Electronics Australia Reader Services

111
9 312966 123633
r
1414VQE
We came to
Australia in
August and
set new
standards of
value and
support for
14.4
modems.
High-speed desktop fax modem
V32bis (14.4 kps) data and fax modem.
Includes serial cable (9 or 25 pin computer connection).
Extra-length (4.5m) phone cable.
Error correction (MNP4N.42) and data compression
(MNP5N.42bis).
Compatible with all industry-standard fax and
communication programs.
Port speeds up to 57.6 kbps.
We must
have done
something
right •••
thousands
have beed
sold.
Our Voice and
V.34 products
will follow in
the pattern
set by the
V.32bis
models.
Exceptional
value.
1414VQH
High-speed
IBM card fax modem
V.32bis (14.4 kps) data and fax modem.
Extra length (4.5m) phone cable.
Configurable as COMI-COM4.
Error correction (MNP4N.42) and data compression
(MNP5N.42bis).
Compatible with all industry-standard fax and
communication programs.
Port speeds up to 57.6 kbps.
\
Volume 57, No.2
February 1995
Hi-tech in a modern cinema
Video and Audio
6 WHAT'S NEW IN VIDEO & AUDIO New 'Classic' seriesfromDuntech
8 THE CHALLIS REPORT Accusound's 'Phase Zero' loudspeaker system ...
16 APPLE'S QUICKTAKE DIGITAL CAMERA Connects to your computer!
Features
14 MOFFAT'S MADHOUSE Reflections on the 'Quackintosh'
18 THE WORLD'S BIGGEST TELESCOPE
Electronics and computer control
have brought about dramatic changes
inside the projection box of modern
'multiplex' cinemas. Projectionist Reg
Leahy explains how it all works, in his
article starting on page 20 ...
Interactive satellite TV
The ESO's Very Large Telescope
20 HIGH TECH IN A MODERN CINEMA Inside a modern 'multiplex' bio box
26 CSIRO'S MULTIBEAM SATELLITE ANTENNA One dish, many 'birds'. ..
32 VICTORIA'S SCHOOLS LINKED BY SATELLITE Interactive TV education
34
48
WHEN I THINK BACK... Archie Caswell, radio dealer and modest hero - 2
OUT BEYOND THE SOUND CARDS Kawai's 'outboard' MIDI synthesisers
Projects and Technical
44 THE SERVICEMAN The Sanyo CTV that I almost put an axe through!
56 VERSATILE SOLID STATE AUDIO RECORDER Replays clips on demand
64 DSE 'DISCOVERY SERIES' KIT: Simple IOHz - IOOkllzfanction generator
68 NEW STEREO TV SOUND RECEIVER - 2 Construction, testing & alignment
80 CIRCUIT & DESIGN IDEAS Simple LED display driver, DTMF decoder
82 AUTOMATIC HOUSE NUMBER 'Jumbo' LED displays glow only at night ...
90 EXPERIMENTING WITH ELECTRONICS Playing games with the 4060
98 VINTAGE RADIO Good advice for vintage set buyers: 'Caveat Emptor'
Professional Electronics
Victoria's schools are now able to
offer both students and teachers the
benefits of interactive satellite TV
training, via the state's ISTV network. Melbourne Satellites installed
many of the terminals, and also three
systems for the Army's College of
TAFE in Bonegilla - see page 32.
On the cover
The upper photo shows Bob Parker's
novel VMAC module, which lets you
record up to eight short messages
and play any one back in response to
a digital signal (see page 56). Also
shown is Paris Radio's automatic
house number project (see page 82).
Photos by Ben Granger.
106
110
116
120
122
NEWS HIGHLIGHTS Mitec microwave equipment for Australian pay-TV viaMDS
PC-BASED SERIAL PROTOCOL ANALYSER Put that spare PC to work!
NEW PRODUCTS Fibre optic modem, RF signal generator, parallel port tester
SOLID STATE UPDATE Transparent SIP photodiodelamplifier, SMT regulators
SILICON VALLEY NEWSLETTER Multimedia rules at Comdex 94 ...
126 COMPUTER NEWS & NEW PRODUCTS Computer controlled robotics kit
Columns and Comments
4 LETTERS TO THE EDITOR Kingsley Radio, Commodore computer update
5 EDITORIAL VIEWPOINT Hobby enthusiasts make the best engineers!
40 FORUM TETIA and qualifications for service technicians: the debate continues
85 SHORTWAVE LISTENING More interesting summer listening
94 INFORMATION CENTRE Fuses, baluns and electrically charged rain ...
Departments
93
$00K REVIEWS
102 MARKETPLACE
104 l;A HISTORY, CROSSWORD
130 DIRECTORY OF SUPPLIERS
130 ADVERTISING INDEX
97 NOTES AND ERRATA
ELECTRONICS Australia, February 1995
3
MANAGING EDITOR
Jamieson Rowe, B.A., B.Sc., SMIREE, VK2ZLO
GRAPHICS/PRODUCTION EDITOR
Mille Godden
TECHNICAL EDITOR
Rob Evans, CET (RMIT)
PROJECT DESIGNER/WRITER
Graham Cattley
CONTRIBUTORS
Louis Challis
Arthur Cushen, MBE
Peter Lankshear
Jim Lawler, MTETIA
Tom Moffat, VKTTM
Peter Phillips, B.Ed., Dip Ed., ECC
Nick de Vries, MIAME, AMSAE
Neville Williams, FIREE, VK2XV
DRAFTING
Drawquick Computer Graphics
COVER DESIGNER
Clive Davis
PRODUCTION
Ray Eirth
CIRCULATION MANAGER
Michael Prior
PUBLISHER
Michael Hannan
ADVERTISING MANAGER
Selwyn Sayers
Phone (02) 353 0734; fax (02) 353 0613.
ADVERTISING PRODUCTION
Karla Dixon, phone (02) 353 0713
SECRETARY
Anna Maria Zamora
HEAD OFRCE - EDITORIAL
P.O. Box 199, Alexandria 2015.
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Phone: (02) 353 0620. Fax: (02) 353 0613
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Subacrlptlons enqulrlee: phone (02) 353 9992
Book Shop enquiries: phone (02) 353 9944
INTERSTATE ADVERTISING OFRCES
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Fax: (07) 252 3692, Graham Smith.
ADELAIDE: 98 Jervois Street, Torrensville, SA
5031. Phone: (08) 352 8666,
Fax: (08) 352 6033, Kerryn Delaney.
PERTH: Allen & Associates, 54 Havelock Street,
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Fax (09) 321 2940, Tony Allen.
UNITm KINGDOM: John Fairfax & Sons (Aust),
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ASIA: Headway Media Services Ltd, Room 2101,
Causeway Bay Centre, 15-23 Sugar Street, Hong
Kong. Phone: 516 8002,
Fax: (862) 890 4811, Adrian Batten.
ELECTRONICS AUSTRALIA is published by
Federal Publishing Company a division of
Eastern Suburbs Newspapers Partnership,
which is owned by
Genera I Newspapers Pty Ltd.
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Copyright © 1994 by Federal Publishing
Company, Sydney. All rights reserved.
No part of this publication may be reproduced
in any way without written permission from the
Publisher or the Managing Editor.
Printed by Macquarie Print, 51 - 59 Wheelers
Lane, Dubbo NSW, 2830, phone (068) 843
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Distributed by Newsagents Direct Distribution
Pty Ltd, 150 Bourke Road, Alexandria, NSW
2015; Phone: (02) 353 9911.
ISSN 1036-0212
*Recommended and maximum Australian
retail price.
The Australian Publication emblem on the front cover of
this magazine Is there to signify proudly that the
editorial content in this publication is largely produced
and edited in Australia, and that most of the advertisements herein are the products and services available
within Australia.
4
ELECTRONICS Australia, February 1995
LETTERS TO
THE EDITOR
Electronic mail
I have been a reader of your magazine
since 1982 and would like to make a suggestion concerning the 'Letters to the
Editor' section of your magazine.
How about opening an e-mail address?
With computers becoming more commonplace every day, I'm sure many of
your readers would have access to (if not
possess) some form of electronic mail
service, whether this be via CompuServe,
Oz-Email, Internet, etc.
As there is a significant delay in the
publishing process of a monthly
magazine, would not e-mail enable
readers to respond in a more timely manner to columns and articles?
On a different note, I would like to
compliment you on what is generally a
very professional and informative
magazine. Also for keeping the cover
price under that $5 'mental barrier'!
Paul Richter,
Latham, ACT.
Comment: Your point is well taken, Paul,
and you' II find an announcement on page
106 of this issue.
Kingsley Radio
I wish to take this opportunity of thanking Electronics Australia and Neville
Williams for publishing the story of
Howard Kingsley Love, of Kingsley
Radio fame where I learnt my profession.
I am pleased that I was able to make
some contribution to this.
However, I would like to supply some
corrections and additional information.
Firstly a small error crept in due to two
people with the same Christian name. At
the time of writing my story I could not
remember the name of Tom Heywood's
mate and referred to him as Laurie. At a
later date I was reminded that it was
Laurie Harris. The Laurie who came to
work in the design laboratory was Laurie
Buckingham, and Neville Williams inadvertently thought that they were one and
the same. I hope that this corrects the
record for Laurie Harris.
Belatedly I have been doing some research at the local library and Air War
Against Germany 1939-1943 by John
Herington records in part ' ...that Bardia
was captured 5th Jan. 1941' and '. .. on
14th Jan 1941 Corp. Jarvis wireless
operator and L.A.C. J. Parr of 208
Squadron were out checking radio equipment with the artillery near Tobruk:. Lost
near Tobruk:, Jarvis was filled and J.Parr
captured. He was the only British
prisoner in Tobruk:. On 22nd Jan, 1941
Jack Parr took charge of the gendarmerie
barracks in Tobruk: and held them until
the troops entered the town. He was virtually in control of local police.'
I can offer two explanations about my
reference to this happening at Bardia.
Either my memory has faltered - we are
remembering something which happened
over fifty years ago - or the information
released to the press at the time was distorted. At a suitable time I hope to view
the newspapers of the time. I wonder if
there are any RAAF 208 Squadron or
AIF 6th Division personnel who can shed
any light on this event.
I have just read the Official History of
Australia in the War of 1914-1918 Vol.
VIII Australian Flying Corps, by F.M.
Cutlack. On page 244, it states in part
' .. .in the morning of April 10th
1918 .. /Lieutenant H.K. Love of No.4
Squadron ' ... also had to land in enemy
territory, either wounded or with his
machine damaged, and was taken
prisoner. He was seen to land under control, but hit a fence, and his machine went
over on its back.' This elaborates on what
H.K. told me so many years ago and
reassures my memory a bit.
Finally, by a strange set of circumstances I have made contact with H.K. Love's
daughter Kathryn.
George Neilson, VK3TES,
Blairgowrie, Vic.
Commodore update
In the August issue's Silicon Valley
Newsletter it was mentioned that Commodore International had gone out of
business.
Although this is true, after it went into
liquidation, it was bought out by Commodore UK. Commodore International
was the division which was the most inefficient, and unfortunately, was in
charge of US distribution and advertising.
Now that Commodore UK has taken it
over, die distribution of Amiga 1200 and
4000 (with 24-bit graphics and 8-bit
sound built in) computers will continue
as will development of the new generation of Amigas based on the 'AAA' chip-
set. These will feature Motorola 68040's
and 68060's (80-100 MIPS) and in the
future, a HP RISC CPU.
David Haynie, Senior Engineer at
Commodore responsible for the new
Amigas made comments earlier this year
which indicated an aggregate bandwidth
of 400 - 600Mb/sec as far as moving data
around the system, and 16 bit sound with
eight independent voices at sampling
rates up to 64kHz. An AT&T 3210 Digital Signal Processor will be included,
enabling fantastic sound and music effects as well as high speed modem
emulation, speech recognition (built-in),
high power image processing, etc.
All this coupled with a user friendly,
Windows orientated pre-emptive multitasking Operating System (incidentally,
Amigas have had such an OS since 1985,
as well -as technological advancements
such as Local Bus), will make the
Amigas stand even further out in the
crowd of politically correct Mac's and
laboriously slow IBM compat's.
In regard to your comment about Commodore failing to cut out a niche of its
own, Amiga has quite a 'cult' following,
if you go to an Amiga user group, you
will meet some of the most devoted
people in the computer industry, many of
these people use IBM's at work and still
swear by their Amigas. Also, on the
Amiga Newsgroups on UseNET, you will
see an immense number of devoted
Amigans.
Joshua Pryor,
Belmont, NSW.
Etone speakers?
I would greatly appreciate your assistance with whatever information you can
give me in the following matter.
I am trying to get hold of an 'Etone
SW-250' subwoofer loudspeaker in good
working order. This speaker was written
up in your August 1982 (!)issue, headed
'lOOW sub-woofer speaker enclosure'.
It would appear that Etone have either
gone out of business, or been swallowed
up by somebody.
At the same time, it is difficult to image
that there wouldn't be one lying around
in Australia, or in' stock somewhere,
which its owner would be willing to part
with for a reasonable amount of money.
P. Gonda,
Linden Park, SA.
Letters publlshed In this column ex·
press ttie opinions of the correapon·
dents concerned, and do not
necessarlly reflect the opinions or
policies of the staff or publlaher of
Electronics AuatraHa. we reaerve the
rlgh~ to edit letters which are very
long or potentially defamatory.
EDITORIAL
,VIEWPOINT
!
!Hobby enthusiasts make the
best technicians and engineers!
When I was a teenager at high school, my friends and I were already keen
electronics enthusiasts. Then when I left school and was lucky enough to get a
job as an engineering trainee doing a degree course at night, most of my fellow
trainees/students and I were still building hobby projects as well, in our 'spare
time'. I can remember how strongly we competed to see who'd be first to get
their TV receiver going - it was late 1957/early 1958, and almost all of the
sets were based heavily on designs published in this. magazine, as I recall...
Many of us went on to make our careers in electronics, and I think it's
generally true to say that those who were the keenest hobby enthusiasts also
~eemed to end up as the most successful engineers. I've also found that when¢ver I've met other really successful scientists, engineers and technicians, more
often than not they've also turned out to be keen hobby enthusiasts.
. This general idea, that 'keen hobby enthusiasts make the best technicians
~n~ engineers' is one that I've often seen expressed by overseas magazine
¢ditors as well - so it must have at least a fair degree of validity. Yet lately,
J've also seen and heard worrying comments like "Where have all the enthusiasts gone?" and "No-one seems interested in building things anymore ... "
• The other day I had the opportunity to talk to a Senior Lecturer in
Electronics at one of the local universities, and I asked him what proportion of
his students would also be hobbyists who had built up some projects,
or at least a few kits. His estimate was "Only about two or three
percent", and we both agreed that this didn't augur well for the future of
Australia's electronics industry.
, One can speculate at length about the reasons for this decline in hobby enthusiasm among young people. It seems likely that the growth of low cost
rsonal computers has played a part, seducing away at least some potential
ectronics enthusiasts with the promise of exciting games, multimedia advenure and the glamour of programming. Perhaps TV broadcasting has con~ibuted as well, by providing so much 'pre-digested' entertainment. But
}vhatever the reason, I do believe it's important that the trend be reversed if at
~ll possible.
i J:lere at EA we're certainly making every effort to boost our output of inter¢stmg and affordable electronic project designs, in an effort to attract more
)'oung people back into experimenting with electronics. We've just added to
~ur in-house staff a new project designer, Graham Cattley, to strengthen our
apabilities in this respect. And I'm happy to note that like the rest of us,
raham is very much a long-time enthusiast who loves playing with electronic
rrcuits and devices.
~
You'll be seeing Graham's designs in the magazine shortly, along with as
any other projects as we can fit in. So how about warming up that soldering
~ron, an~ tac_kling a constru~tion project soon. Building up circuits and getting
~hem gomg i~ the best possible way to learn about electronics - that's WHY
~obby enthusiasts make the best engineers and technicians!
e
r
Jim Rowe
ELECTRONICS Australia, February 1995
5
What's New in
VIDEO and AUDIO
Three disc CD
player from NAD
After careful market research, NAD
apparently found that most people do
not need to, nor even want to, play
more than two or three CDs after one
another, as the total playing time of
three CDs can be as much as three
hours and 45 minutes.
With this in mind, and by adhering to
their philosophy of 'no bells and
whistJes ', NAD engineers developed
the NAD 513. By employing the
carousel principle and limiting the
number of discs it can hold to three, the
mechanism could be built much simpler
without sacrificing either performance,
reliability or useful features. The end
result is a fully fledged CD changer
with the performance and price of a
single disc CD player.
Like other NAD CD players, the 513
achieves transparent and precisely
linear digital to analog decoding by
employing a single-bit MASH circuit,
while balanced filtering removes
ultra-sonic by-products of the decoding process to ensure no intermodulation distortion without affecting the
audio performance.
Despite its simplicity, the NAD 513
offers all the facilities normally associated with carousel CD changers two discs may be changed while the
third is playing; the remote control
makes changing discs and selecting
tracks easy without having to touch the
front panel; the programming facility
for 32 tracks over three discs makes
track selection a breeze; and with the
Random function engaged, all tracks
from all three discs will be played
without repetition.
The handy Edit function even helps
to choose tracks to fit onto a side of a
cassette without wasting tape or ending
a track abruptly.
Dual returns to Australia
Dual, the highly respected German
turntable manufacturer, has returned to
the Australian market. The company
that among many magnificent turntables, gave us the legendary CS-505,
now presents a complete range of audio
Technics mini hifi
The new Technics SC-CA1060 mini hifi features sleek curves, clean lines and is claimed to deliver superb sound output. It is a full separate component system, consisting of an
amplifier with phono input, a single CD player, double cassette deck and separate tuner.
The amplifier has 'New Class A' circuitry and large VU
power meters which give a more accurate readout of signal
levels. It features Virtual Battery Operation (VBO), which is
a feature normally associated with top end amplifiers. VBO
cuts off 'noise' from the main power supply to deliver richer,
cleaner sound.
The single CD player has MASH and digital servo for improved sound reproduction, plus 24 step random access
programming. The double cassette deck has dual autoreverse, power loading and Dolby B/C NR. It also has high
speed FF and REW and auto tape selector (Metal/CrOz/Normal). CCRT (computer controlled record tuning) function
tunes the deck to suit the brand/model of the cassette being
used for optimum performance.
The stereo synthesiser tuner has 39 station random access
presets and tuning job control. The three way speaker system
6
ELECTRONICS Australia, February 1995
features a 14cm woofer, 8cm mica composite cone midrange,
2.5cm soft dome tweeter and a 'noise silence' speaker
cabinet, delivering a power output of 40W x 2 (DIN).
The SC-CA1060 comes with a full remote control which
operates all the functions of the system. It carries an RRP
of $2749.
and video equipment. Dual has expanded into a full scale electronics supp lier with separate hi-fi components,
packaged mini and midi hi-fi systems,
VCR's, a complete range of televisions
and of course, a full line-up of 12 excellent turntables.
The fine reputation and strength of
the Dual brand name has helped the
company enormously to move into
these exciting new fields in Europe,
where it holds a considerable market
share. At the same time Australia is experiencing a 'Euro-Invasion' as a
variety of European cars compete head
to head with Japanese cars, while German televisions are enjoying unprecedented sales.
With this emerging 'Euro' trend it
was considered that now was the perfect time to relaunch the new look Dual
and re-establish the marque in
Australia. Distribution of Dual is via a
joint effort between Melbourne based
Scan Audio, a well established
loudspeaker import/distributor, and
Sydney based Indeco Sales, a newly established firm that also markets their
own German made Indeco 'La Linea'
hi-fi racks.
"We are very excited to be promoting electronics to compliment our
loudspeaker business. Dual is the perfect European prestige brand" said
Michael Henriksen, Managing Director
of Scan Audio.
New Classic Series
loudspeaker from Duntech
Australian audiophile loudspeaker
manufacturing company Duntech Audio
has released its new Viceroy (C2000)
loudspeaker.
According to Duntech Sales USA
National Sales Manager Brian Tucker,
the Viceroy is the product for consumers who have wanted the premium
performance of a Duntech but were unable to afford previous models. "For
less than $5000 our customers can
enjoy many of the benefits of the
legendary Duntech Classic Service such
as 'walk in' stage depth and width and
astonishing transparency."
The Viceroy is less than four feet
Large screen
projection system
The new Electrohome ShowStar LCD
Large Screen Projection System is
designed to deliver high brightness images with uncompromising reliability
for large venues including auditoriums,
conference rooms, trade show exhibits,
and lecture theatres.
ShowStar employs LCD projection
technology and incorporates Electrohome 's innovative light diffusion system to eliminate hot spots and provide
brilliant, clear text and images with
uniform brightness across the screen.
ShowStar retains sharpness of image
throughout a range of projection distances comparable to a conventional CRT
projector, while operational lenses are
available to facilitate long distance and
placement flexibility.
The system features a striped configuration of its LCD pixels to produce
the sharpest images possible. Each
pixel is in exact alignment with its adjoining partner to each side, as well as
top and bottom. The results are said to
be remarkably better, particularly on
fine text and vertical lines, than the
staggered pixel configuration employed
by competitive systems.
All functions are controlled by a convenient, back-lit remote keypad. Easy
to follow menus and 'slide-bar'
graphics allow adjustment of image
high and barely over one square foot in
plan. Its elegant lines reflect the styling
of its bigger brothers and sisters, with
styling elements to allow it to harmonise with homes in the 90's. It is
designed around completely new drive
units, and incorporates radical new
High Definition Aerogel drive units.
The Viceroy has three drive units in a
symmetrical array with two Bass/Mid
units above and below the tweeter. The
arrangement of drivers on the baffle,
with the tweeter coincident with the
acoustic centre of the Bass/Mids
provides for the simultaneous arrival of
sound at the listener distance of 12 feet.
In addition the point source character
of the microphones used to record
music are recreated by the vertical
layout of the drivers. The result of this
is claimed to be remarkable stereo imaging, depth, dimensionality and detail.
The useful low frequency limit of the
Viceroy is below 30Hz with in-room
extension (-3dB at 40Hz), which is
suitable for virtually any program matter, whether pure music or AN and
Home Theatre.
The sensitivity is 90dB SPL (2.83V
at eight ohms and lm). The impedance
is four ohms, with a well behaved frequency characteristic. The loudspeaker
is capable of huge dynamic range with
a continuous power rating of 150 watts
and continuous power rating of 500W
for I 0 microseconds.
The Duntech Viceroy is manufactured entirely by Duntech Audio at its
Australian facility according to strict
proprietary quality assurance standards.
It is hand assembled, finished in
authentic Australian Jarrah or Black
American Oak veneers. The
manufacturer's suggested retail price is
$4995/pair.
functions including brightness, tint,
contrast and colour saturation. ShowStar will display images from five to 25
feet (diagonal) in size, at a resolution of
640 x 480 or 550 TV lines.
Maximum usable brightness is 5000
peak (1000 ANSI) lumens, provided by
a 575W Metal Halide arc lamp with
1000 hours average life expectancy. A
change can be accomplished in under
five minutes.
Separate inputs are provided for composite video and S-Video sources, and
RGBHV computer sources. ShowStar is
compatible with video clock rates from
13 to 33MHz, horizontal scan frequencies from 14 to 37kHz and vertical scan
frequencies from 49 to 75Hz, interlaced
and non-interlaced. +
ELECTRONICS Australia, February 1995
7
Video & Audio: The Challis Report
ACCUSOUND'S 'PHASE
ZERO' LOUDSPEAKERS
After looking at the CSIRO's new A4 digital audio processing technology, this month Louis Challis has
been able to turn his critical attention to the world's first commercial loudspeaker system incorporating
this technology: the Phase Zero system, developed by Australian firm Accusound Loudspeakers.
Following last month's report on the
A4 VLSI Digital Audio Processor, I suspect
that many readers wil I already be
wondering both when, or where such equipment will be commercially available. Obviously, the very thought of being able to
integrate the A4 'black box' technology into
a system is exciting.
A system that can practically and effectively transform a relatively mundane
loudspeaker into a good, or better still, an
outstanding loudspeaker, is enough to make
most mouths water.
Having whetted your appetites, it is now
appropriate to further extend that interest by
reviewing what is currently the world's
first commercial loudspeaker system incorporating the A4 digital transform technology.
Al Henning is one of the Directors of
Accusound Loudspeakers at Kirrawee, NSW.
I have no doubt that he and his co-directors
believed they were enterprising when he
recognised the real potential of the A4 VLSI
digital audio processor.
As the story goes, on the day when Al discovered that the CSIRO had developed the
A4 chip, he immediately hopped into his
car, raced over to the CSIRO Division of
Radiophysics at Epping, and started
negotiatations for a licensing agreement for
his company.
Whilst I have no knowledge as to how
long he took to negotiate that agreement,
what I do know is that Al displayed considerable tenacity, and that he hung in there
untill that agreement was forthcoming. At
some later date, with a copy of the agreement in one hand and a developmental A4
system in the other, Mr Henning and his codirectors knew that they were standing at the
threshold of what they would prove to be a
new era in loudspeaker technology.
Whilst the CSIRO has provided Accusound with considerable technical and
moral support, there were numerous other
issues and obvious potential pitfalls facing a
manufacturer which is endeavouring to
adopt a new technology. In this particular
situation, the CSIRO A4 digital transform
technology posed many additional
problems, with the design configuration of
the speaker enclosure and the selection of
B
ELECTRONICS Australia, February 1995
the most appropriate drivers being one of
those critical issues.
As it happens, Al Henning received unstinting support from Barry Phillips of Magnavox Loudspeakers, who offered to develop
new drivers for this particular task.
We understand that it took them almost a
year of what they described as a very 'hard
slog', to perfect the Phase Zero speaker
enclosure. The development time was extended even further, as this was the first
production loudspeaker to incorporate the
A4 technology.
The loudspeaker design process was further convoluted by numerous technical and
visual issues. One of the more prosaic of
these was highlighted during Accusound's
market research. This indicated the
marketplace's preference for loudspeakers
with a 'small footprint'. In response to that
demand, the designers opted for a tall and
thin enclosure face panel. They selected a
face width of only 185mm and a height of
1170mm, believing that this would make the
frontal appearance of the Phase Zero
enclosure 'non-intimidating'.
