing test- for burn
In test flaws end to do
quality control
Inspection- Postcard simplifies Incoming and outgoing
test processes on stand
X18048
542.95
544.95
5849
I/O CARD
This card Is designed for the
IBM' PC/Ar expansion slot and
includes data buffering and
address selection. The wire
wrap area features plated
through holes. Extremely useful
for R&D, it's address range Is
-5V,
-12V
0280H to 72 F7H.
fuse protection and has location
for D type 37 pin or D type 25
pin connector.
H19125
IBM' compatible. 18 msec
3 month warranty
access, ESDI,
Without controller.$2,495
286 NEAT MOTHERBOARD
Processor: 80286-12, -16MHz
or -20MHz (0/1 wall state)
Co-processor: 80287
(optional)
CHIPS 8 TECH NEAT chipsets
1-4MB dual RAM socket
1-4MB module RAM socket on
board
640KB-384KB memory
relocation
Three 8 BIT expansion slots
Five 16 BIT expansion slots
Memory expansion to 8MB
Supports EMS 4.0
Page Interleave Technology
BIOS: AMI or PHOENIX
Hardware and keyboard
swltchable Clock Speed
LED speed display
Power Good Signal on board
Baby size main board
16MHz
X18090
20MHz
X18092
$595
$795
$99
100
if MAIL
;
DID YOU KNOW THAT
ALL OUR
Cat. X19901
S14053 12W BC
S14054 18W BC
FLOURO
GLOBES!
AN EXTRA
Compatible with Apple
$34.95
534.95
534.95
PRICE BREAKTHROUGH
X18094
mi
UM INN
IBM' PC/AT' DECODED
S14049 7W BC
S14051 11W BC
S14052 15W BC
SOME AUTHORITIES IN
AMERICA NOW SUPPLY
FLOURO GLOBES FREE OF
CHARGE?
IT IS CHEAPER TO GIVE
AWAY THE GLOBES THAN
FACE THE POLLUTION
AND FINANCIAL COST TO
BUILD NEW POWER
STATIONS.
ORDER 1
HOTLINE
08 33 575
IF THE SUPPLY
AUTHORITIES RECKON
THEY CAN SAVE MONEY
THEN SO SHOULD YOU.
HOW?
EACH FLURO GLOBE
PRODUCES 5 TIMES THE
LIGHT OF A NORMAL
GLOBE. SO YOU NEED
ONLY BUY A 20 WATT
FLURO TO REPLACE THAT
100 WATT GLOBE. YOU
SAVE MONEY BY USING
POWER AT ONLY 20% OF
THE PREVIOUS RATE.
IMAGINE CUTTING YOU
LIGHTING BILL BY 80% I
THOSE CHEAP GLOBES
POP ALL THE TIME AND
THEY APPEAR TO COST
MORE EVERY TIME YOU
BUY THEM. WHEN YOU
HAVE TO CLIMB ON
CHAIRS OR UNDO
FITTINGS TO CHANGE
THEM YOU REALISE THE
COST IS NOT JUST AT THE
CHECK-OUT.
THE FLURO GLOBES LAST
AT LEAST 8 TIMES AS
LONG AS YOUR NORMAL
GLOBE, YOUR TRIPS UP
THE LADDER AND THE
CALLS FROM YOUR
CHILDREN OR ELDERLY
PARENTS WILL COME
LESS FREQUENTLY.
BUT PERHAPS THE
BIGGEST SAVINGS IS IN
OUR FUTURE. IF WE ALL
USE LESS POWER, WE
NEED DIG LESS COAL, USE
LESS WATER WASHING IT,
AND LESS ENERGY
TRANSPORTING IT AND
ULTIMATELY LESS DESTRUCTION OF OUR
ENVIRONMENT.
SO NOW YOU CAN SAVE
ON YOUR LIGHTING BILLS
AND BE LIKE EVERYONE
ELSE AND CARE A LITTLE
MORE FOR YOUR ENVIRONMENT.
TAKE YOUR STAND NOW
AND INSIST ON
FLUROGLOBES FROM ROD
IRVING AND TELL YOUR
POUTICIANS WHAT YOU
ARE DOING AND WHY.
PERHAPS THE MESSAGE
WILL GET THROUGH AND
THEY WILL ALSO SEE THE
LIGHT....
r
ROD IRVING
ELECTRONICS
All sales tax exempt orders
and wholesale inquiries to:
SYDNEY:74 Parramatta Rd.
Stanmore 2048
Phone: (02) 519 3134
Fax: (02) 519 3868
MELBOURNE:48 A'Beckett St
Phone: (03) 663 6151
NORTHCOTE:425 High St.
Phone: (03) 489 8866
MAIL ORDER 8
CORRESPONDENCE:
PO. Box 620, CLAYTON 3168
Order Hotline: 008 33 5757
(Toll free, strictly orders only)
Inquiries: (03) 543 7877
Telex: AA 151938
Fax: (03) 543 2648
RITRONICS WHOLESALE:
56 Renver Road, Clayton.
Phone:(03) 543 2166 (3 lines)
Fax: (03) 543 2648
ORDER HOTLINE
008 33 5757
(TOLL FREE)
STRICTLY ORDERS ONLY
LOCAL ORDERS 8 INQUIRES
(03) 543 7877
POSTAGE RATES:
$3.00
$3.50
$10 - $24.99
$4.50
$25 - $49.99
$6.00
$50 - $99.99
FREE
$100
The above postage rates are for
basic postage only. Road Freight,
bulky and fragile items will be
charged at different rates.
$1 - $9.99
Errors and omissions excepted.
Prices and specifications sublet,
to change.
ev PC' XT. AT. . ,g,w.0 411,M. o
nnnnn
a,,.,., Mp, i
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When
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1
Think Back...
Neville Williams
Major Edwin Howard Armstrong:
a genius who lost the will to live
-2
Although with the benefit of hindsight Armstrong's main achievements were almost certainly the
discovery of the valve oscillator and the development of the superhet, his inventive genius
didn't stop there. Another of his inventions was the super -regenerative receiver, which played a
worthwhile
though short lived
role in opening up VHF/UHF communications. He also
played a key role in the development of FM broadcasting.
-
Armstrong's next invention came
hard on the heels of the superheterodyne. Spelt nowadays without the hyphen as `superregeneration', it was patented in 1922 and described in a paper
to the Institute of Radio Engineers
-
(USA) in June of that year.
Surprisingly, I found no less than
eight articles on the subject in a bound
volume of The Australasian Wireless
Review for 1923, directed to readers
who might be inclined to try out the
new circuit.
Unfortunately, none had the advantage, like the superhet article above, of
being written by the inventor; rather by
unnamed staff members, who seemed to
be uncertain as to how the circuit was
supposed to work (see panel). Having
read through the articles, I could only
hope that they meant more to enthusiasts working with prototypes than to
someone merely reading the text, the
best part of 70 years later!
I was reminded, however, of a time
when the amateur fraternity
myself
included
was probing the VHF and
UHF spectrum using simple modulated oscillator transmitters and superregenerative receivers.
Although brief, the literature from
that period was somewhat more enlightening.
It was pointed out that superregeneration could be regarded as a potential
elaboration of any regenerative detector, capable of sustained oscillation at
the required signal frequency.
It involved the addition of an external
oscillator, which could modulate the
grid and/or anode voltage of the detector so that its signal frequency oscillation would be interrupted at a suitable
supersonic frequency. A simpler alternative was to choose the value of the
grid capacitor and resistor to achieve an
artificially long time constant, so that
the grid would `block' or `squegg' at a
supersonic frequency when oscillating,
thereby functioning as a `self-quenched'
superregenerative detector.
-
rr
tl
From the June '23 Issue of 'Australasian Wireless Review' Howard Armstrong
is pictured In the formal role of inventor and academic, demonstrating his
superregenerative receiver. Contrary to some reports, he always regarded the
superhet as the more elegant approach.
32
ELECTRONICS Australia, August 1990
-
Basic principle
The accepted, if rather superficial, ex -
planation of how the circuit worked
started from the premise that when an
ordinary regenerative detector went into
oscillation, its operating point (or bias)
shifted in such a way that extra positive
feedback did not further increase detection efficiency. As well, the audible
beat note between the incoming and
local signal corrupted the modulation.
In a superregenerative receiver, the
detector effectively 'sampled' the incoming signal at a supersonic rate with high
but with less effect
positive feedback
providing a substantial
on efficiency
increase in sensitivity and obviating the
audible heterodyne.
Even so, the superregenerative circuit
had a few problems of its own: the need
for special components to generate the
quench signal, and then to filter it out
to prevent overload effects in the audio
amplifier; uncertainty about circuit adjustment and behaviour; high noise
level in the absence of signal; poor selectivity; and a tendency to radiate
noise interference into nearby receivers.
According to Electronics Weekly
Armstrong sold rights to the circuit to
RCA for $200,0011 plus 60,000 shares,
most of which was absorbed by Armstrong's on -going litigation. For RCA,
the `superregen' circuit proved of little
commercial value, although it was used
from the 1930s onwards by amateur
operators for simple receivers, and by
modellers for radio control purposes.
Readers may be interested in a quote
-
a
c
6oQ00
06006
áe
ao
-IINIi
s
-
Fig.3: The 3 -valve superregenerative circuit selected for construction and test
by The Australasian Wireless Review' in 1923. On the left is the regenerative
detector using a variometer for adjustable reaction. The quench oscillator
(centre) feeds its signal to the detector grid. On the right is an audio amplifier
stage. All valves are UV-291 tungsten filament triodes.
from the ARRL Handbook for 1936:
The student of the subject anxious to
have a more thorough knowledge of
theoretical considerations might well
study the excellent technical treatment by
Ataka in the August 1935 issue of 'The
Proceedings of the Institute of Radio Engineers' (USA).
I have not seen it personally.
Frequency modulation
With his wide-ranging background,
Armstrong was well aware of the problem posed by atmospheric and manmade interference. As far back as 1914,
Hassles with home -built superregen receivers:
The following are a few snippets from 1923 issues of The Australasian
Wireless Review, which could hardly have been reassuring to would-be
constructors:
March, p.19: Many thousands of American amateurs are working hard to
master the intricacies of the superregenerative circuit and it is hoped that
Australian amateurs will not lag far behind in bringing the circuit into
successful operation here.
April, p.22: Apparently it is only a matter of patience and experiment to get
the circuit working correctly, as every change reveals some new feature of
the circuit that seems to bring one nearer the goal.
April, p.22: The word 'roar' very appropriately describes the noise heard, as
it is as loud as the safety valve of a steam engine blowing off. It convinces
one that there is tremendous power in the circuit, if it can only be brought
under control.
April, p.27: When the two valves are oscillating, the movement of any of the
variable elements should produce a series of heterodynes or harmonics.
Unless these are heard, there is something wrong and no progress can be
made.
June, 0.26: It will be noted that long ebonite handles control the moving
elements, with the object of overcoming body capacity effect, which
experiments with the Armstrong superregenerative circuit prove to be very
great.
August, p.40: We have a good deal to learn about it yet to get maximum
results, but we are satisfied in having, at last, made the Armstrong Super
work.
he had studied it in collaboration with
Professor Pupin, but by 1922 both had
accepted that sensitivity to interference
was intrinsic to any receiver required to
respond to variations in the amplitude
of incoming signals.
So, while other engineers and experi-
menters continued vainly to dream
about anti -static measures, Armstrong
turned his attention to the possibility of
a system which would depend on frequency modulation of the carrier wave
a method which would allow the receiver to be so designed that it would
specifically reject amplitude modulation,
and therefore noise interference as well.
Frequency modulation had been a
long-time option, and Armstrong never
claimed to have originated the idea. In
his book Radio Telephony (Wireless
Press Inc, 1918), Alfred N. Goldsmith
PhD mentions FM, but discards it. But
with other engineers rejecting it as impractical, Armstrong set about to
winning, this
demonstrate otherwise
time, the backing of GE (the General
Electric Co, of Schenectady, USA).
As mentioned in earlier articles about
Raymond Allsop and FM broadcasting
in Australia, Armstrong's early research
culminated in a paper published in May
1936 in The Proceedings of the IRE
(USA), entitled 'A method of reducing
disturbances in radio signalling by a system of frequency modulation'.
His claims were supported by an impressive practical presentation to the
Radio Club of America, in the Pupin
an
Hall of the Columbia University
audience and a locale richly reminiscent
of other days. The source of the signals
was a 2kW RCA -built transmitter atop
the Empire State building. Supporting
papers were also delivered by Messrs
Weir, Flyer and Worcester of GE.
-
-
-
ELECTRONICS Australia, August 1990
33
WHEN I THINK BACK
sir
_,
(Above). Headlined as 'The first Armstrong Super to work
in Sydney' this superregenerative receiver was
constructed by Mr Fry of the Universal Electric Company
of 244 Pitt St, Sydney. Readers wanting to buy similar
parts to those used were invited to contact the above
company.
(Left).
When
Armstrong
demonstrated
.the
superregenerative receiver at Columbia University, the
audience crowded around the display.
FM broadcasting
tory prototype.
Another picture shows Armstrong
Within three years, Armstrong's
dream was well on the way to becoming swinging in a boatswain's chair 400ft
(120m) up on W2XMN's transmitting
a reality. In April 1939, under the headtower, adjusting the VHF antenna eleing 'At Long Last
STATIC-FREE
ments and cable feed system. Occupying
RADIO', the US magazine Radio -Craft
several hours a day, spread over 2
carried an announcement by Armstrong
months, this was described as the most
that the world's first static -free broaddifficult part of the whole project.
cast station was currently being set up
The development of FM broadcasting
as a personal investment.
was interrupted by the war, however,
To be known as W2XMN, the station
with Armstrong granting free use of his
would be classified by the FCC as exmany patents to the US Government
perimental, but would hopefully be
and diverting his immediate attention to
granted a commercial licence if it
military radar.
proved successful. It would transmit
After the war, FM broadcasting
from atop the Palisades (New Jersey)
emerged as an outstanding success,
near the George Washington bridge, on
spreading across America and into Eua wavelength of about 7 metres
rope and other technologically advanced
(40MHz) and would serve an area of
nations
to the dismay of established
about 100 miles (160km) diameter. It
AM commercial broadcasters. Millions
would broadcast programs originated by
of FM receivers have been built and
New York's hifi AM station WQXR,
sold around the world, virtually every
until such times that WQXR had inone of them a superhet!
stalled its own FM outlet.
In the meantime, according to the article, two experimental FM stations High personal cost
were already in operation
one in AlFrom amateur to academic, as an inbany, NY, operated by GE and another
novator, inventor and visionary, Edwin
installed by the Connecticut State ColHoward Armstrong must rate among
lege at Storrs, Conn. Six other experi- the all-time greats in the history of
mental stations were being set up else- radio and electronics technology.
where by engineers who believed that
But at a personal level, his dedication
FM had great potential.
and his unwillingness ever to let go'
GE, said the article, had begun manu- cost him dearly. He supported his confacturing FM receivers and Edwin Armvictions passionately and, when faced
strong is pictured with GE's Dr W.R.G.
with litigation, he drained his emotional
Baker checking out an 11 -tube labora- and financial resources to defend what
-
-
-
34
ELECTRONICS Australia, August 1990
he saw as principles. Although in no
sense a recluse, his preoccupation with
technical and business problems created
a work overload, robbed him of relaxation and undermined his health.
The British pioneer, Captain H.J.
Round was to say later: "Howard tried
to do it all himself and it was too much
even for his great intellect and personal-
ity."
Marconi's biographer, David Gunstan, adds the remark that Armstrong
developed "an almost paranoid conviction that he was the victim of conspiracy".
His career ended on January 13, 1954,
exactly 41 years to the day in 1913 when
the 22 -year old graduate of Columbia
University had some circuit diagrams
witnessed by a notary public.
Having written a letter to his wife,
Edwin Howard Armstrong put on his
hat, overcoat and gloves as if to go out
for the evening. But instead, say the reports, he climbed through his 13th -story
apartment window and crashed to his
death on a third floor terrace. There his
body remained until someone noticed it
mid -morning the next day.
From Electronics Weekly I borrow
this fitting tribute:
So passed from the scene a brilliant,
controversial, inventive genius of whom
it was said: the radio art owes more than
to any other one man. Today there is no
radio system anywhere in the world that
does not use his ideas in some way.
GD
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- Part 6
Basic Electronics
apacitors
The capacitor, next to the resistor, is the_most commonly used component in electronics. In this
chapter we examine the humble capacitor and show some of its many uses.
by PETER PHILLIPS
In the last chapter, we introduced capacitance as an electrical quantity. It
was seen that a capacitor is simply two
conductors separated by an insulator;
and that despite this, a capacitor can
conduct an alternating current. Interesting when you think about it: here we
have a current apparently flowing
through an insulator!
Of course, actual electrons don't pass
rather the voltthrough the insulator
age across the capacitor produces an
electric field which causes electrons to
be attracted or repelled from each
plate. The plates simply store the electrons, and the larger the plate area the
greater the capacitance. Also, the thinner the insulator or dielectric, the
greater the flow of electrons, proving
that the thinner the dielectric, the
higher the capacitance.
So how are capacitors constructed?
How thin can the dielectric be made?
And what materials are the plates made
of? There are lots of different construction techniques, giving lots of different'
types of capacitors. That's our main
topic in this chapter, along with a few
mathematical facts about capacitance.
As well, we look at combining a resistor
and a capacitor to produce a timing circuit. Yes! Some electronics at last...
Jrá
i
-
1
Capacitance
/
A
'
;
t
f
hI'
.
Capacitors come in all shapes and sizes as shown in this photo. The top row
are all ceramic types and the second row are metallised polyester. The
Styroseal type is shown on the right, (third row from top), with another
beneath it. The three capacitors next to the one cent piece are monolithic
types (sky caps). The centre capacitor of these three has the same
capacitance as the large flat film capacitor above the one cent piece.
36
need first to look at another term,
called the coulomb, which is a unit of
electrical charge.
A coulomb is
1'¡
r
The unit of capacitance is the farad,
in recognition of Michael Faraday, the
English scientist whose work we have
already referred to in previous chapters.
To explain the unit of capacitance, we
ELECTRONICS Australia. August 1990
-
a
quantity of electrons
6.25 x 1018 of them to be precise,
which is a lot of electrons. The electron
is the smallest unit of electrical charge
that can exist singly, and one electron
has a charge of 0.16 x l0-1" coulombs.
Current, as we've already explained is a
flow of electrons, and one ampere is defined as 6.25 x 10' electrons flowing
past a given point every second. In
other words, one ampere is a flow of
one coulomb per second.
You might wonder how this was all
worked out in the first place, as electrons are too small to actually count.
The credit goes to Robert Millikan
(1868-1953), an American physicist who
received a Nobel prize in physics for the
experiments he conducted around 1908
to 1917 to determine the charge of an
electron. Briefly, Millikan used vaporised droplets of oil that were sprayed
from an atomiser. He measured the
charge received by the drops as a result
of friction, by balancing the gravitational force against an electrical force
that could be measured very precisely.
From these experiments, he found the
smallest charge received by the droplets
to be 0.16 x 1018 coulombs, and the
next higher charge to be 0.32 x 1018 followed by 0.48 x 10i8 coulombs. He
concluded that as the higher values
were all multiples of the smallest value,
the basic unit of charge, due to a single
electron was 0.16 x 1018 coulombs.
From this, one coulomb is determined
by taking the reciprocal of 0.16 x 1018
which gives the value of 6.25 x 10i8
electrons. Clever stuff!
Of course, gathering an electrical
charge together requires setting up a
potential difference, or voltage. So a
charge in motion is current, and a
charge that is stored (and therefore
static) produces a voltage. Now, returning to capacitance, we can put this all
together.
In the last chapter we explained that
if a capacitor is connected to a DC voltage, a charge current will flow. Once
charged, the capacitor will have a voltage across it.
The relationship is simply this: if a capacitor (C) takes a charge of one coulomb (Q)
-
which is a charging current
of 1 amp for 1 second, and it is left with
a potential difference (V) of 1 volt, then
the capacitor has a capacitance of 1
farad.
That is, C = QN
The farad is a very large unit of capacitance, and most practical capacitance values range from millionths of a
farad to billionths of a farad. Putting
this into scientific notation, the usual
values of capacitance are the micro farad, written as uF and expressed mathematically as 106 farads; and the pico farad, (pF = 1012 farads).
It is unusual to have capacitance
values greater than 10,000uF and
smaller than 1pF. Typical maximum
values are 1000uF, (sometimes called a
11
.1210
2504AC ®
50Hz 1É
,
All the capacitors in this photo have the same value of 0.1uF. The large
capacitor at the bottom has a rated working voltage of 1kV, and the two
above it are designed to work across the 240V mains.
millifarad) and the more common
values range around fractions of a microfarad. Another way of expressing
fractions of a microfarad is with the
term nanofarad. The nanofarad (nF)
equals 109 farads, and is roughly midway between the pF and the uF.
So that's the story on the unit of capacitance. To help readers relate the
various multipliers used in capacitance
values, we have reprinted a Reference
Notebook on capacitors that appeared
in the January 1989 edition of EA If
multipliers are still troubling you, you
might like to refer back to the second
part of this series, which was published
in February 1990.
.
Capacitor types
So far we have explained quite a lot
about capacitors. We've seen that they
have reactance (previous chapter), that
they pass AC but block DC, and now
you also know about the farad. But how
are they made? Good question, and one
we can now explore.
Like most electronic components,
there are several other characteristics
about a capacitor, apart from the actual
capacitance value that need to be considered. For example, we've shown that
a charged capacitor will have a voltage
across it. But what is the limit to this
voltage? As well, the stability of the capacitance value with ageing and temperature change is an important characteristic. Then comes the physical size of
the component.
Another important consideration,
particularly if the capacitor is to be used
ELECTRONICS Australia, August 1990
37
f
Basic Electronics
1
CERAMIC DISC
FOILS EXTEND OPPOSITE
ENDS FOR CONNECTIONS
SILVER VAPOUR
SILVER VAPOUR
PROTECTIVE INSULATION
PIGTAILS
Fig.1: A foil type capacitor is made with interleaved
layers of metal foil and a dielectric. Plastic films are
commonly used as the dielectric such as in the popular
`green -cap' which uses a metallised polyester film.
with high frequencies, is the inductance
of the capacitor's connection leads and
plate.
Because all these characteristics are
difficult to address in any one type,
there are a wide variety of capacitors
made, all with their own particular qualities. Here's a brief look at some of the
types available.
Plastic -film capacitors
The basic construction of a plastic film type of capacitor is shown in Fig.l.
Here two layers of metal foil are interleaved with some form of dielectric (insulating) sheet, and wound up into a
roll. Because the foils are wound into a
tubular form, inductance will occur.
This is minimised by arranging the foils
so that one foil projects to the left and
the other to the right. The connection
to each foil is then taken from the
projecting ends, rather than simply connecting to the outer end of each foil.
Nowadays the dielectric for this type
of construction is usually a plastic film,
such as Mylar or polyester, replacing
the paper dielectric that was used before the development of plastic films.
The popular `green cap' uses a metallised polyester film. Polyester capacitors
are generally available in sizes ranging
from 1nF (0.001uF) to luF, and have
working voltages of 100V or more.
They have good temperature stability,
and reasonably low inductance. They
are used in many areas of electronics,
including audio systems, computers,
radio and TV sets.
Another plastic -film capacitor is the
Styroseal' type, which uses a polystyrene dielectric. These capacitors feature
very low leakage, but are generally
more expensive (and larger) than the
polyester types.
Mains -rated capacitors (250V AC)
38
The ceramic capacitor has a thin ceramic
dielectric that is coated either side with silver metal
vapourised
onto the ceramic. The temperature
coefficient of a ceramic capacitor depends on the type
of ceramic material used.
Fig.2:
generally use a polycarbonate dielectric
that `repairs' itself. For this reason, if a
capacitor is to be connected across the
240V mains, it is important to use a
mains -rated type, rather than one with a
DC voltage rating, even if the rating is
very high (630V or more).
Ceramic capacitors
The disc ceramic capacitor construction is shown in Fig.2, although ceramic
capacitors come in a range of shapes
other than in disc form as shown in the
photographs. In this type, silver is
vapourised onto both sides of the
ceramic material, giving a capacitor that
features small size for large capacitance
values, due to the wafer thin ceramic dielectric. The whole assembly is then
covered with a protective insulation,
which helps support the 'pigtail' connection leads.
The type of ceramic determines the
capacitor's temperature coefficient, or
the amount by which the capacitance
value changes per C°. Different ceramics are made that exhibit varying degrees of positive, negative or zero coefficients.
Some ceramic capacitors are made to
withstand high voltages, but most are
low voltage, high capacity types. As
well, most small value capacitors (lpF
to 820pF) are ceramic types, because of
the low inductance inherent in the construction. Ceramic capacitors are use in
digital circuits and radio/TV tuning applications.
The monolithic capacitor is another
small size per unit of capacitance type,
and is often classified as a ceramic capacitor.
Electrolytics
All of the construction types described so far are for values of around
ELECTRONICS Australia, August 1990
5uF or less. Electrolytic capacitors use a
chemical (aluminium oxide) for the dielectric, which allows a molecular thin
layer, giving much higher capacities for
a given size. Because the electrolyte
forms the dielectric, these types of capacitors are polarised, meaning they
must be connected with regard to the
polarity of the DC voltage in the circuit.
As a general rule, the aluminium can
is the negative end, although electrolytic
capacitors are always marked to indicate
the polarity. If the capacitor is connected with the wrong polarity the insulating layer will turn into a conductor,
which not only reduces the capacitance,
but allows the capacitor to conduct DC.
This will cause the capacitor to heat up,
and possibly explode. There are many
tales of servicemen being hit in the face
by an exploding electrolytic, so be careful!
Electrolytic capacitors range in size
from luF to 10,000uF and more. They
usually have a voltage rating marked on
the can, and this value can vary from
25V ,to several hundred volts. Most
types are either 25V or 63V rated, and
the higher the voltage the larger the capacitor for a given size of capacitance.
Electrolytic capacitors generally have a
relatively high leakage, (the RBLL
types have a lower leakage) and are
used in low frequency applications, such
as in power supplies and audio amplifiers.
The tantalum capacitor is an electrolytic type, but one that uses a tantalum
dioxide dielectric, giving extremely low
leakage and a very small size for a given
capacitance. These types are more expensive than conventional electrolytics,
and are more prone to exploding if connected with the incorrect polarity. They
are used where low leakage and high
stability is required.
Another rather interesting polarised
capacitor is the so called 'super cap'.
These capacitors feature incredible capacity for a small size, and values of 1
farad (yes, a farad, or a million microfarads) are available. These types are
used in specialised applications, particularly as a backup voltage supply in a
computer memory circuit. They are
fairly expensive and only operate at low
voltages.
Variable capacitors
Variable capacitors are used to tune a
resonant circuit, and most radios use a
variable capacitor driven by the tuning
knob or dial as the means of tuning into
a station.
The construction of a typical variable
capacitor is shown in Fig.3, in which
vanes attached to a shaft are interleaved
with fixed vanes. Older style variable
capacitors used air as the dielectric, and
-
.47+10
z50VAC®
50Hz Ti=
Fig.3: A variable capacitor such as
that used in a radio is constructed as
depicted
in (a). Normally an
insulating washer, made of plastic is
interleaved between the plates,
giving a much smaller construction
compared to one with air as the
dielectric. The symbol of a variable
capacitor is shown in (b).
Capacitors come in a range
of styles, such as those
shown in this photo. The
capacitor at the top Is
designed for use with a
mains appliance, such as a
motor, and the one beneath
it has a rating of 20kV. The
Capacitors grouped next to
the 2 cent piece are all
'super caps'. The capacitor
on the right has a
capacitance of 1 farad, with
a working voltage of 5.5V.
a bent vane would result in a short circuit. Today's types have a thin layer of
plastic (Mylar or similar) between the
vanes, which allows a much smaller size
as the plates can be closer together.
Often, one assembly may contain several variable capacitors all operated
from the same shaft, but for use in different parts of a circuit. These are generally called 'ganged' capacitors.
Another type of variable capacitor is
the trimmer capacitor, which is adjustable with a screwdriver. The construction of one type of trimmer is shown in
Fig.4, in which one plate is a layer of
metal oxide on the ceramic body of the
unit, and the variable plate, separated
with a Mylar washer attaches to the adjustable shaft.
Most variable capacitors have a relatively small value of maximum capacitance, typically around 10pF to 100pF,
and the adjustable vanes are usual)
connected to the common (or earth
line of the circuit.
Fig.4: A trimmer capacitor requires
adjustment with a screwdriver, and
most are designed to mount directly
onto a PCB. The construction of a
typical trimmer capacitor is shown in
(a), and the symbol is shown in (b).
(a)
(b)
Fig.5: Capacitor packages are usually
the axial style as shown in (a) or the
PCB mount type depicted in (b).
Package styles
Capacitors are available in several
package styles, but the two most common are the axial lead type and the
PCB mount type, depicted in Fig.5. Another type is the can type, which may
contain several individual capacitors all
sharing a common terminal. There are
other less common types, such as those
designed to fit under an IC, and special
ELECTRONICS Australia, August 1990
39
Basic Electronics
4 0V
high voltage types.
4 0V
Most capacitors have the capacitance
value marked on the case, although
Philips and other makers sometimes use
a colour code. Capacitor values generally follow the same set of preferred
values that apply to resistors, in which
multiples of 1, 1.2, 1.5, 1.8, 2.2, 2.7,
3.3, 3.9, 4.7, 5.6, 6.8 and 8.2 are used.
Thus it is common to find a 0.56uF capacitor, but uncommon to find a 0.5uF
value.
Some manufacturers label the value in
picofarads, assigning a numerical value
for the number of zeros. For example, a
capacitor whose value code is 104 is
equal to 100,000pF (10 with with four
zeros). To convert this value to uF,
move the decimal point back six places,
giving 0.luF. Similarly, the value 563
decodes to 0.056uF, or 56nF.
600ytF
560QuF:
LNA
ELNA
h
5
EM
0
rao
*4.w ,
.
!
Combining capacitors
When capacitors are connected to-
gether, the total value of capacitance
that results will depend on how they are
connected. There are two basic ways of
connecting any electronic component: in
series (or end to end) and parallel (or
side by side).
The schematic diagram of Fig.6(a)
shows three capacitors connected in
series and (b) illustrates an analogy in
which, effectively, the dielectric increases in thickness. Because the dielectric is `thicker', the overall capacitance
of the combination is now less than the
i
1---I1_
(a)
C
l:2
cH3
(b)
II--(c)
III
T
(d)
T T
_L_
Fig.6: (a) shows the schematic
three
capacitors
of
diagram
connected in series. The effect is to
increase the thickness of the
dielectric, as Illustrated in (b). This
gives a smaller total capacitance, but
a higher overall working voltage.
Connecting capacitors in parallel (c)
has the effect of increasing the total
plate area as in (d), resulting in a
total capacitance that equals the sum
of the individual values.
40
This photo shows various electrolytic capacitors. The group of three at the
bottom right are tantalum types, and the three on the left in the second row
from the bottom all have the same value, but different working voltages.
smallest single value in the combination.
The equation to calculate the total ca-
pacitance of series connected capacitors
is identical to that used to determine
the total resistance of parallel connected
resistors, and equals 1/(1/Cl + 1/C2 +
1/C3 ...).
Capacitors are often connected in
series to give a higher working voltage.
For example, if a luF, 600V rated capacitor is required but is unavailable,
three 3uF, 200V capacitors can be connected in series as a substitute. When
connecting capacitors in series to share
the working voltage, it is important to
realise that the voltage will be distributed inversely to the capacitance. If a
luF and a 2uF capacitor are connected
in series across a 300V supply, the luF
ELECTRONICS Australia, August 1990
will have 200V across it and the 2uF
will have 100V across it.
Capacitors are connected in parallel
to increase the total capacitance.
Fig.6(c) shows the schematic of three
parallel connected capacitors, and (d)
shows an analogous effect in which the
total area of the plates has increased.
The total capacitance of parallel connected capacitors is simply the sum of
the individual values.
It is a fairly common practice to connect capacitors in parallel, usually to
obtain a larger value than available singly or to distribute the capacitance. In a
large printed circuit board such as a
computer, designers often place capacitors around the board, but show them
as parallel connected capacitors on the
constants along the horizontal axis.
A time constant is defined as the time
taken for a capacitor in a series connected RC circuit to charge to 63% of
the applied voltage. It is calculated by
100
96%
90
eº%----
80
--
(b)
simply multiplying the individual values
of the resistor and the capacitor. That
is, TC = RC
an easy one to remember. For example, if a resistor of 100k
ohms is connected in series with a 0.luF
capacitor, the time constant of the circuit equals 100k times 0.luF. This calculates to 0.01 seconds, or 10 milliseconds.
If a voltage of 10V is applied to the
circuit of Fig.7(b), then for the values
just stated, it will take exactly 10 milliseconds for the voltage across the capacitor to reach 6.3V. This is shown on
the time constant curve, where one time
constant intersects with the value of
63% of the final voltage.
If you study the curve, you will see
that it takes two time constants for the
voltage to reach 86%, and that after
five time constants, the voltage across
the capacitor is virtually equal to the
applied voltage. Theoretically, the capacitor will never charge to the applied
70
63,/o
60
30
I
I
I
I
I
I
I
I
07
(a)
T
_t_
20
10
I
-
C
R
1
2
6
3
TIME IN TIME CONSTANTS
11 TIME CONSTANT o
RxC)
Fig.7: (a) shows the universal time constant curve for an RC circuit, and (b)
the circui that applies to this curve. A similar curve, but. drawn upside down
from top left to bottom right) is used to describe how a capacitor discharges
through a resistor.
circuit diagram. For example, if four
0.1uF capacitors are shown in parallel
on the circuit diagram, you might think
that one, 0.4uF capacitor would do instead. But no! On the printed circuit
board, the four capacitors will be
spaced around the board. This is done
because the PCB tracks have inductance, (inductance was discussed in the
last chapter), and by physically spacing
the capacitors this prevents the inductance of the tracks from affecting operation.
Capacitors can also be connected in
series/parallel, to give a combination of
increased capacitance and working voltage. A point to always watch when connecting electrolytic capacitors is the polarity of the individual capacitors. In
series, the positive terminal of one connects to the negative of the next, while
in parallel the positives are all connected together and the same with the
negatives.
Now that we have discussed capacitors fully, let's put them to use in a simple timing circuit.
the individual values of the components
used in the circuit. This graph is referred to as the universal time constant
curve and is calibrated in percent of
final voltage (vertical axis) and in time
TABLE 1: SUMMARY OF EQUATIONS FOR CAPACITORS
Capacitors in series:
CT
-+
C2
1
+
C3
C2
or for two capacitors:
for
N
CT
Cl
C2
+
capacitors of the same value (C) in series:
C
CT
N
Capacitors in parallel:
Charge in
a
capacitor:
CT
Q
=
=
Cl
+
C2 + C3 +
CV
where:
The RC circuit
A common use for a capacitor is to
provide a time delay. In fact, most timing circuits use a capacitor in conjunction with a resistor. To explain the principle, we need to introduce a new term,
called a time constant.
When a capacitor is charged via a
resistor, as shown in Fig.7(b), the voltage across the capacitor will rise as
shown by the graph in (a). This graph is
a most important representation, as it
describes all resistive/capacitive (RC)
circuits. Note that it does not include
1
Q=
c=
V
Capacitive reactance:
=
charge in coulombs
capacitance in farads
voltage in volts
1
XC
=
2nfC
where:
XC
=
=
Time constant:
TC
=
C
=
TC
=
R
=
C
=
capacitive reactance in ohms
frequency in Hz
capacitance in farads
R xC
where
time constant in seconds
resistance In ohms
capacitance in farads
ELECTRONICS Australia, August 1990
41
CAPACITOR
I
MARKING CODES
EA Reference Notebook
Solid Tantalum colour coding
TENS
Capacity in uF
Colour
Dome
1.
black
brown
red
orange
yellow
digit
Ring
2
2oled_
0
e
1
1
1
a
10
'--'-9
4
Colour
----3
2
a 100
4
-
green
blue
5
5
6
6
violet
7
C.
voltage
Voltage
multiplier
marking of
2
wrote
digit
_Rated d.
Dot
white
3V
_yellow
6.3 V
-
8
8
a
9
9
a
black
10V
green
16 V
blue
gray
pink
20 V
25 V
35 V
.
0.01
0.1
UNITS
BLACK
BROWN
0
0
1
1
RED
2
2
ORANGE
YELLOW
3
3
4
4
GREEN
BLUE
5
6
5
6
VIOLET
7
7
GREY
8
WHITE
GOLD
SILVER
9
8
9
-
-
MULTIPLIER
TOLERANCE
1
100
200
300
-
1000
10000
100000
-0 +100%
1000000
--
400
500
600
700
8o0
900
1000
2000
-
0.1
0.01
-
-
20% (M)
1%(F)
2% (G)
10
100
-
VOLTAGE
5% (J)
10% (K)
Marking of capacity: colour dot indicates the polarity orientation according to drawing
Reproduced from the ITT Components data sheet for "TAG"
capacitors, courtesy Standard Telephones & Cables Ltd
IEC marking code
Miniature ceramic capacitors and small polyester film capacitors are
often marked according to the IEC marking code, where space would
not permit the value in pF and other data to be given in full. Briefly,
the IEC rode is as follows. The first and second digits are the first and
473
SJ
The international colour code is used to indicate the value and
other characteristics of resistors, capacitors, and other components. Various arrangements, differing slightly from that
shown, are used by individual manufacturers. (The letters in
the tolerance column are sometimes used in place of colours.)
Resistance values are in ohms and, unless otherwise specified,
capacitor values in pF. As indicated in the ceramic code
(below) the tolerance on capacitance values equal to ór less
than 10pF are often quoted in pF rather .than percentage.
Values greater than 10pF are quoted in percentage.
Ceramic colour code
K,00
second significant figures of the value in pF, while the third digit is
the multiplier in terms of powers of 10. Any alphabetic letters following
0.25pF.
indicate tolerance, i.e., M is 20%, K is 10%, is 5%, C is +
Further figures indicate working voltage.
temperature
firm
co./rtnen,
Digit
/-
1
red/violet
PIUO
black
N PO
brown
NO33
Temperature coefficient
red
orange
NO73
2
2
NISO
3
3
Miniature ceramic capacitors are manufactured with various temperature coefficients of capacitance-i.e., they exhibit different degrees of
capacitance change with temperature. Type N750 (violet colour code)
has 750ppm°C negative coefficient; type NPO (black colour code) has
less than 3Oppm°C, either polarity. These are the two most common
yellow
14220
4
4
green
N330
N470
5
5
blue
6
6
violet
14750
7
7
VeY
white
orange/orange
8
a
9
9
N1500
types.
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1st figure of capacitance
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1
10
0.1
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10'
10'
±0.25
'
10
10
22
±0.5
t5
t
10
V
2nd figure of capacitance Yalu.
multiplying factor
capacitance tolerance
working voltage
body colour
Flee cede
colour code for
-
temp. coefficient.
lee Table above
sy
<olour
* 70e/
o
black
brown
10
red
orange
2
2
10-
3
3
10'
yellow
6
4
10.
green
blue
6
6
violet
grey
7
7
wham
9
250V
60ov
10'
630V
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v
*10%
capacitance
value in pF.
using K for
the thousands
cad, for loleutu r
On eapact ante: (.0
tot
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pt
,yd,
1141
0.25
0.5
42
ELECTRONICS Australia, August 1990
1/1
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The drawings above and to the right are reproduced by courtesy of Elcoma. (Philips Industries Ltd.)
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led
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211.50
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Basic Electronics
For Features and
Performance...
INPUT
OUTPUT
r\r"
(a)
R
INPUT
TC
OUTPUT
o
Fig.8: An RC
circuit such as
that shown in
(b) can be used
to change the
shape (and the
sound) of a
formwave, as in
(1). Note how
the waveform is
rounded with a
shape following
that of the time
constant curve
in Fig.7.
Gótia Gatta
GoldStar
I
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s,:. ... ,.- i ,.
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Prices
include
(b)
TWO
xl/x10
voltage, but we can regard 99% as close enough. In fact, you
can use this curve to determine the voltage across the capacitor for any time interval. For example, after 0.7 time constants (i.e., 7 milliseconds for our example) the capacitor will
be charged to half the applied voltage.
Now let's say you want a circuit that gives a delay of one
second.
Using the equation of TC = RC you can see that there are
infinite number of values that will give a time constant of
one second. If we pick a resistor of 1 megohm, then a capacitor of luF will give the required time constant of one
second. If we apply 10V to this circuit, it will now take one
second before the voltage across the capacitor has reached
6.3V.
To make a timer, all that is now needed is a circuit that
triggers when the input voltage reaches 6.3V.
In future chapters we will show how this can be achieved,
but now you know the basic principle of a timing circuit.
Another use of an RC circuit is to modify a waveform.
Most sound systems have a bass and treble control, and the
actual controls are usually variable resistors in conjunction
with capacitors. The circuit is often quite complex, although
the basic circuit of Fig.8(b) will act as a treble cut (or bass
boost) control.
The waveforms shown in Fig.8(a) illustrate how a square
wave is affected by the circuit of (b).
Note how the output waveform has a shape like that of the
time constant curve, but one that charges and then discharges for each half of the input cycle.
The effect is that the sound will be smoother, with the high
frequencies removed, much like operating a treble cut control on an amplifier.
an
In conclusion
Over the last six chapters we have examined the three fundamental electrical quantities of voltage, current and resistance.
As well, the three main passive components used in electronics (resistor, inductor and capacitor) have been described, along with some basic maths that describe their behavious.
A summary of all the equations we have described that involve capacitors is shown in Table 1.
Next month we will examine the diode and Start looking at
some actual electronic circuits that you can actually build.
switch
probes
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Macelec (042) 29 1455
5177
D.G.E. Systems (049) 691625
W.F.Dixon (049) 69
Newtek (042) 271620
Novacastrian Electronic Supply
(¡049) 62 1358.Obiat Pty Ltd 698 4776
Geoff Wood 4271676
Digitel 709 6511
N.TERRITORY J Blackwood (089) 84 4255, 521788
Thew & McCann (089) 84 4999
The
B.A.S. Audiotronics 844 7566
QUEENSLAND St Lucia Electronics 252 7466
Electronics Shop (075) 32 3632
Xanthos Electrical
Solex (Townsville)(077) 72 4466
(079) 27 8952
S.AUSTRALIA Elmeasco (08) 344 9000
VICTORIA G.B. Telespares 328 4301
The Electronic Components Shop 670 6474
Factory Controls (052) 78 8222
Mektronics Co 587 3888
Truscott Electronics 7213094
W AUSTRALIA Atkins Carlyle 481 1233
Leda Electronics 361 7821
NEW
42
PAPUA
6246
GUINEA T E (P.N.G.) Pt Moresby 25 6322 Lae
READER INFO NO. 7
SHORTWAVE
LISTENING
by Arthur Cushen
«lawla"e
Greenwich discontinues
time service to BBC
For 75 years, the Greenwich Observatory has provided the
world with time. pips, but the BBC has now taken over the
function of providing a world time service.
The change took place recently, when
the pips were transmitted from the basement of the BBC's Broadcasting House
in London rather than being relayed to
the radio over landlines from the Royal
Greenwich Observatory in Herstmonceux, southern England. The new signal
is accurate to within one millisecond
compared to a five millisecond delay in
the old pips, which had to travel along
160km of landline.
The BBC is basing its time on a combination of sources, following a decision
by the Royal Greenwich Observatory
that astronomy and the measurement of
the earth's rotation is no longer part of
its work. In the basement of Broadcasting House, four clocks are linked by
radio and satellite to international atomic
time standards.
For listeners to the World Service of
the BBC, there is a problem. Checks
have shown that time pips transmitted
direct from London are received a split
second before those which are carried
by a BBC transmitter at a relay base,
AROUND THE WORLD
ALASKA: KNLS' schedule has been reduced to 10 hours a day, to allow for upgrading of equipment and the introduction of automation. This reduced English schedule,
effective for several months, is 0800-0900 and 1500-1600 on 11715kHz. English is
not broadcast on Monday 1500-16000TC, being replaced by Asian languages.
BELGIUM: BRT Brussels has retimed its service to Australia and now carries English
0630-0700 on 6035, 11695 and 13675kHz; the service to North America is 23302400 on 11695 and 13675kHz.
HOLLAND: Radio Nederland now broadcasts in English to Australia and New Zealand 0730-0825 on 9630 and 9715kHz, the latter replacing 15560kHz. The broadcast from 1030-1125 remains on 11890kHz. In the Thursday transmission the feature
programme is 'Media Network', an electronic magazine for the shortwave listener.
SAN MARINO: A new country for shortwave listeners is projected, with the move by
Adventist World Radio from their present Forli site in Italy to San Marino. The new
facility will replace the existing lease -term arrangements from Radio Trans Europe in
Portugal, as well as the church -owned 5kW shortwave station at Forli in Italy. It will
complement the coverage of AWR Asia from a 40 hectare site, with studios in San
Marino. Two shortwave transmitters are proposed, of 100kW and 250kW. The first
stage of the project will include building four antennas, consisting of three log -periodic antennas and one curtain array. A further curtain antenna is planned. Initially
one transmitter will drive any of the log -periodic antennas, and up to three more
transmitters could be added when funds become available. It is expected that the
new station will be operational within two years.
SWEDEN: Radio Sweden is to reduce its language broadcasts, particularly in French,
Spanish and Portuguese, and increase transmissions to Eastern Europe. Priority is to
be given to the Russian, German and English broadcasts which will have more resources and personnel. Radio Sweden has made some changes in its transmissions to
Australia and New Zealand; English is now broadcast
30-1 2000TC on 17740,
21570 and 21610kHz, with a later transmission 1400-1430 on 17740 and
21610kHz. A broadcast 0230-0300 is now on 11705 and 15295kHz and this programme includes 'Sweden Calling DXers' on Wednesday.
1
44
ELECTRONICS Australia. August 1990
which receives its signal via satellite.
The time difference arises because the
signal has to travel up to the satellite and
back down to the relay base. Anyone
who has made an international telephone call will be aware of satellite links
and the problem of conversation when
there is an echo effect.
An accurate time system at the transmitting site is plamíed so that when listeners listen to the Singapore relay base
of the BBC, time pips will originate from
that site and not from London. BBC engineers are also looking at using a telephone line to the remote relay bases
overseas, which would compensate for
the time delay between them and London.
The BBC plans to keep its time pips as
accurate as those of the Royal Greenwich Observatory
at least within one
-
millisecond.
I
r
1
Headquarters of the Red Cross
Broadcasting Service in Geneva,
Switzerland.
Red Cross tests
The International
Committee of the
Red Cross in Geneva, Switzerland, is to
conduct another series of tests using the
facilities of the Swiss Broadcasting Cor-
ofirs
ELECT
poration. The ICRC began broadcasting
during the final days of World War II,
when they transmitted lists of prisoners
awaiting repatriation, and of missing
people.
In 1948, the ICRC was granted the use
of a frequency in time of major crisis,
and began test transmissions. It uses a
recording studio and broadcasting facilities in Geneva which are given free of
charge by the Swiss PTT and Swiss
Radio International.
The programmes are in English,
French, German, Spanish, Portuguese
and Arabic and contain news of Red
Cross action around the world.
The Red Cross Broadcasting Service
has listeners in every continent and welcomes reports, comments and questions
to 19 Avenue De La Paix, Geneva, Switzerland. An IRC is appreciated, and reports and confirmed by QSL cards.
The International Red Cross test broadcasts were scheduled for Mondays, June
25, July 30, August 27, and for Thursdays, June 28, August 2 and August 30,
at 0740-0757UTC on 9560, 13685,
17670 and 21695kHz.
CD
THE JOB IJITH H FUTURE
This column is contributed by Arthur
Cushen, 212 Earn St, Invercargill, New
Zealand, who would be pleased to supply additional information on medium
and shortwave listening. All times are
Be prepared for the future.
quoted in UTC (GMT), which is 10
hours behind Australian Eastern Standard Time.
>t1Ih0ÍI1IINl
1990 I
=
I
11ílUU
t1995
J1995
._
,
rJ
P
4
Electronics is one of the fast-growing fields of employment.
So
if you are interested, Stott's have a home study course
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Choose from a range of Electronics Courses.
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READER
ialFO NO. 27
PHONE
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New Zealand, Box No. 30-990, Lower Hutt, Tel:
676592,
.
I
The
0000
viceman
Enough! Enough! He cried
at least until the morrow...
OI
-
Readers have responded well to our appeal for contributions. now have enough material for
several months of 'Serviceman' stories, to supplement those from my own workshop. I have
three stories, plus a rather amusing
four items from contributors for you this month, in fact
ditty that should strike a few familiar chords.
I
-
The first two tales come from the
same reader, L.D. of Elizabeth in South
Australia. Both stories are linked by a
common theme, so I'll let L.D. tell the
story in his own words:
Sometimes it appears that if you know
the difference between a resistor and a
capacitor, you can get the reputation of
being an electronics whizz and this can
drop you into some seemingly awkward
situations. ESPECIALLY so if an acquaintance asks you to "Please, just
have a look at it for me, and give your
opinion."
Two such incidents occurred a few
months ago and rather than stumping
me, as I feared they might from the initial stories, they actually enhanced my
'electronic whiz' reputation.
The first was when a friend brought in
what looked like a car distributor, with
the complaint that "the motor wouldn't
go". I knew that he was reasonably good
at repairing cars and was surprised that
Cut The
Guesswork!
SADELTA TC400
Television signal
level meter.
Ask your aerial
supplier for
a brochure
today!
1!
Mel
I
.
.
-
Peter C. Lacey Services Pty. Ltd.
Fax:03 787 3460
74 Fulton Rd. Mt. Eliza 3930
READER INFO NO. 8
ELECTRONICS Australia, August 1990
The story on the intermittent operation
was another problem, but after discussing it we decided that it was probably
heat sensitive: if parked for a few hours
in the shade the car would start and run
for a short time on a hot day, and
longer on a cool one.
A quick check with the CRO showed
that the unit would give out pulses on all
four leads when +I2V and earth were
connected and the shaft rotated. But as
do not have a four-trace CRO, I could
tell nothing about the phase relationship
of these pulses. It could be done, laboriously, with the dual -trace CRO and I
mentally worked out how to do that
- -
-
-
Under
$700+tax
46
-
he would ask me about a distributor
until he opened it.
Rather than being the 'old' familiar
system of breaker points etc., it had an
optical disc which interrupted the light
from an IR LED to a photodetector
which in turn was connected to a circuit
board with three or four transistors, an
IC and a few other discrete components.
What these components were was not obvious, as the board was potted in what
looked like a solid lump of shellac, with
the components barely visible inside.
I was reluctant to even attempt to look
at it, knowing how awkward it is to get
at potted circuits, but after hearing his
story, I decided to have a quick look
at his risk.
Basically, the story was that the car engine would sometimes refuse to operate,
and he had traced the trouble to the distributor by the simple expedient of borrowing a good one from a friend's car.
The big problem came when he tried to
buy a new circuit card or a replacement
unit. New circuit boards were not available; it was either a complete new unit or
nothing, and a new unit would cost him
$600 plus!
He was able to supply me with a circuit diagram, made in the usual motor
manual fashion of 'connect the red wire
with the white stripe to the terminal
marked B'. This was not a lot of help,
but he had traced which wire was the
chassis connection and which was the
+I2V lead so at least I had a starting
point.
Another four wires went to a black
box ín the engine compartment. I had no
idea what this black box did, but I reasoned that the unit in hand must send
some pulses to it. And as the distributor
was either operating properly or not at
ll, then if I could detect any pulses
coming from it they would probably be
the right ones.
later, if necessary.
The next step was to check for sensitivity to heat. This was easy. I simply
used a hot air gun to heat the unit, while
retesting it (holding it in rag this time to
avoid burning my hands!)
Success! Not a pulse on any line! After
allowing it to cool again it worked as it
had initially.
The next problem was more perplexing
how to get through the potting to find
the faulty component? I was able to cut
off some small pieces, as it was rubbery
rather than solid, and tried various solvents on them.
Luckily, a rather safe solvent, methylated spirit, did the trick so / left the circuit board soaking in a bath of metho
after removing it from the distributor. It
took a day before I was able to safely
peel and rub off the gunk to see what the
components were.
(As an aside, the gunk was not fully
dissolved, and after the methylated spirit
had dried out it reset. I used this phenomenon later on to replace the potting,
to protect the unit for return to service.)
Checking the board after removal from
the unit posed a problem, as l could no
longer turn the shaft to rotate the optical
disc. However, I found I could simulate
-
the effect by passing a piece of paper
through the gap where the disc normally
ran.
A combination heat -gun and freezer
Flipping pic
their heads.
Now, it's possible to make a picture
turn upside down. All that is necessary
is to reverse the leads to the vertical
winding on the yoke. This will invert
the picture, but will not alter the left-to right orientation.
To change up -down AND left -right,
the leads to both horizontal and vertical
yoke windings have to be reversed.
Quite clearly, this is not something that
can happen spontaneously!
The customer was asked to bring in
the television set so that it could be
tested thoroughly. It turned out to be
not a 'television set' at all, but a video
monitor
a professional grade monochrome monitor from a CCTV system.
On the bench, hooked up to a good
video camera, the monitor produced a
first class picture with no sign of any instability, either horizontal or vertical.
This seemed to point to the CCTV
camera as the culprit in the case. In due
course it was delivered to the workshop
and connected to the monitor, in the
same configuration as in the customer's
premises.
The camera was soon confirmed as
the villain, when the picture started flipping over top to bottom. What's more,
it was also flipping side to side. In other
words, a complete 180" rotation.
As mentioned, there's no easy way to
achieve this rotation. And there's no
conceivable way it could happen by accident. At least, not with any conventional camera and monitor setup. But
this camera was not quite conventional
- at least among cameras common up
to the present time. It's likely to become the conventional model from now
on, as you will see.
The CCTV camera was not a vidicon
tube type, but one of the latest CCDsensor solid state cameras. And its output was not the usual analog signal produced by scanning the target with an
electron beam guided by scanning coils.
It was a pseudo -digital signal, clocked
out of the CCD sensor array by digital
Anyway, now on to the third story
for this month. It comes from S.McB.
of Townsville in Queensland, who reminds us that the practise of electronics
but
can involve all sorts of disciplines
rarely does the service technician need a
knowledge of optics to solve his problems. Read on, for a short lesson in
photography as well as electronics servicing...
It seems that S.McB. has a customer
who complained that the picture on his
`TV' kept turning itself 'upside down'.
One minute the people were right side
up, next minute they were standing on
type shift registers.
(I have read eight different explanations of how the output of a CCD chip
is produced and really, I am none the
wiser. In precise detail, it is a very complicated process. It's best to simply accept that an IC controls the CCD and
the output is composite video!)
In the problem facing S.McB., it
seemed that the shift registers were running forward one minute, then backward the next - clearly a ridiculous
idea. But there was no other explanation!
In the end it was a chance observation
spray treatment with judicious shielding
of components narrowed the problem
down to a plastic encapsulated transistor,
and I breathed a sigh of relief.
Why relief? Well none of the transistors or the IC had any markings on
them! I was relieved that it wasn't the
IC, as trying to work out its characteristics and find a replacement would have
been a very tedious job.
As I read L.D's story, I found myself
getting quite hot under the collar. The
first story, about the $600 car part repaired with a 30c transistor, made me as
mad as the proverbial meat axe.
It reminded me of the $1200 engine
management computer board shown to
me by my local service station proprietor recently. The board contained no
more than $20 worth of parts, but could
not be repaired because all part numbers had been removed by the manufacturer. And of course, there was no circuit diagram or service manual.
New cars are getting more and more
expensive, so that only the well-to-do
can afford them. And the less wealthy
will be denied useful second-hand vehicles, because of the exorbitant prices demanded for replacement electronics.
Doesn't it seem stupid, that at a time
when electronic products are getting
cheaper every day, automotive electronics are getting more expensive - and
being deliberately designed to prevent
easy servicing!
Then L.D.'s second story, about the
`white thingummy' is just as disheartening.
Luckily, this customer knew
enough and had the gumption to take
the argument right back to the retailer.
How many other customers would have
simply shrugged, bought a new $350
controller and silently cursed the manufacturer instead of the retailer?
-
-
that provided the clue that solved the
problem.
The camera was dis-embowelled and
spread out, still operating, on the
bench. Discrete prodding and poking
revealed that the fault was mechanical,
and responded to pressure near a particular jumper wire adjacent to the control
IC.
Reference to the circuit diagram
showed this jumper to be connected to
a pin on the IC marked 'lens', and further reference to the service manual resolved the whole dilemma.
The manual explained that the Lens
pin should be grounded for use with a
'normal' lens, or open for a 'terrestrial'
lens. With this, all became clear!
Most camera lenses produce an inverted image on the film (or vidicon or
CCD). This is normal and has been
taken for granted by photographers for
about 150 years. (I spent some years as
a photographer, and in those days I
would have given anything for a switch
that could erect the image on the
groundglass of my studio camera!)
In the same way, astronomers have
always accepted that their telescopic
images of the heavens have to be inverted to make them agree with naked
eye sightings.
On the other hand, birdwatchers and
yachtsmen would not accept an inverted
image. Terrestrial telescopes and binoculars have to have an erecting lens included in their construction, to allow
the user to see things 'right way up'.
Some camera lenses have also been
made with this erecting lens,built in, to
enable the lens to function as either a
camera lens or a telescope.
In a normal film camera, it doesn't
matter which way up the image lies. If a
terrestrial lens records a picture upside
down, the final print can easily be
turned up the other way.
So that was the function of the
jumper in the camera before S.McB. It
was intended to invert the image if the
camera was fitted with an erecting lens.
Quite simply, the jumper lead had become dry jointed, and was flipping the
shift register between the upright and
inverted modes.
To our knowledge, this provision (for
inverting the image) has never been
made on a video camera before, hence
the hours of confusion that led up the
solving of the problem.
S.McB. gave me this story as an
aside, while discussing another matter.
I've repeated it here to alert readers to
the fact that you really have to he the
full bottle on all manner of subjects, to
stay ahead of modern electronics!
ELECTRONICS Australia, August 1990
47
cess water bill. She opened the bottom of
the case, which comes off to gain access
THE SERVICEMAN
to the terminals, and pointed to the 'IC'.
I recognised it immediately as a 5" watt
resistor! Luckily it was not black, but
just badly burned and I could read the
value as 4.7 ohms. (It also measured 4.7
ohms on the meter, but I later replaced it
as it had obviously been badly overheat-
ed.)
i
e/
At least the transistors were obviously
simple switches, being connected between
the +12V rail and ground
with the
bases fed from the IC and the outputs
going to the output terminals where I
had measured the pulses.
Finding a replacement was not hard.
The, collector resistor value indicated a
maximum current of about 15mA
through the transistor, so I chose a
BC548 and wired it in place. Then I
tested the unit for heat sensitivity. With
the problem now seemingly solved, I replaced the potting compound, assembled
the unit, tested and returned it to the
owner.
As I said, that was several months
ago, and the car has been running without missing a beat since then; so I can
chalk that one up as solved.
The second case followed about a
month later, and although there was
nothing technically difficult about this
one either, it also involved saving considerable money for the customer.
(It is nice to have really grateful customers who are willing and even anxious
to pay more than the job is worth, just
because you were able to do something
for them that they had thought impossible.)
This case concerned an automatic
home watering system, installed about
four years previously. It belonged to a
very capable and enthusiastic lady gardener, and had been working perfectly
-
48
until about three weeks before she saw
me.
It was summer and she was going
away for a few weeks holiday. Naturally,
she did not want her lawns and garden
to suffer during her absence, but the
sprinkler controller had blown a fuse.
She looked at the blown fuse and
bought a replacement, but although the
replacement fuse did not blow, the unit
started issuing smoke and a white 'thin gummy' had turned black.
She called in the expert (salesman?)
from the company which had installed
the system, and after looking at it he told
her that the 'thingummy' was a special
integrated circuit, no longer available,
and that she would have to get a new
unit. This was, of course, an updated
version and would cost $350.
As her holiday budget was fully committed, she could not spare $350 just at
that time. She was in a quandary, and
came to me asking "would I please have
a quick look at it, to see if something
could be jury-rigged to keep it going for
a while?"
I imagined that the 'white thingummy'
was one of those welded-in ceramic IC's,
and I expressed some doubts about the
possibility of making a repair. But eventually I agreed to give my opinion.
The next day she arrived with the unit.
This was a rather fancy box, with a liquid crystal display and push buttons to
set just about everything except the ex -
ELECTRONICS Australia. August 1990
I then checked out the timer and found
that it was sending 24V to the correct
output terminals at the right times, and
in fact seemed to be working perfectly.
The burnt resistor had me worried
though, so I traced the circuit involving
it. It was connected in series with the
common output terminal, acting as a
current limiter while the other terminals
were connected to drive transistors.
On a hunch, I checked the fuse. 10
amps? 4.7 ohms by 5 watts gives one
amp! When I asked her about this, she
went a little red in the face and replied
that the blown fuse had a 10 on it and
she hadn't looked for a decimal point!
(In fairness to the lady though, despite
the fact that she repairs her own electrical appliances and also makes many mechanical repairs to other items, she generally avoids electronics as 'too complex', and had never encountered fuses
as small as one amp.)
This suggested a likely answer to the
problem. I asked her to check the resistance of the solenoids which turn the
water on and off. She has her own multimeter and is quite capable of using it.
Next day she reported that one was
reading about 2 ohms while the others
were all nearer 200. She had disconnected the faulty solenoid and the system
was now working, with all but one spray
point. After returning from holidays she
replaced the faulty solenoid valve and
the system was fully operational again.
As a matter of interest, she can be a
very hard lady to deal with, especially if
anyone is not honest with her, and she
proved it again in this case.
She had been charged a 'service fee' by
the company for the initial call -out and
had paid it. But after replacing the unit
and finding it to be working, she went to
see the manager and not only got her
service fee refunded but also demanded,
and got, a replacement solenoid valve to
compensate her for the trouble that they
had caused her.
Technically, neither of these cases required any particular genius, but both
were items that I had never encountered
before. In addition, both of the problems
came to me as a 'last resort' after all the
normal avenues had been explored.
In retrospect, the faults and diagnostic
methods were much the same as for any
radio or TV set. More importantly, it
was the clues provided by talking with
the customer which really solved the
problems in both cases.
That repair you really should've dumped
again lands at your door.
The customer is all upset.
starts laying down the law.
Electronic muse
"You've scratched
And finally, a bit of poetry to lighten
the tone of this month's column. It was
contributed by L.F., of Woodville Gardens S.A., and although it's a bit out of
our usual style, it seemed just too good
to keep to ourselves. L.F. calls it:
LIFE IN THE DAY
OF A SERVICEMAN!
Who was the clever person
who said you never can
'Please all the people all the time'
was he a Service man?
-
Years in the industry have proved
that statement to be true.
I wonder if the scenes to come
strike a similar chord in you.
A customer comes in and plonks
his set up on the bench.
"It's never been no good" he says
in English laced with French.
'I could 'ave fixed it up meself,
but i've no time at present.'
You weakly smile and nod your head,
and try hard to be pleasant.
-
Then when it's fixed he must donate
a little of his wealth.
"WHAT? 60 bucks to change a part
I could've changed meself?"
But what's the use of trying to
explain the hours it took
a leg, mislaid a knob,
and knocked a plastic trim".
"The picture's now too bright!" he adds,
you can't say that of him!
So in conclusion let me say,
they've all been through our door.
A lady brings a Walkman in and asks
"Please can you fix it?"
You get the feeling that her son
occasionally kicks it.
No wonder that a serviceman's
invariably poor!
The lid is broken, cabinet's cracked,
the headphones are in tatters,
but fixing up his pride and joy
to her is all that matters.
A worried lady then rings in,
with a voice that's very faint.
It seems she has a microwave
and this is her complaint.
Her food is getting far too hot
and starting to turn brown
"Would it be right for me to use"
'DEFROST' to cool it down?"
But if you think these stories are
not true, I ask you then
to notice all the nodding heads
my fellow service men!
-
And I nodded along with the rest of
them! Thanks L.F., I think we all enjoyed that.
That's all for this month. There are
more contributions to come, and some
more stories from my own bench. Stay
tuned!
-
Then there's the chap who loves to tell
that he knows how to solder,
and thinks he's being helpful
looking over your left shoulder.
He also asks a million questions,
trying to make you nervous.
It's all a part of being a tech
when you're on outside service.
But, customers help pay the bills.
What would you do without 'em?
find the leaky diode, when
he KNOWS that you're a crook?
-
They make us prematurely gray,
well as quicken pulses,
and give us headaches, blood pressure,
and duodenal ulcers.
as
-
to
The phone rings half a dozen times,
you think you'll go insane,
from video enquiries you're
expected to explain.
"I think I've got it now, but could
you tell me just once more
what is that button labelled
'video -antenna' for?"
Arid yes, of course, they're always right.
How could we ever doubt 'em?
/4
Fault of the Month
Sony KV-1830AS
(Early version, before S/N 300.001)
SYMPTOM: No pix until set thor
-
oughly warmed up
about 1(
minutes. Luminance could be forces
through by raising screen voltage
but there was no sign of colour.
CURE: Fault turned out to be an inductor in the collector of the 7.8kH2
amplifier transistor, Q309. The coil
was open circuit when cold, but
came good as it warmed up. (The
fault explains the `no colour', but not
the `no luminance', thus making a
very confusing problem.)
This information is supplied by courtesy of the Tasmanian Branch of The
Electronic Technicians' Institute of
Australia (TETIA).
Contributions
should be sent to J. Lawler, 16 Adina
Street, Geilston Bay, Tasmania 7015.
Then there's the set that must be fixed
with lightning haste and speed.
The customer puts on an act
that makes your poor heart bleed.
You push it through in record time
because you feel you must.
It's been repaired for six weeks now,
and sits collecting dust...
Another chap comes in with
a CB, wet and salty.
He's not sure why it doesn't work
but says
I think it's faulty!"
"-
Then adds this gem to just make sure
his story you believe:
"I'm not sure if it won't transmit,
or
if it won't
receive!"
ELECTRONICS Australia, August 1990
49
Has our author developed
The 'ultimate'
loudspeaker leads?
In a rare blend of illogicality and commonsensical electronic
doubletalk, the author tells a story of one audiophile's foray
even negative
into the nether world of zero impedance
resistance speaker leads. Read on, and see if you can spot
anything wrong with his reasoning...
-
by BRYAN MAHER
While the editor's not looking, let me
tell you about my latest invention, perfect loudspeaker leads!
You can forget all that nonsense you
have been reading about oxygen -free
copper or liquid mercury conductors.
They only tried to reduce the speaker
lead resistance. The fantastic approach
described herein does a lot more than
it reduces the speaker lead
that
resistance right down to zero!
This of course means that the damping factor on speaker cone movement is
dramatically increased, so your pride and -joy speakers will (believe it or not)
have even less distortion. To the very
bones!
You perhaps define damping factor as
the speaker impedance divided by the
driving impedance. That driving impedance (i.e., the amplifier output impedance plus speaker lead impedance) becomes the damping load, which prevents the speaker cone moving under
momentum. Such free wheeling by the
cone generates nasty sounds, which you
wish would go away - distortions which
you need like a hole in the head!
The lower the driving impedance, the
more heavily the speaker cone is
damped, constraining it like a tempestuous child on a leash and gently persuading the cone to faithfully follow the
music signal from your expensive amplifier.
Now the salesman, who gently levered
your life savings from you for said amplifier, probably spun a glossy yarn
about its low output impedance. waving
in the air before your glazed eyes a colourful brochure quoting 'Amplifier output resistance equals 0.1)02 ohms!'