For our review, we were provided with a
pre-production pair of loudspeakers. Each
enclosure is solidly constructed from high
density MDF board veneered on both sides,
with genuine Rosewood veneer on the four
sides as well as the top. The enclosure is internally stiffened with solid lateral braces,
and when tapped on any of its sides, or on
its top, provides a reassuring 'thud' instead
of a 'ring'.
With the elongated black cloth-covered
protective grille removed, your attention is
immediately riveted by the unusual array of
five loudspeakers. The driver at the top of
the array, in the enclosures that we received,
was a 25mm diameter titanium dome
A picture provided by the CSIRO's Division of Radiophysics showing one of their
A4 digital audio processor chips, and a development system incorporating It.
This photo shows the Accusound Phase Zero enclosures with their front grilles
removed, to show the array of drivers used - and also the porting.
tweeter manufactured in Taiwan. As I will
recount below, the production loudspeakers
will use a new European tweeter, which will
obviate problems previously identified by
the CSIRO in the pre-production prototypes.
Immediately below the tweeter are four
identical 125mm diameter Magnavox bassmidrange drivers. Whilst I initially thought
that the upper pair of drivers were the midrange and the lower pair were the woofers,
that presumption proved to be eroneous.
Whilst the manufacturer's literature claims
that the four drivers are configured as a
tapered array that differentially feeds the
higher frequency components to the highest
drivers, my investigations led me to a different conclusion.
In principle, the tapered array concept
sounds delightful. In practice, there are
numerous 'real world' problems to be
resolved, not the least of which in this
case is how well the tapered array will integrate with the A4 digital technology.
There was only one way to resolve that
issue. I examined the crossover in order to
determine how many components it actually
contains, and whether in fact those components fulfil all the relevant requirements of
a tapered array.
I opened up the enclosure by removing one of the central drivers,
which has the crossover immediately behind it on the rear face of the enclosure. The
crossover has two large air coiled inductors,
three resistors, and four capacitors. That
configuration cannot really provide a true
tapered array, as was suggested by the
manufacturer's literature.
At the rear of the cabinet there are two
sets of gold-plated 'universal' terminals,
which are incorporated in a neatly recessed
plastic enclosure. These terminals have been
designed to facilitate bi-amping of the Phase
Zero system. In practice, with the A4 digital
electronic unit incorporated as an integral
part of the system, there are some good
reasons for retaining the inter-links between
the upper and lower sets of terminals, and
retaining a conventional stereo two-channel
amplifier, rather than opting for a pair of
stereo amplifiers.
The enclosure incorporates a modest
amount of bonded polyester absorptive
lining, and a single port near the lower
edge of the covered front panel area - with
relatively sharp edges, which will increase the tendency to 'pant' at high
drive levels.
The base of the enclosure is splayed to
improve its stability, and on its underside incorporates four captive nuts at each of the
four corners. Each cabinet is provided with a
supplementary package of four sharp metal
spikes. These can be screwed into those
captive nuts, so that where required, the
enclosure can be 'spiked' to your polished
floor. As I discovered some years ago, my
emotional support person frowns on such
questionable habits, so I left the spikes in
their packet...
With each pair of Phase Zero speakers,
the manufacturer provides a matching black
ELECTRONICS Australia, February 1995
9
THE CHALLIS REPORT
The front panel of the Accusound A4X-1 digital processor unit, or 'black box', which supplies the high tech digital
equalisation used to flatten and linearise the performance of the speakers.
box which incorporates the essential
electronics for the A4X-1 digital transform
technology. The box is relatively innocuous
in its appearance.
On the front panel there are a series of
controls, only two of which really require
frequent use, and those are both on the left
hand side of the panel. The first is the
POWER switch, while the second is the selfilluminating DIGITAL TRANSFORM TECHNOLOGY switch. With the second switch
10
aECTRONICS Australia, February 1995
'OFF', the A4X-1 box provides a flat frequency response. With the switch 'ON', the
digital compensation is activated, and the
frequency and phase compensation individually determined for your pre-set
loudspeakers is then brought into play.
The A4X-1 electronics may be connected by either the normal line 'OUTPUT /IN PUT' sockets where they exist,
between the pre- amplifier output and the
line amplifier input of your main amplifier.
Alternatively, if such connections are not
available, the unit is connected by means of
the TAPE MONITOR sockets and switched
by means of the 'TAPE MONITOR' switch on
the front panel of the unit.
In the centre of the panel, a small
recessed LED is provided to indicate the
onset of clipping. In practice this LED should
never illuminate if the rear gain control has
been correctly set. But if that control has not
been correctly set, then the electronics will
At upper ten Is the transfer function magnitude plot for a compensated Phase Zero enclosure, while at lower ten Is the
matching transfer function phase plot. At upper right is the impulse response, while lower right shows the enclosures input
impedance plot. These curves were all measured using MLSSA.
go into the clipping mode on the highest
transient signals - or alternatively, the full
1OOdB-plus dynamic range of the A4X-1
digital technology will not be achieved.
On the right hand side of the A4X-1
module, there are two rotary controls. The
closest of these is the STEREO WIDTH knob.
This allows you to expand (or contract) the
'spread' of the stereo signal, which may
prove to be an advantage in some situations
- particularly if you happen to be an inveterate knob twiddler.
At the extreme right hand end of the panel
is a BASS COMPENSATION control. This allows you to select a conventional loudness
contour with the control turned towards the
clockwise extreme, or alternatively allows
you to select an artificially boosted response
(described as the 'JIVE DRIVE' position), by
turning it in the counter-clockwise direction.
The rear panel is relatively simple, with
two pairs of Line input/output coaxial sockets, and two pairs of Tape input/output sockets. A single rotary input level gain control is
provided on the right side of the rear panel.
The power is provided through a conventional IEC mains socket, at the extreme right
hand end of this panel.
The plan, or 'footprint' dimensions of the
ca bi net have been selected so that it can
comfortably sit immediately below the
majority of power amplifiers, with a power
rating in the range 20 - 200 watts per channel. The cabinet is solidly fabricated, so that
the weight of such equipment should not
result in significant distortion, or in premature damage as a result of SOkg deadweight
being applied on a continuous basis.
Objective testing
Following their receipt, I placed the 'B'
module of the pair of Phase Zero speaker
enclosures into my anechoic chamber.
Obviously, I was keen to discover what
the frequency response would look like
without the application of the much-vaunted
A4 technology.
I was not really surprised to find that the
frequency response was not flat. But on the
basis of other loudspeakers that I have
recently assessed, it· is doubtful whether I
would have guessed that the frequency
response would be nominally +5/-8dB over
the frequency range 45Hz to 20kHz. When I
measured the swept frequency response of
the 'B' module, with the A4 technology activated, the response was flatter than I would
have expected, and was effectively +/-1 .SdB
from 40Hz to 20kHz as you will observe,
with a SOdB potentiometer (SOdB pot) installed in the level recorder.
With a 1OdB potentiometer, the magnitude
of the perturbations are more clearly evident
- but in a practical sense, they confirm an
overall smoother response than might otherwise have been anticipated on the basis of
the technology used.
Yes, whilst I acknowledge that there
are obvious perturbations, of course all
things being equal, the magnitude of those
perturbations are generally below the
dynamic range of what most human ears
ELECTRONICS Australia, February 1995
11
THE CHALLIS REPORT
The compensated Phase Zero system's decay response spectra plot, showing a
particularly smooth and well behaved performance. Louis Challis described it as
'a textbook response' - the first he's ever seen.
would be able to detect in terms of their differential level.
By that, I mean that the human ear can
only really detect differential level changes
of the order of 2dB or more, unless you are
a skilled and/or an experienced musician.
Before removing the 'B' speaker from the
anechoic room, I carried out a series of
other tests which included a phase test (both
with and without the A4 frequency compensation applied), an impulse response, a
transfer function, an impedance curve, and
most telling of all, a decay response spectra
test. The phase response of the equalised
Phase Zero was particularly impressive, but
12
ELECTRONICS Australia, February 1995
not nearly as impressive as the decay
response spectra.
Now over the last 13 years I must have
plotted the decay response spectra of in excess of 100 loudspeakers. Some of the
loudspeakers cost as much as $20,000 a
pair, and would be classified as being
'amongst the best monitoring loudspeakers
that money can buy'. But the Phase Zero's
decay response spectra was the first that I
wou Id describe as being a 'textbook
response', with no significant signs of frequency, non-uniformity and virtually negligible signs of low level ringing in its decay
response spectra.
To say that I was impressed would be a
mild understatement. I quickly raced out to
the anechoic room, and with my assistant's
help, we auditioned the 'pink' noise
response of the loudspeaker - firstly with,
and subsequently without the A4
equalisation being activated. The results of
that subjective test immediately confirmed
how effective the A4 transform technology
really is.
With the A4 equalisation activated,
the 'pink' noise response of the speaker
on axis at 1.Sm or 2m was 'silky
smooth', and with minimal traces of
colouration at low frequency.
My next test was to evaluate the swept frequency response of the Phase Zero
loudspeakers at different distances, at different angles, and also with a 1OdB potentiometer in the level recorder. That test as
you will note, highlights the magnitude of
the minor acoustical perturbations in the
compensated frequency response.
The last test that I carried out in the
anechoic chamber was to swap the 'A'
enclosure for the 'B' enclosure, to assess
how accurate the frequency compensation
will be when applied to the 'other unit' of a
nominally matching pair.
As
I
discovered,
the
frequency
response of unit '/\ when measured at the
same position as unit 'B' provides a
reasonably good, but not perfect compensation of that frequency response.
The differences between the two spectra
(' N versus 'B'), are highest at high frequencies, and that confirms the need for the
manufacturer to use matched pairs of
tweeters if optimum compensation is to be
achieved in the matching speakers.
Listening tests
When I transported the two Phase Zero
speakers home, I had no difficulty fitting the
two cartons on the back seat of my car, and
I soon had them installed in my living room.
There was absolutely no problem to couple
the outputs of my pre-amplifier stage to the
inputs of the A4X-1 digital transform 'back
box' unit, and similarly its outputs to the inputs of my separate power amplifier.
With the very willing support of my
listening panel, we proceeded with an
evaluation of the subjective performance of
the compensated Phase Zero speakers in a
direct 'A-B' comparison with my B&W
801 M monitor speakers.
The first disc we selected for our evaluation was track 18 of the Sheffield Coustic
test disc, which provides three minutes of
'pink' noise. The subjeotive impressions of
the anechoic room were replicated in my
listening room, and apart from the low frequency end which sounded quite different to
what I had heard in my anechoic chamber,
the rest of the response was still very smooth
(see attached graph).
We progressed to assessing the response
of the loudspeakers on what I have always
found to be the most critical test of all - the
human voice. Dame Joan Sutherland
provided her staple test, and was supported
Brubeck's first solo recording in nearly 40
years, and in my opinion, it was well worth
waiting for.
With this more contemporary style of
music I had great difficulty discerning differences between the monitor speakers and
the Phase Zeros, and I guess that's the way it
should be.
Summary
The measured polar response characteristics of a compensated Phase Zero
enclosure, at 1kHz, 3kHz, 6.3kHz and 10kHz. Again, they're commendably
smooth.
by Bolshoi star Zurab Sotkilava in a brand
new disc in which he sings 'Famous Russian
Tenor Arias & Folksongs' (Sony Classical
SMK 57653).
At high listening levels (peaks of 95105dB), I was aware of a significant change
in tonality and spectral balance between the
Phase Zeroes and my monitor speakers. Flat
frequency response is one parameter, distortion and particularly high frequency distortion is - it would appear - a somewhat
different matter.
Whilst performing well at low to modest
listening levels, the Phase Zero loudspeakers
may not necessarily respond like a perfect
loudspeaker at high listening levels. At those
levels, the dynamic transfer characteristics of
the drivers (and particularly the tweeter) assume a very critical significance, which cannot be understated.
I progressed to a more contemporary disc,
with the famous Dave Brubeck playing a
new solo recording 'Just You, Just Me' (Telarc
Jazz CD-83363). This appears to be Dave
I kept the Phase Zero loudspeakers at
home for nearly two weeks, and listened to
a wide range of classical, operatic, orchestral
and pop music. Their performance was by
and large extremely good, and in many
respects, better than could be expected from
a speaker system where the manufacturer
has already advised that the tweeter will be
changed to a pair of individually matched
superior drivers when the full production run
is released, early in 1995.
The Phase Zero loudspeakers and their
A4X-1 technology will possibly be viewed as
a gimmick by many readers. Let me immediately dispel that view from the outset. The
A4 technology is here to stay, and it offers
dynamic performance which is a delight to
behold, and a delight to audition.
I am sufficiently impressed with the A4
technology to state positively that this
development is the most outstanding that I
have seen anywhere in the world in the last
10 years. I believe that as the development
of the A4 technology expands, it will change
our perception of what we want from a
loudspeaker. More importantly, it appears to
offer a practical means of replicating the
dynamic characteristics of the original sound
field in the home listening environment.
The Phase Zero enclosures measure 1170
x 185 x 300mm (H x W x D), and each
weigh 23kg. The quoted price for the Phase
Zero system is $4000, including the all-important A4X-1 'Black Box'.
For further information contact Accusound
Loudspeakers, 2/7 Marshall Road, Kirrawee
2232; phone (02) 545 3905. +
PINBALL MACHIN~=
- SCORE/ALPHA NUMERIC DISPLAYS
- KEYBOARDS - GRAPHICS DISPLAYS
- ELECTRONIC COMPONENTS
- MICRO SWITCHES
[D) ® ~ ~© (LJ) [fi} ~
1 Wickham Terrace
Cnr Ann & Wharf Streets
Brisbane Old 4000
Phone (07) 839 6155
Fax (07) 832 5278
• ICOM COMMUNICATIONS
• HEWLffi PACKARD
CALCULATORS
• SWANN SWITCHES
·ARISTA
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ELECTRONICS Australia, February 1995
13
Moffat's
Madhouse. ••
by TOM MOFFAT
Reflections on the 'Quackintosh'
Ah! It's a bright summer morning
and the birds are singing. A flight of
finches just fluttered past, and the currawongs are out there begging for their
daily hit of dog food. For months,
every day has been heralded by the
family of kookaburras that's made its
home in one of our trees. They start the
morning winding up their screeching
apparatus, first with low giggles and
then progressing to maniacal shrieks.
Lately they've even been giving their
babies screeching lessons at 5:30am.
Birds are no novelty to us; we even
had some peacocks for a while. So it
came as no real surprise when I was
working away with a Macintosh computer one day, and something went
'quack'. It was obviously just one of
the ducks. But hey, wait a minute we don't have any ducks! What
went 'quack' then? Must have been
my imagination.
Some time later - 'quack' again.
Just one quack, that's all. And when it
happened a third time I finally deduced
that the quacks were coming from the
Macintosh. Again, no big surprise here,
because the Macintosh has quite a
vocabulary of interesting noises. It
sometimes chimes, like an airplane
does before it says "This is your captain speaking ... " And if it really wants
to draw your attention, it emits a
raucous 'boingggg .... '
But why does the Mac quack? I mentioned this strange behaviour to an acquaintance, who spends a lot of time at
the university where there are Macintoshes by the room-full. "Oh, don't
worry about that", he said, "all Macs
quack". But why do they do it, I
asked? "I've no idea," said the uni-person, "it's just something that Macintoshes do."
This illustrates a principle I shall call
'having blind, unquestioning faith in
one's computer'. If the computer does
something it must have its reasons.
Inquiring into the computer's actions is tantamount to asking if life
really has meaning.
14
ELECTRONICS Australia, February 1995
Just for the record, when my Mac
quacks, it is marking the passage of an
hour on its internal clock. It's like Big
Ben with webbed feet. Now imagine
the above-mentioned room full of
Macintoshes at the university, and
when each hour passes there is a chorus
of 'quack-quack-quack'. All the
academics and students therein pause
briefly from their tasks and note that
once again, all the Macs are quacking
at each other. But apparently nobody
asks why. It's just 'something that
Macs do'.
I am not really a Mac person, and
I'm somewhat ambivalent about working with a Macintosh. After having the
thing around for several months I'm
still running with my L-plates, and it
seems that the Mac resists my every attempt to get it to do anything. It
definitely has a mind of its own, if
computers have minds.
But one spinoff from its 'userfriendliness' is its rather wry sense of
humour, which I find quite delightful.
The quack is just great; it's almost as if
the computer is taking the Mickey out
of itself. Same goes for the boings.
I suppose if you really worked at it,
you could re-program the thing so it
only used its boring old this-is-thecaptain-speaking chime for all announcements, making it more suitable
for a stodgy business environment. Or
you could gq the other way - I
understand there is one Macintosh in
the university library that greets
every action with an announcement
from
its
speech
synthesiser:
"I MAY BE A COMPUTER BUT I'M
NOT STUPID!"
. Well, I'm a person and I don't think
I'm stupid either, but sometimes I feel
the Macintosh does think I'm stupid.
What bugs me is that the Mac has its
own ways of doing things which are totally beyond my control. For instance, I
wanted to copy a file. Since the Mac
has no command line, I couldn't just
type 'copy... ' as you do with MS-DOS.
So I decided to consult the instruc-
tions, the 'Macintosh Reference
Manual'. I checked the index under C
for Copy, which eventually directed me
to an instruction called 'duplicate'.
'Copy' only applies to the process of
'duplicating' stuff from one disk to
another by CLICKING on it with your
mouse and then DRAGGING it from
where it is to where you want it to be.
Should you DRAG something from
place to place on the same disk, you
end up 'MOVING' it; that is, copying it
and then deleting the original.
Now, if you erase your mind and
start from scratch, this dragging business does seem somewhat logical. And
it didn't take stupid old me too long to
figure out that if you want to DELETE
a file, you DRAG it to the little image
of a garbage can. So it seems to me
that to be a happy Mac user, it is best
to start with a blank mind as far as
computers go.
A similar situation existed at the
place where I did pilot training, a very
large commercial flight school with
branches for both fixed-wing aircraft
and helicopters. The chief helicopter instructor told me that his most difficult
students were the ones who were already fixed-wing pilots, because you .
had to un-teach them all their old flying
habits before they could begin to handle a helicopter. The problem appears
similar with MS-DOS and (horrors!)
CP/M hackers like me: we've got to
un-learn all the old habits before we
can successfully take on the new.
Not long after I got the Listening
Post II and Wesat kits going, I started
hearing requests along the lines of
'when are you going to do versions for
the Amiga?'. So I bit the bullet, bought
an Amiga computer, bought a pile of
expensive books, and got into it. And
the first thing I discovered was that I
was presented with the dreaded Graphic
User Interface when I turned it on.
the second thing I discovered was
that the Amiga designers had made allowances for troglodytes like me. It
was possible, with minimum effort, to
arrange the Amiga to work from a
traditional command-line interface instead of the new-fangled GUI.
Once I figured out how to do that, it
was goodbye GUI forever, at least on
the Amiga. Saved from the grip of
progress that time!
But as for the Macintosh, well it doesn't look like there is any
way to revert to a command-line option. So I was just going to have to get
with the GUI.
As this is being written (on my trusty
MSDOS-based laptop), I've had about
two weeks of intensive Mac experience. I've been busy working up a
new version of the Pocket Packet radio
modem system, so that it (1) runs on the Macintosh, and
(2) works in the latest TCP/IP mode.
Because of the Mysteries of the Mac,
I thought it prudent to get similar
TCP/IP software running on the IBMPC and then transfer the techniques
learned over to the Mac. So now we've
got a TCP/IP version of Pocket Packet
working on the PC as well.
Most of the work involved editing
various configuration files to make the
software and the Pocket Packet modem
talk to each other. And at one stage I
had PC laptop and a Macintosh Classic
II sitting right next to each other on the
table, each editing its own version of
the configuration file in its own individual way. So it was an ideal opportunity for an A-B comparison between
the two systems.
An example: let's move a couple of
lines of text from one place in the file
to another. On the PC (at least my laptop, running the VDE text editor), you
use the cursor keys to place the cursor
at the start of the block you want to
move, and then press the F7 key. Then
you move to the end of the block and
press F8. The block changes colour, so
you can confirm it's what you want to
move. Then you move the cursor to
where you want the block to be, and
press F9. The block is moved; all done.
To do the same thing on the Mac,
you use the mouse to move the
cursor to the start of the'block. Then
you hold down the mouse button, and
sort of wipe the cursor over the text
you want until the correct block has
changed colour, when you can release
the mouse button.
Now you must open a menu at the
top of the screen, and click on 'cut'.
The screen jumps down to where the
block was, and you notice the block's
not there any more. Next you use the
mouse to move the cursor to where you
want the block to be. Now you open
the menu again and click on 'paste'.
The block is moved to the new position; all done.
I have gone through these motions
many, many times, first on one computer and then on the other - left computer, right computer, left computer,
right computer. I think I've given both
of them a pretty fair trial. But I am
sorry to announce that I still find the
PC way of doing the job quicker,
easier, and more foolproof. Note that
we're talking MS-DOS here, not Windows, which works pretty much the
same as the Mac.
Still, it is patently obvious that I am
going to have to learn to love the GUI
way of doing things eventually. Present
IBM-PC's, like the Amiga, always give
you the option of abandoning the whole
GUI thing and going back to work in
DOS. But two new developments the new version of Windows known as
'Chicago', and an interesting operating
system called OS-2 - do away completely with the need for MS-DOS in
the computer. And with goodbye DOS,
it's goodbye command-line and hello
GUI forever.
whacko! Along with 'current' and
'currency', there it was: 'currawong'.
As for kookaburra, a search for 'kook*'
produced, as well as the bird, 'kook' or
'kooky', a strange or eccentric person.
Hey, maybe that's how that silly bird
got its name!
I've always thought a personal online dictionary would be a handy thing
to have, and I've been hanging on for
several months waiting for the release
of this one. It's particularly useful for
me because of its Australian emphasis.
The spell-checker I always use when
writing this stuff is of American origin,
and although I've tried to teach it more
civilised spellings from time to time,
the occasional clanger still creeps
through. And when you hit it with
something like kookaburra the thing
goes right off its brain, suggesting such
charming alternatives as 'knockwurst'.
By now the Megafloppy Macquarie
should be available in just about any
newsagent in the land, and in keeping
with the tradition of that little book I
used previously, the disk is bright yellow. If you ever do any writing, even as
a student doing school reports, the
electronic dictionary is certainly worth
Electric dictionary
a look.•>
Now let's change the subject some- . - - - - - - - - - - - - - - what. In the first paragraph of this
column you'll notice two words - currawong and kookaburra - which I am
pretty sure are spelled correctly. This is
no mean feat for a writer such as me,
of American manufacture, educated in a
land where the above-mentioned birdies
only exist on travel posters, if at all.
How did I get so smart and talented,
ETCH TANKS
you say? With my trusty electric Mac• Bubble Etch • Clrculatlng
quarie Dictionary, that's how! I used to
LIGHT BOXES
carry a little yellow book around in my
'portable office' case, a mini-Macquacy
e Portuvee 4 e Portuvee fS
Dictionary. But now that dictionary
•Dual Level
lives within my laptop computer on the
TRIMMER
hard disk.
e Ideal
Some time ago you may remember I
came across some other books on these
PCB DRILL
new 'Megafloppy' computer disks; the
• Toyo HISpeed
Australian Constitution, the full text of
the High Court's Mabo decision, and
MATERIALS
the Holy Bible. All are useful reference
•PC Board: Riston, Dynachem
works on occasion, but the one to get
• 3M Label/Panel Stock
used every day has turned out to be the
Dynamark: Metal, Plastic
•
new Macquarie Dictionary on a
AUSTRALIA'S N0.1 STOCKIST
Megafloppy, transferred across to my
hard drive.
I must admit I didn't have a clue how
to spell either of those bird names, but
I guessed that one had to start with
'curr.. .'. The electric dictionary lets you
40 Wallis Ave, East Ivanhoe .3079.
do wild-card searches, using the '*'
Phone
(03) 497 3422, Fax (03) 499 2381
symbol to match anything. So I told it
the word I wanted was 'curr*', and
KALEX
The UV People
*
ELECTRONICS Australia, February 1995
*
15
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APPLE'S QUICKTAKE
DIGITAL CAMEU
This affordable, pocket sized digital camera can be hooked up to a Windows-based PC as well as
an Apple Macintosh. With direct electronic output of its captured images, it will probably answer the
picture-making needs of many.
by BARRIE SMITH
If you've lived happily
with the operational style of a
Nikon or Canon SLR, you
may have difficulty coming to
grips with the Apple QuickTake 100. But, if you've
craved for a 'transparent'
method of getting a picture of
any sort expeditiously into
your Mac or PC, then QuickTake is your answer.
Compared to a conventional
still camera, QuickTake has
some pluses and some minuses.
On the plus side, there's no
film to load, no wait for
processing and - if your images are to end up inside a
computer - no scanning. On
the minus side the camera has a maximum capacity of only eight shots (at
top resolution), no focus or exposure
controls, and possesses the most
rudimentary flash system. The shutter
speed, in low light, could also induce
camera shake in less-practised hands.
An attractively styled charcoal-toned
case houses the Kodak-designed CCD
(charge-coupled device) sensor, optical
system and other circuitry. Externally
there is a sliding lens cover and flash
unit on the front, while at the rear is an
LCD panel displaying operational
modes such as flash on all the time,
auto or flash off, resolution level, self
timer and exposed frame count.
At the side is another panel which
conceals the serial port and 4.5V DC
input. On top is the shutter button and here, I found trouble within two
frames of shooting my first batch of
pies. The firing button is just too easy
to trigger accidentally, and that's exactly how I captured my first digital 'walking feet' image ...
The camera is powered by three AA
batteries (NiCad or conventional accepted). The images are stored on an internal Flash EPROM, and will remain
in memory for a year even if batteries
are removed; should the lens cover
16
ELECTRONICS Australia, February 1995
(which doubles as the power switch) be
left open, the camera will shut down
after five minutes.
The picture format is 4:3 ratio. You
can expose up to 32 pies at the 'standard' resolution of 320 x 240 pixels, or
eight at the 640 x 480 pixels high
resolution. Both are in 24-bit colour,
and resolution levels can be mixed.
Apple's QuickTake 100
Basic Information
1MB Flash EPROM stores up to J2
standard-res or eight high-res image
files or mix of both. Storage time up to
one year.
Shutter speeds 1/30 to 1/175 sec. Aperture f/2.8 to f/16.
Weight: 500g.
Film equivalent: IS085.
Interface: Mac 68020 equipped computers, 4MB RAM + 8MB of virtual
memory or 8MB RAM, HD floppy
drive, System 7.0.1 or later, hard drive
with 10MB or more.
Windows PC compatibility.
Accessories: Travel case, battery
booster pack.
Pluses: Simple computer interface.
Minuses: Very basic auto exposure system.
RRP: Camera $995. PhotoF/ash $245,
bundled with Camera.
Once dumped into a Mac or
PC, the file sizes come in at
around 30KB or 120KB respectively. So a whole run of 32
standard-res or eight hi-res pies
will total just under lMB.
Because the lens is fixed
focus, you are restricted to a
minimum shooting distance of
1.9 metres (4ft). This I didn't
find a great worry, as the 8mm
focal length lens is equivalent
to a 50mm on a 35mm SLR and
pleasing head and shoulder
shots are still possible.
If you 're a fiddler, I dare
say you could try slapping a
supplementary lens on the front
and move in closer. The viewfinder is a simple, direct optical
design, but more than adequate for this
style of camera.
Matching software
The interface software is supplied on
two HD floppies: this includes the
QuickTake application, camera system
extensions, Color Sync control panel
and a range of profiles for a number of
colour monitors.
The application loads the camera images onto your hard drive, a chore
which takes little more than a minute.
Once you've established a group of
thumbnails on the desktop, you can
select an individual image, rotate in 90°
increments, cut, copy, paste, crop, rescale and zoom in on it. Export file formats include TIFF, BMP and PCS
(Windows), JPEG and native QuickTake. Additionally, the images can be
transformed to single- bit, 8-bit and 16bit renditions. Should you save a
high-res file in uncompressed PICT
format, the final file size will be close
to 900KB.
In practice
I found it fascinating to hook up the
camera to a Mac and control it from the
desktop. Like to take a shot? All func-
WAVETEK
Stealth SAM
Model 4040 Signal Analysis Meter
More Than Just A Signal
Analysis Meter
The Stealth SAM presents a broad scope of practical test
capabilities - so many that it is similar to a hand-held
broadband communication service monitor. Essential Cable
TV system preventive maintenance tests are performed with
accuracy and ease. Signal levels, hum and C/N can be quickly
tested without interrupting subscribers' reception. And all with
unprecedented accuracy, speed and minimal training.
One of the pictures taken by Barrie
Smith using the Apple QuickTake 100.
tions can be controlled through the
QuickTake application; fire the shutter
and the image comes up on screen in
around 10 seconds.
What's the quality like? Opening a
high-res file on my 14" Trinitron
screen's 72dpi display gave me a picture a touch unsharp; mind you, that's a
display of around 280 x 210mm.
The standard-res file quality was, I
have to confess, a little ragged - so my
tip is to go for high-res every time.
When I output the pies to a
360dpi inkjet colour printer the image
size shrinks to 110 x 85mm and apparent sharpness rose at the same
time, resulting in a truly useful picture
(see example).
The exposure system is elementary
in the extreme and too easily fooled
by bright skies - and any overall lighting arriving on the subject from any
direction other than 'over the right
shoulder'. I achieved superb results in
soft lit conditions.
Apple recommends that the flash system should only be relied upon for subjects within a 1.9 - 4.5m (4-9ft) range.
To this I would add that you should
look for interiors with light ceilings and
walls to augment this.
Colour quality I found to be surprisingly good - well saturated, and
provided your exposure was within ball
park, a little judicial fiddling with a
package like PhotoShop or PhotoFlash
could reward you with excellent results.
The camera is available as a bundle
with PhotoFlash software, and this is an
option I recommend.
I suspect Apple's QuickTake digital
camera has a lot of customers out there
waiting for it. •:•
• 5 MHz-I GHz Frequency Range
•Easy to Read Graphic Signal Measurement; High
Resolution LCD (320 x 240 dot matrix)
•Hum and Carrier-to"Noise Tests
on Modulated Carriers
•Comprehensive Tilt/Scan Analysis Modes
• Sweepless Sweep Frequency Response Measurement
•Spectrum Analyser Display
• Signal Level Measurement
•Single Channel
•Tilt (Up to 9 Channels)
•Scan (All Channels)
• C/N on Active Channels
•Hum on Active Channels
•Weight 3.5 pounds (1.6 kg)
•Durable and Water-Resistant
• Automated Testing
eLogging
0)
SCIENTIFIC DEVICES AUSTRALIA
PTYLTD
ci
Melbourne (03) 579 3622
Fax (03) 579 0971
Sydney (02) 344 5200
Fax (02) 349 2602
Adelaide (08) 281 3788
Fax (08) 281 4194
u.
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ELECTRONICS Australia, February 1995
17
-------------------
·-·-----------
THE WORLD'S
BIGGEST TELESCOPE
Around the turn of the century, the twin 1Om telescopes of Hawaii's Keck Observatory will no longer
be the world's largest optical telescope. That status will pass to the ESO's Very Large Telescope, a
set of four 8.2m instruments planned for a mountaintop in Chile.
by GEOFF McNAMARA
It's a well-known fact that the bigger
the telescope, the more you can see. But
astronomers reached a crisis point a few
years ago, when they found that there
was a limit to how big you could make a
telescope and still get it to point at the
sky without falling over (or at least, distorting its framework).
The telescopes with the largest single
mirrors ever made will be a pair of giant
10-metre telescopes under construction
at the top of an extinct volcano in
Hawaii. But the record for biggest telescope will be overturned almost as soon
as its made. By the turn of the century,
the largest telescope in the world will
have an equivalent aperture of 16
metres. The telescope is imaginatively
called the 'Very Large Telescope' (VLT).
The VLT is actually four 8.2-metre
telescopes. By combining the images
produced by all four telescopes, the VLT
will perform as if it were a much larger
telescope - but without the structural
problems associated with such a large
telescope. The quartet is being built by
the European Southern Observatory
(ESO), a consortium of astronomers
from eight European countries.
The VLT is being built on top of
Cerro Paranal, a 2640-metre high mountain in the middle of a desert in Chile.
The skies there are among the darkest,
steadiest and driest (important for infrared astronomy) in the world. The
ESO is now ready to install the first
telescope's enclosure.
Radio astronomers have been able to
combine the signals of widely-spaced
receivers for many years, and this is in
fact the basis of the well-known
Australia Telescope whose individual
components are separated by up to
hundreds of kilometres.
Like the Australia Telescope, each of
the four telescopes that make up the
VLT can be operated independently or
in unison. When working together, their
combined light-gathering power will be
the equivalent of a 16-metre telescope.
18
ELECTRONICS Australia, February 1995
When used as an interferometer, the
telescopes will have the resolving power
of a telescope with an aperture the same
as the distance between the two farthest
telescopes - about 100 metres. Alternatively, the telescopes can be used on the
same object but with different instruments, or on four different objects.
The appearance of the completed observatory will be a far cry from the
traditional dome-shaped buildings that
were used to house telescopes in the
past. Designers have since discovered
that the dome is one of the worst
shaped-buildings that you can use for a
telescope, simply because the air cur-
rents it creates around the telescope distorts the images. The new method is to
use box-shaped enclosures that move
with the telescope as it looks around the
sky. To further improve the steadiness of
the surrounding air, astronomers will
work in laboratories and move between
the telescopes underground. Nothing
will protrude above ground except the
giant telescopes themselves.
Telescope One of the VLT is due for
completion around late 1997. The
remaining telescopes will be completed
over the following few years. The
total cost of the project is estimated at $430 million. •:•
HIGH TECH IN A
MODERN CINEMA
Electronics has always had strong links with the motion picture industry, and from time to time in the
past we have published articles describing the development of cinema technology. Here's an update, showing the way modern 'multiplex' movie theatres have taken advantage of recent developments in electronics and computers. The author is an experienced projectionist, currently working in
Shepparton, Victoria.
by REG LEAHY
Over the years that I have been reading Electronics Australia, I have enjoyed
the many articles on the movie industry.
Following the article by Mr Rod Maclean, in the March 1993 issue, I decided
to put finger to keyboard and take
readers from the era when I myself
started to get involved in projecting
moving images onto a screen, up to
today's technology as used in modern
'multiplex' cinemas.
My involvement in the movie industry
started in 1976 at the Regal Cinema in
Benalla, a city in North Eastern Victoria.
Here I met and made friends with the
proprietor, a Mr 'Hoot' Gibson (who was
given the nickname of Hoot after one of
the silent screen cowboys), who was
amongst the first of the travelling 'picture show' men in Victoria and South
Australia. Hoot showed me the techniques used in how pictures are screened.
I was 'hooked', and started to go to
the th~atre as many times as I could to
learn the skills of being a projectionist. I
enrolled at Royal Melbourne Institute of
Technology and completed a two year
correspondence course. In 1980 I passed
the Victorian Public Health examination
and obtained my Cinematograph
Operators Licence. During my practical
training at the Regal Cinema, I performed the duties of assistant projectionist - cleaning the projectors,
threading the film in the projectors,
cleaning the mirrors, replacing and adjusting the carbons in the lamphouses,
and rewinding the film as each spool
finished screening. By the time I had
completed these tasks, the next spool
'changeover' was ready, and the whole
cycle started again.
After a few months of practice, I was
achieving having everything ready for
the next changeover in a shorter time
than before. This allowed me time to
relax and enjoy some of the film that
was screening.
20
ELECTRONICS Australia, February 1995
Our lead picture gives a view of the film path from platter to projector, with the
Manager making adjustments to the feed out rollers.
Flg.1: A 4kW Xenon bulb, In the centre of the parabolic mirror with the Igniter
circuitry at the back, as used at the Twlllght Drive-In Theatre, Shepparton, Vic.
On one occasion Hoot said he had to
go downstairs to the ticket office and
that he would be back in a moment. The
film in the running projector started to
reach the end of the spool and a changeover was rapidly approaching, with
no Hoot Gibson to be seen. I took
the bit between my teeth and managed
my first solo changeover. It was spot on.
Afterwards Hoot came back into the
projection room and said that he had
been sitting in the theatre, waiting to see
how I would manage a changeover
without supervision...
As I was preparing my notes for this
article, a pamphlet arrived on my desk
where I am presently employed, advertising a new digital sound system for
theatres. When I had finished reading .the article, I felt like Marty
McFly and Doc Brown and had gone
Back To The Future.
(At this point I would suggest that if
you haven't already read the article by
Rod Maclean in the March 1993 article,
you might read it. He describes one of
the first sound systems developed for
commercial use. Basically it consisted of
a turntable driven by the projector motor,
with a 16" (40cm) disc revolving at
33.3rpm. The projectionist would cue up
the record to synchronise with the start
of the film, prior to the commencement
of that spool.)
The new digital system uses a time
code placed between the existing stereo
soundtrack and the image area. As the
film moves through the projector, the
timecode is read by a special optical
reader, placed near the existing sound-
head, where it is then decoded to control
the CD-ROM disc in a modified CD
player. The discs are synchronised to
each individual frame of the film, by the
time code.
For a theatre that has only stereo
playback, a single disc is used and con-
tains four hours of soundtrack. A theatre
with a full sound system (left, centre,
right, left and right back channels, and a
subwoofer) requires a two disc player
which gives three hours and 20 minutes
of playing time.
If the wrong discs are sent with the
film, the time code signal will not let the
disc play and will default to the original
optical soundtrack. By using this method
with the timecode and conventional
stereo soundtrack on the one film, the
film distributors do not need two different prints of the same film - i.e., one
with a digital soundtrack and the other
with an optical soundtrack.
This, as you can see, is a different approach to the system as developed by
Kodak, where the digital information is
placed on the film, replacing the existing
soundtrack. (See Electronics Australia
November 1990, page 20.)
Now back to the past, to the Regal
Cinema where I started my interest in
being a projectionist. Its plant consisted
of two Kalee projectors with Gaumont
arc lamphouses, a valve mono amplifier,
manual resistance dimmers for the lighting and an AC Transarc stereo slide
projector. This was standard fare for the
theatres of this vintage.
The owner of the Regal was very
progressive in his thinking and decided
he was going to upgrade his theatre by
the installation of a Dolby Stereo Surround Sound decoder and a four channel
amplifier (see Electronics Australia April
1990 page 34). He also decided to install
solid state light dimmers and to replace
the old carbon arcs with Xenons.
Xenon arcs
A view of two Xenons out of their
protective covers, showing a 4000W
bulb and a 1500W bulb.
The Xenon short arc was developed
by the Zeiss Icon company of Germany
in 1954 (Fig.1 ). The name Xenon is
derived from the Greek word 'Xenos',
which means stranger, and is a reference
to the rarity of the gas - in which only
one cubic metre is found to every fifteen
million cubic metres of air.
The Xenon arc is a gaseous discharge
lamp, with high quality tungsten
electrodes set in a fixed gap relationship
between anode and cathode, and is
sealed in a blown quartz bulb in an atmosphere of pressurised Xenon gas. The
initiation of the arc between the fixed
electrodes is achieved by a pulse of high
voltage radio frequency power which
jumps the gap and ionises the gas, thereby providing a path for the main DC
supply to maintain the arc.. Once established, the arc is stable after a very short
warm up time.
The colour characteristic of the Xenon
lamp is as close to daylight as can be
ELECTRONICS Australia, February 1995
21
Hi-tech in Modern Cinemas
achieved. The bulbs are rated from
450 watts to 6500 watts and are guaranteed for a minimum of 1000 hours. At
the theatre where I am currently
employed, there is one Xenon bulb th.at
has achieved over 6000 hours and still
going strong.
At the Regal Cinema the existing
carbon arcs were replaced by Xenons
and the photoelectric cell was replaced
with twin silicon solar cells on a
modified bracket to allow adjustments to
be made - so that the stereo cells reads
each track correctly, without any
crosstalk. The Dolby decoder, four channel amps and speakers were finally connected and tested. This produced a
dramatic improvement to the shows, for
the enjoyment of the cinema patrons. All
this was attached to a pair of Kalee
projectors which were second hand
when the theatre was built in 1956!
At the same time that the Regal
Cinema was being updated, the ownership of the local drive-in theatre had
changed, and the new owners also replaced the old carbon arcs with Xenons,
replaced one of the old Cumming &
Wilson projectors with a new Simplex
projector (Fig.2), leaving the other Cumming & Wilson projector as a spare.
They also installed Cine-Fi sound equipment, and installed a Christie platter film
handling system.
The main fault with carbon arcs
was the maximum running time available which with the current technology
in c~rbons and lamphouse design, was
approximately one hour. A change over
to the other machine was therefore
necessary, to allow replacement of the
spent carbons.
The development of the Xenon arc al-
Flg.2: A Simplex Projector with the
Xenon lamphouse in place of the old
carbon arc. A 'very user friendly'
projector.
lowed further advances in cinema technology to occur. Once struck, the Xenon
arc will continue until the power is
turned off, so the development of 'long
play' film systems emerged.
Platter system
The system that was installed at the
Benalla Drive-in is called a 'platter' sys-
\
Fig.3: A three tier
platter, showing
the film being fed
from the bottom
plate and the
middle plate being
used as the
take-up.
22
ELECTRONICS Australia, February 1995
tern, and over years of use in cinemas,
this has proved to be the best in respect
to ease of operation and film handling.
There is no high-speed rewinding of the
film when the show is completed, which
can cause damage to the film emulsion.
On completion of a screening, the film
can be made ready for the next screening
in less than six minutes.
The platter consists of three or four
l .5m diameter metal plates suspended in
the middle (Fig.3) by a bearing, on an
arm attached to an upright support post.
The plates are placed one above the
other. On the top centre of each plate
there is a set of feed rollers and a speed
sensing arm. Each plate is driven on its
rim by a variable speed motor. On the
upright support post, there are more
rollers and another speed controller.
The film is made up by splicing all the
individual spools of the film together,
with a special type of clear sticky tape in
a specially designed splicer, which trims
excess tape and punches sprocket holes
through the splicing tape.
All joints are butt joints, cut and
joined on the frame lines - not lap
joints, as were used during the era
when cement glue was used. Cement
glue had a habit of coming apart during
a show, unless done properly. The lap
joins were also noisy going through .the
projector gate,. caused an annoymg
momentary loss of focus, and were also
wasteful of film.
The film is wound onto the platter on
its edge, soundtrack down and with
markers on the top edge of the film to
indicate where the joins are (to assist
when breaking the film down again to its
original spools). With the start of the
film wrapped around the centre ring, the
spools are then fed onto the plate, in sequential order until the program is finally assembled.
When the film is ready to be screened,
the ring is removed from the centre of
the spool. The start of the film is taken
up through the feed rollers and the speed
control arm, and fed to the projector
where it is threaded up as normal and
then back to the platter upright, through
the takeup speed controller and back
onto an empty plate where the centre
ring is now placed.
As the projector starts up, it pulls
the film through the feed controller which matches the speed of the film
coming off the 'supply' plate to the
speed required by the projector. Similarly the takeup speed controller matches
the speed of the 'takeup' plate to the
speed of the film coming back from the
projector. On the completion of the
screening, the ring is taken from the
centre of the 'takeup' film platter and the
whole process can be repeated, using
this platter now as the 'supply' and the
original as the 'takeup'; there is no need
to rewind. By reducing the amount of
time that a film is handled, this system
also reduces the possibility of damage.
Cine-fl sound
The Cine-fi sound system was an improvement to the old speaker system
that was originally installed at the Drivein (Fig.4). Cine-Fi used the low level
audio to modulate an AM carrier, set at a
frequency in the broadcast band which is
not subject to interference from local stations or strong interstate stations.
With most Cine-Fi type installations
there was the ability to shift the
transmitting frequency a small amount,
to avoid interference, during nights that
a lot of skip was noticeable. The signal
was transmitted to the cars by a flexible
lead, which was clipped onto the car's
antenna, from the stands on the ramps.
The soundtrack was then received via
the car radio.
Some rows of conventional speakers
were left for people who did not have a
car radio. The main advantages of this
system was the potentially better sound
quality produced by the car radio, plus
less vandalism and damage caused by
people driving off without first disconnecting the speakers. Some speakers
used to have a stainless steel wire in the
lead, and would make a mess of the side
window if you drove off without removing the speaker first.
The greatest problem with this system
was the number of flat car batteries at
the end of the screening. Jump-starting
cars was a common occurrence, particularly during the winter months.
I liked working at the Drive-in
theatres. I had the opportunity of
meeting and talking to the patrons, and
on occasions some patrons would
come to the projection room and ask if
they could have a look at the
equipment running.
The weather sometimes upset a
screening, such as heavy rain or fog.
One night in showing a dusk-to-dawn
holiday screening a fog rolled in, and all
the cars moved as close to the screen as
they could to see the end of the show.
That was all right for them, but I could
not see the cue marks on the screen, and
had to guess the change-over spots. It
must have been a iittle bit disjointed, but
they stopped there until the end...
Another night I started to screen the
spools out of order. When it was brought
to my attention, I rapidly re-arranged the
spools back into the correct order. The
Flg.4: A Cine-fl
sound rack as
used In drive-in
theatres. The
two transmitters
are in the left
rack and on the
right rack Is the
amplifier and
distribution rack
for the ramp
speakers. Note
the 807 output
valves.
patrons must have had a feeling of dejavu as the same scenes were repeated, this
time in their correct sequence!
At the end of the show the job I hated
doing most was going around the theatre
to wake up those who were asleep(?).
From a fair distance away, I would shine
a high-powered torch into the car, thus
saving embarrassing situations to both
the patrons and myself.
Another amazing fact that I have
noticed about drive-in theatres is that
Flg.5: A typical projection room in an automated theatre. The computer can just (
be seen under the left hand edge of the top platter. The projector Is a Bauer U3. ',
ELECTRONICS Australia, February 1995
23./
Hi-tech in Modern Cinemas
Above: A view of the computer, which Is mounted on the
wall between the projector and the platter with the pon
above the unit.
Right: The electron/cs of the computer, with the larger
board at the top being the VO board, the board In the
centre the computer board and the board at the bottom Is
for the LC display.
they are all built in a windy area. I've
lost count the number of times that I
have looked out of the projection room
windows and observed the cars moving
in the wind, even on nights that I considered relatively calm.
Sunday nights at the drive-in were always 'R' rated night, either violence or
sex shows. That was the only night of
the week where I would miss change-
overs, because I was too busy watching
the action on the screen.
The owner's wife was tired of the
violence and sex being screened each
Sunday, and asked her husband what
was screening next Sunday. He replied
'The Big Red One'. "Oh no," she said,
"not another sex show." (The Big Red
One is a war movie, about the
legendary First Infantry Division in
A view of the slide
projector and the
Tascam 133 tape
deck which
sequences the
slides to the
sound track.
24
ELECTRONICS Australia, February 1995
World War 2, and starred Lee Marvin
and Mark Hamill.)
Computer control
Having developed the platter long-play
system and the Xenon arc, the next stage
was to control the screening of the show
by a computer. This is the basis of a
modem 'multiplex' cinema, where up to
six screens (or more) can be run by one
operator. The theatre where I am currently working is only a twin, but the principle of operation is the same as for all
automated theatres (Fig.5).
The computer in the Capri Twin
Cinema, Shepparton is the Model
Ezymation II, supplied by Greater Union
Village Technology. This unit is
designed to automate new or existing
theatres. The method used allows any
person, without previous knowledge of
computers, to enter the program into the
computer. This is achieved by each of
the function keys being labelled with the
traditional terms, with which any projectionist will be familiar (such as 'Xenon
on', 'Motor on', etc.).
The computer consists of four main
parts: a keyboard, a liquid-crystal display
(LCD) screen, a single-board computer
and the input/output (1/0) board.
The keyboard is a flat tactile panel
with 'soft touch' keys, that are used
to enter the program commands into
the computer, or to control the program manually.
The LCD screen indicates the program
status - i.e., at what stage the program
is currently. This is true both when
you're feeding in the program in 'load
mode', or when the computer is running
the screening in 'run mode'.
The single-board computer interprets
the incoming information and controls
the operation of the LCD, as well as the
input/output board.
The 1/0 board has 16 opto-isolated inputs for the various cue sensors mounted
on the slide projector, etc. There are also
40 relay outputs, which can be set for
either normally-open or normally-closed
conditions. In addition there are 16 transistor outputs, which can be used to
drive alarms, or switch external relays,
etc. All 1/0 lines have a corresponding
status indicating LED on the front panel.
The computer can be programmed
quite a distance into the future. One day
when I was trying to correct the computer clock for daylight saving, I accide n tl y programmed a session for
February 27 in the year 2002. It would
be a long wait for the start of that session! The computer can be programmed
for eight sessions a day. Each session
can have a different mix of formats and
trailers (e.g., widescreen trailers and
CinemaScope main feature, or CinemaScope trailers and Widescreen main feature, etc.)
A typical program would be as shown:
Step Description
1
Slide xenon on,
Start sound slides,
House lights preset
2
Stop sound slides,
Start auto-start sequence
(subroutine - see later)
3
Sound to stereo mode
4
Lights to house down
Fig. 7: The slide
projector used at
the Twilight Drive
In Theatre,
showing the old
carbon arc system.
3
4
5
6
Fig. 6: The lens turret assembly of
the Bauer.
Lights to house preset
Auto-stop sequence (subroutine)
The following shows the timing and
steps involved in the Auto-start subroutine sequence:
Step Time Step Description
5
6
(secs)
1
0.0
Sound alarm
2
0.2
Projector xenon on
3
0.4
Masking to Widescreen
10.0 Projector motor on
4
5
13.0 House lights preset
14.0 Non-sync sound to mono
6
15.0 Mute non-sync sound
7
8
17 .8 Slide xenon off
18.0 Picture on screen
9
10 19.0 Cycle slides back to start
And here are the timing and steps involved in the Auto Stop sequence:
Step Time Step description
(secs)
1
2
0.0
8.0
Alarm
Xenon off
8.2
8.6
9.4
9.6
Picture off
House lights up
Non-sync sound on
Masking back to
widescreen
What all this means in plain English is
that when the computer is first switched
on at the start of the day, the display
screen indicates that the first command it
issues is for the house lights and the
non-sync sound (which is a six-pack CD
player on random play) to come on. This
step is programmed to occur 15 minutes
prior to the start of the day's screening.
At the programmed starting time, the
computer starts the slide machine, fades
the non-sync sound down and brings up
the sound of the tape deck with the prerecorded cinema advertising. The slide
projector that is used in this theatre is a
35mm carousel projector modified to accept a 550W Xenon bulb as its light
source. The carousel is stepped by prerecorded tones on the tape. At the same
time the house lights are dimmed to a
preset level.
When the advertising slides have
finished screening, a pulse is sent to the
computer to initiate the next stage,
which is the Auto-Start sequence (see
above). In the next 19 seconds the sound
is faded down, the Xenon lamp on the
projector is struck, screen masking is adjusted and the projector motor is
switched on. The film starts moving
through the projector and at the end of
the lead-in film strip, another cue mark
activates the computer to the next step.
The slide carousel Xenon is extinguished
and the shutter on the projector opens,
putting the image on the screen. The
sound is also switched from the tape recorder to the film soundtrack.
Cue marks are placed on the film to
signal to the computer when it is to initiate the next step - which in this case
is to extinguish the house lights at the
end of the trailers/film advertisements,
and if the main feature is in the CinemaScope format to open the screen masking, and also change the lens and the
aperture plate.
(Unfortunately our projector is not
fitted with an automatic lens and
aperture plate changer. This procedure is
carried out in the low-tech way: we
change the lens/aperture plate manually,
and can do this while the show is running in three seconds. The patrons do
not notice this, as it is done between the
fade-out of the trailers and the lead-in to
the main feature.)
The next cue mruic is placed at the end
of the feature, just as the credits start.
Continued on page 101
ELECTRONICS Australia, February 1995
25
Preparing for a crowded Clarke belt:
At the time of writing, the prototype 3.6 metre multibeam antenna was currently operating with only one feed horn. Site:
CS/RO Radiophysics section, Marsfield, Sydney.
CSIRO'S LEADING EDGE
MULTIBEAM SATELLITE DISH
One of the inevitable consequences of the growth of satellite communications and broadcasting is
that more and more 'birds' are being placed into orbit. Things are getting crowded up there, and this
is causing complications for anyone who needs to send to, or receive signals from, satellites.