-
50
You recall how you spontaneously
jumped for joy, scaring the devil out of
your sultry spouse as you mentally calculated a speaker damping factor of 8
ohms divided by 0.002 ohms equals
that's more damping fac4000! Wow
tor than that insufferable next door
neighbour, whose damping factor is a
mere 400!
So gleefully handing over aforesaid
life savings, you rush home with new
amplifier under one arm and a fistful of
loudspeaker leads gratuitously bestowed
upon you ás an enticement by the same
errant salesman your doubting spouse
and whimpering bairns trailing behind
like a string of pearls.
But the sound emerging from your
speakers was still distorted as before,
with consequent unenthusiastic response
from your wiser spouse.
-
-
The sad truth
In the still of the night, as you lay
counting sheep, the truth suddenly
dawned upon your exhausted brain
cells.
Of course - the amplifier output
resistance (0.002 ohms) is as nothing
compared to the resistance of those
skinny little copper leads the man so
generously threw in for free.
Fig.1: How to use
superconducting
metal tubing (A)
for speaker leads.
Tubing B is
plastic hose.
ELECTRONICS Australia. August 1990
You bound out of bed, oblivious of
the crying kids and howling dog you
woke in your haste. Must measure those
speaker leads! Ripping them unceremoniously from the audio system, your
trusty ohm -meter blinks
then tells
you that those scrawny leads measure
no less than 0.48 ohms!
That in series with the amplifier output resistance is of course 0.482 ohms.
So your speaker damping factor is still 8
ohms divided by 0.482 ohms, equalling
a very poor value of 16.6. No better
than before, in fact.
Dejected, disgusted and muttering
agonized comments unprintable in this
magazine you stumble off to bed. That
salesman!
But no, it's not his fault! There's
you
nothing wrong with the amplifier
just need speaker leads with zero resistance.
A small voice in the back of your
mind keep insisting that all connecting
wires have some resistance. But perhaps
there is a way...
-
-
Super solution
Simple! You just need superconductive loudspeaker leads.
No problem - just race down to your
nearest hardware store, buy some copper tube plated with niobium -aluminium -germanium alloy. Make up two
speaker leads from said exotic tubing,
attaching plastic hose to each end as in
Fig.1, so you can pump liquid helium
continually through the copper tubes.
This will cool the niobium -aluminium germanium alloy down to superconduct-
temperature, below 20 Kelvins
(-253°C).
Some of the conduction electrons in
the niobium will associate in pairs and
short out all the resistance, leaving you
with a loudspeaker source resistance of
only the amplifier's output resistance, a
tiny 0.002 ohms. Hence you will at last
achieve a beautifully high damping factor of 4000 as aforesaid!
In eager anticipation, you search
through your suburban hardware stores
and even undertake a foray into the
city. But in no shop can you buy a refrigerator capable of cooling helium gas
to such a low temperature. Nor any
other gas for that matter! Anyhow,
most other gases would solidify before
they got that cold.
Desperate, you feverishly scan the
newspapers. But instead of ads for
super -cold refrigerators, you spy an article about new developments in superconducting ceramics, at temperatures
you would call cool, not cold (only
about 70K, or - 200°C). Lovely
must
buy some!
But these materials are so brittle that
they cannot be bent to shape, much less
hooked around amplifier terminals...
Defeat! Dejection! Oh woe are you!
It is beyond the pale! While you bemoan your misfortune, your other half
patiently yearns for better music production.
But all is not lost. You idly pick up a
book on electronics, and in its golden
pages you learn the fascinating secrets
of feedback.
No, not the cheeky feedback you get
from your offspring, nor the dry wit of
your (usually) supportive spouse.
ing
-
Magical feedback
We're talking here of negative feedback, that wonder of electronics, which
can provide for your loudspeaker leads
having zero effective resistance. Well
almost. And at ordinary room temperatures, too!
How? Simple - the idea is made
clear by the diagram of Fig.3, wherein
you may see that negative feedback is
taken, not (as you might expect) from
the amplifier output terminals, but
rather from the loudspeaker terminals.
It's called (for want of a better name)
'remote feedback'.
Yes, there still are voltage drops
along those loudspeaker leads, but such
voltage drops are part of the feedback
signal, so are compensated for by the
amplifier's open loop gain. Input signal
between A and B is amplified by the
amplifier's open loop gain to produce
amplified voltage and power at C and
-
FEEDBACK PATH
A
SIG
i
a
Fig.2: Normal negative feedback is
taken from the amplifier"s output
terminals.
D, in the usual way. But the difference
in this circuit lies in the fact that the
negative feedback derives from the
speaker terminals E and F.
We use ordinary copper speaker
leads, with their usual impurities of oxygen, arsenic, sulphur, etc
albeit in
microscopically small percentages). The
normal resistive voltage drops reduce
the feedback signal and as the effective
voltage amplified by the open loop gain
equals the input minus the feedback,
more signal is amplified, effectively
compensating for the speaker lead voltage drop. This mechanism causes the
very low output impedance (0.002
ohms) of the amplifier to be felt right at
the speaker terminals, as if the speaker
leads had zero resistance.
Success! The system damping factor
returns to 4000 overall! Not only does
remote feedback remove the resistance
of your speaker leads, it also reduces
drastically the inductance effects those
leads have on your audio signal. That's
even better still!
Admittedly our audiophile had some
trouble with his amplifier oscillating
under remote feedback (due to speaker
lead inductance), but with a little help
from generous
electronics friends
(fiends?), that little problem was unceremoniously conquered.
-
Better still?
But wouldn't it be nice to be even
better still? Lest it be murmured among
readers that our friendly (though often
misguided) audiophile is greedy, objectionable and socially unacceptable in aspiring to further improvement, let us
hasten to recant that wise old adage:
'The world is advanced only by dissatisfied people'.
AMPLIF It -t
OUTPUT
RESISTANCE
IS
GL
THE
SPEAKER
DAMPING
RESISTANCE
[.
'RÓ A,,
AND
v0
tA.
Fig.4: Deriving an equivalent circuit
for the amplifier and speaker system.
SPEAR
_FADS
AMPLIFIE
Fig.3: Remote feedback is more
effective, although a little tricky.
Let us try to see how that magic
damping factor could be improved even
more. But how? Consider the fundamental equivalent circuit of Fig.4, showing Ro, the amplifier output resistance
which in turn damps the speaker; Cl,
L1 and G2 the electrical analogs of the
speaker's cone mass, inertia, suspension
spring constants and stiffness, and R1
the ordinary voice coil electrical resistance.
Observe that Ro and R1 are simply in
series, as combined electrical damping.
To make even heavier damping we need
the resistance value (Ro + R1) to be
less. But using Fig.3 we have Ro down
to 0.002 ohms, with R1 about 8 ohms.
So (Ro + RI) = 8.002 ohms.
How can that value be reduced? We
certainly cannot change Rl, for that is
inside the speaker. Any significant reduction of (Ro + RI) could only be
achieved by making Ro negative.
What
you want Ro to be a negative
resistance? Crazy! Impossible!
-
Negative resistance
But wait! It's true that no physical
resistor can have a negative value, but
the marvels of electronic negative feedback can bring about a negative value
of output resistance Ro. Yes, it's true!
Fig.5 shows a proposed scheme where
Ro is the amplifier output resistance, Si
is the real loudspeaker and S2 is a
group of electrical components electromechanically equivalent to the loudspeaker Si. Remote feedback is derived
from G and H.
The amplifier thinks it's driving two
parallel identical speakers, except that
R3 is in series with S2. Now R3 will
cause a voltage drop, so that for full signal to appear at the feedback terminals
G -H it must be that at full current the
signal voltage between E and F is
;ligher than that between G and H. But
at no current the voltage E -F is the
same as at G -H.
Now just wait a cotton-picking
minute! That statement is saying that
the voltage E -F increases, as current is
drawn from the system - not decreases.
as you'd expect for a normal system
Continued on page /44
ELECTRONICS Australia. August 1990
51
-
r
hardware
we are over-stocked...these lines must be cleared!
NUT & BOLT PACKS
Cat H-1000
6BA $1.95
Cat H-1010
4BA 450
BA TYPE
TERMINAL BLOCK
TRANSISTOR
MOUNTING KITS
Cat H-6741
TO -220 TYPE MICA
$295
WASHER AND BUSH
Pack Cat
Price
Size
12mm x 4BA 10 H-1032 $1.50
20 H-1332 1.85
4BA nut
(brass)
50 H-1488 1.45
4BA washer
(steel)
50 H-1486 1.95
4BA S -Proof
washer
12mm x 6BA 25 H-1092 3.95
bolt (brass)
25 H-1342 1.85
6BA nut
(brass)
6BA Pack - 12 x 12mm bolts,
brass nuts, and washers
PCB
NUTS AND BOLTS
Cat H-1916
RUBBER GROMETS
Pack of 5
51.50
9mm HEX. 4BA
TAPPED SPACERS
Cat H-1842
6pk
Pack Cat No Price
Pk
No
H-1712 $1.95
10
2.25
H-1716
10
2.50
H-1719
8
Hole
Size
8mm
12mm
16mm
$250
RIGHT ANGLE
BRACKETS
Cat
100
Cat H-1990
100 x 2.3mm
Cat H-1992
(with ID tags)
100 x 2.3mm
Screw on
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Large square
H-1736 $2 95
H-1740 1.50
H-1745 1.95
H-1749 2.50
nMICA
Q
Cat H-1684
0
$1295
$1395
1495
995
4BA tap
O-
H-1843
12mm
6
4
H-1847
25mm
Type: Insulated
$3.95
4.50
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10mm
15mm
20mm
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5
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141861
H-1862
H-1871
H-1872
-
NYLON NUTS
AND BOLTS
$3.95
4.25
4.50
4.75
$4.95
8BA Pack 12 x 12mm brass
bolts, nuts, and
washers
Cat 11-1682
414~114
Type: Round 4BA hole
Price
Length Pack Cat
H-1831 $5.50
6mm
12
5.50
H-1832
9mm
10
5.50
H-1833
12mm
8
H-1834
5.50
25mm
6
Type: Hexagonal
CABLE TIE
PACKS
160 x 3.5mm
O
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PLATED BRASS
PCB SPACERS
45C
Cat H-1988
Pack of 4
95C
TOGGLE SWITCH
DRESS NUT
110 x 2.5mm
BUSHES
Cat H-1918
$
577 95
Cat H-1986
2
Cat H-1917
TO -3 TYPE INSULATING
Cat H-1895
OF
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$1.95
RUBBER FEET
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TO -3 TYPE MICA WASHER
$5.95
SELF -TAPPING
SCREW PACKS
d
Pack
Size
No. 4 x 12mm
size 40
No. 4 x 6mm
size 40
No.8 x 12mm
size 30
Pack Cat Price
Size
12mm x 4BA 10 H-1012 $1.75
25mm x 4BA 10 H-1022 1.95
4BA Hex nut 12 H-1302 2.75
2BA washer 12 H-1452 1.25
12mm x 6BA 10 H-1032 1.50
25mm x 6BA 10 H-1042 1.75
6BA Hex nut 12 H-1312 2.95
6BA washer 12 H-1462 1.25
DIC
No. 4 x 6mm
Cat
Price
25 H-1612 $1.50
25 H-1611
1.25
25 H-1632
1.75
500 H-1625 10.95
Bulk Pack
SWITCH -SCREWS
Cross pan -head screws to
suit most switches with
threaded mounting holes.
Cat 11-1674
Pack of 10
$120
MITH
ELEC RONICS
ha dware.
NA
cases reduced!. now every project can afford a home!
PLASTIC
van
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CASE
4e/
This new Australian designed case has
3 circuit board slots, a snap fit cover,
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dimensions are
$595
WAS
155x100x75mm.
$9.95
Cat H-2597
METAL PROJECT CASE
TOOL BOX
An attractive two-part case with
sturdy plastic tool box with two full
width trays, metal latches, and large
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ventilating side slots finished in blue
and grey. It's 160x130x5Omm and ideal
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A
Cat H-2762
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$
i 295
$49
HEATSINKS
TO -5 TYPE
ROUND
TO -3 TYPE
POWERFIN
MINI PCB
Cat H-3400
Cat H-3402
5350
5195
For the greatest possible
heat dissipation in the
smallest possible space.
Suits all flat semiconductors
and has fluted fins for
maximum thermal efficiency.
51 95
The universal hole pattern
on this Heatsink provides
mounting for nearly all
'power' semiconductors.
VERSATILE POWER
ECONOMY POWER HEATSINK
HEATSINK
Flat mounting design with fins top and
bottom. Available undrilled or pre drilled for 2 TO -3s. Measures
UNIVERSAL
HEATSINK
Cat H-3401
Measures 50x50x26mm.
SNAP-ON
HEATSI[SKS
TO -220
style
S195
Cat H-3416
TO -126 style
Cat H-3417
1 85
19
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i
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,.%>1., Cat H-3412
N
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Designed to ensure a snug
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74x102x25mm.
Mounts flat or at right angles
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78x110x33mm undrilled or
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Cat H-3460 Undrilled
Cat H-3461 Pre -drilled
5725
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MITH
ELECTRONICS
00
WITH
A 386SX FROM
0
e
e
HERE ARE
32 Bit
..
ow©,1/
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.
_
2
-
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T=^r>-fCse/ ^ f
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~m
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Their TotalCare Engineer will come to YOU and in most cases your
computer will be repaired ON THE SPOT! Your 12 Month Warranty can
become 12 months TotalCare Field Service for just $150. 24 months of
TotalCare Service can also be arranged.
-
Cat X-8240
THE PRICE
Only
$2 995
Including VGA Monochrome Monitor
Add $500 for Multi -Scanning VGA Colour Monitor
B973
i
c
K
All Superseded Stock Must Be Cleared
At Give-away Prices! -Limited Stocks!
You'll Never See Prices Like This Again!
a
Sharp Pocket Computer PC1248
8k RAM, 17k ROM
16 char. display
Built-In BASIC.
$99
Cat X-5132
Sharp Memory Expansion
Cards
Printer & Cassette Interface
Prints Thermal hard copy from your Pocket
Computer and allows you to connect a
cassette recorder for data storage. CE126p
5
Cat X-5119
Printer Paper Rolls
139
5595
Cat X-5121
Pocket Computer
EA23 Mains Adaptor CattX-512251 295
CE152 Data Cassette Recorder
Designed especially for recording
computer data.
Cat X-5139
For Cassette
Size
Price
Part
X-5136
8k RAM
$39.95
CE212M
X-5137
X-5138
16k RAM
$49.95
CE2H16M
#
32k RAM
$69.95
CE2H32M
To
suit these Pocket Computers:
o
PC 1100
o ' # PC 1360
o ' # PC 1425
o ' PC 1450
Keyboard
84 key XT style keyboard with
CE124 Cassette Interface
Connects your Data Recorder to the
Sharp Pocket Computer.
Cat.
o
o ' PC 1270
o ' # PC 1280
$99
Cat X-5140
key
high quality
ALPS
keyswitches.
$3995
CE152 Mains Ada o for cat X-514151295
Can control 2 Hard Drives and
2 360Kb or 1.2Mb 514" Drives on
your AT compatible computer.
Cat X-3578
Off The Desk
Kit
Fax Card
Send and receive Facsimiles
directly through your
computer.
Cat X-3302
XT
or Al
Includes CPU floor stand,
keyboard extension cable, and
monitor extension cable- all
you need to finally get your
'599
Hard Disk To
$99 Video
Tape
Floppy Disk
Backup Card
Controller
With this card you can
Cat X-2008
Controls two 360Kb or 1.2Mb
floppy drives.
Cat
X-2014o
$4995
CMS Music Card
Create 12 voice stereo music
on your IBM compatible!
Includes 32 preset Instruments,
stereo amplifier, and the
'Silpheed' game from Sierra.
Plays the music tracks included
on all the latest Sierra software
tool
Parallel Data
Booster
Break the 2 metre limit! Move
your parallel printer up to 16
metres from your computer.
Requires an AC adaptor. (not
included)
Cat X-3820
Recorder
Hard/Floppy
Disk Controller
o ' # PC 1460
o ' # PC 1475
o ' # PCE500
computer
s2995
Monitor Cable
Hard -to -get 9 pin male to
video!
8
pin
Cat X-8616
OFF THE DESKI
Cat X-3850
backup
your Hard Disk without the
expense o! a high speed tape
streamer or without taking
forever using floppy disks.
Cat X-3840
'299$249
Cat X-2020
DIC
1:7
MITH
ELECTRONICS
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NEW FOR
I
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4 Digit Capacitance Meter ccc
Use it in the workshop, use it in the laboratory. This meter can
measure capacitance from 1pf to 9999uí in seven ranges. It is mains
powered, which means a big bright LED display, and it has an
accuracy of better than +1%. Supplied complete with all components
including plastic case, deluxe pre -punched silk screened front panel,
and even alligator clips and BNC plug for test lead.
1 29
Cat K-7500
vr
Light Chaser ccc
''
Dazzle your audience with a professional looking light show! The
Light Chaser has 6 chasing patterns, 8 speeds, an enhanced
monitoring display, and the ability to run 2400 watts of lighting. It
comes with an attractive plastic case and pre -punched silk screened
front panel.
Cat K-3161
$99
Chromavox
e
QQQ
39
This handy kit is more than just a random number generator. It
displays its numbers in the traditional die format on two rows of three
LEDs. You can even see the Electronic Dice counting as numbers roll
by and stop just past that elusive six. Short form kit with all
components, PCB, IC sockets, and battery holder.
0
f
Ti1iill
Cat K-8401
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2 Sector Module 4
Expand your K-8401 Burglar Alarm Control Unit. Add as many of
these Sector Modules as you need. They hold two sectors, each with
LED status indicators and isolating switches. Kit includes
components, PCB, and IC sockets.
1 295
Cat K-8400
J
Cat K-8403
Hot Canaries c
Electronic Dice Q
o
This Control Unit features variable entry and exit delays, LED
status indicators, alarm driver circuitry, timed and latched
outputs, two separate sector inputs, and the provision to add extra
sector boards as required. This is a short form kit which includes
all components, PCB, and IC sockets.
This keypad operated combination lock could be used to operate your
K-8401 or other Burglar Alarm. Works with solenoid door locks too! It
can even be wired to trigger the alarm when the lock detects
repeatedly incorrect entries. The kit includes all components, PCB,
and high quality keypad.
Cat K-3162
Cat K-3532
Q
Combination Lock Q
Automate your light show and let it dance to the music! The
Chromavox accepts line input from an amplifier or operates
independently, off its built-in microphone. This kit comes complete
with a moulded plastic case plus pre -punched silk screened front
panel and can handle up to 2400 watts of lighting.
X1
2 Sector Burglar
Alarm Control Unit
$995
1-0
m
Put your budgies out to pasture and let these Hot Canaries rule the
roost! Intrigue your cat as these two birds sing their electric sox off.
The kit comes with a cat-proof case, PCB, all components, and front
Can- label.
Cat K-3530
a'
...o. C....,.l
$2495
o
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11/1.11-
o
Kits marked with this symbol involve mains power wiring.
Take
extreme care when working with this equipment.
Degree Of Simplicity
Q
Simple
cc
Intermediate
ccc
Detailed
ELECTRONICS
pet's Brighten
. Your
BULBS
SWITCHES
Keypad Matrix Switch
Suitable for electronic
FO D 0
locking devices or as
E
numeric input for any
digital device.
D Oe O9
S395
Cat P-7804
p ID
000L
Pigtail type neon bulb as
used in indicators, timing
circuits, oscillators, etc.
70-90 volts @ 600uA.
Cat P-8160
DPDT Lampswitch
As used in Strobes,
The double pole version of P7874. Fits the same hole but has
a slightly larger body
(23x15x13mm). Rated at 240Vac.
2A per pole.
warning lamps, and
photographic equipment.
Operates on 200-400
volts with a 4kV trigger,
and has 5 watts maximum
input.
is DPDT and
mechanically interlocked
so that only one button
can be activated at once.
Switches spaced at 11mm
centres.
Miniature Edison Screw
BULBS to suit most
illuminated dials.
Cat P-8150 6 volt
each
Cat P-8152 12 volt
50c
Cat
75c
Crocodile Battery Clip 20A red
Crocodile Battery Clip 20A black
P-7750
Single DPDT Switches to
match the 4 Way Switch
Pack
Car/Battery Clips
Battery Terminal Clip 30A red
Battery Terminal Clip 30A black
5395
3
This switch pack is ideal
for audio switching
applications. Each switch
M.E.S. Bulbs
M.E.S. bulb sockets
Cat P-8162
Cat P-8164
4 Way Switch Pack
7 5c
P-6420
P-6422
P-6416
P-6418
Cat P-7752
S1.25
S1.25
51.95
51.95
Switches1.. ..
Xenon Flashtube
.
Neon Bulb
=
5
95
Illuminated
Push Button Switches
A
square switch with round body
as used in car burglar alarms
and control panels. Uses
alternate make/break switch
action and has an inbuilt 12 volt,
55mA bulb.
Cat
Cat
Cat
Cat
P-7580
P-7582
P-7584
P-7586
LI >hi zi
+
P
II
yellow
S' 395
each
Pull on, push off single pole
switch as found controlling lights
or wipers in many older vehicles.
This switch is ideal for trucks too
as it's rated at 24 volts, 10A.
Cat P-7562
S495
The perfect replacement for a
worn out desk lamp switch. Fits
an 11mm hole and is rated at
240Vac 2A.
Intended for automotive use, the
soft glow from the toggle is not
distracting. The 12 volt lamp
operates from the supply being
switched (12 Vdc @ 16A).
5195
5425
DS XPRESS PHONE & MAILORDER SERVICE
Outside Sydney (FREE Call) 008 22 6610 Sydney And Enquiries - 888 2105
FAX: (02) 805 1986 or write to DS XPRESS, PO BOX 321 N/RYDE NSW 2113
kRIC9+.1
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24 HOUR DESPATCH OF ALL ORDERS
IJICRW
TOYS &
blue
green
12V Illuminated SPST
MITH
ID(
red
Dashboard Switch
Cat P-7666
)1
5250
Cat P-7876
SPST Lampswitch
Cat P-7874
DIC
Up ny
Z Le
.
AUDIO
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63 Stores Across Australia
That's right, the
Tandy TRS-80 model
3 is definitely NOT a
current model. But
'obsolete' models
like this can now be
picked up quite
cheaply, and are fine
for many basic
computing jobs...
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The easy way
into computers
As with cameras, new personal computer models seem to appear like clockwork every couple
of months. Whatever you buy, within a couple of years it'll be totally 'obsolete'. But just as you
can still take prize-winning pictures with an 'obsolete' camera, you can do lots of basic
computing jobs
like word processing
with a low cost 'obsolete' computer. In fact they can
make an excellent choice for your first machine, or for controlling other equipment...
-
-
by TOM
Rili
OFFAT
Love them or loathe them, computers
are part of life now, and all of us are
going to have to learn to live with them.
Some people even learn to enjoy them,
even though the computer industry
seems hell-bent on making computers as
hard to get along with as possible.
Every day we have piles of hype heaped
upon us by television, newspapers, and
magazines... "This new Brand -X makes
all other technology obsolete! So throw
out your old ways of doing things, and
58
buy Brand -X now!"
Why? I mean, why should we jump at
this `golden opportunity, too good to
miss?' What's wrong with your old computer, or your typewriter for that matter? They work, don't they? If it ain't
broke, don't fix it. Here's an example
of the pressure we face every day, for
'out with the old, in with the new':
Late last year I attended a computer
show; you know, one of those big extravaganzas in which all the swank com-
ELECTRONICS Australia, August 1990
puter companies send their identically
blue -suited and name-tagged salesmen
(whoops! sales-persons) to convince you
that your business is bound to fail unless you invest in a Brand -X computer
RIGHT NOW!
It seems that Brand-X, a well-known
multinational company, had chosen this
show to unveil its latest mega-machine
with the latest 64 -bit microprocessor
running at some outa-sight clock speed.
I had a name tag too, identifying me as
'technical writer', and I was humping
my big old camera bag around so as to
look especially important (the bag can
hold several tinnies, as well as the camera). Brand -X's State Salesmanager saw
me, and pounced.
"You've gotta do a story on this!
Writers all over Australia have been
waiting on this one, and here it is,
handed to you on a platter!" The man
was in full razzle-dazzle mode.
"Well", I said, "what can it do?"
"WHAT CAN IT DO??? Watch
this!" And with that he unleashed his
machine into a sort of slide show, with
high -resolution graphics pictures of sunrises and birds and snow-capped mountains. "That's very pretty", I said, "but
I can see sunrises and birds and snowcapped mountains by just stepping out
my back door. Why do I need a computer to show them to me?"
"Well, er, um..." (Mission Control,
we've got a problem here. This fellow is
supposed to fall down on his knees and
grovel in front of this computer, and he
isn't doing it.) So I hit Mr. Salesmanager with another one: "What does
your machine actually DO?"
"Er, aah it runs Lotus 123".
"So does my old XT" (an 'obsolete'
model PC, for the uninitiated).
"But ours is so much faster!"
a
-
"So what?"
SO WHAT??? You're not supposed
to say 'so what' at a computer show.
You're supposed to write a glowing report about how this new technology is
going to revolutionise the science of
computing, etc, etc. You know the
stuff; if you've ever read a computer
magazine, you've seen it.
So what indeed! But nowadays lots of
people are starting to say 'So what' in
the face of all the hype, and this troubles the suppliers greatly. Perhaps a
simple, cheap computer can do the job
as well as the latest rip -snorter model.
Many users are finding this to be the
case, and some of the most highly
touted software packages and operating
systems are languishing in a sea of
buyer resistance.
The computer industry at long last is
starting to get this message, and some
portions of it are now catering for the
`so what' buyer who just needs a simple
tool to do a straightforward job. So the
industry now appears to be heading in
two directions: Up, into the world of
more power, more speed, more bits,"
and more money; and sideways or
slightly downward into the world of
small, simple, and cheap.
The laptop computer is the prime example of this second line of development. The laptop 'revolution' will be
the subject of another article, but in the
meantime let's look at some other 'so
what' options
good practical computing alternatives that will do an honest
day's work for you without sending you
to the poorhouse or making you tear
out your hair in frustration.
If your work is not up in the stratospheric levels of desktop publishing or
high -end computer aided design. you
probably don't need the flash graphics
capabilities of the mega -computers. So
something like a simple PC-XT would
do, at say a tenth the price. And if you
don't need graphics at all, you could
-
^,
r
lower yourself even further to a (dare I
it..) CP/M computer. Let me explain...
say
Main uses
As a reader of Electronics Australia,
you're probably interested in using computers a bit differently from the traditional 'business' user. There are four
main areas where you're likely to use a
computer:
1. Word
processing; writing letters,
business proposals, quotes, etc.
2. Keeping records for a small business,
such as a repair shop.
3. Circuit board design.
Electronic process control, or pure
experimentation.
The fourth item, the computer as
part of some electronic device, will be
looked at in detail in a separate article.
For now let's concentrate on the first
three. All of them except circuit board
design can be done on a computer with
absolutely no graphics capabilities.
The CP/M operating system, the
world standard before the IBM-PC
came along, made for useful, even elegant computers. Only one thing was
lacking
graphics. But nobody seemed
to care; if nobody else had graphics,
you didn't need them either to 'keep up
with the Jones's'. You just got down to
the work at hand. Such as...
4.
-
Word processing
'Power' users of mega-computers can
spend hundreds, even thousands of dollars, on a word processor. These are
sometimes sold along with spreadsheets
and databases as 'integrated packages'.
Or they may be served up as 'desktop
publishing'. But the fact remains that
word processors are basically electronic
typewriters that let you make instant
corrections, shuffle blocks of text
around, store your work on disk or get
it back, and print the results on a piece
of paper.
The computer word processor is better than a typewriter only because you
can change anything you wish while
your document is still in the computer,
and commit the result to paper only
after you're sure it's perfect. You can
say goodbye to white -out bottles and retyping of pages.
The disadvantage of word processors
that they must live in relatively big
computers that plug into the wall. But
the laptop is now changing all that, and
you can have a word processor that's as
small and light as the portable typewriters of old.
Keep in mind that a word processor
is
Another 'elderly' personal computer is the App!e Ilc. pictured here with disk
drive and printer. It too is fine, for many basic jobs.
ELECTRONICS Australia. August 1990
59
Using `obsolete' personal computers...
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Two more 'obsolete' personal computers, both of which can be picked up quite cheaply on the second-hand market. At
left is the Australian -made Microbee 64, with the Commodore Vic -20 at right.
nothing more than a computer program; it certainly isn't some kind of
magic spell. It is simply a tool, and
YOU are in control of it, just like with
your electric drill. And there is one
classic word processor program that
stands out above all the others: WordStar.
Experts will tell you that WordStar is
old hat now, totally obsolete, but hundreds of thousands of people around the
world are still using it as a matter of
choice, in preference to the 'state of the
art' packages.
Even our editor Jim Rowe sits in
front of a computer running WordStar.
Every word that appears in Electronics
Australia has been through WordStar
first. I write all my material with a form
of WordStar and send it to Jim on a
disk in WordStar format. The point is
that you readers out there would never
know that this magazine was produced
with the humble WordStar, instead of
some flashy desktop publishing package.
WordStar began as a CP/M program
and made its way up through Version
3.3 by the time the IBM-PC made
CP/M unfashionable. Version 3.3 was
translated into IBM code to run on the
PC, and then 'improved' through further versions. I think it's up to Version
5 now. But each version became bigger
and more memory hungry, and the latest WordStar demands something like
two megabytes of disk space.
If you're going to get WordStar, I
think Version 3.3 is still the best choice.
The CP/M and IBM versions appear to
be identical in every way. If you can lay
your hands on a good used CP/M computer such as a Kaypro or Osborne or
is
60
Microbee, that along with WordStar 3.3
will do everything you'll ever need for
basic word processing. And if you eventually move to an IBM -style PC, you'll
find that the PC version of WordStar
3.3 is a familiar old friend. I doubt you
can even buy a new copy of WordStar
3.3 now, but there should be plenty of
them around on the used market.
Another word processing option is to
get a WordStar clone, probably as a
Shareware program. Shareware software
you pay
is virtually non-commercial
and it's very
for it if you like it
cheap. WordStar clones are available in
both CP/M and IBM formats.
I'm not actually using WordStar now,
but a clone called VDE (Video Display
Editor). You type your material into it
exactly as with the proper WordStar,
but the whole program is written in machine code so it's lightning fast. VDE
comes in both CP/M and IBM versions.
Some other Shareware word processors
can be configured to work exactly like
WordStar, and even the editor in the
Turbo Pascal language is set up to look
like WordStar. As I said, it's truly a
-
-
classic.
Record keeping
Small businesses generally need to
store information such as customer
records in some kind of orderly system
(database' is the proper term). It is also
necessary to keep financial records, so
you know where your income comes
from and who you owe money to.
Database programs can be horribly
complicated, so that you need to know
a special programming language just to
set them up. But there are some very
ELECTRONICS Australia, August 1990
simple options that you don't hear much
about, until now at least.
I use a little program called Cardbox,
which is simply a computer simulation
of a metal box filled with 3x5 index
cards. The cards can be anything you
want; I keep one file with cards containing details of interesting radio stations
I've come across. Another file has cards
with names, addresses, and companies
of contacts I have within the electronics
industry.
Cardbox can search through its collection of cards and isolate all of them that
match certain characteristics. For instance I can tell Cardbox to find all the
card records of electronic suppliers
which are based in Adelaide (two
characteristics), and it will select three
or four out of perhaps 100 in the box. I
can then flip through them, just as if
they were paper cards. What you see on
the screen is an image of a real card
with all the information neatly typed
into the proper places.
Like WordStar 3.3, Cardbox is probably a bit past it now and not actively
marketed, but as far as I'm concerned
it's still as useful as ever. It comes in
both CP/M and IBM versions. Perhaps
it's still available on the used market.
There are also Shareware versions; one
I think is called Cardfile.
Financial records are usually kept in a
program called a spreadsheet, which is
simply a 'rows and columns' ledger
book. A computer spreadsheet does all
the adding up for you after every new
entry or change. But addition is only
the start; computer spreadsheets can do
all the normal maths functions as well
Continued on page 149
4 inches high, 1000 MHz wide
puts the world in your pocket
The New IC-R1 handheld receiver
Icom , leading the way again in
communications technology and mini
aturisation with the world's smallest
wide band receiver.
It's so small you could carry it in the
palm of your hand or the pocket of
f
'.-7"71%.';
your shirt.
Yes,an FM/AM and FM /W wide -band
receiver that continuously covers
2 MHz - 905 MHz (Guaranteed
specifications) and yet is small
enough to carry anywhere.
'
-
,
Weighing in at a mere 280 g
(9.9 oz) this tiny package features
MULTI
-
including
Versatile Mobile
The New IC -R100 wideband
brings the world to your car
The IC -R100, with an ultra -wide
band width of 500 kHz to 1800 MHz,
was born of the technologically marvellous IC -R9000 (Icom's and the
world's
most
sophisticated
receiver). Operating from 13.8V DC
with a built-in 15dB pre -amp to
enhance weak signals (50 to 905
MHz ), the IC - R100 is invaluable
SCAN FUNCTIONS
programmed, memory,
as a mobile and for base station use.
Other features, such as an enormous
121 channel memory, built-in
clock/timer and, of course, multi mode scanning functions for VHF/
UHF /MW / HF make this a most
desirable receiver.
Compact, economical and easy to
operate as a scanning radio, it's no
wonder the IC -R100 is stimulating
great interest. By satisfying the
demands of shortwave and broadcast
listeners, scanner enthusiasts as well
selected mode and auto memory
write with a capacity for
100 MEMORY CHANNELS.
Electronic locking of tuning control
and keyboard prevents accidental
frequency change, 2 -way frequency
selection, a built-in clock and timer
functions - all running off an
internal Nicad battery. The IC -R1 is
equipped for high performance and is
a "must have" item for any one on
the move who is keeping up with the
world and technology.
Find out more about the IC -R1 and
the optional extras available - send in
or phone for a free brochure - BUT
HURRY - the R1 is selling fast!
..
llli.:
:811.5"33
,
39"
-
,''-
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as business and professional users,
Icom again leads the way. Contact us
by Freepost or phone for the name of
your stockist, colour brochures on
the IC -R1, R100 and the complete
range of Icom receivers - IC-R9000,
IC -R7000, and IC-R71A.
For further information call Icom free. on 008 338 915
Melbourne callers (OW 529 7582 Icom Australia Pty. Ltd., 7 Duke Street, Windsor 3181.
ICOM
Isom Australia's warranty is only applicable to products purchased from their authorised Australian Dealers.
AMATEUR
MARINE
LAND -MOBILE
AVIATION
CB
AMATEUR
MARINE
LAND -MOBILE
AVIATION
CB
AMATEUR
MARINE
LAND -MOBILE
Please rush to me your brochure on the O IC-R1, O IC -R100 and the name of my nearest Icom stockist.
SEND TO: Freepost 15, Icom Australia Pty Ltd, Windsor, 3181 (no stamp required).
Mr., Mrs., Ms.
Company
Title
Address
,
Suburb
City
AMATEUR
Post Code
MARINE
LAND -MOBILE III AVIATION
CB
AMATEUR
Phone No.
MARINE
LAND -MOBILE
NCAAa672'AEA
AVIATION
CB
AMATEUR
MARINE
LAND -MOBILE
READER INFO RIO. 9
LJ
Conducted by Jim
Rowe
Earth -leakage circuit breakers:
just how much safety DO they provide?
Let's take a break this month from esoteric things like unidirectional audio cables, and look
again at a subject whose perennial interest is exceeded only by its importance: electrical safety.
In particular, the exact nature of the protection afforded by that currently popular gadget, the
'ELCB' or earth -leakage circuit breaker.
It's not that I'm short of letters on
the subject of fancy audio cables; in fact
quite a few have arrived in the last few
weeks, and I'll try to deal with them
next month. No, the reason I'm changing the subject, for this month at least,
is that a couple of weeks ago another
letter arrived, drawing attention to an
aspect to electrical safety which we
if
haven't considered for some time
ever. This is the matter of earth leakage
circuit breakers, formerly called 'core
balance relays'.
ELCB's have been in the news quite a
lot of late, and I think at least one state
has recently enacted legislation to force
all new domestic electrical installations
to be fitted with one. There are small
portable ELCB's now on sale at almost
every hardware store, promoted heavily
on the basis of increased electrical safety.
But are ELCB's quite the universal
safety panacea that the marketing people would have us believe? That's the
and at least partly anquestion posed
by the writer of the letter
swered
concerned, Jeff Thomas of Engadine in
-
-
-
NSW. His letter is fairly self-explanatory, as you can see:
Let me first qualify my forthcoming
observations by stating that I am a professional electronics engineer, a qualified
electrician and licenced electrical contractor.
My concern and purpose for writing
this letter is the false sense of security
being offered to the public by the current
campaign surrounding earth leakage circuit breakers (ELCB's), and in particular the relationship between ELCB's and
double insulated appliances.
The impetus for the current wave of
publicity concerning ELCB's was the
electrocution of a five -year -old child in a
bath, due to a hair dryer falling into the
62
water while connected to the mains.
While this is obviously a tragedy in itself,
the other tragedy is that the child probably would not have been saved had that
circuit been 'protected' by an ELCB.
Consider the situation of the present
day bathroom. The bath would probably
be of steel or cast iron construction, with
a generous(?) coating of vitreous or synan insulator. This bath
thetic enamel
would then be supported on probably a
timber structure, sitting on a compressed
fibrous cement floor more insulation.
Some baths have provision for fitting
taps directly into the bath, while others
require the taps to be fitted externally in
the wall or surrounds. In any case if the
taps were fitted directly to the bath, the
plumber would probably have been careful not to chip the coating on the bath as
they were tightened down, so there
would' be no electrical contact between
the bath itself and the metal plumbing
system.
The drainage system to the bath would
almost certainly be glued plastic, and
thus the whole structure would be sitting
well and truly above electrical 'earth'.
So where's the out-of-balance electrical
leakage current going to go, if a non earthed (double insulated) appliance falls
into the well insulated body of water?
Nowhere!
An ELCB relies for its operation on
an out -of-balance current being present,
between the active and neutral conductors in the circuit. In general in this
country we work on a Main Earthed
Neutral (MEN) system, whereby the
neutral is tied to earth at each consumer's switchboard. Consequently the neutral is generally within a few volts from
earth potential anywhere in the system,
and the active is somewhere about 240V
AC above earth. Under normal circumstances it is obvious that equal and op-
ELECTRONICS Australia, August 1990
-
-
posite currents should be flowing at any
instant in both the active and neutral
i.e., they are
conductors in a circuit
'in balance'.
Should a fault occur in an earthed appliance, creating a leakage path to earth,
or should somebody in contact with
'ground' also make contact with the active conductor, some (maybe lots of)
current will be diverted to earth rather
than flowing back through the neutral
conductor. This will result in unequal
currents in the active and neutral conductors. It is this condition which causes
an ELCB to 'trip' and remove the voltage from the protected circuit.
Generally the difference in current detected at the trip point is as low as 10 to
30 milliamps, depending on the type of
device used, and the time taken to trip is
as the. literature claims 'within a third of
a heartbeat'. This is all very well, but
let's now get back to the bathroom situa-
-
tion.
A double insulated appliance has, by
law, no earth conductor to the appliance.
So if the water in the bath is not earthed,
and the appliance is not earthed, and
that appliance ends up in the water when
somebody is also in the water, what hap-
pens? Zap!
Because wet skin makes a relatively
good conductor, and because there
would be quite an intense electric field in
the water, a considerable amount of current would start flowing through the person, causing electrocution.
Now because no current is flowing
anywhere except up and down the active
and neutral conductors, no out -of-balhence the ELCB
ance situation exists
does not trip. About the only thing that
might save the hapless being in the bath,
in these circumstances, would be if they
made a grab for a tap, or some other
hunk of 'earth'. A child probably
-
some protection.
FORUM
Sometnmg tnat could nappen quite easily, in many bathrooms...
Why is a shock in this kind of situation so often fatal, even when there is
no direct path to earth? Simply because,
as Jeff Thompson points out, wet skin
makes a relatively good conductor. And
when you're sitting in water, there is
normally a large area of skin in direct
contact with the water. As the human
body is also composed largely of water,
its internal 'bulk resistance' is also relatively low.
So when you're sitting in a bath, your
low internal body resistance is very well
connected via the low resistance of a
large area of wet skin, to the equally
low resistance bathwater. Should any
current start to flow, there's no reason
why a very significant component of
that current can't flow through YOU.
And it takes only a few tens of milliamps to produce cardiac arrest.
It's obviously a far more dangerous
situation than that in say a typical workshop or lab, where you're likely to be
dry and clothed. With only a tiny area
of dry skin ever likely to be in contact
with an active circuit, should a fault develop, the risk of electrocution is much
lower.
Of course the risk of serious shock occurring in a workshop will be much
greater if you're working in bare feet on
a wet concrete floor. So don't infer
from what I've just written that you
can't get killed in a workshop or lab,
whatever you do. It's still a wise idea to
wear rubber -soled shoes whenever you're using electrical tools or equipment
especially when you're on damp ground,
or a damp concrete floor.
What I'm saying, and what Jeff
Thomas has pointed out, is that when
you, me or our loved ones are sitting in
a bath, we're all especially vulnerable to
shock. And that despite all of the hype
about ELCB's, these really don't offer
any protection at all unless you're connected to earth.
Frankly it seems to me that the main
lesson to draw from all this is to avoid
using electrical appliances in a bathroom when anyone is in the bath. It's
just too risky, in my.opinion.
But I suppose if you must use a hair
dryer in this highly risky situation, then
at the very least you should (a) have
your house wiring fitted with an ELCB;
and (b) follow Jeff Thomas's advice
about fitting a metal earthing chain to
ensure that the bathwater is reliably
connected to a known earth
so that
the ELCB can actually provide you with
-
-
64
Note that there's no point in just installing an ELCB, and not fitting the
earthing chain. Without the chain, the
ELCB simply can't provide any protecat least against the risk of bathtion
tub electrocution.
Perhaps Jeff Thomas is also right, that
we should try to have the electrical
safety authorities require double insu-
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level of protection offered by ELCB's,
Jeff Thomas has actually also hit upon
the solution to many of the 'tingle' and
hum problems produced by a lot of
double -insulated equipment. If double
insulated gear could legally be provided
with an internal earth connection, made
via the mains cord, it would become
easy to bleed away the capacitive currents that cause many of the problems
we've discussed in previous columns.
So his suggestion is well worth serious
consideration, I believe. What do you
think?
By the way, has anyone experienced
trouble with an ELCB tripping due to
the earth currents produced by RFI suppression capacitors, in earthed equipment? I suspect that this can probably
happen, especially if the capacitors are
larger in value than is specified in the
current regulations. Even though the
capacitive current to earth will be 90°
out of phase, it will probably still be
capable of tripping the ELCB
although this may depend upon the
particular design.
A final note, before we leave this subject for the present. Nothing in the
foregoing discussion is meant to suggest
that ELCB's are not worth using, in the
interests of safety. There are likely to
be many situations where a faulty appliance or accidental situation could cause
you or your loved ones to become con-
-
-
small plug-in ELCB marketed by
HPM: the 'Electresafe' DLD 5030.
A
lated appliances to be fitted with an internal earthed plate, to ensure that an
earth leakage current is bound to occur
if water enters the appliance.
Somehow I don't like our chances,
though. For this to work, double insulated appliances would have to be fitted
with three -wire cords and three-pin
plugs. Mention this to the same safety
authorities, and they're likely to have
apoplexy
currently they spend an
enormous amount of time and effort ensuring that double insulated gear is
never earthed, at least via a three -wire
cord and plug!
Seriously though, it's a very sensible
idea. Having an internal earthed metal
plate is not at all the same as having an
external earthed metal case. And the
main argument against the latter is that
faulty plug, extension cord or power
outlet wiring could allow the case to become alive. With the `earth' connected
only to an internal metal plate, this
couldn't happen.
It could even be, I suspect, that in
making this suggestion to improve the
ELECTRONICS Australia. August 1990
-
nected between the 240V and earth
and in such situations, an ELCB may
well save a life.
The thing you should bear in mind is
that an ELCB can only detect a problem if this produces a sudden change in
the current balance between the active
and neutral power lines. That's simply
the way the thing works.
So ELCB's are well worth having; but
they aren't a magic cure-all. As Jeff
Thomas has pointed out, an ELCB can
only protect you if you become part of
a circuit to earth
not if you end up
connected between active and neutral.
And the current to kill a human is far
lower than that needed to blow a fuse,
-
or trip
a
normal circuit breaker.
Shortform kits
Changing the subject again, some
time ago when we were discussing electronic project kits and component supply, it was suggested that a significant
number of project constructors resented
being `forced' by suppliers to buy complete kits. This was taking away half the
especially by the
fun, it was said
more experienced project builders.
The people concerned expressed the
view that being forced to buy a com-
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wouldn't be able to do this.
In case you were wondering, this is not
just a theory. A colleague of mine, after
some discussion about the problem,
tested the theory by throwing a bare
bayonet fitting attached to a lead plugged
into an ELCB 'protected' circuit, into a
bath in just such a situation as described
above. (But without the child
some
wives lose their sense of humour at
times...) There was plenty of hissing and
but no tripping of the
crackling
-
ELCB!
-
What is the solution?
In the short term, one solution I have
implemented in my own bathroom is to
go and buy a length of decorative metal
chain, attaching one end securely to a
tap and the other end to the bathplug.
The plug has to be in the bath for any
decent amount of water to be present,
and that water will therefore be earthed
through the metal chain back to the
plumbing system.
This if course will not work if you
have high pressure plastic water pipes in
your installation
then you would have
to find an alternative earth point.
In the long term it may be worth applying some pressure on 'the authorities'
-
to allow
-
indeed require
- sorne form
of earthed rnetal plate or ring WITHIN
an otherwise double insulated appliance,
just so that water ingress will cause
enough out -of-balance current to trip an
ELCB.
The purpose of this letter is not to
cause discussion. The problem is the
facts as stated above; the purpose is to
vent the problem to the community and
hopefully cause some action.
At the very least, let's hope we can
save a life by dispelling that false sense
of security surrounding
earth leakage cir-
cuit breakers.
Just when you thought
go into the water!
it
was safe to
Thanks for drawing our attention to
the problem, Jeff
I'm sure many
readers will applaud your public spirit.
You're probably also going to cause a
sudden sellout of decorative metal chain
in Australia's hardware stores, as soon
as this issue hits the streets!
Incidentally while Jeff refers in his letter to traditional metal baths with an insulating layer of vitreous or synthetic
enamel, many modern baths are made
entirely from epoxy fibreglass. But as
this is fully insulating, there will be even
-
of
a leakage circuit existing
unless you follow Jeff's advice and fit an earthing chain to the
water tap and bathplug.
It's ironic, isn't it, that one situation
where an ELCB isn't likely to offer any
real protection against electrocution is
that in a typical domestic bath
one of
the most likely of all places for shocks
less chance
to earth
--
-
to occur! Sobering, too.
As Jeff Thomas points out, the whole
basis for using an ELCB as a protective
device is the assumption that if a dangerous fault should develop, some of
the current normally passing between
active and neutral will be diverted directly to earth
so that the currents in
the two main conductors will no longer
be equal. But if there is no available
path to earth, this simply can't happen
and the ELCB cannot sense that a
fault has developed.
Yet as Jeff has also explained, it's still
all too easy for a person to be electrocuted, without having any direct connection to earth. All you need is to be
sitting in a bath of water, which is suddenly connected between active and
neutral by the immersion of a normal
unearthed, double insulated hair dryer.
-
-
ELECTRONICS Australia, August 1990
63
plete kit prevented them from using
parts they may have in their 'junk box',
left over from previous projects. It was
also producing a generation of 'lazy'
electronics people, they said, who
would only build a project or a piece of
gear if it was available as a fully packaged kit
complete down to the last
nut and bolt.
Why can't we buy just the bits we
need, they asked, or at least a 'short form' kit, with say only the PC board
and the other special or hard-to -get
components?
In short, there was a suggestion that
at least some of the electronics retailers
and kit suppliers might be cynically
manipulating the poor electronics constructors, by forcing them to buy complete kits.
Now I suspect that a small amount of
this does go on at times, although not
necessarily for the above reason.
Fact number 1: from time to time
many components
especially those
that have only recently been developed,
or are fairly specialised
can be hard
to get or in very limited supply. So
there are often situations where a supplier can only get hold of a relatively
small number of the specialised 'crucial'
parts for a particular project.
Fact number 2: from what I've
learned from the various electronics retailers, the majority of today's electronics constructors now seem to be essentially kit builders. Whether from 'laziness' or sheer lack of time to chase
parts, they simply prefer buying complete kits. This seems to apply to technicians and hobbyists alike; perhaps it's
a symptom of our frantic lifestyle.
Putting these two things together, the
retailer/kit supplier with limited stocks
of the crucial parts for a project is faced
with a choice: do they make the parts
available separately, for the sake of a
few independent constructors (who may
or may not choose to buy from them),
or do they use them to make up a batch
of complete kits
to please the rather
larger group of kit builders?
The choice is fairly clear, don't you
think? The complete kits are obviously
far more likely to sell, as well as providing more cash turnover. You'd do the
same if you were in the same position.
I'm sure
be honest!
Most of the time, though, the majority of retailers and suppliers are
surely happy to sell customers whatever
they want: separate parts, short -form
kits or complete kits. It's all business,
and the more choices you provide the
more likely you are to make sales.
In fact following some of the discus-
-
.
-
-
-
-
sion of these topics late last year, Dick
Smith Electronics decided to provide a
range of 'short form' kits for various
projects, in addition to their fairly extensive range of complete kits. These
were intended especially for the more
experienced constructor
those with a
bulging 'junk -box', as well as those who
wanted to adapt a published design for
other purposes. In many cases they included mainly the PC board and other
special parts.
The kits were for a variety of projects, from amateur radio gear to amplifiers and remote controllers. And as
you would expect, they were priced
considerably lower than full kits for the
same projects.
DSE also decided at the same time to
make available PC boards for many of
the projects, for those that were even
more 'independant'. Both these and the
short -form
kits were launched in
December 1989, and have been advertised fairly regularly since then.
Well, what do you think was the response? I gather it's been very disappointing. DSE still has many of the kits
and boards in stock, despite having reduced the prices even further, to try
and make them more attractive.
Where are all of those people who
complained about not being able to buy
short -form kits, and PC boards? That's
the question DSE's bemused kit people
are asking
one can hardly blame them.
It really does look as if the number of
people who want to 'do their own thing'
in constructing electronics projects is
now even tinier than we thought. So
tiny, in fact, that perhaps DSE and the
other kit suppliers would be quite justified in ignoring them altogether, and
concentrating on the majority.
To me this would be a pity, but perhaps it's inevitable.
What do you think? It's a subject that
should hopefully generate a bit of interest, if there's any future in electronics
construction as a rewarding activity. So
let us know your views, folks.
And if you are one of those 'independant' constructors who's keen on
seeing firms like DSE stocking PC
boards and short -form kits as well as
the complete caboodle, how about
checking out the DSE range, and putting a few dollars where your mouth is?
This is probably the only way to change
their minds about calling off the whole
exercise as a failure.
I gather the boards and short -form
kits have been withdrawn from stock in
all the stores, but are still available on
order from the mail order department.
See you again next month.
FLUKE 80 SERIES
MULTIMETERS
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wherever you
take it
Fluke 80 Series multimeters come in a rugged, water
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have an "input
warning if test leads are in the current jacks and a non -current
function is selected. They are
alert'
shielded
against
electromagnetic interference and are
protected against shock and
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Each Fluke 80 Series multi meter comes in a rugged protective holster, with a unique
"Flex-Stand"TM', which bends
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or hung almost anywhere.
To find out just how tough
a Fluke 80 Series multimeter
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FLUKE AND PHILIPS
- THE T & M ALLIANCE
PHILIPS
READER INFO NO. 10
ELECTRONICS Australia, August 1990
65
SPECTRUM
Communications News & Comment
WIDEBAND DISCONE
ANTENNA: 25-1300MHZ
ICOM MINIATURISES
COMMERCIAL
VHF HANDHELD
Recently, Icom's new miniature amateur band handhelds were released and
they've apparently been popular. But,
there was the inevitable question,
"Where's the commercial version?"
Now miniaturising VHF equipment
isn't as easy as miniaturising UHF. The
problem is, of course, that many components are just that much larger at
VHF. Commercial specifications are
also more demanding than those for
amateur gear. To be able to cram
everything in, do it in such a way that
100% reliability is assured and keep the
device right up to spec. is no mean feat.
But Icom engineers have done just that,
with the new IC -H10 VHF handheld.
While it is small in size, the unit is a
giant in performance: it has up to 5W
output (with suitable battery pack), a
full 26MHz bandwidth (with no adjustments required) and a variety of sophisticated user features. Yet it's just 58 x
85 x 29mm (w x h x d) and weighs in at
only 205g. Add your choice of battery
pack and it's still only 400g, and just
155mm high. So it will easily fit into
your shirt pocket , without straining the
stitches!
The IC -H10 covers a full 26MHz
(148-174MHz) with up to 10 transmit
and receive frequencies programmable.
Unlike many VHF transceivers, no crystals or diode matrix are required: the
IC-H10 has an EPROM to remember
all your details.
Further information is available from
your nearest Icom dealer. To find out
who that is, contact Icom Australia at 7
Duke Street, Windsor 3183 or phone
(03) 529 7582.
66
The latest breed of wideband HFVHF-UHF communications and scanner-monitoring receivers has renewed
interest in discone antennas. The discone configuration provides exceptionally wide bandwidth coupled with an
omnidirectional coverage in the horizontal plane, making it very suitable for
this kind of use.
The only problem is that discone antennas are not exactly thick on the
ground - let alone up the mast. Icom
markets one, the AH7000, with a rated
1300MHz. As well
bandwidth of 25
-
as being suitable for wideband reception
it can also double as an emergency an-
tenna for transmitting use, easily handling 100W input on the 50MHz,
900MHz and
430MHz,
144MHz,
1200MHz bands.
Apparently the demand for the
AH7000 has been so great that Icom
Australia's stock was cleaned out recently, and the firm had to increase its
orders from the factory. But the new
stocks have now arrived, and the antennas are again available.
The AH7000 comes with about 10m
of high grade co -ax, fitted with a type N
plug. Adaptors are readily available for
other connectors.
Further details are available from
Icom dealers, or from Icom Australia, 7
Duke Street, Windsor 3181 or phone
(03) 529 7582.
VESTIGIAL SIDEBAND
CATV MODULATOR
The Nexus VM-1 vestigial sideband
modulator is designed for small to large
CATV, broadband and inhouse monitoring systems.
Incorporating surface acoustic wave
(SAW) filters for accurate vestigial side .band response, the VM-1 blocks out
any unwanted spurious products less
than -6OdBc down. A high output level
of 120dBuV (60dBmV) together with
the various options makes the VM-1
suitable for various types of systems, as
large as 60 channels.
Options include group delay filtering,
ELECTRONICS Australia, August 1990
IF looping and stereo audio.The modulators are available in any PAL standard, NTSC or SECAM.
The VM-1 is a low profile (1U) 19"
rack mountable unit, making it ideal for
compact head end installation. Extremely easy to set up, it has video and
audio indicators and controls to control
overmodulation. Over 200 units have already been supplied to the Australian
market to date.
For further information contact MMT
Australia, 124 Boronia Road, Boronia
3155 or phone (03) 762 6455.
MOBILE PHONES GIVE
FLEXIBILITY
Mobile phones will let business executives of tomorrow choose when and
where they will work, a Sydney conference was told recently. Ms Candice
Gartner, National Marketing Manager
for Telecom Mobile Communications,
said productivity demands will mean
more than an eight-hour day for most.
"But at least in the nineties we will be
freer to decide when we'll work, when
we "play and when we will do both"
she said.
Ms Gartner said mobile phones had
shed their yuppie image and had become essential tools for small business,
trades people and their customers.
"Mobile communications are for
everybody and soon they'll be everyday
necessities, just like the fixed telephone,
colour television, video recorders, compact discs and personal computers," she
said.
"They're not fads and they're not elitist. They have a fundamental role in
Australian society and its changing
face."
Ms Gartner said that within 10 years,
more than 60% of all telephone calls in
Australia would involve mobile technology.
EARTH STATION FOR
ANTARCTIC TV
A new earth station commissioned for
Telecom New Zealand will provide a
novel entertainment facility for American support groups working ín the Ant -
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UPGRADED PHONE CALL SEQUE[I CER
Voca Communications has announced
the release of its updated telephone call
sequencer, the digitised CS -D40, which
now has a capacity of 40 incoming telephone lines as opposed to the old unit
which could only handle 12 lines.
All incoming calls are answered on a
`first -called, first answered' basis. When
answered by the machine, callers are
delivered a message and then placed on
hold with either a further message or
music -on -hold. If callers are kept
waiting longer than a pre-programmed
time, they are then delivered a second
message while the operator receives an
alarm to alert them to answer the call.
An attendant monitor advises the
operator of the oldest call in the group.
The CS -D40 has a 'barge -in' or 'start to -finish' option which can be selected
according to the length of the outgoing
arctic. The new station, with an 11 metre diameter antenna, was supplied
and installed by the Australian arm of
Scientific Atlanta Inc.
The earth station, sited near Christchurch in the South Island of New Zealand, will receive entertainment programmes beamed to US armed services
around the world from an American
transmitting station as part of the
Armed Forces Radio and TV Services
(AFRTS) network.
The programmes beamed to the Pacific area via the INTELSAT satellite,
consist of top sporting events, American
and world news and other entertainment programmes aimed specifically at
informing and entertaining US forces
stationed in foreign countries. The service is scrambled using the B -MAC
technology.
The newly -commissioned New Zealand link in the network will receive
message. On shorter messages, callers
can receive information from the beginning as soon as they are connected,
while on lengthier messages, callers can
`barge -in' to the message in progress
when they call.
Up to five lines can be placed on a
priority setting, allowing certain programmed numbers to be answered first,
such as STD-free 008 numbers.
An optional printer enables hard
copies of traffic information to be produced at regular programmable periods.
This not only allows businesses to roster
staff accordingly but is also ideal for direct response companies to measure results.
For further information, contact Voca
Communications, 11-29 Eastern Road,
South Melbourne 3205 or phone (03)
697 7000.
will then be
taped and shipped to the Antarctic for
replay on video cassette recorders for
support groups working in the desolate
reaches of the sub Continent.
these programmes. They
PHONES FOR FIJI
Alcatel STC claims to have consolidated its position as the nation's largest
exporter of telephones, with a significant sale of small business systems to
Fiji.
Valued at more than $380,000, the
for Commander BN systems with
a capacity of from three to 24 exchange
lines and between eight and 64 extensions. This is a follow-on from a similar
order received late last year, valued in
sale is
excess
of $250,000.
Alcatel STC also supplies Fiji with
one and two-line Commander E models
through Telecom Australia.
On the alert,
accurate
and safe
Fluke 80 Series multimeters come with a large number
of "alert" functions designed
to ensure safe, easy use.
The "Input Alert" prevents
accidental damage through
wrong lead connection. An
automatic power cut-off (after
30 minutes idle) extends battery life. This may be overridden in 36 hour record mode.
And the readouts couldn't
be easier. Fluke's patented
"Touch Hold"TM feature, when
activated, captures, locks and
displays each measurement,
yet leaves you both hands free
to position the probes. In the
relative mode, measurements
can be made relative to your
own reference point. And
there's a maximum/minimum
alert, plus automatic storage
of max/min readings.
And there's much more.
Why not be alert to all the special features of Fluke 80 Series
multimeters .. call your local
Fluke distributor today.
FLUKE AND PHILIPS
- THE T & M ALLIANCE
PHILIPS
READER INFO NO. 11
ELECTRONICS Australia, August 1990
67
NEW BOOKS
AND LITERATURE
ject of switch -mode systems. Then follow chapters dealing in turn with the
various building blocks
transformers,
inductors, power switching devices, IC
voltage regulators and controllers, and
magnetic amplifiers. There's also a section on the important topic of electro-
N OF
t
Sp
STAIV
-
pOpAÑER SUP1ntES
nde.m,
Power supplies
DESIGN OF SOLID STATE POWER
SUPPLIES, by Eugene R. Hnatek.
Third Edition, 1989, published by Van
Nostrand Reinhold. Hard covers, 235 x
160mm, 641 pages. ISBN 0-442-20768-9.
Recommended retail price $XX.00.
The first edition of this book was
published back in 1971, and needless to
say a great deal has happened in solid
state power supplies in the intervening
19 years. In fact it wouldn't be exaggerating to say there's been a virtual revolution, when you consider the developments that have taken place in switching
regulators, energy converter circuits,
regulator chips and power switching/control devices.
Mindful of this tremendous growth in
power supply and conversion technology, author Hnatek has totally re -organised and enlarged this edition to reflect
the current situation. Much greater emphasis is now given to switch -mode systems, while new material has been
added to cover recent developments in
such areas as high frequency operation,
resonant converters, the Cuk converter,
surface mount technology, MOSFET
switching devices, state-of-the-art converter and power supply ICs, distributed
power systems and rectifier selection
criteria.
The emphasis throughout is on sound,
but with
practical engineering design
sufficient coverage of theory to allow
this to be done. The author is Manager
of R&D at Viking Labs, a subsidiary of
Honeywell, and is a noted authority on
ICs with some 10 books, 40 papers and
250 articles to his credit.
After a general introduction to power
supplies, he covers the important sub-
-
68
magnetic compatibility. Then in the
final section of the book, he gives a detailed discussion of the design of some
10 different kinds of supply. These include a two -transformer DC/DC converter, a regulated flyback EHT supply,
a high efficiency Cuk converter, a frequency -controlled resonant DC/DC converter and a high peak -current supply
for a high speed matrix printer.
The text is concise, but quite readable, and is well served by illustrations.
In short, it seems a very comprehensive
text .and reference book on the design
of power supplies and converters.
The review copy came from the local
office of the publisher, at 480 La Trobe
Street, Melbourne. (J.R.)
The
-
3.
-
installation
Handbook
Cellular phones
THE CELLULAR TELEPHONE INSTALLATION HANDBOOK, by Michael Losee. Second edition, published by
Quantum Publishing, 1989. Hard covers,
242 x 196mm, 237 pages. ISBN
0-930633-05-9. Price including $75.
A comprehensive and down-to-earth
guide to cellular radiotelephones, written mainly for the electronics technician
who wants to set up in business as an
installer or repairer. The author has a
great deal of experience with the US
cellular phone system, being Product
Development Manager of Nokia-Mobira
one of the leading international cellu-
-
ELECTRONICS Australia, August 1990
lar equipment makers. He is also Technology Editor for the US magazine Cellular Business, and a well-known and
quoted industry spokesman.
Naturally enough the book deals
specifically with the American `AMPS'
(Advanced Mobile Phone Service) cellular system, but as Australia is adopting
the same system this should pose very
few, if any problems. In fact from an inspection, my impression is that the only
part of the book which will be of little
use or interest to Australian readers is a
list of US equipment suppliers, given in
one of the two data appendices at the
end.
Apart from this, the book seems to
cover the subject of cellular phones
rather well. It begins with a brief chapter on the history of cellular, followed
by an introduction to the basic theory
and operation of cellular systems. This
is followed in turn by chapters on test
equipment and tools, cellular telephones
themselves, antenna theory and selection, vehicle installations, marine installations, fixed rural installations and finally troubleshooting and repair techniques.
The author is obviously an experienced writer, and his text is concise and
highly readable. It's also well served by
clear illustrations. As a result it seems
an excellent introduction and reference
book on cellular 'phones, especially for
the technician who is more interested in
the practical side than in a lot of heavy
theory.
The review copy came from DNA
Communications, of 10 Welch Street,
Southport 4215, and the price quoted
includes packing and postage throughout Australia and New Zealand. Further information is available from DNA
by phone, on (075) 914 956. (J.R.)
Telecom myths
THE
TELECOMMUNICATIONS:
TIME FOR TRUTH, by Jack Keavney.
Published by Jack Keavney, 1990. Soft
covers, 210 x 148mm, 130 pages. ISBN 0
7316 9575 5. Recommended retail price
$12.95.
Back in the February issue, I commented in the editorial column on a
1Cntna
p1E
SNE
(
FOR1A
rt
first-hand report comparing the performance of Telecom Australia against
five major overseas telecommunications
systems, by Jack Keavney. It certainly
gave a lot of food for thought, with regard to the ongoing debate about deregulation, private competition and the
mooted amalgamation of Telecom,
OTC and Aussat to create a `Megacom'.
By the time you read this, some of
these matters may have been resolved
by the Federal Government. However
as I write this review in mid -June any
such decision is in the future and Mr
Keavney has just published this new
book, presenting a lot more facts and
figures comparing the telecom situation
here with that in other countries. Subtitled 'The Myths of Deregulation' it's
based on material gathered during a
second trip to the countries concerned,
earlier this year, in which he interviewed representatives from consumer
associations, telecom companies, unions
and regulatory bodies.
I might add that Mr Keavney has
published the book entirely at his own
(considerable) expense, and his trips
were also self -funded. The whole exercise has been to help ensure that whatever decisions are made by Australia in
this important area of national communications policy are made on the
Grid locator
"
THE ARRL WORLD GRID LOCATOR
ATLAS, by Folke Rosvall, S1I5AGM.
Published by the American Radio Relay
League, 1984. Soft covers, 278 x 215, 24
pages. Recommended retail price $8.00.
basis of objective evidence regarding
overseas experience, rather than blinkered ideology. We've certainly seen
quite a lot of the latter.
Jack Keavney is a former National
Director of the Freedom from Hunger
campaign, Foundation Chief Executive
of Enterprise Australia, Founding Director of the Australia For Quality Programme and a noted authority and consultant on Total Quality Management.
He has published an earlier book called
Private Enterprise, dealing with the legitimacy of profit and the benefits of
competition. So he's not only a very
public-spirited individual, but a champion of competition, efficiency and
quality of service.
Despite this background, and on the
basis of his trips and experience, Mr
Keavney is convinced that Australia
could make a very bad mistake by following blindly the kinds of telecom system deregulation that have occurred in
countries like the USA, the UK and
Canada. And in this book he presents
his evidence, in a clear and dynamic
fashion.
It makes very interesting and thought provoking reading. I only hope that if
decisions on Telecom Australia's future
have been made by the time you read
this, due account will have been taken
of the evidence he presents.
But even if this doesn't happen, it's a
book I can highly recommend.
Copies of the book should be available from major bookstores, but if you
experience any trouble it's also available
in NSW from St George Business Centre, 3rd Floor, 2 Cross Street, Hurstville
2220 or phone (02) 580 0440, and in
Victoria from TQC Equipment, PO Box
381 Heidelberg West 3081 or phone
(03) 459 7620. (J.R.)
This handy reference atlas for the DX
enthusiast was prepared by Swedish
amateur Folke Rosvall, SM5AGM. It
provides not only a set of maps giving
the codes for each location, but also
general information on the system and a
couple of programs in BASIC to allow
use of your personal computer to calculate (a) the locator code, knowing longitude and latitude; and (b) the direction
of, and distance to, any location from
any other location, with both entered by
code. There's also a fairly comprehensive list of countries and major cities,
with their codes.
The review copy came from Stewart
Electronic Components, of 44 Stafford
Street, Huntingdale 3166 (PO Box 281.
Oakleigh 3166), which can supply copies
by mail for the price quoted. (J.R.)
m
FLUKE 80 SERIES
MULTIMETERS
C ount on
them
to measure up
in more ways
Fluke
multimeters
are
made in the USA, to the highest standards, offering accuracy you can depend on ... and
they are guaranteed for 3
years by Philips, the name you
can trust.
Each
measurement is
clearly shown on the display,
so you know exactly what
you're measuring
without
having to check connections
or switch positions. Fluke
Models 83 and 85 have bar
graphs for analogue readings,
while the Model 87 has a high
resolution pointer.
The 10 -times zoom facility
lets you enhance resolution.
And your Fluke Multimeter
comes complete with protective holster, safety leads,
9V battery and operating
instructions.
To find out why no other
multimeter measures up to
the Fluke 80 Series... call your
local Fluke distributor today.
...
FLUKE AND PHILIPS
1,1411.11,5
- THE T& M ALLIANCE
PHILIPS
READER INFO NO. 12
ELECTRONICS Australia, August 1990
69
To Choose
The Best In
Sound
Quality, Be
Guided By
The Critics
"It
was clear and detailed with a crisp and attractively positive presentation.
Dynamic range was wide and the player produced vivid stereo with clearly localised
images."
JIMMY HUGHES. III FI ANSS ERS MAGAZINE (U.K.) ON TIIE PD9I REFERENCE SERIES C.D.
PLAYER.
am forced to note that the sheer goodness of the Pioneer revealed starkly the
inconsistent engineering standards at the BBC and other broadcast organisations."
"I
GOLD.
Al
HAT III FI MAGAZINE (U.K.) ON TIIE FYI REFERENCE SERIES AN/FM TUNER.
"The fidelity, lack of distortion and even the low frequency performance belied the
size of the speakers, their cost and their miniscule proportions. The quality of sound
was
right on par with my reference speakers and
I
more than impressed."
was
LOUIS CHALLIS. ETI (ELECTRONICS TODAY I\TERNATIONAL)ON 555T LOUDSPEAKERS.
used it to fill a restaurant with sound for
accolades on the sound quality all night."
"I
a
lively office party and accepted
PVT HAYES. ETI (ELECTRONICS TODAY INTERNATIONAL) MAGAZINE OF
SA
TIIE Z770.1IIDP SIZE III
STD'.
"Pioneer's Z990 should lie on the short list of anyone looking for
a
midi system."
CHRIS GREEN. AUSTRALIAN III FI MAGAZINE ON THE 2990 MIDI SIZE III FI SYSTEM.
"I
"purist" machine for sound
to the more general user."
ANSWERS MAGAZINE (U.K.) ON TIIE P09300 (PD71 IN AUSTRALIA)
see it appealing both to the audiophile wanting a good
quality reasons,
as
well
as
JIMM1 IIICIIES. III FI
REFERENCE SERIES C.D. PLAT ER.
is a high quality example of the genre. Build and finish are first rate,
and the lab performance was superb. Impressive in many ways, it can be
recommended with confidence."
"This player
MARTIN COLLOMS. a HAT III FI MAGAZINE(U.K.)ON TIIE PD6w0C.D. PLAYER.
a good idea having two trays, Pioneer has achieved this
enhancement very elegantly and with surprisingly little additional hardware."
"Given that it's
JIM ROS E. ELECTRONIC: AUSTRALIA MAGAZINE ON THE ARARDR'IN\ING PDZ:2T TWIN TRAY
C.D. PLAYER.
HIG11 COMMENDATION - DIGITAL
tt'DIO
CXTEGORY
C.E.S.A. (AUSTRALI.\).\SARDTOTHE PDZ72T TS INTRA1 C.D. PLAYER.
was virtually impossible to tell
normal broadcast picture and was mile" better than standard V I1S tape."
"Replay of PAL encoded discs gate superb results. It
it front
a
RICA NAM BURy.
PLAYER.
AA
Fl m
IIAT
AG
AZINE ON
TIIE CLDI iso/C1.D145o CONIRINATION C.D./C.D. VIDEO
"Many people will be surprised that it is a cassette based machine at all, so nearly is
it in danger of transcending the natural lirnitatioils, and so authoritative is its style of
delivery."
III FI CHOICE )LNG AZI NE (U.K.) ON THE C.T9I A CASSETTE DECK.
-
The CT656 is u distinguished entrant in the market for budget three head designs.
It can be confidently recommended."
III FI CHOICE AIAGAZI N E ( ('. K.)
"Pioneer have just launched
ON THE.
E CT6.56 C ASSETTE DECK.
a
player which sets
a
standard by which others will be
judged."
(4.014w
_....IJJ
o
-
. XI
S. MAYOR. WHICH
CO)IPAIT DISC/ MAGAZINE (U.K.)ON THE
PD91 REFERENCE SERIES
PL\1 ER.
Ws*
a package for this price and the only
good enough programming to exercise its virtues."
"Pioneer have done well to put together such
'I;
real prol.lenu
'e
to
fiat
CHRIS RR\ANT. III
TI N ER.
"This tuner
was
F1
I:IIIIICE
M
U:AZINE (U.K.) ON TIIE
E91
RF.FEIIENCE SERIES AM/F31 DIGIT.\I.
free of digital nasties and beneficed f
a
pleasantly quiet
background."
PAUL MII.I.F..R. II IIAT III FI
\i
\I:\ZI\I:II
.K.IIIN TIIE
"The Pioneer's impressive specification
F'2251.
\\IIF\I DIGITAL TI
NF:I(.
and build were confirmed by the listening
tests."
ü IIAT
III
FI M u(:
\ZINI:II'.K.)l)\ TIIE(:T:l:tA
CASSETTE DECK.
PIONEER®
BIT DON'T JUST TAM.; THEIR WORD. IIF::\It FOR l lll'RtiF:I.M: FOR 10111 VFtRF:tiT PI//rFElt DEALER PHONE
ue 1031580 991 Toll Free 108 338 179 Sydu/y (02) 132 1988 Td1I Frce 111)$ 231 5141
111e11
1
('...pA.. MA,wrt. AI349
READER INFO NO. 13
L
INFINITY'S TOP OF
THE RANGE
REFERENCE SYSTEM
YAMAHA'S YST-C11
I
MIDI SYSTEM
TECHNOLOGY
ELECTRONICS
$45,000+
WITH 'ACTIVE
INNOVATION
SERVO TECHNOLOGY'
AL f-1
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,
.
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.~1
AUGUST CONTENTS
ELECTRONICS
ETI-1630 'Blue Streak' RISC Computer
Ideas for Experimenters
-3
3
6
WORKSTATION
CD-ROM: The Light Fantastic
10
14
18
Basics of Microprocessors -4
Computer News & New Products
SPECIAL FEATURE
ON SPEAKER
TECHNOLOGY
SOUND INSIGHTS
Challis tests KEF's Inwall `UNI-Q' speaker
Speaker Technology: Ever onward & upward
Hitachi's new VT-LC5OEM laptop VCR
24
29
36
en ou ana
e gains
i
se
ase a
other measurement s stems
iii
FREQI'ET'CY RI;FP(1MF
aDIGIT
r
I
FREQUENCY
(He)
II 2000
rVV\I.1'/I:R
DIGIT
DECADE
SELECT
AMPLITUDE
I
IVs)
Hi
BIAS
IVpc1
LO
-
CN
SOOVpk
MAX
DIG
4Hlr -
E NTER
GAIN
GEN
PHASE
HARM
PRINT
I
p
RUN
Ill
CH
2
LO
. --GENERATOR
it
--
STOP
S
AC
Voltech
MENUS
i
DC
-
--
_
The new TF 2000 by Voltech is a totally self contained
instrument that simply and accurately measures gain,
phase and harmonics.
The TF 2000's high tech format contains its own
programmable sine-wave generator and has two input
channels for measurement. The generator excites the
system under test and automatically sweeps over any
frequency range from 0.01 Hz to 100 kHz, allowing it
to cover the frequency response measurement from the
largest mechanical system to the smallest high
frequency dc/dc converter.
Accurate gain and phase measurements are extracted
even when signals are buried in noise and distortion.
The TF 2000's accuracy and speed puts it light years
ahead of an oscilloscope trace.
Most new users find they can take accurate
measurement just 10 minutes after switching
the system on for the first time.
Put simply, the TF 2000 will:
Define stability of closed loop feedback systems.
Analyse motion control systems.
Determine band width and phase response
of amplifiers, etc.
READER INFO NO. 14
I1.
..t
Characterise linear and non-linear systems.
Analyse vibration and stress.
System analysis for modelling.
Harmonic analysis of non-linear waveforms
(to the 39th harmonic).
Serial and parallel ports for a printer or for
computer control.
It's digital measurement techniques, rather than
analogue, allow the TF 2000 to be more affordable than
its nearest competitor. Try less than half the cost.
The TF 2000 follows the successful release of the
Voltech PM 1000 AC Power Analyser to Australia.
And is distributed by Westinghouse Systems, the
industry leader in laboratory power measurement
systems.
Westinghouse
MAKE & SIGNAL
1
COMPANY
SrSTMMS
PO Box 267, Williamstown, Victoria, 3016.
Phone: (03) 397 1033 Fax: (03) 397 1861 Telex: AÁ37477
'
ETI
- continued:
Project 1630
i
THE 'BLUE S
RISC COM _TER
- 3
In this third and final article in the series, we get to 'fire up' the project. After that, it's all up to
your imagination, dedication and application. Article by Roger Harrison.
j
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___
The RISC card's DRAM is organised in four banks, eight chips per bank. This
gives the general circuit of each chip In each bank. The WE and RAS lines,
and the 10-bit RA bus, are common to all. The four CAS lines select the bank.
Before you attempt to fire up your Blue Streak, you need to
attend to the jumpers. See the accompanying panel labelled
'jumper Configurations'. You will also have to refer to the user
manual supplied with your card, because the jumper selection
of RAM and EPROM depends on whether you're using 1M or
4M of RAM and the EPROM size supplied with your card.
As the LEDs on the Blue Streak card are there for user
convenience, you should know a little about their functions
before firing up the card for the first time. The test/demo
software uses the row of four user programmable LEDs just to
the right of the 96 -pin expansion bus socket. They're there
primarily for convenience in the initial debugging of system
mode programs (they're not accessible from user mode
programs).
These LEDs are turned on by appropriate bits in the RISC's
bus control I/O port. This port also contains several other bits
that have a one time use during the bootstrap process, or
during the bus master phase of communications with the
PC/AT.
To the right and a little below these four LEDs is another,
marked BUS BUSY. This LED is provided as a visual indicator
of PC/AT bus activity. It is illuminated whenever the AT
processor acknowledges that the Blue Streak has control of
the bus; it is not directly programmable. It will light in
response to a request by the card for the AT bus when bit 0 of
the bus control port is set. The LED goes out when bit 0 is
cleared and the AT hardware has resumed control of the bus.
Getting going
Two floppy disks are supplied with the Blue Streak; one is
labelled BLUES/MONIT, the other is labelled CASM. The
configuration of your AT's drives doesn't matter at this stage;
ETI AUGUST '90
3
- 'Blue Streak' RISC Computer
Project 1630
ETI
PC -AT DATA BUS
SD(15:0)
RN20
DRPAC4
U49
74HCT573
U58
74HCT573
D(0)
7
8
-4.
12
8D
80
7D
70 13
70
70
6D
60
14
60
60
50
50
15
5D
50
40
40
16
30
30
17
6
4
80
80
2D
20
18
1D
10
16
I
(
RN15
DRPAC4
688
S
7
5
EN
OE
EN
12
OE
68R
RN19
DRPAC4
U48
74HCT573
80
80
1
70
7D
60
60
14
50
15
4D
40
16
30
30
17
2D
20
18
iD
10
19
4
l
13
5D
6
-1-7
_¡---
L.J
2
(
RN14
CO)
5
D(º)
D(6)
9
8D
80
3
D(10)
D(9)
8
7D
70 13
\/ 0(11)
7
60
60
6i
SD
50
5
4D
40
3D
30
20
0(11)
68R
DRPAC4
U57
74HCT573
7
\
0(10)
/ D(12)
D(13)
D(13)
5
SD(9)
10
14
SD
19
50(15)
CPU
DATA BUS
/
4
0(14)
0(14)
3
2D
0(15)
0(15)
2
iD
10
EN
,
OE
11
68R
IN -LATCH
SD(8)
/
D(12)
OE
EN
12
\
PC -RD -OE\
B-LATCH\
PC-WR-OE\
PC -AT
RAS
I/O
\
D
TO OTHER
DRAM BANKS
CAS\ (0,1,2,3)
RA(B:0)
.
1
\
\
\
\
\
\
\
\
\
TO OTHER
DRAMS IN
BANK
N
earlier articles in the series.
DRAM
RA(0)
5
AO
CAS\
RA(1)
8
Al
RAS\
RA(2)
7
A2
WE\
RA(3)
8
A3
RA(4)
10
A4
RA(5)
11
A6
RA(6)
12
A6
RA(7)
13
A7
DI
RA(8)
14
AB
DO
RA(9)
15
A9
16
3
02
b
1
17
CAS\ (0.1 ,2,3)
RAS\
WE\
RD(31:0)
RD(31:0)
5,6
TO RN 2, 3,
(LOWER DATA BUS)
AND RN 9, 10, 17 18
(HIGHER DATA BUS)
TO OTHER
DRAMS IN
BANK
ETI AUGUST
4
1
The schematics above and below
show sections of the circuit
which couldn't be squeezed into
-
,,
D(15:0)
LATCHES
'90
only one floppy drive
is necessary.
Load the Blue Streak card into a free slot. Leave the lid
open so you can see the on -board LEDs. Boot your computer
and go to the DOS prompt. Now, follow this procedure:
1.
2.
3.
4.
5.
6.
7.
8.
like reading the manual afterwards, but don't worry about it.
There you'll find mention of another demonstration program,
DEMO!. To try this out, just type DEMO! in place of DEMO2
in step 7 of the above procedure.
Note that there is also another README file in the root
directory of this disk, which is concerned with user
registration.
Put the BLUES/MONIT disk in drive A and type A:
Type CDIMONT
Type BSI MONT
Type CD1 BL UES
Type BLUES
Type CDI DEMO
Type LOAD DEMO2 7000
Type GO 7000
Epilogue
With your Blue Streak confirmed going, the rest is up to
you. The Blue Streak User's Guide gives comprehensive
instructions on commands and protocols, and other details.
The CASM User's Guide provides a very thorough and
comprehensive guide to using this programmer's 'tool set'.
Welcome to the world of RISC.
If all is well, the group of four LEDs will chase.
If you have any difficulties, type Ctrl C, go to the DEMO
directory and look at the README file. I know that sounds
Contributed by The Apogee Group
FROM DRAM
BANKS
JUMPER CONFIGURATIONS
R0(15:0)
RD(31:16)
- HIGHER
-
LOWER
Jumper pins
linked
ORDER
ORDER
J3
1
J4
1
JB1
JB2
JB4
JB7
JB9
-
-
1
1
1
1
1
2
3
4
7
RN
JB10 3
JB11
3
Usage
Jumper in for 256K or 512K EPROMs
2 Jumper in for 512K EPROMs
8 Jumper in for 4M RAM; out for 1M RAM
2 Jumper in for internal clock
2 Transparent/Latched. Jumper for latched operation
2 Jumper in for PC/AT extended port address range
2
8
slave (RISC) port number
6 All pins are left out
5 PC/AT port addresses Ox100 and 0x102
4 PC/AT DMA request line select (DRQ7)
4 PC/AT DMA acknowledge line select (DACK7)
7 PC
Note: JB3, 5, 6 and 8 are not used. Note that pin
on a jumper
block is marked with a chamfer, in the corner of the block outline on
the overlay (Fig.12).
1
8
47R
7
8
47R
Left and below are details of the
bit line and byte isolation
buffering.
47R
D(15:0)
D(31:16)
2,3
(LOWER
RN
ORDER)
--
LOWER ORDER
HIGHER ORDER
5,
(LOWER ORDER6)
10
(HIGHER ORDER)
RN 9,
RN 17, 18
(HIGHER ORDER)
BYTE ISOLATION
BUFFERS
BUFFERED DATA BUS
80(7:0)
RN13
DRPAC4
U26
74HC573
8
-4=
60(0)
9
RD
BO
12
80(1)
8
70
70
13
4H:=1
N
80(2)
7
BD
60
14
2
^
BD(3)
6
50
50
15
RNB
7
3
U33
74HC573
0(0)
D(1)
D(0)
9
80
80
12
130(0)
D(2)
0(1)
8
70
70
13
80(1)
D(3)
D(2)
7
80
60
14
80(2)
r
,
/
0(3)
6
50
50
15
80(3)
BD(4)
5
40
40
16
7
D(4)
0(4)
5
40
40
16
8D(4)
/
130 (5)
4
3D
30
17
5
0(5)
0(5)
4
3D
30
17
80(5)
,
B0(6)
3
20
20
18
3
0(6)
0(6)
3
2D
20
18
B0(6)
B0(7)
2
1D
10
0(7)
2
10
10
19
BD(7)
68R
DRPAC4
4
I
,
N.
11.
EN
J81
B -LATCH\
ISO
IN
0
0
2
BL\
0(7)
2
OE
EN
68R
OE\
OE
Y1
CPU DATA BUS
BL\
wBE\
ETI AUGUST '90
5
m
D(7:0)
I
/DIE
AInSes,
FOR
E
XIPE/R/I
M E N T E R S
INGENUITY
1690
1700
1710
1720
1730
1740
PROGRAM
1000
1010
1020
1030
1040
1050
1060
1070
1080
1090
1100
1110
1120
1130
1140
1150
1160
1170
1180
1190
1200
1210
1220
1230
1240
1250
1260
1270
1280
1290
1300
1310
1320
1330
1340
1350
1360
1370
1380
1390
1400
1410
1420
1430
1440
1450
1460
1470
1480
1490
1500
1510
1520
1530
1540
1550
1560
1570
1580
1590
1600
1610
1620
1630
1640
1650
1660
1670
1680
;++++++EXTRA COLOURS FOR THE C=128.++++++
;*************DEFINE LABELS*************
;THIS IS THE START ADDRESS
*=$1300
IVEC=$314 ;INTERUPT VECTOR
;PRESENT COLOR BANK
FLAG=$FB
CDAT=$1390;POINTER TO SPRITE,ETC. COLOURS
;THESE ARE THE HIGH BYTES TO
CCR1=$14
;THE CHARACTER COLOUR RAM BANKS
CCR2=$18
;THE LO BYTE IS ALWAYS $0. HENCE, COLOUR
;DATA IS AT $1400 (5120) AND $1800 (6144)
;THESE 2 GROUPS ARE SWAPED 60 TIMES/SEC.
;TO SET ALL THE SCREEN TO ONE
CLRP=$9E
;COLOUR, POKE CLRP/CLRP+1 WITH THE
;LO/HIGH BYTE OF THE COLOUR RAM.
;**********SETUP INTERUPT WEDGE**********
SEI
;SET NEW INTERUPT VECTOR.
LDA $<WDGE
;CHANGE 'WDGE' IN BOTH LINES
STA IVEC
LDA $>WDGE ;TO 'OTHR' FOR EXTRA SPRITE,
STA IVEC+1 ;MULTI. & BACKGROUND COLOURS
;THIS TELLS THE COMPUTER
LDA $0
;WHAT COLOUR RAM IS TO BE
STA FLAG
CLI
;DISPLAYED FIRST. ERASE IF YOU
;DON'T WANT CHARACTER COLOURS.
RTS
;*************TURN OFF WEDGE*************
SEI
;THIS ROUTINE INACTIVATES
;THE INTERUPT. TO CALL
LDA $$65
;THIS ROUTINE TYPE,
STA IVEC
;'SYS [VALUE OF *]+$11' OR
LDA $$FA
STA IVEC+1 ;IF YOU ERASED LDA $0,
;STA FLAG (ABOVE)->'SYS [VALUE
CLI
;OF *]+$OC'
RTS
:*****CHARCTER COLOUR INTERUPT WEDGE*****
WDGE LDA FLAG
LDX $CCR1
INY
BNE FILL
INC CLRP+1
DEX
BNE FILL
RTS
;BE FILLED WITH THE COLOUR.
;TO SET THE WHOLE SCREEN
;YOU'LL HAVE TO CALL THIS
;SUBROUTINE TWICE FOR THE
;TWO COLOUR RAMS:
READY.
10 FAST: COLORO, 1:COLOR4,1
20 SCNCLR:C2=4:C1=8:X=0:Y=0
30 P$="EXAMPLE OF POSSIBLE EXTRA COLOURS."
40 GOSUB220:P$="- STANDARD COLOURS
50 Y=3:X=10:C1=5:C2=10:GOSUB220
-'
60 P$="- ADDITIONAL COLOURS -":Y=7:X=9
70 GOSUB220:Y=5:P$="1 ":X=2
80 FORI=OT015:C1=I:C2=I:X=X+2:GOSUB210:NEXT
90 Y=9:X=4:FORI=1T037:READC1,C2:GOSUB210
100 X=X+2:IFX=36THENX=4:Y=Y+2:IFY=I3THENX=15
110 NEXT:SYS4864:CB=1:SLOW
120 GETKEYA$:CB=CB+1:IFCB=17THENCB=1
130 COLORO, CB:COLOR4,CB:GOT0120
140 DATA2,0,6,0,9,0,11,0,4,2,6,2
150 DATA8,2,9,2,11,2,5,3,13,3,14,3
160 DATA15,3,5,4,6,4,8,4,9,4,10,4
170 DATA10,4,11,4,12,4,6,5,10,5
180 DATA12,5,14,5,9,6,11,6,13,7
190 DATA9,8,10,8,11,8,12,8,14,8
200 DATA11,9,12,10,14,10,14,12,15,13
210 RV=1:GOSUB220:RV=0:RETURN
220 SYS65520 Y,X:PRINTP$
230 S=(Y*40)+X-1:FORV=1TOLEN(P$)-RV
240 POKES+V+5120,C1:POKES+V+6144,C2:NEXTV
250 RETURN
Extra colours for the
Commodore 128
EOR $1
;CHANGE COLOUR DATA RAM,
STA FLAG
BEQ SCNS
;WORK OUT WHERE IT IS
LDX $CCR2
SCNS STX STOR+2;AND STORE IT
;THIS IS THE HIGH BYTE OF
LDA $$D8
STA CRAM+2 ;THE COLOUR INFORMATION
;SENT TO THE SCREEN
LDY $0
LDX $4
Have you ever had the problem
with your Commodore 128 that It
doesn't display the correct colour
for a realistic presentation? For
example, for a skin colour the
computer only shows grey and
bright pink. Or maybe you
wanted to show the surface of
an object and there were not
enough tones of a certain colour.
This program more than triples
STOR LDA $1400,Y
CRAM STA $D800,Y
;TRANSFER DATA FROM COLOUR
INY
;RAM TO $D800+ TO BE PRINTED
BNE STOR
INC STOR+2 ;ON SCREEN
INC CRAM+2
DEX
BNE STOR
RETN JMP $FA65 ;GO TO STANDARD INTERUPT
;****SPRITE, BACKGROUND, MULTICOLOURS****
OTHR LDA SPCL+1
EOR $$E
;THIS DOES THE SAME AS
STA SPCL+1 ;'EOR'ING THE FLAG WITH 1.
LDX $14
;-THERE ARE 14 BYTES OF
SPCL LDA CDAT,X;DATA.
STA $D020,X ;TO FIND OUT WHAT THEY
;ARE LOOK UP YOUR MEMORY MAP
DEX
BNE SPCL
;IN THE 'PROGRAMERS
;R6PñRñNCE GUIDE' FROM $021.
JMP $WA65
;STORE YOUR 1ST COLOUR DATA AT 'CDAT+1'.
;STORE YOUR 2ND COLOUR DATA AT 'CDAT+15'.
;***FILL SCREEN WITH A SPECIFIC COLOUR***
LDY $0
;TO USE THIS ROUTINE A=COLOUR
;AND CLRP/CLRP+1=LO&HI BYTE
LDX $4
FILL STA (CLRP),Y ;OF THE COLOUR RAM TO
your colours, giving you an
additional 37 colours on top of
your standard 16. The program
alternates between two existing
colours to trick you Into seeing a
new one. (It should be possible to
have 112 extra colours, but found
that many flicker.) The colours
are alternated at sixty times per
second, i.e the speed at which
the raster updates the same row
again. If it were done any slower
or faster the effect would be lost.
When doing it faster than 60
times a second, the following
I
ETI AUGUST '90
6
could happen: the raster draws
green on the screen, and then
the program changes the colour
to brown and back to green for
the next raster. Therefore you will
not see the brown and, often,
mixing will not take place.
The program does the
character colours (which can
also be two hi -res colours), sprites,
multicolour registers and the
background. Not all the effects
operational
can
be
simultaneously as the Interrupt
would take more than a sixtieth
of a second and run Into the next
one, causing the computer to run
uncontrollably. The choice Is
between having Just the
character's colours (this Is the
longest Interrupt and there will be
a noticeable slowing In other
computer operations) or all of
the others listed above.
You will need an assembler to
type in the machine code. Take
note of the comments to help
you tailor the program to your
needs. For an example of what
When you run the demo, you
possible, type in the basic
program and run it with the
is
machine code in memory
will notice the writing is in a nonstandard colour. To write to the
starting at $1300. Press a key to
change the background colour.
screen with ease, let PS equal the
message, x/y equal the x and y
co-ordinates respectively, and
C1/C2 equal the first and second
colours to be mixed. Copy the
subroutine starting at line 210
and Jump to 210 If your message
has
reversed characters,
otherwise jump to 220.
Shane Harper,
Lalor, Vic.
CIRCUITS
Servo mechanism
joint moves to the desired
position. In order to reduce
overshoot, the drive to the motor
is reduced as the joint gets close
to the target value until the point
at which the target and actual
needed a voltage controlled
servo mechanism for use in a
robot arm, to be driven by a
I
computer
D -to -A. Commercial
servo mechanisms are expensive
($150) and the special pulses
voltage-to-PWM
up to A, which is more than
enough for small motors.
RV1 is the joint position sensor.
RV2 is used to set the midpoint of
the joint to correspond to half
volts on the Input. RV3 adjusts the
gain of the position sense. It is
adjusted so that the joint is, say,
fully flexed at perhaps 6 Von the
input and fully extended at, say,
4 V (with a 10 V supply). RV4
adjusts the gain of the error
circuitry, and effectively controls
how close the moving joint can
get to the set position before it
starts slowing down.
The output of ICla Is a voltage
ranging from near the positive rail
to near the negative rail,
depending on the error. This is fed
1
volts, or by a simple pot.
The motor and gearbox were
taken from a $3.98 toy car. The
shaft is connected to a nut which
is screwed up and down a bolt.
then connected to the
arm, acting In much the same
way as a muscle. The feedback
pot is connected to the joint and
detects the position of the joint
In space.
The circuit detects the
difference between the desired
position of the joint and the
actual position. If the difference
between the two is great, then
the motor is turned on full and the
This bolt is
converter.
Potentiometers RV5 and RV6 set
the Input values needed to
produce 0 V effective ranging to
V+
effective volts out,
respectively. ICld controls the
direction in which the joint must
move to reach the desired
position.
IC2 provides the necessary
logic needed to drive the output
transistors. Input 2 is optional, and
enables the driver transistors
when It Is high. If it is not needed,
it can be tied to the positive rail.
The two 1k resistors and the 10
uF capacitor divide the rail to
provide half rail references. The
motor should be run from a
separate rail three or four NiCads
provide adequate speed for 1.5-3
V motors.
Setting it up is straightforward.
The voltage readings here are for
a 10 V supply. First, disconnect
the power supply. Now set the
position sense pot (RV1) to the
position are equal, whereupon no
drive is applied to the motor. With
the values shown, the circuit can
drive motors with stall currents of
they need to drive them tend to
gobble up processor time. This
circuit is driven by a D -to -A
output port that can produce a
voltage of between O and 10
.10
Into IC1b which rectifies this error
to produce an absolute error. This
is fed Into IC1c, which is a
mid position (i.e the joint to the
mid position) and adjust RV2 so
5 V appears on the wiper of RV1.
Next, decide the Input voltage
range (e.g 3 V to 7 V). Disconnect
the wiper of RV1 to the circuit and
apply 3 V to the Vin input. Adjust
the gain (RV3) so 7 V appears on
the output of ICla (ICla Is an
inverter). Now reconnect the
wiper of RV1 and move the joint
so it is fully flexed, i.e the wiper of
RV1 has moved towards the
positive rail. Now adjust RV3 so
that 5 V appears on the output.
Next, measure the voltage at
'A' and adjust the Vin so that 3.6
volts appears here. Now
measure at point 'B' and adjust
RV5 so that B is just above O V
(set it at the O V position).
Finally, set Vin so that 3.6 V
appears at 'A'. Adjust RV6 so that
'B' is at or just below it. The gain
(RV4) may now be adjusted so
that the sensor responds quickly,
but doesn't overshoot or oscillate.
James Moxham,
cti
Urrbrae, S.A.
Contributed by The Apogee Group
V
12I0-P051TION
SET FULLY FT.00EO/EXTEN0E0
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ETI
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.cl
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AUGUST '90
-
LOW
CLOCCW1SE
7
.4.4
V
4,-
r-
'I
f
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-
M: THE
LIGHT FA TASTIC
After a slow beginning, CD-ROMs are gathering momentum as a data storage medium.
not the least being the ability to
Compared with magnetic disks, they offer many advantages
the same size as a standard
roughly
a
disc
on
information
store over 500 times the amount of
floppy.
-
by GEOFF BAINS
It is rare these days to find a computer user who relies on cassette tape
for data storage. Not only have cassettes all but vanished from the realms
of serious computing, but the days of
the floppy disk and Winchester hard
disk may well be numbered too. All of
these present day mass storage devices
are based on magnetic material, and
that is their downfall.
Enormous though the 20MB of storage available on a typical IBM PC/AT's
hard disk may seem, it is not really
large enough for the masses of information (especially high quality pictorial information) in common use on many
computers today.
Personal computers with up to 4M
bytes of RAM are becoming relatively
common. Equipping these with a floppy
disk drive which requires a handful of
disks and takes several minutes to fill all
of the computer's memory is more than
a little ludicrous. Larger and faster permanent storage is needed.
The future of mass storage is not with
most
magnetic media but with light
often seen in the form of an audio compact disc or 'CD'.
Even at the simplest level, optical
means of storing data are more efficient
than the usual magnetic methods. The
density of data from optical storage is
much greater. You only have to look at
a 35mm slide to see the kinds of densities possible
turn the idea around and
imagine the disk space required to store
a screen picture of that resolution.
The density of data in optical systems
is finally determined by the wavelength
of light itself (around one micron, or a
millionth of a metre, for the light used).
You can fit an awful lot of wavelengths
into a small area, and so fit in a lot of
data.
In comparison, the current densities
possible with magnetic storage are lim-
- AdúA
- Adait
IH
CCtOÍd.
orIouc.no.1
Adalt
IliAdult
Platt - at++
liter Alin
.
art
-
-
Many enclopedias are now available on CD-ROM, including Pergamon's
International Encyclopedia of Education
ited not by the size of grains of magnetic material on the tape or disk (typically a few thousandths of an inch) but
more by the size of the gap in the record/playback head. Even those minaturisation experts, the Japanese, cannot
wavelength -sized
magnetic
manage
heads.
Of course, the practical methods of
storing data optically do not come close
to these theoretical densities, but already they get a lot closer than magnetic methods will ever manage.
ETI
AUGUST '90
10
The potential benefits of optical data
storage have been known for some time
and it was in 1967 that Philips engineers
in Eindhoven in Holland came up with
the start of a practical solution.
Their idea was meant for the storage
of video and audio signals. A disc covered with marks detectable by reflecting
a laser off the surface would be used. A
disc was chosen as it was easier than a
tape to move at a constant speed and
could be stamped out in mass production.
The Philips invention turned into the
Table 1
Comparison of computer mass storage
Laserdisc video system. Although by
1972 Philips had demonstration machines on show and by 1978 (in the US)
and 1982 (in Europe) the commercial
machines were launched, the system
could not stand up to the convenience
of video cassette recorders and it has all
but faded into oblivion. However, the
Laserdisc was technically far superior to
the VCR and had great potential, both
for video and for storage of data.
The system uses tiny pits in the surface of a 300mm (12") disc, to modulate
the reflected beam of light from a laser
shining onto its surface as it revolves.
The pits are less than a micron (lum)
across, and arranged on a spiral track
(like an LP) which makes about 55,000
turns around the disc, each track just
1.5um away from the next.
All this gives a data density of about
35,000 bits per inch
miles better than
any magnetic media, and giving around
ten times the capacity of any small Winchester.
Although the Laserdisc failed commercially, it served to develop solutions
for the considerable mechanical problems of optical storage. The laser focusing lens reading the disc must be kept ati
exactly the right distance from the disc
surface (within 0.25um) and the beam
must follow the centre of the tracks to
an accuracy of only 0.1um.
However such mind-blowing accuracies are obtainable, and the money invested in Laserdisc technology has
found rich rewards for Philips and Sony
in the CD. It is the audio CD technology that forms the base of a whole
new standard of computer data storage
the CD-ROM.
CD-ROMs are in many ways similar
to both standard CDs and the old
Laserdisc. They use the same pitted surface technique for recording the data,
but are just 12cm in diameter. The disc
spins to keep the disc surface moving at
a constant speed (about 1.3m/s) past the
read head
so it must turn faster when
the centre is being read (about 500rpm)
than the outer tracks (around 200rpm).
The laser beam is focused on the surface and the reflections focused onto a
photodetector, which can register a
changes in light level as the pits spin
past the lens. Each change of light level
(the leading or trailing stepped edge of
a pit) represents a binary 1 and the flat
areas (`lands') in between represent 0's.
Useful data comes off the disc at an effective rate of 153.6kbps
a bit faster
than a floppy disk drive!
The data is encoded to reduce the efwhether from
fects of reading errors
-
-
Winchester
Media cost
Drive cost
Capacity
Media size
Access time
Data density
(US$)
(US$)
(MB)
200-1500
0.36-1.20
5-15
500-2500
550-680
13.34
30-300
15000
13.34
30-50
10000
400-1000
35000
scratches on the disc surface or glitches
in the system. At these data speeds it
only takes an error rate of one in a
100,000 to produce errors more often
than one a second.
The data must also be carefully identified to enable accurate random access
to be performed on the disc
so the
computer can read data from a section
of the disc directly, without reading all
before it. As a hangover from its audio
CD roots, CD-ROM is addressed in
units of 'playing time'.
The data emerges from the pickup as
a serial bitstream. These bits are dealt
with in lots of 588. First 27 bits of synchronisation data are stripped off. Of
the remaining, 297 bits are then removed in a condensation process called
'Eight to Fourteen Modulation' (EFM).
Since large long runs of zeros (flat
areas) would cause the read head to
wander, data is stored on the disc as 14 bit words, with only the 'best' binary
combinations used and a further three
bits are used to clearly separate each
byte. The 33 17-bit words are condensed with EFM to 33 conventional
8 -bit bytes.
One byte is a subcode byte containing
positional information and is sent to a
special decoder. Of the other 32, eight
-
CD-ROM
500-3000
5-50
n/a
(cm)
(ms)
(bits/in)
Floppy disk
1-5
12
are CIRC error correction codes bytes.
The remaining 24 bytes form the useful
data `frame'.
So far, CD-ROM is much like CD Audio. However, there is much more
stringent synchronisation and error detection used for CD-ROM.
The 24 -byte frames are gathered up in
'sectors' of 98
2352 -byte chunks. 12
bytes form more synchronisation data,
four bytes are the header information
(minutes, seconds and sector number),
2048 bytes are the final data and a massive 288 bytes form the complex error
detection and correction data.
Each 12cm CD-ROM disc can hold
276480 sectors, or 540MB (megabytes)
per disc.
The encoding against error detection
is very complex, and closely follows the
'Reed -Solomon' encoding system used
on audio CDs. As well as deriving
checksum bytes for each frame of data
(as do most digital cassette and floppy
disk systems), this also involves interleaving the 24 bytes of data in each
frame to split up any groups of bytes effected by errors (from, say, a scratch on
the disc).
This system can successfully correct
error bursts of up to 450 bytes long
(which would be a clearly visible scratch
-
-
~4
-
-
1
Hitachi's new CDR-1600S11650S CD-ROM drives are available in both Hitachi
bus and SCSI bus versions, and offer fast access time.
ETI AUGUST '90
11
CD-ROMs
or mark). Combined with the additional
error correction at block level (not
found on audio CDs) the CD-ROM system has a rate of uncorrectable errors
of just one in 10,000,000,000,00(1
about one in every two years of constant accessing!
This kind of reliability has meant the
CD-ROM is now taken seriously as a
data storage media. Mainframe computers have been using large optical discs
(not unlike the original Laserdiscs) for
some time, and now CD-ROMs are entering the world of personal computers.
At the moment CD-ROM drives are
available for IBM PC compatible machines and the Apple Macintosh. It will
not be long before other computers get
in on the act, and already drives for the
Acorn Archimedes and the Commodore
Amiga are under development.
Hitachi is the main CD-ROM drive
manufacturer at present, although
drives from other manufacturers are
also swiftly coming into use. A CDROM drive looks much like a floppy
disk drive, but it loads a CD-ROM disc
just like an audio CD player.
Microsoft has produced extensions to
the MS-DOS PC operating system and
the Macintosh operating system to accomodate the CD-ROM drives, and
these are accessed by software much
like a normal floppy disk drive.
Commercial CD-ROM data packages
are now widely available. Microsoft's
'Bookshelf was one of the first. This is
a single CD-ROM disc providing 10
reference works for writers using PCs.
On the disc are stored a comprehensive
dictionary, a thesaurus, a business information listing, a literary syle manual
and other useful tools for writers.
-
Any reference work is ripe for transfering to CD-ROM. Other products include a world atlas, the complete 18,500
page maintenance manual for a Boeing
757, all of the Sherlock Holmes stories,
innumerable programmer's libraries,
McGraw-Hill's 'Encyclopedia of Science
and Technology', book and record catalogues, and even a list of details on
every country in the world called 'The
CIA Factbook'!
The 'software' can be very expensive.
Some costs several thousands of dollars.
However, when you consider the fact
that each CD-ROM disc can store the
equivalent of 1000 PC disks, that the
CD-ROM drive and operating system
often come free with the package, and
you think of the time and resources to
check the contents of up to 100,000
Announced in 1988, Tandy's 'Thor -CD' system allows repeated recording and
erasure on CD compatible dye -based discs.
pages, it all seems more reasonable.
So reasonable, in fact that there are
now estimated to be about 100,000 CDROM users worldwide, and that number is increasing all the time.
What makes CD-ROM so exciting,
however, is not just the number of
words you can put on a small disc
but
what else you can put there too.
The discs are divided into tracks. Although just one track is all that's usually
needed, many can be incorporated,
each of a different format. So a disc
could contain speech, music and video,
all on one disc with complete computer
access and intervention in their replay.
Inevitably, games get a look in, and
-
the first is a graphics adventure game
called 'Defender of the Crown', from
the CD-ROM wing of the International
Pergamon Publishers, featuring CD Audio sound.
More serious applications include a
pronunciation disc to help foreign language students learn English.
However, although a great many
reference works are now appearing on
CD-ROM, therein lies the problem with
the whole system. CD-ROMs are in one
important sense just like semiconductor
they can only be read
chip ROMs
from, and not written to.
Once the information is stored on the
disc (by mechanically stamping them
out) it cannot be altered or erased.
What would be so much more useful
would be a 'CD -RAM'
a system with
the same speed and capacities, but
which could be written to by the computer just like a floppy disk or Winchester hard disk.
Writable optical storage discs have
been available for about four years.
Used only in research and large mainframes, these use larger 12" 1 -gigabyte
discs with a thin coating of metal (only
0.05um thick) on the surface. As well as
the usual low powered laser to read the
disc, a second more powerful laser is
provided which can melt tiny pits into
the metal film surface to form the pits
which store the data.
By modulating the powerful write
laser with the data from the computer,
these discs can be written to with whatever data needs to be stored.
A similar system uses organic dyes on
the disc surface. These require less
power from the write laser to alter their
reflectivity. ICI has produced 'Digital
Paper' which uses such dyes coated onto
a flexible base, which can be used in the
form of discs or even tapes. A 2400'
-
-
7
ICI's 'Digital Paper' also uses organic
dyes, and comes as both tapes and
discs.
ETI AUGUST '90
12
reel (an average 12" diameter spool)
holding 600GB of data
enough to
store three complete feature films in
digitised form.
Honeywell has started to produce an
optical tape recorder based on the digi-
-
tal tape. Japanese tape manufacturer
Taiyo Yuden has announced a record-
able audio CD based on similar principles. This is intended mainly for things
like prerecording radio station output,
but its application to CD-WORM is
only a matter of time.
With all these systems, however, once
the data pits have been formed in the
metal or dye coating on the disc surface, there is no going back. The surface cannot be re -leveled or re -coloured
and so the data is there for good. Such
systems are called WORM drives
Write Once, Read Many times.
The enormous capacity of a CD WORM means that room can usually be
found for altered data, and the operating system instructed to ignore the outdated data on the disc. These systems
find use in large databases for archive
storage.
Various archiving systems are produced based on Digital Paper and CD
equivalents. These are ideal backups for
large computer network Winchester systems, compared to the old streaming
tape system.
Truly erasable optical discs are still almost exclusively found in research labs.
Two types are attracting the most attention. The first type uses a phenomenon
known as the Kerr effect and a disc
coating of gadolinium-iron -cobalt. This
material has the effect of polarising light
reflected from it in the same direction
as it is magnetised.
The disc is first magnetised, and to
-
write data onto it a powerful laser is
used to heat the coating
which reverses the magnetic field at that spot.
The reversal of polarised light from the
read laser can then be used to detect
the heated spot. The whole disc may
then be erased of data by heating it
again in a magnetic field to produce an
evenly magnetised disc.
The second type of erasable disc uses
coatings of a tellurium -selenium alloy or
gallium antimonide. These materials
have the property of changing their
crystalline structure when heated, and
this affects their reflectivity.
Again, a write laser produces hot
spots of a temperature just above the
melting point of the alloy coating on the
disc surface, under the control of the
computer. When the spots cool (almost
immediately) they 'change their reflectivity and so allow the read laser to pick
them up from then on. The whole disc
can be erased by heating it to a temperature just below the melting point of
the coating, whereupon the alloy reverts
to its original structure.
Philips has produced reliable erasable
discs using the gallium antimonide coating, which can be recorded and erased
about 1000 times without degradation.
However, with both of these systems,
data cannot be overwritten. These are
`CD-EPROMs' rather than CD -RAM.
Much research is of course dedicated to
finding a suitable material to use for
CD -RAM.
A possible success has come from the
most unlikely of sources. The Tandy
Corporation (Radio Shack) announced
a recordable, erasable CD back in 1988.
Tandy reckons to deliver an audio CD
recorder for US$500 this year, and a
true CD -RAM system next year.
-
The Tandy `Thor -CD' system is a dye
based media and it is, Tandy claims, entirely compatible with existing CD technology and erasable and rerecordable
almost indefinitely.
A German division of the French
electronics giant Thomson has also announced a recordable, erasable CD.
This time it's double sided, like a cassette tape, but still largely compatible
with existing CDs. No expected date of
a product launch has been given.
Whatever the future of CD -RAM,
and it will certainly come one day, the
future for optical storage is already set..
With CD -WORM units containing several drives with a total capacity of several gigabytes, the necessity for overwriting ceases to be really important.
For small systems and even home
computers, CD-ROM drives are on the
increase and will surely be a commonplace sight before very long, even before alterability comes along.
The convenience and efficiency of
vast quantities of data compactly and
permanently stored and near -instantly
accessible is too great a temptation for
the personal computer industry to shy
from for much longer. Then, of course,
how about a 700 megabyte computer
game, with hifi sound and video pic-
tures...
-
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READER INFO No. 16
or
In Part 4 of a five -part series, Elmo Jansz discusses sub -routines and interrupts, and examines
logical operations.
THE
SICS OF
u ICROPROCESSORS
Most computers have a series of locations in Read/Write memory used for
servicing subroutines and interrupts. In
the Apple Ile, these are located in page
one.
A subroutine is a program which can
be used by a main program whenever
required. An interrupt is similar, except
that the MPU has to respond to a stimulus or signal from an external device and
go through a service routine. In either
case, the main program has to have a
means of returning to the correct point at
the completion of these secondary activities. The section of memory used for
these is called the stack.
The stack is often referred to as 'first in
last out' memory, because the first byte
placed on the stack is the last one taken
off; the stack is similar to a rack on
which plates are stacked. All stack
operations are controlled by an internal
register called a stack pointer, which is
eight bytes wide. We described the stack
pointer in an earlier issue, when we examined the programmer's model of the
6502. The stack pointer contains the low
order address of the next empty location
on the stack. Since the stack is located
in page one of memory, the high order
byte of any address on the stack is understood to be $01. Fig.1 shows a portion of the stack.
Assume that location $0108 on the
stack holds the byte $AA. The stack
pointer decrements each time information is placed on the stack, and points to
0100
0101
0102
0107
0108
m--, STACK
AA
POINTER
107)
-
the next available empty location
$0107 in this case.
Now suppose that the accumulator
contains the number $BB and that this
information is to be placed on
or,
using the correct jargon, pushed onto
the stack. The mnemonic for this operation is PHA with op -code $48 and uses
the implied addressing mode. When the
PHA instruction is executed, the number
$BB is placed in the location above that
containing $AA and the stack pointer is
decremented.
The new status of the stack is shown
in Fig.2. Notice that the stack pointer
now points to the next available location, namely $0106.
The reverse procedure takes place
when information is pulled from the
stack by the PLA instruction. When the
MPU encounters the PLA instruction, it
first increments the stack pointer. In this
case the stack pointer now holds $07
and the byte $BB is transferred into the
accumulator. A similar procedure takes
place if $AA is to be transferred into the
accumulator. After this, the stack pointer
is incremented to $09 which is the next
-
-
empty location.
Let us now examine the manner in
which the stack is used by the MPU in
servicing a subroutine. The stack is used
to store the address to which the main
program must return after the subroutine
is serviced. The MPU uses two instructions to do this, the JSR (jump to subroutine) and the RTS (return from subroutine). The following program segment includes a JSR.
1. 034D 8D
) Load the accumulator
2. 034E 03
) with the contents of
) $0403
3. 034F 04
4. 0350 20
5. 0351 00
6. 0352 03
)
)
Jump to subroutine
located at $0300
)
7. 0353 Main program continues...
Lines 4, 5, and 6 tell the program to
01FF
jump to the subroutine located at $0300.
After servicing the subroutine the proFig.1: After a byte 'AA' is pushed onto
the
stack,
the
pointer
is
decremented.
gram must return to line 7, address location $0353 and continue with its main
activities. Assume that before the JSR inETI AUGUST '90
14
0100
0106
0107
0108
0109
.5
(STACK POINTER'
BB
AA
(06)
01FF
Fig.2: After a second byte is pushed
onto the stack, the pointer is again
decremented.
struction the stack pointer contained $B9
- see Fig.3.
You can set the stack pointer to point
to any location you wish, but this is not
necessary as it will automatically use an
empty location in page one.
The address of the third byte of the
subroutine which is $0352 is pushed
onto the stack before the MPU deals
with the subroutine
see Fig.3. ADH =
$03 is first pushed onto the stack and
the stack pointer decremented. This is
followed by ADL = $52 and the stack
pointer is decremented. The MPU now
deals with the subroutine.
The last instruction in a subroutine is
the RTS (return from subroutine), which
reverses the above procedure. The stack
pointer is now first incremented and the
ADL of the return address is read from
the stack. The stack pointer is incremented and the ADH of the return address is read from the stack. This information ($0352) is placed in the program
counter, which is then incremented to
give $0353. The main program therefore,
continues from this location.
The JSR and RTS instructions require
the MPU to perform a fair amount of
work. These instructions consequently
take up a lot of time. From the op -code
chart they each require six clock cycles.
-
When computer time
is at a
premium,
only
Observe that the AND goes to
when both A and B are 1. The OR goes
to 1 when at least one of A or B is 1.
when A and
The Exclusive -OR goes to
B are complements of each other. The
last column shows the complement. This
is the inverse of what we start with. The
numbers A and B do not necessarily
need to be one bit numbers. The 6502 is
an eight bit MPU and deals with eight
bit wide binary numbers. In this case,
each of the above operations will be
performed on a single bit basis.
Let us look at some examples:
= 0011 1010
Let A = $3A
Let B = $F1
= 1111 0001
(1111 0001)
A.B
= (0011 1010)
subroutines should be avoided. When
the computer is first switched on, the
stack pointer has a random number in it.
This does not lead to any problems since
the stack has 'wrap around' facilities.
That is, if the stack pointer if $00 and it
is decremented, then its new value will
become $FF.
The stack pointer can be set to any
value by first loading the X -register with
the desired value and using a TXS
(Transfer X -register to stack pointer). This
is an unnecessary procedure.
When the MPU receives an interrupt
from an external device, the system has
a routine built into it on how the interrupt should be serviced. The procedure
is very similar to that in which a subroutine is handled.
1
0
1
1
0
0
0
1
1
1
0
symbolised by
A®B
0
0
1
1
A
0
1
1
1
1
A
1
0
0
03
52
PROGRAM COUNTER
0100
--(STACK POINTER
1
53 ADL
03 ADH
01FF
a
to
Before
jumping
subroutine, the return address is
pushed onto the stack.
Fig.3:
0000
= $30
$F1 gives us $30.
Observe that any bit that was ANDed
with a 0 was changed to 0 and any bit
that was ANDed with 1 remained unchanged. Changing a bit to 0 while leaving others unchanged is called masking.
The bits changed into 0's are said to be
masked. The AND operation is shown
on the op -code chart as AAM->A. This
means that the number in the accumulator is ANDed with the contents of
memory location M and the result
placed in the accumulator, replacing the
original number that was there. You
should now write out a small program
segment to try out the AND operation
and run it on your computer. For example, load the accumulator with $3A.
AND it with $F1 and store your result in
some memory location. This is the example we had earlier, and should have
the same answer, namely $30. A solution should look like this:
.
0
0011
ANDing $3A with
Not included in the above list is the
complement or inversion which the
MPU can also carry out The complement of A is written as A Let us now
examine the table below which further
illustrates these points.
A B
A.B A+B A®B Complement
0
1111
1010
0001
0011
-
-
ORing $3A with
LDA
#$3A
AND
#$F1
STA
BRK
$03D0
Assemble and run the program and
examine location $03D0 for your answer. The OR -function can be examined
in a similar manner.
Using the same values for A and B,
i.e.:
=
(0011 1010)
A = $3A
=
(1111 0001)
B
= $F1
Rewriting the numbers one under the
other:
0011
1111
1010
0001
ETI AUGUST '90
15
$F1 gives $FB.
Observe that any bit that was ORed
with a
gave a 1. The OR instruction
can be used to change bits from 0 to
by ORing the appropriate bits with 1.
This is useful for setting bits in a word.
The OR operation is shown on the op code chart as A V M->A. This means
that the number in the accumulator is
ORed with the number in a memory
location M and the result placed in the
accumulator.
You should now write a small program
to try out the OR operation. A program
to OR the above two numbers should be
1
1
as
follows:
Rewriting the numbers one under the
other:
The 6502 has facilities for carrying out
both arithmetic and the following logical
operations: AND, ORA, EOR, BIT, ASL,
LSR, ROL and ROR.
The first three are defined as follows
(assuming A and B are single bit binary
numbers):
symbolised by A.B
AND= AND operation
symbolised by
OR = OR operation
A+B
OR operation
FOR = Exclusive
B
F
.
Logical operations
1011
1111
1
LDA
ORA
#$3A
STA
BRK
$03D0
#$F1
The exclusive OR of the two numbers
A and
B is
determined
as
follows:
= 0011 1010
= 1111 0001
A®B = (1111 0001) ® (1111 0001)
Writing them one under the other:
$3A
$F1
0011
1111
1010
0001
= $CB i.e.,
A®B = $CB
Bits in a number can be complemented by executing an exclusive OR
with a number whose corresponding bits
1100
1011
l's. The bits are left unchanged by
carrying out the operation with a number whose corresponding bits are 0's.
Check this against the example given
above. The exclusive OR operation is
shown on the op -code chart as
AVM-A. This means that the number in
the accumulator is being exclusive ORed
with the number in a memory location
M and the result placed in the accumuare
lator.
You should now write a small program segment to check out the Exclusive
-OR operation and run it on your computer.
The BIT instruction is very similar to
the AND instruction except that the result is not stored.
The BIT instruction is shown as MAM
in the op -code chart. Note, there is no
arrow to indicate that the result goes into
the accumulator as we had with the
AND operation. The logical values of
bits 6 and 7 of the memory location accessed by the BIT instruction are placed
in bits 6 and 7 of the P -register, i.e:
M6-V and M7->N
Microprocessors
The BIT instruction can therefore be
used to modify the V and N flags in the
corresponding to the information in bits 6 and 7 of a location in
memory.
Let us now examine the shift and rotate instructions. We shall first define
each one of these operations.
ASL
Arithmetic shift left: each bit of
the operand is shifted left.
Bit 0 goes into bit 1, bit 1 into bit 2
and so on. Bit 7 goes into the carry flag
and a 0 is shifted into bit 0. A series of
ASL operations is equivalent to multiplying by two, four, eight, 16, etc.
As an example $03 = 0000 0011.
After
one
ASL
this
becomes
0000 0110 which is 0610. After a second
ASL,
the
number
becomes
0000 1100 which is 1210, or $0C and is
the result of multiplying the original
number by four.
P -register
-
-0
.
FIg.4: The operation of the 6502's
'ASL' instruction.
.
1111
L
The ASL is indicated in the 6502 opcode chart, with the addressing modes
available to it. Notice the last column indicates that only the N, Z and C flags in
the P-register are modified by the
ASL instruction.
LSR
Logical shift right: this is similar to the ASL concept that the bits are
shift right.
A logic 0 is shifted into bit 7 and bit 0
is shifted into the carry flag.
A succession of LSR instructions is
equivalent to dividing by two, four,
eight, 16, etc.
-
0The
`LSR'
instruction
equivalent to dividing by two.
Fig.5:
Odd numbers will lose a bit when
divided by two. The loss of bits by a
series of right shifts destroys only the
fractional part of the quotient and for
some problems this may be acceptable.
If this is not the case, software must be
available to save the fractional part. Locate the LSR instruction on the op -code
chart and observe that the flags involved
in the P-register are still the N, Z and C
flags.
e
tl
,
'/
'
-
ROL
Rotate left. In this operation,
each bit of the operand is shifted one bit
to the left just like in the ASL. However,
in this case the carry flag is shifted into
bit 0.
A series of nine ROL operations will
leave the operand and the carry flag in
their original states. Identify the ROL instruction on the op -code chart and note
that only the N, Z and C flags are modified by this instruction.
ROR
Rotate right. This is just like
the ROL instruction except that the bits
of the operand are shifted right. Bit 0
goes into the carry flag, and the carry
flag is moved into bit 7.
-
r
Fig.7: And finally, the operation of
the 'ROR' instruction.
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Mail Orders: P;O.Box 626, Caringbah, NSW. 2229. Australia
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Computer News
1_TLi
.
and New Products
Micromouse
competition in NZ
The search for New Zealand's smartAt this year's National
Electronics Conference (Nelcon) in
Auckland, rodents of the electromechanical variety will be put through
their paces in a bid to discover which
one is best at negotiating a specially
est mouse is on.
gang/set
programmer
PC -driven
built maze.
For further information contact Ian
Cardno at Auckland University's Centre
for Continuing Education or phone (09)
The Logical Devices' `Husky' is a
gang/set programmer driven directly
from an IBM PC via a plug-in card. It
uses intelligent and quick pulse algorithms to program as many as four one megabit EPROMs in less than three
minutes. Each of the four 32 -pin ZIF
sockets supports gang programming of
EE/EPROMS simultaneously with the
same data, or sequentially with different
data.
Devices supported include most popular CMOS, NMOS and HMOS EE/
EPROMS and CMOS EPLDs. Single
chip micros are also supported using an
optional 40 -pin expansion socket. Similarly, PLCC and PGA devices can be
supported by additional socket adaptors.
The advanced software forms friendly
user interface, which can be used under
cursor or mouse control. There are no
high voltages on the plug-in section of
the programmer, eliminating the danger
of damaging the PC in case of a programmer malfunction.
further
information
For
contact
Emona Instruments, 86 Parramatta
Road, Camperdown 2050 or phone (02)
519 3933.
737 999.
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V1'320 modes, as well as Tektronix
4010/4014 graphics. Its 64 foreground
and background colours, and unique
dual-sessioning and dual -host ,features,
are made possible by its advanced Application Specific Integrated Circuit
(ASIC) chip and a 16 -bit MC 68000 microprocessor.
The terminal's flexiblity is further extended by the number of display formats available, up to 52 rows or 161
columns. It can be connected to two
host systems, or two ports on the same
system, and has advanced windowing
capability, allowing the screen to be
split, horizontally or vertically, to display two distinct sessions simultaneously.
For further information, contact Wyse
Technology, 112-118 Talavera Road,
North Ryde 2113 or phone (02)
888 7455.
Colour printer for
the Macintosh
r
Hewlett-Packard has introduced the
Paintwriter XL colour -graphics
printer. This is HP's third colour printer
that lets Macintosh users express themselves in colour at a relatively economical price (US$5600).
It prints a page of colour graphics in
minutes
and
has
1.5
a
dual
Appletalk/RS-422A interface.
The inkjet printer has automatic sheet
feeding of transparency film and paper
for high -volume printing and networking needs, and handles letter (A/A4)
and tabloid (A3/B) media sizes. It has a
simple front panel and platinum case
typical of Macintosh printers.
Macintosh users now can choose from
the HP Paintwriter XL, or the HP
HP
High-performance
colour terminal
Wyse Technology has announced a
new high-performance colour terminal.
The WY -370 is the latest in Wyse's
`Terminals of the 90s' series and is
claimed to set a new performance standard in the general purpose terminal
market.
The WY -370 offers a range of industry -standard ASCII and ANSI emulations, including WY -350 and DEC
The MAESTRO 2400XR
i2400-xR
Here's a fully-featured, Hayes compatible 1200
& 2400 bps full duplex modem for just
$299 (incl. tax).
the LATEST in DSP chip 'IL.
This modem uses
Set Technology and microprocessor control,
bringing you the future Today.
inémbu(uliomnnr
MI
I -.--
.p
The MAESTRO 2400 ZXR
$399 (incl. tax).
4 Speed Version
Don't Wait! RING NOW (043) 68 2277 or 68 2278
Maestro Distributors
Super price on a super V.221V.22 bis Modem!
READER INFO NO. 18
ETI AUGUST '90
18
Calool St. South Kincumber, NSW 2256
Paintjet and HP Paintjet XL printers
with the HP colour Printkit for Macintosh computers. With these products,
they can create colour desktop presentations, desktop -published documents and
spreadsheets.
All of these printers support 32 -bit co-
lour Quickdraw. They offer background
printing
spooling capability in the
software driver allows customers to use
their computers while the printer is op-
-
erating.
For further information contact Hewlett Packard on (008) 033 821.
board memory access. In addition, appropriate wait states can be added to
I/O channels either in dynamic or non dynamic mode.
The ROM subsystem consists of .two
64K by 8 -bit ROM/EPROM sockets and
housed in two
16K by 8 -bit
is
ROM/EPROM modules organised as
16K by 16-bit.
For further information contact Electronic Solutions, 5 Waltham Street, Artarmon 2067 or phone (02) 906 6666.
Autotrax now also generates automatic solid polygon fills for either the
top or bottom layer of a PCB. These
solid fills `wrap -around' existing tracks
and pads, and allows the designer to
leave solid copper conveniently positioned wherever additional shielding is
desired.
Autotrax's V1.5's autorouter has been
re -written to improve both completion
rates and route quality for most designs,
including single -sided and SMD technology applications. Support is now provided for VGA graphics displays up to
resolution.
The Print/Plot utility has been re -written to improve output quality and efficiency, with particular emphasis on improved Gerber (R) plot generation.
New drivers have been added for Epson
LQ (TM) and compatible 24 -pin print1024 x 768
-.o
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Autotrax upgraded
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AT motherboard
for old PCs
Electronic Solutions has just released
high performance 12MHz/0 wait state
PLAT motherboard that fits into pretty
a
well every old PC and AT case on the
market. It is useful where there is a
need to upgrade an older machine, or
where a compact (and low cost) AT
motherboard is needed, with good expansion potential.
The board is based on the high performance Texas Instruments PC/AT 3 chip set. The motherboard is half size,
yet has five 16 -bit slots and one 8-hit
slot. The size is 8.6" x 8.6". The onboard memory is 1MB or very fast
(80ns) RAM. Speeds available are 8 or
12MHz with 0 or
wait state, so the
board can be used with slower memory
chips if required. Switching can be done
from keyboard or via jumpers on the
motherboard.
The motherboard achieves higher performance than other designs by the use
of an innovative `advanced bus'. This
caters for users with a mixture of slower
peripheral cards and newer 'fast slot'
cards that can work at higher bus
speeds. The motherboard caters for all
these cards by using dynamic I/O speed
control. This switches the system clock
to 8MHz for I/O instructions or off 1
Protel Technology has released an upgraded version of its popular Autotrax
printed circuit board design package for
IBM-PC (R) and compatible computers.
Designated Version 1.5, the new version features a switchable metric/imperial grid system that supports a mix of
metric and traditional imperial components. A true metric grid is now provided, not just a coordinate display.
Both metric and imperial dimensions
are generated and displayed for all design elements, such as tracks, pads and
holes. The designer can toggle between
metric and imperial measurement at any
time during board layout.
Designers can now automatically include curved transitions when manually
routing connections. Curved tracks are
of special benefit to analog and high frequency designs. This feature is also
supported in the autorouter, where an
Arc Replacer option automatically
smooths 90° corners into arcs on routed
PCBs.
The upgrade to V1.5 is available free
of charge to all registered users.
For further information contact Protel
Technology, GPO Box 204, Hobart
7010 or phone (002) 73 0100.
Autodesk Expo'90
Autodesk Expo '90 is to be held from
August 8-10 at the World Congress
Centre, Melbourne. The three day conference and exhibition will highlight the
latest developments in the CAD, CAE,
three-dimensional modelling, interactive
design, graphics software and related industries from Australia and overseas.
For further information contact the
Expo Secretariat on (03) 698 4210 or
call toll free (008) 033 148.
PC SOFTWARE
POWER SURGE
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ui ment's
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The best of the world's public domain software
and shareware for IBM PC and compatible
computers, catalogued into Australia's most
comprehensive and up-to-date collection.
Membership $45 pa includes:
Monthly updates &
member's program reviews.
$5 per disk (5.25' format)
$6 mail order.
200 page catalogue.
Available in the following
Current Ratings.
1 Amp. 3 Amp. 6 Amp. 10 Amp.
WESTINGHOUSE
BRAKE & SIGNAL COMPANY
Westi..L....
AUSTRALIA LIMITED
ers.
PHONE (03) 3971033
Open Mon-Thurs 9-5, FrI 9-9, Sal 9-1.
r
srsreeu
FAX (03)397 1861
COM
READER INFO NO. 19
ETI AUGUST '90
19
Also 500
Mac
Disk
Library
6
PUBLIC DOMAIN
22 QUEEN STREET,
MITCHAM VIC. 3132
TEL: (03) 874 3666.
FAX: (03) 873 4086
SME/EN6.90
READER INFO NO. 20
COMPUTER NEWS & NEW PRODUCTS
Industrial label printer
\:Q.191,1.
Facit's high speed T9700 label/bar code printer is specially
designed for heavy-duty industrial use, providing high -quality
bar codes, graphics, variable text and OCR on up to 256mm
wide labels or tags and combines complete label design capabilities with modern industrial labelling requirements.
The printer can accept either thermal paper (direct thermal
printing) or ordinary label paper (print ribbon thermal transfer printing), to create in seconds, labels that would take almost a minute on normal scanning matrix printers. Print
speed is rated at 50mm/sec.
For computer communication, the printer is equipped with
RS -232-C serial, and Centronics parallel interfaces, and has
an advanced set of instructions for label creation which
.covers a library of bar code types such as EAN, UPC, Code
39, and variable text. This means labels and tags can be
easily created in batch mode or on -demand mode.
For further information, contact your local Elmeasco Instruments office or phone (02) 736 2888.
,t
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(G
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8 . . IEEE
EEE &
easy
-use
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Our
for
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PC/A11386
With
interfaces packed
PS/25 are features tpower-on
loads
commd+
device
µlt-pacdstyle
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capability
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utomd['cÁ¡nd¿c
ONSItQ 300K
BASIC
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ELECTRONIC CAD
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IEEE oards/computer
software
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compatible
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EEE
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NEC,210
channel
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languages ,
interrupt
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and
popular
DMA
with
PROTEL
--
NEW VERSION
EASYTRAX, IOW COST PCB
AUTOTRAX, PCB WITH SMD
NEW VERSION
SCHEMATIC, WITH PCB INTERFACE
TRAXSTAR
TRAXVIEW
EVALUATION PACKAGES
°mP¡led
. Compatible
QuickBASIC, BASIC,
(n0 extras10buy)tcludinBASICA
GWBASIC
BASIC,
OrCAD
BASIC, Microsoft C.
Pasc, G Aztec
:
Turbo
OrCAD/SDT III, SCHEMATIC/CAPTURE CAD
OrCAD/VST, DIGITAL LOGIC SIMULATOR
OrCAD/PCB, PBC WITH'SMD
OrCAD/MOD, PLD SIMULATION MODELING
OrCAD/PLD, PROGRAMMABLE LOGIC DESIGN
Microsoft
Fortran,
Microsoft
C,
Windows,
Lattice
many more.
TBASITurb° C,
Pascal,
8950
81800
$2600
$950
8950
PSPICE
AYSTDadSTes
S-3/SymPre,
ANALOG CIRCUIT SIMULATION
DELUXE DOS VERSION, WITH OPTIONS
DELUXE VERSION FOR OS/2
DELUXE VERSION FOR OS/2 INCLUDING
NEW DIGITAL LOGIC SIMULATION
DIGITAL FILE OPTION FOR DOS VERSION
ALSO AVAILABLE FOR MAC, NEC, DEC, SUN
& APOLLO
Au'OCAD,
ntec
$1200
$3000
84600
86000
$450
CALL
SPECTRUM
SCIENTIFIC DEVICES AUSTRALIA PTY. LTD.
MICRO -CAP III, ELECTRONIC CIRCUIT ANALYSIS 81990
MICRO -LOGIC II, ELECTRONIC DRAFTING
$1250
Melbourne (03) 579 3622
& SIMULATION
Fax (03) 579 0971
Sydney:
(02) 344 5200
Fax (02) 349 2602
Adelaide (08) 281 3788
Fax (08) 281 4194
P.O.
READER INFO NO. 21
$350
$1490
$890
CALL
CALL
CALL
ETI
Technical Imports Australia
Box 92 Crows Nest 2065
Tel: (02) 954 0248 Fax: (02) 925 0311
AUGUST '90
20
READER INFO NO. 22
instrumentation,
transducer
output
analysis, transfer function measurements, and data acquisition systems.
For further information contact Warburton Franki, PO Box 14, Lidcombe
2141 or phone (02) 648 5455.
mt
High speed EPROM
a.rrr4.
@ .r
.
Q
programmers
Advin
t
`Sailor'
range
-
nificant advance for this type of instrument. Each unit is directly controlled by
an IBM-PC/XT/AT/PS2 or compatible
computers.
The units are fast and intelligent.
They may be operated in the 'set' or
`ganged' mode. It does not use the slow
RS-232 type of communication, but has
been designed to interface with the PC
through the standard parallel printer
port. A `virtual memory' feature makes
use of computer RAM and disk space.
RAM expansion modules are never
needed, even
for high capacity
PROM's.
No serial downloading is required between the PC and the programmer. Devices may be programmed all the same
or set to burn different data simulta-
Rapid Systems has introduced the
R1250 transient waveform analyser.
This uses the power and flexibility of an
AT personal computer to provide four
independent, 1MHz, 12 -bit analog to
digital converter channels.
A large 256K waveform data buffer
provides up to 64K data buffers for
each channel. Colour VGA display provides resolution for the mouse/menu
driven instrument interface software.