Steerable antenna dishes are expensive, and multiple fixed dishes clumsy as well. The answer is
one dish capable of focussing on a number of satellites at once, and Australia's own CSIRO is playing a leading role in the development of these antennas.
by BARRIE SMITH
In terms of satellite communication,
Asia is the place to point your dish to:
the geostationary orbital arc covering
this region spans 130° - and in it there
will soon be no fewer than 51 satellites,
some as close as 2° apart.
With a traffic jam developing 'up
26
ELECTRONICS Australia, February 1995
top', here on earth things are not
much better as more and more organisations, both government and corporate, find the need to communicate
with the satellites above us, planting
dish antennas across the cityscapes
and countryside of the globe.
Pay TV operators, relying for the
major part on satellite delivered
programming, often kick off
their activities without actually
locating a receiving dish antenna on their property. A local example of this is Sydney company
CTS, who rely on satellite feeds from
another company.
In Forth Worth in Texas, there are
about 30 large dishes on one site all pointing in different directions and
redistributing the signals to organisations across the US. Called a
'teleport', this type of facility will be
seen more and more as satellite communication explodes.
Smaller dishes (2 - 3m) are now
springing up even in Australian suburban backyards and atop city buildings.
As Pay TV becomes a reality, we will
hear not only the anguished cries of the
visual environmentalists but the sound
of descending wrath from our local
councils as the landscape becomes festooned with the 'white woks'.
The answer to the problem is already
present in the form of multibeam dish
antennas, able to receive/transmit from
and to multiple geostationary and low
earth orbit satellites.
In the US there is one company actively engaged in the manufacture of
multibeam antennas - Antenna Technology. In Japan, a multibeam dish
operates off a Ka-band domestic satellite. It is believed there are only two or
three of this type in existence.
Australian initiative
For a change, Australia is in the
forefront of this advanced technology,
with our own version of a multibeam
antenna. Developed by the CSIRO, this
device is still a prototype, so manufacturing is a stage yet be reached.
Dr Trevor Bird is Research Manager
The CSIRO's multibeam antenna allows multiple feeds to be used with a single
main reflector and subreflector, to receive signals from or transmit signals to
multiple satellites.
on the Electromagnetics & Antennas
Program within the CSIRO's Division
of Radiophysics at Marsfield, Sydney.
In his view, with so many birds already overhead, the 'one satellite, one
earth station' approach is wasteful for
many reasons - leaving him with the
opinion that "more elegant solutions
are needed".
CSIRO development work began on
In constructing the multibeam antenna, the design took into account that
neighbouring panels differ in shape. To mould the aluminium panels a novel
adjustable mould was used.
the multibeam antenna in 1985, when
the organisation was asked by AUSSAT
(now Optus) to come up with an earth
station antenna that could simultaneously access the three satellites envisaged
to cover this country.
Dr Bird relates that "We looked at
retrofitting, so that you could actually
have three feeders in one reflector.
That works for receive only and for
small dishes. But to get the best performance, you end up with a fairly
complex feeder and you are still only
able to access satellites spaced a
couple of degrees apart."
"In the AUSSAT (Optus) scenario
you would get something of the .order
of about a 1 - 2.5 metre dish, which
would allow you to access all three
satellites. But if there was another part
of the segment in Australia that had
three satellites, you would have to
repaint the dish."
"So then we started looking at alternatives. One was a torus, shaped like
part of a donut - circular laterally, and
parabolic in the vertical direction."
The CSIRO work group felt there
were a number of disadvantages with
the torus, aside from its lack of efficiency. Compared with conventional
parabolic reflectors that have aperture
efficiencies greater than 50%, a torus is
less than 20% efficient.
The search was then on for other
methods offering higher efficiency, but
ELECTRONICS Australia, February 1995
27
CSIRO's Leading Edge Multibeam Satellite Dish
with maybe not as wide a field of view
- that was the trade off.
Dr Bird: "The geometry we looked at
was a two reflector system, where both
reflectors are shaped. Just as with ordinary spectacles, where to overcome
astigmatism you can shape the lenses
to improve the focussing properties of
the eyes, the reflector surfaces are
shaped to be able to take beams from
a range of directions and to focus
them - but they won't be an absolute
point focus as they are in a parabolic
reflector. Its operation is similar to a
collector lens."
'The two-reflector arrangement
means that instead of having a single
focal point, a focal surface or 'hot
zone' is created - so by moving the
feed anywhere within that zone, you
can receive/transmit a signal with
high efficiency.
While Dr Bird admits that the concept
was not 'invented' at CSIRO, his
group's contribution has been to
demonstrate that in fact the approach
works, theoretically and practically.
Another contribution has been to come
up with the focal surface, which is ideal
for tracking satellites in inclined orbit.
The earlier two-reflector antenna, like
the torus arrangement, is designed to
work best when the satellites lie along
the geostationary arc.
Nowadays, many satellites are not
fixed in geostationary orbit, but are allowed to wander.
One example is the Optus A2 satellite, which is in an inclined orbit of
around 1.5°: from the ground it gives
the appearance of going through a 'fig-
A custom designed steerable feed horn, placed In the focal surface or 'hot cone'
of the antenna. Up to 20 could be accommodated in a production model.
ure eight' in one day. An operator is
compelled to keep on trimming the
ground antenna's pointing direction to
keep its signal high.
With a conventional antenna you
move the whole antenna to follow that
satellite; with the multibeam one of
the feeds is moved to follow the
moving satellite. So, in principle that
means if you need to access six satellites with six feeds, some of them may
be fixed and some of them may be in
inclined orbit - so you can install a
mechanism to drive the feeds that are
required to track.
Dr Bird explains: "At the moment we
A satellite antenna under test in CSIRO's near-field test
range In Marsfleld, Sydney.
28
ELECTRONICS Australia, February 1995
are testing a prototype of the multibeam
and have devised a technique for
moving one of the feeds. This
mechanism can be used to track one
satellite or it can be driven around
anywhere within the focal surface to
pick up any other satellite that you may
wish. If flexibility is a major requirement, you could sit there and dial in the
required direction and the feed will
move to that satellite."
Currently, there is one automatic
feed in the antenna, but CSIRO has
had three fixed feeds installed at one
time. One demonstration saw two of
the Optus satellites on tap, as well as
The performance of one of the feed horns used in the
multibeam antenna being measured using the CSIRO's
instrumentation.
a signal from the Intelsat satellite about 15° away.
With the current prototype, the feed
capacity depends upon the inter-satellite
spacing. With 1° separation a total of 20
satellites could be accessed. The
antenna's horizontal field of view is 23°
along the geostationary arc, permitting
a tolerance of +/-1.5° on either side.
The dish can also 'look' at satellites
which move +/-3° out of the geostationary arc, before the whole antenna would
need to be moved.
Perceived markets
The original market for the multibeam antenna was seen as the Teleport
area similar to the Fort Worth operation,
Dr Bird explained, where the operator
provides links to outside companies.
"I think that will happen here too",
Dr Bird predicts. "You have only to
look at how quickly the number of
satellites has grown over this area and
in Asia."
"A major obstacle is that with all
these dishes sitting on buildings, it becomes a bit of an eyesore. The current
scenario is to have six dishes to access
six satellites; contrast this with an approach where one dish can accommodate six feeds. In the situation that
applies in Sydney, we could cover the
whole of the sky with three dishes."
As far as Dr Bird is aware, the only
firms c\irrently offering a multibeam in
the marketplace are Antenna Technology and the Japanese company.
Current market
There has been a tremendous amount
tslRO's mMe~m
principle
The antenna consists of two reflectors
in an offset Cassegrain configuration plusan array of signal feeds, each viewing a sefected satellite. In the conventional antenna the feed ·must be
positioned at a single f9<;al point; the
CSIRO multibearn .bai ,a 'focal. surface'
on whicli: upto.20 feeds can be placed.
In the ca$eofthe·3.I) metre
···
this focal s1.1rface area spans
1.5 met~s. The · An~en
ogy mQdel is~
view than the CSI
ly ·60", but prod
point fn the us de~!Sn:; . tlft the gain
by 20% you wouttfneed to double the
size of the dish.
Thernultibeam. uses. !jpe(:ially shaped
reflecto~; Strategicitfly µoSitioned to
broaden.the scan region along the geostationary arc.
··To track satellites with this antenna,
only tli:e feeds need be moved, rather
than the . entire strucrureof the dish. The
multlbeam can comrn1.1nicate with a
number of satellites within one degree
of each other.
· ·
The CSIRO would prefer to work
with an Australian company to bring the
multibeam to fruition by licensing the
technology. And as Dr Bird, explains,
this could happen soon: "We've had
some discussions with a couple of companies; one in particular is very inter- ·
ested and they're waiting to hear the
outcome of test results on the present
feed movement apparatus."
Development resources
Some 'substantial' computer software
was used to design the antenna in the
first place, Dr Bird explained, but the
CSIRO would never have reached as far
as it did without the financial support of
the Department of Defence, who have
seen the commercial possibilities of the
antenna as well as its suitability for
their own activities.
Aside from the CAD work executed
by the CSIRO, the feed movement
mechanism and the basic idea and
concepts behind it were developed in
conjunction with a company in Melbourne, Invetech. The Division of
Radiophysics built the dish itself in
their substantial workshops.
The early 1980's saw the Division
of interest in the Australian develop- design and construct the Australia
ment, but the limiting factor is that as Telescope's seven-dish array at Naryet the CSIRO have only reached rabri. During this activity the Division
prototype stage.
developed a technique for producing
Dr Bird is of the opinion that, if a low cost reflector panels, that has since
production model had been available, a been used in over 40 earth stations built
number could have been sold already: here and overseas.
"We've had several enquiries from.
This panel technology smoothed the
overseas suppliers, but getting the path to constructing the dish for the
finance to progress from the prototype multibeam. In the latter the technique
to manufacture is difficult."
has been automated to produce panels
The Radiophysics Division of CS/RO has extensive
workshops. Here a waveguide 'twist' s8ctlon Is being
machined.
A drawing of an Optus section generation 8-serles sate/lite,
showing the L-band array on the front face, spot beam
antennas on the west face (right) and the national beam
antenna on the east face (left). The small WA spot beam
antenna on the bottom right was designed by CS/RO's
Radiophysics.
ELECTRONICS Australia, February 1995
29
The Dawn of
Australia's
RADIO
Broadcasting
One of the latest books to
be published under the banner of Electronics Australia.
Written by Philip Geeves,
OAM, FRAHS, almost 10
years ago, it transports the
reader to the beginning of
broadcasting and outlines the
roles played by technical
pioneers, religious sects, individual personalities and
politicians.
Mr Geeves' writing reflects
the vast amount of historical
knowledge and experience
he had gathered during his
years in the industry.
Many of the illustrations
have been provided by AWA,
a firm which played a key
role in building many of the
first radio stations.
Copies may be obtained by
forwarding a cheque or
money order to the value of
$7.00 (this includes postage
and handling), to:
The Book Shop,
Federal Publishing
Company,
P.O. Box 199,
Alexandria, NSW 2015
30
ELECTRONICS Australia, February 1995
CSIRO's Multibeam Satellite Dish
of different shapes. In a conventional
antenna adjacent rings of panels are all
the same; with the multibeam, neighbouring panels may differ in shape. The
CSIRO's approach uses an adjustable
mould, rather than a series of moulds to
form the aluminium panels.
From initial planning the development of the prototype took about three
years of elapsed time. Design, construction and testing took about 12
months, preceded by 18 months for
the electrical design. Dr Bird admitted
"We had to prove to ourselves and also
to Defence that the software gave sensible results".
Capabilities and potential
In Dr Bird's view, many operators
plan their satellite links on a 'one satellite, one earth station' philosophy. But,
he argues, "If you had a multibeam arrangement built into the networking, the
cost could be amortised and benefits enjoyed through possible efficiency gains
in the network's operation. The other
factor is that costs fall for fairly large
antennas used in the multibeam configuration - the bigger, the cheaper."
"Once you get above say around 12metre antennas, which are very expensive to construct, just adding another
feed adds little to the cost, compared to
the cost of a whole new antenna."
One possibility is that the principle
could be used in terrestrial systems, particularly at very high frequencies. At
millimetre-wave frequencies, the
propagation path can't be guaranteed
because of rain storms and so forth, so
by using diversity systems you'd be
able to get the signal through. One
transmitter could be placed at one site
and another at a distance; then a multibeam with two feeds could be pointed
in those directions, allowing the system
to select the optimum signal.
And the cost?
Dr Bird explains about cost: "Because it's new technology, it's obviously
more expensive. In fact it's only in the
'boutique' or specialised end of the
reflector market, where you would see
the cost reductions immediate! y. ''
"But, if it were to be made using
cheap or mass production type techniques, I'm sure the cost could be
reduced to be comparable to conventional dishes - but the numbers
would have to be significant, to cover
the cost of tooling up for what is a
fairly specialised antenna."
At present the auto tracking control is
an outside unit, because it's such a big
system. The 3.6-metre unit presently
being trialled is at the lower end in size.
It would be possible, Dr Bird surmises,
that you could incorporate control
facilities into the antenna itself, consisting of a computer driving the six
motors needed.
Because the multibeam is a fixed
structure it resembles a building unlike a conventional antenna which
has to move.
Cost savings would be likely; changes
in the ground or building surface are
compensated for, to a large degree, by
the feed movement mechanism.
Related activities
The Division of Radiophysics has, in
the past, handled a considerable amount
of work for Telstra (formerly OTC), and
completed much of the electro-magnetic
design for their earth stations, moving
on to general work for other earth stations in Australia.
One of these was the complex feed
system for the Tasmanian Earth Resources satellite, operated by the CSIRO
Division of Oceanography that collects
data from the low earth orbit earth
resource satellites.
The Division does work on antennas
for space applications as well as those
on the ground. For example, it has
designed and tested the WA spot beam
antenna for the Optus satellites made by
Hughes US.
The CSIRO was involved in the
preliminary design for Optus prior to
the contracts going out to tender, following which Hughes commissioned
the Division to design one of the antennas. More work has ensued, for
one of the US beams, as well as consulting activity.
In Dr Bird's opinion his group's main
area of expertise is antenna analysis and
design: "We're in the forefront in that
area, as far as the research activities go.
The onboard satellite area is a
very fruitful sort of area for new
ideas. It's not a big area but, because
we have expertise in it, we're hoping
that when Optus come to do another
satellite in the year 2000, or so, we
would like to be in there again making
our contribution."
In closing, the author ~ould like
to thank Dr Bird and his associates
for the considerable cooperation
given by them in the preparation of
this article. +
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VICTORIA'S SCHOOLS
LINKED BY SATELLITE
Late last year saw the official launching of Victoria's Interactive Satellite Television (ISTV) network,
which links 2500 of the state's government and independent schools to deliver a wide range of
educational services - including language and science and technology programmes. Bayswater
firm Melbourne Satellites were jointly awarded the contract to supply, install and support the school
satellite terminals, and this along with other Victorian projects has helped the firm achieve dramatic
growth.
·
by JIM ROWE
When Victorian Premier Jeff Kennett
officially launched his Directorate ofSchool Education's ISTV Network late
in August last year, it was the culmination of a three-year project which had
cost $3.8 million.
In the process, not only had Victoria's
school students and teachers gained access to a highly effective medium for
distance education via interactive satellite TV, but the state's fledgling satellite
TV industry had also received a very
·
welcome boost.
Bayswater firm Melbourne Satellites
had been awarded roughly half of the
contract to supply and install the ISTV
school terminals, with the other half
having been awarded to fellow Melbourne firm Mobile Television En-
gineering. And Melbourne Satellites
MD Mick Cameron says that the ISTV
contract, along with other projects, has
allowed his firm to achieve dramatic
growth.
In 1993 it had only 3-4 employees
and a turnover of around $250,000,
while 1994 saw its employees grow to
over 20 and annualised turnover to
around $3 million.
The project hasn't been of benefit to
only the two firms directly involved,
either. As much of the equipment and
materials required (like antennas and
steel mountings) were sourced from
other local firms, there's been a significant 'trickle down' effect.
Of course the prime beneficiaries of
the ISTV project have been the students
A motorised prime focus dish antenna mounted on the roof of a Victorian school,
linked Into the /STV network. The system makes use of the Optus A3 satelllte,
and much of the equipment and materials used were sourced locally.
32
ELECTRONICS Australia, February 1995
in Victoria's schools. Centrally
proquced language, science and technology programmes can now be .
beamed directly to the schools, where
the students and teachers have been
able to interact with the presenters via
telephone and fax.
To date, the network has offered
primary school programmes in science
and technology, Indonesian, Japanese
and Italian. This year, it's planned to
provide a similar range of programmes
for secondary schools, along with
professional development and training
programmes for teachers.
Each of the 2000 government schools
and 500 independent schools linked to
the network either has, or will shortly
have a Ku-band (12.25 - 12.75GHz)
satellite terminal based on a Pace
IRD50 integrated receiver/decoder, fed
from a 0.9dB noise figure LNB (lownoise block downconverter) and a 1.5m
dish antenna.
Most of the LNB 's are Gardiner
single polarity units, while the dish antennas are ESA13-15 units from
Andrew Australia, with Az/El mounts
and offering 44dBi gain. The ISTV Network operates on the Optus A3 satellite
at 156° East, using transponders 5 and 7
with vertical polarisation.
·
Already, the ISTV project has been
hailed as a major educational success,
and may well expand from Victoria to
most other Australian states. By late in
1994 some 200 schools in the other
states were testing the system. The
NSW and Victorian governments are
apparently negotiating a co-production
agreement, which if concluded could
result in programmes being originated
in both states, this year.
Overseas educational bodies such as
Indonesia, The Philippines and France
have also shown considerable interest in
The Melbourne Satellites team installing satellite antennas on the roof of the
Army's College of TAFE in Bonegilla, Victoria. The College's two Ku-band
systems and one C-band system are used to train soldiers in satellite
communications technology.
the Victorian initiative, and some of the
English-language programmes may be
exported to these countries.
In short, the ISTV Network is a great
success, and an important achievement
by not only Victoria's Directorate of
School Education but also its burgeoning satellite communications industry
- and firms like Melbourne Satellites
in particular.
For further information on the ISTV
project, contact the Learning Technology Staff, Quality Programs Division,
Directorate of School Education, GPO
Box 4367, Melbourne 3001 or phone
(03) 628 4008.
Melbourne Satellites has also recently
supplied and installed three satellite
receiving terminals at the Army's College of TAFE in Bonegilla, Victoria.
Costing over $20,000, the terminals are
being used to train soldiers in satellite
communications technology.
One system is for C-band reception,
with a 3. 7m Orbitron mesh dish on a
two-axis motorised mounting feeding a
Drake 700e receiver and capable of
receiving Intelsat, Gorizonts or Palapa
satellite transmissions; the other two are
for Ku-band reception and use 1.8m and
l.6m dishes.
For further information on the range
of satellite TV equipment available
from Melbourne Satellites, contact the
firm direct at 82 Bayfield Road (PO
Box 901), Bayswater 3153; phone (03)
738 0888, or fax (03) 729 8276.
Our thanks to Mick Cameron of Melbourne Satellites for his help in preparing this story. +
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When I Think Baik•••
by Neville Williams
Archie Caswell: radio dealer, serviceman, 'ham'
and a modest hero in Japanese POW camps - 2
A local radio dealer and repairman in Queensland during the 'Golden age of radio', Archie Caswell
joined the RAAF but ended up as a prisoner in a Japanese POW camp. There he defied his captors
by contriving illicit radio receivers, and boosting the morale of his fellow prisoners by intercepting
news from allied short-wave broadcasters.
We begin this second part of the Archie Caswell story by letting Archie
continue his own account of life in the
POW camps:
Life in the Prison Camps was studded
with rumours, some to do with the war in
general, others to do. with matters that
might impact on the prisoners' own
situation - including our access to radio
news broadcasts!
For us, one notably persistent rumour
was that we would be transhipped from
Java to an unknown destination. As it
gained momentum, we decided that the
radio facility had best be rendered
'mobile', so a second fake water bottle
was prepared to accommodate key
spares, including a headphone and a
spare valve.
The spare torch cells posed a problem
of bulk and weight, but the many empty
M&V (meat & vegetable) cans around
the camp gave rise to an idea. Two such
tins, cut around the middle, could be
fitted together to look like an unopened
can. A circular tin sleeve soldered on the
inside would ensure a neat fit and the
original label could be re-glued around
the circumference to hide the join.
As I remember, the 'doctored' tins
held seven torch cells each, which had
to be carefully insulated from the top
and bottom of the can. The weight was
about right, and quite a few such tins
were prepared to ensure a continuing
source of power.
The one disadvantage was that they
became quite heavy on a long trek, as
Bill Wilkinson (RAAF) later discovered,
when he subsequently inherited the job of
carrying quite a few of them.
The second fake water bottle was to be
34
ELECTRONICS Australia, February 1995
carried by Bill Breillat, while I would
look after the radio and aerial. Little did
we realise then that this 'mobile' outfit
would ultimately travel from Singapore
to Burma and Thailand.
As it was, the new receiver had an extended tuning range and passed all tests,
news being received from San Francisco,
the BBC, All-India Radio Delhi, and
Radio Australia Melbourne.
Because we had to conserve batteries, it was decided that the best
regular bulletin was from the BBC
Far East transmissions. There were
times, however, when it was not possible
to listen because of lap guards, camp
shifting etc. For the most part, listening
had to be done in the dark and notes
made on paper, which took some
deciphering in daylight.
Time to move on
The precautionary measures certainly
paid off when rumours of an impending
shift proved to be true: within a few
weeks, we were to leave the 'Bicycle'
Fig. 1: Archie Caswell, photographed just before his retirement at the test
bench of his shop in Adelaide Street, Maryborough. He had been involved in
television from its establishment in Australia in 1956, when he discovered
that signals from Melbourne could be received in Southern Queensland due
to anomalous 'skip' propagation.
Camp, Java - destination unknown, but
perhaps Singapore. The day came and
we were loaded into a lap cargo vessel
(bought from Britain pre-war as scrap
metal). The space per person was two
square feet per man, which made for a
rather 'cosy' crossing of the equator!
After quite a few days of hell, we
reached Changi camp in Singapore. This,
we soon learned, would be only a staging point, so the radio was not set up.
Moreover, someone else at Changi already had a hidden radio and news was
being received.
A couple of weeks later, we were
herded into a cattle boat and on our
way again, this time on a longer and
more arduous journey - the conditions
filthy and the progress slow - and
with everyone sweating it out under the
steel deck plates until Rangoon, Burma
was reached.
Someone on board had a compass and
could check our direction of travel. We
reasoned that we must be nearly there,
when a deck party saw the muddy water
of the Irrawaddy Delta.
There followed a slight respite - of
one day - and we were on our way
again from Rangoon to Moulmein,
Burma. Here we were marched off the
ship to the Moulmein jail. An ever to be
rembered sight was the 'Golden
Pagodas' glistening in the sunshine, followed by the sets of stocks just inside the
jail gates, and the rack and other
medieval means of torture.
This gave us cause to think hard, as
also did the sight of primitive Burmese
tribesman prisoners walking around the
courtyard with heavy chains around their
ankles and holding in their hands a
heavy iron ball chained to their ankles.
That night, we nevertheless decided to
throw caution to the winds and set up the
radio, receiving two news broadcasts.
Burma/Thailand >railway
Within 48 hours, the move was on
again and we marched away through the
outskirts of Moulmein to a place named
'Thanbiziat', which was eventually to become the Burmese terminal of the infamous Burma/Thailand railway.
On the march, we were most impressed by the friendliness of the Indian/Burmese population, who tried to
give us food, towels, clothing and
books, risking the every-present chance
of a good Japanese flogging. Many of
these people spoke fluent English and
were obviously well educated.
The radio was re-commissioned
during operation Thanbyuzayat Burma
but, applying our Java lesson, all news
went only to a senior officer, who arranged distribution.
A week or two here, and many
Japanese indoctrination lectures later,
saw us off again some 40km into the
jungle towards Thailand. We were indeed
going to build a railway, of which much
has been written.
Some weeks passed during which the
radio intercepted many cheerio calls
from relatives in Australia and as reception occurred in darkness, quite a few
messages were delivered to POWs from
their familes Down Under. This boosted
their morale and gave them some hope.
Unfortunately, over-talkative individuals in our midst were still less
than discrete in discussing such matters, and the Japanese were becoming
frustrated because they could not find
the radio they thought we must have
access to.
A change in strategy was clearly
called for when it became evident that
water bottles were being used freely by
many POWs to conceal watches, jewel1ery, etc that they had managed to
scrounge. The Japanese were walking
through our huts saying: "Changee,
changee, ten rupee for watch, compass,
radio, etc".
They had even stripped our camp of
old lengths offencing wire, in the search
for radio equipment. What if a curious
guard chose to examine one of our two
'radio' water bottles?
Seat of the problem!
After some discussion, we decided
to make a wooden kitchen stool with
a false bottom and conceal the radio
and batteries there. (For Archie, it
was also a place where he could conceal his war diary).
The ruse completely fooled the
guards, who frequently sat on the stool
F/g.2: Having defied
his captors In
Japanese POW
camps at great risk
to his life, a once ordinary country radio
serviceman set
about rebuilding his
life In this equally ordinary radio shop In
Adelaide Street,
Msryborough,
Queensland.
aECTRONICS Australia, February 1995
35
.
when searching our gear. When shifting
camp, the stool would be loaded with the
kitchen gear and away would go the lap
guard on the back of the truck - sitting
on the stool! Needless to say, the opening
was nailed shut when a move was on.
As the months dragged by, we shifted
back to the 26 Kilo Camp in Burma, then
off again to the 55 Kilo Camp and then
to 75 Kilo and on to the 105 Kilo Camp,
which was just outside the Thai border. It
doesn't sound much when you say it
quickly, but it represented 18 months of
life in the jungle.
The radio still performed well, in spite
of the humidity. Unfortunate/y, as the 105
Camp, we lost our good friend Frank
Huxham with dysentery.
The railway line was now finished.
Other parties had been working from
Bangkok and when the last rails were
laid, we watched the spectacle of
Japanese troops going north and
wounded going south. Japanese
propaganda was intense at the time, but
they couldn't fool us. It was evident that
their time was beginning to run out.
However, the constant humidity was
taking its toll on our stock of batteries;
what else could one expect after four or
five months of continuous rain?
Eventually the rain cleared, but our
power supply was in poor shape. Brian
suggested that we replace the battery
paste with a mixture of sat-ammoniac
and rice flour. Some cells were duly rebuilt and rejuvenated, although rendered
very messy to handle.
WHEN I THINK BACK
buried it in the kitchen. It is probably still
there today!
In conclusion, we must remember that
this project, like many others, could not
have made itself worthwhile without the
effort of many people who, working as a
team, ensured its successful operation.
Arch Caswell concludes his memoirs
with the sentence: My gratitude to all
who contributed.
To that I should add my own word of
appreciation, for the effort he made to
record the events for posterity. As Darryl Kasch remarked to me over the
phone: "Arch wrote what he did only
because he was prevailed upon to do
so. He confined himself to the basic
facts, anxious to avoid any fuss about
events that he would have preferred to
put behind him".
Archie Caswell, postwar
In the taped interview, Archie's wife
Desley said that when the War ended in
August 1945, priority for transport back
to Australia understandably went to those
POWs whose physical condition was the
most urgent.
Archie did not make it back until October, but even though he had been
looked after in the meantime, he still
weighed only 6-1/2 stone. His health
was 'not good' and he had to be
cautious about what he ate. On arrival,
he was immediately admitted for a
repatriation hospital 'check-up'. His
doctor warned him that the effects of
extended malnutrition would probably
linger for the rest of his life, and that his
treatment would continue for as long as
it took to confirm his pension rights followingdischarge.
When he ultimately did return home
with a pension of ten shillings ($1.00)
per fortnight, he was impatient to pick up
his business life where he had left off
and start a farriily. The Caswells had two
daughters, Jennifer and Lyn.
Archie's attitude was simply that his
POW experience had cost him the best
part of four years, and he wasn't about
to extend the loss by dwelling on the
past. He'd prefer to 'black it out' and
carry right on.
In fact, Desley says, he made light of
medical advice to 'make haste slowly'
and may well have overdone things applying himself to his business, postwar
- 'head down and tail up'!
The one person he would stop and talk
to about the war years was his old buddy
Fl.Lt. Ken Smith. It was Ken who perhaps more than anyone else, alerted his
family to the fact that Ken had a story to
tell, and who finally constrained him to
put pen to paper.
In the meantime, Archie had been
awarded the British Empire Medal by the
Governor General (Mr McKell). The
citation- read:
Caswell, when captured at Java, displayed considerable initiative by building from scrap components a wireless
set. He operated this under great dif-
Made life bearable
The crisis proved a point, however: it
demonstrated that the radio did boost
morale and dissuaded many from attempting escape into the jungle. We knew
that the nearest Allied forces were 400km
away, and no one could be that lucky to
escape and remain undetected.
The few that did try to escape were
brought back to camp and either shot
or beheaded without any semblance
of a trial.
It must have been 1944 when we again
shifted camp, this time into Thailand,
and down eventually to Tamarkan, where
we were greeted by old friends.
On entering camp our Commanding
Officer told us that it was time to give
the radio up, as the Japanese Kempi
Tai (Military Police) were active and
we had pushed our luck long enough.
Some Englishmen at a nearby camp
were operating another secret radio, so
1 surrendered ours to Smithy who
36
ELECTRONICS Australia, February 1995
Fig.3: Arch Csswell's amateur radio at the rear of his home. Note the Reiss
carbon microphone, surmounted by the cal/sign VK4CB.
fu:ulties and the threat of severe punishment if he were caught. He worked the
set continuously to supply a news service to all his comrades.
These services were continued when
he trans/en-ed to other camps, by smuggling the radio with him.
Newspaper report
In reporting the above, and presumably
quoting from official records, the current
Maryborougli Chronicle explained:
At the end of this course (Radar at
Sydney University) he was sent to Singapore to install radar equipment in
Lockheed Hudson aircraft, and posted to
No.I Squadron.
After three months in Singapore, the
squadron was transferred to Sumatra
about a week before capitulation. Here
the squadron continued operations
against the Japanese on the Malay
Peninsula. The squadron at this time
operated from Palembang, in the south
of Sumatra.
Mr Caswell modestly remarked
yesterday that when he heard he had
been awarded the British Empire
Medal, he was surprised.
To date, he has not received any information about the award other than what
he read in the paper.
Darryl Kasch was given to understand
that Archie did not display or talk about
the medal, nor would he have welcomed
suggestions that his activities could provide the central theme for a book on forbidden radios in the POW camps.
Did he know the celebrated Dr
'Weary' Dunlop? According to his wife
Desley he did, although not so much as
a Dr/patient.
Knowing that Archie needed time, on
occasions, to work on the radio project,
Weary Dunlop would conceal him
amongst the men who were 'obviously
too sick to work today'. Once the guard's
back wa'i turned, Archie would head for
the soldering iron!
Author Bon Hall, himself a one-time
RAAF Flying Officer and POW in
Burma, had seen at first hand the efforts
of Archie and others to intercept and disseminate news to the many thousands of
prisoners in the adjacent POW camps.
In a separate article in the
Australasian Post (28/8/1960) Bon Hall
- himself a former RAAF officer and
POW - said that to be caught with a
radio would have involved collective
penalties for the prisoners generally and
an automatic death penalty for those immediately involved.
Summing it all up, Darryl Kasch, who
collected the relevant material, remarked:
"Archie Caswell obviously wasn't a
medal man!"
First and foremost, he was an industrious country radio retailer, intent on
rebuilding a business based on post-war
receivers and providing for his wife Desley and two daughters Jennifer and Lyn.
Desley says that she was very much a
part of the enterprise, standing in at the
shop, answering the phone and looking
after the books.
Roving around
Integrated with the shop was radio servicing, involving calls up to seven days a
week, with distant jobs shuffled to the
weekend so that out-of-town journeys
could be converted into family outings.
Archie also had a shared interest in new
car sales, and last but not least, remained
a keen amateur radio operator with but
special mention because it provided a
'fun' way for Dad to 'double' the kids to
school - this in the days before strict
road rules about safety helmets, etc.
By the middle 1950's, the family
doctor was becoming more urgent in
his warnings to Arch Caswell to slow
down, and to Desley his advice made
good sense. So when a local estate
agent mentioned that a radio
dealer/repairman 'Les' - himself an
ex-serviceman - was seeking to re-locate in Queensland, Desley prevailed
upon her husband to sell out.
Her aim was to break the tight cycle
of committments in which they were
enmeshed. If Arch chose later to
resume his radio activities on a less
hectic scale, so be it. In due course the
documents were signed and the business changed hands in 1956.
'Spare time' servicing
DX on 144MHz...
Writing in the Maryborough
Chronicle, Bill Rendall emphasises that
Arch Caswell's success in snaring signals from Melbourne's Channel 2 TV
station was not a matter of chance.
Some years before, he had maintained a nightly schedule with another
amateur station - 4)0 at Clayfield
Brisbane - to demonstrate that reliable contact was possible on 744MHz
using the relatively low power of 20W.
Arch reasoned that with a much
more powerful signal of lower frequency, a lofty directional antenna .and a
path free of intervening mountains,
there would be a good chance of the
TV signals reaching the Maryborough
area. They did!
one reservation in the immediate postwar period: he would rather 'pull the big
switch' than stay around and respond to
an amateur with a 'JA' (Japanese)
callsign. Funny about that!
The post-war business was based at a
shop in Kent St, Maryborough but, following a flood in 1955, he transferred to
a site in Upper Adelaide Street. Competition in the town became quite fierce, according to Darryl Kasch, with Keers
Radio across the street pushing Philips
products against Arch Caswell handling
mainly Astor, with a sprinkling of other
brands including Tasma and Breville.
As such, the business proved quite successful. According to wife Desley, they
were both busy and didn't make a fortune - but neither did they want for
anything. They employed a youth, Jack
Lloyd, to help out and operated a utility
and a Vespa motor scooter for delivery
and service work. The scooter rated a
In fact, Arch never did re-launch into
radio sales and service at a serious level,
but neither did he drop out of radio altogether. He did a few repair jobs 'to
keep his hand in' and showed a special
interest in ageing receivers which were
in the process of becoming historic or
'vintage' models. He had also taken up
lawn bowls, which he had pursued to
championship level.
And, of course, out the back he had an
array of amateur radio equipment and
motor-driven rotating antennas, atop a
?Oft (21m) mast. Desley recalls that the
girls used to come in and observe that
"Dad's talking to his girl friend again up in the Canary Islands"!
That same mast brought a new and
compelling interest into his life when the
ABC TV stations in Sydney and Melbourne opened in November 1956, in
time for the Melbourne Olympics. To his
delight he found that, under certain atmospheric conditions, the signal - particularly from Melbourne - 'skipped'
through to the Maryborough area.
So Arch bought himself a standard
Australian TV set (did somebody say
Astor?) and set it up in his home.
When signals showed up on the screen,
the word would go out and friends and
relatives would converge on the Caswell home for free entertainment.
Sometimes they would see a whole
show; at other times there would be a
loud 'Hisssss' and the picture would
dissolve into nothingness as the skip
path disappeared.
The exercise also meant that Arch
was able to gain an early familiarity
with television technology, as
employed in the initial wave of
Australian B&W receivers.
ELECTRONICS Australia, February 1995
37
.-
WHEN I THINK BACK
As TV services were extended into
Brisbane in the following years, intending viewers in the Maryborough area
faced the option of installing 'fringe'
TV antennas on lofty, guyed masts,
much as happened in the Newcastle
area ofNSW.
Fringe area TV
Arch Caswell responded by setting
up the family caravan on an accessible site and providing it with mains
power, a TV receiver and a fringetype antenna. By arrangement,
would-be viewers could meet Arch
there at mutually suitable times and
see for themselves, in a rural family
setting, what was involved in the
then-new and unfamiliar form of
entertainment.
·In due course his eldest brother
George, who was marketing TV
receivers in the Murgon area, commissioned a TV service van with a telescopic antenna system, which could
check signal levels at customers' own
homes. Arch lent a helping hand when
necessary and also helped out with TV
servicing jobs.
He and Desley also helped family
members in the car business, sometimes forming a party to ferry new
vehicles up from Brisbane - a tedious
business for both themselves and other
road users because they were not supposed to push new and 'tight' engines to
beyond40mph(69km/h).
Pre-war, Arch had always been a
'Chev' man, but after the war he settled
for the Chev's big brother - an ex-disposals Pontiac.
This was followed by a new Chevrolet, aftel" which he had to transfer
his affiliation to Holdens. Holdens
were OK, but he couldn't say the
same for their English cousin the
Vauxhall - which, he claimed, used
to pitch and 'bucket' along Australian
country roads.
The Holden 'Brougham' earned high
marks, because he saw it as a scaleddown Chevvy. Jap cars didn't rate, on
principle, and only right at the last did
Arch and Desley settle respectively for a
Datsun and a Toyota!
As the 1970's gave place to the 80's,
Desley sensed that her husband was
feeling his age. They had retired to an
eight-acre property for 'peace and
quiet' but even with a ride-on mower,
Arch could not keep it tidy to his liking.
His beloved lawn bowls slipped from
competitive play to a social game one
day a week. And, for whatever reason,
his sight had deteriorated to the point
where he had no hope of coping with
transistoriserequipment.
Final, fatal blow
Then in early 1986, at age 72, he was
diagnosed as suffering from a melanoma,
possibly from the years he had spent outdoors in Burma - his naturally fair skin
often protected only by a loin cloth.
He entered hospital in April 1986 for
an operation, which appeared to be
successful. But the doctors misread
the signs, compounded by Archie's
own diffidence and what was diagnosed as a harmless residual cyst
proved to be malignant and invaded his
lymph glands. He died in November
1986 at age 73.
I can pay no higher tribute than to
remark that Archie Caswell had been an
associate of the late Dr 'Weary' Dunlop
on the infamous Burma Railway. But
while his contribution may have been
less dramatic, he was certainly made of
similar material! <¢•
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FORUM
Conducted by Jim Rowe
TETIA and qualifications for
service technicians - the debate continues...
Wow - we really seem to have stirred up a metaphorical hornet's nest, with our attempt to discuss
the subject of qualifications for electronics service technicians. The letters and faxes have kept on
arriving, currently still in response to the airing we gave to the topic in the November issue.
I'm sure most readers of this column
are well aware of the background to this
topic by now, but here's a brief recap.
Back in April last year, we published a
notice in the Serviceman column to the
effect that TETIA had decided not to
contribute any more 'Fault of the Month'
items. This prompted a response from
reader Robert Heywood, published in
the July column, whose comments (and
my own accompanying comments) upset
TETIA's Jim Lawler and his colleagues.
I published Jim's response with an apology in the September column, but this
triggered off some further responses,
which were published in the November
column. And these in turn have spawned
responses of their own, some of which I
presented for your interest in the January
issue. (It's all starting to seem a bit like
one of those Russian 'Babushka' dolls,
isn't it? Each one you open up has another one inside it.)
Anyway, that's a precis of the story
so far. Now let's re-enter the fray, with
a letter from - wait for it - Mr
Robert Heywood.
No, it's not the same Robert Heywood who wrote the original letter last
July, but his father Robert Heywood
Senior, who apparently runs a servicing
company called Rutherglen Technical
Services in Rutherglen, Victoria. And
not surprisingly Mr Heywood Snr is
seeking to defend his son, in particular
with regard to some of the criticisms
made by TETIA member Mr A.F. Ransley, in the November column. So in the
interests of fair play, here's Robert Heywood Snr's response:
I fancied hearing a rattling of old
bones when reading my sons letter in
your column. Subsequent issues proved
my clairaudience. His comments not
only bought an argument, but also unwittingly breathed life into what I had
thought to be one very dead dog.
40
ELECTRONICS Australia, February 1995
But the dead can wait. First to Mr
Ransley and his remarks.
His sarcasm is poor argument. I, too,
find it a pity when incompetent people
cause problems. From customers stories
over the past 30 years, I have found most
problems are caused, not by 'qualified
hobbyists', but professional servicemen,
some of them members of TET/A.
Silly remarks about multimeters notwithstanding, I considered my son one of
my better apprentices - and I have
trained many. Unlike myself, he has no
formal qualifications in electronics. But
then, if you subtract my own original
qualifications from the work I now do,
you find we are equally unqualified, in
the same way many of the people in todays service industry are.
(If Mr Ransley has indeed 28 years
experience, then no doubt he learned his
trade on Astor Sis as I did. And he probably did it at the same 'leading Institute
of Technology', whose teaching style
was then aptly fitted to its location between the museum and the brewery.)
Learning process
Electronics is an applied science. How
it is learned is hardly important. Like
most of us, my sons experience in electronics and servicing has already outstripped anything he could have learned
at TAFE. I also suggest that Mr Ransley,
like all others in the service industry,
did, in fact, gain a certain amount of his
early experience through trial and error,
and often at the customer's (or the
bosss) expense. To have 'done it the
hard way in a retailers workshop' and
not admit this fact is rather silly. 'Been
there, done that!'
I am glad he uses quotes over the
word 'Qualified'. For, unlike the science of electronics, servicing is an art.
It can only be learned by experience,
and like other arts, preferably under
guidance. Those who doubt this simply
aren't in the business. How and where
we gain our servicing experience most
likely counts for about half of our subsequent ability. The rest is dependent
upon type and intellect. There is no
doubt that the more than merely competent serviceman is one of the most intelligent and creative of people, and here
lies the irony of his position; one of the
reasons why, when I was my son's age, a
newly formed group was pushing for the
licensing of TV servicemen.
At that time there was a general dissatisfaction with awards. Nothing was
achieved and little has changed. But
those in the service industry at least saw
a possible 'out' in licensing. The notion
was seen for the essentially unreasonable and unethical grab for loot that it
was. It is interesting to note, however,
the evolution of the reasons used to justify the idea - couched, as they always
have been, in the breast beating rhetoric
of 'getting a better deal for the public'
and 'cleaning up the industry'.
In the sixties it was a grab for status
and money, nothing more. At a time
when the electronics tradesman saw his
'unqualified' colleagues in the public
service, banks and retailing receiving
wage increases through seniority alone
and saw his mates in other trades taking
home pay packets he could only dream
of, it was to be expected. His trade was
considered merely an extension of the
metal workers and he was paid a fitters
wage, one of the lowest in industry. Too
highly qualified to be satisfied or even
wanted on the factory floor, he sought
his fortune elsewhere, often in retail
servicing. But the spectre of his lowly
status haunted even the newest and
brightest of workplaces, let alone those
dank lean-tos attached like barnacles to
the rear of electrical retail stores, where
so many of us plied our trade.
Now, at a time when increasing complexity and reducing intrinsic value have
removed all but the experienced diehards and the newly competent from the
industry, the proponents of licensing are
telling us the public need to be protected
from unqualified people? Come on. That
was a fact years ago, when anyone who
had ever built a crystal set reckoned he
could change a few valves and get a
piece of the action.
No, the push for licensing comes down
to the same old things: the prime directive which can be inferred from Ray
Banks' letter (strains of an old Abba
song here, 'Money, money, money... '),
and the desire for self image verification.
This is where the whole shoddy mess
comes to a head; where any mention of
qualifications is like jumping on a bull
ant's nest.
There is no doubt that if the electronics industry had never accepted the silly,
hierarchical qualification structure bequeathed to it by the 'bums on seats'
attitude of our educational institutions,
and if industry had recognised and related the skill of the electronics tradesman to something nearer its proper
level, we wouldn't have the ego problem.
But the real tension lies in the fact that
electronic servicing is a skill, where
competence and knowledge are not reflected by educational qualifications.
Rhetorical or not, Mr Banks' questions
of who should be allowed to fix what
stem from a misguided perception of
technical competence. Either a person
has the experience or he doesn't, and
this has little to do with qualifications.
Sure, I expect a technician to know his
electronics, then with time he will become competent in any area of the trade.
Just as most of us have.
(In this regard it is also interesting to
remember that most cassette, video and
disc player faults are mechanical. Include in this the dj's, blatantly obvious
bum outs and tube faults in TV's and it
doesn't leave much for our hard won
knowledge of the latest electronics.)
But you cannot license for competence any more than you can discern its
existence from the results of a memory
test. (What waveform do you expect
here... ? Indeed!)
It is in the nature of the serviceman to
look down upon others in the industry. If
you don't have solder burns in your trousers you don't count for much. Aform of
intellectual chauvinism; and not surprising. Few know more in their particular
field than the highly competent electronics serviceman.
But to ask for industry control is
wrong. It confuses a quality with a
measurable quantity, and asserts the
existence of a need that exists only in
the minds of those like Mr Banks.
Unlike him, I have never found a customer 'unwilling to pay a fair price for
work done'. The emphasis here being
upon 'fair'. I believe my notions of
fairness might differ, however, from
those of TETIA.
Licensing would neither rid this industry of incompetents nor save customers
from the rip-offs that abound in it. The
operation of the free market proves just
as effective. Just as in Roman times
when it was said 'a good wine needs no
bush', if a person offers quality at a fair
price neither remoteness nor inaccessibility will stop people from beating a
path to his door.
Finally, I suggest Mr Banks' fears of
'being lumbered with some unworkable
system by bureaucrats' are groundless.
They are based on an unreal perception
of the importance of the service industry,
and the unjustifiable notion that the aims
ofpolitically motivated groups necessarily reflect the opinions, and indeed, the
needs of the majority.
His/ears should be laid to rest, along
with the dead dog he and his cronies in
ELECTRONICS Australia, February 1995
41
FORUM
TETIA have been flogging since the
late sixties.
As for the withdrawal of the 'Fault of
the Month', much could be said regarding
the psychology of groups and their need
for secrets, but I will not bother here. I
suggest it was of interest only to those in
the trade anyway and, if the truth is
known, of little real value. It's loss simply
means you now have more space for
something of greater general interest.
Thanks for your contribution to the
debate, Mr Heywood Snr. I for one
found your comments both interesting
and thought provoking, and I'm sure
others will too. Your point about the
rapid changes in technology tending to
make most of us equally 'unqualified',
in time, is a very valid one - and one
that applies to pretty well all of us in
electronics, not just service technicians.
I also liked your point about a good
service technician being very intelligent
and creative, too. That's something I've
always believed myself, and to me it explains why our Serviceman column has
always been so popular - even with
people who have very little technical
knowledge themselves, and have no intention of ever trying to service equipment. Quite a few such people have told
me, over the years, that they really enjoy
reading Serviceman because often the
stories are like 'who dunnit' mysteries;
you keep reading to find out how the
Serviceman finally tracked down the
cause of the trouble!
There's also a ring of truth in Mr Heywood's suggestion that virtually everyone in the servicing industry, including
Mr Ransley, will have gained some of
their early experience through 'trial and
error', and often at either the customer's
or boss's expense. Trial and error surely
forms an important part of the 'experience' that we all get, in just about any
field of activity - a fact recognised in
the old saying 'Show me someone who
has never made a mistake, and I'll show
you someone who has never done anything'. To suggest that 'qualified' technicians are somehow immune from this is
indeed rather silly, as Mr Heywood Snr
points out.
What is 'qualified'?
Anyway, let's move on to our next letter, which comes from Mr Bryan de Pree
of Beaufort in Victoria. Mr de Pree takes
up the matter of technical qualifications
and their value, and gives it an interesting slant from his own experience:
I have enjoyed your magazine since
42
ELECTRONICS Australia, February 1995
I969, but this is the first time I've put
pen to paper to you, although I have
contributed to Peter Phillips' articles.
The intense letter in 'Forum' II/94 by
a service technician regarding professional qualifications brought back some
bitter-sweet memories. I am an electronics engineer, graduated in I 964 from the
Polytechnic University in Arnhem, Holland. Despite assurances from the immigration officials, when I arrived in
Australia in I969 my qualifications were
not recognised by the Australasian Society of Engineers. I was not even allowed
to sit for an exam, to prove that I would
be up to standard!
Some of the compulsory subjects in my
secondary education (during all the five
years) included: mathematics, physics,
chemistry, biology, accountancy, French,
German, and English; there were I6 in
all. Although it is difficult to list subjects
for a technical education, it included
mathematics to the highest level, error
theory, technical English and German as
well. Both education levels require approximately 36 hours attendance per
week; Saturday is a normal study day
over there.
Honours graduate...
Although I graduated with honours
and had worked as a development engineer at the Aeronautics and Space
Laboratory in Amsterdam, and was a
member of the first computer design
team (all I6 of us) at Philips Computer
Industries for three years before I entered this country, I was not given the
opportunity to prove myself before this
inward looking association.
After doing some development work
on UHF transmitters for the then Commonwealth Development Laboratories,
I got back into the computer field, this
time as a service engineer. This was to
me a completely different life, from being creative to fixing someone else's
problems. Being overqualified, I progressed rather rapidly and was one of
the country's highest paid computer engineers in I97I.
When I was state manager for an
American computer company in I 983, I
employed a man as an engineer who was
IO years my senior. This in itself would
be politically incorrect nowadays, when
age seems to be so important. But more
is to come. He had no secondary or tertiary education and had run, as he called
it, a 'lollyshop'for the past IB years. The
reason I took him on was. that I found
him to be a most intelligent and resourceful person. He had been the 'electric man' in a circus, and made shopping
trolleys from junk collected on the tip in
the depression years. He had his pilot
licence and fixed the 'tug' of the glider
club of which he was a member.
What was even more surprising was
the fact that he had taught himself electronics (your magazine was partly to
blame!), and designed the very first cell
call system here. He did not have the
money and time to patent the design, but
nevertheless sold about 200 systems before the big brand items hit the market.
Give him anything that has a transistor
in ·it and with the schematic in hand,
he'll fix it.
To cut a long story short; of the IO
engineers I employed with that company,
all of them top people, he was by far the
best overall. I doubt if he would be eligible to be a member of TETIA, even
though he would beat most of their members hands down in technical skills. Now
he is unemployed, as a result of a company demise, and being in his early 60's
has little chance of obtaining a job. In
the age where the emperor's magic coat
seems to be discrimination, where is the
Australian fair go for those with no
piece ofpaper and no youth any more?
If we are going to be a smart country,
does that not include taking stock of our
talents other than looking at recognised
and accredited education? To be honest, in my experience over the years in
the electronics industry, I have found
those that started out as amateurs in
general to be better suitable for the job
than others.
At the moment I have a running discussion with a 'properly trained' engineer who maintains that the different
lengths of the positive and negative
leads from a bank of batteries to an inverter effect the operation of the inverter
in a major way. Sounds like the infamous
speaker lead saga?
To be an academic and never having
had dirty hands can lead one into fairy
land. I sometimes wonder if we would
be better off to send all the lecturers
home and let the kids do their own education; perhaps we would end up with
better professionals.
The attraction of magazines like 'Electronics Australia' is partly because people contribute who are electronic men
down to their bones, with or without papers. It is good to have a magazine without the hype of many of the
'professional' magazines.
Thank you for your comments too, Mr
de Pree, and again they're both interesting and thought provoking. You've certainly had not only personal experience
of being 'tripped up' by lack of recognised qualifications, but also experience
with a service engineer who excelled de-
spite lacking such qualifications. I guess
quite a few of us have experienced either
one or the other of these, but not both.
Presumably you have even more reason
than most to regard formal qualifications
per se with a somewhat cynical eye ...
At the very least, practical experience
and old-fashioned enthusiasm need to be
taken into account as well as qualifications, as you've pointed out. And I quite
agree that often people who start off as
'amateurs' and keen enthusiasts can make
far more capable 'professionals' than
those who don't. We've certainly found
that on the magazine itself, for example.
I doubt whether it's logical to conclude that we should close down all of
our schools, TAFE colleges and universities, of course. Presumably you made
this suggestion more in jest, as a way of
emphasising the point. However I'm
sure you're right in saying that if we
really do want Australia to be a 'smart'
country, we should be more flexible and
place less emphasis on (blind faith in?)
sheer formal qualifications.
Storm in a teacup?
Moving on again, our next contribution came in the form of a fax from
Frank Russell, of Wendouree in Victoria
(we've really got the Victorians going
this, time, haven't we?). Mr Russell is
also picking up on the matter of TETIA' s
decision to discontinue 'Fault of the
Month', etc., but his approach is a little
different again, as you'll see:
I have just read with considerable
amusement the series of letters in the
'Forum' column of the November issue,
on the subject of TETIA $ attitudes to
service techs qualifications.