Four independent channels each with
programmable gain allow multi -channel
recording of applications like biomedical
I
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.
Postcode:
ETI AUGUST '90
21
-6.,
14111.
New PLC and
free. software
Texas Instruments has announced a
brand new TI405 PLC and a free software offer for its recently launched 305
Controller, which is a direct replacement for the GE Fanuc series One.
Anyone purchasing the TI305 PLC,
For publication! Yes/NO
Address:
I,I
wW.
Reader Information
Card
Name*
Í
!
'
On the reverse of this page you will find the Reader
Information Card. This is a service EA with ETI provides
free to readers who want more information about
products advertised or otherwise mentioned in the
magazine. At the bottom of the article or advert you find a
RI number. Just circle that number on the card and send
the card to us. We will pass on your address to our
contacts, either the advertiser or our source for the story,
who will then inundate you with literature on the product
of your choice. Another feature: to the right, there is a
blank space. Why not use it to drop us a line, and let us
know what you think of the magazine. We are particularly
interested in ideas from readers on how we can improve
things.
.
:. ..
Note to the Editor:
withg=t
il
of
EPROM programmers represents a sig-
Transient
waveform analyser
A
Systems
neously into each device. The Sailor
Systems support all programming algorithms standard, fast and quick pulse.
With its software it is portable to any
machine that has the standard parallel
interface. There is no interface card to
remove or install.
For further information contact Kenelec, 48 Henderson Road, Clayton 3168
or phone (03) 560 1011.
time, store them and simultaneously display the image on an external monitor.
If real colour is required, three VDIGI
boards will provide an RGB input/output.
This imaging sub-system will enhance
a PC, allowing it to be used for new applications such as robotics vision, image
archival, automation quality inspection,
graphics resolution and many others.
The board comes with menu driven
software which performs all grabbing
and manipulation functions. The onboard videó buffer fits neatly into the
64K segment barrier of the IBM PC architecture. This feature results in a
more versatile, cost effective and faster
capture and most importantly, faster,
cleaner image processing code.
The ability to capture an image and
transfer it quickly to the PC system
RAM, provides a greater increase in
analysis speed for high -end users,
removing the I -O bottleneck.
The cost effectiveness of the VDIGI
opens it up to a wide range of potential
users
from the professional designing
an OEM system to the serious enthusi-
COMPUTER NEWS & -NEW PRODUCTS
which retails for approximately $379,
will also receive free software that allows them to convert easily and conveniently from Logic Master to Tisoft.
The TI305 PLC has an input/output
capacity of 24 to 168 points including
control system and S/3 Supervisory Control and Data Acquisition (SCADA)
digital, analog and intelligent input/output. It maintains one of the smallest
footprints of any PLC on the marketplace.
The 405's scan speed was found to be
fastest in a comparison with over 180
other PLCs. Besides multiple colour
LEDs are provided on CPU and I/O
modules as well as 96 descriptive error
messages to locate problems.
The 405 uses either Machine Stage or
RLL diagrams. Machine Stage programming offers faster programming and increases functionality yet requires only a
few simple commands to operate. It is
also claimed to make debugging easier.
Both the 305 and 405 product families
are part of TI's full line of automation
controls, ranging from the basic and
complex machine, to cell/area control
with TISTAR and production line/plant
control through the TI D/3 distributed
887 1122.
¡wiles
E;
r na
t:u
system.
For further information contact Texas
Instruments Australia, 6-10 Talavera
Raod, North Ryde 2113 or phone (02)
.=
423.1..£1.1.1.1,11!.
J -!1
-
compatible
frame grabber
PC
-
The AES VDIGI frame grabber adds
real-time image acquisition, processing
and display to the range of IBM PC,
XT, AT, 386 and compatibles.
It will capture video signals from real
111 11111 I
1
1.1_1 11_11_1\
h1
Electronic Solutions, 30 Charles Street,
Bentley 6102 or phone (09) 451 2665.
I- 1llll 1 Illll_
11 1-I IIsI I
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READER
ast.
For further information contact Adept
If YFi71 Pf?14TfOf Y
%1
SERVICE
To find
out more about the products and services in this Issue,
note the Reader Service Number from the advertisement or
article, and circle the corresponding number in this coupon.
Enclose it In an envelope and send to:
FREE POST No. 4
No stamp required
E.
.°
posted in Australia.
O
Please
the box
that best fits you.
Manager
F. Teacher/Lecturer
G. Student
H. Interested Consumer
I.
it,
Other (please state)
O
O
O
Name
Company
Address
L
31
7
10
32
33
34
35
11
36
61
12
13
14
15
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17
37
38
39
40
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43
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45
46
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48
49
50
62
63
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65
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68
69
70
3
8
9
21
P/C
Telephone
6
52
53
54
55
56
57
58
59
60
2
4
The Federal Publishing Company
P.O. Box 227. Waterloo. N.S.W. 2017
A. Engineer/Designer
B. Technical Officer
C. Technician
D. Programmer/Analyst
5
26
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)
AUG '90
ETI AUGUST
22
'90
J
HAVE YOU CONSIDERED A
IN ELECTRONICS
'
'
ER
:NG?
Australia's leading electronics magazine is looking for
a project designer/writer to join its editorial staff.
This position involves the design and development of
hobby electronics projects (covering every facet of
electronics), and then putting the project into words for
publication in the magazine.
You'll need a sound knowledge of electronics theory
and practice, lots of enthusiasm and a good sense of
humour. You'll also need to have a good knowledge of
the English language, both written and spoken. You
could be a student, a technician, a fully qualified engineer, a teacher, or just a very keen enthusiast.
If you think you're the person we're looking for, or you would like to like to know a little
more about the position, please phone us on 693 6620, or if you prefer, fax a copy of your
resume to Jim Rowe, Electronics Australia, on 02 693 6613, Federal Publishing Company,
180 Bourke Road, Alexandria 2015.
0 COMPU
S PLAY
IN YOUR LI
ANY PA
NEWS
YOUR COMPUTER brings you all that's
interesting, innovative and inventive in
news of
the microcomputing world
products, plans and politics to keep you
up-to-date with what's going on in this
fast-moving industry.
-
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or if you want to find
they do
don't
out more about them
miss each month's issue of
PROGRAMS:
_FUTURE
The latest machines and software from
computer manufacturers are reviewed
each month in YOUR COMPUTER.
Keep informed about what's available,
and use our surveys to help you assess
which products are right for you.
YOUR COMPUTER'S tutorials include
regular series on such popular subjects
as programming languages and dBase,
probably the biggest -selling database
program of them all. Written by well -
.
4
IC(Mill
REVIEWS:
TUTORIALS
,_
ir
YOUR COMPUTER regularly publishes
all kinds of programs written by both professional programmers and readers,
and ranging from games to business
uses, utilities to additions and alterations
to well-known programs.
All YOUR COMPUTER'S articles are
written in everyday English, not computer jargon, so even if you're a beginner
there's something for you in every issue.
And our regular columns on all the popular brands of microcomputers are
packed with enough information to get
any newcomer straight into the exciting
world of computing.
for all computer
enthusiasts and users, YOUR
COMPUTER will make you part of
the computing world.
A magazine
Pus
,
4
known industry experts like Stewart Fist
and Matt Whelan, they're an invaluable
aid to learning how to make computers
work for you.
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the centre of a wide range (low
frequency) speaker diaphragm. This
particular development is one of the first
fruits of their research into speaker -room
interactions, and the concépt has been
further refined during an extensive R&D
program called 'Project Archimedes'
in which KEF combined resources with
those of Bang & Olufsen, for a wide
ranging and comprehensive three year
study
of psycho -acoustics
at
the
Technical University at Lyngby in
Denmark.
Many of you may well have found
memories of an earlier generation of
Tannoy dual concentric coaxial speakers
which were in vogue around 30-40
years ago. The underlying concept of
those speakers was to provide a true
wide range 'point source' speaker
system, to optimise stereo imaging for
both professional and consumer sound
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amplification systems.
Whilst the Tannoy (and other) coaxial
KEF's position as one of the world's
leaders in speaker technology has been
built on a solid foundation of basic
research into acoustics and the optimum
perception of reproduced sound. Some
of you may already be aware of the
work of their technical director, Laurie
who
Fincham
developed
the
computerised 'Decay Response Analysis
Procedure'.
This is now
generally
acknowledged as the most outstanding
technical breakthrough in the 70's, as it
provided us with the first objective test
procedures through which we could
direct
between
obtain
correlation
objective testing and how a speaker
sounds. Over the last 15 years KEF's
R&D programmes have continuously
expanded their horizons, particularly in
the area of subjective perception of
amplified sound.
Some of their more recent technical
advances (some people would describe
them as breakthroughs) have included
the KEF 'coupled cavity bass system', for
improved bass response from small
speaker enclosures, as well as their
development of the 'Conjugate Load
Matching Networks', which in effect
doubles the power output of most
amplifiers used with their reference
speaker systems.
Most recently, and significantly in
terms of this review, they have
developed
the
'UNI-Q'
Driver
Technology, which places a tweeter at
CHECKING OUT
KEF'S INWALL
'UNI-Q'
speakers resorted to short flairs on the
extended voice coil, or even adopted
miniature tweeters mounted on a bracket
in front of the voice coil dome, the KEF
UNI-Q driver system has followed the
concept which Technics initiated in their
SBR 100
series
speakers,
and
has
positioned the tweeter right in the
middle of the mid -range driver's voice
coil magnet assembly.
The UNI-Q driver utilises an unusual
miniature
domed tweeter with
a
miniscule neodymium iron/boron alloy
magnet
assembly,
whose
magnetic
properties are claimed to exceed almost
all
conventional magnetic materials
previously developed for commercial
applications.
By placing the UNI-Q tweeter right at
the centre of the associated speaker's
magnetic circuit, and by correctly
shaping the diaphragm of the adjacent
driver, KEF have been able to provide
what they claim to be the most
outstanding dual coaxial speaker on the
market.
A significant
part of the 19mm
diameter tweeter's superior performance
has been achieved by winding an
unusually lightweight voice coil on an
extremely
thin
and
equally
light
aluminium former. To compensate for
the reduced thermal inertia (and thus for
R
S
So keen was Louis Challis to try out the CR160 custom `in -wall' version of KEF Electronics' new
`UNI-Q' coaxial/coplanar loudspeaker driver, that he cut a hole and mounted it in the door of his
ánechoic room. Later he also tried out a pair in the saloon of `Pixie', a luxury 11.5m yacht
is
there no end to his dedication?
-
ETI AUGUST '90
24
_
its
reduced
thermal
dissipation
capabilities)
they
have
added
a
'Ferro -fluid' which not only enhances
the heat dissipation characteristics of the
tweeter
by
almost
an
order of
magnitude, but more significantly (as
they
found),
provides
substantial
transient damping to minimise ringing at
the cessation of transient peaks.
"Very interesting," you say
"but
don't want to spend thousands of dollars
on a Reference Speaker System!"
Well, KEF also realised that, and to
many reviewers and quite a few of their
competitors' surprise, they decided to
enter the lucrative 'Architectural Audio'
-
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C
market with a brand new speaker.
They decided that they would be
capable of capturing a significant share
of this burgeoning market, which has
already attracted some mighty strong and
equally innovative competitors. Foremost
amongst these firms in the USA are
Sonance and Boston Acoustics, and
there are a number of smaller firms
most of whom appear to be 'one trick
ponies'.
There are many people who want a
high quality loudspeaker which they can
build into walls, or which are designed
to 'customise' into their new and
expensive furniture. There are others
who want speakers to recess into
ceilings, or loft spaces, into walls of
caravans or even place in the bulkheads
of boats. These speakers should be
of
capable of providing a level
performance which is hopefully on a par
with a conventional hifi system; instead
of sounding like a cheap loudspeaker in
a lift car, and certainly better than those
in a cheap transistor radio.
investigations confirmed that
built-in loudspeaker, there are a
series of psycho -acoustic and practical
construction related factors which call
for the smallest possible size of cut-outs
you need to make in a wall, bulkhead or
ceiling in which a 'built-in speaker
system' is to be installed. Unlike some of
their competition, from the outset they
set out to simplify the fabricators' tasks
as much as possible and obviously
without
sacrificing
technical
performance.
Realising that these speakers would be
installed in a wide range of potentially
inclement (or in some cases even hostile)
environments, they opted for a water
resistant polypropylene cone and for an
all metal voice coil for the low frequency driver.
To achieve maximum rigidity and to
KEF's
with
-
a
compensate for anticipated deficiencies
in the future mountings (over which they
would have no control), they chose a robust cast -aluminium speaker basket support frame. This ensures a stable long
term axial alignment between the voice
coil and the magnet assembly. To simplify the system installation even further,
integral cross -over network
is
the
mounted directly on the rear of the
woofer magnet. This has been combined
.,
with
a tweeter protection network which
reduces the tweeter drive voltage when
excessive high frequency voltage is applied.
As
found, the cross -over and protection circuit provide a practical separation
element which minimises possible contact of loose elements within the space
in which the speaker is to be mounted.
Further protection for the speaker diaphragm is provided by a neatly fitted
cloth cover over the back of each speaker, which inhibits the entry of insects,
metal particles or other debris which
I
I
Above: the construction of the UNI-Q
driver, with the tweeter voicecoil very
close to coplanar with the bass
voicecoil (as well as coaxial). At
right: installing a driver in Pixie's
saloon.
I
ETI AUGUST '90
25
u
iiló
ullll
Challis on KEF's 'UNI-Q' driver...
tends to shorten the life of most speakers.
Overall dimensions of each speaker
are 220mm (square of diameter), and
89mm deep. Each speaker is terminated
in a pair
of 300mm long colour coded
leads, each of which is terminated by
polarised quick release automotive type
-
making electrical
covered connectors
connections to the speaker both simple
and straightforward. KEF also provide a
matching pair of connectors so that your
cables may be quickly and conveniently
extended and terminated with minimum
complication.
Realising that the purchaser will have
distinct and individual taste, they supply
a pair of speakers in one box, and you
may then choose either a pair of circular
or a pair of rectangular bezels with
matching perforated white grilles. These
push -on grilles ensure adequate protection and offer reasonable durability
under most (but not all) practical working conditions.
Having learnt from their competitors,
the grilles sensibly incorporate an acoustically transparent, but visually opaque
polyester cloth screen which hides the
presence of the supplementary mounting
elements. The literature provided with
the grilles claims that they may be
sprayed to suit specific decors, and that
.the polyester cloth may also be sprayed
or dyed to match; but did not put it to
the test. To top it off, as well as providing cutting templates, 'rough -in' frames
of glass reinforced plastic polymer are
also available for new constructions
which is very sensible. And as subsequently discovered, they have also developed a matching optional built-in
sub -woofer system which extends the
low frequency response down to well
below 40Hz.
I
-
I
Checking it out
When it came to testing the CR160
speaker, we first decided to mount it in a
panel in the doorway of our anechoic
room, to duplicate a wall or celing
mounting system.
This turned out to be most complex
and proved generally unsatifactory from
a standardisation point, not only because
of the way the panel was installed in the
anechoic room's only doorway, but also
because the guy who cut the main panel
had opted for a panel with dimensions
of one metre square. The same member
of staff placed a supplementary panel
immediately below the test panel so that
we could gain access into the room and
of course this meant crawling on hands
and knees each time a change in the test
procedure was required!
Although the test set-up was far from
perfect, decided that because many (if
not most) of the situations in which these
speakers are likely to be used, would be
far from optimum, then this test procedure would at least be realistic. As it
transpired, this approach proved to be
an acceptable compromise, and the
measured on -axis frequency response extended from 60Hz to 18kHz with two
significant measured notches, one of
which lay in the 80Hz region, whilst the
other was around 9kHz.
As was concerned that the panel test
might have introduced unwanted errors
into the testing, repeated the test with
the speaker mounted in a 30 litre vented
enclosure to reassess the performance
and specifically to see if the two notches
were still there. As you will see, the
notches weren't artifacts from the test
procedure, as the vented enclosure produces very similar characteristics. These
notches are apparently interference efI
I
I
Below is the
decay response
spectrum analysis
plot of a UNI-Q
associated with position of the
UNI-Q tweeter in the throat of the low
fects,
frequency driver's diaphragm assembly.
It proved easy to measure the speaker
impedance curve, which was extremely
smooth apart from a single resonant
peak at 60Hz, but it proved extremely
difficult and a most unrewarding exercise when we tried to measure the phase
response in the square panel. Surprisingly, apart from the two major reversals in
the phase response, which were directly
attributable to the non -sealed mounting
system, those measurements still confirmed that the phase response is still
very smooth and that the UNI-Q system
provides a generally good linearity apart
'funny interference problems'
from
which were observed in the 10kHz region.
The harmonic distortion measurements
revealed a relatively high level of 7%
distortion at 100Hz, a somewhat lower
level of 1.2% at 1kHz and a very low
level of only 0.17% at 6.3kHz.
Not surprisingly the CR160 speaker requires just under 13 watts of power to
produce 96dB of sound pressure level, at
one metre on axis in the panel test. This
is quite reasonable when you consider
the nature of the inefficient mounting
system that we chose for our first frequency response testing set-up. It will
also be typical of many, if not most, of
the potential systems in which these
speakers are likely to be used.
Although we had intended to produce
a decay response spectra analysis in the
panel, this could not be achieved with
the original testing set-up so we repeated
Measured Performance of KEF
CR160 Loudspeakers
Serial No:
Frequency response:
005814
As Fig.1
(on 1m x 1m baffle)
driver in an
enclosure.
Sensitivity:
8.8V/rms = 12.9 watts
(for 96dB average at 1 m) (nominal into 6 ohms)
Harmonic distortion:
96dB 96dB
90dB
(for indicated levels at 1m)
100Hz 1kHz 6.3kHz
on 1m x 1m flat baffle
2nd -23.2 -41.2 -56.0dB
3rd
-40.9 -41.3 -63.9dB
4th
5th
-45.4
THD
Input impedance
-
7.0
-66.6
-
0.17%
100Hz/7kHz 4:1
1.2
One Test
a
10
Frequency
15
20
100Hz
1kHz
6.3kHz
Min at
2kHz
25
- kHz
ETI
AUGUST '90
26
6.6 ohms
5.6 ohms
5.4 ohms
5.4 ohms
the test with the speaker installed in its
supplementary speaker enclosure. That
testing proved to be worthwhile as it
confirmed that the decay response spectra of the speaker still has its notches,
has a significant mid -range presence,
and exhibits two prominent decay resonances
one at 3kHz and the other at
20kHz.
had hoped to install the speakers in a
ceiling in my home, but following
remonstrations from the management
looked around for a more appropriate
and less controversial option.
This
loomed up in the form of a yacht. High
quality boat speakers happens to be a
major new US market and one that is
equally attractive in Australia. The market probably has even greater potential
in New Zealand, where it seems like almost every house has a boat. As
observed in Wellington recently, few of
these could be classified as small boats.
The new test bed for the CR160's was
'Pixie', a delightful new 11.5m long
yacht which has been lovingly constructed and is just the sort of place
where you would expect to find a good
sound system. Extra special care has
been applied in its construction to minimise noise, with the clear intention of
providing an environment for a sound
system which would be as close to the
'top of the class' as we could possibly
make it.
As many of you will realise, there isn't
really a lot of space in any sailing boat,
and there is generally even less space
available (or even suitable), for mounting
loudspeakers of the calibre of the
CR160's. The two spots that were selected for these built-in speakers were
only fair in terms of 'domestic criteria',
but these were the best that were available in terms of security of mounting
and adequacy of rear space
as well as
having the potential range of sound
coverage that would be simultaneously
achieved in both the saloon and through
to the cockpit.
The test of installing the speakers
proved to be simple, straightforward and
surprisingly fast. We were ready for the
subjective assessment in a couple of
hours, most of which was really spent on
cleaning up the saloon.
Fortunately, there was mains power
available at the dock side so decided to
use a Sony CDP555 ESD CD player coupled to a Sansui B77 stereo amplifier,
with inbuilt graphic equaliser and
matching power output display which
felt was most desirable in these special
circumstances.
decided to carry out some frequency
response measurements in the saloon of
the boat and recorded these using a
Bruel & Kjaer type 4133 microphone
was
of the sensational Japanese new
'Wunderkind' violinist with the catchy
name Midori, playing Dvorak's Concerto
for Violin and Orchestra (0P53) with
Zubin Mehta conducting the New York
Philharmonic
Orchestra
(CBS
MK
44923). This particular disc is one of the
most brilliant renditions of what is already regarded as being a brilliant violin
-
I
I
The tone burst response at 100Hz
(upper trace input, lower trace
output).
I
I
I
...and at 1kHz...
-
I
I
I
concerto.
Neither I nor the rest of the entourage
that I had gathered for my test programme on the yacht was quite ready for
the quality and brilliance of the sound
that Midori and the orchestra provided.
The two speakers were mounted quite
low and the front face of a combined
bench/berth, in the saloon of the yacht.
had initially felt sure that they would
prove to be less than satisfactory in
terms of sound, but was proven to be
wrong.
As each of us quickly discovered, you
could sit on the seat with the speakers
on either side of your legs, and the
stereo imaging of Midori's violin was not
lost. Even though the low frequency
sound was being generated beside you,
surprisingly there was no real loss of
high frequencies. These retained most of
their spatial directionality from the opposing sections of the hull and bulkhead,
which you were facing. Everybody who
sat on the bench voiced their satisfaction
with the speakers' position, as well as
with Midori's virtuosity, and each of
them expressed the desire to go out and
purchase this disc.
The second disc which I utilised for
the subjective appraisal was a new issue
of Arnold Schoenberg's 'Pelleas Und
Melisande', with Daniel Barenboim conducting the Orchestre De Paris (CBS MK
38557). This is a surprisingly lyrical,
equally memorable and quite outstanding disc. Schoenberg's sometimes heavy
style of music is for once graceful, light
and with softer presence which is somewhat atypical of much of his other
music. The orchestra projected from the
speakers with the full bodied sound of a
'real orchestra', and the majority of the
instruments, although not as spatially
well defined as in the Midori disc, readily rose to the occasion.
I
was rewarded with a level of 'deja
vu' that was sitting in a concert hall,
rather than sitting inside the small saloon
of a sailing yacht. It was an exciting feeling, for these speakers were not mounted
in custom built enclosures, but simply
panel mounted in the vertical bulkhead
of a pair of imperfectly sealed enclosures
with some pillows and assorted ship's
stores sharing their space.
The CR160 UNI-Q speakers are a significant and positive speaker development from KEF as they produce quality
...and finally at 6.3kHz.
with its pre -amplifier feeding directly
into a Sony PCM-2000 portable battery
operated DAT recorder. The 'as installed'
frequency response was measured utilising a CD test disc, which provided both
swept sine waves and pink noise for that
purpose. This facilitated a direct evaluation of the resonance characteristics of
the mounting system, checked the adequacy of speaker's fixings and also highlighted the need for some extra stiffening
of the supporting framework. Having
proven that the speakers were correctly
(and adequately) installed, quickly proI
gressed to the subjective testing.
The software chose for my evaluation
was a selection of standard test discs together with two exciting new discs
which had just received. The first disc
I
I
ETI AUGUST '90
27
I
Meeting the demands
of audio today,
setting the standards
for audio's future.
Destined to become yet another
classic bearing the KLIPSCH name,
the new KLIPSCH QUARTET embodies
time-tested design principles and
dawning technology to give you a
speaker system of the highest sonic
integrity. The QUARTET's new hybrid
troctrix midrange horn is uncanny in
its ability, to deliver the countless
inner details of complex musical
passages. Designed with computer
modelling techniques, the QUARTET
woofer Is voice-coil-vented to
increase power handling and bass
output while decreasing distortion.
The classically-styled cabinet of the
QUARTET is hand-finished in your
K
E
F
CR160
LOUDSPEAKER
MEASURED AT 1m
T1.EETER
ON
AXIS
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KEF
LOUDSPEAKER
AT lm
MEASURED IN A
30 LITRE VENTED
ENCLOSURE
U
AT 1.AA
INSTALLED IN
RULENEAD OF
THE YACHT
'PIXIE.
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Loudspeaker Technology:
u
I
-
Loudspeaker technology continues to evolve and develop
spurred on as ever by the insatible
urge, among designers and users alike, to approach ever more closely the ultimate goal. of
`perfect' sound reproduction. However as in the past this must usually be reconciled with
mundane practical considerations, such as the limited space and money available to many
which explains the multitude of resulting design solutions. Here Jim Rowe samples the
users
latest models and literature from many of the better-known manufacturers, to give you an idea
of the current state of the art...
-
INFINITY SYSTEMS
Founded in the late 1960's, this California -based firm has become well
known for its high quality loudspeaker
systems. However in 1982 it became
one of the undisputed leaders of the international industry, with the release of
the Infinity
its top of the range IRS
Reference System. As the name suggests this was intended to become 'the
ultimate' performance reference, against
which others would be compared. It was
handmade to special order, and had a
corresponding price tag: $45,000.
Today the IRS concept has been developed and expanded, into a complete
series of IRS models. At the top of the
range is the model V, virtually the latest
update of the original model, and with a
similar price. It is a four -piece system,
with two 'line source' midrange/tweeter
all
systems and two woofer modules
of which are over 2.2m high.
The IRS V woofer modules each use
six 300mm `IMG' drivers, with polypropylene cones reinforced with radially
aligned graphite fibres, driven by an inbuilt 2000W power amplifier and with a
motional feedback system employing a
piezoelectric `accelerometer' to sense
voice -coil motion. Equally impressive
are the midrange/tweeter units, each of
which uses a total of 48 ribbon -type
12 for the midrange, and 36
drivers
for the high frequencies. The ribbon
drivers use Kapton diaphragms with
photo -etched conductors, coupled with
high -efficiency neodymium magnets.
The midrange/tweeter units also feature
-
ou
-
-
Infinity Systems' top of the line IRS V System has two of these enclosure
pairs, with 48 ribbon drivers in the midrange/high enclosure (left).
large sand -filled `wings' on each side of
the driver panels, to reduce diffraction.
The model V is still a `built to order'
system, but the other models in the IRS
range are all normal production models.
Most impressive of these is the Beta,
ETI AUGUST '90
29
again with four separate modules needing bi-amp drive. Here the bass modules each feature four of the 300mm
IMG drivers, again with motional feedback, while the midrange/tweeter units
each consist of five of the `electromag-
has a single 300mm IMG driver with
motional feedback and an internal
250W amplifier.
Further Infinity models include the
Kappa series, the Studio Monitor SM
series, the Kappa Automotive series of
drivers for mobile systems, and the ERS
series of in -wall systems.
Further details of Infinity Systems are
available from the Australian distributors, Silver Australia, of 4 Rushdale
Street, Scoresby 3179 or phone (03)
763 0177.
Speaker
Technology
DUNTECH AUDIO
1
Infinity's very compact Modulus
enclosure couples a 140mm IMG
woofer with a ribbon tweeter.
-
netic induction' ribbon drivers
of four
different sizes, each catering for a different segment of the spectrum.
Below this are the Gamma and Delta.
models, each with a single cabinet per
channel. In both cases these feature two
of the 300mm IMG bass drivers coupled
with one each of the four different ribbon drivers, on each side. The Gamma
provides the same inbuilt bass amp/motional feedback system as the larger
models, while the Delta uses a normal
passive crossover for use with a conventional high -quality amp.
Other models in the current Infinity
lineup include the lower priced RS
Series. This has six models, with IMG
bass drivers of various sizes, a midrange
driver using a spherical dome radiator
coated with graphite microspheres, and
either a similar dome tweeter or one of
the ribbon tweeters used in the IRS
series. All models feature rounded
edges on the front, to minimise edge
diffraction. A matching RS Subwoofer
system features a 245mm IMG bass
driver and motional feedback via an inbuilt 100W amplifier, with variable
crossover frequency.
There's also the Modulus system, consisting of a pair of very compact 'bookshelfenclosures coupled with a sub woofer. Each of the smaller enclosures
has a 140mm IMG polypropylene/graphite woofer, with one of Infinity's k ribbon tweeters; the matching subwoofer
Coming closer to home, another
range of top -end loudspeaker systems
that has achieved international recognition is the Duntech series made in Salisbury, South Australia. Despite being almost unknown in its home country,
Duntech's flagship models have received
`rave' reviews in overseas magazines,
and are top sellers in the USA, Hong
Kong and West Germany.
Top of the Duntech range is the
`Sovereign 2001' system, selling for
$16,495, with other models ranging right
down to the `Little Duchess' system
priced at 11199, and the just -released
MRM-1 'Mini Reference Monitor' system priced at only $399.
Little technical information is available on the various Duntech models,
but the company stresses that great emphasis is placed on pulse coherency,
with simulated point-source radiators
and symmetrical radiation patterns. A
patented system of using absorbent material on radiating surfaces is said to virtually eliminate edge diffraction, while
computer -aided matching of drivers and
crossover network components
coupled with extensive computer -controlled
testing is said to ensure that all enclosures perform well within specs.
Further details are available from
Duntech Audio, PO Box 421, Salisbury
5108 or phone (08) 349 5188.
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-
APOGEE ACOUSTICS
Another US -based firm that has
placed heavy emphasis on ribbon driver
technology is Apogee Acoustics, of
Randolph, Massachusetts. However in
this case ribbon drivers aren't used just
for the midrange and high frequencies,
but for the full audio range. In fact
Apogee claims to be the maker of the
world's first and only full-range planar
ribbon loudspeaker system.
According to Apogee, the advantage
of its planar ribbon systems are complete freedom from box colouration,
faster transient response due to the ex ETI AUGUST '90
30
-
Apogee
Acoustics'
smallest
wide -range ribbon system is the
Stage, which is almost a metre high.
tremely light diaphragms, and extremely
low distortion. Judging by the superlatives used by reviewers to describe the
performance of Apogee systems, there
seems little doubt that they support the
firm's claims.
Apogee's midrange and tweeter
drivers are of reasonably conventional
`transverse' ribbon construction. A very
light vertical ribbon of Kapton, carrying
thin-film aluminium conductors, is suspended freely in a gap between magnet
poles on each side. However the bass
drivers use a different approach, with a'
much larger and wider ribbon carrying a
`zig-zag' conductor system, and a tensioning system which locates it accurately in front of an X-Y array of magnets, mounted on a heavy, perforated
steel plate. The magnets and conductors
are positioned so that the flux intercepts
the horizontal ribbon conductors vertically, and in the `up' and `down' directions respectively for 'zig' and `zag' conductors, so that the ribbon moves foreand-aft as a single piston.
There are four systems in the Apogee
range, with the top of the line being the
Diva system. This consists of two three ribbon speakers, each measuring 1855 x
788 x 75mm, and designed to operate
from 100W amplifiers. They have a
rated frequency response of from `below
25Hz to over 25kHz', and can produce
a sound pressure level of 118dB at 4m.
Next in line is the Duetta Signature
system, with a pair of two -ribbon speakers each measuring 1473 x 660 x 75mm
and with a rated frequency response of
below 30Hz to 20kHz.
Then there's the Caliper Signature
system, with two -ribbon speakers each
measuring 1220 x 610 x 50mm and a response from 30Hz to 20kHz. And finally the Stage system, with a pair of
two-ribbon speakers each measuring 940
x 660 x 50mm and a rated response of
35Hz to 20kHz.
Each of the Apogee systems has a
built-in passive crossover network giving
6dB/octave slope. However Apogee also
provides the optional DAX dedicated
active crossover unit, for the use with
all of the systems except the Stage. The
DAX has a fixed crossover frequency
(330Hz) and slope (6dB/octave gradually increasing to 12dB/octave), but allows adjustment of each driver level
over a 6dB range, in steps of 0.2dB
with digital readout. It also allows separate adjustment of overall 'rake angle',
for greater control over balancing for
room acoustics.
Further details on Apogee Acoustics
systems are available from Leading
Edge Audio, 49 Ramsden Street, Clifton Hill 3068 or phone (03) 489 0446.
-
GNP ACOUSTICS
Another respected Australian brand
is GNP Acoustics, of Reservoir in Victoria, which claims to combine the best
drivers with carefully deand hand-crafted enclosures.
GNP also places great emphasis on its
'no compromise' crossover networks,
which use air -cored inductors and close tolerance polypropylene and polystyrene
capacitors.
Top of the current GNP range is the
Connoisseur system, which uses a time aligned 6-driver four way system in each
enclosure. Two 250mm Focal Edge wound woofers are used in a push-pull
reflex bass system, with the 175mm
Focal midrange driver also featuring an
edge -wound voicecoil. A 25mm Focal
Concave Kevlar dome tweeter handles
the main treble range, while the extreme highs are handled by a pair of
ribbon 'super tweeters'. The rated response of the Connoisseur is 36Hz
European
signed
a single 200mm long -throw
woofer combined with one each of the
same midrange and treble drivers used
sures with
in the Connoisseur. It has a rated re25kHz, with a sensisponse of 38Hz
tivity of 91dB/1W/lm and a power handling capability of 200W.
More compact and lower priced than
the Reference Series are the 'Designer
Series' systems, with the largest of these
being the model 100. This has a pair of
985 x 260 x 290mm enclosures, each
with a two way configuration comprising
200mm Focal twin voicecoil woofer in a
bass reflex system, with a 25mm dome
tweeter. The rated response is 39Hz
-
-
19kHz (+1-4dB), with power handling
to 80W RMS and a sensitivity of
91dB/1 W/1m.
Other models in the Designer Series
are the smaller, but higher performance
`bookshelf models 150 and 200. The
150 measures only 450 x 228 x 210mm
and combines a pair of 125mm woofer/ midrange drivers with a 25mm inverted
dome tweeter to give a response of
45Hz
18.5kHz, with a sensitivity of
89dB/1W/1m and the ability to handle
up to 100W RMS. The model 200 is a
little larger, with enclosures 600 x 250 x
360mm housing three way configurations with a Focal Edgewound 175mm
woofer, 125mm Neoflex midrange and
25mm inverted dome tweeter. It has a
18.5kHz, a
rated response of 401-1z
sensitivity of 89.5dB/1W/lm and a
power rating of 125W RMS.
GNP also makes available the Ultimate range of subwoofer systems, to
augment and complement the Designer
series and similar systems. There are
four models in the range, ranging from
the 300 SW, with two 175mm drivers
-
-
-
of
sensitivity
93dB/1W/lm and a power handling capacity of 200W RMS. Its cabinet is
made from 25mm and 32mm high density craftwood, with lead lining and
heavy bracing to prevent resonances.
The other member of GNP's 'Reference Series' is the Grange system,
which has a pair of four -driver enclo40kHz,
with
a
-
=
The GNP Acoustics 'Gargantuan'
subwoofer system, 900mm high.
ETI
AUGUST '90
31
Also from GNP Acoustics is this
four-driver
widerange
'Grange'
system.
(one per channel) and designed to serve
as a coffee table, to the 'Gargantuan'
model with two 400 x 400 x 900mm enclosures each containing a pair of
250mm long -throw woofers in push-pull.
Further information is available from
GNP Acoustics, 2 Berwick Street,
phone
(03)
or
Reservoir
3073,
470 3171.
WHATMOUGH MONITORS
Still looking at local manufacturers,
Whatmough Monitors was founded over
15 years ago and became known to affia
cionados for its Mark II system
transmission
large (and expensive)
line/open baffle hybrid.
Currently the firm produces the
models 201 and 201 Export, both of
which use relatively compact 540 x 285
with optional
x 310mm enclosures
matching stands. Each has a pair of enclosures with a two way configuration,
using a 175mm dual voicecoil woofer
with damped neoflex cone coupled with
a 30mm Kevlar inverted dome tweeter.
However the tweeter in the 201. Export
model has a larger magnet, weighing
1.4kg, and also provides front and back
ventilation. In both models great attention has been paid to the crossover networks, which provide impedance compensation and feature heavy air -cored
inductors and German polypropylene
(201) or American 'audio grade' (201
Export) capacitors. The crossover networks are actually three way, with the
two woofer voicecoils driven by the bass
and mid -range signals respectively. The
crossover network in the 201 Export
model is also arranged for bi-amp drive.
Both models employ cabinets made
from braced particle board, internally
-
YAMAHA
Speaker
Technology
Yamaha
;WM
Above is Yamaha's AST -S1 enclosure
with the YST-SF50 enclosure below
Both are designed to take advantage
of the firm's 'AST' technology.
is
one of the more innova-
tive of the audio manufacturers based in
Japan, and its latest crop of loudspeaker
systems reflect the company's innovative
approach. They all incorporate Yamaha's new `active servo technology' or
AST principle, to achieve what seems to
be outstanding performance from very
compact enclosures.
Basically the AST concept seems to
hinge on a special power amplifier. Unlike standard amplifiers, where the output resistance is designed to be as low
as possible, the AST amplifier is designed to exhibit a negative output
resistance, with a carefully controlled
value which matches
and hence canthe pure `DC resistance'
cels out
component of the speaker voicecoil im-
-
-
pedance.
This results in extremely close coupling between the electrical drive and
the voicecoil's back-EMF, giving much
`stiffer' control of the cone motion and
a very high degree.of electrical damping
i.e., very low effective driver `Q'. As
well as lowering distortion the usual
bass resonance of the speaker cone assembly is virtually eliminated, so there
is much less need for the speaker's performance to be controlled by the enclosure.
The enclosure's own resonance can be
-
The Whatmough 201, another high
quality locally made system. It has a
175mm neoflex cone woofer.
lined with bituminised panels to suppress resonances.
Further details on Whatmough Monitors systems are available from Leading
Edge Audio, of 49 Ramsden Street,
Clifton Hill 3068 or phone (03)
489 0446.
ODYL GROUP
Before we leave the local manufacturing scene, the Melbourne-based Odyl
Group has just released a new wide dispersion full range system for building
into ceilings or walls. Fully developed
and manufactured in Australia, the
Odyl C300 system is patented; it is designed to mount flush with the surface,
extending into the ceiling/wall cavity,
and can be painted to match room
decor.
The single driver used has a flat Styrofoam diaphragm 300mm in diameter,
with an overall diameter of 350mm and
a depth of 65mm. With a rated frequency response of 401-z
18kHz
(+1-4dB), with a sensitivity of 90dB and
a power handling capacity of 40W
RMS/80W programme.
Further details can be supplied by
Odyl Group at 4/11 Molan Street, Ringwood 3134, or phone (03) 897 5111.
-
SONANCE
Continuing the theme of `built-in'
wall and ceiling speaker systems, the
pioneer in this area is Sonance, based in
San Juan Capistrano, California. In fact
Sonance is credited with producing the
first truly 'hifi' in -wall loudspeaker system, back in 1981. Since then the popu-
larity of so-called `architectural audio'
systems has grown dramatically, ' with
Sonance retaining a leading position.
Currently the company produces a
complete range of models, with the
highest level of performance provided
by the Sonance IV. This is a two way
system combining a SEAS 210mm polypropylene cone woofer with a VIFA
25mm polycarbonate dome tweeter and
3rd -order crossover network, in an assembly measuring only 375 x 270 x
86mm
capable of being fitted in a
wall with standard nominal stud depth
of 100mm. The front dress frame measures 410 x 308mm, and both the frame
and perforated metal grille can be
painted to blend in with any decor. An
alternative is to fit a cloth fabric, to
match curtains etc.
Rated frequency response of the So-
-
ETI AUGUST '90
32
IV is from 35Hz to 22kHz, on the
basis of it being installed in a betweenstuds cavity of a typical internal wall,
providing around 2.5 cubic feet of volume for the `infinite baffle' bass system.
The treble response also assumes the
appropriate setting for the built-in three
position tweeter level switch, provided
to allow compensation for absorption by
the cloth or metal dress grilles.
The Sonance IV is rated to handle up
to 100W, with a sensitivity of
90dB/1W/lm.
Other models in the Sonance range
include the models III, II and lA, all
with a cutout size of 304 x 229mm, and
responses of 45Hz
20kHz, 55Hz
20kHz and 85Hz
12kHz respectively.
There's also the compact model M30,
requiring a cutout of only 206 x 140mm,
and the model PSW2 subwoofer, with a
210mm dual voicecoil driver and requiring a cutout of 375 x 270mm.
Further information on all of the Sonance systems is available from the
Australian distributor Concept Audio,
of 32 Roger Street, Brookvale 2100 or
phone (02) 938 3700.
nance
-
-
-
designed purely to extend the overall
bass response beyond the speaker's
natural rolloff, allowing a relatively
small enclosure to produce surprisingly
good bass response. Yamaha calls this
the air woofer effect, as the enclosure's
port seems to act as if it were an independent 'second woofer'.
How is the AST amplifier arranged to
provide a controlled negative resistance
output? Yamaha hasn't released full details, but it would appear to be via a
system of deriving a positive feedback
component from the speaker's current.
An example of the performance which
the AST principle can achieve is provided by Yamaha's new AST-1 system.
This consists of a pair of very compact
enclosures
each only 297 x 230 x
188mm
driven by the matching two channel AST-A10 'Natural Sound Active Servo Processing Amplifier'. The
enclosures are two way systems, with a
160mm polypropylene cone bass/midrange driver and a 30mm soft -dome
tweeter. However the rated frequency
response is from 28Hz to 20kHz, with
an effective loudspeaker sensitivity of
112dB/1W/lm and a power output capability equivalent to 70W RMS per channel.
The YST-SF50 enclosures are larger
but thinner, each measuring 503 x 295 x
71.5mm and fitted with four 100mm
-
-
bass/midrange
polypropylene
cone
drivers plus a single centrally placed
30mm soft -dome tweeter. But when
driven by either the AST-10 amplifier
or Yamaha's new AX -630/730/930 series
of integrated amplifiers with the same
negative output resistance. feature, the
rated frequency response is a very impressive 25Hz
30kHz, with surprisingly powerful and crisp bass response.
Yamaha has also released the YSTSW100 subwoofer using the same AST
principle. In this case the special negative resistance amplifier is built into the
enclosure, making the system compatible with a wide variety of standard systems.
-
The subwoofer system uses a pair of
drivers with 'spruce -paper'
cones, and these produce an impressive
response from 21Hz to 180Hz with an
equivalent power output of 70W. The
inbuilt amplifier has a top -cut filter with
turnover adjustable over the range 40
140Hz and a fixed rolloff slope of
24dB/octave, to allow the system to be
matched to existing system and room
response.
Further information on this impressive
range of new systems is available from
Yamaha Music Australia at 17-33 Market Street, South Melbourne 3205 or
phone (03) 699 2388.
180mm
-
HATMOUGH
MONITORS
In
loud
MONITOR
WHATMOUGH
speakers offer extended frequency
response, superb imaging, remarkable
smoothness, and accurate tonality.
There are three models, starting at
$899 per pair.
MONITOR
also
WHATMOUGH
supplies two loudspeaker KITS, a 15
litre bookshelf at $695, and a 50 litre
floor -standing model at $975.
FEATURES:
World-renowned FOCAL drivers
Neoflex bass units with high -power 40mm edgewound voice
coils
Kevlar inverted dome tweeters
Solid, braced cabinets with bituminous panel damping
Hard-wired crossovers using polypropylene capacitors & air cored inductors
Kits have V -groove construction & easy assembly
WHATMOUGH MONITORS
4 Dianna Court,
Wheelers Hill
Phone: (03) 561 7027
Sonance 'architectural audio' wide -range speaker
system built into a typical internal wall. Sonance is
credited with producing the first 'hifi' In -wall system, in
A
LEADING EDGE AUDIO
49 Ramsden St.,
Clifton Hill
Phone: (03) 489 0446
1981.
ETI AUGUST '90
33
READER INFO NO. 25
Speaker
Technology
BOSE
air Mass
Another firm that has built its reputation on innovation in loudspeaker technology is Bose Corporation, based in
Framingham, Massachusetts. The company was founded in 1964 by Dr Amar
Bose, then and now a professor at
MIT's faculty of electrical engineering
- as well as Chairman of Bose.
Over the last 26 years Bose has firmly
established itself as one of the world
leaders in professional sound systems,
with wide -range and bass speaker systems that are exceptionally compact and
rugged. Its professional sound systems
are now very widely used in live sound
reinforcement for both indoor and outdoor events, as well as for the reproduction of recorded sound in movie and
live theatres, recording and film/TV studios. In fact Bose's compact wide -range
enclosures with their characteristic twin ported fronts are now quite possibly the
most recognisable loudspeakers in many
public buildings.
Quite early in the piece, the systems
produced by Bose were distinguished by
an emphasis on producing a combination of reflected and direct sound components. Bose has always maintained
that this achieves greater realism than
conventional systems, which generally
concentrate on direct sound only, but
debate about this continues.
In recent years Bose has come up
with a number of further innovations,
which are incorporated into its current
systems. Of these perhaps the most
widely known is the 'Acoustimass' principle, a development of the bass -reflex
configuration.
With a normal bass-reflex enclosure
the bass driver is mounted in the front
panel, so that there is direct radiation
from the front of its cone. Rear radiation is coupled to the air mass inside the
enclosure, which is used to control and
damp the speaker's natural resonance.
Tuning of the enclosure is via a port,
generally also brought out on the front
panel, and there is radiation from this
port which assists that from the front of
the cone.
With the Bose Acoustimass system,
the driver or drivers are mounted completely inside the enclosure, on a baffle
which totally divides it into two separate
compartments
each ported to the
front panel. In effect, both front and
rear cone surfaces are controlled separately by their own enclosure, with all
Bose's 'Acoustimass' principle uses fully enclosed drivers, with separate
enclosure volumes to control front and rear cone surfaces.
sound reaching the outside via the two
ports. Bose claims that this `filtering'
and damping by the twin enclosures
gives higher power handling capability,
lower distortion and improved efficien-
125Hz. The power handling capacity of
a single AWCS is 150W RMS or 300W
peak, with a sensitivity of 90dB/1W/lm.
The high efficiency allows the AWCS to
produce high levels of very clean bass
cy.
energy.
Bose has effectively taken the Acoustimass principle further again, in its
Acoustic Wave Cannon bass system, or
`AWCS'
effectively a subwoofer system for professional sound systems.
This is in the shape of a long cylindrical
tube, 3.8m long and 266mm in diameter, with .a single 300mm woofer placed
inside the tube at about 25% along its
length. The two unequal lengths of tube
coupling each cone surface to the outside form 'tuned acoustic waveguide'
resonators, controlling and filtering
cone movement.
Superficially one might expect this to
result in two pronounced output peaks,
but by careful acoustic design and the
use of electrical equalisation in the drive
system, Bose has been able to achieve
essentially flat response from 25Hz to
In a sense part of the secret to Bose's
success with both the Acoustimass and
AWCS systems is the use of active
equalisation
the use of tonal adjustment in the amplifier system, to compensate for the frequency characteristics
of the loudspeaker system and give a
balanced overall result. The same idea
is apparently also used to achieve optimum results with the company's compact wide -range systems, which tend to
use an array of wide -range drivers
-
-
rather than the conventional woofermidrange -tweeter lineup.
Incidentally Bose makes its all of its
own drivers, which use a rugged construction and heavy duty edge -wound
aluminium `helical voicecoils' - dubbed
HVC. From Bose's literature it's not
clear exactly how these differ from normal voicecoils, which are almost always
helical, or especially from those that are
made from edge -wound strip conduc-
tor...
Representative examples of current
domestic systems available from Bose
are the Acoustimass-5 system, which
1
J
-
The Bose 901 Series VI system, with
nine 114mm drivers per enclosure
eight facing towards the rear.
ET! AUGUST '90
34
-
combines two tiny 187 x 117 x 92mm
'twin cube' mid/treble units with an
Acoustimass subwoofer module; and the
901 Series VI system, which consists of
a pair of wide -range units each using an
array of nine 114mm wide -range drivers
- eight of which face towards the rear
to produce the reflected sound component, and driven by a matching active
equaliser unit.
Bose has also recently released a new
Professional Powered Loudspeaker System, which combines an array of six
Small Cone Movement
'
*Pi II
<
r
Large Air Movement
1
ar-iLarge
Air Movement
Note: the open ends of the air columns are in phase.
Bose's 'Acoustic Wave Cannon' bass system, an innovative 3.8m long
subwoofer enclosure for professional sound systems.
114mm wide -range drivers, a 300mm
woofer in an Acoustimass bass system,
and a built-in 450W switch -mode amplifier
all in a package measuring only
591 x 565 x 406mm, and weighing
36.4kg.
Further information on all of the Bose
systems is available from Bose Australia, 11 Muriel Avenue, Rydalmere 2116
or phone (02) 684 1255.
-
MONITOR AUDIO
Based at Cambridge in the UK,
Monitor Audio initially made its name
with loudspeaker systems using other
firms' drivers. However in recent years
the company has developed its own innovative drivers, including a gold -anodised metal dome tweeter.
s
Now MA's designer/founder Mo Igbal
has launched a new range of metal
coned bass/midrange drivers. These are
made using a three -stage process, where
the metal is drawn to a final thickness
of only 100um (0.1mm), and then electrically coated on each side with 50um
layers of ceramic material. This is described as providing damping to the
cone
plus stiffening, as the first cone
breakup mode doesn't occur until over
6kHz. A hard, synthetic phase -correcting plug is mounted in the centre of the
cone, while the inverted roll surround is
made from high compliance nitrile rubber.
MA's new Studio 10 system partners
one of the new drivers (a 170mm
model) with its existing metal dome
-
tweeter, in a compact 400 x 250 x
200mm bass -reflex enclosure.
The
quoted response is 40Hz
20kHz, a
sensitivity of 88.5dB/1W/lm and an
power handling capability of 200W.
Further information on Monitor
Audio's drivers and systems is available
from the Australian distributors Audio
2000, at 137 Victoria Road, Drummoyne 2047, or phone (02) 819 6533.
-
SUMMARY
I hope this sampling from the latest
model loudspeaker systems and drivers
has given you at least an idea of the
current state of development in loudspeaker technology. Audio technology
as a whole is not an easy area to summarise, because of its inherent conflict
between objective and subjective considerations.
In particular the objective aspects of
developments in speaker technology can
be exceptionally difficult to grasp and
understand, due to the enveloping
'smog' of marketing hyperbole. There
are significant developments, as you can
hopefully see from the above, although
these are probably best described as
'evolutionary' rather than 'revolutionary'
despite the understandable enthusiasm of marketing and sales people.®
-
Aud/11
Monitor
Audio Ltd
Symbol of Quality
LISTEN TO THE WORLD'S MOST
ADVANCED LOUDSPEAKERS.
With Studio 10, Monitor Audio has developed a loudspeaker system that advances
further the developments begun with our first metal dome high frequency driver.
Because Studio 10 incorporates a unique ceramic sandwich metal cone low/mid
frequency driver.
The new low/mid driver provides a quality of music reproduction simply
unavailable elsewhere. Clarity and naturalness combine with outstanding speed and
accuracy bringing true realism to recorded music.
But while the significance of our new development in driver technology should
not be under emphasised, performance in the vital mid -range spectrum must be
matched equally at higher frequencies, otherwise the design will be unbalanced. Our
gold anodised alloy dome high -frequency driver provides such balance with style.
Integrated with an audio system of equal quality, mounted on its dedicated stand
and installed sympathetically in a listening room; Studio 10 becomes a complete,
balanced instrument of music.
M1
FOR FURTHER INFORMATION AND THE NAME OF YOUR NEAREST SPECIALIST DEALER
PLEASE CONTACT:
AJ14 O4
Rogers
BAITISH
HIGA FIDELITY
P.O.Box 94, Drummoyne, 2047. Ph: 819 6533, Fax: 819 6312
/4 ERIDIAN
J A Michell Engineering Ltd
GYRODEC TURNTABLE
ETI AUGUST '90
35
GRADO
CARTRIDGES
Hunt EDN.
CD & RECORD CLEANERS
READER INFO NO. 26
HITACHI'S NEW
FLIP -TOP LAPTOP VCR
Yes, it sounds a little like something from a Clive James TV show, but Hitachi's new
VT-LC5OEM really is a flip -top, laptop, all colour, multistandard, self contained, pick it up and
carry it along VHS video recorder and TV receiver combination. About the only thing that's
lacking is the satellite dish and downconverter!
by. LES CARDILINI
-'"
i
+',:i
,,, ,
_
=^ '
`u .__fi
Released in Australia during May this
year, Hitachi's new laptop VCR model
VT-LC5OEM is possibly the first portable VHS VCR to reach us with its own
built-in picture and sound.
The VT-LC5OEM weighs only 3.4
kilograms and is not much bigger than a
attache case or handbag, but it handles
full-size VHS videocassettes.
The laptop follows hot on the heels of
Hitachi's innovative automatic head
cleaning model, and is perhaps better
described as a video deck: a compact
AC -DC portable multi -system VHS
VCR and TV receiver combination
complete with telescopic TV antenna,
loudspeaker sound and a retracting
carry handle for total mobility.
The set has some obvious attractions
as a personal AC-DC portable VHS
VCR-cum -TV set for, say, hospital patients or for domestic or business use.
But the VT-LC5OEM has a number of
additional features that should appeal to
both travellers and anyone who requires
to play video recordings made in countries with different TV standards from
our own PAL system.
This new Hitachi video deck automatically handles videocassettes recorded in
the various video formats used around
the world, including PAL, SECAM and
the NTSC system which serves Japan,
Canada and the United States of America.
Having video recordings `translated'
from one video format to another can
as a rule be a relatively expensive exercise, especially if it is necessary to do so
on frequent occasions. A multi -system
VCR at the ready helps to avoid the inconvenience and expense of having
tapes translated for viewing, particularly
in out-of-the-way places and at very
short notice. Business agents and -consultants, for example, might find a machine like the VT-LC5OEM to be a very
handy addition to the communications
resources kit.
The VT-LC5OEM laptop VCR can
also be used to watch and (where copyright laws 'permit) record local television, while on holiday or business trips
overseas. The set's inbuilt TV tuner can
be switched to receive PAL and
SECAM TV broadcasts in Europe,
China and the USSR, The Middle East,
One
Top and above: two views of Hitachi's compact new VT-LC5OEM portable VHS
recorder/TV receiver combination.
ETI AUGUST '90
36
Asia and Australia.
(The VCR will play back tapes recorded in the NTSC system used in
Japan, Canada and the US, but it is not
designed to receive the regular TV programs broadcast in the NTSC standard,
off-air. However, NTSC recordings can
be made using the VT-LC5OEM by connecting a suitable cable between the
Video Out socket on an NTSC monitor style TV set or an NTSC VCR, and the
video input socket on the VT-LC5OEM.
For practical purposes it should be as
easy as interconnecting two PAL VCRs
at home.)
Potential problems with different AC
mains voltages and frequencies in other
countries are also minimised with the
VT-LC5OEM, which may be operated
on its rechargeable NiCad battery pack
or from the AC mains using the power
universal AC mains adaptor -charger
that comes with the unit.
The AC adaptor supplied with the
VT-LC5OEM automatically adjusts to
the AC mains voltage and frequency.
This helps to avoid those nasty and
often expensive little accidents that
might occur due to lapses in concentration - when, for example, jet -lagged
travellers plug mains operated appliances into unfamiliar mains sockets. A
DC power lead is also included for connecting an external 9.6 volt battery or
DC power source.
The rechargeable NiCad battery supplied with the VT-LC5OEM has a caof 2000
milliampere -hours
pacity
(mA.h), and clips securely in place on
the back corner of the video deck to
power the set on DC. It also lowers the
centre of gravity for added equilibrium
when the VT-LC5OEM is placed down,
briefcase style while it is on field duty,
as a portable. A moulded battery cover
keeps the battery out of sight and maintains the cabinet's lines and general appearance.
To operate the VT-LC5OEM from the
AC mains the AC adaptor -charger supplied with the set is plugged into the
mains and connects to the deck via a
DC lead plugged into the 9.6V external
DC socket. Adjustment to the applied
AC mains voltage is automatic within
the range 100-240 volts and for either
50Hz or 60Hz mains frequency. The
NiCad battery is recharged by removing
it from the video deck and simply clipping it to the side of the adaptor -charger, before switching on the mains.
A smaller, 3 volt lithium battery (CR 2025 or equivalent) is used as a backup
for the internal time -of-day clock and
TV channel tuning memory when the
set is otherwise switched off. This
r
t
1
.1
closeup look with the transport lid raised, with the head drum partly visible
in the centre. It takes full-size VHS cassettes.
A
should hold the correct time and preset
channel memory for approximately one
year, according to specifications provided with the set.
When the lid is opened on the VTLC5OEM, up pops the slim 127mm (5")
full colour LCD (liquid crystal display)
picture. At the same time the accompanying sound from the TV or videotapes
can be heard through the set's own amplifier and loudspeaker, or headphones
if preferred. For larger -screen viewing
the VT-LC5OEM may be connected to a
regular TV set or monitor system, like a
'conventional' VCR.
The LCD screen is switched off automatically to save the battery, when the
display lid is closed over the operator
panel. This includes the regular VCR
controls and TV tuning plus display
functions.
Sleep and wake-up timers and programmed recording are also featured in
the VT-LC5OEM, and the time of day
can be called up promptly in the display
and superimposed briefly on the picture, if required. The on -screen display
can also be switched to show other information such as the TV system mode
selected, playing times and VCR status
and which channel is currently selected
from the memory TV tuning.
Up to 20 preset channels in the various PAL and SECAM VHF and UHF
TV systems can be stored in the set's
TV tuning memory, and depending on
the quality of TV reception in a particular area the VT-LC5OEM laptop VCR
may be operated on its own telescopic
rod antenna or, alternatively, from an
ETI AUGUST '90
37
external antenna using a two-way split ter accessory supplied with the set and
the conventional coaxial RF IN, or antenna socket on the back of the VTLC5OEM.
Long play and standard play VCR
speeds provide videocassette playing
times up to 480 minutes (PAL long play
mode.)
Audio and video input and output
connectors, also mounted on the rear
panel, can be used for dubbing or
recording with other VCRs and for
recording and playing back tapes with
monitor style systems. These are selected via the Line -Tuner switch button
on the main control panel.
Two earphone sockets are also provided, for personal listening to TV or
video sound. Using one earphone
socket disconnects the internal loudspeaker in the video deck. The other
earphone socket does not interfere with
speaker operation. The set has its own
volume control.
Picture clarity provided by the
114,240 picture elements (pixels) in the
liquid crystal display on the VTLC5OEM is enhanced by fluorescent
back -lighting, which enables the screen
to be used in bright and subdued ambient lighting and the dark. This contrasts
with the limitations of LCD displays in
watches and calculator displays, for example, which have reflective panels behind their displays and depend on relatively high levels of ambient light for
brightness and clarity.
Besides being much flatter and lighter
in weight than conventional TV picture
Hitachi's Laptop VCR
A TRIP BACK
la TIME!
.
The.-~Mtnlas
I RE
.......
t`
o
_.
-
(ti1Lu1Ltlyo
j
Y
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tE41
mr IM7 awni oak r t7 Hi
MOW /Myl. mew «7195. ,ia/f //úos
Two further
views of the
popular
demand,
we've
reprinted our nostalgic look at the
radio scene in 1927. If you missed
it the first time, don't miss it this
time around...,
By
VCR, showing
the right-hand
end (above) and
the screen/control panel. The
5" LCD has builtin backlighting.
Available for $5.95 (including
postage and packing) from
Electronics Australia
Reader
Services, PO Box 227, Waterloo
_..1111.,
MN.
2017.
in weight
MAGAZINE
Rec°rngMusicians,
Engineers, Road
Li
Crews,
restedhtgoes
ie,Mana
music-snaking.intodays
d/°Iri'
N
ETI
than conventional TV picture tubes, LCDs of
course require significantly less power and are therefore
more ideally suited for use in battery operated video systems
with small picture screens.
Picture brightness and contrast provided by the LCD panel
on the model reviewed was more than adequate for viewing
in normal ambient light.
Natural colour was adjustable through a wide range of
saturation levels. The indexed brightness and colour controls,
together with a tint control for NTSC color reception, are recessed into the side of the lid housing the LCD screen.
The lid may also be tilted backward or forward, to avoid
unwanted reflections in the screen and affords a wide range
of viewing angles, such as might be required between placing
the video deck in the viewer's lap or on a table or desk.
A 14-page instruction manual printed in English clearly
identifies features on the VT-LC5OEM and describes how to
adjust functions such as the timers, preset tuning and automatic programming. Details for multi -system operation are
also provided in the hand manual.
Measuring just 370 x 89 x 215 (w x h x d) millimetres, the
Hitachi laptop multi -system VHS VCR and 12.7cm (5") LCD
colour television model VT-LC5OEM is in the hand luggage
you will find bigger radio -cassette recorders.
class
Recommended retail price for the VT-LC5OEM, including
accessories, is $3499, or $2300 duty-free to approved buyers.
The set is covered by a 12 -month warranty.
Further information may be obtained from Hitachi Sales
Australia, 153 Keys Road, Moorabbin, Victoria 3189 or
phone (03) 555 8722.
-
AUGUST '90
38
The New 1990 Model
Hitachi breaks the sound barrier Acoustic Super Woofer in a portable unit.
Hitachi CX-W700W offers sound quality equal to that of many
mini -component systems in a portable unit. You get a
remarkable 200W (PM PO) audio output with powerful, solid bass,
plus the full benefit of CD digital sound.
CD Player: The optimum quality of digitally recorded sound
demands a high level of performance from the amplifier and
speakers. Hitachi CX-W700W delivers the wide
frequency response needed to get the most out of CD
recordings.
Home Music System: Hitachi CX-W700W is equipped
with radio, twin cassette decks and a CD player. So
whatever your choice in listening pleasure, this single
compact unit will meet your needs.
New Acoustic Super Woofer System
Equipped with its own 3D amplifier, this new
system meets the performance standards needed
for high -quality digital sound. And by scaling the
super woofer in a rear chamber, reverse phase
frequencies arc prevented from interfering with
low -frequency output ensuring clear, rich bass.
200W (PMPO) audio output
New 3D Acoustic Super
Woofer system
Two full -
range l2cm speaker
Surround
sound system
Three -band
graphic equalizer CI) Player:
32- program random nktiaxy LCD
track number display CD Play
/Itoc.Synchro CawIte Decks: Auto
Reverse (on Tape
High -s ed
I)
AutoStop & Nor,005 tape
Mic mixing with
volume control.
dubbing
selector (on Tape 2)
3BASS1[111
ACOUSTIC SUPER WOOFER
DIGITALAUDIO
-
t .
-
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(,deP
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UMW
cx-w700w
Portable 4 Band Radio/Stereo Double CassetteRecorder/
CD Player with 3D Super Woofer
z,_ '__1,.-=
am-='-
HITACHI
Victoria: (03) 5558722 New South Wales (02) 6663088 Queensland: (07) 2601344 South Australia: (08) 347 1234 Western Australia: (09) 277 9955 Tasmania: (002) 72 5651
Ad.dam Design 4491
READER INFO NO. 28
.
Circuit
Design Ideas
Interesting circuit ideas from readers and technical literature. While this material has been checked as far as possible for feasibility, the circuits
have not been built and tested by us. We therefore cannot accept responsibility, enter into correspondence or provide further information.
Car alarm protector
12V
While installing an alarm in a friend's
car, I realised that it could effectively
be disabled by merely cutting the wires
to the keyswitch on the dash. The attached circuit was devised to prevent
this occurring.
The base of the BC547 is held low by
a sense loop that is wrapped around the
keyswitch wires (as shown) before taping the bundle. If the bundle is cut or
torn from the switch, the base of the
transistor goes high via the 68k resistor.
This turns on the SCR through the two
10k resistors.
The SCR ensures that power to the
alarm is preserved. At the same time, a
KEY
SWITCH
ALARM
INPUT
KEY
SWITCH
SENSE
LOOP
ALARM
SENSING
LOOP
POWER
HE ATSHRINK
TUBING OR
TAPE
high is sent to retrigger the alarm (if
necessary). If your alarm inputs require
more than 0.2mA, then either a smaller
resistor may be used or a buffer transis-
Current consumption is less than
0.2mA when untriggered.
The circuit should be mounted within
the alarm case, except of course, for the
sensing loop.
Leon Miguel,
Hope Valley, WA.
$35
tor. Cl protects the circuit from ignition
spikes, while C2 and C3 protect the
SCR from switch pulses.
Novel `decision maker'
1M
PROBES
01
BC557
1N4001
BC337
6V
+ 5V
-4. AA
NICAD.
BATT.
o
z ..or E
QÑ
BUZZER
Water level alarm
With this gadget there is no more
overflowing tubs and sinks. When the
water reaches the probes, 01 gets base
current via the 1M resistor and the
earth path and conducts. This then allows current to flow from .the positive
rail to the base of Q2, and turns on the
6V buzzer (an L7009 from DSE was
used here). The diode protects the circuitry from EMF produced in electromagnetic buzzers.
In my case, the gadget is powered by
4 x AA Nicads, and is quite loud
enough. The components 'fit neatly into
a UB-5 case with the buzzer on top.
The probes are heavy insulated wire,
poking through the case and bent into
whatever shape is required to hang onto
a tub, sink, etc. The circuit needs no
switch and one charge ought to provide
over a thousand warnings.
Rolf Sommerhalder,
Rylston, NSW
$35
110
A while ago I was asked to make a
decision maker, for a boss who was
leaving. So I came up with this novel
circuit. Although it is a simple circuit, it
has two extra features:
1. The 'too hard' LED flashes.
2. It has auto power ON/OFF.
When SW1 is pressed, Cl charges up
via the diode and IC1a pin 3 goes low.
The transistor turns on and supplies
power to IC2. At the same time SW1
enables oscillator IC1b, which clocks
IC2 at high speed. When SW1 is
released IC1b is disabled and one of
IC2's outputs remains high turning on
one of the LEDs.
ELECTRONICS Australia, August 1990
SW1I
If pin 3 remains high oscillator ICld is
enabled and the 'too hard' LED flashes
at about 2Hz. Otherwise one of the
other LEDs will operate.
About 10 seconds after SW1 is
released, Cl discharges via the 1M
resistor. Pin 3 of IC1a returns high and
turns off the transistor, removing power
from IC2.
IC1c is used to invert the high from
pin 4 of ICIb and present a low to pin
14 of IC2 so that when power is removed from 1C2, its input does not exceed its supply voltage.
Lindsay Kafer,
Leichhardt, Old.
$
9V
©
BATTERY
1
1N1.148
Ir
BC327
V
7
T00 HARD -
1.70
ClrF _
1M
r
16
VDD
t3
01
12
11
13
IC2
I
4017
9
d
IC1c
10
1
14
100 k
10
1nF
100k
0212
05
4
3
RESETCK
IINHI
BIT
YES
NO-
03
04
7
470
MAYBE-
If you've developed an interesting circuit or design idea, like those published, why not send
us the details? As you can see, we pay for
those we publish
not a fortune, but surely
enough to pay for the effort of drawing out your
circuit, jotting down some notes and sending
the lot, together with your name and address to
Jim Rowe, Electronics Australia, PO Box 227,
2A
-
7'SA
200VA
1N4004
620 /10W
RELAY
3.9k
109F
5QV
32V
Waterloo 2017.
ó
T
(26v
COIL)
22k
2500íF
E
HEATER
ELEMENTS
B0139
-
This electronic thermostat circuit was
produced to allow seedlings to be grown
in the cooler winter months, here in the
mountains.
The circuit is fairly straightforward,
the 32V transformer being used as a
safety precaution in the wet environment of a hothouse. The heating elements are made from old electric blankets, but any kind of element would be
OK as long as suitable power can be
supplied by the transformer.
Temperature control is by the NTC
thermistor, with adjustment of the
switch -on temperature via the 10k pot.
The 470k resistor between pins 6 and 3
of the 741 give a hysteresis of approximately 1.9°C, which is narrow enough
for growing seedlings in winter.
M.R. O'Neill,
Blackheath, NSW
10k
63V
Seedling heater
thermostat
SEEDLING
BED
r
10k
NTC
22k @10°C
L
12V
400
mW
.5V
5V
67k
3
1k
1C2
STR
10NF
s8
527
CAS
15
B
2
15
76C922xiI11
1GnFLCE
T
1
1N914
EARTH
%1
10
VI
TC OUT
$45
IC1
so
5
6 01TC
-1-
7
16
sC
TA NTT
POUTS -
X4
17
A
73
--_J
i2.2yF
6
118
9r
I
THERMISTOR
2.2k
oc
52
r33
ITT
DA
p
p
P
MATRIX KEY PAD
67k
COMMON
10k
IC1
8C548
IC2
IC3
KEYPAD ENCODER
BCD RATE MULTIPLIER
TIMER
Serial keypad encoder
INPUT
OUTPT
E
M3
SOCKET
C=0.1NF 1000V
M1=275V MOV
M2= 75V
L1,2=100T
MOV
OF 26SWG ON
228-242 FORMER
Tuned mains filter
Here is a mains filter circuit that I developed to ensure reliable operation of
my firm's computers. There are many
such circuits, but in our area the
1050Hz tones used to control hot water
systems proved to be a problem, and we
needed to achieve better rejection of
this frequency.
The inductors each consist of 100
turns of 24SWG enamelled copper wire,
wound on a Radiospares 228-242 former
(6 layers, full bobbin). They have a Q
of around 40 and an inductance of close
to 2.3mH, so that if the shunt capacitors
are close to their nominal value
10uF, they will resonate at 1050Hz.
of
All capacitors marked C are
0.1uF/1000V types, and should ideally
be of the self-healing dielectric type for
AC mains operation. MOV varistors
M1 should be rated at 275V, while M2
should be rated at 75V. Needless to say
the entire circuit should be housed in either a fully insulated box, or preferably
an earthed metal case to prevent radiation from the inductors.
Paul Spresser,
Morningside, Old.
$30
For one of my projects, I required a
simple keypad which had to be small
and compact with a serial output. This
one works well!
A keypress produces a binary output
on ICI, which in turn sets the inputs on
IC2, dictating the number of pulses to
be produced at the output of IC2.
At the same time, a pulse is produced
at the 'data available' output, pin 12 of
ICI. This turns the transistor on,
grounding CE -bar on IC2.
Tc then goes low, keeping CE -bar
low, even when the transistor is turned
off. The pulses then appear on the output (pin 6) of IC2.
Tc returns to a high state at the end
of the pulse cycle, disenabling IC2,
which is reset and ready for another
keypress.
IC3 dictates the speed of the pulses.
All unused inputs on IC2 are grounded.
I have found this project to be useful
also, as a piece of test gear, when a set
number of pulses are required.
David Kadow,
$40
Plympton, SA
ELECTRONICS Australia, August 1990
111
Construction Project:
Flexible low cost
CMOS/IlL Logic Probe
Here's an easy to build logic probe design for troubleshooting in digital circuitry. It will operate
in either CMOS or TTL circuits, with supply voltages between 5V and 15V, and has a choice of
either 'stretching' or 'latching' for detecting short pulses.
by JIM ROWE
LOGIC PROBE
."'O
wat unw Ytrwowcs
enough to allow making one for the service kit, as well as for the home workshop bench.
As noted, the design for the probe.
comes from Dick Smith Electronics.
This means that the PCB pattern and
LED/switch panel designs are proprietary, and can't be supplied by other
firms. Individual readers are of course
free to make their own if they wish, but
in any case DSE is marketing a complete kit for the project, with the designation K-7405 and priced at only
$24.95.
tr.
..j. ",
Circuit description
A logic probe
is very handy when
you're trying to track down faults in
digital systems. With level indicators
right near the probe tip, it allows you to
check critical logic levels much faster
than with more sophisticated instruments like a logic analyser, oscilloscope
or DMM
and without getting sore
-
neck muscles!
The other main advantage of logic
probes is that they're relatively low in
cost. This even applies to many commercially marketed models, although
some are still pitched at a price level
that makes them rather more attractive
to companies than to private individuals...
Of course the way to get a logic probe
for the best possible price is to build it
yourself, as with many other test instruments. This also has the advantage that
having built it, you're generally able to
be more confident in its operation
or
at least, you're better able to fix it, if a
fault should develop.
Over the years Electronics Australia
has described a number of logic probe
designs. As it happens I myself de-
-
112
scribed our first very simple design, way
back in the October 1972 issue. Later
designs followed in the December 1974
and March 1979 issues, but surprisingly
the latter was our last
until now.
Needless to say things have changed a
tad in the last 11 years, so that perhaps
it's high time we came out with an updated design. And here it is, courtesy of
the R&D Department at Dick Smith
Electronics.
Based on a single LM339 low power
quad comparator IC, the new design
gives reliable indication of logic 'high'
and low' levels in both TTL circuitry
operating from the usual 5V supply, and
CMOS circuitry operating from supplies
anywhere between 5V and 15V. It also
has a stretching/latch circuit which can
either stretch narrow pulses to make
them more visible, or use them to trigger a latch for more reliable indication.
All of the circuitry for the new probe
mounts on a compact PC board, which
fits inside a neat little moulded probe
case. The whole thing goes together
very easily, to produce a sturdy and
practical testing tool
at a cost low
ELECTRONICS Australia, August 1990
-
-
The circuit consists of three basic
functional sections: a logic level 'window' detector, a pulse detector which
can function as either a monostable or
latch, and the LED indicators.
The logic level window detector is
formed by the two comparators Ula
and Ulb
both sections of the LM339.
The upper and lower limits of the 'window' are defined by the voltage divider
formed by R4, R5 and R6.
TTL and CMOS devices do not use
the same voltage levels for logic '0' and
'1'; the minimum '1' or high logic level
in particular is different, as a proportion
of the supply voltage (see Table 1). As
a result, it is necessary to adjust the
window thresholds for the two kinds of
logic family. This is performed by the
CMOS/TFL switch SW1.
In CMOS mode, R7 is paralleled with
R6 to make the upper window threshold
2/3rds of the supply rail. On the other
-
hand in TTL mode, R6 alone sets the
upper window threshold at slightly less
than 1/2 the voltage rail
in this case
5V.
Note that CMOS is run from supply
rails normally between +5 and +15
volts, and its high and low logic levels
-
are relative to its supply rail. TTL in
contrast is always run from +5 volts,
and its Hi and Lo levels are always the
same. Needless to say, to ensure correct
operation of the logic probe it is neces-.
sary to operate it from the same power
supply rails used to run the circuitry
being tested.
When the input to the logic probe is
floating, its input probe is held at a
level between the limits of the detection
window, by the voltage divider formed
by Rl and R2. This voltage is coupled
via series protection resistor R3 to the
`-' input of Ula and the `+' input of
Ulb. Hence in this condition, or if the
probe tip is connected to a voltage between the maximum Lo and the minimum Hi levels, the input voltage will be
inside the window determined by the
reference voltage divider (R4, R5 and
R6 or R6//R7). In this case neither comparator will turn on, and so the outputs
of both will be held high by R8 and
R10.
Note that the LM339 comparators
have open -collector type outputs, which
can only pull low. They only do this
when the voltage at the `+' input becomes negative with respect to that at
the `-' input.
If the probe tip is connected to a voltage which is higher or lower than the
window limits, the output of one of the
comparators will become low, and one
or other of LED1 or LED2 will illuminate. This, then, is how the probe indicates steady logic levels; now let us consider pulses.
Let's assume that the probe input
consists of a positive -going pulse, which
starts at 0, goes to 1 briefly, and returns
to O. The initial low level turns Ulb on,
so its output is low; meanwhile Ula is
off so its output is pulled high by R8.
Therefore C4 is charged via R11, while
C3 remains discharged.
At the pulse transition to 1, the output of Ula goes low, while that of Ulb
goes high. The positive -going edge from
Ulb adds to the charge across C4, and
D4 conducts
passing a positive -going
pulse to pin 4 of Ulc. The pulse lasts
until C4 is discharged, through D4 and
D5 and finally by R11.
When the original input pulse returns
to 0, a similar process may take place
providing the pulse duration has been
long enough for C3 to have charged via
R9. This requires about 1 millisecond.
For pulses of around this duration or
longer, the end of the pulse will cause
C3 to pass a second positive -going pulse
'on', with C3 charged, and Ulb 'off
with C4 discharged. On the arrival of
the pulse Ula will turn off, feeding a
pulse to Ulc via D3, while at the end of
the pulse Ulb will turn off and (if the
pulse has been long enough for C4 to
charge) feed a second pulse via D4.
So the combined effect of the circuitry
around C3, C4, D3 and D4 is to feed
either one or two positive -going pulses
to Ulc, regardless of whether the input
pulses are positive- or negative -going.
The fact that two pulses are produced
when the input pulses are longer than
about lms is something of a bonus.
The voltage divider formed by R16
and R14 keeps pin 4 of Ulc normally at
half the supply voltage. On the other
hand pin 5 is normally held near the
positive rail voltage, by R17.
During the positive -going pulses fed
via D3 and D4, pin 4 of Ulc is briefly
taken to a level above that on pin 5.
The level reached is clamped by D5,
but it is positive enough to make the
comparator switch
causing its output
go low. And when it goes low, the
negative end of C5 is pulled low with it,
causing CS to commence charging via
-
-
to Ulc via D3.
Input pulses of approximately lms
duration or longer will therefore cause
two short pulses to be fed to Ulc, while
those much shorter than lms will only
produce one pulse.
The main idea of having the two R -C
circuits and diodes is not to produce
two pulses from each input pulse,
though. It's really to allow the circuit to
respond to negative -going pulses, as
well as those that are positive -going.
Operation with a negative -going pulse
superimposed on a steady 'Hi' level is
very similar to the sequence just described for a positive -going pulse. The
only difference is that Ula is initially
-
R17.
The charging current of C5 pulls the
pin 5 of Ulc down below the level of
the R14/R16 divider, ensuring that the
comparator stays in its switched state
after the incoming pulse has ended.
C5 charges relatively slowly via R17,
due to the relatively long R -C time constant. Once the current falls and the
voltage at pin 5 rises above the level at
pin 4, the comparator will switch back
(SUPPLY VOLTAGE)
D10
(SUPPLY VOLTS -0.6V)
(.3V1
,LED2
LED2
120k
820k
SW1
=D1
LED1
LED3
PULSE
SLOW
y
R6
R1
t
D8
CMOS
.
D7
R16<
D5Z120
R13
22
R7
1.7k
R12
R8
7k
PROBE
TIP
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D2
T
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C3
14
1. 7 k
56k
C1
C4
13
1
10
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390k
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33k
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R15
120k
22
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01.
PULSEW2 MEMO
1pF
R20
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820k
tt
R18
5-15VDC
820k
1nF
R10
RS
D9
D6
C5
R9
47k
3
BC548
R17
820k=
22
R3
4
01
ti
120k
11
R14
120k
R19
2
LED
4
LEDS
O1.2k
O
C6'
01NF
T.,NF
o
DI
TO D9
010
1144148
,
:
1N4004
The circuit schematic for the probe. It will operate reliably in either TTL or CMOS circuitry, while the novel circuitry
associated with Ulc will either stretch or latch on pulses of either polarity.
ELECTRONICS Australia, August 1990
113
Logic Probe
mode; this allows C5 to continue charging as before, and finally the voltage at
pin 5 rises above that of pin 4 so that
Ulc can switch off.
If you've been wondering about the
function of Ql and its associated circuitry, this is basically a voltage regulator
circuit to supply the indicator LEDs
with a constant 3V DC, so that their
brightness is substantially constant despite the probe being powered from
supplies of anywhere between 5V and
TABLE 1:
CMOS & TTL LOGIC LEVELS
Family Maximum level Minimum level
for logic low
for logic Hi
CMOS 26.7% of Vcc 73.3% of Vcc
TTL
0.8V
2.0V
15V.
to its 'off state, with its output high
again.
As LED3 is also connected to the
output of Ulc, it illuminates during the
period that the comparator is switched
on. So the nett result of all this is that
Ulc acts as a monostable, which effectively 'stretches' the length of the input
pulse to make it visible via LED3.
The foregoing explanation assumed
that the. Pulse/Memo switch SW2 was
open, corresponding to the probe's
'PULSE' mode. The operation changes
when SW2 is closed, to set it for
MEMO (memory) operation.
When SW2 is closed, this does not effect operation before the arrival of an
input pulse, as the output of Ulc is
non -conducting and pin 2 is pulled high
by R18. However once a pulse arrives
and Ulc is triggered into conduction, its
output voltage falls and R20 holds pin 5
down to a level below the quiescent
level on pin 4 set by R16 and R14.
Hence even when CS has charged to
this intermediate voltage, Ulc remains
conducting and LED3 remains illuminated.
The circuit thus acts as a latch in this
mode, triggering with an input pulse
and remaining in this state. Once triggered it has to be reset manually, by
flicking SW2 briefly to the PULSE
LO
PULSE
HI
'
Ql is a standard emitter follower,
while LED4 and LED5 are being used
here as voltage reference diodes, supplied from the main positive rail via
R19. The reason for using two series connected LEDs instead of a 3.6V
zener diode is that this gives rather better regulation, at the relatively low current used here. Typical 3.6V zeners
have a somewhat higher dynamic resistance, and the resulting poorer regulation causes the LEDs to be quite dim
with a 5V supply, and over -bright with
a 15V supply.
Diode D10 is to protect the probe circuitry against reverse polarity connection of the supply leads. However as
D10 has a voltage drop of around 0.6V,
the top of the input reference voltage
divider R4/R5/R6-7 is connected directly
to the incoming positive lead, to ensure
correct operation with CMOS. This
doesn't place Ula at any risk of damage, however, as even when R7 is connected via SW1, there is still 33k of
series isolation between pin 9 of U1 and
the positive lead.
D1 and D2 are clamp diodes, to ensure that the probe input cannot take
the inputs of Ula and b more positive
than the positive supply rail, or more
negative than the negative rail. Resistor
R3 in turn protects the diodes from
damage.
LOGIC PROBE
-
Cat
MEMO
CMOS
PULSE
fi.
«4.5
DICK SMITH ELECTRONICS
L
So that's how the probe works. Elegant, isn't it? Now let's look at what's
involved in putting it together.
Construction
All of the probe circuitry and components are mounted on a small PC
board, measuring 132 x 22mm and
coded ZA-1447. As you can seé from
the photographs, the board fits snugly
inside a neat moulded probe casing,
whose external dimensions are 182 x 26
x 17mm (not including the probe tip.
The PCB is single sided, with all components mounted on the top. SW1 and
SW2 and miniature slider switches,
which attach to the board via small lugs
which are passed through holes in the
board and soldered on the copper side
in the same way as the actual contact
pins. LEDs 1, 2 and 3 mount directly
on the board, but spaced up so that like
the switches they protrude through
holes in the case 'front panel'.
The construction is quite straightforward, although care needs to be taken
during assembly due to the small and
PARTS LIST
Miscellaneous
Probe case and tip
Power lead with
spring mini clips
1
Pre -punched panel
insert
2 SPDT mini slider
switch
1
1
Resistors
All 1/4W:
3 22 ohms (R12,13,15)
1
1.2k (R19)
3 4.7k (R3,8,10)
1
33k (R4)
1
47k -(R7)
1
56k (R5)
5 120k (R6,14,16,18,20)
1
390k (R2)
4 820k (R1,9,11,17)
Capacitors
2
1
nF ceramic (C3,4)
3 0.1uF ceramic (C1,2,6)
1
1 uF 16V min. electro (C5)
Semiconductors
9 1N4148 diode (D1-9)
1
1N4004 (D10)
3 3mm red LED (LED2,4,5)
1
3mm green LED (LED1)
1
3mm yellow LED (LED3)
closer view of the probe, showing the display LEDs and the two slider
switches used to set the operating modes.
A
114
ELECTRONICS Australia, August 1990
1
1
BC548 transistor (01)
LM339 quad comparator (U1)
'
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Inside the case, showing how everything fits In.
compact nature of the probe. Note that
there are two short wire links underneath U1, which must be fitted before
the IC itself. There are three other
short links, one adjacent to Cl, one
next to SW2 and the other alongside
C5. There's also a longer insulated link
that runs from near SW1 to a point
alongside D10, and an insulated wire
that connects from the PCB to the
probe tip.
The four short links should all be fitted to the board before any components
are added, but the two longer wires
may be left until last.
The internal case height does not
allow the components to be mounted
too high off the PCB, so ensure that all
and
except the three display LEDs
are pushed down
the slider switches
against the board before they are soldered into place. This includes the two
'regulator' LEDs 4 and 5, and transistor
which should be pushed down as
01
far as it will go without putting undue
strain on its leads.
The height of the three display LEDs
is important, as if the leads are too long
the case will not fit together. Ideally
they should protrude slightly through
the cover so they can be easily seen, so
that the bottom of the bodies should be
-
-
-
about 6mm above the top of the PCB.
It may be best to leave these until last
before soldering them in place.
Apart from these points, assembling
the board should follow the usual
course. After the short links the resistors should be fitted first, followed by
the capacitors and diodes
taking care
to fit C5 and the diodes with the correct
orientation. Then you can fit the two
slider switches, 01, the two regulator
LEDs and the IC
taking care again
with orientation. Finally add the three
display LEDs, with the correct spacing;
a green one is used for LED1 (Lo), a
red one for LED2 (Hi), and a yellow
one for LED3 (Pulse).
Next you can fit the long insulated
wire link, and also the lead for the
probe tip. The latter should be cut to
about 70mm long overall, with 4mm of
insulation removed at each end for the
connections. The far end can be soldered to the rear of the tip, taking care
to make a good joint.
The final step is the connect up the
power supply cable, to the far end of
the board. Then you're ready to fit the
PCB assembly into the plastic case.
Note that on the inside of the top of
the case, near the centre, there are two
small spigots. The one closest to the
-
-
probe end will interfere with R1 or R3,
so cut this spigot off before trying to fit
the case together. The pre -punched insert for the 'front panel' can be
mounted before the case is finally fitted
and screwed together.
That's all there is to it. Providing
you've been careful in putting it together, your logic probe should work first
time without any problems. If it doesn't, the odds are that you will have fitted C5, one of the diodes, one of the
LEDs, 01 or UI with the incorrect polarity
so it pays to check these carefully while you're doing it, to save hassles later.
In operation, the only things to
remember are (a) to make sure that the
probe power connections are made to
the supply rails of the board you're
using it to check; and (b) to move SW I
to the correct position, according to the
type of logic circuitry you're checking.
The only other point to note is that
with SW2 in the 'Pulse' position, LED3
will indicate a 'stretched' version of
regardless of their polarity. In
pulses
the 'Memo' position it will stay on following a pulse, again of either polarity,
until you flick SW2 briefly back into the
'Pulse' position.
Happy troubleshooting!
-
-
And finally, here's the PCB overlay diagram, showing the location and orientation of all parts on the board itself. Don't
forget the two links under Ul, and the three other short links.
ELECTRONICS Australia, August 1990
115
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Rack Cabinet Sensation
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BUSHING STRIP
W
This is your chance to save a fortune on Deluxe Rack Cabinets.
here are, however, some minor faults with these units.
The 'Natural' units are supplied with silver alumanised front panels instead of
Similarly the 'Black' unit front panels are black powdercoat
the standard specification anodised.
The natural cabinets have
instead of Black anodised. Some top panel screw holes are misaligned.
black side/top and bottom panels.
Apart from these minor points, the cabinets are perfect and all units confirm to Intematinal Rack standards
Normal Price
Sale Price
Cat No
Description
This bushing strip is ideal for covering dangerous
edges of panel holes i.e. cut outs. Designed to
suit panel thickness of mm - 1.6mm. The strip
can easily be cut to length with a sharp knife or
scissors.
metre pack.
Cat HP -0730
1
1
,4.0 $1.95
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HB-5511
Natural 44mm
IR
HB-5513
Natural
HB-5515
Natural 132mm
H6-5510
Black 44mm
HB-5512
Black 88mm
HB-5512
Black 132mnu
Inc
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$65.00
$75.00
$90.00
$65.00
$85.00
$95.00
mm
39.95
49.95
59.00
39.95
49.95
59.00
35.00
45.00
55.00
35.00
45.00
55.00
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3.5 digit LCD display
Peak hold
Data hold
AC current 10mA to I000A
AC voltage 100mV lo 750V
voltage 1V to 1000V
Resistance 100M11 to 20kí2
Frequency counter 10Hz to 2kHz
Continuity check < 10012 with audio tone
Diode check
Multuneler leads suppplied
Unique one hand operation
Quality case supplied
DC
}g
Cat 0M-1570
ONLY $119.95
FAX - PHONE
PROTECTOR
,r
Thromatic
Security
Digital Clampmeter 100 AMP AC
Brand new model with more features for the same price Quality TES brand.
Features include:
This great product utilises a
passive infra red detector which
controls 240V lights to illuminate
at night when a person comes
within range. A typical example
would be on a verandah. Simply
replace the old light switch
(outside one) with the Thromatic.
When someone walkes within range (up to 15mt away) the verandah is lit up for them for
wl.
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-
a
period of 5 seconds to 10 minutes, or more.
Features:
Fully automatic compact design Security - keep intruders away On/Off/Auto
master switch on unit Safely - no more groping in the dark
Suitable for entrances, porches, patios, stairways, garages, basements, hallways, closets,
attics, storerooms, warehouses, workshops etc.
Up until now this type of product has been around 5100 or more. Jaycar has now directly
sourced this product, which effectively cuts out the middle man saving you money.
ONLY $69.50 SAVE $30 over previous
MODEM LINE
PLEASE READ THIS
models
Cat LA -5128
We are all becoming aware that lightning in storms can severly damage sensitive
electronic equipment connected to 'phone lines. Voltage spikes on phone lines are the
most common reason why FAX machines, answering machines. modems, cordless 'phones
etc , are damaged. Induced voltage spikes on telephone lines can be unbelievably high!
The best way to protect 'phone equipment during a storm Is to actually disconnect the
appliance from the wall socket. This is sometimes not possible of course.
The next best thing is to instal a device between the Telecom line and your expensive
equipment to protect the equipment from spikes. The big problem with such a filter is that
owing to the magnitude of the voltage spikes no practical filter could be ºuaranteed to
catch every soikg every time.
The Jaycar Telephone line Filter attenuates the enormous bulk of line spikes whilst
remaining effectively transparent to the audio band used by modems. FAX machines. etc.,
A number of Telecom grade spike attenuators are used including a quality German
Siemens gas arrester. The big factor in the efficiency of this filter, however, is earth
impedance. This filter must be connected to earth and the lower the impedance between
the unit and earth the better the filter works. The filter plug; into a Telecom socket and a
standard 240V mains socket (The mains earth is the only connection used).
We cannot guarantee that this filter will solve lightning induced telephone line spikes
destroying your equipment Some things (like the impedance of your earth system) are
totally beyond our control. We can say, however, that this device will give your equipment
a reasonable chance of survival in a storm.
We are so confident of this product that we are quite happy for you to use the unit for one
month without obligation. If you are not happy with this product in any way return the unit
in its original condition along with your receipt for a full refund.
Protect your expensive telephone, etc.. equipment from storm damage
Transparent to normal communications
instal in minutes
1. i
Uses no power
Cat XF1080
Panel Cutter
Revolutionises panel and sheet cutting. Ideal for making square/rectangular holes in plastic
panels and boxes for switches, LED displays etc.
Panel cutter is ideal for:
Plastic panels and sheets
Building materials made of urethane.
polyethylene, nylon, vinyl-chloride, Plywood, rubber sheets, leather, mat boards etc Soft thin
metallic sheets made of aluminium, lead, silver etc.
This is a quality tool make in Japan, which will last for years. Replacement blades will be
available. Actual tool length 120mm Supplied with three blades x 5mm and 2 x 10mm
diameter.
Cat TH-1940
1
$16.95
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I7iO
nq
Inc
111
Capacitance range:
2nf, 2Onf, 200nf, 2uf, 20uf, 200uí.:
Inductance range:
2mH, 20mH, 200mH, 2H, 20H.
A top quality unit and this month at a low low price
Don't miss out
Normally $189
T
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$99.00
1Single Core
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1110
Ito
NOW ONLY $139
Save An Amazing $50
Cat. 0M-1575
-
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VU
Hook-up Wire
Save a fortune over normal prices High qualtiy 1/0.4mm switchboard wire made in Australia
by Pirelli Cables. Cable is insulated with a two colour system, and many different colours are
Overall size 46(W) x 45(H)mm.
Meter Size 44(W) x 25jHpnm.
available. If ordering more than one roll please ask for different colours
jumper wires Supplied on metal reels 250mt length.
Yellow background with words
Ideal for breadboard
"REC LEVEL' on meter.
ONLY $4.95 - 250mt reel
FSD
Cat WH-3027
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Meter Bargain
As used in our 8002 mixer.
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400uA Coil 875 ohms.
DP-5058
WAS $9.95
NOW $4.95
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Philips Computer Capacitor
Bargain
1-t;110
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12A DC & AC current ranges
sR E
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Safety test leads
Zero ohms adjust
Mirrored meter dial
Tilt stand
Fuse protected
Working indicator
ds
E
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Normally about 525 ea
SAVE $10
RU -6714
NL
RE
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$79.95
NOW
RE
Passive Infra Red
Detector Sale
BARGAIN BAGS
24 dual element detection zones in three layers
Contains motor, brass cog, gearbox housing and all other
parts lo make various combinations of motor from 2rpm to
1150. Works from 1.5.4.5V DC. Depending on load
draws from
Contains approximately 3kg of assorted electronic goodies 'JUNK' if you like, but all brand new components etc. Ideal to
fill up your junk box.
Unfortunately due to the massive weight P&P is normal rates
plus 55
Cat. KB -9300
12 metre range
bargain at $30 each
Cat MM-2040
Due to huge weight mail order customers add 58 extra to
normal
P
&
P
charges.
A medium size transformer measuring 96 (1.)x 96 (W)
2x 120V50hz(240V)
x
1
$5.95
10-49 $5.50
50-99 $4.95
100 + $4.50
American, British, European
& Japanese transistors
listed with comprehensive
electrical. mechanical
specifications, lead
Cat No. MA 2618
connections diagrams,
manufacturers namesand
recommended substitutes.
Cat. BM -4554
Stock up now. Well under 1/2 normal price.
SIZE 1 505 x 205mm Cal HP -9522
$3.60
Normally $70 ea
Limited quantity available
i
Only $20 each
VARTA
SIZE
2 400 x 170mm
$ 2.40
$1.60
BATTERY MADNESS
VARIA 2.4 V 100mA/H Ni -CAD
ONLY x12.95
o
Cat HP -9523
SIZE 3 500 x 90mm Cal
Cal MM -2045
HP -9524
+
t.,.r.,c
av
***
...
10+ .900 each
100+ .750 each
\.Cal.
S8-2470
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These batteries are encased in a black plastic housing which measures 30 (L) x 16 (W) x 19 (H) mm. They were removed from
printed circuit boards by simply cutting of the PC terminals so to use you would need to break open the plastic case. Inside are
two 1.2 V cells. So purchase 4 of these, remove 1 cell and you have an 8.2 V (9V 216 type) battery for only S4. not about $20.
Ideal for Hobbyists, experimenters, etc.
I
To buy these today they would cost about S13 ea
BARGAIN LED PACK
ice
100 assorted LED's 5mm, 3mm, rectangular
plus others.
Normal value about 535
Cat. ZD-1696
ONLY $1 each
High Quality
Cat TH-1875
..
E.
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RE
AVAILABLE
Importers distress, your gain!
220mm long, yellow handles, super high quality. Normal trade
price is 535.04 including tax.
.
E'
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RE
RE
RE
NOW
PHENOLIC PC BOARD
RE
RE
RE
RE
RE
RE
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RE
RE
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Electricians Pliers Sale
x
P & P.
Towers' International
Transistor Selector
$39.95
80 (H)
16V 3A
extra
REW
1-9
Secondary 10 5V 3A
S4
RE
Over 27,000 (YES, TWENTY SEVEN THOUSAND)
R:
Primary
Mail orders add
E
Fi E
1F
(H)rnm
PF-4766
110 V
E
S INTERNATIONAL
TRANSISTOR SELECTOR
Simply insert your cables and crimp with a pair of pliers. Nylon
insulated casing. Pack of 8 pieces.
Cat HP -1210
1
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Cat LA -5017
EASY CRIMP WIRE
CONNECTOR
E
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$59.95
'TO
.R E
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¡.R E
SAVE $10
AUGUST
ONLY
Don't miss this one. Ideal for parts
220V 50hz primary I- no lead or plug supplied
- 16V AC at 800mA
Secondarys
- 9V AC at 1.5AMP
Lead length 1.7mt long terminated in a
strange plug
maxi
box style. Measures 75 (W) x 85 (L) x 60
Supplied in a
These transformers would normally cost about S80 each.
We have a limited quantity available for only 530 each.
A
15V DC
Normally
EXPERIMENTORS PLUG
PACK BARGAIN
Secondary
16 V Regulated to+12V DC 5A
16 V Regulated to -12 V DC SA
9.3V Regulated to 5 V DC 5.7A
RE
RE
FRE
Operation voltage 7.5
Tamper protected
LED indication
Relay output
$18.95
1x110V
RE
IR.RE
.
,
$69.95
A large transformer ideally suited to computer power
supplies. Size 115 (L) x 10 (W) x 86 (H) mm.
Primary
r
2x 120 V 50hz (240 V)
.RE
RE
TRF
Wide angle 90° multi layer coverage
full details.
Cat YG-2712
Ferguson Transformer
Bargains
PF-4725
E
RE
MOTOR/GEARBOX KIT
200-800mÁ
See catalogue for
E
Was $89.95
10+ 56 ea
1
R EL
Cat 0M-1050
ONLY $8.95
O
.R EL
Full electronic operation (FET)
15,000uF 40V Can
Cal
t
$1 ea
NOW
i
BACK IN STOCK
On - Pull
Multimeter
High input impedance
Polarity reverse witch
1
Swann brand. Orange knob which you push in for on, and pull
out for off.
I
Rated at 12 volt 16 amps.
'
Ct SP -0762
E
Features
Here's what you get 4 slotted bits 3 Phillips bits
9 hex bits
3 Robertson
bits
3 Posidrive bits
7 Torx bits
4 1/4' Star sockets
7 metric sockets
7
imperial sockets 1 x 1/4' drive socket adaptor
Ratchet
x 4' extension bar
driver.
And all this lot is housed in a tough durable metal case.
Cal TD -2002
(12 Volt Push
^,c,rrc
FET VOM
SCRWDRIVER SOCKET SET
$29.95
E
E
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ONLY $8.95
5mm 3000
MCD LED
An amazing 3000 MCD
of brightness in a LEDI
Lights up red, clear to
look at
ONLY
$3.95 10+
$3.65
Cal, ZD-1796
TURN YOUR
SURPLUS STOCK
INTO CASH!!
Jaycar will purchase your
surplus stocks of components
and equipment. We are
continually on the lookout for
sources of prime quality
merchandise.
CALL MARK
OR
gHAERRIS
ONROUTLEY
(02)
744
NOW
2022
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NOW ONLY .75¢ ea
By Ian Sinclair
CORE
This book covers the often neglected topic of electronics power
supplies. All types of supplies that are used for electronics
purposes are covered in detail, starting with cells and batteries
and extending by way of rectified supplies and linear stabilisers
to modem switch -mode systems. IC switch -mode regulators,
DC -DC converters and inverters.
The devices, their operating principles and typical circuits are all
dealt with in detail. The action of rectifiers and the reservoir
capacitation is emphasised, and the subject of stabilisation is
covered. The book includes some useful formulae for assessing
the likely hum level of a conventional rectifier reservoir supply.
Covers many types of supplies - batteries, simple AC supplies,
Two telescopic antenna mounted in a
sturdy cabinet which sits on your TV set
Telescopic rods are adjustable for
maximum efficiency.
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Plugs
Cat
10+ .80c
10+ $4.50
SAVE $2
NEW 20 way
Stock Up Now
PC Pin
Cat,
PI
-6413$3.00
NOW ONLY
Specifications
Darlington Vceo 30V Ic 1000mA
Plot 800mW ' 25°C ' HFE > 2000
Toff 1500ns 500mA Ic
ELFrRVInGS
These units will not work as a PH & chlorine meter and are
being sold as parts only (unless you can fix them). Parts
include a panel meter, a transistor radio on/off switch, pot/
volume control with knob, a length of 2 core quality cable
with a 60mm curly cord section, a 1.5V battery holer is built
into the case, and a 1.5V battery is supplied. The meter
alone is worth $10. These units were originally being sold
for $39.95
500mA
Cat n-2216
'AC
250
ea
ONLY $3.95
Millivolt Meter Sale
Cat. QM -6135
11*4gfli*".
1?
$200
,;1110
Save
$25
1.:1140
Cat
RRO
OT -2320
BÓÓK
Mike Tooley BA
12V DC Fan
At
last Jaycar now stocks
an
BOrnm square 12V DC fan
Quality Japanese brushless style.
Limited quantities.
tTTFn1ó
IRO
.1RO
HP -1252
Ph & Chlorine Meter
NOW
IRO
3
Cat
$11.95
1
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:IRO
pins Pk 500 pcs.
Less than 2.54 per pin Stock up Now
Philips BSR52 Darlington
Transistor Bargain
Was
$225
'Ctno
PC
Normally $15.95
Measures AC volts from 0.3mV to 100 V and 5Hz to mHz.
See Catalogue for full specs.
TRO
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:TF10
Bargain
Standard 0.9mm
rack to suit
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TITO
TRo
-6549
Normally $6.95
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110
PI
Normally $1.95
NOW ONLY $1 ea
10 for $1.50
ñ''`1
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'CIRO
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14 Way Insulation
Displacement Type Header
$3.95
IC
ONLY
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ONLY $5.95 pk
5.5' long
$4.95
$19.95
NVáget
80n/o at our normal price of 58.95
Cat RZ-6695
Socket Strips Basically the same as the machine pin
variety but they have wire wrap pins. 32 way.
Cat PI -6472
Mellow
BP-1218
S5 each. Values range from .33uF up to 47uF.
$9.95
Wire Wrap Machine Pin
116 pages, size 135 x 215mm.
CTnc
NOW ONLY
AUGUST
Practical details on equipment wiring, acoustics and sound
proofing.
Glossary of terms and lists of useful addresses.
c Inc
Normally $19.95
Normally $6.95
For musicians, recording enthusiasts and students.
'CTRO
CTRO
Tantalum Pack
NOW ONLY
wiring schemes and describes how to custom build
your own particular requirements.
'C I RO
for $1
Tantalums are getting more expensive all the time. Due to a
very large bulk purchase. we can offer you a mixed pack of
over 50 Tantalums. Over 40 of these are tag type and the
rest high quality military spec RT type which are worth up to
Pk 100 Red
The book describes the setting up of an 8 to 16 track studio with
an outline of the musical and recording gear needed, but
concentrating on the techniques of putting that equipment
together into an efficient and productive home studio.
It contains irrvalable and hard to come by advice on patchbay
CTEtc
,C IRO
m/"
Cat. WW -4336
cording Studio
CntC
CInC
CIRC
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SAVE OVER
How To Set Up A Home Re-
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Cal RE -5897
Wire Wrap Wire
$19.95
BP -1220
NOW
Cat. 1T-3110
switch -mode supplies and inverters.
Includes stabilisation and regulators.
Explains operating principles and gives typical circuits.
For technicians, students and enthusiasts.
136 pages, size 135(W) x 2159H)mm
CIRC
'CHIC
1.II -Yea
Normally $1 each
CORE
CTR<
°.z
220uF 63V VRT electro
Rabbit Ears Antenna
Below 1/2 Price
Handbook
AC -1684
Capacitor Bargain
Save .70e
Electronic Power Supply
C ORE
rECTRI
Cal
;r
.
4,
10+ S2
1/1111111.1.00.
TV
LC IRE
$2.50
NO'.:' ONLY
Normally $1.45 each
$19.95
BP -1222
Catalogue price $7.95
Size 32mm diameters o 17mm high.
Cal HK -7756
standard' components and devices.
A must for everyone involved in electronics.
250 pages 140 x 215mm
E
-
We've overstocked.
High quality black plastic knob with
aluminium insert. Standard 1/4' shaft
book with numerous examples showing how theory can be put
into practice using a range of commonly available 'industry
1ECTR
CIA
CM,
Knob Special
It is ideal for the hobbyist, student, technician and engineer. The
information is presented in the form of a basic electronic recipe
FCTN
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Cat. RU -6730
electronic applications.
CIR
If
ECTR
CTR
101$2.00 each
relevance in the world of electronics. It contains not only
sections which deal with the essential theory of electronic
circuits, but it also deals with a wide range of practical
ECTF
CTF
ECTR
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ONLY $2.50 ea
Mike holey
ref
Vertical format Power handling 15.20 watts. About 80
watts system power. The potentiometers can be removed
which makes them ideal replacements for blown ones.
Grab em while you can. This won't be repeated. Size
40mm high 30mm diameter.
This book is an invaluable source of information of everyday
EMT
Midrange and Tweeter
Level Control
3300 OF 63V RB ELECTROLYTIC
BARGAIN
Book
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BOOKS FOR 1990
Everyday Electronics Data
SA.
Cat YX-2512
$24.95
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SINE/SQUARE WAVE GENERATOR
R I L
This new Digital Sine/Square Wave Generator uses high speed CMOS and a digital filter IC to produce sine and square waves
over a very wide frequency range - from 0.1Hz to 500kHz
Specifications:
Frequency Range: 0.1Hz to 500kHz in four ranges - 0.1Hz to 10Hz, 10Hz to 1000Hz.1kHz to 100kHz and 100kHz to 500kHz.
Output Waveforms: Sine and Square
Harmonic Distortion: Less than 0.1% from 0 1Hz to 50kHz, 0.27% at 80kHz
Square
Wave Rise Time:lOns Square Wave
Fail Time: iOns
Output Level: Sine wave
variable from 0-1.2Vrms; Square wave
variable from 0 to 5V p -p Output
Impedance: 600 ohm nominal
Load
Impedance 600 ohm to infinity Protection:
Short circuit protected (indefinite) Display
_
Accuracy: (pm) 2% (ps) digit
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The Jaycar kit includes PCB, box, punched
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and screen front panel and all specified
components.
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Power Supply Load Protection Kit
Refer Silicon Chip June 90
This add-on board prevents dangerous voltages from
being delivered to a load by any dual trackng power
supply when it is turned on or off.
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KC -5076
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Ideal for a magnetic cartridge, tape player or
microphones. Shortform kit, includes PCB switch.
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cable and all electronic components.
No box front panel or panel hardware supplied.
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KC-5077
$32.95
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Capacitance Meter Kit
Low Noise Universal Pre Amp Kit
Cat
1411
Kit includes PCB, mic insert and all specified components.
CaL KC -5080
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$229
Cat No. KC -5073
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Kit includes PC8, die cast box and all
components to finish the kit
EL
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This kit features high efficiency toroid power transformer, professional high resolution 10 turn wire wound voltage control potentiometer, latest I.C. technology, excellent line load
regulation, low ripple voltage, apart from a smart plastic case! (for more information see
specs below).
The Jaycar kit is complete down to the last nut and screw as well as all hard-to -get I.C. s.
and all electronic components supplied (excluding optional receiver parts). No box or box
hardware supplied.
Refer silicon Chip May 90
Designed for cars with Reluctor distributors,
this ignition kit features improved protection
for the coil and main switching transistor.
EL
it
is a great project that is fun to use once you've built
hone can sit anywhere and when he hears a sound he will chirp
back. lions is small and can easily be hidden.
Ref: Silicon Chip April
Replace those expensive 9V batteries with an economical 1.5V D cell. Lasts much longer and
saves you the cost of the kit in no time. Shortform kit - PCB. potcores, battery holder, heatsink
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Ref: EA May 1990
$19.95
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FOR ALL THE
Ref: Silicon Chip August 1990
Refer Silicon Chip May 90
This attractive 4 digit capacitance meter
kit is designed for workshop. laboratory or
serious hobbyists. It can measure
capacitance from pf up to 9999uí in
seven ranges with an accuracy of better
than
1%a/- 1 digit. Kit is complete
with all components required to
finish construction.
KC -5075
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MAIL ORDERS
SYDNEY
VISA
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CITY
115 Parramatta Road Concord 2137
Telephone (02) 747 2022
FACSIMILE (02) 744 0767
MAIL ORDER VIA
3.75
4.50 ROAD FREIGHT
510 - 524.99
S
S25 - S49.99
S
550.599.99
S650
OVER $100
S8.00
+R C
Mon -Fri 8.30 -5.30 Thurs 8.30 pm - Sat 9
- 12
PARR AMATTA
355 Church St (Cnr. Victoria Rd) (02) 683 3377
Mon -Fri 9 -5.30 Thurs 830 pm - Sat 9. 4pm
CONCORD
115 Parramatta Rd (02) 745 3077 Mon -Fri 8.30.5 30 - Sal 830 - 12
HURSTVILLE
121
Forest Rd (02) 570 7000 Mon -Fn 9.5.30 Thurs 8.30 pm
-
Sat
9.4
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IN AUSTRALIA (up to 20kpl
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51350
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GORE HILL
188 Pacific Hwy (Cnr. Bellevue Ave) (02) 439 4799- Mon-Fri 9.5.30 Sat 9.4pm
-R El
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BURANDA QLD
144 Logan Rd (07) 393 0777 Mon -Fri 9 - 530 Thurs 830 - Sat 9
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TOLLFREE (008) 022 888
117 York SL (021267 1614 -
JAI CAR ELECTRONICSJAYCAR EL ECTRONICSJAYCAR ELECIRONICSJAYCAR ELECTRONICSJAYCAR
JAYCAR ELECTIIONICSJAYCAR ELECTRONICSJAYCAR ELECIRONICSJAYCAR ELECIRONICSJAYCAR
:S JAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR LLECTRONICSJAYCM ELECTRONICSJAYCAR
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POST 8 PACKING
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Concord 2137
HOTLINE (02) 747 1888
FOR ORDERS ONLY
HEAD OFFICE
ELECTRONICS
LOLCkl+d)
POBBox 1B5
12
MELBOURNE -CITY
Shop 2, 45 A'Beckett SI City (03) 663 2030
Mon -Fri 9 - 5 30 Fri 8.30 - Sat 9 - 12
SPRINGVALE VIC
887-889 Springvale Road Mulgrave (03) 547 1022
Nr Cnr. Dandenong Road Mon -Fri 9 - 5.30 Fri 8.30
ADELAIDE S.A.
190 Wright Street (Cnr Selby Street) (08) 231 7355
Mon -Fri 9.530 Fri 8.30 - Sat 9. 12
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ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR El
ELECTRONICSJAYCAR ELECTRONICSJAYCAR ELECTRONICS JAYCAR ELF CTRONICS JAYCAR E L
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Construction Project:
Improved Prograrnm1II
Combination Lock -
What! Not another keypad entry combination lock you say! No
this one has numerous
features over others published before. In particular it stores the entry code in a memory,
allowing the code to be changed. The unit can also be used to trigger or even arm or disarm
an existing security alarm. It's cheap, easy to build and the onboard relay can control loads of
up to 10A.
by JEFF MONEGAL and PETER PHILLIPS
rage door or gate, that could use an
extra means of control.
Its main purpose is to act as an electronic `key', and the applications are
numerous
including, of course, use
with a conventional door lock solenoid
via the onboard relay.
As shown in the lead picture, the unit
comprises a keypad connected with ribbon cable to a box containing the electronics. The key pad would usually be
fitted at a point convenient to the door,
being protected from the weather, while
the electronics is placed somewhere out
of harm's way. For added security, you
could even include two extra wires in
the ribbon cable, connected as a loop to
your alarm system. This way, if someone cuts the cable in an attempt to
break in, the alarm will be triggered.
-
s
9
1
2
3
4
5
7
6
6
9
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- ±a
How it works
I_
Protect your home or car with this programmable combination lock. The unit
allows you to change the entry code, and it can interface to an alarm system
as well.
Digital combination locks offer several advantages over conventional locks
and keys. You can't lose them, you
can't steal them, they can't be picked
and, in our version, the entry code can
be easily changed. The only disadvantage is that you must remember a numeric code. And in the age of the PIN
number, this is something most people
have become accustomed to.
With our new programmable combination lock, you program it with a four digit code to open the lock and another
four -digit code is used to put the lock
into program mode. When in program
mode eight digits are entered in all, of
which the first four digits make up the
new 'open lock' code and the last four
become the new 'enter program mode'
120
code. What could be simpler?
In case of power failure, a backup
battery is available to power the circuit,
and as the recommended battery is a
1.2Ah rechargeable type, enough power
is available to operate a door lock solenoid as well. In normal operation the
internal battery is trickle charged by the
onboard charging circuit, keeping the
battery ready for emergencies.
The lock can also be used in a house
(or a car) to arm or disarm a security
system. For example, the lock can be
wired to not only open the front door,
but to also disarm the burglar alarm system on entry, taking the worry out of
false alarms if you aren't quick enough
with your manual disarming.
Or perhaps you have a motorised ga-
ELECTRONICS Australia, August 1990
The circuit looks rather complicated,
but is easy enough when broken into
sections. There are two modes of operation; `program' mode and `operate'
mode. We'll describe the program mode
first, as programming the unit is required before it can do anything.
When power is first applied, two
power -on reset circuits put the circuit
into program mode. Power -on reset will
only occur when the unit is first turned
on, or if the power has been off for a
few days and the back-up battery has
gone flat, requiring power to be restored to the circuit. Under these conditions, a positive (logic 1) reset pulse is
applied to pin 1 of the address counter
IC5 and also to pin 15 of the 'correct
key' counter IC7, as a result of C6
charging through R9. Once C6 has
charged, R9 will hold the reset pins of
both IC5 and IC7 low.
The second reset circuit is that pro -
r
vided by C7 charging through R20. This
circuit applies a logic 1 to pin 8 of IC8c,
causing output pin 10 of the flipflop
comprising IC8c and IC8d to be reset to
a logic O. The other output (pin 11 of
IC8d) will be set to a high. The logic 0
at pin 10 puts IC4, the 2114 memory
IC, into write mode (logic low level at
pin 10 of IC4) and enables the tri-state
buffers of IC3 (IC3a to 1C3d).
IC4 is a 1024 x 4 bit static RAM, in
which only 'the first 16 addresses are
used, as selected by address pins 4 to 7.
Pin 11 of the flipflop (IC8d) will disable
both the `wrong key' counter IC6 and
the 'correct key' counter, IC7 by placing
a high at pin 13 of both ICs. The unit is
now in program mode.
ICI is a two -of -eight keyboard to binary encoder. When any key of the keypad is pressed, the equivalent binary
code for that key will appear at output
pins 10 to 13. Pin 10 is the least significant bit (LSB) of the code. This code is
placed on the input/output lines of the
memory IC, (IC4, pins 11 to 14) via the
tri-state buffers of IC3, and is stored in
the memory, as the memory is in write
mode.
After 80 clock cycles following the
last key press, (debouncing period) a
positive output pulse occurs at pin 14 of
IC1. This pulse clocks the address
counter IC5, to the next memory address location. When another key is
pressed the whole process is repeated.
After eight key presses, the cycle needs
to be ended by pressing either of the
system reset keys, marked `#' and 'e'.
When either of these keys is pressed,
diodes D1 and D2 will be reverse
biased, causing a high at the inputs of
AND gate IC9c via pullup resistor R18.
This gate is a buffer and will therefore
output a logic 1 at pin 3. This resets the
address counter IC5 back to 0000, and
causes pin 4 of the flipflop comprising
IC10c and IC10d to be set to a logic 1.
This output can be used to arm an existing alarm system if required, and the
'Arm' indicator LED gives a visual indication of the status of this output. The
'Arm' condition can only be reset by
entering the `unlock' code.
The high at pin 3 of IC9c also resets
the program mode flipflop of IC8c and
IC8d, in which pin 10 of IC8c goes
high, enabling the `wrong key' and the
`correct key' counters (IC6 and IC7 respectively). The tri-state buffers of IC3
are also disabled by the high at pin 10
of IC8c, by returning them to their high
impedance mode. It also sets the
memory IC4 to read mode, as the R/Wbar input (pin 10) will now be a high.
The circuit is now in `operate mode',
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circuit for the combination lock uses a static RAM to hold the codes. The
keypad connects via seven lines to IC1, which outputs the binary code foi
each key.
The
ELECTRONICS Australia, August 1990
121
Combination Lock
applied to input pin 12 of AND gate
IC9a from either pin 12 or 13 of IC2,
the output of this gate (pin 11, IC9a)
will be a logic 0. As a result, the 'correct key' counter IC7 will be incremented by one count. The same thing
will happen as long as the next three
key presses are the numerals 2, 3 and 4.
If an incorrect number is entered,
word A will be different to word B, and
IC2 will output a logic 1 at either pin 12
or pin 13, depending on whether word
A is less than or greater than word B.
This will clock the 'wrong key' counter,
IC6, as under these conditions, pin 11
of IC9 will go high when the strobe output (pin 14) of IC1 goes high. The logic
1 from IC9a (pin 11) will also reset (to
0000) the address counter (IC5) and the
'correct key' counter (IC7) via diode
D8. Thus, if an incorrect key is pressed,
the user has to start all over again.
However, after three false tries, output pin 7 of the 'wrong key' counter
(IC6) will go high, setting pin 3 of IC8b
to a logic 1, turning on Q7 and lighting
the 'alarm' LED. The collector of 07
will fall to zero volts under these conditions, and this negative transition can be
used to trigger an alarm system if reis
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The layout diagram for the combination lock. Although the PCB is double
sided, this diagram only shows the tracks on the underside. Tracks between
sides are joined by component leads, excepting the point shown, which
requires a link through the board. Note that 1C2 faces the opposite way to the
other ICs.
with address 0000 of the memory IC selected. The data in this address will be
the binary equivalent of the first key
pressed during program mode, and the
next seven addresses will have a binary
value equal to whatever key sequence
was pressed while the unit was in program mode. Thus the circuit is now
waiting for the first key of the keypad
to be pressed.
Let's assume that a code of 1-2-3-45-6-7-8 was entered during program
mode. Thus address 0000 of the
memory will contain binary 0001, and
pin 14 of IC4 (LSB output of the
memory) will be high. The outputs of
the memory are connected to IC2,
which is a four hit magnitude comparator. This IC compares two 4 -bit words
and has three outputs; both words equal
(pin 3), word A less than word B (pin
13) and word A greater than word B
(pin 12). Word A comes from the keyboard encoder ICI and word B is supplied by the memory. Because word A
is currently (XXX) (no key press) and
word B is (1001. pin 13 of 1C2 will he
high.
If the numeral key ' I' on the key pad
is pressed. words A and B will he
equal. causing the 'equals' output of
122
IC2 (pin 3) to go high. After the 80
clock cycle debouncing period, pin 14 of
IC1 will go high. This pin is connected
to AND gates IC9a (pin 13) and IC9b
(pin 9), resulting in a logic 1 at the output of IC9b (pin 10). Because a logic 0
quired.
The only way to turn off the 'alarm'
LED is to enter the correct four -digit
code, and no warning is given prior to
the third attempt, giving excellent security.
If on the other hand the correct fourdigit code is entered, pin 10 of the 'correct key' counter, IC7 will go high. This
does a number of things. First, the
'wrong key' counter IC6, is reset by the
logic 1 at its reset input (pin 15). Also,
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The keypad and LEDs connect to the main PCB with a 13 -wire ribbon cable,
as shown in this photo. Use silicone glue to fix the LEDs and the keypad to
the box, which needs a rectangular cutout for the keypad.
ELECTRONICS Australia. August 1990
Q8 will be turned on, operating the
'open' LED and the relay, which drives
the door lock solenoid.
Timing capacitor C8 is also connected
to pin 10 of IC7, and it will charge via
R10. When the voltage across this capacitor has charged sufficiently (after
around two seconds), the level at pin 13
of IClld will equal a logic 1, causing a
logic 1 to appear at the reset pin (pin
15) of IC7. This will reset the counter,
turn off Q8, the 'open' LED, the relay
and the door lock solenoid, and the circuit re-enters its normal operating mode
awaiting the next input code.
If you wish to go into program mode,
then the fifth key press must occur before the two second timer has finished.
After the remaining three digits of the
entire eight digit code have been entered, pin 9 of IC7 will go high, sending
pin 8 of IClle high. This will set pin 10
of IC8c to a low, and the unit is now in
program mode as previously described.
As before, if a wrong key is pressed
during the 'program code' the entire
eight digit code must be re-entered. If
three wrong keys occur in the program
code, (digits 5 to 8), the alarm condition will occur.
The clock signal for IC1 (pin 15) is
provided by the oscillator formed by
IChia, R12 and Cl. The keyboard uses
a standard three -by -four matrix to code
each key, and transistors Ql to Q4 are
required to interface the keyboard to
ICI.
To give visual feedback of a key
press, the output pulse at pin 14 from
the keyboard encoder IC1 is fed to a
timer comprising IC10a, IC10b, R15
and C5. As already described, a positive
pulse occurs at pin 14 of ICI after 80
clock cycles, and this pulse is used to
trigger the timer, which effectively
stretches the pulse, lighting the 'key
pressed' LED via transistor 05.
Power to the circuit is either from an
external 12V supply or, in the event of
power failure, from the 12V backup
battery. Diode D4 isolates the incoming
mains derived DC supply from the
backup battery when the mains fails.
The network comprising C2, C10, R13
and ZD1 provide suppression of any
noise on the DC input, and IC12 regulates the 12V input down to the required 5V. Noise suppression on the 5V
rail is provided by C3 and C4. The
backup battery is charged via R14, and
D3 allows the battery to power the circuit when the mains fails. The recommended battery will last in excess of 24
hours under normal conditions.
Construction
A kit of parts for this project is avail-
from CTOAN Electronics for
(See details at end of this
article).
The PCB is double -sided, and some
of the tracks are connected between
sides with component leads, including
the leads of some of the ICs. For this
reason, IC sockets are difficult to fit,
able
$59.50.
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The artwork for both sides of the PCB is reproduced
full size for those who wish to make their own.
ELECTRONICS Australia, August 1990
123
Combination Lock
unless wirewrap or similar types that
allow soldering on both sides of the
PCB are used. Alternatively, Molex IC
socket strips could be fitted. You will
need a soldering iron with a fine tip,
and if you solder the ICs directly to the
PCB (as in the prototype), earth the tip
of the iron, as most of the ICs are
CMOS types. (By the way, CTOAN
will construct the unit for you if required details at end of article).
The first task is to inspect the PCB.
Because some of the tracks pass between IC pins, examine the PCB under
a magnifying glass, just to be sure there
are no manufacturing problems
particularly with shorted tracks. Spend
some time with this, as any problems
found now will save considerable time
later on.
Commence construction by fitting the
resistors and capacitors. Where a component lead passes through a track on
both sides, make sure the lead is soldered to both tracks to ensure the
-
-
tracks are joined. Check that the polarity of all electrolytic capacitors is correct before soldering them in place.
Next fit and solder the diodes. Check
carefully that all diodes are correctly
orientated, and again check that you
solder on both sides of the PCB if
tracks are being joined by a diode lead.
The eight transistors can now be fitted
to the PCB. All transistors are the same
type, and none require soldering to
both sides of the PCB. The relay can
also be soldered in place, leaving only
the ICs and the ribbon cable to go.
As already said, the usual type of IC
sockets cannot be used because of the
solder joins required on the component
side of the board. If you elect to use a
type that will permit soldering top and
bottom, then these can now be fitted
and soldered. Otherwise, insert each IC
in turn, and solder (on the underside of
the PCB) only those pins that are used.
Then inspect the component side of the
board and solder those pins that connect to a track on this side.
Prior to inserting the IC, it may useful
PARTS LIST
Resistors
unless noted
R1,9,12,15,18,20
All 5%, 1/4W
100k
R2,4,7,16,21
4.7k
R3,5,6,17,22
470 ohms
D1,2,5-13
1N4148 signal diode
D3,4,14 1N4001 1A diode
ZD1
15V 1W zener diode
LED1-5 3mm LEDS (green, red,
orange)
Miscellaneóus
R8,10,11,19
1
1M
1
R13,14
10 ohms 1W
1
Capacitors
Cl
3.3nF ceramic
100uF 16V electro
C2,4
C3
680pF
C5,10 1uF 50V electro
C6,7,9 0.1 uF monolithic
4.7uF 35V, electro
C8
Semiconductors
MC14419 keyboard
encoder (Motorola)
4585 4 bit comparator
4503 three state buffer
2114-3 1K x 4 static
101
IC2
IC3
IC4
RAM
IC5
IC6,7
IC8,10
IC9
IC11
10 12
01-9
124
4029 counter
4017 decade counter
4001 quad NOR gate
4081 quad AND gate
74C14 hex Schmitt
Inverter
7805 voltage regulator
BC548 NPN small signal
1
1
1
1
1
12V miniature relay
PCB,double sided
128 x 75mm coded CE90
PDL
12 key numeric keypad
1.2Ah rechargeable battery
12V/1 A DC plug pack
200mm by 13 way ribbon
cable
Jiffy box, 28 x 54 x 83mm
Jiffy box, 50 x 90 x 150mm
A kit of parts for this project is
available from CTOAN Electronics.
Cost of the kit is $59.50 (plus $2.50
post and pack) which includes a
double sided PCB, all components
and the key pad. A limited number
of gel batteries are available for
$19.95 (plus $2.00 post and pack).
Fully built and tested units are available for $99.90. This price does not
include the back-up battery or the
cases. To order, write to or phone:
CTOA N Electronics
PO Box 33
CondeII Park. NSW 22(X)
Phone (02) 7083763
ELECTRONICS Australia Auoust 1990
to mark the points that need soldering
on the component side of the PCB, as
some tracks pass under the IC, making
it difficult to see which pins need soldering on the component side. Do the
soldering fairly quickly, to prevent overheating the IC. Because most of the ICs
are CMOS, the soldering iron tip should
be earthed to prevent static discharge
damaging the IC. Note that IC2 (4585
comparator) faces the opposite way to
the other ICs. The voltage regulator
IC12 has one connection soldered both
sides (the 5V output terminal).
It remains to connect the ribbon
cable, the power leads and (if required)
a link to power the relay. As shown on
the circuit diagram, the common contact
of the relay is connected to the supply
for the relay coil, allowing the load connected to the relay to be driven by this
supply. For this reason the relay can be
powered from either an external 12V
DC supply, or from the 12V DC input
powering the PCB. If you choose to
power the relay from the PCB's 12V
DC supply, fit a link as shown on the
layout diagram. This link can be fitted
on the bottom side of the PCB (as in
the prototype), although pads are provided to fit the link on the component
side.
The ribbon cable connecting the PCB
to the box holding the keypad and the
LEDs requires 13 wires. Of these, seven
connect to the keypad, five connect to
the cathodes of each of the LEDs, and
the remaining wire supplies +5V to the
anodes of the LEDs. Using the layout
diagram as a guide, connect the ribbon
cable to the PCB. We used a cable
length of around 200mm, although this
will vary, depending on the application.
Now arrange the LEDs and keypad
on the workbench, so they are in the
approximate position they will occupy
when fitted to the case. Alternatively,
these can be fitted to the case first, (as
described further on), although soldering the leads may be more tricky. In
any case, trim the ribbon cable so that
each wire is approximately correct in
length and solder each wire in the cable
to its required LED (cathode) or point
on the keypad. A common +5V wire is
required to supply each LED as well.
We used a length of tinned copper wire,
supported by the anode leads of each
LED.
Finally, connect the power input leads
and the leads to the backup battery.
Also, a lead from the relay contact to
the door lock solenoid (if used) can he
fitted. The negative supply to the solenoid can he connected to the same
print
the I'_\, negative input to the
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This photo shows the main PCB of the prototype. The PCB track patterns are now slightly different to the prototype,
but the component layout has changed only slightly. The link to power the relay was fitted to the underside of the PCB.
PCB. Once all wiring and soldering is
completed, carefully check everything
for errors.
Testing
To test the unit, connect a 12V DC
supply to the PCB and switch on the
power. The current consumption should
be around 80mA or so, and the 'Arm'
and 'Program' LEDs should both light.
If not, try disconnecting then reconnecting the power, to get a power -on reset
condition. Pressing any number key on
the keypad should cause the 'key' LED
to briefly light. If none of the above
occur, make sure that the regulator is
supplying 5V to the circuit. Correct if
necessary.
Otherwise, faultfinding will require
the use of a logic probe connected to
the 5V rail and ground. Check that
there is a clock signal at pin 15 of ICI,
and that pin 14 of this IC gives a pulse
output after each key press. If so, go
through the circuit with the logic probe,
looking for logic errors. Typical problems will include IC pins not soldered
(check those on the component side of
the board in particular), ICs or diodes
around the wrong way, and so forth.
We constructed several versions, and all
worked without any problems.
If everything seems to be working so
far, reset the circuit by momentarily disconnecting the power. Then enter any
eight digit code, followed by a press on
either the '#' or '*' keys. The 'open'
LED should light for a few seconds if
the first four digits of the code are entered after the unit has been programmed. Also, the 'Arm' LED should
extinguish. If neither of these LEDs
I
react as described, try pressing the '#'
or '*' keys prior to entering the code. If
it still doesn't perform, get busy with
the logic probe.
For example, confirm that the outputs
(pins 10 to 13) of ICI are all low when
no key is pressed, and that they respond
by giving the binary code for each press
of a number key. After a power -on
Y'
A
These door lock solenoids operate at 12V and replace the section fitted in the
architrave around the doorway. When the internal relay is energised, the door
can be pushed open; normal operation with a door key is not affected. Those
shown are courtesy of Oatley Electronics, and range in price from around $60
to $80.
ELECTRONICS Australia. August 1990
125
Combination Lock
with four screws and nuts. There are
four mounting holes provided in the
PCB, and a box measuring 50 x 90 x
150mm (size UB1 from Dick Smith
Electronics) was used. File a relief slot
between the lid and the case as an exit
point for the ribbon cable and the
power leads.
The keypad and indicator LEDs all fit
nicely into a 28 x 54 x 83mm jiffy box
(UB5). Cut a rectangular section out of
the bottom of the box to allow the keypad to be fitted. We used silicone glue
(Silastic or similar) to hold the keypad
and the LEDs in place. This also serves
to waterproof the box.
Drill 3mm holes for the LEDs, arranged around the keypad as shown in
the photographs. Use white rub -on lettering to label each LED, and apply
plastic lacquer over the lettering to protect it. Don't apply the lacquer with the
keypad in place, as it may affect the
operation of the keys. Again, file a relief slot to accommodate the ribbon
cable before fitting the lid to the box.
The rest is now up to you. The parts
list suggests a 12V/1A DC plug pack as
the external power source. The current
consumption of any load driven by the
relay that is powered by this source
should be included in the total load cur-
reset, the address pins 4 to 7 of the
memory IC (IC4) should all be low and
should increment by one after a key
press. The three outputs of the comparator should function as described in the
'how it works' section.
In short, study the description of the
circuit operation, and use a logic probe
to confirm each section of the circuit. If
all else fails, then CTOAN Electronics
will fix it for you as long as the construction is neat and complete. The cost
is $25.00 maximum plus $2.50 post and
pack.
When the unit is operating correctly,
you should be able to enter an eight digit code after a power -on reset, open
the lock with the first four digits, and
re-enter program mode by entering the
remaining four digits before the 'open'
LED goes out. Don't forget to press the
'#' or '*' after entering the complete
eight -digit code.
Final assembly
In the prototype version, the PCB
containing the electronics for the lock
was mounted inside a jiffy box, by attaching the PCB to the lid of the box
SCIENTIFIC
TEKTRONIX
PHILIPS
WAVERTEK
SIMPSON
FLUKE
rent, to ensure the plug pack is suitably
rated. A 12V gel -type backup battery
can be attached and tested, to ensure it
not only powers the circuit when the
mains is switched off, but that it is
being charged by the circuit.
If you intend using the lock to trigger
a burglar alarm, run wires from either
point A or point B of the PCB as
shown on the layout. Point A swings
from +12V to ground when the lock is
'opened'. If you use this output to trigger the alarm, make sure the alarm
module is compatible with a 12V trigger
signal. Point B goes from a logic 1
(+5V) to ground (negative -going transition) when the alarm condition of the
lock occurs.
To arm or disarm an alarm system
with the lock, use outputs X or Y. Point
X goes to a logic 1 and point Y to a
logic 0 when the 'Arm' LED of the lock
is on. Note that these outputs are
CMOS, at 5V. Pressing either the '*' or
'#' keys will cause the 'Arm' LED to
light, which can only be cancelled by
entering the correct four digit code.
All that remains is to fit the unit to a
door, an alarm, a gate or anywhere requiring an electronic 'key', and you're
in business. Just don't forget the code
you only get three chances!
-
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HEWLETT PACKARD
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READER INFO NO. 29
API INSTRUMENTS
ELECTRIC
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CH1 signal output allows direct connection to a frequency counter
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ll1:; 1171111/111115 IN All
READER INFO NO. 30
Construction Project:
S$TV Transmit
3canconverter - 2
Having described the circuit operation, our author continues this month with the construction,
testing, alignment and use of his converter. He also discusses component supply choices. Most
of the circuitry is mounted on two PC boards, to make assembly straightforward.
by LEON WILLIAMS, VK2DOB
to be bent slightly outward so that the
body can be screwed to the rear of the
-JU
case.
Construction of the larger PCB follows the same procedure as the smaller
board. The wire links first, then the
smaller components followed by the integrated circuits. Use a socket for U12
so that it can be left out until the
power-up test is successful. The test
points near U14 use PCB pins, and a
small piece of hookup wire is used as a
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The project is built on two printed
circuit boards which are located in a
small metal case. The smaller PCB
(code 9Osst7a) contains the video amp,
sync separator, ADC and power supply
and is placed in the bottom of the case.
The larger PCB (code 9Osst7b) contains
the memory, address counters, control
logic and the transmit circuit and is located above the smaller board.
Begin construction by assemblying the
smaller board. Mount the wire links
first, ensuring that they are straight and
lay flat on the board. Then the resistors
With both boards complete the case
can be soldered in, followed by the
PCB pins. PCB pins are used on both
boards where an external connection is
made.
The capacitors come next, remembering to double check the polarity of the
electrolytics. I used an IC socket for the
ADC, so that the IC itself can be left
out until initial testing is completed.
Next the transistors and diodes are
added, as well as the regulators. These
are mounted so that their metal edge
faces outwards from the board and their
uncut leads only protrude through the
PCB by to 2mm. This allows the leads
ELECTRONICS Australia. August 1990
The D to A resistors associated with
U16 are formed with combinations of
1% or 2% resistors in series.This is
done by inserting one end of the resistors vertically in their holes, soldering
the lower ends in the board, then bending their upper leads inwards, soldering
where they meet and trimming the excess.
114 L----1w
Construction
128
link.
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1
can be drilled. There are five holes on
the rear: one for the DC connector, one
for the RCA audio output socket, and
three for the regulators. Ensure that the
regulator holes are clean and free from
burrs. The location of these holes can
be found by sitting the board on 6mm
spacers and pushing it towards the back,
marking the rear with a pencil through
the holes in the heatsinks.
The bottom board is mounted on
6mm spacers, while the top board is
mounted on a combination of 25mm
and 9mm spacers. The height is governed by the spacing from the bottom
of the top board to the top of the elec-
trolytic capacitors below. The regulators
are screwed to the rear using insulating
washers and bushes.
Wiring can be done using small
hookup wire for all connections, except
Adjust VR6 for a reading of
1500Hz. Now turn the brightness control fully clockwise, push the snatch button and adjust VR5 for a reading of
2300Hz. You may need to repeat this a
couple of times until both frequencies
are correct. Now connect the test link
between C and S (sync) and adjust VR4
for a reading of 1200Hz.