My amusement comes not so much
from the insular attitude of the co"espondents concerned, but rather at the
ridiculous storm in a teacup that has
arisen over the discontinuation of the
TEI'IA fault reports. The joke is that almost without exception, the faults that
were published either related to very
early models, of a type most unlikely to
be presented in an average workshop for
service at todays rates, and thus pretty
much in the domain of the 'backyarder'
anyway, and/or they were faults so routine and well known that few if any experienced technicians would not have been
well aware of them!
As a matter of interest, my own formal
training is in Electronic Engineering,
with some 20 years of subsequent experience in both consumer and industrial
diagnostic electronics maintenance. I
am cu"ently employed by the University
at which I trained, as a senior Technical
Officer (Electronics).
Ironically though, within the guidelines previously suggested by Mr Lawler,
like you, I am unqualified! I have however, prospered in the industry at many
levels, without ever needing to join
TEI'IA or any other so-called industry
body. If they like to keep a closed club,
good on them.
Perhaps though, its time for TETIA to
join the real world, and realise that if
they are truly to improve the image and
standard of the industry, a much better
approach than their apparent position of
blind criticism is to invite the supposed
'cowboys' to join their ranks, where they
can at least be evaluated by their peers,
and be encouraged to train and develop
'acceptable' qualifications. I believe this
would be more effective than throwing
stones from a great distance, with poor
aim and little real knowledge of the aptitude and talents of their objects of scorn.
My personal experience teaches me
that TETIA still has a long way to go in
cleaning up its own ranks, before they
can afford to become overly critical of
the performance ofothers.
Thanks for your comments too, Mr
Russell. I imagine that your comments
won't win you too many friends from
within TETIA, but you're entitled to
your opinions and some of the comments made on behalf of TETIA have
been equally strong.
In fairness, I think it's a bit rough to
suggest that all of the cases that were
discussed in Fault of the Month concerned very early models of interest only
to 'backyarders', or routine faults that
would be well known to anyone with experience. Some of them may have been,
but I believe quite a few of them would
have been of interest to independent service techs and those in isolated areas, as
well as some general readers trying to fix
their own equipment.
I have to say that my own reaction to
this whole business of TETIA dropping
its support for Fault of the Month is
more one of sorrow, rather than amusement. Not so much for the loss of
'FOTM' itself, but rather for what it
seems to reveal about current attitudes in
at least one area of electronics.
To me, one of the really good things
about electronics in the past - as both a
hobby and an industry - has been its
spirit of cameraderie. Most of the people
in electronics have been really involved
in and enthusiastic about what they were
doing, and were happy to share information and help each other increase their
knowledge and skills - regardless of
whether they were 'amateurs' or 'professionals', at one level or another. TETIA's
decision to drop 'FOTM', and the rea-
sons given for this decision, suggest to
me that this spirit of friendly cooperation
is now starting to wane - being replaced, it appears, with a somewhat
more selfish 'Why should I share this
knowledge with you?' attitude...
Perhaps this kind of change is inevitable, and simply another reflection of the
way our society is becoming more competitive and aggressive. However I do
find the change unfortunate.
I know previous Editors of EA took
great pride in the magazine being a medium for allowing people at all levels in
electronics to communicate with and
help each other, and that's my continuing goal too. Many people have told me
that's one of the reasons why they keep
buying and reading the magazine, because despite all of the stresses associated with modern life, economic
pressures and galloping technology, we
still strive to foster this friendly spirit of
mutual help and cooperation.
Call me old fashioned and naive, but
the prospect of electronics becoming just
another 'beggar thy neighbour before he
beggars you' business doesn't give me
much joy at all.
And with those few words, I think we
might give this topic a rest - for a while
at least. Don't you think? •:•
Do you enjoy reading about
vintage radioJ
If so, you'll enjoy Peter
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Discovering
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We've collected together 34 of
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It covers the development of
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the evolution of radio receiver and
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Available from your newsagent or
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$4.95, plus $2 p&p when ordered
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ELECTRONICS Australia, February 1995
43
THE SERVICEMAN
@@
..............-------------------------------------------------·CJ
••• @@
The Sanyo colour TV set
that I almost put an axe through!
This month my main story is from my own bench, and it concerns my long and incredibly frustrating
battle with a Sanyo CTP6631 which seemed determined to send me either broke or insane. There's
also a brief but intriguing story of a problem with noisy telephone lines, which turned out to have a
surprising cause.
As I mentioned a couple of months
ago, A.L. of Beverly Hills in NSW has
given me a large collection of stories to
chose from. I think the reward for such
enthusiasm should be pride of place at
the head of this month's column.
I don't know much about A.L.'s
background, but from the subjects
of his stories I would say that he was
once a telephone engineer, now turned
security system specialist. To show why
I suspect this, we'll open this month
with a yarn he calls 'The Slightly Pink
Noise Problem' ...
During the construction of a motorway, it was necessary to reroute a number of telephone circuits and as a
temporary measure an open wire line
was leased from the local railway
authority. This line ran parallel to an
electrified suburban rail service for
about JOkm.
We connected each end of this line
to two 12-channel carrier terminal
bays, to provide 24 bi-directional
Light
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9
Peter C. Lacey Services Pty. Ltd.
80 Dandenong Rd. FRANKSTON 3199
Tel:(03) 763 2388 Fax:(03) 763 5767 ACN006893438
44
ELECTRONICS Australia, February 1995
telephone channels. We aligned the system and early on a Sunday morning
crosspatched the circuits affected by the
motorway construction. These circuits
all tested OK, but by midday on Monday we had received a number of complaints of random noise on these lines.
At the distant end the input of one of
the noisy channels was terminated
and a psophometer (a noise
equivalent power meter) was connected to the near end of that channel.
The incidence of the noise at first appeared to be quite random, but as the
day progressed and we accumulated
more data a definite pattern emerged.
The noise bursts occurred in groups
of four or eight, over a period of
JO minutes, with a 20-minute pause
when there was no noise. Suddenly
the penny dropped! What we were
recording was an analogy of the
train schedules.
We obtained a timetable, from a staff
member who travelled on that line and
correlating the departure times for the
upline and downline we found an excellent agreement.
To confirm this, we equipped a technician with a stop-watch and sent him
on a train trip. The correlation of his
results was perfect. The noise only appeared when the train was departing a
station and the noise burst length corresponded to the period that the traction motors were series connected, as
the train accelerated.
As this was only a temporary arrangement and there were no data circuits
on the system, we decided to live with
the problem until the permanent
rerouting of the telephone circuits could
be completed.
Well, how about that? I suppose it
took a bit of lateral thinking to link the
noise with local trains, but I imagine
that those telephone circuits must have
been pretty sensitive to be affected in
that way.
I once had a workshop close by a
Melbourne suburban railway line, and I
can't recall ever noticing interference
from the trains. However, that was in
the days of five-valve mantel radios,
and they weren't all that sensitive. Perhaps high gain audio circuits might
have been different. Anyway, thanks
A.L. for that story. We'll use more of
your contributions in coming months.
Now, for a tale of woe from my
own workshop.
Satanic Sanyo
Have you ever had one of those jobs
where nothing seems to go right? You
stagger from disaster to chaos and
finish up hoping the workshop will burn
down overnight! I've just completed
one such job, and I can honestly say I
have NEVER been so pleased to see a
television set leave my premises.
In fact, I was so glad to see it go that
I declined to charge anything for my
labour - just the cost of the handful of
parts needed to make the beast workable again. This is how it all happened...
It was a Sanyo 20" model CTP6631,
fitted with an 80-P chassis and the complaint was that it just wouldn't work.
There was no sound and no picture.
Initially, that was no trouble. The
line output transistor, a 2SD869,
was almost shorted. That sounds a
bit odd, but it is a true description of the
state of the transistor: it was showing
about 100 ohms between each terminal.
Usually, line transistors go dead short
when they fail, or show 1000 ohms or
so if they are just leaky. This one was
halfway between the two states. I don't
know what its condition signifies, but it
means something as you will find later
in this story.
There is no universal cause of line
output transistor failure, but one common cause is a bad drive waveform.
This results in slow switching and excess dissipation, during the transition
from 'on' to 'off' or vice versa.
Again, there is no usual cause for this
trouble, but one thing I have found is a
dried-out bypass capacitor on the supply side of the line driver transformer.
This is often a low value, high voltage
electro - and we all know what that
means, don't we?
In this case the relevant cap is
C451, a 4.7uF 160VW unit and I
pulled it out for a close examination.
It was showing no leakage, but its
capacity had fallen to 4.0uF. This is
within the specified tolerance of most
electrolytics, but it is not normal to
find one lower than its rating. Most
are on the high side, so this one could
have been on its way out.
I changed it for another capacitor,
rated at 4.7uF but actually reading
5.7uF, which should eliminate any possibility of failure on that score for some
time to come. I took the opportunity to
check for dry joints around the driver
and output stages, but could find nothing untoward.
It remained to be seen what would
happen when I switched on, but this
point in every job is a bit of a risk. No
matter how carefully you check component integrity, there is always the
chance that you've missed something
and the job will blow up in your face metaphorically speaking, that is.
This time, it was an anticlimax. Nothing unusual happened. The set came on
with a good picture and normal sound,
and as a final check, I measured the HT
rail to see that there was nothing wrong
in that department. So after a few hours
of soak testing, I called the owner and
invited him to take his set home. And
that was where the story sat, for all of
two weeks.
Then the customer was on the phone
to tell me that the set had failed again,
in apparently the same way as last time.
Like most owners, when their set won't
start up, he wondered if it might be the
power switch and would it be
worthwhile fitting a new one. I reassured him on that score, saying that I
hoped it was the switch and that I
would gladly fit a new one, but only if
that really was the trouble. Unfortunately, it sounded to me like a repeat of the
last fault.
Same problem!
When he brought the set back, I
found that it really was a re-run of the
old programme. The new transistor was
'nearly' shorted, just as the last one had
been. Now, if it had failed in any other
way, I would have been happy to accept
that I was facing a new problem. But
this one was so nearly the same as last
time that I began to get that sinking
feeling. I sensed this was going to be a
tough one, and I wasn't wrong!
I was still thinking along the lines of
bad line drive, so after fitting a new
output transistor, I left the collector
open and gingerly switched on. This
way, I was able to look at the line drive
on the base of the transistor, to see if I
could find any clues to the malfunction.
With the collector disconnected, the
base waveform is not strictly correct but
I've found it to be a good enough guide
in these difficult circumstances. However I could find nothing wrong, so I
had to reconnect the collector and try
again. This time I attempted to protect
the transistor by putting a 60W lamp in
series with the collector. This limits the
current that can flow in the transistor, in
the event of a fault that might cause a
short circuit.
Now the base waveform was perfect,
as was the collector waveform - although the latter was much reduced in
amplitude because of the load imposed
by the lamp. I checked everything I
could think of, including the B+ rail,
and found nothing wrong. The only
thing left to do was to remove the lamp
and see what happened.
Well, what happened was this. As
soon as I switched on, there was a loud
squeal from somewhere inside the set,
then nothing. And the new transistor
was now half shorted, just like the
others had been.
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Some of our Serviceman's problems with the Sanyo CTP6631 originated in the switching power supply section, shown
here. The regulation of the supply was intermittent, which had disastrous effects elsewhere in the set.
ELECTRONICS Australia, February 1995
45
SERVICEMAN
This was getting expensive! There
was nothing for it but to replace the
transistor, again, and refit the protection
lamp. This time the nature of the fault,
though not yet its cause, was quite obvious. The B+ rail was now reading
250V instead of llOV! No wonder the
transistor died. But I wondered about
the cause of death. Was it consistent
- did the others die for the same
reason? I still had to find out.
The power supply in this chassis is
relatively simple. It comprises a self-oscillating chopper based on the converter transformer T301 and the
chopper transistor Q304. As configured
here, the chopper will deliver an output
on the secondary side of the transformer at around 250 volts, as I had
found to my disquiet.
The regulation circuit acts by
reducing the chopper 'on' time by varying the voltage on capacitor C314. This
voltage is developed across the Error
Drive transistors Q302 and Q303, and is
controlled by the Error Detector Q301.
The only reference in the whole circuit
is that provided by zener diode D305.
(The other zener, D306, appears to
be an overload protector, since it is a
9V device but only ever has 6.4V on its
cathode in normal service.)
So somewhere in this small and relatively simple circuit, I was going to find
a faulty component. I went over that
circuit three times and found nothing.
All the resistors were correct, the
capacitors were all of approximately
I•
AUOIOAMP.
IC1111 LA4220
I
correct value, the transistors showed
normal gain and no leakage, and the
diodes also showed no leakage. So what
could be wrong?
To make matters even worse,
when I next switched the set on, the
power supply was delivering its correct voltage!
But you have to get lucky sometimes,
and this time I got a little bit lucky.
Even as I watched, the supply rail shot
up to 250V again, which told me that I
was now chasing a component that was
intermittent. However, before I could
hit the off button, a puff of smoke escaped from the audio output chip which implied that my 'little bit lucky'
patch was well and truly over...
In utter disgust, I pushed the set into a
corner and went on with other work. I
felt that a week away from the monster
might let me attack it later in a better
frame of mind.
Before I got back onto the job, I had
reason to contact a colleague who has
wider experience with Sanyo sets than I
do. He is the local service agent for the
brand, and has come across almost
every problem that it can offer. After we
had discussed the matter that had taken
me to his workshop, I broached the subject of the runaway power supply in the
80-P chassis.
He dido 't hesitate before nominating
C314, the 47uF electro that couples the
regulating voltage into the base of the
chopper transistor. It seems that this
capacitor has a history of drying out or
0.1'
46
ELECTRONICS Australia, February 1995
No contrast?
As the tube warmed up, I could see a
picture of sorts on the screen. There
was lots of colour and the screen was
bright enough, but the picture was very
pale, as though the contrast was turned
right down. When I turned the colour
off, all that remained was a vague outline of the subject on a screen that was
a little brighter than normal.
When I turned the set off channel, the
screen filled with pale, weak snow.
That, and the presence of colour on
channel, suggested that the front end of
the set, from the tuner to the first video
amplifier, was all working normally.
The rest of the video processing talces
place in IC201, a 30-pin M51394P and
SF AMP. DEMOO.
IC151 LA1311
R>M
C117
going open, and this is known to cause
elevated output from the power supply.
When I got back to my own
workshop, I lost no time in removing
the capacitor for a thorough check. I
tested it for leakage and it got a perfect
bill of health. But when I tested its
capacity, it began by showing the correct 47uF, but then dropped suddenly to
zero, and just as suddenly returned to
correct value. So that was the trouble an intermittent electro!
I replace~ the capacitor and checked
the output rail. It was a bit low, but
responded to adjustment. And as far as I
can tell, the power supply has performed perfectly ever since. However,
that wasn't the end of the story; not by
a long way.
This section of the Sanyo
CTP6631 schematic
shows the sound
clrcuHry and also the
contrast control - both
areas that gave our
Serviceman further
trouble.
my CRO soon showed me that healthy
video was entering that chip on pin 1.
The first stage is a simple buffer, and I
could see that it was worl<lng normally
because of the good video emerging on
pin 3. This video then goes two ways
- to the chroma input on pin 29 and
via the video delay line to the
luminance input on pin 11.
However, I could find very little
video on pin 11, or indeed anywhere
along the chain of components around
the delay line. The video amplitude
dropped dramatically across R2 l l,
then changed very little up to pin
11. I couldn't make out exactly what
was going on, but it did look suspiciously as though the video chip might
have been damaged.
Next, I checked all of the voltages
around the chip. They were all about
10% low, with the exception of pin 12
which should have been 6.2V but was
in fact down to 4V. Now this pin is the
input from the contrast control, which is
a simple voltage divider from the 12V
rail - although it does have a high impedance connection to the llOV rail.
The low voltage made me feel that an
investigation around this area might be
in order.
Then I noticed the sub-contrast control (VR210) and I wondered what
would happen if I adjusted this item.
First, I made a note of the exact position it was set on, then I turned it first
one way then the other. The first movement removed all traces of the picture,
but the second improved the picture
quite markedly.
This response suggested that I might
have a contrast control problem, so I
went to the front panel and tested the
pot mounted under the tuner. It was
supposed to be 30k ohms, but as far as I
could tell it was around 300k. It was
clearly worth a better look, so I
removed the control panel and took the
pot off the board.
Now the trouble was readily apparent, since the pot was open circuited from end to end, but OK from
one end to the centre terminal. When I
opened it up and looked at the track
with a x I 0 magnifying glass, I could
see where the 'hot' end of the track
had been burned away from the terminal. This end was normally supplied with 12V from the 12V rail,
which in turn is derived from the 15V
rail. If the voltage had gone high
enough to bum out the contrast control, one would think it should have
done very nasty things to all the
chips on the board. But that seems not
to be the case ...
I was able to effect a complete cure,
without even having to change the contrast pot. I merely shifted the leads
across one position, making the centre
terminal the 12V input and the other
end terminal the lead to the video chip
input. (I don't often get that lucky!)
After I reset the sub-contrast control, the set delivered a first class picture, proving that nothing else in the
picture chain was damaged. That only
left the audio chip to be replaced, and
that proved far less easy than it
should have been.
The audio is processed in two chips,
ICI51 and IC161. The first, an
LA1365 is the sound IF amplifier and
demodulator. The second is an LA4220
audio drive and power amp. It was the
latter chip that had 'lost its smoke'.
I had an LA4220 in my kit but it
wasn't a new one. It had been taken
from a working set that was junked
because of a bad tube. I had no
reason to think that the chip was faulty,
but it was since after fitting it into the
set, there was no sound and no voltages
on any of the pins, except on pin 3, the
18V supply rail.
A close examination of the circuit
showed that all the given voltages have
to be derived from within the chip,
since there are no connections to any
other part of the circuit. This killed any
hope that the fault might lie elsewhere
on the board, and confirmed that my
spare chip was faulty.
Finally, I used a small test amplifier
to check that the input, on pin 10, was
receiving a normal audio signal. Repairing the output stage would have been
pointless if there was no audio to
amplify. Fortunately, there was a norm al signal coming from the
demodulator chip, so the rest of the job
looked as though it would be quite
straightforward.
So it was back to my Sanyo Service
Centre friend, to see if he could lend me
an LA4220 until I could get a replacement. By this time I was desperate to
finish the job and get the set out of my
workshop. I didn't want to wait while I
got a new chip from a distant supplier...
My friend's response to my request
was a laconic "Ha! Ha!", and then "If
you find any, get a dozen for me!"
When pressed for an explanation, he
told me that the chip had been discontinued some years ago, and was no
longer available. There was a substitute
listed, but it required a number of
modifications to the circuit before it
would work properly.
That news was the last thing I
needed. I had already done more to
this set than to just about any other I
had ever worked on, and now I was
going to have to rearrange the audio
channel. If there'd been an axe handy, I
might have used it to fix that set once
and for all!
Sheet of mods ...
Anyway, in due course the new chip
arrived. It was an LA4265, and came
complete with an instruction sheet
detailing the procedures needed to complete the modification.
As I read through the instruction .
sheet, I began to think that this was
more than just a modification. It was
more like a total reconstruction!
First, C164, C165 and Rl62 are to
be deleted. Then a 3.3-ohm resistor is
to be added between C167 and ground,
after cutting the track that links the
capacitor to ground. Then R156 has to
be changed from lOk to 56k, R160 from
lOk to 3.3k, Rl61 from lOk to 270
ohms, C162 from 33uF to lOOuF, C168
from 4.7uF to lOOuF, C167 from 0.15
to 0.1 and C161 has to be shorted out.
But that's not all...
The circuit track between pin
8 of IC161 and the positive side of
Cl61 has to be cut, and a short circuit
fitted between pins 8 and 10 of the IC.
And of course, not to forget to change
the IC itself!
After all this was finished, we
once more had a fully functional
television and I called the owner to
come and take the accursed thing away.
I had lost count of the time I had spent
labouring over this set, and I couldn't
have charged for more than a fraction
of what it was worth. Instead, I billed
the customer for the parts used and
asked him to never, ever bring the thing
back to me.
And to· think that the whole sorry
saga came about because of an intermittent open circuit in a 47uF electrolytic
capacitor in the power supply!
Incidentally, before I leave this story,
the mod sheet that came with the substitute audio amp chip listed all the
Sanyo models affected by the changes.
There are no less than 123 model
numbers in the list. Many of these are
overseas models, but a majority could
well turn up in this country. So
whatever you do, when you are servicing one of these Sanyo sets, be
very careful not to damage the LA4220
- replacing it will be a long and involved exercise!
That's all for this month. I'll have
more interesting servicing stories for
you next time. •>
ELECTRONICS Australia, February 1995
47
Kawai's external MIDI synthesisers take your PC
OUT BEYOND
THE SOUND CARDS!
PC sound cards are fine for adding sound to games, and for your first experiments with MIDI music
making. But for those who want to go further, 'outboard' synthesisers like Kawai's GMega and
GMega LX provide an excellent way to boost your PC's MIDI synthesiser facilities with a minimum of
hassle. The Kawai Datacat can also provide your PC with a compact, economical and very easy to
use MIDI keyboard controller.
by JIM ROWE
Although many musicians have been
using the MIDI (Musical Instrument
Digital Interface) system for a long time,
many of us have only become familiar
with it in the last couple of years, with
the welcome appearance of PC sound
cards providing inbuilt MIDI interfaces,
and also low-cost MIDI keyboards. And
these new 'consumer level MIDI'
products are great as far as they go, allowing you to get a good insight into the
potential of a PC-based MIDI system for
all kinds of experimenting with music.
But although just about any PC sound
card gives you enough facilities for a
good 'introduction' to computer-based
music making, many of them turn out to
be rather limited if you want to 'go further into it'. Most of them provide at
least a basic MIDI interface and a digital
audio recording and playback facility,
but many of the cheaper cards have a
fairly modest inbuilt music synthesiser.
These may be fine for producing the
sounds and music for games, but can
prove very frustrating when you try any
48
ELECTRONICS Australia, February 1995
'serious' experimenting - or even to
produce music which sounds as if it's
being played on recognisable instruments.
Fairly obviously, one solution is to
replace your simple sound card with
one of the more elaborate models,
with a more powerful and flexible
'wavetable' type synthesiser. But this
approach can have its own pitfalls;
many of these fancier cards are considerably more complicated to install in
your PC, occupying multiple 1/0 addresses and often requiring more than one of
the PC's IRQ and DMA channels. In
some cases, it can be very difficult if not
impossible to get them going properly,
without causing mysterious 'crashes'
and other system malfunctions.
A simpler and in many ways more
elegant approach is to keep your existing simple sound card, and use its MIDI
interface as a 'doorway' out to a more
powerful external MIDI synthesiser
module. There's a growing range of
these 'orchestras in a box', and quite a
few of them not only provide more
powerful facilities than all but the fanciest sound cards. They're also quite
comparable in price.
With this approach you still have your
original sound card's synthesiser available for games, etc., and you also avoid
the complications of installing a more
complex sound carcl. At the same time,
you gain all of the benefits of a more
powerful synthesiser...
Japan's Kawai Musical Instrument
Company has been making high quality
traditional acoustic musical instruments
such as pianos for many years, and has
also earned quite a reputation for its
electronic instruments. Recently it expanded its range of MIDI-compatible
products, first with the GMega synthesiser module and then with the
GMega LX module and the Datacat keyboard controller. As these products are
good examples of the kinds of
'outboard' MIDI units that can be used
to expand a PC-based music system, we
thought you might be interested to learn
more about them and of our experiences
in trying them out with a typical computer system.
TheGMega LX
Kawai 's GMega LX, also known as
the XC-3, is an enhanced General MIDI
sound module which in many ways represents the 'next step up' from most PC
sound card synthesisers. Although quite
compact - it measures only 219 x 203
x 46mm, and weighs 0.9kg - it
provides the same high quality 16-bit
digital wavetable synthesiser 'engine' as
Kawai's popular KC20 keyboard synthesiser, with a total of 160 different instrument sounds or 'voices', and seven
different 'drum kits'. Of the 160 voices,
the first 128 conform to the now standardised General MIDI (GM) specification, while the remaining 32 form a
second bank of 'extras' and alternatives.
The GMega LX provides a full set of
16 General MIDI instrument channels,
so you can program it to play up to 15
different instruments plus a drum/percussion kit, at the same time. It also
provides 28-note polyphony - i.e., it
can play up to 28 different notes at once,
20 on the instrument channels and the
remaining eight on the drum channel.
A very worthwhile feature of the LX
is built-in digital reverberation, which
can be set up to simulate various kinds
of acoustic environment by means of
MIDI SysEx (system exclusive) commands. You have a choice of six different reverb types, plus control over
reverb time, pre-delay time, and two
'
selectable depth levels.
Of course there's also the ability to
adjust overall pitch ( +/-50 cents), the
tuning of individual channel sections
(+/-64 cents), transpose the key of individual sections (+/-24 semitones), adjust the level and stereo pan position for
each channel, and so on. In short, the
LX definitely qualifies as an 'enhanced
GM' synthesiser rather than a 'basic
GM' type.
A very interesting added feature is that
along with the standard MIDI IN and
OUT (THRU) ports, it also provides a
'computer type' serial port. This means
that you don't even need a sound card or
other MIDI port on your computer, to
use it. You can drive it directly from a
standard RS-232C serial port on an
IBM-compatible PC, a Macintosh serial
port, or the serial port on an NEC
PC9800 machine.
The LX's extra serial port uses an
eight-pin 'mini DIN' connector as used
on the Apple Macintosh, with matching
cables. It's on the rear of the case along
with the standard 5-pin MIDI connectors, and alongside there's a slide switch
which lets you select either the MIDI
port (M) or the serial port as configured
for either Apple Macs (A), IBM-compatibles (I) or NECs (N). Very flexible!
By the way, the LX also includes
three inbuilt 'demo' tunes in ROM, for
system testing and level checks, etc. It's
powered from a 12V DC plug pack
(supplied), and provides an audio output
for stereo headphones as well as linelevel stereo outputs.
The RRP of this very impressive enhanced MIDI synthesiser is $699. Available with it for an additional $100 is a
matching software package with serial
port MIDI drivers, an interactive music
performance package called Instant
Pleasure, and either of two MIDI sequencer programs: Powertracks Pro for
IBM-compatible computers, or GMS
General MIDI Sequencer for the Macin,tosh.
TheGMega
Next step up from the GMega LX is
the GMega synthesiser module, which
was Kawai's first General MIDI unit.
Although the names may be similar, the
GMega synthesiser goes a lot further
than its newer 'little brother' and is more
suitable for those who want to venture
more deeply into MIDI music m.aking.
For a start, the GMega has no
fewer than 256 inbuilt voices, organised in two separate tone banks:
a 128-voice General MIDI bank and a
second 'SP' bank of 128 further voices
offering many different alternative instrument 'flavours' (and compatible
with the Computer Music System). If
·that were not enough, it also provides a
total of 256 different drum, percussion
and sound effects sounds. In all, the
digital infonnation for this total of 512
stored voices takes up 48 megabits of internal ROM ...
But the GMega isn't just a 'bigger orchestra in a box'. In addition, and unlike
its little brother (and also most sound
cards), it has full facilities for the user to
create their own fully programmable
voices. And these 'user programmed'
voices can be stored in a third tone bank
(this time in RAM rather than ROM),
which has space for up to 128 instrument voices and a further 128 drum/percussion sounds.
The parameters for these userprogrammable voices can all be edited
via the GMega's seven front-panel controls and two-line backlit LCD screen.
(They can also be edited on a computer
Kawal's GMega synthesiser module, which provides an impressive 256 In-built instrument voices plus the ability to
program another 128 of your own. It offers 32 note polyphony and full General MIDI compatibility. Opposite: The Glllega
LX synthesiser module, which provides 160 Instrument voices and seven drum kits.
ELECTRONICS Australia, February 1995
49
OUT BEYOND THE SOUND CARDS
1
Compact and attractively priced, the Datacat keyboard controller can generate control codes for any of the 128 notes In
the MIDI pitch span, as well as many other control codes. It includes a dedicated 'pitch bend' controller wheel, and another
wheel which may be assigned to a wide range of other parameters.
and downloaded into the GMega via
SysEx commands, although more about
this later.) There are over 30 programmable parameters per main instrument
voice, controlling either the DCO (digitally controlled oscillator), DCF (digitally controlled filter) or DCA (digitally
controlled amplifier) sections of each
synthesiser channel. Similarly drum
channel editing involves programming
of some 23 different parameters.
The GMega uses Kawai's 'Digital
Multi Spectrum II' synthesiser engine,
which uses 18-bit DACs to replay the
stored 16-bit waveform data. There
are a total of 32 separate synthesiser
channels, each of which can be
programmed to receive on any of 32
MIDI channels - split between two
separate MIDI input ports 'A' and 'B'.
So in effect, the GMega behaves like
two separate 16-channel synthesisers
in tandem, although they share its
32-note polyphony. Each of the 32
channels has its own programmable
level and reverb depth, and the GMega
also offers a choice of 55 different
tuning temperament scales (Equal, Mersenne Pure, Pythagorean, etc.) - with
the ability to program a different one
into each of the 32 channels, if you
wish(!). This gives the ability to produce
'thick' and complex orchestral textures,
all from a single GMega.
Like the LX model, the GMega
provides a standard serial data interface
as well as the MIDI inputs and outputs.
However in this case the serial port is
only compatible with the Apple Macintosh, so owners of IBM compatibles will
still need their sound card's MIDI port.
Needless to say the GMega offers all
of the reverb options provided on the
LX, as well.
Physically the GMega unit is almost
the same size as its little brother,
50
ELECTRONICS Australia, February 1995
measuring 219 x 189 x 44mm and
weighing only a little more - 1.5kg. It
too runs from a plug-pack supply, which
in this case is a lOV DC unit.
As you can see, the GMega unit
offers considerably more than its
smaller brother. Not surprisingly it's a
little more expensive, with an RRP of
$1199 - which still seems very
reasonable, considering the large range
of features it offers.
The Datacat
If you want to do anything more than
simply use your PC-based music system
to 'play' MIDI files like a high-tech
canned orchestra, you need a musical
input device or controller. For many
people this will tend to be a keyboard.
While quite a few of the low-cost
electronic keyboards are fitted with
MIDI sockets and can be used for this
purpose, they're generally not ideal. You
can certainly get note on/off codes from
them, and generally voice 'patch'
programming codes as well, it may not
be easy to use them for convenient input
of other control information.
On the other hand, 'serious' MIDI
keyboards can be rather expensive, and
can represent overkill for someone who
just wants to experiment with computer
music. They're also pretty large!
There's a need, then, for a smaller version of the traditional MIDI keyboard
controller - offering many of the same
facilities, but in a smaller and hopefully
cheaper package. And Kawai's new
Datacat controller is designed to meet
this very need.
The Datacat has a three-octave 37
note keyboard, a little smaller than
standard but still quite easy to use. It
also provides two controller wheels, one
dedicated to pitch bending and the other
able to be assigned to any of a wide
range of MIDI programmable
parameters (modulation, volume, panpot, damper pedal, etc). In addition there
are four function select pushbuttons,
used in conjunction with the top 11 keys
for sending MIDI control codes as well
as programming the second controller
wheel, and another group of four
transpose/octave select buttons. The latter allow the Datacat to . transpose the
keyed notes up or down by up to 12
semitones (each way), and also to shift
the keyboard span either up or down by
four octaves each way. In other words, it
can cover the full 128-note MIDI span.
Measuring only 496 x 197 x 62mm
and weighing 1.6kg, the Datacat is compact enough to fit onto most computer
tables without undue embarrassment. It
operates from either six AA cells, which
fit inside the case, or from an external
9V DC plug pack. And it carries an RRP
of only $299, which probably makes it
about the cheapest way to provide your
system with these facilities.
Trying them out
Kawai Australia very kindly loaned us
demo samples of the GMega, GMega
LX and Datacat units, so that we could
try them out for ourselves. We used
them with a 486/33MHz machine running Windows 3.1, and this allowed us to
try out the Powertracks Pro sequencer
software as well.
Since the test computer is fitted with a
Sound Blaster 16 card, we were able to
use the card's basic MIDI interface with
our own MIDI Breakout Box project
(February 1994) to provide the necessary full MIDI input and output ports.
Similarly since the computer has a spare
serial port, we were also able to try out
the GMega LX's serial interface as well
- after installing the appropriate Windows driver (supplied).
We tried out the GMega LX synthesiser first, and had no trouble at all
driving it from either the MIDI or serial
ports. We used it to play a wide variety
of GM music files, and were frankly
very impressed with both the clarity and
realism of many of the instrument voices
and the overall 'richness' of the sound
when playing complex music. The piano
voices were excellent, and with some
pieces gave an uncanny reconstruction
of an acoustic instrument being played.
Bowed string voices seemed a little less
successful, but this may have been the
fault of the MIDI files we used...
Next we tried its big brother the
GMega, and this again proved very easy
to use as a straight 'GM orchestra in a
box'. If anything its instrument voices
seemed even more impressive than the
LX model, and its piano voices again
particularly convincing. Needless to say
we also tried out many of the additional
voices in the second SP tone bank,
which give you a very wide selection of
alternative 'instruments'.
We also tried programming our own
voices using the GMega's front panel
controls. There's a huge amount of
flexibility here, with the potential to
achieve almost any kind of 'instrument'
you set your mind to - given enough
·time and patience. However we did find
the programming system, using the
GMega's front panel controls, a bit
clumsy and tedious.
Frankly, our impression is that to
realise the full potential of the GMega in
this regard, you'd really need a 'patch
editing' software program which would
let you conveniently manipulate each of
the parameters (preferably via an interactive graphical display), and then
download the complete instrument voice
'patch' to the GMega to try it out. There
are programs to let you do this sort of
thing, but we haven't heard of one
specifically suitable for the GMega.
Apart from this, though, there's no
doubt that the GMega is a far more
powerful and flexible synthesiser than
its LX brother, and provides much
more scope for the 'serious' computer musician.
While giving the sythesisers a
reasonable workout we also had a good
play with the l)atacat keyboard, both
as an input device for feeding tunes into
a sequencer program, and connected
directly to either (or both) synthesisers
as a direct controller. And it too
gave a good account of itself, proving a
very convenient way to input not only
tunes themselves, but also any of the
various MIDI control codes we needed
along the way.
In short, it seems a surprisingly convenient and practical little MIDI keyboard controller, despite its compact size
and low price.
As part of our playing with the synthesisers and keyboard, we also gave the
Powertracks Pro sequencer package a
good workout. This seems quite a good
Windows-based MIDI sequencer, with
the ability to do most of things needed
for fairly serious work on a PC-based
music system.
About the only thing it seemed to lack
is the ability to provide a 'pianola roll'
representation of MIDI channel information. On the other hand, it can print out a
MIDI channel in very presentable standard music notation, on virtually any
Windows printer...
So if your sound card has whetted
your appetite for MIDI music, but is
now becoming a source of frustration
because of its limited resources, these
attractively priced MIDI products from
Kawai are well worth considering.
There's only one problem: after
you've heard your MIDI files played via
the GMega LX or the full GMega,
you 'II never want to go back to your
sound card's synthesiser! +
ELECTRONIC TEST
GEAR TO BUILD
Volume2
Test instruments are important tools for anyone who
needs to work with electronic circuits - whether you're a
designer, a service technician or a hobbyist experimenter.
With the right test instruments, you can tell quite accurately what is going on in a circuit, but without them, you're
often forced to rely on luck and blind intuition.
This book is a collection of some of the most popular
designs that we've produced in the last few years, brought
together and re-presented by popular demand. In each
case, you'll find that as well as the original articles, we've
also included any subsequent notes and errata on the
projects concerned, to make sure that you have all the information needed to make each project a success.
Copies can be obtained by sending $7.50 (including
postage and handling), to:
..,.
d
z
The Book Shop,
Federal Publishing Company,
P.O. Box 199,
Alexandria, NSW 2015.
0
u..
~
a:
w
<
w
a:
0
ELECmONICS Australia, February 1995
51
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Siren Generator Q
8
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trigger input signals. Its solid-state audio recorder IC allows you to
re-record as many times as you like, with a total of 16 seconds
recording time. Also features repeat selection and chime option. In
short-form with PCB & all components
including micro controller IC. All you
need to do is build it.
es249
@Jan'95
Great For Beginners#
Dual-Rall Power Supply Q
As this kit requires no mains wiring, it's the perfect starting kit for
beginners. You can build your very own dual-rail power supply
using an AC plug pack which already contains all the mains wiring.
It provides 11 separate voltages from 1.25V to 15V and has a load
switch and drop out LED. Comes complete with all components,
PCB, hardware, case, front panel
(punched & screened) and AC
plug pack.
Cat K-3201
llflfllliloct'94
s5995
5
@~:~~95. $8995
Sick Of Getting A Flat Battery?
Talking Headlight Reminder Q
Can be used as a reminder alarm to alert you when your
headlights are left on or for a number of other applications. Simply
record your own reminder message (up to 16 sec.) and it will be
continually replayed for 30 seconds. It's simple to build, using a
single sound recorder IC and an external speaker. Comes in short
form with components, PCB, and
hardware items such as switches,
mic. insert, speaker and record
LED.
Cat K-5024
llflfllliloct'94
s4995
Please contact your nearest store for availability as some kits may still be in production.
Everything You Need
To Do It Yourself!
Temperature Controlled
Extruded Aluminium Heat-Sink Boxes
Affordable Soldering Station
Internally-slotted to accept PCBs, they're an ideal choice for
any project that needs heat dissipation. Their black powdercoated finish gives an ultra-professional look to any project.
An incredibly reliable and easy-to-use
temperature-controlled soldering station.
Featuring a large capacity sponge tray,
built-in stand, internal AC mains
transformer and safe 16V operation.
s399s
CatT-1900
Breadboard Kits
Faster, easier and cleaner than working directly onto PCBs,
these breadboards are ideal for low voltage designs.
Small
Medium
Large
CatH-4035
Cat H-4045
Cat H-4025
$9.95
$12.95
$16.95
Ceramic Adjusters/ Alignment Tool
70(1) x 32(h) x 140mm(d)
Cat H-3000
$1995
* 108(1) x 38(h) x
140mm(d)
Cat H-3002
$2495
*Features sliding top panel (immobile
when assembled).
2 Channel UHF
Remote Control Q
0.9mm Flat
2mm Flat
A very handy kit that provides you with remote control for
two separate devices such as a car alarm or solenoid on
boot latch. In a convenient keyring design, it features a
button for each device and can operate in a range of up to
approx. 20 metres with a 30cm antenna. Plus, it allows for
6561 security code options and is DC powered (between
10 & 15 volts). The receiver is a small module that uses
surface mount components, is tuned to 304MHz and is
supplied already aligned and tested. Kit will be supplied
complete with all components, PCB receiver module,
case, and one 2 channel transmitter (fully assembled).
CatT-5202
CatT-5208
Cat K-3260
1.3mm Flat
#0 Phllllps
You'll find these high quality adjusters perfect for computers
communication instruments, VCR, CD and other electronic '
devices. They're made from a combination of high-tech
materials with zirconia ceramic blades and anti-static handles.
Plus, they're non-conductive, non-magnetic, non-static and
long-lasting. At just $9.95 each, you can afford to buy the
complete setl
Cat T-5200
Cat T-5206
CatT-5204
1.8mm Flat
S995ea.
llfMl!ll Jan '95
Car Alarm With Battery Back-Up QQ
This affordable kit places a quality feature-packed car alarm well
within your reach. Based on the OM1681 C Philips car alarm IC,
it's straightforward to build yet it provides similar features to
those found in expensive commercially available units. Such
features include battery back up, presettable entry and exit delay
periods, flashing status LED, automatic resetting after 60
seconds and the ability to automatically operate a central door
locking system with optional interface controller (K-4314).
Includes all components, PCB, hardware including automotive
multiway connector, case & siren with
back-up battery.
Cat K-4312
/flllfllllloec'94
$8995
2 Channel UHF
Transmitter
Additional transmitters
to suit K-3260.
Cat K-3261
Interface Controller To Sult
Cat K-4314
$1695
/flllflllllJan'95
$3995
waves), and with the same amplitude as
the sine and triangle waves.
Looking now at the amplifier section,
waveforms. Thirdly there is an amplifier the diodes are biased by the voltage
using IClb and Ql, with level control divider made of R21, R22, R25 and R26 the selected sine, square or triangle wave
(the centre point of which also provides from SW2 - which has an amplitude of
and an amplitude modulation input.
The oscillator section itself consists of (1/2)Vref for biasing the two OTA's), about 0.7Vpk- is applied via attenuator
R9/Rl4 to the non-inverting input of the
three parts. Firstly there is the OTA in so that they conduct at different volICla, which is not used as an amplifier tages. This has the effect of rounding off amplifier OTA at pin 14.
The level that appears at
but as a switched current source
this input has a peak amplitude
feeding the frequency band
PARTS LIST
of about 20mV. It has to be at
determining capacitor (one of
Resistor•
this low level to minimize disC2-4, as selected by SWl).
(All 0.25W/5% metal film unlesS specified)
tortion without the use of feedSecondly there is the ICla in.
4 Band1%
58and1%
back. This particular OTA
ternal buffer, which is used to
R1,2,8,10 3.3k
OrgOrg RedBm OrgOrgBlkBmBm
device actually has inbuilt
R3,23,24 6.8k
Blu Gry Red Bm Blu Gry 8lk Bm Bm
buffer the output of the OTA.
R4, 11
4.7k
Yel VJO Red Bm Yet Vlo 8lk Bm Brn
linearising diodes (shown as
Thirdly there is IC2, a 555
R5,6,18
2.7k
RedVloRedBm RedVioBlkBmBrn
part of the OTA circuit symtimer IC, which is being used
R7
15k
Bm Grn Org Bro Bro Gm 8lk Red. Bm
bol), which can be biased to
here as a comparator with input
A9
22k
Red Red Org Brn RfKj Red Blk Red Bm
remove this particular nonhysteresis levels of (l/3)Vref
R12
680 ohms Blu Gry Brn Bm Siu Gry 8lk 8lk Bm
R13,14
390 ohms Org Wht Sm Bro Org Wbf 8lk Blk
linearity, but these were found
and (2/3)Vref.
R15
18k
Bm Gry Org Bm Bm Gry 8lk Red Brn
to reduce the gain too much,
The way the oscillator works
A16
27k
Red Vio Org Bm Red ViO 8lk Red Bm
and
so were not used.
is as follows. When the voltage
R19
68 ohms Blu Bry Blk l3rn
Btu Gry 8lk Gld Sm
In the absence of any
across the selected capacitor is
R17,20
10k
Bm Blk Org Bm Bm 8lk Blk Red Bm
amplitude modulation input,
R21,26
1.5k
Bm Gm Red Brn Bm Gm 8lk Bm Bm
below (l/3)Vref, the output of
R22,25
100 ohms Bm BlkBm Bro
Bm Blk 8lk 8lk em
the gain of the amplifier, and
IC2 goes high (Vref), causing
R27
47 ohms Yel Vio Blk Bro
Yet Vio 8lk Gld Bm
hence the output level, is
the OTA to charge the capacitor
R26
8.2k
Gry Red Red Bm Gi:y Red Blf< Bm Brn
determined
by the control curwith a constant current equal to
VR1
2k
5mm vertical trimpot
rent (Iabc) fed into pin 16 via
Iabc. When the capacitor voltVR2,4
5k
16mm Bnearpotentiometer
Rll, from VR4. R12 raises the
VR3
5k
5mm certical trlmpot
age exceeds (2/3)Vref, the outvoltage at the bottom end of
put of IC2 goes low (OV)
capacitors
16135VW RB electlQlytic
C1,7
10uF
VR4 to about 0.8V, because
causing the OTA to discharge
C2
2.2nF
100V MKT (.~. 222)
this is about the minimum
the capacitor at the same rate.
100V MKT (.022, 223)
C3
22nF
voltage
required to start Iabc
The resulting waveform across
100V MKT (22(>n, 224)
C4
0.22uF
the capacitor is a triangular
flowing (the voltage at pin 16
100VW RB electrolytlc
CS
2.2uF
SOV ceramic (0.01uf, 103)
C6
10nF
varies between about 0.8V and
wave, which is symmetrical
cs
5.$pf
SOV ceramic
1.4 V, depending on current
about (l/2)Vref with a peak-to1OVW RB electrolytic
C9
470uF
peak amplitude of (l/3)Vref.
and
temperature).
C10,11
100uF
16VW AB electrolytic
If there is no frequency
Amplitude modulation is
SOVW RB electrolytic
C12
1uF
modulation applied, the
achieved by applying an
Sflmlconductars
charge/discharge current from
AC
voltage
to
the
01·6
1N4148or1N914 signal diode
07
1N4007 p<>Wer diode
the output of the OTA is equal
amplitude modulation input,
zo1
a.av 400mW zener (1 N957)
to the control current Iabc
causing labc - and hence the
01
BC549 NPN small signal BJT
which flows into pin 1 via R2,
amplifier gain - to vary in
02
BC559 PNP small signal BJT
from VR2.
proportion to the modulation
IC1
LM13600 dual OTA
Trimpots VRl and VR3 are
signal voltage.
IC2
TLC555 CMOS timer
used to set the upper and lower
The load for the OTA is
Mlsctlllllneaus
3-pole 3-position rotary swttch (SW1 ); 2-pole three- pOsltiQn
- frequency limits respectively.
formed by R15 and R16, with
slide swttch (SW2); 9V battery •snap' cable; PCB, 43 x 88mm,
The values of VRl and VR3
C8 added to remove overshoot
code ZA1202; 30Cm length of rainbow cable; so~r. etc.
were chosen to suit a one
from the square wave. A single
decade frequency range.
resistor to ground could have
the triangle wave in a way that been used as a load, but the voltage
An AC voltage applied to the frequency modulation input causes Iabc, and produces a reasonably low distortion divider was used to raise the quiescent
hence the oscillator frequency, to vary in sinewave, at the common connection output voltage, compensating for the
proportion to the signal voltage.
side of the four diodes. This sinewave voltage drop introduced by the DarNext we'll take a look at the triappears at the waveform selector switch lington buffer, and so increasing the
angle to sinewave converter. The buf- terminal SW2/2.
maximum available output voltage.
fered triangle wave from pin 8 of ICla is
The same triangle wave output is also
The output amplifier is a common colapplied via RS to what is known as a fed to SW2/l via R7, which reduces the lector stage using the IClb buffer, with a
breakpoint waveshaper network, consist- amplitude to that of the sinewave.
lOmA constant current sink in the emiting of Dl-4 and R21-26. The top half of
To provide a squarewave, the out- ter. This gives a peak output current
the network shapes the half of the tri- put of IC2, which alternates between capability of 1OmA. Resistor R20 is
angle waveform that is higher than Vref and OV, is applied to the resistor added to keep C9 charged in the absence
(l/2)Vref, while the bottom half of the network R4-6. The output of this net- of any other DC load, preventing large
network shapes the lower voltage half of work, which is applied to SW2/3, is a
transients when the output of the functhe triangle. waveform.
squarewave which is symmetrical about tion generator is connected to a circuit
The way the converter works is that (l/2)Vref (as are the triangle and sine under test. +
'Discovery' Series Function Generator
em
66
ELECTRONICS Australia, February 1995
AUSTRALIA
WIDE
1995 ELECTRONIC
COMPONENTS CATALOGUE
YOURS FREE with this Month's Electronics Australia Magazine.
Our 1995 Catalogue now contains even more fantastic products and greater value than ever
before. We still offer the technical help that only a staff of electronic enthusiasts like yourself is
able to give. Of course, in addition to this we have our FAMOUS OVERNIGHT DELIVERY Australia
Wide, with Credit Card phone orders up to 4pm (E.S.T.) Monday to Friday. Quality products at
DIRECT IMPORT PRICES, means you save up to 50%!
Regards, Jack O'Donnell, Managing Director
High Performance REDBACK
Dual Cone 200mm, 8" Speaker
These speakers are the very same as used by contractors
Australia wide in major background music and paging
systems. They exhibit very high sensitivity due to the
unique magnet and cone arrangement. Excellent for
extension speakers for games rooms, patios etc.
Input Power: .................. 8W nom, I5W max
lmpedance: ...........................................8 ohm
Resonant Freq.: ..................................... 80Hz
Freq. Response: ............................ fo - I8kHz
SPL: ......................................98dB (Iw/0.Sm)
$16-50 ea
This Month Bu}!_ 2
for the Price of 1
C 2000 Normally
50
Only $16"
Pair
House Break-Ins Are On The Increase
Protect Your Home or Business from
Intruders with this 'State of the Art' Alarm
4 Sector Alarm Panel
The deluxe S 5485 4 sector alann panel features a
user selectable 4 digit pin number allowing you to
arm and disarm the alarm via the inbuilt digital keypad. By using 'End of Line Resistor' technology, all 4
independent sectors accept almost any type of sensor
(Normally Open and Normally Closed). Any sector
can be individually isolated, (e.g. when at home you
may want to tum on perimeter sensors, allowing
movement inside). Includes a 24 hour panic and tamper sector. Alann pre-warning reminds you to disarm
on entry. Constructed in sturdy steel case with lock.
Includes easy to follow installation instructions.
Nonnal Value o/$249",.
This Month Only $149
Digital Storage
C.R.O. Adaptor for
M 9127 I6V AC IA Plug Pack to Suit $19.25
S 5067 3Ah Backup Battery to Suit $47.95
P.C.'s
Kit
(See EA
Jan '93)
This great
kit enables
a P.C. user to capture a
waveform and zoom in to segments of
interest then save them to disc. The unit has
32K of storage memory and a sampling rate
of over 600K samples per second. Input
level of up to 2.5 Volt. Full sampling rate
between I5K sis to over600K s/s. Input
impedance of IM ohm.
K
PC . .,
2806
5 25
50
K 2805 Normally $63·
Disk Software
$19.95
This Month Only
$.55
quency counter kit
offers high performance wi out a high
price tag. Features include an accurate 4
digit bright LED display, 5 ranges of IOkHz,
IOOkHz, IMHz, IOMHz, SOMHz and a BNC
type input connector. Ideal for servicing
etc. Supplied complete with professional
screen printed aluminium front panel.
95
K 2512
$89·
FREECALL 1-800 999 007
Doc.JH095
Stereo TV Sound Receiver - 2
mon audio socket earth is also connected to the earth of the BNC
video socket, and connects to the PCB earth via the shield braid
of the video lead - which is connected at each end, like the
leads between the PCB and the volume control.
After completing all of the connections, spend a few minutes
checking over your work to ensure that everything is according to
plan. Then you should be ready for the testing and alignment phase.
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ELECTRONICS Australia, February 1995
Testing and alignment
For this operation, you'll need to connect the antenna input of the
receiver's tuner module to your TV antenna, perhaps via a splitter
unit so that your existing TV set still receives signals as well. You'll
also need to connect the R and L audio outputs to a suitable stereo
amplifier, so that you can monitor the audio, and also feed the
receiver's video output to either a vid~o monitor, to your TV's
direct video input if it has one, or via a VCR if it hasn't. (Monitoring the picture makes tuning the sound receiver much easier.)
Before applying the power, tum the volume control fully anticlockwise and the mode switch to Mono. Also turn preset pot RV?
to the fully anticlockwise position, and RV6 to its centre position.
Then switch on the power, and with your DMM or multimeter
quickly check the voltages at the output of the bridge rectifier. You
should find about +21 V at the cathode (band) end of D3 or D6, and
-21 V at the anode end of D4 or DS. These voltages are relative to
PCB ground, of course - you can use the case of either the tuner
or IF modules as a convenient ground for your meter.
If these basic voltages seem OK, measure the voltage at the
banded end of zener diode D9; it should measure very close to
+ 33V. Then check the regulator output voltages, at pin 4 of either
U2 or U3(+12V), piri 11 of the same chips (-12V), the wire link on
the PCB near R17 and Rl8 (+9V), and pin 19 of Ul (+SV). Take
care when you're measuring the voltages on IC pins, by the way; if
the test probe should slip off the pin, it can cause short circuits and
possible damage...
Should any of these voltages be absent, or significantly different
from the expected value, switch off the power immediately and
check for wiring mistakes - reversed diodes, etc. Needless to say,
you'll need to fix any problems before proceeding.
Assuming that things are fine this far, now try measuring the voltage on the wire link just to the rear of RV?, near R14. It will
probably measure around +24V, and the idea is to adjust RV? with a
small screwdriver until the voltage rises to slightly over +28V. This
completes the receiver's basic DC checkout and setting up phase.