Connect the test link between C and
N (normal), turn the camera controls to
midway, push the snatch button and liston.
t
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,
17-7
Imm
An inside view of the converter, with the larger of the two PC boards clearly
visible along with the overall disposition of parts.
a small length of ribbon cable for the
data bus between the boards. I used a
small length of shielded audio cable between the larger board and the output
socket. I also used the same type of
shielded cable from the contrast control
to the smaller board. The length is
small and I see no problems with this. It
is a good idea to run the wiring so that
the top board can be lifted clear to gain
access to the bottom board at a later
stage.
again and using a frequency meter,
measure the clock frequency at pin 3 of
U15, while adjusting VR3 for a reading
of 2327Hz (approx). Now connect the
frequency meter to pin 4 of U19, to
measure the transmit frequencies.
Turn the contrast control almost fully
anticlockwise
the reason for this is to
provide the sync pulses to the control
circuitry, but no video information.
Turn the brightness control fully counterclockwise and push the snatch but -
-
ten to the audio amp. You should hear
the picture being transmitted as a series
of tones interrupted by the bursts of
sync tone.
Assuming you have a receive scanconverter, you should be able to view your
transmitted picture. But before you get
too carried away in the excitement,
there are a couple of things to check.
Throw the mode switch to single.
1200Hz should be permanently sent.
Now push the start switch; one frame
should be sent and then everything
should stop. Throw the memory switch
to the other position, snatch a picture
and transmit it, checking that it is a new
picture.
Experience will tell you the correct
positions for the camera controls, as
they will vary depending on light and
subject material.
If you have not reached this point
then something is wrong. To do further
testing you will proably need an oscilloscope. By checking the signals at various points on the boards, any problems
hopefully will become obvious.
Although I have not tried one, a colour camera may cause digitising prob-
Testing and alignment
With construction complete and IC's
U1 and U12 stored safely aside, do a
final check of your work. When you are
satisfied all is well, plug in the plug
pack and apply power.
Check the voltages at the outputs of
the regulators. If they are not close to
the required values, check for construction errors. Adjust all trimpots to halfway, solder a link between test points C
(common) and N, and set the mode
switch for continuous.
Plug your video source into the camera socket and connect an audio amp to
the output socket. You should hear a
constant tone, interrupted by a pulsing
tone (horizontal sync). If you get something like this, remembering we have
not yet done the alignment, then all is
well and IC's U and U12 can he inI
serted after powering down.
Solder the test link between C and
B/W (black/white). Turn the power on
!
-
this time a closeup of the smaller PCB with the larger
Another view inside
one swung out of the way. The three voltage regulator chips are at left, bolted
to the rear of the case.
ELECTRONICS Australia. August 1990
129
Scanconverter
lems due to the presence of the chroma
subcarrier. A trap comprising an inductor and a capacitor in parallel tuned to
4.433MHz could be placed between the
camera socket and the contrast control,
to null out the interfering signal.
Components
There should be no trouble in obtaining parts' for this project as they are all
standard components except for the
ADC. I obtained my CA3306 from Radiospares in Sydney. The -memory IC
can be either a 62256 or a 43256 as I
have tried both with success, one having
an access time of 100ns and the other
120ns. I suggest you shop around for
this item as you can buy them at a good
price at some locations.
The plug pack is a bit overated: a 15V
AC 500mA would suffice, but the one
used is readily obtainable.
I used a S0239 socket for the camera
input, as this is the standard type in my
shack, but you could use any type to
suit your video camera. I used inexpensive push buttons to help lower the
overall cost, but a higher quality type
would improve the performance, espe-
An overlay diagram showing the location of parts on the larger of the two PC
boards, and also Interconnection points.
PARTS LIST
1
1
1
1
1
1
1
2
2
1
1
1
metal case 184 x 70 x
160mm
PC board, 124 x 64mm, code
90sst7a
PC board, 148 x 120mm,
code 90sst7b
plug pack 16V AC at 900mA
RCA chassis socket
camera socket (see text)
DC input socket (insulated)
and plug
momentary make push
buttons (see text)
SPDT toggle switches
3.579MHz crystal
18 pin IC socket
28 pin IC socket
Semiconductors
1
6
1
6
1
1
1
1
1
1
130
1N914 diode
1N4002 diode
5.1V 400mW zener diode
BC549 transistors
7812 +12V regulator
7805 +5V regulator
7912 -12V regulator
CA3306 ADC chip
62256 (or 43256) 32K x 8
static RAM
74LS221 dual monostable
ELECTRONICS Australia, August 1990
1
2
1
1
1
4
74LS74 dual D type
74LS02 quad NOR
74LS00 quad NAND
74LS32 quad OR
74LS158 data selector
74LS161 synchronous
counters
74LS123 dual monostable
74LS374 octal latch
4066 CMOS analog switch
555 timer
LM324 op -amp
566 VCO
Resistors
All 1/4W 5%:
1 x 22R, 2 x 270R, 3 x 470R,
2 x 1k, 2 x 1.8k, 3 x 2.2k,
1 x 3.3k, 9 x 4.7k, 1 x 6.8k,
7 x 10k, 2 x 15k, 4 x 22k,
3 x 27k, 1 x 47k, 1 x 68k,
1 x 330k.
All 1/4W 1% or 2%:
1 x 8k (6.8k + 1.2k), 1 x 16k,
1 x 32k (16k + 16k),
1 x 64k
(62k + 2k), 1 x 128k (110k +
18k), 1 x 256k (240k + 16k).
1
1k linear pot
1
5k linear pot
1
1k vertical miniature trimpot
20k vertical miniature trimpot
10k vertical miniature trimpot
1
3
Capacitors
1
2
2
2
12
1
1
3
11
2
1
33pF ceramic
1 nF greencap polyester
10nF greencap polyester
33nF greencap polyester
0.1 uF monolythic ceramic
0.47uF 35V tantalum
4.7uF 35V tantalum
4.7uF 16V electrolytic PCB
type
10uF 16V electrolytic PCB
type
470uF 35V electrolytic PCB
type
2200uF 35V electrolytic PCB
type
Miscellaneous
2 knobs, 3 x T0220 insulating
kits, PCB pins, ribbon cable,
single core shielded cable,
hookup wire, tinned copper wire,
4 x 6mm spacers, 4 x 25mm
spacers, 4 x 9mm spacers,
9-3mm x 12mm screws and nuts,
4-3mm x 50mm screws and nuts,
solder type earth lug.
cially the snatch push button.
The plug pack is supplied without a
plug, so you will need to add one.
When choosing a mating socket ensure
that it is completely insulated from the
case, as both AC wires are above earth
potential.
Operating
Now that you have successfully completed your scanconverter, no doubt
you are eager to get on the air. If you
have looked in on the action before,
you will know that the main activity is
on the 20m band, on 14.230MHz. Some
other likely spot frequencies are
3.670MHz, 7.130MHz, 21.340MHz and
28.680MHz. There may well be some
VHF activity in your area as well.
You may need to construct a switch
box so that you can switch between
your microphone and scanconverter, if
The PCB pattern for the smaller of the two boards. As usual,
actual size for the benefit of those who like to etch their own.
And here's the pattern for the larger board, again actual size. The exact
mounting hole size and location is up to you.
it is reproduced
you have not done so already.
The output level should be initially set
low and increased by adjusting trimpot
VR7, until your transmitter is sending
the required power. Remember that this
signal is of constant amplitude, so avoid
driving your transmitter past its continuous output rating.
A lot of SSTV stations these days use
scanconverters that use an automatic
signal at the start of the frame to set the
correct speed and mode. This unit does
not transmit this code, so that you will
need to tell the receiving end your
mode so they can manually set their
units to receive.
The dual memories are an advantage
when on air. For example you could
store your callsign in one memory,
while using the other memory to snatch
pictures of yourself, your shack or your
favourite cartoon character and then revert to the first memory to identify you self.
In the continuous frame mode you
could position the camera while you are
transmitting a picture, snatch a new picture during the vertical sync pulse, and
so have a continuous flow of pictures
sent.
It is even possible to transmit colour
pictures with this unit, using the frame
sequential method. You will need to obtain red, green and blue filters to place
in front of the camera. Before you
send, arrange with the receiving station
the sequence of frames to he sent: this
is usually red. green then blue.
Firstly place the red filter in front of
the camera and snatch a picture. Using
the single frame mode send the picture
Then keeping the camera and .uhteet
.till..natLh ankl end the _'per .md t.ti..
ELFCTRQNICS Australia
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Scanconverter
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No, we hadn't forgotten
the smaller PCB board.
-
here's the wiring overlay for
pictures the same way. The receiving
station will have received the filtered
pictures and stored them in his three
memories and then combined them to
form the colour image.
So that is it. The unit should provide
some exciting moments for you.
Remember that 14.230MHz is the most
active DX frequency, and is also used
extensively
for
VK/ZL
contacts.
7.130MHz is also popular in VK2 and
VK3 as it provides good short path contacts.
I hope to 'see' you on the air sometime.
Top right: A
closeup of the
rear of the front
panel, showing
the control wir-
ing.
'
-
Bottom right: A
closeup of the
voltage regulators bolted to
the rear panel of
the case, for
correct heatsinking.
1
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49
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90
e=2
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AVO ELECTRONIC SYSTEMS PTY LIMITED
188-192 Pacific Hwy. (Cnr Bellevue Ave.) St. Leonards. N.S.W. 2065
Tel: (02) 901-2655 Fax (02) 906-2735
Training, installation and problem solving specialist
PC XT
Reliable repair and service by qualified engineer
12 MHz CPU
101 KEYS
MONO
CGA
EGA
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KB
$1250
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80 MB
2MBRAM
-
Postscript!!!
'
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PC AT
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20 MB HDD
MONO
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EGA
$2202
VGA
$2290
STORAGE
20
MB
Hardbsk
42 MB VC HDD
&
&
card
card
70 MB VC Harddsk
DISPLAY
546500
Mon
5825.00
EGA card
& CGA
(dual card
PRINTER
ACCESSORIES
575.00
Parasmc 9 pert
5330.00
12'
vela)
Epson 10' 9 pins
538000
Male d1
5250.00
Epson 10' 24 pint
558500
Keyboard draw
57500
5680.00
Joys
53100
x
12' Dgdser
software
159000
58500
VGA
5145000
Due made moose
518600
Star
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52180.00
EGA
mortar
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Epson 15' 24 pints
51280.85
Puler sand
52500
330 M8 ESDI Harddsk
52490.00
VGA
moats
5630.00
Porters
sew box
$4500
Date Storage Box
51800
5720.00
Parer cable
S12.85
360 KB DDSD Dskebd10
51000
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12
52500
100 MB VC
Rebell
360 KB Floppy ó5k chive 513500
12
MB
1.4 MB
Floppy áác
Raspy
Id
be
516500
dine 519500
HOVEL ca<Dtien
518500
ELECTRONICS Australia, August 1990
card (16 8s)
NEC 2A Super VGA
NEC 3D Mulhsya
15'
9 pins
51080.00
Porter sand
40 16'
52180.00
TI
NEC 5D 20'
53630 00
HP
NEC
$2451
$3038
$3674
NOW $9999
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AT
132
MONO
EGA
NEC3D
* 1.2 & 1.4 FDD
VENTURA SOFTWARE & TRAINING
1024 X 768 14" NEC MON
TI LASER
HF Laserjet III Compatible and upgradeable to
RRP :
80286 CPU
12 mHz 0 WS
'Package
r
HDD
PC SX
80386 SX
1024 KB RAM
42 MB HDD
LM = 26 MHz
Full 12 months parts and labour warranty
360KB FDD
20 MB HDD
Laser
lase
READER INFO NO. 31
»
MB DSHD
Dske0ell O
cal
1.4 MB DSHD DsketteJlO
al
Copacesaor from
55000
5250.00
c,
4
_.
t;
-
PC 386'
80386
33 MHz
1 MB RAM
80 MB HDD
LM = 59 MHz
MONO
$4442
EGA
$5029
NEC3D
$5665
PHONEORDER TOLL FREE ÁLTRONICS 008 999 007
°
constructors, hobbyists and
users of rack hardware.
Attention
ALL
Manufacturer makes major BOO BOO
with huge shipment of rack cabinets.
Jack O'Donnell
Managing Director
Massive
savings of
40% and
more.
e
000
Oe a
Á
`as tea
e
5,000
V case5Waae
rces.
r_I
These are actual cases from our latest delivery of the famous
Altronics rack case. They look fine don't they?
1st come first
Well then, what's the problem you ask? Why are they selling so
cheap?
served.
Firstly, the front panels were specified to be anodised. Instead,
the maker has black powder -coated models H 0411, H 0412 and H
0413 and silver alumadised the `natural" models, H 0401, H 0402
and H 0403.
Sale
The actual appearance and finish is to a high standard and
attractive.
Model
So what's the problem?
H 0401
H 0402
Very simply, the majority of these rack cases are sold by our parent
company, Altronic Distributors, to manufacturers and most
manufacturers require (and insist on) an anodised finish to match
with associated equipment when assembling rack consoles.
H
H
H
H
-
Secondly, the lid securing screws don't always line up perfectly
you occasionally might need to drill out a hole or two to get the
screws to fit 100%.
In our view these deficiencies will not bother the average
enthusiast (and perhaps quite a few trade users) and more than
made up for with these fantastic savings.
i
_
.
0403
0411
0412
0413
Finish
Natural
Natural
Natural
Black
Black
Black
Normally
$59.95
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1-5
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Obviously we can't take any
6+
$35.00
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Once they're gone
that's it.
back
orders in this instance.
PHONEORDER TOLL FREE ALTRONICS 008 999 007
PHONEORDER TOLL FREE ALTRONICS 008 999 007
Digital Sine/Square Wave Generator
NEW! NEW! NEW! Another superlative design from the
y
Silicon Chip design team. See Silicon Chip Magazine July '90
The use of modern circuit technology Waveform
'
Synthesis enables this Generator to deliver
performance specifications comparable to commercial
equipment costing $2000 and more.
a
IS¿rta"EENE
IS
. tam
a,w
.a...
This new Digital Sine/Square Wave Generator uses high speed CMOS ICs and a
digital filter IC to produce sine and square waves over the frequency range from
0.1Hz to 500Hz. It also features a 4 -digit frequency readout and an output level
,....v
OP
A TARE
control.
at'
Specifications: Frequency range: 0.1Hz-500kHz in four ranges; 0.1-10Hz; 101000Hz; 1-100kHz; 8 100-500kHz
Output wave forms: Sine and square
Harmonic distortion: Less than 0.15 from 0.1Hz-50kHz; 0.27% at 80kHz
Square wave rise time: 1Ons
Square wave fall time: ions
Output level:
meoaasc. aoaras
a
K 2547
Sine wave; variable from 0-1.2V RMS; Square wave; variable from 0.5V p -p
$175.00 VALUE
How many times have you opened up that favourite board game to find that someone
has pinched the dice? In that case, why not build this elegant electronic dice which
uses lust two CMOS ICs? It simulates the roll of a real dice and even turns itself off.
4
Build this elegant
separate channels-up to 30 seconds per channel record/playback time.
This Digital Recorder delivers astonishing reproduction of voice and/or music
without one single moving part!
Electronic Dice
Digital ,),(icole.beflcorde_
-
LED readout simulates a "dice"
Great fun to build.
see Silicon Chip July 90.
f/-
Output impedance: 60011 nominal Load Impedance; 600 to infinity
Protection: Short circuit protected (indefinite) Display accuracy: +1.2%
+!digit
Í 0111E
a
r.r
`
.
f
af
r
«
inttlk
K 1140
$29.50
Build this
for the kids!
The specifications of this excellent design compare very favourably with commercial
test equipment costing $300 and more. A very worthwhile addition to your workbench.
Digital Capacitance Meter
"Silicon Chip"
May '90
Superb
test
E
--
DIGITAL CaP*C1/ANCE METER
Capacitance IpF to 999911F in seven ranges
Designed for laboratory and workshop use
HERE
»e a
K 2524
`*j
1
digit
(See EA Aug 85)
occurs.
Battery backup is provided so that the messages are retained when main power is off.
Typical applications include:
Alarm system messages
Sales messages for customers put 'on hold'
Experimental telephone answering machine Door station announcer Talking
displays for shops
Emergency warning message announcement
Operation instructor for machinery etc.
Countless other applications where voice
or music Is required
5100's cheaper than imported digital recorders
$129.00
For those who want a professional appearance - stand alone product, we can supply with
our Deluxe H 0483 Instrument case and fully punched and screen printed front panel
complete - with Inst. case
$149.00
1
y
Laboratory Power Supply Kit
EA May'85
Over 500 sold
Po
1
-
a
99.99µF in
3 ranges
rrne.eos
Five years is a long time in the electronics world and that's how long our K 2522 Digital
Capacitance Meter kit has been popular. However, we have to make room for the new
Silicon Chip model by selling the few K 2522 kits that we have left for an incredible
560.00. Order one while you can and save a bundle'
K 2522
=
Here is a digital voice recorder that can store 4 different signals, voice. sound or a music
source of up to 30 seconds each or one recording of up to 2 minutes.
There are 4 trigger Inputs so that a message can be retrieved when a certain condition
.K 9555 Kit
Mains powered
Digital Capacitance Meter
Measure pf
!
111111111
$1 20.00
YOU ARE BARGAIN HUNTERS!
CAPACE7Aail`p
.
.
K 9550 Kit complete - PCB Format
t:
etyulpovi
Ñ.4
Accuracy +/- 1%, +/-
r
\. ...+lrry
,-.-4,440=11.7
.r
Includes Jiffy box.
si,rtiwEsr
a.
NOW ONLY $60.00
i
1
talsrls
-
3 to 50Volts at 5Arnps
Single PCB
very easy to build
Floating output
Super low ripple voltage
High efficiency TOROID transformer is used
K 3301 10
turn O/P control $29.50
outputs $14.50
K 3302 +1- 12V Aux.
For the engineer
and hobbyist
ik
Aá::
$195.00
PHONEORDER TOLL FREE ALTRONICS 008 999 007
PHONEORDER TOLL FREE ALTRONICS 008 999 007
Highly recommended for
40MHz Dual Trace Oscilloscope Service Workbench, Design Laboratory, Manufacturers,
Universities and the dedicated Enthusiast.
CRT Display 150mm rectangular, domed mesh and 12kV post accelerator type.
Vertical Amplifier (CHI and CH2 identical) Operational Modes: CH1, CH2, ADD. DUAL, ALT,
CHOP Sensitivity: 5mV - 5V/Div 3% In 1-2-5 steps, 1 mV - 1V/Div 5% X5 Mag
Horizontal Amplifier Operating Modes: X -Y operation CH1-X axis, CH -2 Y axe Sensitivity: 5mV
- 5V/Div +/- 3% in 1-2-5 steps
Input Impedance: 1MOhm+/- 2%, 25pF +/- 3%
Time Base Sweep Method: AUTO, NORM, SINGLE Magnified Sweep: 10 times +/- 5%, Max
20nS Delay Method: Continuous delay and adjustment
Synchronization A, B, B Triggered, Internal V -MODE, CHI, CH2. LINE, EXT
Trigger Coupling: AC, DC, HF Re*, TV -H (Line), TV-V (Frame) Triggering Sensitivity: INT. DC 20MHz 1.0 Div, 20MHz - 40MHz 2.0 Div, EXT. DC - 20MHz 150mVp-p, 20MHz - 40MHz 300mVp-p
Vertical Amplifier Signal Output: 50 mV/Div. - 50 Ohm
Intensity Modulation Z Axis Bandwidth: DC - 1MHz, Senskivity3Vp-p
N//fóv
Probe Calibrator Output : 1 kHz square wave 1V
Price includes TWO X1/X10
Probes worth$100.00!
$1 495.00
Q 0160
DUAL TRACKING POWER SUPPLY
SILICON CHIP APRIL'90
+/- 50V
r-tiratroil._ _.._
t
.
ta
.`
nr
,
'90
DC AT 1.0AMP
17 Range Digital
Multimeter
100V
Current
output1.7A from 0 to 87V
(+/-43.5V)
1 A from 0 to 100V (+/-50V)
ripple)
K 3380
with Overload Protection
n
Australia's best value, less than $50
,
Speclfutlon:
Yisr,
DC Voltage Range: 2V.
20V, 200V, 2003V
AC Voltage Range:
200V, 500V
DC Current Range:
HUY
/N
'90
$ 229.00
20mA,
l0A
RalataneeRange:
2000hnt 2kOhm,
201cOhm,200kObm,
2MOhm
Laboratory Series Audio Oscillator
D iode
/N
a3
t]
1547
$480
á
Tat
Test Current: 1.0 +/6mA
Test Voltage: 3.2V Max
Battery Tat Range:
1S V, 9V
/VfGI/,
'90
^
A
Voltage output: o to +/-SOV or 0 to
Load regulation, better then SOOmV
+1-50V, IA
Drop out indicator (SmV of
Short circuit protection
Load switch - m need to switch off
when switching load.
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JJJ
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-
11,___-sesv.
Frequency Range: 20Hz to 200kHz in 4 ranges
Sine Wave Characteristics: Output voltage: 5V RMS or more at no load Distortion factor (at
max output) 0.5% or less Output impedance: 600 Ohms +/-10% Output attenuator: 0 to greater
External Synchronisation Characteristic* Input
than 50dB continuously variable,
Reading Accuracy
Impedance: approx. 10kOhrns Max. allowable input voltage: 10V RMS
Frequency Counter Characteristics Display: 4 digits, 7mm red LED
0.01%, +/-1 count
display Frequency range: 10Hz-1 Mhz (square wave) Sensitivity: 25mV RMS Max. input: 150V pp Input Impedance: IMOhm Square Wave Characteristics (TTL Out) Overshoot: 2% or less (at
Power roquirenrnta: 1001120/220V +/-10%240V +5%,
1kHz) Rise/fall time: 200n sec or less
$49.95
01056
Another Altronics Direct
Import Price Breakthrough
Carry Case 0 1057
-10%,46-66Hz
$
1
2.50
INVERTERS
INVERTERS INVERTERS INVERTERS INVERTERS
sets
Get 240V AC Mains Power from your battery with these handy inverter kit
POWERHOUSE
Many combinations to choose from:
600W
This inverter he. the capacity to produce 600
watts of mains power which will run a fantastic
array of appliances. Ideally suited to running
power tools, lighting (including tiaras) electr
motors and much more. It C11121 used either as a
portable or a permanent future.
Low battery
Menial ar Auto Start facilities
Cut -Out
$425.00
INVERTER
WITH AUTO START
I
a
:417..t.
e
Kit version
K 6770
300 WArr
A.14.1
NVERTER
I
(See EA Dec'87)
s
`
al--_
'
Operates from 12V Car Battery
Auto Start draws power from you
battery only when appliance is
plugged in and 'turned on' ie.
battery can be left permanently
Voltage
connected if required.
Current Regulated
Regulated
Current Overload unit self limits
Complete Kit
F>
xer.rw
Fully built and tested
12V Input K 6774 $525.00
24V Input K 6775 $525.00
K 6750
$279.00
Fully built
and tested
K 6755 $379.00
100's OF USES AT HOME AND AWAY
PHONEORDER TOLL FREE ALTRONICS
0118 999,
007
PHONEORDER TOLL FREE ALTRONICS 008 999 007
Two Brilliant New Multitesters From
Bargain Auto Ranging
Altronics at Low Direct Import Prices
Digital Multimeter
Specifications For Q 1066 / Q 1070
Engineering Multimeter Testers
DC
Voltage Range: 200mV, 2V, 20V, 200V, 1000V
+ 1 dgt
Accuracy: All ranges +/- 0.5% rdg
Input Impedance: 10MO
/N
'90
Range: 200mV, 2V, 20V, 200V, 750V
Input Impedance: 10MS1
DC anaet Range: 200uA, 2mA, 20mA, 200mA, 10A
AC anent Range: 200uA, 2mA, 200mA, 10A
Resistance Range: 2000. 2k0, 20k11, 200k0. 2M0, 20M0, 2000M0
Capacitance Range: 2000pF, 20nF, 200nF, 2uF, 20uF
Transistor WI Beee DC Current: 10uA, VCE: 2.8 +1- 0.4V
Oeeerel: Display: 3 1/2 digit liquid crystal with maximum reading of
1999 Overrenge Indication: Highest digit of (1) or (-1) is displayed
AC Voltage
ft
:r
;
.or
r1Us
Why pay double
the price for Fluke?
nnn
.0 u u
See our catalogue for full features and
quality of this excellent Labtech Auto
Ranging Digital Multimeter
tsr
v
hado
1075 Normally
la.. badQ
.
Q 1070
Temperature Range: -20'C to 750'C 0'F to 1400'F
Accuracy: +/- (3' + 1 dgt) up to 150'C +/- 3% rdg over
150'C +/- (15' + 2 dgts) up to 225'F
$189.00
only $89.50
Including FREE carrying
case Q 1076 or Holster
0 1077, 012.50 value,
makes a total saving of
V t2ats
COSA
Logic Test (01070 only) Logic 1: 2.4V +/02V, logic 097V +/- 0.2V
FrequencyRenge: 2kHz, 20kHz, 200kHz,
2MHz, 20MHz
Input Sensitivity 20MHz range 1V rms.
Other ranges 35mV rms.
$22.50 SAVE! SAVE!
3,31
Fluke is the registered name of Fluke
Instruments USA.
fete .
AVIATION
HEADPHONES
Q 1068 Carry Case $12.50 (suit
0
1066&
0
1070)
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1066$149.00
Q 1067 Temp. Probe for Q 1066 $29,95
ordered this month
Why pay $400 or more for a
David Clark set?
BENCH AMP SIGNAL TRACER
See EA April '88 Another Altronics Kit Special!
0111U1
AVIATORS HEADSET
WITH OIL FILLED EAR
CUSHIONS
"
High performance, noise attenuating
Noise cancelling microphone
Cushioned head pad Super sturdy Great
performance. Superb, professional pilot's
headset will last a lifetime with rea,00able
treatment. Includes standard aircraft jacks.
4/".."«.1
33313
h.aat, s,.e
earphones.
Here is a simple but effective audio bench amplifier. Ideal for
fault finding and experimenting and s000 inexpensive.
C9070ONLY
$189.00
Features:
Input range 10mV to 10V in 4 ranges
Inbuilt speaker and external
speaker socket
Overload indicator
Requires external 9-15V AC supply
OVER
Normally $65.00 FREE this month with each
2565 RP Probe kit worth $12.00
K 2100
kit,
K
Polypropylene Bass Drivers
12" (300mm)
WOOFER
a
'A
but definitely the BEST VALUE we know of - ANYWHERE.
Normally $99
10" WOOFER
60Watt RMS
100W Max.
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C 3065
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ONLY
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Massive 200 W
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Our ALL NEW 'Black' polyprop cone Bass Drivers exhibit quite astonishing low
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\
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This month
Logic Tester, Frequency
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Multimeter with Temperature Meter,
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Q
`'I"
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rh
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if
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,1,1
,,/
ffrl
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AT $22.00
C 3045
PHONEORDER TOLL FREE ALTRONICS 008 999 007
PHONEORDER TOLL FREE ALTRON.ICS 008 999 007
Harris Four Channel Digital Recorder/Announcer
The Harris A2100 provides 4 channels of natural speech recording and
Record time for each channel Is Internally selectable to 10, 15,
play -back.
Channels can be used separately or linked to provide
20 or 30 seconds.
one long recording/announcement.
with the recorded announceInterrupt
ments as desired.
Nicad battery backup fitted for memory
retention.
Facilities/Features
Microphone Input - balanced line, low Z.
Auxilhary Input - 100KOhm 0.2V
sensirivity, e.g. for CD, tape deck, Tuner,
BGM line.
,
"!-T
Music on Hold Adviser - Over 50% of
phone calls are placed on hold - use this
time to promote your business or
products.
Information Guide - Great for displays,
trade shows, sell guided tours and even
art galleries.
A Security Guard - Good weather or bad,
holidays and weekends, it stays on duty
24 hours a day to query and direct all
personnel at stores, wharehouse, plants,
offices, hospitals and parking facilities.
And for apartments, hotels, estates and
more - whenever you wish to screen
traffic.
This refined car burglar alarm has
about every feature you could
possibly want to keep would-be
"c
VAT
7
Y.ap+a.w[.
Wily,
'9ó
A 2100 Great Value
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Features:
Internal and external
sirens
Dual lamp flasher
Delayed and
Battery back-up
non -delayed Inputs
Easy to build
o
p
EA March/April '89
One PCB
Kit includes 1.2AH back-up
Easy to build
Lamp tellPanic alarm input
battery
Entry, exit delay
Key
tale outputs
Auxiliary relay for external siren etc
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Uses most types of sensors.
and install.
00
K 1910 Kit less siren
S -5170 Screecher Siren 110db $24.95
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With each car alarm kit purchased
this month we will include four (4)
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e
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Installing your own alarm system. It's so
Inexpensive!"
Silicon Chip Feb '88
WAS $129.00
,-
Emergency Signals - and/or security
warnings can be generated
automatically or at the push of a
button.
Advertisement Announcer for Retail
Stores - Either record you own ads or
have them commercially produced play through your PA/BGM system as
often as desired with the interval time.
The Protector
Car Alarm Kit
K 4370
Harris Digital Recorder Annwmeer
Literally dozens of applications
Channel Select Pushbuttons - A, B, C, D
or A+8+C+D, i.e. when activated will
playback whichever is selected.
Sequential Pushbutton - enables
playback of each channel in sequence
via the Timer Switch.
Timer Switch - automatically initiates the
play back of the selected channel.
Intervals are 10, 20. 30 seconds, 3, 6, 12
and 30 minutes and off.
Remote microphone operation and PTT.
Remote switch message actuation Input.
Line In/Line Out - zero gain circuit
enables you to pipe' a music source
such as BGM or tuner, cassette deck etc
through the recorder. This line will
Designed around the TMS 3477 digital recorder IC,
this brilliant Australian made recorder has no
moving parts and will play indefinitely.
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Chances are there is an Altronics Reseller right near you - check this listthe
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may
freight and insurance and therefore the prices charged by individual Dealers
will
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prices
Dealer
however,
in
many
cases,
vary slightly from this Catalogue -
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MORE ALTRONICS DEALERS WANTED
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significantly by becoming an Altronics Dealer, Phone Chris
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If you have
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virtually
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please
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order toll free up to 6pm Eastern Standard Time. Remember with our Overnight
Jetservlce we deliver next day.
-
-All
-
-
item for you.
412681 ESPERANCE Esperance Communications 713344 GERALDTON Bird
ALBANY BP Electronics
212777 KARRATHA Daves Oscitronic 854836 PORT HEADLAND Ivan Tomek Electronics
KALGOORLIE Todays Electronics
ALICE SPRINGS Ascom Electronics 521500 Farmer Electronics 522388 DARWIN Ventronics
732531 WYALKATCHEM D & J Pease 811132
VICTORIA CITY All Electronic Components 6623506 SUBURBAN
ACT CANBERRA Bennett Commercial Electronics 805359
480030
BENDIGO
7233860 PRESTON Preston Electronics 4840191 COUNTRI
CHELTENHAM Talking Electronics 5842386 CROYDEN Truscott Electronics
CAPALABAKmgsway
CITY
Delsound P/L 8396155 SUBURBAN
346133
QUEENSLAND
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Electronics
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411411
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Electronics 3902399 WOODRIDGE David Hall Electronics 8082777 COUNTRY
COUNTRY
WA
Electronics 641631
724459
MACKAY
Philtronics
578855
ROCKHAMPTONAccess Electronics
(East St.) 221058
TOOWOOMBA
Hunts Electronics
SA CITY Force Electronic 2125505 SUBURBAN
7724466 MAROOCHYDOREMaIs Electronics 436119
329677 TOWNSVILLE Soles
3496340 FINDON Force Electronics
3823366 ENFIELD Force Electronics
3770512 CHRISTIES BEACH Force Electronics
BRIGHTON Force Electronics
MT.GANABIER South East Electronics 250034 WHYALLA Eyre Electronics
3260901 COUNTRY
3471188 LONSDALE Force Electronics
NSW CITY David Reid Electronics
316533
342233 LAUNCESTON George Harvey
HOBART George Harvey
454764 TASMANIA
Tomorrows Electronics
COUNTRY COFFS HARBOUR Coffs Habour Electronics 525684GOSFORD
Hlcom Unitronics 5247878
2671385 CARINGHAH
247246 GRAFTON East Coast Electronic 431250
Electronics 873419 WINDSOR
Electronics 216558
M & E
Electronics 775935
NEWCASTLE
Novocastrian Elect.Supplies 621358
WOLLONGONG Newtek Llectronics
271620
RAYMOND TERRACE
Vimcom Electronics 284400
WAGGA WAGGA
Alback
Phillips
007
PHONEORDER TOLL FREE ALTRONICS 008.999
Digital Stopwatch
with lap timing
.111
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Here's the design for an easy to build four -digit timer counter, which can be used for.
applications such as a stopwatch, event or racing lap timer. It uses two readily available
modules, which can be purchased as kits.
by ANDREW PALMER
Clive Chamberlain and his boffins at
Australian Test & Measurement have
been at it again. This time they've produced a module which mates with their
existing ATM13 four -digit general purpose counter module, to produce a
stopwatch/event timer.
In combination the two modules will
count time periods up to 9999 seconds,
and with resolutions of down to 10 milliseconds. They do this in three ranges:
range 'A' reads from 0 to 9999 seconds
with a resolution of 1 second, range 'B'
from 0 to 999.9 seconds with a resolution of 100ms (1/10th second), and
range 'C' from 0 to 99.99 seconds with a
resolution of 10ms (1/100th second).
As well as performing normal start/stop single period timing they also provide a 'Lap time' function, allowing you
138
to freeze the reading at a particular instant while the main tinter is still counting, to keep track of the overall event
time.
The timebase for the counter is derived from a low-cost quartz crystal, giving a timing accuracy of around .001%.
This means that the effective accuracy
on all ranges is basically the same as the
resolution.
These features make the resulting
stopwatch/timer suitable for a wide variety of timing applications, from the timing of races and other sporting events to
things like checking human reaction
times and timing industrial processes.
The new module is called the
ATM15, and is designed to mount 'piggyback fashion' onto the top of the
ATM13 module, plugging into the two
ELECTRONICS Australia, August 1990
SIL sockets provided. This forms a very
compact assembly, which will then fit
into one of AT&M's neat and rugged
little extruded aluminium cases.
The electrical inputs to the timer can
be fed from either CMOS logic signals,
or from simple pushbutton switches.
The decimal point of the 4 -digit display
can also be set to correspond to the desired reading range, as desired.
In short, the ATM13/15 combination
makes a very flexible and handy little
stopwatch/event timer
but one that is
at the same time easy to build, and very
reasonable in price.
-
Circuit description
The operation of the basic ATM13
four -digit counter module has been described in Electronics Australia before
4
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circuit schematic for the new
stopwatch/lap timing module is shown at
top, with the PCB overlay above and a
top view of the module at right, plugged
into the counter module.
The
it formed part of the 'Digital Ampllometer' project, in the April 1990
issue. However to recapitulate, it's
based on the National Semiconductor
MM74C926 chip. This is an LSI four
decade counter/latch/decoder, with inbuilt display multiplexing for a four
digit, 7 -segment display (0000-9999).
Multiplexing, you may recall, is where
the contents of the four cascaded BCD
decade counters and their latches are
applied sequentially to a single BCD/7segment decoder and display driver,
with the driver effectively switched to
each of the display digits in synchronism. This technique saves both power
and components, and results in high efficiency.
In the ATM13 module (Fig.1), the
MM74C926 is arranged to drive four
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high efficiency 7-segment common cathode LED displays, via digit driver transistors 01-4. The displays have digits
12mm high and produce orange -red
635nm output. This gives a high apparent brightness, which can be improved
still further by using a red or orange filter. There is no flicker due to the multiplexing, as the MM74C926's internal
multiplexing oscillator sequences the
digits at a rate of around IkHz.
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The decimal points for the three most
significant digits are brought out separately, to allow hard wiring as desired.
In addition the ATM 13 has three discrete LEDs (LEDI-3) to the right of
the main four digit display, for indication of other functions such as range or
measuring mode.
The MM74C926 counter is negative edge triggered, via the CLK input. It
can count at rates of up to about 4MHz.
ELECTRONICS Australia. August 1990
139
Stopwatch/timer
PARTS LIST
ATM13 module
Resistors
J1,J2
0 -ohm links
R1,2,3,4,5,6,15,16,18,19
1k 1/4W
87,9,10,11,12,13,14
470 ohms
Capacitors
47uF/16V electrolytic
Cl
100nF ceramic
C2
Semiconductors
S1,2,3,4TDSO5160 7 -segment
displays
LED1,2,3
3mm red LEDs
MM74C926 counter
U1
Q1,2,3,4
BC550 transistors
Miscellaneous
K1,K2 10 -way socket strips
40-pin length right-angle pinstrip
PCB13A00 and PCB13B00
boards.
ATM15 module
Resistors
J1,2,3 `0 -ohm' links
R1,4,6,810k 1/4W
R10
10M 1/4W
R2,3,5,7100k 1/4W
R9
A +5V signal on the RST input clears
all counters to '0000', while a similar
+5V signal on the LE (latch enable)
input places the latches into a flow -
produced in prodigious quantities and
hence available at low cost.
The crystal frequency is subsequently
divided down by the chip to produce a
100Hz output. Further division here by
10 and 100, using a dual decade divider
type 74HC390 (U4A/B), gives 10Hz and
1Hz. This gives our three basic timebase
signals, which are selected by LK2 to
provide the three timing ranges
chosen to suit the expected duration of
the event being measured.
In position 'A' (100Hz) the full scale
count is 99.99 seconds with 10 milliseconds resolution; in position 'B' (10Hz)
it is 999.9 seconds with 100ms resolution; and in position 'C' it is 9999 seconds with 1 second resolution.
The timebase frequency selected by
LK2 is gated to the ATM13 by gate
U2:D, controlled in turn by the
START/STOP flipflop U1:B. The
pulses passed by U2:D are fed to the
ATM13 module's CLK input via pin 16
of connector K2.
The inputs START, STOP and LAP
have pullup resistors R4, R6 and R8
which are followed by differentiator CR
networks C3/R3, C4/R5 and C5/R7 respectively to give short, standard length
pulses. The START pulse is fed directly
to the SD input (pin 10) of U1:B, to
begin the counting, while the other two
signals are fed via Schmidt gates U2:B
and U2:C to sharpen up the waveform
to suit the risetime requirements' of the
CLK inputs of U1:B and U1:A.
Whereas U1:B is the main START/
STOP counter control flipflop, U1:A is
the lap timing controller. Basically it
.
through (transparent) condition. Alternatively a GND signal on the latter
input will latch the count held in the
counter into the output latch.
A +5V signal on the DS (display select) input will display the current number in the counter, while a GND signal
on the same input will show the number
held in the latch.
Generally LE and DS are set to GND
to display the contents of the latch and
a short pulse to +5V on the LE will
transfer the contents of the counter to
-
the latch.
The CO (carry out) pin of the
MM74C926 is held at GND for counts
between 0000 and 5999, but goes to
+5V at a count of 6000. It then returns
to GND after the count of 9999, indicating that the maximum count of the
chip has been exceeded. On the ATM13
module this line is brought out on bus pin K2/20, for optional use to drive an
overflow LED
or further counting
-
decades.
So much for the basic counting section. Now let's look at the circuit of the
new ATM15 stopwatch/timer module
(Fig.2).
The heart of this is a crystal controlled oscillator, based on the very
handy MM5369EST chip (U3)
again
made by National Semiconductor. This
uses an American standard (NTSC) TV
colour burst crystal of 3.579MHz, a type
-
1k 1/4W
Capacitors
C1,2,3,4,5,8
ceramic
33pF ceramic
0.1 uF
C6,7
Semiconductors
U1
U2
74HC74 dual flipflop
MC14093 quad NAND
gate
U3
MM5369EST
U4
oscillator/divider
74HC390 dual decade
counter
LBU
10 111000
D2
_
D3
--
DP
DP
DP
ON
01
02
03
0
0
04
Lio
20
LE
RST
DS
3
CLK
E
D
C
+5
-
Just for the record, and
to help in following the
story, here's the circuit
schematic
(opposite)
and
the
two
PCB
overlays for the original
4 -digit counter module.
As you can see it's
based
on
Motorola's
MM74C926 counter chip.
RBUS
B
1'ifl
F
10
A
11
>o
PCB 13A00
,.1,5uauwa
K3
Miscellaneous
X1
LK1
LK2
K1,K2
K3
3.579MHz crystal
4 x 2 pin link block
3 x 2 pin link block
10 -way pinstrips
16 -way header (for
S4
PCB1500 board,
140
ELECTRONICS Australia, August 1990
S
Si
R R. LI 880
0
ATM 13)
2 x jumper links
S3
B
F
GBC3ECD+D3
PCB
0
13800
D2
K® A-1
ODl
C>D2
CeD3
J
Cl C2C4ACA3A2Al
I
controls the LE input of the MM74C926
on the ATM13 module, via pin 19 of
K2. Normally the LE input is held at
+5V by the Q-bar output of U1:A (pin
6), but when this flipflop is toggled by a
signal from the LAP input, the LE line
is taken down to GND and the current
MM74C926 count 'frozen' in the
latches. A further pulse from the LAP
input will toggle U1:A back to its original reset state, restoring the LE line to
+5V and re -enabling the MM74C926
latches to their transparent condition so
the total count can be seen again.
LK2 selects the appropriate timebase
frequency, as already explained, while
LK1 allows adjustment of the displayed
decimal point.
A power -on reset pulse is generated
by R2/C1, and fed to the ATM13 module via U2:A and K2 pin 18 to clear the
MM74C926 counters to `0000'. The
same power -on reset pulse is fed to flipflops U1:A and Ul:B, to make sure
they are initialised.
A return to the reset state may be
produced at any time by grounding pin
14 of K2. This is brought out on the
ATM13 module to pins 'D' of the 16 pin rear connector K3, which is for external connections.
In the same way the START input is
brought out to K3 pins 'A', the STOP
input to pins 'B', and the LAP input to
pins 'C'. The only other connections to
K3 are the '+5V' and `GND' power inputs.
The Q outputs of U1:B and U1:A are
connected to LED1 and LED2 respectively on the ATM13 module, via K1
K2
pins 2 and 3. This results in LED1 displaying the timing status, while LED2
illuminates when the LAP function is
enabled.
These are all then soldered. Next the
IC, followed by the transistors, the two
socket strips and the capacitors
making sure you fit CI with the correct po-
Construction
larity.
Finally fit the
The ATM13 counter module consists
of two PCBs, the counter/driver 13A00
and the display board 13B00, which are
joined together by two 10 -way right
angle pinstrips for electrical connection
and mechanical rigidity. The connections between the ATM13 and the
ATM15 module, which is a single
board, are made via two more 10 -way
pin strips and sockets soldered either
side of the PCB.
It's probably best to begin assembly
with the ATM13 boards. Load the
smaller PCB first, by inserting the displays with the decimal points nearest
the two rows of connector holes. Solder
neatly, avoiding solder bridges and dry
joints. Next the LEDs can be loaded,
with the longer anode leads to the right
hand side of the PCB.
The 40 -way right angle pinstrip supplied must be snapped into four strips
of 10 pins, two of which are loaded with
their 'short ends with insulator' into the
front of the small PCB, with their
longer ends pointing downward. Then
solder the pins to the rear copper, making sure the strips are pushed down with
their insulator strips against the front
surface of the PCB.
The main 13A00 PCB can now be
loaded, using the overlay to locate the
inresistors and two '0 -ohm' jumpers
dicated by a single dark central band.
-
-
16 -way connector K3 to
the rear of the board, securing it with a
couple of 6BA screws and nuts before
soldering the pins. Note that each pair
of pins are connected in parallel, to improve current -carrying capacity.
The two PCBs of the ATM 13 can
now be joined by pressing the 10 -way
display PCB connectors down into the
counter PCB. Line up the two PCBs
carefully at right angles, and solder into
place.
You can now turn to assembling the
ATM15 module. As before it is good
practice to load and solder the components in order of height, so start with
the resistors followed by the capacitors,
ICs, and crystal.
Hold the crystal leads with a pair of
long nosed pliers before bending the
leads, to avoid fracturing the glass seal.
They should be bent at 90°, about 4mm
from the seal. The crystal can be secured to the PCB with a bit of double sided tape, before soldering the leads.
At this stage prune all leads on the
bottom of the PCB to be level with the
solder bumps.
The final step is to add the LK1 and
LK2 link pin connectors, and the 10 way pin strip connectors K1 (L-bus) and
K2 (R-bus). These are all pushed
through from the top of the PCB, and
soldered on the underside.
Note that the ATM 15 board is dou-
UI
MM74C926
RBUS
20
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13
14
1$
14
11
CLK
LE
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SCH13OO
ELECTRONICS Australia. August 1990
141
Stopwatch/timer
ble-sided, but for economy doesn't have
plated -through holes. It's therefore necessary to solder a number of component
leads and IC pins to the top tracks, as
well as to the underside. The leads and
pins to be soldered on the top should be
fairly clear from the clear areas in the
solder resist layer, so that you've probably soldered them already. But it's a
good idea to check at this stage, just to
make sure; the circuit won't work if
these joints aren't soldered.
.`
;,,,,,,M1
Testing
To try
ATM15
ATM13.
around,
things out, plug the completed
board into the top of the
It will only plug in one way
with the crystal towards the
rear.
Now connect the '+5V' and `GND'
pin pairs on the ATM13's rear connector K3 to a suitable 5V DC power supply, and also connect four normallyopen pushbutton switches from pin pairs
A, B, C, and D respectively, to the
GND pins. The easiest way to make all
of these connections is via a 16 -way ID type socket, and a suitable length of ribbon cable.
Turn on the power, checking that the
main display shows `0000' and that none
UV PROCESSING
EQUIPMENT
KALEX LIGHT BOX
Autoreset Timer
2 Level Exposure
Timing Light
Instant Light Up
Safety Micro Switch
Exposure to 22in x 11 in
$850.00
PCB PROCESSING
KALEX ETCH TANK
Two Compartment
Heater
Recirculation
(by Magnetic Pump)
Two Level Rack LId
$750.00
3M Scotchal Photosensitive
Riston 3400 PCB Material
All prices plus sales tax
ALEX
H
applicable
Ave,II
q
40 Wallis
East Ivanhoe 3079
(03) 497 3422
497 3034
Fax (03) 499 2381
ELECTRONIC COMPONENTS & ACCESSORIES
SPECIALIST SCHOOL SUPPLIERS
READER INFO NO. 33
142
411
AT&M also makes available this very neat little packaging kit for the timer,
based on a section of rugged aluminium extrusion and two laser -cut plastic
plastic end bezels.
of the three annunciator LEDs (LED1and cause LED2 to turn off. As before
3) are illuminated. The display should
button 'B' should stop the timer and
also remain static, at this stage.
turn LED1 off again, with the final tim-
If you have a 'scope or frequency
counter, check for 100Hz clock pulses at
pin 1 of U3, then 10Hz pulses at pins 3
and 12 of U4, and 1Hz pulses at pin 13
of U4.
Position the jumper for link LK2 to
suit the expected duration of an event
of interest, and that for LK1 to position
the decimal point indication as desired.
Check that the appropriate decimal
point glows, as it should.
Now press the pushbutton switch connected between K3 pins 'A' and GND.
The timer should begin counting, with
the display incrementing at the rate selected by LK2. At the same time, annunciator LED1 should illuminate.
Pressing the pushbutton connected from
pins 'B' to GND should stop the count,
with the display left indicating the
elapsed time and LED1 dark again.
Pressing the pushbutton connected between pins 'D' and GND should reset
the timer back to a display of `0000',
ready for another timing cycle.
If you then start timing again by
pressing the 'A' pushbutton, and after a
few seconds press pushbutton 'C', the
display should freeze at the appropriate
intermediate 'lap' count, with LED2 illuminating as well as LED1 to indicate
that the circuit is now in lap timing
mode. Pressing the 'C' button again
should restore the main timing display,
ELECTRONICS Australia. August 1990
ing count displayed.
If everything behaves as just described, your stopwatch/timer is operating as it should. If not, the odds are
that you've made a wiring error
perhaps not soldering one of those component leads on the top of the ATM15
board, or installing one of the IC's the
wrong way around.
In normal use, the stopwatch/timer
can be operated using pushbutton
switches as just described. However it
can also be controlled from other equipment, using 5V logic signals
preferably HCMOS, and with the active signal
being a transition from +5V to GND.
AT&M also has available an infra-red
beam detector module kit, ATM20, two
of which could be used as optical sensors, to operate the START (A) and
STOP (B) inputs. This would allow elegant sensing of runners, racing cars or
bikes, items moving past on a conveyor
-
-
belt, or whatever you're timing.
As noted earlier, there's also a rugged
extruded aluminium packaging kit available for the ATM13/15 combination,
with front and back plastic bezels already laser -cut to suit. AT&M call this
kit the HWK/UB70, and it comes complete with a red -orange filter to improve
the contrast of the LED display
as
well as finishing the front panel.
-
Happy timing!
!
04%CCO
kfry
po4
e, r
289 Latrobe Street,
e
s.
MELBOURNE
PHONE: (03) 602 3499 FAX: (03) 670 6006
FREE T. E.C.S. WHOLESALE
PRICE LIST (SEND BUSINESS CARD)
ON OUR COMPLETE
RANGE OF PRODUCTS
COMPUTER
SYSTEMS
8MHz
AT
XT TURBO
80286-12 12MHz
V20 8MHz processor
- 640K RAM (Exp. to 1 M)
- 360K FDD
- 1 Serial port
- 1 Parallel port
- Games port
- Real Time Clock
- Mono Graphics Card
- TTL Dual scan Mono Monitor
- 101 Keyboard
- Baby AT style case
-
-
200W power supply
-
DOS 4.01
-
Suntac 286-12 12MHz Chipset
1M RAM (Exp. to 4M)
-
1.2M FDD
-
20M 49mS HDD
2 Serial ports
1 Parallel port
1 Games port
-
-
On Board Real Time Clock
16 Bit 256K VGA Card
- VGA Monitor
- 101 Keyboard
- Baby AT style case
- 200W power supply
- DOS 4.01
-
-
AT NEAT286-16 16MHz
NEAT 286 16MHz Chipset
1M RAM (Exp. to 8M)
- 1.2M FDD
- 40M 28mS HDD
- 2 Serial ports
- 1 Parallel port
- 1 Games port
- On board Real Time Clock
- 16 Bit 256K VGA Card
- VGA Monitor
- 101 Keyboard
- Baby AT style case
-
-
200W power supply
-
DOS 4.01
$1100.00
$2450.00
$2850.00
80386SX 16MHz
80386-20 20MHz
80386-33 33MHz
-
386SX 16MHz processor
1M RAM (Exp. to 8M).
-
1.2M FDD
-
40M 28mS HDD
2 Serial ports
1 Parallel port
1 Games port
-
-
-
386 20MHz processor
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386 33MHz processor
-
1M RAM (Exp. to 5M)
1.2M FDD
-
1M RAM (Exp. to 8M)
-
128K cache memory
40M 28mS HDD
2 Serial ports
-
1.2M FDD
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-
40M 28mS HDD
2 Serial ports
1 Parallel port
1 Games port
On Board Real Time Clock
16 Bit 256K VGA card
VGA monitor
101 Keyboard
Full size tower case
220W power supply
-
DOS 4.01
-
-
-
On Board Real Time Clock
16 Bit 256K VGA card
VGA monitor
101 Keyboard
Mini tower case
-
200W power supply
-
-
DOS 4.01
-
-
-
-
$3200.00
Parallel port
Games port
On Board Real Time Clock
16 Bit 256K VGA card
VGA monitor
101 Keyboard
Full size tower case
220W power supply
DOS 4.01
1
-
1
-
$4150.00
-
-
$6950.00
ALL PRICES INCLUDE SALES TAX. TAX EXEMPT AND OEM P.O.A.
Freight The prices quoted are ex Store, cost of delivery and the risk of loss in transport fall upon the purchaser.
For the convenience of customers, delivery can be arranged through the supplier at the schedule of rates set out
below.
Minimum
Charge
ONLY
1.
Carrier, Melbourne & Metropolitan
2.
Carrier: Interstate
- $20
- $10
Only SMALL ITEMS will be sent by post
READER INFO NO. 34
For Features and
Shutter timer
Performance...
marks. The lens cannot 'see' the full distance around the circumference, so what one is measuring is actually the length
of a chord. Mark this chord on a full-size drawing of the
disc, then measure the angle between the centre and the
points of the chord and proceed as for disc A.
For slower shutter speeds, I geared down the electric
motor to run at 375rpm. At these speeds, 18° represents
1/125 sec. and 37° corresponds to 1/60 sec. With these discs,
there is a definite advantage in keeping the angles reasonably
small because, in doing so, any troublesome distortion is
minimised.
The procedures described measure total exposure time, the
same as an electronic instrument. Cameras used were 35mm,
6 x 6 and 6 x 0. Many were borrowed. I took three cameras
to be electronically tested and found close agreement with
my own results.
The width of the white lines is a consideration. For disc A,
deduct 0.7° from angle measurements taken at the circumference and for disc B, 0.6°.
An electronic timer is a very expensive instrument. My expenditure on the apparatus described here was less than $450
Gotta Gotta
r
GoidSicu
with
DM8135
Bargraph
rí1
I-
Wit large LCD display
r ' for relative measurements
I
nl
hold hroction
and Transistor testing
-
143.75
DM8243 with
Frequency Counter
Ultimate speaker leads
,1 ' ,qt. 4 rae LCD display
capacitance
Mick! frequency counter
+1d Transistor testing
Continued from page 51
$201.25
DM8433 with
Thermometer
1/2,dejit large LCD display
'SUM'S capacitance
sures Temperature -20 to +150
S2
ELECTRICAL
COMPONENTS
AT
PEAKER G
SIMUL
C
Fig.5: The author's proposed system for achieving NEGATIVE effective output resistance from the amplifier.
$166.75 *
ioid function
having ordinary positive output resistance.
This can only be explained by saying that, as seen by the
speaker feed points E -F, the system output resistance Ro is
in fact negative!
Would you believe that Ro could now be -7 ohms? That
mild negative value would make the series sum (Ro + R1)
equal to (-7 +8) = 1 ohm, leading to eight times heavier
damping factor than before.
romprct construction
Postscript
DM6335 fits
your shirt pocket
-
'
a '. LCD
>alay
n ,iy mode for relative measurements
a
Continued from page 25
$97.75*
Supported & Serviced Australia-wide
Elmeasco Instruments Pty Ltd
`1. 3J'P corm, d dp,
by
You've Gotta Getta Goldstar from
y.
_.
Ti-
:
A.C.T. John Pope Electrical 80 6576
N.S.W D.G.E. Systems (049) 691625
W.F.Dixon (049) 69 5177
Macelec
Newtek (042) 271620
(042) 291455
Novacastrian Electronic Supply (049) 621358
Obiat Pty Ltd 698 4776
Digitel 709 6511
Geoff Wood 4271676
N.TERRITORY J Blackwood (089 84 4255, 521788
Thew 8 McCann (089) 84 4999
B.A.S. Audiotronics 844 7566
QUEENSLAND St Lucia Electronics 252 7466
The Electronics Shop (075) 32 3632
(Townsville)(077)
Solex
72 4466
Xanthos
Electrical (079) 27 8952
S.AUSTRALIA Force Electronics (08) 212 5505
VICTORIA G.B. Telespares 328 4301
The Electronic Components Shop 670 6474
Factory Controls (052) 78 8222
Mektronics 587 3888
Truscott Electronics 723 3094
W AUSTRALIA Atkins Carlyle 481 1233
Leda Electronics 361 7821
PAPUA NEW GUINEA T E (P.N.G.) Pt Moresby 25 6322 Lae 42 6246
READER INFO NO. 35
Do you believe it? Has your incorrigible author been honest, fair-dinkum and entirely above board?
Peccavimus et benedicte! You be the judge. You might
even like to try building up the scheme shown in Fig.5, to try
it out for youself.
But now, please, let's not hear any more gumph about the
oxygen, arsenic and sulphur impurities in copper! Nor will I
tolerate bleatings bemoaning the conductivity loss due to
crystalline dislocations in copper, due to bending or dropping
wires and cables...
If you must worry about such miniscule reductions in copper conductivity, just use bigger cross section conductors!
Perhaps next time you'll want to do it digitally and use
fibre optic speaker cables. Happy listening!
WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR CHIPS ... WOOD FOR: C
0.
1000A Clamp Meter
Huge 52mm jaws
750Vac range
10 to 1000Aac
Analog Movement with stop
ST1000
$118.50
($102.70)
MULTIMETERS
Cr
Ó
o
O
o
EDM1133 Digital Multimeter
8 Autoranging Functions Vdc,
Vac, Adc, Aac, Ohms, Diode,
Continuity etc.
Analog Bar Graph
Range Hold
V
O
EDM1133
á
cc
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($148.80)
400A Clamp Meter
20A to 400A ac
750Vac
Peak Hold
DCT300
$126.95
3 3/4digits
EDM1155
$203.15
($175.10)
3/4 digit 4000 count resolution
Digital Display updates 4 times/s
87 has analog pointer, 83/85 have
4
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0.5Hz to 200kHz Counter with
duty cycle from 0.1% to 99.9%
10pF to 5pF Capacitance range
Input alert warning
87 is a true rms 1 ms Peak Min
Max hold with backlit display
Touch Hold and Relative modes
83
$478.80
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85
($480.00)
$576.00
87
$696.00
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Also...
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O..
EDM1177 Digital Multimeter
14 Functions including frequency
to 400kHz, capacitance to 40µF
etc
Peak Hold, Data Hold, Range
Hold
Analog Bar Graph
v
3 3/4digits
EDM1177
$248.80
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3487A
$144.00
($125.75)
L/C/R Meter
3 1/2 digit
Analog Multimeter
dB, L, C and R ranges
10A dc
2k[3/V sensitivity
1000Vac/dc
ST350
$31.20
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GP03020 DC Power Supply
2 by 30V/2A variable outputs
Fixed 5V/3A and 5V/1A outputs
GP03020
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$725.90
GPR3030 DC Power Supply
Single 30V/3A output
Fine/Coarse control
GPR3030
$280.50
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240V Variable Transformer
7A rating at O to 270Vac
4mm captive terminals
HSNO203
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240V Variable Transformer
5A rating at O to 250Vac
Sturdy steel case
HSNO103
$159.60
Probe Type Multimeter
3 1/2 digit 14mm LCD
Logic Tester
HDS90L
($53.85)
$59.95
Isolation Transformer
Fast acting 6A circuit breaker
Separate V and meters
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MA4803
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20MHz Readout Scope
Cursor measurements
5mV/div dc to 20MHz
2Ons to 0.5s/div
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GOS625
$806.40
40MHz 2 Channel Scope
5mV/div dc to 40MHz
2Ons/div to 0.5s/div Main
0.2ps to 0.5ms/div Delayed
C0S5041
$1372.50 ($1176.50)
10MHz Low Cost Scope
Compact, single channel
5mV/div dc to 10MHz
10ms/div to 0.1µs/div
($425.69)
G0S3310
$496.65
Iflliii
-50°C to +750°C
Fast response bead sensor
TM902C
$117.50
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35% accuracy
Detachable sensor
LX101
$103.50
/
Shooter EPROProgrammer
Standalone with LCD display
11MHz cpu
Programs CMOS 2716 to 27512
512k RAM buffer
32pin ZIF socket
RS232 port etc
Shooter
$962.50
($825.00)
LER123 EPROM Eraser
34x28pin capacity
Double element
Variable timer
LER123
$263.25
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OUV-T8T EPROM Eraser
5x8' slide out tray
Timer
15 EPROM capacity
20-30mins
OUV-T8T
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LER121 EPROM Eraser
Digital Thermometer
3 1/2 digit pocket size
($89.70)
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5000µW/s cm element
LER121
($90.80)
$105.30
Logic Probe
TTL CMOS, 24V compatible
17MHz max frequency
3Ons detection
Hi Lo, Pulse LEDs
E301
830.05
($26.15)
Logic Pulser
0.5 to 400pps
10µs width at 100mA load
Sync input
ELP810
($34.60)
$39.95
RF
60MHz 3 Channel Scope
a 5mV/div do to 60MHz
5ns/div to 0.5s/div A and B
COS50608
$1859.00 11593.90)
S
($138.30)
Lux Meter
3 ranges 2000lux to 50000lux
($27.00)
programmer
Simultaneously programs up to
4x32pin, 4EE/EPROMs, 4 PALS
1MB program in under 3minutes
Husky
$1092.00 ($936.00)
GP03030 DC Power Supply
2 by 30V/3A variable outputs
Fixed 5V/3A and 5V/1A outputs
GP03030
$743.40
($640.90)
I
Dissipation factors for L and C
200pF to 2000jF
20001 to 200H
20052 to 20Mí2
ELC130
($217.70)
$251.15
20MHz 2 Channel Scope
5mV/div dc to 20MHz
2Ons/div to 0.5s/div
C0S5020
($756.80)
$882.90
O
v,
0
3487A Autoranging DMM
3 3/4 digit
11 functions
Analog Bar graph
40kHz frequency counter
Relative measurements
Max/Min store
400A AC/DC Clamp Meter
3 1/2 digit LCD
8 functions including
temperature (K type input)
Peak hold Data hold
400A, 100Vdc/750Aac
DCT310
($159.20)
$183.70
U
rr
o
($109.50)
3486A Autoranging DMM
3 1/2 digit
8 functions
Data Hold
Auto power off
3486A
$91.10
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Series...
Top of
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$393.60
$180.00
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Husky EPROM Programmer
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Fluke 80
23
73
75
6 to 300Aac ranges
O to 600Vac
Fuse protection
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ST300
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$77.40
EDM1155 Digital Multimeter
12 Functions including
capacitance to 40jF
Peak Hold, Data Hold
Analog Bar Graph
Ó
o
$172.60
Illb
300A Clamp Meter
3 3/4digits
á
EPROM
PROGRAMMING
o
& AUDIO
2MHz Function Generator
Built-in counter and sweep
generator
AM and FM modulation
GFG8019G $619.60
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2MHz Function Generator
4digit LED frequency readout
GFG8020G $446.85
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1.3GHz Frequency Counter
5Hz to 1.3GHz
Switchable LPF and Attenuator
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20mV sensitivity to 100MHz
($674.00)
EFC2203
$773.90
RF
Generator
100kHz to 150MHz
100mV output to 35MHz
AM modulation, Counter output
($228.80)
GRG450
$264.00
Audio Generator
120MHz Frequency Counter
20mV sensitivity to 100MHz
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GFC80108 $300.10
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10Hz to 1MHz in 5 ranges
2OVpk-pk output <0.1% dtort
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GAG8088
$301.80
550MHz Frequency Counter
similar to GFC801OG
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GFC8055G $439.90
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GVT416
$266.00
Millivolt Meter
($231.70)
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INC IN NSW
229 Burns Bay Road, (Corner Beatrice St.)
Lane Cove West, N.S.W. P.O. Box 671, Lane Cove N.S.W. 2066
Telephone: (02) 428 4111 Fax: (02) 428 5198.
8.30am to 5.00pm Monday to Friday, 8.30am to 12 noon Saturday.
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READER INFO NO. 36
NEW PRODUCTS
20MHz mini portable
scope
ture and field coils, air-flow and over travel interlocks, are made via locking
connectors at a junction box conveniently located at the top of the shaker
body.
The body suspension employs an efficient system of pneumatic isolators, located above the centre of gravity at the
four corners of the shaker body.
For further information contact M.B.
& K.J. Davidson, 17 Roberna Street,
or
(03)
Moorabbin
3189
phone
Universal input
power supply
555 7277.
cuit protected.
The V209 20MHz mini portable oscilloscope by Hitachi is capable of operating from the mains supply of 12V DC
with 2 hours of continuous use from the
battery.
It is lightweight at only 5kg, and small
- 110 x 215 x 350mm, but with its compact design, performance doesn't suffer.
It has an easy to read 3.5" high luminescent high resolution CRT with internal graticule, lmV/div vertical sensitivity and 0.5us/div with x10 magnifier
to 5Ons/div timebase, 3% accuracy and
a risetime of 17.5ns.
The scope employs a TV sync separator with one touch synchronisation of
horizontal and vertical signals. It has
automatic focus control and trace rotation. The X -Y operation allows phase
measurement DC-200kHz (-3dB) with
3° phase up to 100kHz.
For further information contact IRH
Components, 32 Parramatta Road, Lid combe 2141 or phone (02) 648 5455.
Shakers for
product testing
The model B395/D395 shaker is a
low -profile,. wide -band, air cooled, electrodynamic shaker specifically designed
for high -reliability vertical testing, in
conjunction with CERT and products screening applications, e.g. MIL -STD -
781C and NAVMAT P-9492.
To achieve maximum energy efficiency, a double -sided magnetic field structure is used. Two copper field coils provide maximum gauss in the centre gap
for a high force -to -current ratio. All
electrical connections, including arma146
AIC
AMALGAMATED iNSTRUMEM CO
`
"=5Old
PRESSURE MPa
Multi -function pressure
monitor
The new Australian made PM2 panel
mount and TP2 weather proof series
pressure monitors from AIC have many
features, accepting an input from any
conventional strain gauge pressure
transducer. The units can function as a
pressure display, pressure controller,
signal conditioner, pressure alarm, liquid level display, signal lineariser, computer interface, transmitter and batch
controller.
A feature of the PM2 is the ability to
sense the voltage at the transducer and
compensate for the line voltage drop.
The excitation voltage and input sensitivity are link selectable.
The instrument has many keypad programmable functions including single or
two point calibration, set point relays
(can be set to various combinations of
high and low, n/o, n/c, hysteresis, delay
on/off, latching and internal alarm beeper, etc), decimal point position, extra
display zero digit and digital filter (for
noisy signals).
For further information contact Amalgamated Instruments, 7/21 Tepko Road,
Terrey Hills 2084 or phone (02)
450 1744.
ELECTRONICS Australia. August '1990
Power General has released a new
range of 65 watt switching power supplies that will operate from 85 - 265V
AC or 100 - 370V DC.
The auxiliary outputs come in a combination of triple or quad configurations
with zero % minimum load required on
all auxiliary outputs. The supplies are
overcurrent, overvoltage and short cirSix models provide outputs of +5V
DC along with combinations of -5,
5(Iso), +12 (Iso), -12 and +24V DC.
Efficiency is 65%, holdup time 16ms
and isolation is 5300V DC. Soft start,
overvoltage protection on +5V DC,
VDE/FCC class B onboard EMI filter
and current limiting are standard fea-
tures on all models.
The transient load capability of the
+12 and +24V DC outputs make up
the FLU3-65 and FLU4-65 series suitable for applications requiring pulsed
load capability, for electromechanical
devices such as disk drives and tape
back-up systems.
For further information contact Priority Electronics at 23-25 Melrose
Street, Sandringham 3191 or phone (03)
521 0266.
.1481;420
High performance
6.5 digit DMM
The Prema 6000 is a high performance 6.5 digital multimeter with Gohm
input resistance up to 2V and 100nV
resolution.
It offers seven functions, including
true RMS voltage and current measurements as well as 2 -wire and 4 -wire
resistance and 4 -wire temperature measurements. Temperature is measured
using PT -100 type thermocouples with
0.01°C resolution (range -200°C to
+850°C).
There is a choice of three integration
100ms, is and 10s. In addition,
times
an optional in-built 4 pole, 10 channel
scanner is available for the model 6000.
This is activated either from the front
panel of the model 6000 or remotely via
the IEEE 488 bus, and allows the user
to scan up to 10 different measuring
points.
High stability amplifiers and a precision analog to digital converter permits
uninterrupted averaging without disturbing breaks for continual automatic zero
correction, even with 100nV resolution,
which is achieved after only is integration time.
For further information, contact
Emona Instruments, 86 Parramatta
Road, Camperdown 2050 or phone (02)
Replacement
video heads
-
519 3933.
Membrane
switch systems
New Scotch membrane switch systems
use multiple layers of specialised adhesives to permanently bond, insulate and
separate circuit components and are extremely resilient. The adhesive is designed with very high shear strength, so
that it withstands the constant stress of
activation as well as harsh environ-
Surface mount
dry reed switch
The Clare Dyad is a hermetically
sealed dry reed switch. The laser sealing
process is performed in a nitrogen environment to enhance the life of the
switch. The contact area is characterised
by bifurcated blades that reduce the
bounce on operate. The flat blades of
the switch are made from a nickel -iron
alloy and exhibit high magnetic permeability.
The width of the blades and the ease
of formation make the Dyad well suited
for surface mounting. The Dyad has a
glass length of 15.24mm and 2.54 x
1.14mm width. The overall length.to the
extremities of the terminals is 19.56mm.
For further information contact IRH
Components, 32 Parramatta Road, Lid combe 2141 or phone (02) 748 4066.
and Hitachi.
Further information from Wagner
Electronics, 305 Live ool Road, Ash field 2131 or phone (02) 798 9233.
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ments.
Fast NiCad charger
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Mini solder bath
Every time a key is pressed, the flexible overlay of a membrane switch
'pulls' on the underlying adhesive while
making contact with the surface. The
adhesive bond in Scotch membrane
switch systems returns to place after
each `pull', and does not gradually seep
into the circuit, a problem which often
causes other circuits to fail.
The switches resist moisture, extreme
temperatures, ultraviolet radiation, and
solvents such as detergents, chemicals,
and household cleaners. Most importantly, the adhesive in Scotch membrane switches retains strong cohesion
over time, preventing components from
slipping as well as helping the product
to perform reliably year after year.
For further information contact 3M
Australia, 950 Pacific Highway, Pymble
or phone (02) 498 9333.
Sydney -based audio components specialist Wagner Electronics has released
the Dai-Ichi brand of VCR heads. The
Dai-Ichi brand is new in Australia, but
the Japanese factory is one of the main
manufacturers of video heads in the
world and has earned a repution for
quality. They are suppliers to many of
the major VCR manufacturers.
Wagner Electronics intends to make
the Dai-Ichi brand available as a lowcost replacement part for repairs to
VCRs. Dai-Ichi substitute video heads
are available for VCRs made by JVC,
Sharp, National, Akai, Sony, Toshiba
OK Industries has announced the release of the model MS -6060 mini solder
bath.
The MS -6060 is a simple, compact
and easy to operate mini solder bath designed ideally for tin processing applications. Its 300W heater enables rapid
heating of the 1.2Kg of solder carried
which, coupled with the K type thermocouple feedback loop, assures accurate
and stable control of the molten solder
temperature over the range of 200°C to
450°C.
This compact benchtop bath saves
space, while the heavy duty solder bath
construction ensures long life with high
heat resistance.
For further information contact Electronic Development Sales, 2a/11 Orion
Road, Lane Cove 2066 or phone (02)
418-6999.
Eveready Australia has developed a
one hour Fastcharge nickel -cadmium
battery system which reduces battery recharging time from 14 hours to one
hour.
The system consists of a one hour
charger and power pack, plus AA size
rechargeable batteries in blister packs of
two or four. The batteries are designed
to take the high current associated with
one hour charging.
The charger is matched to the characteristics of the batteries so that one to
four batteries can be fully charged
within one hour, safely and without
damage.
A special detection system allows the
charger to adjust to a Fastcharge battery and charge it in one hour. Similarly, it will detect ordinary NiCads and
charge them in 14 hours. An interlocking cover prevents the unit from operating unless the cover is properly closed.
The design of the charger will not
permit the accidental reversal of batteries a common cause of the destruction and potential explosion of batteries
in other units.
For further information contact Eveready Australia, 30-40 Harcourt Parade,
Rosebery 2018 or phone (02) 667 0444.
-
ELECTRONICS Australia, August 1990
147
ZEW PRODUCTS
ing, and with a smooth finish for silk
screening.
Retail price of the new cases is
$39.95, but Altronics can also offer an
attractive quantity discount price for
OEMs.
Further details from Altronic Distributors, 174 Roe Street, Perth WA 6000
or phone (09) 328 1599.
MIDI controllers,
interfaces
`Super large'
instrument cases
Altronics has released a new 'super
large' range of Australian -made instrument cases, moulded in tough shockresistant ABS plastic. Similar in basic
design to the company's very popular
H-0480/1 and H-0482/3 cases, the new
H-0490/1/2 cases measure 355 x 250 x
122mm
large enough to house higher
power inverters, amplifiers, power supplies, microcomputer systems and in-
-
struments.
Like the smaller cases, the new cases
employ a four-part construction, with
moulded upper and lower sections and
removeable front and rear panels. An
array of internal mounting pillars are
provided to support transformers and
other heavy components, as well as for
PCB mounting, etc. Both upper and
lower case sections are provided with
many ventilation slots for air -flow cooling.
The new cases are available in three
colours: grey (H-0490), black (H-0491)
and blue (H-0492). The ABS front and
rear panels are designed for easy punch -
The Fadermaster MIDI command
controller features include eight programmable MIDI faders; scan speed,
range, grouping and MIDI channel are
selectable per fader; lithium battery
backed RAM memory; 10 user programs; 30 factory presets, MIDI in and
out with programmable Echo through;
bright readable LED display.
The Nexus Plus two input by eight
output MIDI patch bay features selectable merging, transposition and zoning
(four overlapping zones can be programmed), plus channel filtering and
auto thinning of MIDI controller data.
f//
1".
1
1
1
There's also a panic button, battery
backed memory and toggle switches to
select MIDI input A, B or merged inputs.
The MacNexus MIDI interface for
ELECTRONIC
PROJECTS
TOOLS
DATA BOOKS
TEST EQUIPMENT
TV ANTENNAS
SEMICONDUCTORS
EA & T/E PROJECTS
WE DO IT BEST IN THE
SUNSHINE STATE
DAVID HALL
ELECTRONICS
3/376 KINGSTON RD,
SLACKS CREEK 4127
Ph (071808 2777
Fax (on 209 2623
READER INFO NO. 37
148
1
ELECTRONICS Australia, August 1990
PCB ARTWORK A PROBLEM?
DO YOU HAVE SCHEMATICS THAT
NEED TO BE DRAWN OR UPDATED?
IF SO CONTACT
CIRCUITWORKS
*
*
*
*
*
ALL TYPES OF ANALOGUE & DIGITAL
BOARDS.
GENERAL ELECTRONIC DRAFTING.
.
WE CATER FOR THE HOME HOBBYISTS &
PROFESSIONAL WORK CENTRES.
CIRCUIT BOARD PRODUCTION IF
REQUIRED.
PROMPT SERVICE.
PHONE: (07) 3591285
65 EVANS STREET, KEDRON, OLD.
READER INFO NO. 38
(03) 560 9111.
Automated audio
measurements
Qrjr r,u,u
1
Macintosh features on Macintosh serial
port connector, one MIDI input and
three MIDI outputs and activity LED's.
The serial port connector plus into
Mac's printer or modem port.
Synapse is a fully programmable 16
input by 20 output MIDI switcher and
processor. It features three independent
programmable MIDI processors, each
with channel filtering, channel bumping,
data filtering to selectively remove
notes, controllers, pitch bend, program
change, after touch, system exclusive
and system common message.
For further information contact
Tradepower International, 29A Glen vale Crescent, Mulgrave 3170 or phone
The Tektronix VM700A option 40
audio measurement set can totally
characterise an audio path in under 35
seconds with no interruption of video
measurements in progress. The Tektronix ASG-100 audio signal generator
produces the tone sequences used by
option 40 for measuring to CCITT 0.33,
ANSI T1.502-1988 or EIA/TIA-250-C
standards.
Automated measurement results are
presented in an easy to read tabular format that is identical to the VM700A's
familiar auto mode video measurements. All the convenience of remote
logging, timed reports and user set
alarm limits are retained for audio
measurements as well.
Option 40 utilises an FFT (fast fourier
transform) to provide a real-time dual channel spectral display of audio frequencies. This display includes a readout for signal-to-noise ratio. And with
the aid of a cursor, the signal level at a
specific frequency can be measured.
The option 40's audio analyser mode
allows manual measurements of frequency response, THD+N, phase and
level difference between channels and
crosstalk for both channels.
For further information contact Tektronix Australia, 80 Waterloo Road,
North Ryde 2113 or phone (02)
888 7066.
When you need
Constant Power
Setec's the
Answer.
`Obsolete' personal computers
Continued from page 60
things like logs and square roots. So they have all kinds of
possibilities for electronic calculations (See my article in EA
for November, 1989).
You can pay heaps of money for a computer spreadsheet,
and like word processors they can become very bloated
memory hogs. But, as usual, there is an alternative: Supercalc. Again it comes in both CP/M and IBM versions. I use
Version 2 with CP/M and Version 3 with IBM. Supercalc is
now into Version 5 and is being actively marketed for the
PC. And yes, there are Shareware versions such as PC-Cale.
(Editor's Note: Sorry to interrupt, Tom, but there's also Microsoft's original spreadsheet, Multiplan Version 1. It too was
sold in both CPIM and MS-DOS versions, again virtually
identical and quite powerful enough for most purposes. 1 still
process all of EA's contributions payments, and print cost
estimates on Multiplan Version 2, which is only slightly fancier...)
Circuit board design is the one process that demands
graphics, so CP/M is out, unfortunately. But, despite what
you may be told by the computer professionals, you don't
need a really flashy PC to do PCB design. The humble 'colour graphics adapter' format is fine, even without a colour
monitor. I've been using a package called `Protel Easytrax'
(reviewed in EA December, 1989) with a simple amber screen video monitor hooked up to the CGA connection,
and it works fine.
as
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Where are they?
Look at the ads! IBM computers come in two basic types,
XT and AT. AT stands for `advanced technology' and you're
expected to pay big bucks for it. But the XT is no longer
trendy, so you can expect to find brand new ones for under
$1000. Used XT systems, tossed aside for the more desirable
AT's, can be picked up, monitor and all, for less than $800.
There are a lot of used CP/M computers about, but you
don't seem to see them advertised much. I think many owners are suddenly realising how useful CP/M machines are,
and they're hanging onto them. But they still come up, usually from businesses that are finally moving up to IBM -PC's.
If you're lucky you can score a Kaypro or Osborne Executive (semi -portable computers), for 10 to 20% of their original cost. And most will come with software included. You
may even get the computer with WordStar, Cardbox, and
Supercalc, all in one hit!
Shareware software can be obtained in one of two ways.
There are companies in Australia that specialise in Shareware; they usually sell the stuff for around $10-15 a diskful.
These are trial versions of the software; if you end up
using it you are expected to send a fee to the software author who then sends you the complete version. This could be
around $30-50 for a word processor, but it's still very cheap
compared with the commercial stuff. Shareware is also distributed through the many computer bulletin boards around
the country. You ring them up and then use your modem to
download the programs onto your own disks. Once again
you're expected to pay the author if you actually use the
software.
Most of the information this month has pertained to home
and small business uses of computers. Next time we'll concentrate on the pure electronics side of things, and find out
how old machines such as Microbees, Commodore 32's and
64's, and Apple II's can be useful in an electronics workshop.
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The BCE I provides 13.65 volts at 10 amps (BCE2: 27.6V, 5A)and have
been designed specifically for telecommunications applications
demanding high reliability under heavy usage, low noise, fully
automatic and unattended operation and full protection features.
The BCEI and BCE2, have three main applications:
As lead acid battery eliminators they may be used to power
equipment that normally runs on a 12V (BCE2: 24V) batteries.
As lead acid battery chargers they will provide a safe and
convenient method to restore discharged batteries.
Fully charged batteries may be left connected to the unit
indefinitely with no adverse effect on their lifetime.
The full features of the unit are realised when both a battery and a
load are connected so that it operates as a power supply with
power fail protection.
When a mains failure occurs the power supply no longer provides
power. The battery remains switched in parallel with the load and
supports it without interruption.
During extended mains failures the unit disconnects the battery
before it becomes excessively discharged. The battery is
automatically reconnected when mains is restored and very
quickly assumes a workable voltage.
II
1
/'11
.1
SETEC
The high powered performer
SETEC PTY. LTD. 6 HOLLOWAY DRIVE. BAYSWATER 3153
PH: (03) 762 5777, FAX: (03) 762 9197
MAWR
INFO NO
39
GREAT SAVINGS GREAT SAVINGS GREAT SAVINGS
You get more for your dollar
with Rod Irvin ci Electronics!
-'
el
II
CENTRONICS
CONNECTORS
14 Way plug
24 Way plug
36 Way Plug
k
1-9
10.99 100.
P10514 52.50 52.25 51.50
151114
m open
Range: Over 300 feet
....P12210
Pose.r ou is: 9V Bandy
Type Eleclrel Condenser
DImenSlona: 185 27 a 38mm
Weight 160 grams
10.
1004
$2.50
52.00
Cat. A10450
..
$24.95
SOLDER CENTRONICS
IN -LINE SOCKET
104
$4.50
$4.95
SOCKET
1-9
10-99 100.
P10516 52.50 52.25 $1.50
BNC CRIMP PLUG
MASTER
RACK MOUNTING
1-9
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1,9
These Superb rackNETmou Caanets
wan give your protects a real
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Just l00k at these features
All dimensions conform to the
51.95
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e,rioueahle lop and
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Ventilated Id
Horizontal Depth: 254mm
16 Pin
P13101
Deluxe brush hoist' anodised from
A
SOLDEALESS
TWIST ON PLUG
P12102
$1.95
$1.75
51.95
$1.75
26 Pin
P12103
88
132
44
88
132
57 82Nalural1110402569.50
89 126 Natural H10403 579.50
34 38 Black 11,0411 565 O0
57 8280ck 1110412 575.00
89 126 Black H10413 545.00
34,PIn
P12104
1.9
$1.90
$2.00
$3.00
10+
100+
$0.55
$0.50
S11060 $0.60
$2.50
-
S11070 $0.70
$3.25
$3.50
D TYPE IDC PLUGS
10.
1.9
1004
DE9P º pin plug
P12166 $2.95 $2.50 52.00
DA15P 15 pin plug
P12168 $3.50 $3.00 $2.50
0B25P 25 pin plug
P12170 53.95. $3.50 $2.95
OPposd,on S'
6040 Resin cored
Descrmpl ron
Cat.No
T31000 71mm2509rn
731002 71mm5004m
131010 91 mm 250gm
13,0,2 9rmm sown
T31020 6mm 7501Ir'
731022 r 6mm SOOgm
731030 71mm I metre
t3r032 91mm I metre
731034 r 6mm men*
1
1
Price
$8.95
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57.95
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Thew duel .I wise nl bemire indeed
detector* .n wry r11.14. way 1.
very
protctlon when
TYPE IDC SOCKETS
DE9S
9
pin socket
10.
1-9
1004
1s pin socket
DAi56
P12169 $3.50 $3.00 $2.50
25 pin
08255
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pare) They Meted maid thing.. In
rmprm .NCh 1.mrrvrted by M
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P12167 $2.95 $2.50 $2.00
compact Mfg*
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co0ounmt
hue
elder
neng.
wall or can«
Norm.ny 414.40 relay, temper
ouput end LEO 056 kWlc.1,.
Opr.bng voiug: 10.14VDC
Current bee: 20nA
sadist
TEXTOOL IC
SOCKETS
(ZERO INSERTION
FORCE)
Thous ZIP
.0á5b
100
10+
P10966 $5.95 $5.50 $4.00
I
\
16pin
P17016 $16.95 $13.95
24pin
Plug
40pin
P17040 $34.95 $32.95
$3:00 $2.95
Socket
P12201
10.
$3.95 '$3.00
100.
$2.95
10dB IN -LINE COAXIAL
Galin
Prorcb c.nl*.or. a Nllwa/..
Lovers eI .ne 25e0 . om
$69.95
computer backup power ippOf ,deal
for many pow, need
574.95
$64 95
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564.95
574,95
S PlugUIOUTm álugRD
Replacement hand set COrd
Length 4 5 metres
Cat. Y16023
$7.95
$19.95
k
EPRO.M.RASER
ELI
ate row
s 0mckly brand
Safely This unit is tris COST enecbee
soluhOn to your problems II will
erase up to º 24 pis devices in
arnoete satery on about 40 nwlules
less to less chips)
ealurns ,octane
Chip di :Won has Conducevp roam
pad
Mains (K.wanA
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H,gn UV rinens,ty al Chip SWIM!
entones EPROM. are Thoroughly
erased
Engineered to prevent UV
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Sperm
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73
m.
$149
ROD IRVING
ELECTRONICS
co
Z
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SYDNEY:74 Panamana Rd.
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Phone: (02) 519 3134
Z
MELBOURNE: 48 A'Becketl SI,
Phone: (03) 663 6151
ai
C_
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Phone: (03) 489 8866
HEATSINK!
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Descnplpn
100
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814710
R14720
R14730
AR
$3 50
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SOR
53 20
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RI4740
70012
$350
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R14750
5000
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IM
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814770
814780
814790
R14800
814810
R14820
814830
814840
814850
POOR
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5320
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1.11.1
INSULATION
DISPLACEMENT
(TYPE
bond,
Cuts CR RHam ..grtal, inrenerea e
Cal 111048
$5.95
4r4c.vw
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4
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al
Cap foal his end
hand plus o.e, IOC Cable
61
Cat No
Oescr,plion
1'17tI1,
'lip.,'
tap.n
P17174 14pal
017140 a0 pe
1.9
10
5150
51.40
51.50
$2.75
55.75
51 60
5295
55 95
Fr,
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AT
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MAIL ORDER 6
CORRESPONDENCE:
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Order Hotline: 008 33 5757
(Toe tree, strictly orders only)
POSTAGE RATES
S1-$9.99
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The weave postage tales are for
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Phone: (031 543 7877
Fn: (03) 543 2648
5100-5199
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look
Power Requirements. 17V A C
Adaptor !included)
Input Impedance' 75 ohm
Output Impedance: 75 ohm
Cal L15043
$39.95
Cam X
F
564.95
$74 95
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Cat $15029 12V 1 2 AH
Cat $15031 12V 2 6 A4
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7815UC
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VCRs AC adapto .riuded
SPECIFICATIONS'
Frequency Range. 5 900MHz
100.
$64 95
300
TELECOMMUNICATION
P17028 $26.95 $24.95
Reduces loss roan 5pl,ners and bng
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antennas coaxial leed lines and
P12200
104
1-9
300mm 110 sheds,
600mm 15 sneelsl
6015 BLACKMIHITE
250. 300mm 110 sneelsl
300 . 600mm 15 sneer)
8016 BLUE WHITE
250 30600,110 sneelsl
300 600mm 15 sneers)
8018 GREEN WHITE
250 . 300~0 110 shee:si
300 600.nm 15 sheets)
250
X 15663 Male to Male
15661 Male to Female
Gal 01'5664 Female to Female
Cat
t al X1.955
28 pin
nom^d sized rooms
sr. I2m 12m
IDC CENTRONICS 36
WAY PLUG 8 SOCKET
PHOTOSENSITIVE
(EX SCOTCHCAL)
All prices per box and Include tae
8007 REVERSAL FILM
250 300mm 110 sneelsi
$39.95
300 600mm IS sheerst
$54.95
8005 BLACK ALUMINIUM
750 300mm 110 sheets,
$69.95
300 600mm 15 sneers)
579.95
8009 BLUE ALUMINIUM
569.95
250 300mm 110 sneelsl
300 600mm 15 sneelsl
579.95
8011 REDWHITE
250 . 300mm I r0 sheelsl
564.95
300 600mm IS sheers)
074.95
9013 BLACK/OELLOW
WITH BUILT-IN TIMER
P/7024 $19.95 $18.50
I
r
$69.95
Proor
c
Femaleio-`eerale
Saves modrlytng or :eplac'ng
non-maling Centronics cables
All 36 p.ns wired straight Through
3M DYNAMARK
WITHOUT TIMER
(,n .14950
$119
are
perfect for Inserting end
'nimoving EPROMS so
es not to damage the
IC pins.
1.9
10.
P12171 $3.95 $3.50 $2.95
1.9
1-9
3
RECHARGEABLE 12V
G LL BATTEEIE S
linrtat
o
long roc. If.
MOW mw
catbw 0lá 4.0 tOr bur¢iw
ameeme. amrg cy Wong or we
PASSIVE INFA-RED
DETECTORS
rd
CENTRONICSM GENDER
RS
$0.60 $0.50
bsOdTely topRgOui,l ry
$3.95
CANNON TYPE
PIN CHASSIS
FEMALE
push on
P12108
D
P10964 $4.50 $4.20 $3.20
push on
36 Pin
P12106
MINI
MOMENTARY
PUSH BUTTONS
$8.95
1-9
10+ 100+
P10962 $3.95 $3.50 52.90
10-99 100.
1-9
P10531 52.50 52.25 52.00
B
RS232 GENDER
CHANGERS
Saves mobhyrig or reporting
non-mating 05232 Cables
An 75 pins wired straight through
Cal X15650 Male to Male
Cal X15651 Mal* lo Female
Cal X15652 Female le Female
3
Etemal Front Panel He,9hlmm
Mounting Hole Centres mm
Internal Chassis Height mm
FInleh Cat.No. Price
C
44 34 38Nalural1110401559.50
A
CANNON TYPE
PIN CHASSIS
MALE
CANNON TYPE 3
PIN LINE FEMALE
10+ 100
1-9
B
C
20 Pin
100
10-99 ION
BNC
International Standard
All aluminium construc:oOn
Choice of black or natural hniSh
141
10 Pin
Description
Price
Holes
$ 2.75
640 Holes
$10.75
640. 100 Holes $14.95
640 200 Holes $17.50
P1lo/0 1280. 100 Hobs $26.95
P11011 1280 300 Holes $32.50
P11012 1280 too Holes $39.95
O 11015 1920
500 Holes $59.95
P11018 2560. 700 Hobs 569.95
P11000
P11005
P11007
P11009
P10530 52.95 52.75 52.00
S
IDC SOCKETS
BREADBOARDS
Cat. No.
-
BNC PANEL
P12211
1.9
$3.90 $3.00
held
,,..P12701
owFM
.Nton:
Sr:
CANNON TYPE 3
PIN LINE MALE
1.9
10+ 100
P10960 54.75
M5JO PH ONE
....P12205
52.95
40 Pin
11
BNC MALE PLUG
OMNI-DIRECTIONAL
1-9
36 Way
j4
basic postage only Road Freighl.
bulky and Iragde dents will be
charged at dierent rates
All Isles las ampt orders And
wholesale endow.* to
RITRONICS WHOLESALE.
56 Renver Rd. Clayton
Ph (03) 543 2166 (3 Irnos)
C-
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RGAINS BARGAINS BARGAINS BARGAINS BARGAINS
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088 335757 TOLL FREE MAIL ORDER HOTLINE FOR CREDIT CARD ORDERS!
P11°9
SAVE SAVE SAVE SAVE
NEW CRO'S
.1_tt=11
-'
INSIDE THE IBM PC
PCB MOUNTING
SCREW TERMINALS
(INTERLOCKING ENDS)
These terminals feature
Interlocking ends to form any
number of connections.
Standard 5mm spacing pins.
P10520
2
1-9
í!9
EA
1
820080
1
$44.95
100+
$0.70
!19F,7
_
METEX M-3650
MULTIMETER
20MHZ DUAL TRACE OSCILLOSCOPE
CRT DISPLAY
150mm rectangular
20A, ash digit frequency
VERTICAL DEFLECTION
Deflection Factor: 5mV to 20V/ Div on 12 ranges in 1-2-5 step with
fine control
Bandwidth DC: DC to 20MHz (-3dB)
AC: 10Hz to 20MHz (-3d 8)
Operating Modes: CH -A. CH-B, DUAL and ADD (ALT CHOP L202 only)
Chop Frequency: 200KHz Approx.
way
10+
$0.75
(Revised and expanded edition)
-Peter Norton
The widely acclaimed guide to the
IBM PC sinner workings The latest
edition now covers every model of
the IBM micro PC XT and AT and
every version 01 DOS from
to 3 0
91.
$0.60
Channel Separation: Better than 60dB at 1KHz
way
$0.90
P10521
3
<A $1.00
.
12V DC FANS
$0.80
80 a 80 a 25.4mm
12V DC, 1.7 Watt, 0.14 Amps
T12469
$12.95
10+ fans only $11.95 each
49
Eft
4A
MICE
RECTANGULAR
LEDS
1-9 10.99
RED
20c 15c
GREEN
20c 1Sc
YELLOW 20c 15c
ORANGE 20c 15c
í2c
12C
QUICK MOUSE
Gold machined pins
Extremely high quality
Anti-wicking
ideal for professional use or
where field service
components Is required.
Cat.no. Description 1-9
10.
P10620 8 pin
$1.20 $1.10
P10624 14 pin
$1.60 $1.40
P10626
P10628
P10630
P10632
P10634
P10640
P10644
16
18
20
22
24
28
40
pin
pin
pin
pin
pin
pin
pin
l
11-11-1-11-
.
t
U
$1.90
$2.00
$2.20
$2.40
$2.60 $2.40
$2.90 $2.70
$2.95 $2.75
.
small fortune on these
"Direct import" low profile Ic
sockets! PCB mounting solder
tail. All tin plated phosphor
bronze or berryilium and dual
wipe for reliability.
a
8
pin
14 pin
16 pin
18 pin
20 pin
22 pin
24 pin
28 pin
40 pin
$0.20
$0.25
$0.25
$0.40
$0.40
$0.40
$0.40
$0.50
$0.50
X19952
1
1
53950
OTHER SPECIFICATIONS
Weight: 7Kg Approx
Dimensions: 162(H) a 294(W)
x
_.______
Built in tilling bail
Capacitance meter
lnstrucl.On manual
FREE
100 PAGE
CATALOGUE
PLEASE CALL
IN AND PICK
ONE UP
$750
.
C.71
41
te
I
F
.
$59
40MHZ READ-OUT OSCILLOSCOPE
FLASHING LEADS
1-10
10+
$1.10
$1.00
sr I^),
a I-
.
r
ti
r= f _rte
METEX 3530
MULTIMETER
CRT DISPLAY
150mm rectangular
Compact. rugged. battery operated.
VERTICAL AMPLIFIER (CH1 and CH2 Identical)
Operational Modes: CHI, CH2, ADD, DUAL. ALT, CHOP
Sensitivity: 5mV-5V1 Div 3% in 1-2-5 steps
1mV-1V/ Div x5% x5MAG
Bandwidth DC: DC to 40MHz (-3dB)
AC: 5Hz to 40MHz (-3dB)
Rise Time: Less than 8.7nS
hand held 31/2 digit multlmeter
Features...
sit- high contrast LCD
Automatic over -range indication
with the "1- displayed
Automatic polarity indication on
DC ranges
Capacitance measurements to
E. Aadout Onotar
HORIZONTAL AMPLIFIER
Operating Modes: X -Y operation CHI -X axis, CH2-Y axis
Sensitivity: 5mV-5V/ Divt 3% in 1-2-5 steps
t0
t
Hz
o1
(-3dB) 3%
AC: 5Hz to 1MM: (-3dB1
Bandwidth DC: DC
1:3l' 22
GP0 P
e2 0hbGat)et-
Sweep Method: AUTO NORM, SINGLE
Sweep Time (A): 0.2ps-0.5S/ Div±3% in 1-2-5 steps (X1 only)
Red, 5mm
(B): OAS-0.SmS/ Div+3%kí 1-2-5 steps (XI only)
Magnified Sweep: 10 times+5%, Max 2Ons
Linearity: ±3% or better
012107
20uF
Diode testing with mA fixed
current
Audible Continuity Test
Transistor hFE Test
SPECIFICATIONS
Maximum Display: 1999 counts
31/2 digit type with automatic
polarity indication
Indication Method: LCO display
1
Measuring Method: Dual -slope in
A -D convener system
Over -range indication: "I" Figure
only in the display.
Temperature Ranges: Operating
Power Supply: one 9 volt battery
(006P or FC- I type 01 equivalent)
Normally $139
Cat 091540
$1,695
SPECIAL
$99
ííA
-s+$ $ $ $ $ $ $ $ $
$. $ $ $ $ Í siw/w/' l ti
r
m
m
VL?L T_
w
_a
TIME BASE
1111
ci
.
WITTY MOUSE
space and less hand
movement required
Optical rotary encoder
Max. tracking speed: 200m/sec
Mouse resident firmware
Size: 116 a 66x 34mm
Mouse Driver Software
included, allowing you to
install with all popular software
packages. Also included is the
handy Pop-up menu software
that allows the user to
integrate the mouse with the
keyboard, DOS, and other
Normally $165
Special, only 5129
lan
Three buttons, user definable
Silicone coated steel ball
High resolution movement of
Z10159
iº
20 Amp
352(D) mm
012105
If,
frequency counter (to 200Htl
diode and Iransistpr lest continuity
lwdhbu/rerl capacitance meter up
top amp current measurement and
comprehens,e AC DC voltage
current and resistance ranges
CHECK THESE FEATURES..
Push button ON OFF setter,
Aud,be continuity test
Swgle IWCign X pos,on easy to
use rotary switch for FUNCTION
and RANGE selection
TranslsTa lest
Diode test
Ouasty probes
High comas? LCU
Full overload protection
a
091550.
HORIZONTAL DEFLECTION
Deflection factor. 5mV to 20V1 Div on 12 ranges in 1-2-5 step with
line control
Frequency Response: DC to MHz (-3dB)
Max input Voltage: 300V DC
AC Peak of 600Vp-p
X -Y Operation: X -Y mode is selected by SWEEP TIME/ Div switch
Intensity Modulation Z Axis: TTL Level (3Vp-p-50V) bright, - dark
1:tvoi
X19950
$0.18
$0.20
$0.20
$0.35
$0.35
$0.30
$0.30
$0.40
$0.40
each
Div or more
Vp-p or more
This spectacular rugged and
eompael DMM has a blight yellow
high impact basic case IT features
$79.00
popular software packages
1-9
10.
P10550
P10560
P10565
P10567
P10568
P10569
P10570
P10572
P10575
MICROSOFT' COMPATIBLE!
Auto -selection and auto transfer between mouse
system system PC mouse
mode and Microsoft serial
mouse mode
Microsoft Serial Mouse and
Mouse System compatible
Super high tracking speed:
600mm/sec
Super high resolution:
200 D.P.I. (0.12mm/dot)
Silicon rubber coated ball
Optical rotary encoder
195 dots/inch. Smaller table
l l l l
Cat. No. Description
pro° t° s°1 220.
$1.80
$1.90
$2.00
$2.20
LOW PROFILE IC
SOCKETS
Save
Sweep Time: 0.2p Sec to 0.5 Sec/ Div on 20 ranges in 1-2-5 step
with fine control and X -Y
Magnifier: X5 at all ranges
Source: INT, CH -B, LINE or EXT
Triggering Level: Positive and Negative, continuously variable
level; Pull for Auto
Sync: AC, HF Re), TV (each or -) at TV Sync. TV -H (line) and TV -V
(Frame) sync. are switched automatically by SWEEP TIME/Div switch.
12c
12c
GOLD INSERT LOW
PROFILE IC SOCKETS
Type: Automatic and normal triggered in automatic mode, sweep is
obtained without input signal
TRIGGERING
Sensitivity Int:
Eat:
100.
1
TIME BASE
counter multlmeter with
capacitance meter and
transistor tester.
ai'iiT~ll
aT$S
I5711.LTY11
ir:fÍ:
$ $ $ $ $ $ $ $ $
O
2
n
Loop aerials
-
a type of aerial that has had periods of limited
The first ever receiving aerial was a loop
band reception.
broadcast
dominate
its
descendants
Today
popularity.
The German physicist Heinrich Hertz
generally credited with putting the
science of electromagnetic radiations on
a firm footing. During the years 188688, he conducted a series of experiments to confirm the existence of the
phenomena that had been predicted in
1864 by the Scottish mathematician
James Clerk Maxwell. Many of Hertz's
experiments were conducted in what is
now known as the VHF band, and the
receiver he most frequently used incorporated a directly excited single-turn
tuned circuit that was in fact, a loop
aerial.
With his loop, Hertz was able to
prove that electromagnetic waves behaved like light in that they could be directed, reflected and refracted. He also
observed that the orientation of the
loop affected the intensity of the received signal.
Since then, loops have come in many
different shapes and sizes. Generally
multi turn, it is today most used at
is
Fig.1: Hertz's receiver. This diagram
from a 1906 book shows how the
loop included a microscopic spark
gap which discharged on receiving a
signal. It has been estimated that at
least 300 volts would have been
necessary to create a visible spark.
But with this elementary and
insensitive equipment; Hertz was able
to prove Maxwell's predictions of the
behaviour of radio waves.
152
medium and low frequencies.
Wound on a cruciform wooden frame
as either a flat spiral or as a box, the
loop aerial became one of radio's early
symbols. To be domestically acceptable,
some were made to be folded for easy
storage. Today, use of the loop in its
modern form as the ferrite rod antenna
is almost universal.
How loops work
As there is a detailed analysis of loop
operation in just about every book on
radio fundamentals, this description will
be brief.
The electromagnetic component of a
passing radio wavefront generates voltages in the vertical portions of the loop,
but nothing in the horizontal sections. If
the vertical legs are in the plane of the
radio wave, there will be equal voltages
generated in each. These will cancel and
the net result at the terminals will be
nil, accounting for the well known nulling and direction finding properties of
the loop.
If the loop is turned through 90", the
vertical legs are now spaced through the
line of the cyclically moving wavefront.
The induced voltages will no longer be
equal, but there will be a small difference voltage which is dependent on the
distance between the legs, their length,
and the number of turns. This difference voltage becomes the useful output
of the loop.
Provided that there are no re-entrant
components, the shape of the loop is
unimportant and it can be rectangular,
square, triangular or even circular. Output is proportional to area and significantly, height above the ground is unimportant.
Early uses
During the last decade of the 19th
century, workable systems of wireless
telegraphy evolved. Increased transmission range was a prime requirement,
and, following Marconi's discovery that
ELECTRONICS Australia. August 1990
:-
i'
-
gm.
.
i
_
..
x,
r
Homebuilt box loop and
superheterodyne receiver from the
late 1920's. The loop is centre
tapped, to enable regeneration to be
applied to the RF amplifier valve.
Many
early superhets
used a
self-oscillating mixer coupled to the
aerial.
elevated wires improved signal strengths
considerably, development concentrated
on large open aerials. Prior to the availability of the high vacuum triode valve,
there was no way of amplifying received
signals, and the big Marconi aerial was
essential to extract sufficient energy for
reasonable reception. Loop aerials were
far too inefficient for practical communications.
Nevertheless, during 1905, H.J.
Round of the Marconi Company investigated the direction -finding properties of
loop or frame aerials. This characteristic
had important implications for marine
radio location, and the outbreak of the
1914-1918 war stimulated further re Flg.2:
search. The high vacuum triode valve
had recently become available, and RF
amplification of loop signals, although
somewhat inefficient, was possible.
Loops in WW1
Honouring H.J. Round in an address
to the Radio Club of America in 1952,
Edwin Armstrong
of superhet and
FM fame
related how his friend Captain Round had by 1916, developed a
stable RF amplifier with no less than 19
stages of amplification! This was used in
conjunction with a direction finding
loop to eavesdrop on the German Navy,
safe at anchor in Willemshaven, 300
-
-
miles away. The unsuspecting Germans
actually used plain language for their
traffic, not imagining that they were
being monitored.
Armstrong quoted from the memoirs
of the First Sea Lord, Admiral Sir
Henry Jackson, who was himself a naval
radio pioneer. Jackson wrote how one
day Round's direction -finding equipment had indicated that the source of
the signals from one of the German
ships had changed position about 1.5°.
This alerted the British Admiralty to
the possibility that the Germans were
putting to sea, and the order was given
to the Royal Navy's Grand Fleet to intercept them. The German fleet was located and the outcome on the 31st May
1916 was the great Battle of Jutland.
Already, the loop aerial was a vital
piece of equipment in marine radio.
During the early post war period, the
prime application of the loop was as a
direction-finding aid. It is useless as a
transmitting aerial and its low efficiency
meant that there was little incentive to
use it as a receiving aerial for normal
communication work. It was no match
for the large wire aerials that were readily erected on ships and at land stations.
With the development of broadcasting
in the early 1920's, the emphasis was
still on aerial efficiency. At first, transmitters were low powered and receivers
insensitive. In the United States, as in
Australasia, listeners were frequently
long distances from transmitters, many
of which were low powered. Large aerials, today erroneously called 9ongwire',
were essential and forests of poles
sprouted in back yards.
Britain different
In England, the situation by the late
was somewhat different. The
country had good coverage from a network of high powered transmitters, and
although many listeners could only afford crystal sets which did need large
aerials, loops could often provide ade1920's
quate reception with multi -valve radios.
Many listeners preferred their radios
to be movable. In his book Radio
Radio, Johnathan Hill claims that
around 1926, portables had a leading
share of the British market. It was common for these receivers to have a loop
aerial either in the lid or wound around
the inside the cabinet. During most of
the year, they were used as domestic receivers, but could be taken outdoors if
and when the weather permitted.
Here, and in America, portable receivers had not been anywhere near as
common as in Britain. However, prior
to 1930, many of the early superheterodynes did use loop aerials. A major reason was that they frequently used a selfoscillating mixer valve, which could
radiate a considerable amount of interference if coupled to a large aerial.
Early New Zealand radio regulations
actually required superheterodyne receivers to use loop aerials!
The early RCA superhets were often
supplied with ornate loop aerials and
some sensitive American neutralised triode TRF receivers were provided
with loop aerials that could be folded
away inside the cabinet when not in
use. By the use of a jack plug that disconnected the input tuning coil, use of
the loop could be optional.
111t'rT,-,
Loops in decline
The situation changed after 1930 with
the widespread use of mains power and
the modern high gain and stable super het. Often, a short piece of wire was
adequate for an aerial.
For most of the decade, loop aerials
and portables were generally neglected.
The term `portable' still referred to the
provision of carrying handles rather
than compactness and convenience, and
running costs were high.
In America, car radios, for which the
loop aerial was not satisfactory, became
popular during the 1930's, and the few
portables that were produced had wire
aerials. Here the situation was much
same. The STC 506 portable described
in EA for April 1989 was typical. Although it had a door suitable for housing a loop, a wire aerial was preferred,
and the chassis was no different from
the household model.
Revival
In 1939, the advent of the new 1.4
volt battery valves meant that portable
radios could live up to their name,
rather than just being radios with handles.
Portables suddenly became popular
here and in America, and now with
them, loop aerials. These were generally flat spirals, mounted in the lid or
back of the cabinet.
The same manufacturers `discovered'
that loop aerials were also very practical
for mains powered receivers, something
that a small number of British manufacturers had never forgotten. Terminals
were generally provided so that the user
could connect a conventional aerial if
desired.
Most of these loop -fitted receivers
were small `mantle' sets, popular for
apartments and `second sets'. But one
American manufacturer, General Electric, brought out an ambitious model
using their 'Beam -A -Scope' loop aerial.
A large console cabinet contained a
rotatable loop fitted with a Faraday
electrostatic shield. By shielding the
aerial, much local electrical interference
would either not be picked up, or could
more readily be nulled out.
Monster loop
Fig.3: This spiral loop belongs to an
FADA
American
model
480B
Neutrodyne receiver built in 1927,
and can be folded away in the top of
the receiver when not in use. Only a
few large US receivers from this
period were supplied with loops. The
480B used four tuned RF and three
audio stages.
What must be one of the biggest
loops ever, was built around 1940 by
the New Zealand Post Office for receiving long -wave transmissions direct from
Rugby in England. As I recall, it was
about 10 metres square, constructed between two large telegraph poles. Each
pole was fitted with four standard 8 -insulator cross arms, supporting 16 turns
ELECTRONICS Australia. August 1990
153
VINTAGE RADIO
layers. Total length of wire
would have been something like 600
metres!
By the early 1950's radio coverage
had improved considerably and extreme
sensitivity was no longer necessary.
Loop -equipped receivers became increasingly popular, due in part to the
absence of dangling leads and random
bits of wire.
Around this time, the 'DX' (long distance reception) fraternity started taking
loops very seriously. In reception of the'
now -crowded broadcast band, the combination of the directional properties of
large tuned loop and a sensitive receiver
worked wonders in digging out elusive
in two
j
Iron cored loops
Fig.4: By 1947, portable receivers were reasonably small and were able to
produce acceptable results from small built-in loop aerials. This one is
mounted on the back panel of the case.
Also, during the mid 1950's one of
the most significant developments in domestic loop aerials appeared, in the
form of the familiar ferrite rod aerial.
This is, in reality, a small diameter loop
with a powdered -iron core to intensify
the electromagnetic field. Performance
is roughly equivalent to that of a loop
with a diameter equal to the rod's
length, and its small size restricts unwanted electrostatic pickup as well as
making it physically convenient.
It was fortunate that the ferrite aerial
turned out to be ideal for coupling to
bipolar transistors. Had the ferrite loop
not been available, it is unlikely that the
small transistor AM radio as we know it
signals.
National
would have evolved, and today's domestic radio situation would be very different.
Now, a century after the Hertz experiments, there are millions of ferrite
loops in use, and there is no immediate
threat to their continuing and justified
popularity.
T Series Relays
Tiny relays for telecomms,
telemetry and tight spaces.
TQ
TF
The pioneer in its class and now
the industry standard.
2 and 4 c/o latching options
TTL and CMOS compatible,
a mere 80mW operating power
Same pinout as the TQ,
48VDC coil and SMD options
,
r
+ j^..
hit
TN
M
TF
TQ2
Slimline. TQ features In a
space saving package.
Australian Distributors
(occupies only 5.6x14mm)
T -Series feature 30Watt gold -clad
7
TQ4
1
TN
Ad._
contacts,
2msec. operate time, low thermal EMF and
excellent RF characteristics up to 900MHz
R
RVB PRODUCTS PTY. LTD.
23 Dehavilland Rd, Braeside. Vic 3195.
Tel. (03) 580 0688 Fax. (03) 587 3532
6/220 Pacific Highway, Crows Nest 2065.
Tel. (02) 957 6385 Fax (02) 929 5334
i
154
ELECTRONICS Australia. August 1990
READER INFO NO. 40
AMATEUR RADIO
Amateur
Radio
Hobbyists communicating world
wide using state-of-the-art
electronics.
News-
Aust. & world records
- continued
Are you into computers?
Like to access BBS around
the world by radio?
Interested in different forms
of digital communication
Current World Records
Here's the second part of the listing
of current Australian records for VHF,
UHF and SHF contacts, kindly sent in
by John Martin VK3ZJC, Acting Chairman of the WIA's Federal Technical
Advisory Committee (FTAC). As
promised this part lists the records for
EME, ATV, mobile and digital modes,
as they stood in April this year. As before the 'N' code shows a national
record.
Also shown are the current world
records, for both terrestrial and EME
contacts. Where a band is not listed,
there is no current record claimed.
Australian Records
Band
50MHz
70MHz
144MHz
220MHz
432MHz
576MHz
903MHz
1296MHz
Terrestrial
2300MHz
3300MHz
5650Mhz
10GHz
24GHz
47GHz
75GHz
474GHz
1885.5km
1885.5km
981 km
1660 km
331 km
87 km
0.5km
15 km
3465 km
7860 km
5906 km
4103 km
382.9km
769 km
4068 km
EME
13256km
- AMTOR - PACKET?
19455km
8139km
18783km
WHY NOT BECOME
A RADIO AMATEUR?
30km
18657km
Want to know more?
13931km
802km
279km
Join the WIA - the oldest and most
experienced radio society in the
world - always at the forefront of
radio communications for hobbyists.
Receive AMATEUR RADIO, the
monthly magazine for members of
the WIA, full of news of DX, clubs,
satellites, technical articles
and lots more.
EME Category
144MHz N
432MHz N
1296MHz N
432MHz
N
144MHz
432MHz
576MHz
1296MHz
N
50MHz
N
N
N
N
VK3ATN
VK6ZT
VK3AKC
VK7EM/T
VK3KAJ/M
VK3KAJ/M
VK3KAJ/M
VK3ZJC/M
K2MWA/2
K2UYH
W2NFA
ATV Category
to VK3ZPA/T
Mobile Category
to VK6BE
to VK6BE
to VK3ZBJ
to VK3KKW/M
to
to
to
28/11/66
29/01/83
06/10/73
16761.0km
18726.4km
16713.0km (3)
13/12/72
413.0km (4)
25/01/86
25/01/86
26 02/89
16/09/89
Other WIA services include:
A world wide QSL card service
Weekly news broadcasts
Classes for all grades of
amateur licences
Correspondence lessons
available
Meetings, contests, field days
Representation for radio
amateurs at Government level
2224.5km
2224.5km
122.5km
137.6km
Digital Modes Category
VK3ZJC
NOTES:
to
(3)
(4)
26/12/88
1906.3km
VK3AKC: R. Wilkinson (deceased)
VK3ZPA now licensed as VK3KAU
VKBZLX
Free licence examinations
An organisation called West Ham
Examinations has been set up in the
west of Sydney, to provide an independent, economical alternative for those
wishing to sit for the AOCP examinations.
Normal fees are set at the low fee of
$5 per subject. But for high school students and members of the NSW Division of the WIA, the fees are to be
Regular examinations will be held at
Birrong Boys' High School, with country candidates and clubs invited to use
WHE's exam papers under local supervision. Exams are scheduled for August
12, October 14 and December 9.
Further information is available from
West Ham Examinations, 13 Iris Street,
Sefton 2162 or phone (02) 644 9193.
Move for new QSL bureau
A group of Victorian amateurs is ap-
parently unhappy with the methods
used by the WIA's Victorian Division in
dealing with incoming QSL cards for
non members. The group is seeking
user and/or moral support from other
amateurs, for the idea of setting up an
alternative Victorian/Australian QSL
bureau.
Learn more about the WIA and
Amateur Radio
waived.
Forward this coupon, or write to:
WIA EXECUTIVE OFFICE
P.O. BOX 300
CAULFIELD SOUTH
VICTORIA 3162
Registered address: 3/105 Hawthorn Road
Caulfield North, 3161
Please send a WIA information package to:
NAME:
The initial intention is to set up an
`inward bureau' only, on the 'return envelope' basis.
Amateurs are invited to register their
support by writing to PO Box 432, Abbotsford 3067. If there is insufficient response, no further research will be conducted and the concept will be shelved. m
ADDRESS:
POSTCODE
E001 A,
L
READER INFO NO. 41
ELECTRONICS Australia, August 1990
155
rmation centre
Conducted by Peter
Phillips
Shedding some light on the subject
Ever wondered what a 'fiscal horse' is? Or why some fluorescent light circuits use filament
heating and others don't? Find out the answer to these questions and more, in this month's
exciting collection of reader letters.
Now that the magazine ETI has been
merged with EA, letters concerning ETI
projects are making their way to my
desk. No problem
1
spent several
.years with ETI before joining EA, and
have a working familiarity with at least
some of ETI's projects. Unfortunately,
my filing system such as it is does not
include all past issues of ETI, and references to a particular project usually require me to access the circuit.
In the interests of being able to offer
assistance on these projects, I have a
small request. If you want some help
-
with projects from ETI, please send a
photocopy of at least the 'How it
Works' section and the circuit diagram.
This doesn't guarantee an accurate response, or even a response that is useful, but it will help me considerably in
answering your questions.
We also occasionally get letters about
projects from other electronics magazines, both local and imported. Usually
we cannot help with these, unless the
answer is of a very general nature and
of interest to all readers. Again a copy
of the circuit will help, but don't be too
upset if we fail to respond on these
types of requests.
We'll start with two letters that fall
into the category of those I've just mentioned, followed by a most varied range
of topics.
I have recently constructed a mixer circuit from the Fagazine Hohhv Electronics, (HE 112), and found it worked very
well. I now wish to add a VU meter to
the output to monitor the level of the
audio output signal. To this end, I have
scrounged a VU meter from an old tape
recorder, and have tried connecting it in
series with a I0k pot and a diode to the
output of the mixer.
However, die needle only stays at the
setting determined by the pot, and doesn't fluctuate with the audio level. Can
you assist me with this, as I wish to use
the meter to indicate the relative outputs
of a camera, a microphone and some
music for recording onto a VCR. (D.S.,
Frankston Vic).
The circuit of the mixer was supplied
by D.S., and consists of an LM30I op
amp connected as a two input summer.
The gain of one channel is set to a maximum of 10 (mic input), and the other
to a maximum gain of one. The output,
which is biased to 4.5V DC as the op
amp is supplied by a single 9V battery,
connects to a socket via a IOuF capaci-
tor.
A VU meter circuit that works (I
tested it, by the way) is shown in Fig.',
which seems to be similar to that de c1
o
156
10}iF
RV1
5k
VU meter
The following letter asks our advice
about a mixer circuit from the magazine
Hobby Electronics. Because the question is not really about the circuit we
don't mind helping out with this one.
Normally we'd sac nasty things like ask
them , hut the question is not specific to
the project and our answer is probably
of general interest.
Fig.1
+a
C2
1yF
D1
1N914
Vu METER
150NA FSDI
scribed by D.S., although he did not
mention using a capacitor across the
meter as shown in my circuit (C2). The
only effect this capacitor will have is to
increase the deflection, so its exclusion
ELECTRONICS Australia, August 1990
for the circuit to indicate
steady value rather than the audio
level.
It seems clear that there is a DC component affecting your meter, D.S., either caused by a faulty coupling capaciis not a reason
a
tor or a wrong connection. The meter
must have a capacitor in series with it
(C1), and if this is an electrolytic type,
it needs to be correctly polarised.
Chopper effects unit
The next letter asks about an ETI
project. The correspondent didn't send
a circuit but as it turns out,
can help
anyway.
1
Looking back through past issues of
ETI, 1 encountered a circuit of a Chopper Echo -Effects Unit on page 106 of the
January 1984 issue. The only worry with
this circuit is the VN67AF FET, which
no one seems to have heard of. Please
help, either with the name of a supplier
or a substitute for this elusive device.
(G. K., Dunkeld Vic).
Whenever I can't find a component, I
reach for a Farnell Electronic Components catalog. And yes, they have the
VN67AF FET listed, at a price of
$2.75. Their address is 72 Ferndell
Street, Chester Hill, NSW, 2162, and
the phone number is (02) 645 8888.
According to the Farnell catalog, the
VN67AF has the following characteristics: N -channel power MOSFET, VDS
of 60V, drain current of I.6A, TO -220
package with the connections shown in
Fig.2. Note that the drain tab connects
-d
sqd
Fig.2
to the lead on the right. not the usual
centre lead.
Feel no pain
Occasionally I like to print items of a
humorous nature, and the next letter is
certainly that. The original letter was
too long to print in its entirety, so I've
taken the liberty of condensing it.
On the day in question, my wife
joined me after work so we could walk
home together. As we passed the local,
we decided to share a drink or two with
some friends, to wash away the cares of
the day. I have to admit that I had somewhat more than two, and as my wife had
long since departed for home, alone and
most unimpressed, I eventually decided
to follow suit.
On the way I came across a man attempting to start his car. He couldn't
refuse my effusive 'Wanna hand' and
when the engine came into focus I reasoned 'it's either no spark or no petrol.'
I decided to test for spark and holding
onto the car chassis with one hand and a
spark plug lead with the other, I invited
him to crank the engine. 'Dead as a dormouse' I informed him after several seconds of testing.
He didn't believe me, so I suggested
we change places, to which he timidly
agreed. The next thing I recall is seeing
this poor man launch vertically as I
switched on the ignition and started
cranking the engine. As I helped him out
of
a hedge some three metres from the
car, he shook his head and after making
oblique references to the Lord, took off.
The next day on my way to work,
there he was again, still trying to start the
car. As I approached, a look of absolute
fear crossed his face, so taking the hint,
i kept going. I still wonder how it all
happened, but honestly, I never felt a
thing! (D.L., Tumblong NSW).
Portable fluoro
I have received three letters that in
some way refer to the Portable Fluorescent Light project published in March
and April. The first is from a reader
who relies on battery power...
Further to the battery powered fluorescent light project, / have a 12V battery
light that has two 8W tubes
not work-
-
ing, of course.
Be it Norm Bush's unit, your modified
unit or whatever, is the design suitable
for 8W tubes? Would I have to use one
kit for each tube, or could it be modified
suitably to be used to run both tubes?
Hope I'm not being a pain. Keep up
the good work.
(R.H., Glenreagh
NSW).
Of course you aren't 'being a pain',
R.H., thanks for taking the trouble to
write to us. As the circuit stands, it
should be able to operate an 8W tube
quite successfully. However, it would
not be able to operate two 8W tubes
without severe overload and probable
damage to the transistor.
Norm Bush has since informed me
that he is working on a unit that will
operate higher wattage tubes, intended
to be run from a car battery rather than
being portable. In the meantime, a
12/240V inverter circuit for an 18W
fluorescent tube was described in the
Circuit and Design Ideas (CDI) section
of the January 1990 edition, which may
be suitable for driving two parallel
tubes. It will need some adaptation
however, and the simplest way is to
purchase an 18W tube rather than try
adapting two 8W tubes.
The next letter asks a question that I
really cannot answer!
I have come across some difficulty
with the low-cost fluoro lamp project
that appeared in EA March/April, 1990.
I have two transformers exactly like the
one shown in the photo on the bottom of
page 71 of the March issue. My problem
is that I don't know which wire on the
transformer corresponds to the ones
shown on the circuit diagram above the
photo. Can you tell me which wire goes
where; they are all different colours on
the transformer? (G. S., Loftus NSW).
In a word, G.S., No! Even though
the transformer may look the same, the
windings inside are most unlikely to
have the same number of turns as those
specified in the project. I suggest you
dismantle the transformer, unwind each
of its windings and then rewind it as described in the article. You may even be
able to use the original wire, providing
it is not damaged and is around the size
specified. This way, you can use the
core and maybe the wire, but don't try
as it stands.
The layout diagram has numbers next
to each wire, which correspond with
similar numbers on the circuit diagram.
The numbers on the layout are a bit
hard to see, and are simply numbered 1
to 6 from top to bottom. The winding
details are shown clearly in Fig.2 on
page 72.
The final letter asks why are the heaters sometimes used in a portable fluorescent light circuit.
The articles in the March and April
issues on battery fluorescent lamps make
no reference to use of the tube filaments
as preheaters.
They are most commonly used without
pre -heating, but I have noted one combination torch fluoro and a caravan ceiling
light where one filament is preheated, as
indicated by two connections to one end.
Selectronics in Victoria make inverters
that preheat both filaments. This raises
interesting questions as to the effects of
this feature on circuit complexity, performance and cost. (M. C., Busselton
WA).
To the best of my knowledge, the
reason tubes are sometimes pre -heated
is because the initial firing voltage from
the inverter is too low to ionise the gas.
By heating the gas, even at one end,
ionisation can occur more easily and
subsequently at a lower voltage. The
CDI circuit referred to above heats one
filament and also has an earth plane to
get the tube going.
An inverter that gives a very high output under no load is probably not regarded as a good design, due to its inherent poor regulation. However, a
'well designed' inverter is not able to
fire a fluorescent tube, so filament heating is required. Obviously an inverter
with good regulation is likely to be complex, and filament pre -heating is required as well if it is driving a fluorescent lamp. Which all adds up to overall
complexity, making the simpler circuit
designed by Norm Bush look rather
good.
An article on fluorescent lamps was
published in the January 1990 issue of
EA, which may throw some more light
(pardon!) on the topic.
Patents & French horses
Two letters have arrived that make
reference to the May 1990 article I
wrote about an old book on dynamos.
The first draws attention to that fascinating place called the Patent Office.
1 wonder, following your article about
the remarkable old book on dynamos,
whether you might write a similar article
about the Sydney Patent Office. This office is located in Kent Street near the
Harbour Bridge, and is virtually a library, containing some incredible literature.
Time spent in this office may well give
readers insight into how to make items
that could be most useful to them. I have
enclosed an example of the sort of literature that the office allows to be photo-
(G.L., Waratah NSW).
The article supplied by G.L. was indeed most interesting, being a patent
specification for an 'improved hand sawing apparatus' designed by one Ernest
Zimmerman, and lodged in March 1944.
i must admit to not being familiar with
copied.
ELECTRONICS Australia. August 1990
157
might stretch to 746W given good hay).
An interesting sidelight is that the
French term 'cheval de vapeur' (steam
horse) serves to avoid confusion with another beast `le cheval fiscaux' (fiscal
horse). The symbol for this rather quaint
unit is CV, as in the recently deceased
2CV Citroen. A fiscal horse is actually a
unit of volume, about one sixth of a litre
according to Robert, and is used to
determine the registration fee for cars
and motorcycles ín France.
Thus, the 2CV originally had an engine displacement of around a third of a
litre. However the name persisted as an
historic feature only, ás recent 2CV's actually displace 4CV and may be driven
up hills without manual assistance. Not
quickly, mind you!
Le Robert is the French equivalent of
the Oxford English Dictionary, and has
a very large entry on horses. (G. B.,
Parkside SA).
I enjoy letters like that from G.B., as
INFORMATION CENTRE
the workings of the Patent Office, or
even of its location, so I am most grateful to you G.L., for sending me this in-
formation.
If time permits, and the resulting
story is sufficiently `electronic in nature', I will indeed take up your suggestion. In fact, the general topic of patents is likely to be of interest to many
readers, and is one well worth pursuing.
The next letter throws some light on
the `cheval de vapeur' referred to in the
article about the old book.
1 was intrigued by the difference between French and English horses, noted
in your article on 19th century dynamos.
The Petit Robert provided the answer:
`un cheval de vapeur (ch)' is 75kg.ms'r,
or 735 watts. English horses know nothing of this metric nonsense however, so
they will lift 550 foot pounds per second,
which equates to around 743W (which
432MHZ CONVERTER (June 1990): In the overlay diagram
on page 120, there should be black dots on the pads of L4
and VC4 that are not connected to tracks on the underside
indicating a connection to the top ground
of the board
plane copper. The 90cs5t copper pattern reproduced on page
121 is also in error, showing copper relieved around the
leads of C14, C17, C4 and C7 which should connect to the
ground plane. The copper is also incorrectly relieved around
the emitter leads of Ql and 02, whereas it should be shown
relieved around the collector leads of both transistors. A re -
-
FROM VCO
50-54MHz
O
000
O
O
o
o
O
O
0
000
0
0
0
o
8
00
O
oo
O
O'
o
90csS
o
O
420-450MHz IN
158
Here's a very simple question that
often elicits the wrong answer. A 10uA
meter movement is connected in series
with a resistor so it can read voltages up
to 100V. If the meter is connected to a
circuit and indicates 27.9V, determine
the equivalent resistance the voltmeter
represents at this voltage.
ELECTRONICS Australia. August 1990
6M NBFM RECEIVER (January/March 1990): In the PCB
overlay on page 85 of the March article, the lower end of capacitor
marked
ground
coil L3
resistor
and the upper end (-) of C19 should both be
a black dot to indicate a connection to the
plane copper. Also the component directly between
and 1C3 should be marked C3, not R3, while the
between C14 and C17 should be marked R16, not
Cl
with
R22.
The PCB pattern also has a small error. The ground plane
copper should be relieved around the anode end of diode
D4, which connects to R10, C23 and pin 13 of IC3. A small
drill (approximately 3mm) should be used to remove a small
area of copper from the ground plane copper before mounting D4, to prevent accidental grounding. Neither end of D4
connects to the ground plane.
144MHZ CONVERTER (May 1990): On the top (groundplane) copper layer of the PCB, the track coming from pin
the copper
20 of IC11 should connect to pin 5 of IC7
should not be relieved around this pin.
In the circuit schematic, the 1.8pF coupling capacitor between Ll and L2 should be marked Cl. Also VC6 is a 40pF
trimmer.
The parts list should call for only one 330 ohm 1/4W resistor, but two 10k 1/4W resistors.
In the overlay diagram on page 88, C17 and C23 should
have polarity markings shown. The positive side of C17 connects to pin 16 of IC9, while the positive side of C23 connects to R20. Note that the black dots on the overlay diagram indicate where IC pins and component leads connect to
both top and bottom copper layers.
-
00
0 0
.O
O
o
0
O
O
O
c
00
o
0
O
00
O
O
80
O
0
What??
vised version of the 90cs5t pattern is reproduced here, and
copies have been sent to the various PCB manufacturers.
NOTES & ERRATA
OUT
I love technical trivia. I also share a
fond regard of the Citroen car, and always wondered where the term CV
came from. At the time of writing the
article I figured the difference in the
horses to be the time-honoured 735W
versus 746W conundrum, but I wasn't
sure. My French is un peu poor, so I
decided not to offer an explanation in
case I was wrong.
Many thanks G.B., both for your letter and for the humorous style you
chose. It was most enjoyable to read.
t
Fig.3: Here is the corrected ground -plane pattern for the
432MHz converter PCB, as discussed above. This should
be used to replace that published on page 120 of the
June issue.
Answer to last month's
THIS MONTH'S SPECIALS!
What??
The answer to last month's What?? is
30 ohms and 70 ohms. To solve the
problem, a quadratic equation is derived from the expressions: (a) Rl +
R2 = 100 and (b) (R1R2)/(R1+R2) =
21 ohms. From these, R2 equals 100R1, which can be substituted into (b).
This gives, after simplification and rearranging, the quadratic equation of: R12
- 100R1 + 2100 = 0. Solving for R1
gives 30, leaving 70 for R2.
BRIDGE
RECTIFIERS
[M1104
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ZERO INSERTION
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(ZIF's);.
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79I2KC t--1 ve 12v
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NOTES
&
ERRATA Continued
off
Did anyone spot my deliberate mistake on page 157 of June's Information
Centre. Seriously, just how it happened,
is a complete mystery. I plead 'temporary insanity', brought on by overwork,
and my face is a very bright shade of
red. But I'm not on my own
guess
who has to do the final check of finished copy. Below is the diagram right
way round. My apologies to all the very
confused EA readers.
(Milli - Production Ed.)
.
,
.
S1.50
..
SI.50
S1.50
PLUG PACK
CASE
FERGUSON TYPE
PLIERS
only
VIA 24"vAC 279 ohnis
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MA511
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CAPACITORS
INDUSTRIAL
SEMI CONDUCTORS ELECTRONICS
ALL ELECTRONIC
Co
t'
I
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118-122 Lonsdale Street, Melbourne, Vic. 3000
Telephone: (03) 662 3506 Fax: (03) 663 3822
WORLD
...
-
e.;.
items including.
Please add 54.50 for orders under 550 (within
A
55.00
el
REMEMBER! we also stock a large range of
ARP
"All orders over 550 despatched post free.
Australia).
Apologies:
.
.
.
BARGAIN
12VDC RELAY
COMPUTER
NEWS & PRODUCTS
(June 1990): The Labcard PCL-718 described on page 54 is not available from
Control Dynamics, but from Priority
Electronics of Suite 7, 23-25 Melrose
Street, Sandringham 3191 or phone (03)
521 0266.
$25.00
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READER INFO NO. 42
ELECTRONICS Australia. August 1990
159
50 and 25 ,ears ap o..
'Electronics Australia' is one of the longest running technical publications
in the world. We started as 'Wireless Weekly' in August 1922 and became
'Radio and Hobbies in Australia' in April 1939. The title was changed to
Radio, Television and Hobbies' in February 1955 and finally, to 'Electronics
Australia' in April 1965. Below we feature some items from past issues.
August 1940
Panoramic Reception:
`Panoramic reception' is a name given
to a newly devised method of receiving
many stations simultaneously, by its inventor, Dr Marcel Wallace, of New
York. The system is so simple that most
engineers who have seen it demonstrated wonder why it has not been put
into practice long before this.
The first announcement published in
Electronics was printed in July 1938,
page 36. Since that time more complete
apparatus has been built and a demonstration of the system has been made to
officials of the Civil Aeronautics Authority at the Indianapolis Airport, to
show its effectiveness as a radio range
beacon for aircraft.
Essentially, panoramic reception is accomplished by observing radio signals
on the screen of a cathode-ray oscilloscope. The receiver is a conventional
superheterodyne in every respect except
that the circuits of the oscillator and antenna are tuned continuously from one
end of the band to the other at a rate of
about 60 times per second.
The receiver thus sweeps past the signals present on the band and registers
an audio output voltage as each signal is
'encountered. The output is applied to
the vertical deflection plates of an oscilloscope. The horizontal sweep frequency of the oscilloscope is controlled
so that it is synchronous with the 60 per
second tuning cycle. Hence each station
on the band registers as a stationary
vertical deflection of inverted -V shape.
EA CROSSWORD
9. Those who copy tapes. (7)
10. Again bring to a focal point.
(7)
11. Stuff your memory! (4)
Across
1. Secondary power source.
(4-2, 7)
2
1
-4
3
6
5
13
12
11
26
22
21
a
29
23
25
a
28
30
32
33
-
160
I
ELECTRONICS Australia, August 1990
JULY SOLUTION
to readings. (7)
Part of the electromagnetic
spectrum. (1,1,1)
Resists. (7)
Site of stored LP data. (6)
Filter type: ---- pass. (4)
Full of bright energy. (5)
Make a zone secure. (4)
Mention details required. (7)
What 5 down can do for you.
(7)
Device used as a voltage
controller. (13)
2. Components of radio
systems. (7)
3. Sets for EA projects. (4)
4. Unit of pressure. (6)
5. Acronym for tertiary
14.
15.
17.
18.
19.
21.
institution. (4)
Respond to radio signals. (7) 23.
24.
Quality of matter that
prevents electromagnetic
25.
wave propagation. (7)
8. Determine mineral content.
29.
(5)
30.
10. 3D effect, as seen with
6.
7.
31
LDX is a system for high-speed transmission of line copy that electronically
sends a document across a corridor, or
across a continent. In seconds, a scanner is able to send to a printer, anything
written, typed, sketched or printed. The
link between these two components is a
broadband transmission line (microwave
channel, coaxial cable or special telephone lines).
The original document remains with
the sender while the device converts an
image of the document into electrical
impulses and transmits them thousands
of miles away or across town to a receiver.
The system is a combination of optics,
electronics and electrostatics. A cathode-ray tube in the scanning unit
sweeps across the original document. A
photo -multiplier converts the light from
the scanned page into electrical signals
that are then sent via the broadband
link to the printer unit which can be
thousands of miles away. The received
signals are fed to another cathode-ray
tube which `redraws' the image on a sem
lenium coated drum.
Down
19
18
24
20.
22.
26.
27.
33.
17
16
20
18.
15
14
Long-distance instant copy:
12. Carrier of signals. (5)
13. Insulating mineral. (4)
16. One who checks. (6)
17. Device giving more accuracy
28.
31.
32.
10
August 1965
scanning electron microscope. (6)
Message system. (5)
Property of neon. (5)
Type of video. (1,1,1)
Confirm. (6)
Sent a return message. (7)
Device that induces a high
voltage. (7)
Function. (7)
Form of domestic supply,
three ----. (5)
Instrument that indicates
pace (abbrev.). (6)
Trigonometrical function. (7)
Adjust frequency. (4)
EA
with ETI marketplace
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TOSHIBA T3100: co -processor kit. This
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types avaialble, solder in and plug in.
Solder ver. $190 plug ver. $335
IMPORT TECHNOLOGIES 07-3725138
CB RADIOS: $59 to $199, business,
amateur, marine, outback, world wide
radios, scanners, power supplies, aerials, walkie talkies, amplifiers, test gear,
microphones, HF, VHF, UHF, different
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repair. Enquire about hobby radio and
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Sam Voron, VK2BVS 24 hour, 7 day
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- - - -
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82-1166.
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Improve diagrams, reports and presentations.
Phone: (02) 606-6752
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For all transmitter and receiver applications. Send DL size SASE for data/price
to: RJ & US Imports, PO Box 157, Mort dale, NSW 2223. Agencies at: Geoff
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ACT; Truscott's Electronics, Melbourne; S. Willis, Perth; Assoc TV Service.
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You can now purchase any of these specially selected books from the easy to order
Electronics Australia Bookshop.
Titles cover a wide range of electronic, scientific, and technical books and will be
updated regularly to keep you abreast of the latest trends.
Simple Tropical and MW Band Aerials
Test Equipment Construction
An Introduction to Satellite Television
Computer Music Projects
How to Get Your Computer Programs Running
The Simple Electronic Circuit & Components (Elements of Electronics
BP -145
BP -248
BP -195
BP-173
-
BP -169
Book 1)
BP -062
Chart of Radio, Electronics, Semiconductor and Logic Symbols
Electronic Music Projects
How to Design Electronics Projects
25 Simple Amateur Band Aerials
25 Simple SW Broadcast Aerials
An Introduction to Z80 Machine Code
Radio & Electronic Colour Codes Data Chart
BP -027
50 Projects Using Relays, SCRs and TRIACs
50 Simple LED Circuits
BP-037
Popular Electronics Projects
Practical Electronics Calculations and Formulae
Your Electronic Calculator & Your Money
Electronics Security Devices
Choosing and Using Your Hi -Fi
Transistor Radio Fault -Finding Chart
Power Supply Projects
How to Use Op -amps
Communications (Elements of Electronics
Book 5)
Audio Projects
Model Railway Projects
IC Projects for Beginners
Mini -Matrix Board Projects
Aerial Projects
30 Solderless Breadboard Projects
Book 1
Audio Enthusiasts Handbook
Build Your Own Solid State Hi -Fi and Audio Accessories
Beginners Guide To Building Electronic Projects
BP -049
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The Art of Programming the 1K ZX81
How to Get Your Electronic Projects Working
BP -109
Remote Control Handbook
BP -240
A Z-80 Workshop Manual
30 Solderless Breadboard Projects
The Pre -Computer Book
--
-
BP-110
BP -112
Book 2
BP -113
BP -115
Practical Elec. Building Blocks
Book 1
Practical Elec. Building Blocks
Book 2
Audio Amplifier Fault-Finding Chart
How to Design and Make Your Own PCB's
Audio Amplifier Construction
25 Simple Indoor and Window Aerials
BP -117
An Introduction to Programming the BBC Model B Micro
Digital IC Equivalents & Pin Connections
BP -139
Linear IC Equivalents & Pin Connections
Further Practical Electronics Calculations and Formulae
The Pre -BASIC Book
An Introduction to 6502 Machine Code
An Introduction to Computer Peripherals
More Advanced Electronic Music Projects
An Introduction to Computer Communications
Electronics Circuits for the Computer Control of Robots
Electronic Circuits for the Computer Control of Model Railways
MIDI Projects
Electronic Synthesiser Construction
Using Your Amstrad CPC Disc Drives
LOGO for Beginners
Electronic Hobbyist Handbook
Getting the Most from Your Multimeter
International Radio Station Guide
Digital Audio Projects
More Advanced Test Equipment Construction
From Atoms To Amperes
How To Use Oscilloscopes and Other Test Equipment
An Introduction To Loudspeaker and Enclosure Design
BP -141
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handling. If the coupon is missing, write down the names, code numbers and prices of the books you
require. Include your name, address, telephone number, plus cheque, money order or credit card
details (card type, card number, expiry date and signature) and send it all to: Federal Publishing,
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To order, simply
Silicon Valley
plp
r
,L"'`".s© ,aLI.1,11151M°
3
Motorola, IBM launch
radio data network
In a joint announcement, Motorola
and IBM have built a huge radio -based
network that will allow users of portable, laptop and hand-held computers
to tap into their office systems from
nearly anywhere in the United States.
Using the service, a field service repairman can record data about a particular job into the company's central
computer, and check the availability of
certain parts in the company's inventory. In return, the office can send the
serviceman information on his next call.
Besides enhancing communications
between computers used by workers in
the field or on trips, the network could
mean a huge boost to the field of tele commuting and allow vastly more workers to work at home at least some of
the time.
"We are going to enable workers access to data they have nevery had before," said IBM's Jack Blumenstein,
who was named president of the joint
venture which is called 'Ardis.'
The service began operation in April
and competes directly with cellular telephone services which enable computer
users on the road to communicate with
their office by hooking a modem or fax
to their cellular phone. IBM and Motorola believe their system is better suited
for computer users because the computer remains on-line with the central
system at all times.
While exact prices still remain to be
set, the service is expected to cost between $100 and $150 per month per terminal. Motorola already sells terminals
for its cellular phones that can also be
used for the Ardis system. IBM has developed a terminal of its own but would
not say when, or if it will bring the
product to market.
National sues
Schlurnberger
over Fairchild sale
Much of National Semiconductor's
financial problems of the past two years
have been blamed on the Fairchild
164
r
'y
-
`' !
operations it acquired from Schlumberg
in 1987 for US$125 million. Now National claims that price was too high,
and has filed a $20 million lawsuit
against Schlumberger.
In the suit, National accuses Schlumberger of misleading it about the value
of Fairchild's assets. At the beginning of
the negotiations, Schlumberger, according to National, deliberately undervalued Fairchild's net worth. Towards the
completion of the acquisition talks,
Schlumberger showed that Fairchild's
value had increased substantially and
National found itself paying US$14 million more than it originally had agreed
tion Carla Hills said Japan would not be
placed on this year's `Super 301' list of
countries engaged in unfair trading
on.
Now National wants its money back,
plus damages and legal fees.
in the past year."
Siliconix talks
about settlement
Siliconix, the Santa Clara -based
power semiconductor maker which filed
for bankruptcy recently, has entered
into direct negotiations with International Rectifier.
Siliconix filed for Chapter 11 immediately after it lost a key patent infringement lawsuit and was ordered to pay IR
US$4 million in past royalties.
Reportedly, Siliconix will try to negotiate the terms of payments to IR as
well as a licence agreement that would
enable the company to continue to
make and sell products that incorporate
the IR patents.
The unfavourable judgement was but
the latest blow to Silíconix, which has
fallen on hard times after recording the
longest string of profitable quarters
(more than 144) in US high-tech industry history.
Japan avoids
`Super 301' list
A rush of trade agreements, coupled
with a series of recent foreign purchase
commitments by a number of highly visible Japanese conglomerates, and various government promises to change and
abolish trade barriers have paid off in a
big way for Japan. US trade representa-
ELECTRONICS Australia, August 1990
practices.
The announcement was sharply criticised by a number of high-ranking
members of Congress. Previously, the
Semiconductor Industry Association had
petitioned the Bush Administration to
place Japan on the list, for failing to
live up to the 1986 US-Japanese Semi-
conductor Trade Agreement.
Hills told the powerful Senate Finance
Committee that the Japanese have been
"moving further in lowering trade barriers to US products than other countries
Senator Lloyd Benson, chairman of
the panel, however said the failure to
name Japan as an unfair trading partner
could "poison the well for Congressional approval" of future trade agreements, including one being drafted with
the Soviet Union.
Last year, Japan was cited on the
Super 301 list for unfair trade in the
areas of telecommunications, supercomputing, satellites, and wood products.
301 citings set in motion a process by
which the offending country .has only
one year to negotiate an end to the unfair trade practice, or face automatic
sanctions.
Bush drops high
tech export barrier
In a dramatic overhaul of Cold War
East-West trade policies, the Bush administration announced it is dropping
trade bans on the sale of a broad variety of high-technology products to the
Soviet Union and other Eastern European countries.
The decision will open the door for
US computer, telecommunications and
machine tool firms to sell hundreds of
millions of dollars worth of products
into markets that were previously closed
or severely restricted.
The new policies will eliminate or
vastly reduce restrictions on more than
a third of some 120 product categories.
Restrictions on some 30 product groups
will be scrapped altogether. "The cur -
rent lists are too long, redundant, and
contain items that are not strategically
critical to US interests," said White
House spokesman Marlin Fitzwater in
announcing the Administration's decision, adding the changes would be presented to COCOM members at the
meeting in June.
Among the products that will be completely decontrolled are virtually all personal computers from companies such
as Apple, IBM, Compaq, and others.
Until now, US firms were forebidden
to sell computers capable of speeds exceeding 78 megabits per second. The
new rules upgrade that level to around
275 megabits.
as the centre of what it hopes will become a sprawling high-technology industrial area that will breed a new genera-
of Soviet -made computers and
other high-tech products.
In the first phase of the contract,
Bechtel will conduct a feasibility study.
Bechtel will look at the success and failure of other Silicon Valley clones
around the world and recommend the
first steps the Soviets should take to
make their effort successful.
tion
Maxtor buys Miniscribe
San Jose -based disk drive maker
Maxtor has become the industry's second largest player following the purchase of Miniscribe, whose assets were
auctioned off by the Bankruptcy Court.
Maxtor offered to pay US$46 million
in cash and stock for all the assets and
liabilities of Miniscribe, a leading producer of hard disk drives for personal
computers. With the Miniscribe operations, Maxtor will become a company
with sales of just under US$1 billion,
second only to Seagate Technology of
Scotts Valley. More important, the new
Maxtor will be able to offer customers a
full line of data storage products, ranging from
low -capacity entry-level
PC
drives to high -end engineering workstation storage systems.
The move will also put Maxtor in direct competition with both Seagate and
Connor Peripherals of San Jose, another leading supplier of personal computer disk drives. It also means the disk
drive business will be an almost all Silicon -Valley affair, with the five largest
vendors all located in the Valley.
Soviets to build
`Siliconvalleygrad'
The Soviet Union has always liked
mostly as a source of
Silicon Valley
much of its electronics technology.
Along the way, the Soviets also have
come to recognise the special circumstances that have allowed this area to
become such a fertile ground for hightech corporate development.
Now the USSR wants a Silicon Valley
of its own, and has hired the San Franciso-based engineering firm of Bechtel
-
to help create it.
The Soviets have designated an existing government research laboratory at
Troitsh, 20 miles south-west of Moscow,
'01k1
f
Digital Research Inc lost a 'big one'
in 1980, when IBM chose rival
Microsoft to develop the operating
system for its PC. After that its
fortunes waned, but since 1987 it has
made a strong comeback under the
guidance of CEO Dick Williams, a
former IBM veteran. Last year the
Monterey -based company made a
healthy profit on sales of US$36.5
million.
Japanese lead in
patent `top 10
Japan has been outspending US companies in research and development for
more than a decade. So it should not
have come as a big surprise when the
US Patent Office announced that more
Japanese than American firms ranked
among the 10 companies with the most
new patents, in 1989.
Five of the top 10 new patent holders
last year were Japanese, with the largest
number of patents (1053) by any firm
held by Hitachi
the fourth consecutive year Hitachi has taken the top spot.
Hitachi was followed by Toshiba with
961 patents, Canon with 949, and Fuji
photo film with 884. The highest ranking US company was General Electric.
-
GE held the top spot between 1969 and
1986 when Hitachi took over.
Others on the Patent top 10 were Mitsubishi in 6th place with 767 patents,
US Philips in 8th with 745, IBM 9th
with 623 and Kodak 10th with 589.
Sony making TV
tubes in Pittsburgh
In a move that could ultimately lead
to the production of HDTV sets in the
United States, Sony has announced
plans to remodel a vacated Volkswagen
factory near Pittsburgh, to produce
state-of-the-art television tubes.
The plant, where Volkswagen produced its Rabbit model for the American market, was closed in 1988 after
sales of the car had fallen off sharply.
Sony will employ some 1000 people at
the facility which is located in New San ton, 20 miles southeast of Pittsburgh.
Reportedly, Pennsylvania has offered
Sony as much as $28 million in loans
and other incentives.
The New Santon facility will be
Sony's third US television facility. It already operates a tube manufacturing
and television assembly facility in San
Diego. The company also maintains a
research operation in San Jose, where it
is in the process of developing HDTV related technologies.
Apple's 'leak stopper'
being tailed
In the latest sage of Apple's efforts to
catch employees who routinely leak
product information and other secrets to
the outside world, the executive in
charge of the spy eradication program is
himself being investigated. And he
doesn't like it at all!
Edward Stead, Apple's vice president
of law and general counsel, said he has
filed a lawsuit against a Silicon Valley
private detective agency seeking a restriction order that would keep the
firm's agents literally off his back. On
several occasions, Stead said his car had
been followed by agents of the detective
bureau as he left work at Apple.
Stead said he has no idea who hired
the detective agency of Joseph Melodia,
or why. To date, Melodia has refused to
identify who hired his company to investigate Stead.
One thing appears certain: Stead is
not being investigated by Apple, which
has denied having anything to do with
the investigation of Stead. A letter of
denial from Apple president John Scully
was included in Stead's court documents.
ELECTRONICS Australia, August 1990
165
n
Solid
II.
S
wU000U0
e
KEEPING YOU INFORMED ON THE LATEST DEVELOPMENTS IN SEMICONDUCTOR TECHNOLOGY
Power hybrids
t.
I
25 S9
?.1 National
itr/ Semiconductor
Allen-Bradley has introduced a new
range of power hybrids, designed to dissipate greater than five watts per square
inch and combine one or more technologies to produce compact and efficient devices.
The circuits vary from a single high
power switch to complete three phase
drives including six switches, output
driver and rectifier bridge.
A wide range of electrical performances are available including:
24V to 2000V,
5A to 200A,
Opto isolation to 2500V, and
Operating temperatures from -25°C
to +85°C.
100kHz.
Applications include motor drives and
switching, uninterruptible power supplies, industrial process control equipment and telecommunications systems.
For further information contact
Allen-Bradley, Electronic Components
Division, 56-60 Parramatta Road, Lid combe 2141 or phone (02) 648 2652.
With added components, additional
functions can easily be added, such as
under -voltage lockout, remote shutdown
and parallel operation of more than one
16 -bit A/D converters
Switching regulators up to 3A
National
Semiconductor has
intro-
duced the LM2579, a 3 -amp switching
regulator that can step-up, step-down or
invert voltages. The device is the latest
member of the company's switching
regulator family, which includes the
LM2575 step-down switching regulator.
The LM2579 is a very flexible part,
with a comparator input stage that simplifies circuit design. The comparator
has separate pins for both the inverting
and non -inverting inputs and an internal
1.0 -volt reference connected to each
input.
A single external capacitor is
set the oscillator frequency
switching regulator, which can
broad range from less than
used to
of the
cover a
1Hz to
device.
Further information from
Semiconductor distributors.
National
Cache address
comparators
Two cache address comparator chips
(cache tags) that can help designers
streamline custom cache memories in
high-performance systems are available
now from Texas Instruments. The industry's deepest cache tags, the new
16K x 5 -bit devices are the latest in TI's
line of processor-independent cache
building blocks. Designers can use these
products to enhance the performance of
80386, 80486, 68030 and 68040 based
systems operating at or beyond 20MHz.
With the capacity to store 16,384
cache memory addresses and address -to match delays of 20 and 18 nanoseconds
respectively, the new SN74ACT2613
and SN74ACT2164 are suitable for
80486-based systems where space on the
166
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?IS4qcr
4
%p
1g3-
motherboard is already at a premium.
For further information contact your
nearest Texas Instruments office.
ELECTRONICS Australia, August 1990
The MN6290 series of low -distortion,
sampling, A/D converters offers
a combination of resolving power, conversion speed, low noise, and low harmonic distortion.
The A/D's are packaged in small, 32 pin, double -wide DIP's and have inter-,
nal track -hold (T/H) amplifiers that enable them to accurately sample and digitise 10kHz full-scale input signals at
rates up to 20kHz.
Each device is fully FFT (fast fourier
transform) tested, using contemporary
DSP technology and guarantees up to
84dB signal-to-noise rato and up to
-88dB harmonics and spurious noise.
A high -impedance (5M) input buffer
isolates the T/H from its signal source,
and the T/H's operational mode is internally controlled by the A/D's status
line. Users need only supply start -convert pulses at the desired sampling rate.
For further information contact Priority Electronics, 23-25 Melrose Street,
Sandringham 3191 or phone (03)
16 -bit,
521 0266.
Upgraded voltage
references
C-
'555
'
$g
'
Maxim has introduced the MAX674
and MAX675 voltage references
low
cost pin compatible upgrades for the
popular REF01 and REF02.
The MAX674 and MAX675 feature
enhanced
of
drift
specifications
12ppm/°C, initial accuracy of +/0.15%,
and
load
regulation
of
-
ONE
OUTPUT
750
Si582
..:
20ppm/mA.
ryaFlt,
An output adjustment trim terminal
further refines the precision, allowing
system designers to trim system errors
by setting the output to a voltage other
than +10V or +5V. The trim adjustment is a minimum of +/-300mV on the
MAX674 and +/-150mV on the
MAX675.
aNO2b14[49.
.'
191:1
CONTROL
Wideband/video multiplexer
The DG534 is the latest addition to
the Siliconix family of wideband/video
ICs. The new IC is a logic selectable
four -channel or dual two -channel multiplexer that is used to select one of four
RF or video signals to a common output.
Manufactured with the silicon -gate
D/CMOS process, the DG534's wide band DMOS switches are connected to
a 'T' configuration, and the ground pins
are adjacent to all input and output signal pins. These design features minimise
crosstalk and optimise off-isolation.
When combined with the D/CMOS
characteristics of low on -resistance and
low drain capacitance (8pF maximum),
these features contribute to the device's
vastly superior performance.
The DG534 is available in 20 -pin plastic DIPS for through -hole applications
and small 20 -pin J -leaded plastic chip
carriers (PLCC) for surface -mount assembly.
For further information contact IRH
Components, 32 Parramatta Road, Lid combe 2141 or phone (02) 748 4066.
Lower power,
easy to use ECL
iEE
r
cost PCC packaging.
(:"A)
0.00
,,>"
.._
'R
\\\\\
20.00
(
-40.00
F100324
-60.00
50% to levels previously reserved for
TTL-based designs.
g
For further information contact Veltek, 5 King Street, Rockdale 2216 or
phone (02) 5199 1900.
20.00
F100K 300 series devices help designers by simplifying the upgrade of their
existing ECL designs. Since FIOOK 300
series parts are plug-in replacements for
IOOK devices, a simple switch can reduce system power consumption by 30-
Compatible with industry -standard
100K, 10K and 10KH ECL logic families, the F100K 300 series has the same
750ps switching as its fastest counterparts, but draws only half the amount of
power. In addition, it offers the temperature compensation of 100K and the
wide supply voltage range of 10KH.
Other unique features include minimised skew and small footprint, low-
critical.
\
,
Responding to increasing demand for
ECL logic that is as easy to use as TTL
logic, National Semiconductor has introduced its FIOOK 300 series ECL logic
family.
The MAX675 has a temperature voltoutput that supplies a voltage proportional to the absolute temperature.
This feature is especially useful for designing precision temperature transducers. At 1.4mA max, the quiescent current on the MAX674 and MAX675 is
minimal, making these references ideal
for systems where power conservation is
age
(
-80.00
.100.00
F100124
-- ---
National
WA Semiconductor
¡
-7.0V
-5.7V
-4.2V
VEE (Volts)
Performance driven application such
super -minicomputers, servers, vector
processors, fibre -optic and satellite cominstrumentation,
munications,
graphics/imaging, and radar systems
as
-2.8V
need no longer suffer the noise and
bandwidth bottleneck of TTL-based designs.
For further information contact your
nearest National Semiconductor office.
ELECTRONICS Australia, August 1990
167
SOLID STATE: UPDATE
BLOCK DIAGRAM
FEATURES
DC to 100 MHz minimum operatir,7 rog;x:rcy r;rige
Var.bM cutout OO::agus tor ECL. TTL. arc CMOS
and ta! toles (ECL: ahsl
250 o$ output
?^,0 rr' ev'ct.1 rise arG i:::i nn>Es or up to 5 Vp-O
Ac,ustaGla o::sput :xlge race from :`5g,^.s to 2000 ps
?r.,grartma.tiF otttpt.' vo:tm;oe úP to 5.5 Vp-p
Over
5V to46.5V rarx
2
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.
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IF-,.1i
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7L
VITA
VOP!i
Rabio
Monolithic 800MHz
dual pin driver
3v
JUtk3
W:CB
055 v^O
'4WD
With DC to 800MHz operation and
up to 6.5V peak to peak output swing,
Gigabit's 16G061A dual high speed pin
driver is intended for high performance
test systems designed to test current and
future generations of ECL, GaAs,
CMOS and TTL integrated circuits.
ATE manufacturers need state of the
art pin drivers with extremely fast rise
and fall times, three -state output capability, and wide output -swing. The
monolithic 16G061A pin driver has all
these key features and offers two
1.5GHz frequency
Clock -timer IC
synthesiser
with static RAM
The SP8861 is a single chip bipolar
synthesiser for professional or military
use, operating at frequencies up to
1.5GHz. The device contains all the elements, apart from the loop amplifier, to
fabricate a PLL frequency synthesis
loop.
A high degree of programmability has
been built into the part as it is intended
for use in a wide range of projects from
ultra fast switching to narrow channel
spacing. For a synthesiser of this flexibility and performance, it has a very
low operating power of typically
Drawing typically just 10uA from a
2.5 to 6V supply, the compact PCF8583
CMOS clock/timer/static RAM IC
comes in an 8 -pin DIL or surface mounted package. The IC connects to
the industry -standard I C-bus, and provides a powerful array of timing functions that include a real-time clock with
alarm functions, a calendar, and a timer
or event counter.
With a resolution of 0.01s, the
PCF8583 works as a real-time 12 or 24 hour clock/calendar, keeping track of
the year (with compensation for leap
years), month, day and day of week,
hour, minute and second. As a timer,
the PCF8583 provides elapsed time information in either days (up to 100
175mW.
The device has a very high performance digital phase detector that elimi-
nates 'dead band' effects, thus enabling
synthesisers with low phase noise to be
constructed. The inclusion of a variable
gain, reversible, phase detector allows
the SP8861 to be used in complex loops
such as those involving mixing down
from microwave frequencies.
For further information contact Plessey Semiconductors, Christina Road,
Villawood 2163 or phone (02) 72 0133.
168
hours), minutes (up to 100 minutes),
seconds (up to 100s), or hundredths of a
second (up to Is).
The PCF8583 also has an on -chip 256 byte static RAM that retains data even
when the supply falls to 1V. This can
store alarm, status or time information
as well as telephone numbers, access
codes, and other application -related in-
ELECTRONICS Australia, August 1990
drivers in one package at US$76 each in
1000 unit quantities.
The 16G061A contains two electrically independent drivers with differential ECL/GaAs compatible inputs. Outputs are switched between the levels
provided on the V high (VH) and V
low (VL) inputs with a V high range of
-1.1V to 6.5V and a V low range of
-2.5V to +1.5V. Maximum output amplitude is 6.5V. Controls are provided
to force outputs into a high -impedance,
three -state condition.
The 16G061A features a continuously
variable edge rate control (ERC) to
vary the output rise and fall times. Rise
and fall times are typically 250ps for a
1V peak to peak output (GaAs/ECL)
and 300ps for a 5V peak to peak output, and can be increased up to 2ns for
a 5V peak to peak output. Propagation
delay is 700ps for fast edge rates and
1.5ns for slow edge rates signals. Output current drive capability is 100mA.
Applications include semiconductor
ATE pin electronics, differential line receiver, switch driver, CRT preamplifier,
level comparator and translator, general
purpose driver and precision pulse gen-
erator.
further information contact
For
Gigabit Logic, 1908 Oak Terrace Lane,
Newbury Park, CA 91320 or phone
(805) 499 0610.
formation.
Timing for the PCF8583 is derived
from a 32kHz crystal or externally applied 50Hz signal.
For further information contact
Waltham
11
Philips Components,
Street, Artarmon 2064 or phone (02)
439 3322.
Solid state lamps
Sharp has released two solid state
lamps, with a hood in a totally waterproof encapsulation. These combine
super -luminosity red LEDs and high luminosity yellow -green LEDs to provide three radiation colours (red, yellow -green and orange).
The LT6600 has a radiation size of
26mm and consists of five red and eight
yellow -green LEDs to provide a total
intensity of 1800mcd (red) and 1000mcd
(yellow -green).
The LT6701 has a radiation size of
52mm and consists of 20 red and 27 yellow -green LEDs to provide a total intensity of 7000mcd (red) and 4000mcd
(yellow -green).
Further details are available from
Manuco Electronics, 21 Agnes Street,
Jolimont 3002 or phone (03) 650 3977.0
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READER INFO NO. 43
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Neptune's/ largest' satellite
Triton pictured here from a
of
about
12
corhposite
individual images taken by
Voyager 2 during its flyby on
-
_
-
August '25, 1989.
Kathryn Doolan takes us on the `Grand Tour' of Voyager's amazing journey to Jupiter, Saturn,
Uranus and Neptune, planned to culminate in the spacecraft's arrival at the boundary of our
known solar system. There, it will turn to face the Sun to take a photograph of the solar system, before continuing on its unending path.
Late August 1989, saw the culmination of one of history's greatest journeys
of exploration. Defying thé odds, and
its design life of five years, the spacecraft Voyager 2, encountered the planet
Neptune at close range for the first
time. After a 12 year journey, Voyager
2 flew to within 4000 kilometres of Neptune's cloudtops, giving scientists all
over the world their first comprehensive
look at the giant gas planet.
The idea of a `Grand Tour' of the
outer planets first came up in the mid
1960's. Scientists and engineers at the
Jet Propulsion Laboratory (JPL) in Pasadena, California, had determined that
170
there would be an opportunity for the
Tour in 1977, with the alignment of the
four outer planets - Jupiter, Saturn,
Uranus and Neptune. This alignment
occurs only every 177 years. Using what
was called a `sling shot trajectory', a
spacecraft could use the gravity of one
planet to `sling shot' itself to the next,
saving on energy and time. A conventional spacecraft fuelled by normal
means would take much longer to reach
its destination.
In 1969, NASA began detailed planning for the `Tour'. The first idea was
to launch two spacecraft to visit and ob-
serve Jupiter and Saturn, and to drop
ELECTRONICS Australia, August 1990
probes down into their atmospheres
(similar to the journey of Galileo,
launched in October 1989). One of the
spacecraft would visit Jupiter, Saturn
and Pluto and the second would visit
Jupiter, Uranus and Neptune. The estimated cost was US$ 750 million
a
large sum of money to post -Apollo
NASA
so not surprisingly, this version of the `Tour' was cancelled in 1972.
NASA planners then came up with an
abbreviated schedule. Two spacecraft
would use the gravitational slingshot to
visit only Jupiter and Saturn. The revised cost was US$ 250 million, a sum
found to be acceptable, and on July
-
-
1972, the Mariner/Jupiter/Saturn program began, with a proposed launch
date of August 1977.
The spacecraft for the journey, designed by engineers at JPL, was christened Voyager in 1975. Both spacecraft
were state of the art and incorporated
many new features. Each of the two
Voyagers weigh 825kg and stand 3.7m
tall. When the spacecraft's two booms
are extended, Voyager's width is 17.2m.
It is powered by Radioisotope Thermoelectric Generators (RTGs), which
convert the heat released by the decay
of Plutonium 238 to electricity. The
minimum total power available to Voyager ranges from 423 watts at launch in
1977 to 370 watts at Neptune.
Both spacecraft have a dish antenna
3.7m in diameter, which remains continuously pointed at Earth to receive and
send back information. Two radio receivers, one main and one backup,
transmit material using 22 watts- of
power.
Each of the spacecraft carries ten
scientific instruments, including narrow
and wide angle television cameras, spectrometers, detectors, magnetometers
and radiometers, and use the radio as
an eleventh. Most of these instruments
are mounted on a 'scan platform', so
experiments can be carried out without
having to swivel the spacecraft around
continuously.
Voyager 2 was launched into space
aboard a Titan `Centaur' rocket from
the Kennedy Space Centre on August
20 1977, and immediately ran into the
first of many technical problems.
Ground controllers at JPL received a
signal from Voyager 2 that the boom
which held the scan platform had not
been fully extended. Without the boom
deploying properly, Voyager would be
unable to use instruments on the platform, jeopardising the mission's scien-
discover an active volcano system with
several volcaneos erupting at once.
Voyager 2 observed that six of those
volcanoes were still erupting, at the
same furious pace as they had been four
months earlier.
The next stop for Voyager 1 was Saturn, in November 1980. It was found
that Saturn was surrounded by thousands of rings, comprising mainly rock
and ice. Other highlights of the stop included observation of the moon Titan,
the only moon in the solar system to
have an atmosphere comprising nitrogen
and hydrocarbons
essential to life.
After this encounter, Voyager 1 started
on its journey to the edge of the Solar
System, and is expected to reach there
early next century.
Voyager 2 encountered Saturn in
August 1981
almost its final stop, as
it turned out. After making its closest
approach to Saturn and travelling behind the .planet, Voyager's scan platform froze, limiting its movement and
making it impossible for scientists to
point the instrument at the planet.
Eventually, however, engineers at JPL
were able to start the platform again
at a lower speed, but enabling observa-
-
-
-
tions at Uranus to take place when
Voyager 2 arrived there in January
1986.
Uranus was a disappointment to the
scientists as it was bland, with no interesting surface features. The focal point
of Voyager's Uranus flyby was the
moon Miranda, described as 'the main
bizarre object in the solar system' because of its incredible mishmash of geological activity and contradictions.
Even as the Uranus encounter was
taking place, extensive plans were being
made for the Neptune encounter in
August 1989. Approval and extra
money for the flyby were granted and
JPL scientists started to wrestle with
some unique problems, not least an improved communications system.
For all its planetary missions, JPL
uses the 'deep space network', a series
of radio telescopes deployed at strategic
locations around the world, to send and
receive information from spacecraft.
The three DSN stations are located near
Madrid, Spain; Goldstone, California;
and Tidbinbilla in the ACT (which was
going to play an essential role in the
Neptune flyby).
The three main antennae at the DSN
tific purposes.
Luckily, however, scientists and engineers at JPL found that the spacecraft
sensors were incorrect and the boom
had in fact deployed. On September 5
1977, Voyager l was launched though it
almost did not leave Earth's orbit due
to a malfunctioning rocket. The problem was solved, and it eventually arrived at Jupiter in early March 1979, before Voyager 2.
Among the discoveries made were a
ring system around the planet and new
data about its moons and atmospheric
formations. Voyager 2 arrived four
months later and was witness to an incredible discovery concerning the moon
lo. When Voyager 1 had observed the
planet, scientists had been astounded to
Neptune itself, in a false colour image processed from the UV, violet and
green filtered images. This differentiates the clouds at different altitudes, by
showing them in different colours.
ELECTRONICS Australia, August 1990
171
Fareforward Voyager
The planet Neptune was first observed in 1848. It was the first planet
stations each had a diameter of 64 discovered by mathematical calculation,
metres, sufficient for communication and not through systematic observations
with Voyager until after the Uranus en- of the night sky. Two young mathematicounter in 1986. In late 1986, construc- cians, working separately and unknown
John Couch Adams, in
tion began at Madrid and Tidbinbilla to to each other
and
Urbain
Jean Joseph Le
England
70
main
antennae
from
64
to
extend the
made very similar
metres for the Neptune encounter, and Verner, in France
in mid -1988 similar construction started calculations and are both credited with
the planet's discovery. Following the
at Goldstone.
Arrangements were also made with tradition of naming planets after Greek
the Australian Government to use the or Roman gods, it was christened NepCSIRO radio antenna facility at Parkes tune, after the Roman god of the sea.
Neptune, until Voyager's recent obin NSW, as a backup for the Tidbinbilla
facility in case of technical problems or servations, was always thought to be the
bad weather. Similar arrangements were twin of Uranus, because of their similar
made to use the 'very large array' size, colour and distance from the Sun.
(VLA) in New Mexico, a series of 27 This has proved to be untrue and in
radio telescopes normally used for radio fact, the two planets share few similariastronomy. The Japanese Government ties.
Neptune is currently the furthest
also approved the use of its radio telescope, located not far from Tokyo. This planet from the Sun (four and a half bilsetup proved to be a great success and lion kilometres) and will remain so until
enabled first class data to be returned to 1999. It receives 1000 times less sunlight
than Earth does, and approximately two
Earth.
Because of Neptune's great distance and a quarter times less than Uranus.
from Earth, it would take signals from The two planets have a similar overall
the spacecraft four hours and six temperature, however, so it seems that
minutes to arrive here, so if something Neptune must have an internal heat
went wrong with Voyager 2, nothing source.
A day on Neptune is approximately
would be able to be done. Engineers
consequently programmed the space- 18 hours long and it takes the planet apcraft to keep on broadcasting if com- proximately 165 years to make one orbit
of the Sun. Before the Voyager 2 en munication with Earth was lost.
-
-
counter, it was unclear whether Neptune had a ring system; the general consensus was that the planet was surrounded by an incomplete system of
rings known as 'ring arcs.'
Neptune, before Voyager, had two
known moons - Triton, discovered in
1849, and Nereid, discovered in 1948 by
astronomer Gerard Kuiper. It was
hoped that Voyager 2 would shed new
light on the moons and discover more.
The Neptune encounter period officially began on June 5 1989, 62 days before the closest approach. During those
62 days, known as the observatory period, the spacecraft made continuous observations of the Neptunian system, its
imaging cameras monitoring atmospheric motion on the planet and looking
for ring arcs and satellites.
Eighteen days before the closest approach, the far encounter phase began
with two narrow angle cameras trying to
capture the whole planet.
The most important observations of
Neptune took place in the five day near
encounter phase. During that five days
Voyager encountered Neptune from a
distance of approximately 4850 kilometres.
With the near encounter completed,
the post encounter phase took place,
with Voyager continuing to observe
Neptune (especially the dark side of the
planet) and starting to send stored data
back to Earth.
Early in January 1989, when Voyager's images of Neptune were becoming
a little clearer to the JPL team, a dark
spot was observed, very similar to Jupiter's famed Red Spot. Other early discoveries included confirmation of a ring
arc system and dynamic activity in the
Neptunian atmosphere.
As Voyager closed in on Neptune in
mid June, the first of Neptune's new
moons was discovered. Christened
1989N, the moon ranges in size from
200 to 600 kilometres in diameter and is
orbiting the planet at an approximate
distance of 92,700 kilometres from Neptune's cloud tops. Because of N1's relative closeness to Neptune, it cannot be
seen from Earth, as the planet's brightness blocks it out.
More moons were discovered in July,
as Voyager closed in on Neptune at a
speed of 1.7 million kilometres per day.
The new moons
1989N2, 1989N3 and
1989N4
are thought to orbit in the region of the ring arcs. All the new
moons are thought to be smaller than
N1 and occupy nearly circular and equatorial orbits around Neptune. Scientists
are puzzling why all these moons orbit
Neptune in one direction, while Triton
-
A closer view of Neptune, taken using Voyager 2's wide-angle camera when
the spacecraft was 590,000km from the surface. This is an image with the
correct colour balance.
172
ELECTRONICS Australia, August 1990
-
orbits the other way.
Twelve years almost to the day, Voyager arrived at Neptune a mere 20 miles
off course after a journey of two billion
kilometres. Scientists were stunned by
Neptune's magnificent atmospheric ac-
tivity.
The main feature, nicknamed the
`Great Dark Spot' was thought to be
about the size of Earth and, like the
Red Spot, a storm that had a life of its
own and rotated in the opposite direction to the planet.
Another feature was nicknamed the
`Scooter'
a small wispy cloud that rotates around the planet faster than other
clouds. There appears to be a large
amount of cloud in the upper atmosphere that, because of their shape and
size, scientists equate to cumulus clouds
on Earth.
Neptune is racked by the fastest winds
measured in the solar system
winds
travelling at nearly supersonic speeds,
even in Neptune's dense atmosphere. It
was also found that Neptune has a magnetic field which is tilted 50° from the
planet's rotation axis and is offset
10,000 kilometres from the planet's centre.
Neptune is cloaked by a hazy upper
layer (like smog). Under this thick atmosphere, Neptune is thought to have a
`melted' ocean of ice which lies over a
rocky core, and a temperature of minus
-
-
180°C.
Comprising mainly hydrogen and
methane, Neptune was found to have
aurorae ií1 its upper atmosphere, and
faint radio emissions were recorded by
the spacecraft.
Once Voyager had made the close encounter and discovered another two
moons, 1989N5 and 1989N6, it discovered that instead of only have incomplete ring arcs around it, Neptune also
had a system of three complete rings.
Both the rings and ring arcs are thought
to be made up of small dust particles.
Five hours after the main encounter
with Neptune, Triton was encountered
and, as spectacular as Neptune was,
Triton completely stole the show. Triton
is an incredible contradiction of geological activity, which left scientists both ecstatic and stunned. Slightly smaller than
our moon, it showed ancient ice volcanoes, quake faults, cliffs, glacier-like
terrain and swamps of ice mush methane. The moon has the coldest temperature in the solar system, at minus
245°C, and is the third body in the solar
system with a system of volcanoes (the
other two are Earth and Jupiter's moon
-
-
year 2020, Voyager 2 can rightfully be
called one of the greatest exploration
journeys undertaken by man, and long
after all of us are gone, it will still be
drifting on an unending path.
There has been much written about
the Voyager spacecraft and their discoveries, summed up by Dr Edward Stone,
Voyager's chief scientist, in a quote by
T.S. Elliot:
Neptune and its large moon Triton as
2 on May 9,
1988, using the clear and green
narrow angle filters. The planet
appears
bluish -green
because
methane in the atmosphere absorbs
red wavelengths.
pictured by Voyager
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"Not farewell, but fareforward, Voya-
Io).
When images were returned
after the main flyby, scientists were
amazed to see the eruption of a volcano, spewing frozen methane and hydrogen five miles high. Careful examination
of Triton's surface showed that there is
an abundance of volcanic activity with
the surface pockmarked with craters,
some of which showed recent activity.
Post encounter activities consisted primarily of observations of Neptune's
dark side and the sending back of recorded data to Earth. This phase was
completed on October 2.
Voyager, now renamed the Voyager
Interstellar Mission (VIM), is now well
on its way to the boundary of the
known solar system. In May, most of its
instruments shut down to conserve energy, but not before the spacecraft turned
around towards the Sun to take a
photograph of the solar system
an
image which will surely be spectacular.
Voyager has no set destination, but
scientists at JPL have calculated that, if
it continued on its present path, it
would encounter the star Sirius in the
year 296,036
from a distance of 432
light years.
Expected to run out of fuel by the
a
month
gers".
READER INFO NO. 44
ELECTRONICS Australia, August 1990
173
Aussie CAD Software Review:
Prole Is
$c;ematIc V3.3
previous issues, we've reviewed both the 'top of the range' and 'economy' PCB layout
packages from pioneering Tasmanian software firm Protel Technology. Here's a report on the
latest version of their matching package for drawing circuit schematics.
In
by JIM ROWE
Back in the September 1989 issue,'
you may recall, we published a double
review of Protel's `Autotrax' professional PCB layout package, by Peter
Phillips and Mark Cheeseman. Then in
the following December issue, we published Tom Moffat's review of the firm's
revamped economy PCB layout package, dubbed `Easytrax'.
Our reviewers found both of these
packages very convenient to use, and
capable of producing highly professional
results. In fact they were so impressed
that based on their reactions, we've
been using Autotrax in particular, here
in the EA office ever since, to produce
the PCB designs for many of our projects.
As with all CAD packages, there's an
inevitable learning curve. Our first PC
board designs took rather longer than if
we'd used the familiar old tape-and donut system, but it didn't take too long
before we became familiar enough with
Autotrax to be able to drive it quickly
and efficiently. And we've been very
happy with the results.
It's understandable that based on this
experience, we were also keen to try
out the latest version of Protel's matching Schematic `capture' package
Version 3.3. Happily an opportunity to do
this came a couple of months ago.
We've been using it ever since, and
some of the products of our trials have
already appeared in the magazine. The
article that follows is a summary of our
experiences and findings to date.
-
The package
Like the matching PCB design packProtel Schematic is designed to
run on IBM PC/XT/AT and PS/2 Series
machines and close compatibles. It will
run on a twin floppy system, but operation is faster and more efficient when
it's installed on a hard disk. Similarly
ages,
174
best results are achieved with an EGA
or VGA colour graphics adapter and
matching colour monitor, although it
can be used with a monochrome adapin fact it's somewhat less
ter/monitor
dependent upon colour than Autotrax
and Easytrax.
A Microsoft or compatible mouse is
recommended for faster and more convenient operation, but like the PCB
packages Schematic can be used without
a mouse if you don't have one. In fact
for some operations, the keyboard is almost as convenient as the mouse; more
about this later.
Schematic 3.3 will run happily in a
system with 640K of conventional
memory, but the maximum size of a
schematic file is limited to about 200K
or so, depending upon the number of
TSR's (memory resident utility programs) present. This means that for
handling larger schematics, you may
need to remove TSR's (like Sidekick,
etc).
The package can make limited use of
LIM 4.0 type EMS (expanded) memory, if this is available
but only for
holding its overlays. This gives faster
operation, but still doesn't allow handling larger schematic files; the only
real way to do this is by breaking them
up into separate subsections.
The physical Schematic 3.3 package
comes as six 5.25" 360K floppy disks
and a ring binder reference manual.
Earlier versions included copy protection, and came with a hardware `dongle'
which had to be plugged into one of the
parallel printer ports, before the main
programs would run. But Protel has
now removed the protection, so the
dongle is no longer needed.
In terms of software the package consists of seven functionally separate and
complementary programs. The main
three consist of Schedit, the actual sche-
ELECTRONICS Australia. August 1990
-
-
matic entry and. editing program;
Schplot, the program which prints out
or plots the resulting schematic files;
and SLM or `Schematic Library Manager', a program which lets you modify
or create schematic symbol libraries.
Then there are four utility programs:
Post, which processes a schematic file to
produce a netlist for PCB routing, a
wirelist (presenting the netlist in human readable form), a report of any errors
found in the netlist, and a `BOM' or bill
of materials; Netcheck, which can compare two netlists and report any differences; Nettran, which can convert a
Protel netlist file into other formats (including Racal, Cadnetix, P -CAD, Calay
and Computervision); and Annotate,
which can process a multi -sheet schematic file so that all components are
renumbered into consecutive order.
All three of the main programs have a
graphical -type user interface, with easy
to use pop -down menus. However as
with the PCB design programs, they're
also designed so that once you're familiar with program operation, you can
speed things up considerably by using
keyboard `shorthand'. More about this
later, too.
Four of the six disks supplied in the
package contain the programs just described, plus device drivers, while the
remaining two disks contain some 17
different predesigned schematic symbol
`libraries'. These cover all sorts of
things from basic discrete components,
through standard op -amps and comparators, TTL and CMOS. logic devices, to
memory devices and microprocessors. A
very wide variety of standard device
symbols, in fact
plenty to get almost
anyone going, and probably sufficient
for even the long-term needs of many
-
users.
As with many of the latest software
packages, Schematic 3.3 comes with an
C2
T
IC1
3
TL071
R3
r-
ik
6
I
47nF
3
'Cl
TLe71
6
+
C2
47nF
ik
M1
Mi
0-100uA
e-1seuA
R4
VR1
,ZERO
R4
VRl
1.5k
100k
1.5k
í88k
VR2
1k
ZERO
VR 2
ik
CALIBRATE
CALIBRATE
12
R2
1.5k
1.5k
--+
Two samples of the kind of hard -copy output produced by Protel's Schematic V3.3, reproduced here actual size so you
can evaluate the resolution. At left is the quality from a TI `MicroLaser' 300dpi printer; at right that from a Roland
DXY-980A plotter. In each case the main factor limiting resolution appears to be that of the software package itself,
which is fixed at about 100dpi for the bit -mapped component symbols.
extensive collection of driver routines to
As with other schematic drawing
customise it for use with a variety of packages, you build up a schematic with
different video adaptors, printers and Schedit by calling up the component
plotters. There are drivers for some 15 symbols you need from a library, giving
different video adaptors
from Her- them designations (R5, C17 etc) and
cules and CGA through EGA to VGA
values, and placing them in the desired
and various `special' types. Similarly positions. Then you link them according
there are 14 printer and plotter drivers,
to the circuit, using connection lines and
covering most common types of printer junction `blobs'. Connectors, connecfrom Epson MX/FX80 to HP Think - tions to ground and supply rails, cojet and Laserjet, as well as a variety of axial cable symbols and so on are
popular plotters such as those from HP, treated in very much the same way as
Roland and Calcomp.
normal component symbols
in fact as
In short, like the PCB design packfar as Schedit is concerned, there's virages Schematic is capable of working
tually no difference.
with a very wide range of standard
Up to three component libraries can
hardware configurations.
be opened at any one time, while you're
building a schematic. In placing a component you're not restricted to its liIn operation
brary orientation; you can easily rotate
Installing Schematic 3.3 on your sys- it in 90° steps, as desired. You can also
tem is very straightforward. It's simply a
`flip' or mirror -image reverse it, in eimatter of creating directories for the ther the horizontal or vertical axes
program and schematic files, and then
very handy for things like transistors
copying across the programs to the forand op -amps. These functions are permer directory from the master disks.
formed very quickly, using one or two
The final step is typing in the name of keystrokes.
your video adaptor, whereupon an apPlacing a component, line, junction or
propriate batch file copies in the corre- text annotation using the mouse is very
sponding driver. Then yoti're ready to
straightforward. You simply click the
run.
left mouse button to get the main
The program you tend to use most of
menu; pull down the highlight bar to
the time is Schedit, of course. This is
'Place' and click again, causing the
the actual input and editing program,
Place menu to appear; then pull down
after all.
the highlight. bar again to the appropri-
-
-
-
-
-
ate item
Component, Line, Junction,
Text or whatever.
If you're placing lines or junctions,
this is all that is involved apart from
using the mouse to locate the start and
finish of each line or line segment, or
the junction locations. With component
placement there are further steps,
where you select either the last type of
component placed (offered by default
which can be handy), or select first a library and then the desired component
from it. Then Schedit calls up the symbol, and prompts you for a designation
and value, before finally letting you
guide it in placing it on the screen schematic, in the desired position and with
the desired orientation.
It's all rather simpler to do than this
description might suggest, and some::hªt faster. However once you get the
-
hang of things you can speed them up
even further, by using the keyboard
`shorthand' facility. This lets you bypass
some of the menues, by simply typing
letter sequences: 'PC' for placing a com-
ponent, 'PL' for placing a line, 'PJ' for
placing a component, and so on.
The same applies for the various schematic editing functions provided by
Schedit. For example to delete a component, you can either click through the
menues with the mouse, or simply type
'DC'
before indicating the component, of course! Similarly to move a
-
ELECTRONICS Australia, August 1990
175
Protel Schematic
component you type `MC', and so on.
As this suggests, there's a full range
of entry and editing facilities. You also
have a choice of line weights (4) and
junction sizes, along with a choice of 10
different paper sheet sizes (A4 A0, A
E) on which the schematic is to be
drawn.
Nice features of Schedit include an
Undelete facility, to reverse the last
deletion in cases where it has been accidental; the ability to Zoom up and
down, to check the overall look of a
schematic as well as adjusting the fine
details; the ability to customise the
screen colours; a key macro facility, allowing you to program the function
keys with frequently -used keystroke
macros.
There's also an Options setting facility, allowing you to do things like enable/disable auto screen panning, adjust
the time between Schedit's automatic
file backups, turn the 'snap to grid' facility on or off, turn the sheet border
and title block on or off, select the cursor shape and whether or not you want
it to flash, and so on.
Another powerful and handy feature
is a block manipulation facility, which
allows you to `define' a particular section of the schematic and perform various operations with it. These include
moving it to another place, copying it,
deleting it, deleting everything except it,
or writing to disk. A block can also be
read back from disk, and placed on the
schematic rather like a component.
Of course complete schematics can
also easily be saved to disk, and recalled at any time to edit or expand
them.
Having used Schedit to create your
desired schematic as a disk file, the next
step is to use Schplot to produce the
corresponding 'hard copy' on paper.
Schplot employs the same system of
pop-down menues, and is again very
easy to use. Essentially you specify the
schematic file you wish it to load, then
specify the various print or plot options
and parameters, and finally tell it to either print or plot.
Schplot includes a Setup mode, allowing you to do things like select custom
screen menu colours, configure the
serial ports, select a printer or plotter
driver, and so on. In the case of plotters
you can specify the number of pens, the
plotting scale, the X and Y offsets (if
any), the orientation, the port it's connected to, the pen speed and so on.
There's a similar set of choices for
printers.
-
-
-
176
Whether you're plotting or printing
the schematic, during the actual operation Schplot displays a data screen
showing progress. A nice feature, since
the processing can take a few minutes
with a reasonably complex schematic...
Incidentally, as with the PCB design
packages Schplot can also plot or print
to a disk file, rather than directly to a
plotter or printer. This allows you to
use plot file translation programs to further process the files, if desired. An example would be Insight Development
Corp's 'PrintAPlot' program, which can
take an HPGL plot file and print it out
on a normal 9 -pin dot matrix printer
with surprisingly good quality.
Schedit and Schplot are the two main
programs in the Schematic package, and
those that are normally used for most of
the time. In fact if you don't use any
esoteric devices and you're happy with
the schematic symbols supplied in Schematic's various library files, you may
well not need to use any of the other
unless perhaps you want to
programs
produce netlists for Autotrax, or Bills of
Materials for manufacturing. I imagine
this might apply for a significant proportion of Schematic users.
However at least some users will either want to modify some of the symbols in the supplied libraries, to suit
their house style or personal preferences, or else need to create additional
symbols for special components. It's for
situations like these that Protel has supplied SLM, the `Schematic Library
Manager' program.
Earlier versions of Schematic used
text -based files for each schematic symbol, and these were created and/or
modified using a word processor or text
editor program. However with version 3
Protel changed to a rather easier graphics -based file format, with its own
graphics editor to allow symbol creation
and editing directly on the screen: SLM.
Like Schedit and Schplot , SLM has a
fully graphical user interface with pop down menues and cursor control of
symbol editing. However it also allows
the original method of text -based file
editing if desired, for those happier with
it from earlier versions.
Schematic actually uses two different
types of schematic symbol, the so-called
`Block' and `Bitmap' types. The Block
type is based on a simple rectangular
box symbol, with the required number
of terminal pins, as used by the majority of MSI and larger digital integrated circuits. In contrast the Bitmap
type is used for most discrete components and analog IC's, which need a
more elaborate basic symbol.
ELECTRONICS Australia, August 1990
-
-
SLM allows creation and editing of
both types of symbol. Using it you can
either begin a new library, or call up an
existing library, and either create new
component symbols or edit existing
symbols. You can also re -sort the components of a library you have edited, to
bring them back into alphabetical order
of names.
During editing, SLM lets you specify
or change the size of the component,
specify or change the number of connection pins, move the pins, specify or
change the symbol bitmap as desired,
and so on. And while you're creating or
editing a bitmap, it makes things easier
with functions to draw both straight
as well as basic
lines and circles/arcs
functions to allow plotting or deletion of
individual pixels. There's also a `fill'
function, to speed up the creation of
filled -in areas of the symbol.
Other facilities provided by SLM include the ability to base a new component's bitmap on that of an existing
component bitmap, to add another component's bitmap into the bitmap of the
symbol currently being edited, and to
create multi -symbol components (such
as the A, B, C and D parts of a quad
op -amp device). In short, it's a very
powerful tool for creating and edítíng
component schematic symbols.
The remaining programs that make up
the Schematic package are somewhat
simpler in both function and operation,
and have a text -interface format. As described in the Schematic user manual,
they're much more in the nature of useful utilities, rather than primary programs.
-
In
practice
Having now used the Schematic 3.3
programs fairly extensively over the last
few months, we're hopefully in a reasonable position to give a verdict on
both their ease of use and performance.
And in general, I believe it's true to say
with the
that we're very impressed
package as a whole, and especially with
the main programs Schedit and Schplot
These are both very easy and intuitive
to drive, and make schematic creation,
editing and printing/plotting surprisingly
easy.
These two main programs in particular are basically fine, and Protel can be
justly proud of their achievement.
Things we've found particularly nice
about Schedit are the way it remembers
the last component you've placed, and
suggests this as a default if you go to
great for speedy placeplace another
ment of a number of common components; the way you can use both key -
-
.
-
stroke `shorthand' and mouse control,
for really fast operation; the way it lets
you move components, lines and junctions readily; the way it lets you move
component labels, relative to their symbol, to produce a tidier schematic; the
degree of control it gives you over symbol orientation, as well as placement
location; the way it automatically increments the default component designation, for repeated placements; and the
way it also offers the last value as a devery handy where you're placing
fault
a series of 100k resistors, or a gaggle of
0.1uF bypass caps.
Similarly Schplot has some nice features, including the way it remembers
your preferred printer and plotter options, along with your screen colours
and whether or not you like to print/ plot the sheet border and/or title block;
the way it allows you to specify the desired X and Y offsets; and the way it
lets you set the number of plotter pens
used, along with their speed.
-
We also like the way it will work with
a wide variety of printers and plotters;
so far we've been able to try it with two
different 9-pin dot matrix printers, a
Roland DXY-980A plotter and a Texas
Instruments MicroLaser. We've also
tried using Schplot to produce HPGL
plot files on disk, and then getting
IDC's PrintAPlot to convert them for
printing on a dot-matrix printer. This is
fairly slow, but certainly gives the best
results if you only have a cheap 9 -pin
printer.
I have to say, though, that we have
found a few things to grizzle about. One
is that although Schedit does suggest the
last component placed as a default,
when you want to place again, it doesn't
suggest the library from which it came
as a default, if you indicate that you
wish to place something else; instead
you have to nominate one of the three
active libraries all over again. It would
speed things up a bit, if it offered the
current library first
as this will often
be the most likely choice.
Perhaps more serious is the fact that
the printing/plotting
of
resolution
Schplot is fixed at about 100dpi, especially for the bit -mapped 'component
symbols. This means that some of these
symbols plot or print out with clearly
visible `staircasing' of oblique lines and
curves even when you're using a plotter or 300dpi laser printer. This is a little disappointing when its sister PCB
design package Autotrax will print out
beautifully sharp and clean 300dpi artwork, if you have a suitable printer...
Another little gripe about the Schedit
and Schplot combination is the limited
-
-
This
is a bit of
This is in apt type
text
in
10 p t type
This is in 16pt type
This is 2Opt type
choice of text fonts for component
labels and text annotations. Basically
there are only two, regardless of the
type of printer or plotter you're using,
and chosen purely on the basis of size.
For the smallest of the four available
sizes (8pt) you get a fairly ugly and hard
to read sans -serif font rather like that
found on cheap 8-pin dot matrix printers; for the other three sizes (10, 16 and
2Opt) you get an even uglier and harder
to read serif font.
Frankly in our view it would be better
to have one clean and easy to read sansserif font like Helvetica, in all sizes.
We found a few problems with SLM,
too. The most obvious shortcoming is
that it seems to do an excessive amount
of 'disk thrashing'
accessing the hard
disk much more than seems necessary.
Frankly, it seems to load library files
from the disk over and over again, apparently unable to remember that it already has them loaded into the memory
workspace.
It loads the library you want to edit at
the start of editing, and also immediately after saving it at the end of a session; then if you indicate straight away
that you want to edit another symbol
from the same library, it'll load it again!
If you want to copy a symbol file from
another library, it will load that too; but
if you next want to copy another symbol
from the same library, it'll load it all
over again...
Somehow, SLM doesn't seem to keep
the same track of its existing opened
files, in the same way as is done by
Schedit and Schplot. It also has a few
little bugs still present, which mainly
show up as a tendency to corrupt its 'bit
map size' records, when you perform
various symbol editing operations. This
happened to us a number of times while
we were trying to create an 'EA style'
symbol library, in some cases causing
system crashes next time we tried to
load one of the symbols which had become corrupted. Nasty!
A minor criticism of 'SLM is that
when you're in bit -map editing mode
and you call up the arc -drawing function
to produce a circle or arc, it tells you to
`Select arc starting point'. In fact it's
really asking for you to indicate the centre of the circle or arc's radii
a little
misleading.
We contacted Protel Technology's
software support manager Bruce Ed -
-
-
Here are the text
fonts provided by
the package.
Frankly, we'd
prefer a plain
sans -serif font,
like Helvetica...
wards about these shortcomings and
problems, and he was very helpful. The
company is very much aware of the
100dpi
resolution
limitation
with
Schplot, and is working on a new version which will provide full vector
graphics as used in Autotrax. But unfortunately this is a fairly major revamp,
and like so many pioneering Aussie
firms they're not over -endowed with resources so it may be a little while before the new version is ready.
Similarly they're aware that SLM still
has a few flaky aspects, including its intermittent file corruption problems. The
bugs responsible are proving extrémely
elusive to track down, but in the meantime they've found that a practical
remedy is to force SLM to re-save the
currently open library after editing each
symbol
rather than editing a number
of them before saving.
In the meantime they've decided to
do a complete revamp of the symbol
editing routines, and possibly build
them directly into Schedit
-
-
.
Summarising
On the whole, we're very impressed
with the Schematic 3.3 package. It's a
very practical and easy to use CAD
package for drawing circuit schematics,
using reasonably -priced MS-DOS PC's.
And it gives very professional -looking
results, at a price ($995) that compares
well with others that are available.
The fact that it still has a few little
shortcomings is basically disappointing
only because the package as a whole is
of such a high standard. If the folks at
Protel can fix them for the next version
of Schematic, they're going to have a
really outstanding world -class package.
When this happens, I certainly hope
they give us the opportunity to try it
out. In the meantime, I'm proposing to
keep using version 3.3
despite its
blemishes. So don't be surprised to see
a few `Schematic schematics' .in the
magazine...
Like the other Protel CAD packages,
Schematic 3.3 is available through many
software dealers and CAD specialists.
However if you have any difficulties in
tracking down your nearest dealer,
Protel Technology is at Technopark
Dowsing Point, Hobart 7010 (GPO Box
204, Hobart 7001) or phone (002)
73 0100.
m
-
ELECTRONICS Australia, August 1990
177
EA
Directory of suppliers
Which of our many advertisers is most likely to be able to sell you that special
component, instrument, kit or tool? It's not always easy to decide, because
they can't advertise all of their product lines each month. Also some are
wholesalers and don't sell to the public. The table below is published as a
special service to EA reades, as a guide to the main products sold by our retail
advertisers. For address information see the advertisements in this or other
recent issues.
Supplier
State
All Electronic Components
Vic
Altronics
Acetronics
Dick Smith Electronics
Electronic Brokers
Electronic Component Shop
Emona Instruments
Geoff Wood Electronics
George Brown Group
Jaycar Electronics
Pre-Pak Electronics
Preston Electronics
RCS Radio
Rod Irving Electronics
Scientific Devices
Sheridan Electronics
Tandy Electronics
Wagner Electronics
WA,NSW
NSW
A
BCDEFG
All
Vic
Vic
NSW
NSW
All
Eastern
NSW
Vic
NSW
Vic
Vic
NSW
All
NSW
D Components
KEY TO CODING
E IC chips & semiconductors
A Kits & modules
F Test & measuring instruments
B Tools
G Reference books
C PC boards and sup plies
Note that the above list is based on our understanding of the products sold by
the firms concerned. If there are any errors or omissions, please let us know.
Electronics Australia Reader Services
"Electronics Australia" provides the following services:
Subscriptions: All subscription enquiries should be directed to:
Subscriptions Department. Federal Publishing Co. PO Box 227.
Waterloo 2017. Phone: (112) 693 6666
BACK ISSUES: Available only until stocks arc exhausted. Price:
$4.50
PHOTOSTAT COPIES: When hack issues are exhausted,
photocopies of articles can be supplied. Price: 54.50 per project
or 19 where a project spreads over several issues.
PUB PATTERNS: High contrast. actual size transparencies for
printed circuit boards and front panels are available. Price: 15 for
boards up to 1110 square centimetres: 110 for larger boards. Please
specify positive or negative.
PROJECT QUERIES: Advice on projects is limited to postal
correspondence only, and to projects less than five years old.
Price: SS. Please note that we cannot undertake special research
or advise on project modifications. Members of our technical staff
are not available to discuss technical problems by telephone.
OTIIER QUERIES: Technical queries outside the scope of
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the "Information Centre" pages at the discretion of the Editor.
PAYMENT: Must he negotiable in Australia and made payable to
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ELECTRONICS Australia. August 1990
ADVERTISING
INDEX
Acetronics
161
All Electronic Components
159
Altronics
133-137
Audio 2000
ETI 35
AVO Electronics
132
Awesome Technologies
126
Capital Computers
17
Circuit Works
148
Data Electronics
173
David Hall Electronics
148
Dick Smith Electronics
18,52-57
EA subscriptions offer
18-19
EEM Electronics
161
Electronic Component Shop
143
Elmeasco
43,144
Emona Instruments
127
Emtronics
ETI 23
Federal Marketing
162-163
Geoff Wood Electronics
145
Hagemeyer
ETI 39
Hi -Corn Unitronics
ETI 17
Hycal Instruments
161
Hy-Q International
159
Icom Australia
61
Jaycar
116-119
John Ferella
161
Kalex Electronics
142
Kenelec
35
Leading Edge Audio
ETI 33
Legendary Loudspeakers
ETI 28
Maestro Distributors
161,ETI 18
Newtronics
161
Obiat
IBC
Peter Lacey Services
46
Philips Components
IFC,65,67,69
Philips S&I
OBC
Pioneer Marketing
70
Program Dev. Services
ETI 8
Prometheus Software
16
Protel Technology
ETI 16
RCS Cadcentres
ETI 13
RCS Radio
Rod Irving Electronics
RVB Products
Scientific Devices
SETEC
SME Systems
Stotts Correspondence
Stover Electronics
Technical Imports
Transformer Rewinds
Westinghouse Systems
Wireless Institute of Aust.
Yamaha Music Australia
161
26-31,150-151
154
ETI 20
149
ETI 19
45
13
ETI 20
161
ETI 2,19
155
9
This index Is provided as an additional service.
The publisher does not assume any liability for errors or omissions.
OBIATLTD YOUR ONE STOP
DISTRIBUTOR OF.
TEST & MEASURING INSTRUMENTS
With 2 multifunction displays and
capabilities, the Fluke 45 does
virtually everything you want a
meter to do...
at a suprisingly affordable price
from $1216 ex tax $1417 inc tax
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including
Low cost 70 Series
accuracy
0.05% basic do current
accuracy
1MHz frequency counter
RS -232 Interface standard
dB with 21 reference
impedances and audio
power calculations
Compare and Relative
functions
Min/Max and Touch-HoldT"'
functions
Optional PC software for
RS -232 applications
Optional IEEE -488.2
interface, battery pack
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Closed Case Calibration
Dual Display
True rms voltage and
current including ac+dc
0.02% basic dc voltage
16 different measurement
®OfO:O (p,.
stock a full range
of Fluke Multimeters
for all requirements
Five digit 100.000 count
,
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Analog bar graph
10A range
3200 count
Touch Hold"' (77)
Top of the Line
80 Series
Min/Max/Average
Selectable response times
lms peak hold (87)
Extra functions capacitance, frequency etc
Full Range of
Accessories
and RF Probes
Current Guns
Temperature
Cases
HV
FLUKE
Made in U.S.A.
Fluke Multimeters from $150 ex tax & Accessories ex-stock
Now distributing
SILVERTRONIC
Test Leads and
Black*Star
'
Quality British Made Counters...
...at Very Affordable Prices
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<±lOppm -10°C to +70°C
External Timebase
Single & Multiple Average
Period
8 1/2 Digit LCD Display
AGC 20MHz Range
Display Hold & Reset
Count
Queensland enquiries for Blackstar
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Express delivery throughout
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<5mV Sensitivity at 10MHz
o.1Hz max Resolution
Mains/Rechargeable Battery
Operation
<± l Oppm -10°C to +70°C
Trigger Level Control
0.1. 1. lOs Gate Times
8 Digit Bright LED Displays
Optional ±lppm TCXO
---,--
b-_c'y170.OD0
'1-41ii'trs:_+
quality, here's the answer Universal Deluxe Multimeter
Lead Kit has croe clips, spring
hooks. spade terminals etc
$40 (ex tax) $46 (inc tax)
100MHz Scope Probe Kit
xl/x10 switched $43 (ex tax)
$50 (Inc tax)
250MHz Scope Probe Kit
xl/x10 switched $48 (ex tax)
$56 (inc tax)
Meteor Frequency
Counters
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If you're looking for high
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Full Signal Conditioning
8 Digit Bright LED Displays
0.1, 1. lOs Gate Times
Optional ±lppm TCXO
Frequency Multiplier
Scope Probes
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Safety Fused Test Lead Set
Fuse holder in each lead.
Includes insulated croe clips.
$65 (ex tax) $75 (inc Tax)
Prices from $295 (ex tax) $340 (Inc tax)
to $1075 (ex tax) $1240 (Inc tax). Ask for catalogue.
Detailed brochures and specifications available. We are factory trained to advise
on your requirements for general purpose Test It Measuring Instruments
Ask for our FREE 16 page
Shortform Catalogue
00] 03ZZTC
T"IrYr
=12
129 Queen Street, Beaconsfield P.O.Box 37 Beaconsfield NSW 2014
Tel
(02) 698 4776 Telex
:
:
AA71958 Fax
:
(02) 699 9170
0456
OLD Electra Technical Systems Old, Tel (07) 356 2699, Fax (07) 356
W.A. : Leda Electron(cs,Tel (09)361 7821, Fax (09) 470 4641
:
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W.IC.T. be,.
VISA
Master:
READER INFO NO.
45
FLUKE AND PHILIPS - THE GLOBAL ALLIANCE
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TEST
&
MEASUREMENT
FLUKE
PHILIPS
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The new Fluke 45 has dual display versatility.
With 2 multifunction
displays and 16 different measurement
capabilities, the new
Fluke 45 does virtually everything you
want a meter to do.
And for a surprisingly
affordable price.
FLUKE
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Get everything
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The 5 -digit, 100,000 count dual displays give you more information in less
time
and with less effort. For example,
measure the VDC output of a power supply while measuring the VAC ripple. Or
check the amplitude and frequency of an
AC signal. From a single test connection!
And the Fluke 45 is designed to make
complex measurements easier, with standard features like a 1 MHz frequency
counter, Min Max, limits testing (Hi/Lo/
Pass), Touch Hold® and Relative modes.
There are 21 different reference impedances for dB measurements; in the 2 c
to 16 n ranges, audio power can be
automatically displayed in watts.
-
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interface and rechargeable batteries are available as options.
45 A...
(-«a(0-W11
you've ever wanted.
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For all the information on the new Fluke
45, contact your local
distributor.
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Accuracy to get the job done right.
The Fluke 45 is a true-rms meter,
FLUKE 45 DUAL DISPLAY MULTIMETER
Dual Display
Compare and Relative functions
with 0.02% basic do voltage accuracy
and 100,000 count resolution on both
displays. Basic dc current accuracy is
0.05%, making the 45 ideal for servicing
4-20 mA current loops. Closed -case
calibration simplifies the calibration
process and increases uptime.
True-rms voltage and current,
including ac+dc
Min Max and Touch Hold`
0.02% basic dc voltage accuracy
0.05% basic dc current accuracy
Optional PC software for RS -232
Even an RS -232 interface is standard.
Connecting the Fluke 45 to PCs,
RS -232 printers and modems is as easy
as attaching the cable. An IEEE -488.2
1
MHz frequency counter
RS -232 interlace standard
dB, with 21 reference
impedances, and audio power
calculations
functions
applications
Optional IEEE -488.2 interface,
battery pack
One year warranty
READER INFO No. 46
For Further Information Contact Your Local Philips Test & Measurement Organisation: Sydney (02) 888 0416, Brisbane
(07) 844 0191, Melbourne (03) 881 3666, Adelaide (08) 348 2888, Perth (09) 277 4199, Auckland (09) 39 4160, Wellington (04) 88 9788.