It's unlikely that you'll be seeing any pictures on the monitor at
this stage, or hearing anything other than noise if you turn up the
~eiver's volume. control. The next step is therefore to set up the
preset tuning. To do this move the rear panel Tune/Normal switch
SW3 to its 'Tune' position, if it isn't already in that position, and set
the channel selector switch SWl to position 1. Then with the
volume control turned clockwise to let you hear things as well as
see them on the monitor, slowly turn preset pot RVl until you can
at least get a clear picture for the station you want to receive on
setting 1. The correct tuning position is where you get a clean, sharp
picture, just before it starts breaking up with sound information.
When you believe you 're at the right spot, try flicking SW3 briefly to the 'Normal' position. If the picture doesn't change, or changes only slightly, you are correctly tuned; otherwise you may have
to switch back to 'Tune' and try again.
(If you have trouble getting a good picture at the point where the
AFC results in stable tuning, you may need to make a slight adjustment to the tuner module's IF tuning slug. This is the small slug
accessible via the hole just near the IF OUT pin; it's very small, so
you'll need a very small ceramic or plastic alignment tool. Since it's
also risky to adjust it without instruments, be cautious and note
I
in exactly the same way, doing all of
your tuning with SW3 in the 'Tune' position, and just flicking it back to the
'Nonna!' position to check each setting.
With all six channels set up in this
way, the last tuning step is to switch
SW3 back to the 'Nonnal' position, and
leave it there.
Sound alignment
Now you should be ready to align
the sound coils. This is not unduly difficult, and you should be able to do it
quite quickly. Frrst of all, turn SWl to
any of your local channels. Then turn up
the volume; probably most of what
you 'II hear will be noise, but there will
probably be a small amount of
programme sound.
',Now, using a suitable plastic or
ceramic alignment tool, slowly adjust the
tuning slug of 36MHz coil L2 in one
direction and then the other, until you
hear the noise level reducing, and the
sound signal increasing. Whichever
direction achieves this is the correct
direction to keep turning, until you reach
the optimum setting - where the noise
will pass through a broad null, and the
signal through a broad peak. (You may
need turn back the volume control as you
proceed, to prevent overloading your
amplifier or your ears.)
When this optimum setting is found,
L2 is correctly set and you can turn your
attention to L3, the 5.50MHz coil. Here
again, it's basically just a matter of adjusting the slug in L3 until you get the
loudest undistorted sound, and the minimum background noise. As the exact optimum setting can be a little tricky to
find, try deliberately turning the slug to
either side, until you hear the noise increase again each time. Then note how
far you've turned between the two 'noise
just audible' settings, and split the difference to locate the optimum point.
With L2 and L3 both set up, your final
step is to set up IA. This is done in virtually the same way as L3, but with
mode switch SW2 set to the 'Bilingual2'
position so you're listening this time to
the signal from the 5.74MHz subcarrier.
It will also be necessary to make sure
you 're tuned to a stereo station; otherwise there won't be any 5.74MHz sound
signal to peak up on!
Other than that, it's again just a matter
of adjusting the slug in IA until you get
moau1e IS available: the HL-PIF-38MC02,
which appears to differ mainly in that its
video IF is 38.9MHz, rather than
36.875MHz.
Although we have not had the opportUnity to test this alttmative IF module,
It should be possible to use it providing
the SAW filter used in the receiver's
sound channel is also changed, to a
Murata SAF38.9MVB70Z. As the type
number suggests, this filter is again
designed tor 38.9MHz, and Is in fact
specifically designed for quasi-split
SATELLITE
TV SYSTEM
For many years you have probably
looked at satellite TV systems and
thought "one df1t".
sound.
As far as we can see, no other component changes should be needed to use
these alternative parts. However in view
of the move in intermediate frequency,
you will pmbably need to adjust the IF
output tuning slug In the tuner module, to
achieve optimum pieture and sound
quality. Take care, though; adjusting this
slug without instruments is risky, so
make a careful note of the direction
you tum it (anticlockwise would be correct), and how far - so you can restore it
if you strike trouble.
the loudest undistorted ·sound, and the
minimum background noise.
Turning mode switch SW2 now to the
'Stereo' position should at last result in
full stereo sound to emerge from your
hifi system speakers, and your receiver is
very close to finished. The only remaining adjustment is the setting for RV9, the
stereo matrix balancing pot.
This is not a critical adjustment, and in
many cases the initial 'halfway' setting
of this pot is likely to be fine. However if
you want to set it up accurately, the
easiest way is to monitor the 'L-R'
audio output with one channel of your
amplifier, while viewing a programme
with an essentially 'front centre' mono
source, in a relatively 'dead' environment - someone giving the news, for
example. The idea is to adjust RV9 for
minimum output from the L-R channel.
With this adjustment done, your Stereo
TV Sound Receiver should be complete.
All that remains is to screw the top on
the case, and settle down to enjoy yourself watching TV with the added dimension of stereo sound.
Of course if you wish to take advantage of the Receiver's L-R, L+R and
subwoofer outputs, for a low cost but
quite impressive 'surround sound' effect,
so much the better. You'll just need a few
more amplifier channels, to handle the
extra signals. I can recommend Rob
Evans' little Shoestring Amplifier for this
- it fills the bill very nicely. +
Your own
K-band system
from only:
~~:::JI $995
HERE'S WHAT YOU GET:
·,
• Prime focus or offset dish
configured for your location.
• Super low noise LNB/feedhom.
• 25m low loss coaxial cable.
• DYNALINK 50 channel stereo
satemte receiver, with remote
control. Pre-programmed to
Optus frequencies.
• Pointing co-ordinates for
your location.
Ask about our regular
newsletters and
Customer BBS. Send
coupon for your ftae
info pack, listing
all items and prices.
CALL FOR
YOUR NEAREST
RE-SELLER
Direct Importer: AV-COMM PTY. LTD.
PO Box 225, Balgowlah NSW 2003
Tel: (02) 949 7417 Fax: (02) 949 7005
YES GARRY, please SIKld me more
infonnatJon on K-band satelllte systems.
Name: _ _ _ _ _ _ _ _ _ __
Address: _ _ _ _ _ _ _ _ _ __
---------
P'code:__
~
ACN 002 174 478
W
:
~----~-----------------------~ a:
ELECTRONICS Australia, February 1995
ee .[J:.~:
Y16084
:];];:.;:
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Y16082
240VAC MAINS SIRE PROTECTION
.
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BNG 50 OHM 3M NETWORK GABL£ M-M
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one large and sixteen small
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Twenty-six storage sections
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1101151114148
110105 llU802
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$0.06 SO.OS S0.04 $0.03
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$2
$2
1 soln-:ua
·
50
$2.20
Z10141(G)$0.20 $0.18 $0.15 $0.12
Z10143(Y) $0.20 $0.18 $0.15 $0.12
Z10145(0)$0.20 $0.18 $0.15 $0.12
1
1()
by PETER LANKSHEAR
Good advice: 'Caveat Emptor'
The Latin phrase in this month's column, which is written especially for newcomers to radio
collecting, is the time-honoured reminder that it is a purchaser's responsibility to be on guard. I was
prompted to write on this topic when recently I encountered an instance where an enthusiastic, but
inexperienced, collector got a little out of his depth ...
An acquaintance of mine, who is a
relative novice to the hobby of vintage
radio, has been impatient to obtain a
'cathedral' model radio and was
delighted recently to have tracked down
a classic example - a 1931 Atwater
Kent model 80, rare enough in New
Zealand and even rarer in Australia. It
was not in working condition, but had
been kept as an ornament. After much
persistence, the reluctant owner, who incidently, is not a collector, was persuaded
to part with radio in exchange for a sizeable sum of money.
I was invited by the excited
new owner to approve the purchase, but even at first glance,
it was apparent that it was far
from being in original condition. Immediately obvious was
an extra control knob in the
centre of the front panel and
from even a cursory look at the
chassis it was apparent that
there were non-standard parts
fitted.
Although it is unreasona?le
chassis should still be as original as possible. In this case, as it was hoped that
eventually the receiver would be fully
restored and operating, it was time for a
critical look.
Modern IFT's
Comparison of the photograph of the
chassis with that of a model 80 in original
condition gives an idea of just how much
modification there has been. Where there
should be a single large circular IF transformer, there are two much more modern
square IF cans, clearly labelled 'Sickles',
and the substitute aerial coil has a
shortwave winding implying
bandswitching, which is an anachronism
in a 1931 A.K. receiver, and of course is
the reason for the extra control knob.
Of the original valve sockets, only
those of the rectifier and power output
stages remain. Notably absent is an Atwater Kent oddity, a type '27 oscillator
valve mounted inside the oscillator coil
and its open topped shield. Missing from
the rear of the chassis are the name plate
and the aerial trimmer capacitor with its
knob. In fact, apart from two valve
sockets and two remaining
shield cans, practically the only
original components remaining
are the tuning capacitor and the ·
power transformer which, inciden tl y, has tell-tale black ·
deposits around its cover - a
sure sign that a rewind will be
required. That one item alone,
with freight, would not leave
much change from $100.
With the chassis upended,
there is more evidence of van1
.l-1!--
A--.-.-...• •1. ........ -11 ....,..+:--
i
I
I
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*Features sliding top panel (immobile
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2 Channel UHF
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A very handy kit that provides you with remote control for
two separate devices such as a car alarm or solenoid on
boot latch. In a convenient keyring design, it features a
button for each device and can operate in a range of up to
approx. 20 metres with a 30cm antenna. Plus, it allows for
6561 security code options and is DC powered (between
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case, and one 2 channel transmitter (fully assembled).
JilPJan'95
QQ
This affordable kit places a quality feature-packed car alarm well
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periods, flashing status LED, automatic resetting after 60
seconds and the ability to automatically operate a central door
locking system with optional interface controller (K-4314).
Includes all components, PCB, hardware including automotive
multiway connector, case & siren with
back-up battery.
Cat K-4312
2 Channel UHF
Transmitter
Additional transmitters
to suit K-3260.
Cat K-3261
Interface Controller To Sult
Cat K-4314
$1695
x
Cat K-3260
$995ea.
Car Alarm With Battery Back-Up
$1995
JilPJan'95
s399s
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The Way Multimedia Works
Explains everything you need to know
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Cat B-6552
fl
ra.
Collaborated with major semi_
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•
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•
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$6995
Controlling The World
With Your PC
Hook up circuits to your PC! This manual
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•
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$3995
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unlden.
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Adjustable Low
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LM2941CT
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ISD1461 P
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$
3995
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Construction Project:
VERSATILE SOLID STATE
AUDIO RECORDER
Microprocessor based, this project is a lot more than just a solid state audio recorder. You can
record up to eight short audio clips, and then have it replay different clips in response to different trigger input signals. This gives it the potential for use in a wide variety of applications - from
reminding you to use your seatbelt and turn off your headlights, to delivering your amateur radio
callsign at regular intervals.
by BOB PARKER
'Versatile Multiple Announcement
Circuit', or 'VMAC' for short, was
about the most descriptive name I
could dream up for this new project.
It's an extremely flexible ·general-purpose circuit which allows you to record
not just one, but up to eight different
short voice messages, announcements,
or maybe even sound effects, in a
solid-state audio recorder IC. Then one
or more of these recordings can be individually played back, by activating
their corresponding 'trigger' inputs. It's
up to you and your imagination to
decide what external devices you'll
connect to the inputs (and outputs)!
The recorder IC will retain your
recordings, even with power disconnected, for about 100 years(!). However,
you can re-record on the chip at any
time, should you decide to change or update it. This can be done as many times
as you like, but you do need power for
the recording operation.
Using simple 'DIP' switch settings,
any of the high impedance, voltageprotected trigger inputs can be easily individually configured to respond to either
56
ELECTRONICS Australia, February 1995
a 'high' or a 'low' voltage level, or a
simple contact make or break.
Also programmable by DIP switches,
any recorded segment can be set to play
just once, or repeat endlessly, if its input
stays triggered. So VMAC can tell you
about a change in conditions, i.e., that a
door you've fitted with a reed switch and
magnet has opened or closed. Or it can
keep repeating a warning about an abnormal condition, e.g., an engine oil
pressure alarm.
In addition, the circuit can generate a
pleasant, attention-getting 'chime' sound
prior to each announcement, if desired.
VMAC has a loud on-board 2W
amplifier to drive an eight ohm speaker,
plus a line level output of about 200mV
RMS which could feed a public-address
amplifier, amateur radio transmitter, etc.
Provision has also been made for
mounting an optional relay, which
operates during your announcements, on
the board. This can be used to activate
said PA amplifier or transmitter, or perform some other low voltage switching
function you might have in mind.
The VMAC 's power needs are
reasonably flexible. It will operate from a
DC supply of lOV to 20V and uses
25mA or so in its standby mode, but can
draw several hundred milliamps when
driving a speaker hard. For most mainsp owe red situations, a nominal
12V/300mA plugpack supply should be
more than adequate. Of course it will
also work well from a car's electrical
system (but remember to put a lA fuse in
its supply lead!).
Many applications
Before giving you some examples of
possible applications for VMAC, I
have to state that Information Storage
Devices Inc, the manufacturers of the
audio recorder chip, reserve the right to
exclude the use of their devices from
the following: medical equipment,
greeting cards and Christmas ornaments. If you think you might want to
use a VMAC in any of those areas,
please contact ISD's Australian agents,
R&D Electronics, phone (03) 5580444, for clarification of the situation.
Apart from the preceding, the uses for
VMAC are many and varied. A large
area of potential application would be in
industry, telecommunications and
security monitoring, where it could supplement or replace existing visual and/or
acoustic alarms and indicators.
A voice indication of exactly what the
problem is would be much more useful
than simple alarm beepers. But there are
lots of other possible uses, too. Radio
'hams' could record a couple of versions
of a 'CQ' message and transmit them by
pushing different buttons, or under control of a timer/sequencer - or use
VMAC for repeater identification and
status indications (instead of those robotlike speech synthesisers).
The VMAC could probably be of assistance to the visually-impaired, too. For
example, a mate of mine suggested using
one to help a blind person learn the controls for operating a mobile radio base
station, while another has drawn attention to possible sight-impaired and multilingual uses in the tourism,
accommodation and travel industries.
In your house you could connect each
of several doorbell buttons to its own
trigger input, and record an appropriate
announcement for each one. Or install
the circuit in your car and use it as an
audible addition to the warning lights,
plus a 'lights on' reminder, etc.
Model railway enthusiasts could possibly 'dub' steam train sounds, etc.,
from tape recordings, and connect a
A top view of the 'ruggedlsed' version of the VMAC, with PCB mounting terminal
strips fitted to the board instead of PCB pins for the off-board connections. This
board has also been fitted with the relay and Its driver transistor.
VMAC to their layout- using the trains
to trigger it via reed switches, opto sensors and so on.
So if you can think of uses for VMAC,
keep reading! In a forthcoming article I
hope to be bringing you some details of
applications we've already thought up...
Recording time
Each of your announcements can be of
any length you like, as long as they all
add up to a total of no more than 16
seconds. This mightn't sound like much
time, but make a list of announcements
you might like to have, using a sensible
number of words for each one (e.g.,
"There's someone at the front door!" or
"Oil pressure warning!"), and use your
faithful digital watch to measure how
long it takes to say them all.
You '11 probably be surprised, as I was,
to find that you can fit a lot of words into
16 seconds if you're slightly careful. And
naturally, the fewer announcements you
need, the more time you have available
for each of them!
ELECTRET
MICROPHONE
~
I
I
I
INPUT
CIRCUITRY
ISO 141611420
AUDIO
RECORDER/
PLAYER IC.
Z86E0408
MICROCONTROLLER
ICS
IC2,3,4
IC6
I
~·
16xlNPUT
OPTION SWITCHES
CONTROL
SIGNALS
DATA
LINE
OUTPUT
'CHIME'
SIGNAL
Bx TRIGGER
INPUTS
-
MODEBUTION
-
2WAMPLIFIER
RECORD BUTTON
Flg.1 :, A block diagram showing the overall configuration of the VMAC unit. The Input circuitry provides a very flexible
triggering system, so that the micro can replay any selected audio clip from the recorder chip IC6.
ELECTRONICS Australia, February 1995
57
Versatile Solid State Audio Recorder
If a total time of 20 seconds would
better suit your needs, you can install
an ISD1420 chip on the board instead
of the standard ISD1416. However
the ISD1420's frequency response
suddenly stops at 2.7kHz rather than
3.4kHz, making your voice sound a
bit muffled ...
How it works
Referring to Fig. I, the heart of the circuit is IC6 - an Information Storage
Devices ISD1416 audio recorder/player
IC. You've probably seen the ISD ICs in
other magazine projects, and may have
gained the impression that all they can
do is record just a single message then
play it back again, with the possible options of pausing and repeating.
In fact these extremely sophisticated
devices have also been designed to
selectively record, play and 'fastforward' through multiple messages.
All you need is the appropriate external
control logic circuitry, to take advantage of these features. (Sounds easy
enough, doesn't it? Needless to say, it
took quite a bit of work ...)
Now if you were to design this circuit
around ordinary small or medium scale
integrated chips, it would probably take
two dozen or more of them to implement
all the functions of VMAC, which would
make it impractically large, expensive
and complex. So I decided to take the
more elegant approach, and use a micro.
In fact ICS is 'the brains of the outfit',
which replaces those dozens of simpler
ICs. It's a Zilog Z86E0408
microcontroller ('Z86'), containing a
program written by yours truly, which
supervises and controls almost every
aspect of VMAC's operation.
For those interested in the details, the
Z86E0408 is the smallest available member of Zilog's 'Z8' microcontroller family. Despite its little 18-pin package, this
is a high performance eight-bit CMOS
device containing lKB of one-time
PROM, 124 general-purpose registers
plus numerous control and port registers,
two versatile timer/counters, two analog
comparators, a sophisticated interrupt
system, power-on and 'watchdog' reset
circuitry, and and on-chip crystal oscillator. It has 14 input/output lines available.Its instruction set is quite simple
and very efficient, and I'm constantly surprised by how few instructions
it takes to perform even quite complex tasks!
All VMAC's timing, including the
chime frequency and duration, is derived
from the micro's master clock oscillator,
58
aECTRONICS Australia, February 1995
which uses a cheap 3.58MHz NTSC
'colourburst' crystal.
A block diagram of the Z86E0408
device itself appears in Fig.2, while Fig.3
shows the full schematic for VMAC.
Inputs and switches
As you can see in Fig. I and Fig.3,
the eight trigger inputs from the outside
world, plus the logic O's and l's from
the I6 input option DIP switches, arrive at IC4, 3 and 2. These are all
eight-bit parallel-in/serial-out shift
registers, which can be either 4014 or
4021 chips. These convert all 24 'bits' of
information to serial form, which is then
moved in its entirety into the Z86, about
100 times per second. This method of inputting the data has been made necessary
by the fact that we need to look at a total
of 24 bits, while the Z86 has only I4
input/output pins - and many of them
are used for other purposes anyway!
Inside the Z86, the data is subjected
to timing and logical operations which,
after 'de-bouncing' the inputs, eventually form a 'list' of any messages
which need to be played, based on the
Input
Port3
Counter/
llmers (2)
Interrupt
Control
Two Analog
Comparators
VO
(Bit Programmable)
input conditions and DIP switch settings.
If any input trigger condition of more
than 30ms duration occurs at any time,
the Z86 will 'grab' it and add it to its
'play list'.
Playback sequence
When triggered, the Z86 'fast
forwards' IC6 through its memory from
the first to the last recorded segment in
sequence, dropping to normal speed and
playing any segments which are on its
'list'. If lower-numbered segments are
triggered while a high-numbered segment is playing, it 'loops around' and
starts the process again from segment
one. A side-effect of this process is that
under rapidly-changing input conditions,
messages mightn't be played back in exactly the order they were triggered in so please keep this in mind!
As you can see in the photos, there are
two 8-way 'DIP' switch packages on the
board. On each, counting from left to
right, the individual switches number 1
to 8, corresponding to trigger inputs and
recorded segments 1 to 8.
The right-hand switches (SW2 A-H)
are the 'polarity' ones, and they determine what input voltage level will trigger
GND
Vee
XTAL
Machine
- - - - - . ..------vrlimlng & Inst.
Control
ALU
FLAG
OTP
Prg. Memory
1024 x8-Bit
Register
Pointer
Register File
144 x 8-Bit
VO
Flg.2: The Internal architecture of Zllog's Z86E0408 mlcrocontroller chip, which
Is used as the 'brains' of this proJect.
a given switch's corresponding recorded
segment. If the switch is open ('OFF'),
that input will trigger when its voltage
drops to a low logic level (OV - +2V).
Conversely a closed or 'ON' switch will
cause an input to trigger when its voltage
rises to a high logic level (+3V - +20V).
Because of pullup resistor pack RP3,
all unconnected inputs are already automatically sitting at +5V - a 'high' level.
So the polarity sw~h for each unused
input should be left open ('OFF'). More
about connecting the inputs to external
devices, later...
Repeat selection
The left-hand DIP switches (SWl AH) are the 'repeat' option ones. If a
switch is open ('OFF'), it means that
when its corresponding input changes
from its normal to its triggered state, the
VMAC will play back the recorded segment belonging to it, once. Then the Z86
will ignore that input until it has first
returned to its normal condition, and
again gone to its triggered state.
For example, say Input 1 was connected to your car's rear window
demister, SW2A was closed (to trigger
on a HIGH voltage level), and SWlA
was OPEN (for non-repeat). Then when
you tum the demister on, the VMAC
would say "Rear demister on!" (or
whatever) just once, despite the ongoing
trigger condition.
If a repeat option switch is closed
('ON'), the VMAC will continue (irritatingly!) to repeat the segment associated
with that input, for as long as that input
remains triggered.
Chime option
In contrast with the preceding, the
chime option is absolutely straightforward! If you want VMAC to generate a
chime prior to each message, simply
park the 'jumper' between the centre
and left-hand side pins. For no chime,
place it between the centre and righthand side pins.
Recording mode
Now you know how VMAC plays
back your announcements, messages or
whatever, let's discuss how to record
them in the first place!
In the photos you'll have noticed two
control buttons; the one on the left is the
MODE button, and the other is the
RECORD one. The recording process
begins with you making a list of your announcements, starting from segment
number 1 up to the maximum segment
number 8, in numerical sequence.
When you're ready, and with the
VMAC currently not playing anything,
press and continuously hold down the
MODE button for the duration of the
recording session. Then, pressing the
RECORD button as well, speak your
first message (segment 1) in a normal
voice, about 150mm from the
microphone. The LED will light to indicate that recording is taking place.
Immediately you finish speaking,
release the RECORD button - but keep
holding down the MODE button. Then
continue this process with segment 2,
etc, until all your announcements are
safely stored in the chip. The MODE
button must remain pressed for the whole
recording session, but the RECORD button is pressed only during the recording
of each segment.
If the LED goes off while you 're
recording, it indicates you've used up all
of IC6's storage space. Next time you're
Flg.3: Here's the full schematic for VMAC. It may look a little complex, but the hardware operation Is fairly straightforward
thanks to the 'lntelllgence' of the author's firmware - programmed Into the mlcrocontrol/er IC5.
ELECTRONICS Australia, February 1995
59
Versatile Solid State Audio Recorder
going to have to either speak faster, use
less words, install an ISD1420 chip - or
build a second VMAC board and make
the kit suppliers happy!
When you release the MODE button,
the VMAC will play back the entire contents of IC6 - or the first eight recorded
segments, whichever comes first. A
chime sound will precede each segment
if that function is enabled, and the relay,
if installed, will operate for the duration.
If you 'fluffed your lines' and want to
cancel playback prior to another recording effort, hold the MODE button down
until the end of the segment currently
playing, then release it. This will return
the system to its 'idle' mode.
A minor problem with the way the
ISD1416 chip works in this application is
that you can't re-record just one message
and leave all the others as they are. You
must record all of your messages again,
if you make a mistake or want to add
new ones. Any time the VMAC is idle,
you can simply press the MODE button
briefly without recording, to play everything back. This is handy for setting up
audio levels, without the need to manually trigger any inputs.
In more detail
Now let's have a closer look at some
details of the complete schematic
diagram in Fig.3.
Each of shift register IC4's inputs senses the logic level on its external trigger
input pin through a lM resistor, Rl-8,
and this allows any trigger input to be
safely connected to an external voltage
of even +/-20V or so - because with
only a few microamps flowing, the IC
input protection diodes simply clamp the
input pin voltages to essentially the IC
supply rails.
Resistor pack RP3 has been provided
to ensure that any unconnected inputs
will be 'pulled up' to the +SV supply instead of 'floating' to indeterminate logic
levels. In addition it allows any input to
directly sense the condition of an external switch connected between it and circuit ground.
drive an ISD1416 in this way, please
contact R&D Electronics for the ISD
data books. A low level on /REC immediately places IC6 in the record mode,
and it's worth noting that Cl3's function
is to 'swamp' stray capacitance which
could otherwise cause a momentary (disastrous) unwanted recording when power
is first applied.
Going in the other direction, the
/RECLED signal, which drives the
'recording' LED, also tells the Z86 when
playback of a segment has concluded.
That's why the LED blinks at the end of
each segment during playback.
On the analog side, the electret
microphone is connected differentially to
IC6's automatic gain control (AGC)
stage inputs, giving excellent rejection of
electrical noise; R23 and C 19 provide
bypassing of any noise on the
microphone's +SV supply. Cl5 and R20
provide the AGC time constants, while
Cl6 and R24 couple the AGC stage output signal, at an appropriate level, into
the chip's main recording input at pin 20.
Supply bypass capacitors are
generously distributed around the
board, for a very electrically quiet
design.
(Audiophiles would note
that ceramic disc capacitors have
been specified for signal coupling;
if they are irritated by a perceived 'porcelain-like' sonic quality in VMAC, I
understand that glass-dielectric
capacitors have a much more
'transparent' acoustic imprint...)
Chime sound
If the chime option is active, prior to
message playback the Z86 generates
and feeds a 'chime-shaped square
wave' into the chime low-pass filter consisting of Rll, Rl2, Rl3 and Rl4,
Cll and Cl2, plus Q2. Its output, an approximate sine wave of decaying
amplitude, is mixed with IC6 's output via
R25 which matches the chime level to
the voice level.
Q3's function is to effectively shortcircuit the audio output, under control of
the Z86, except when a chime signal is
being generated or IC6 is actually
producing an output. Otherwise IC6's
'SP+' pin, alternating between OV and
+2.SV, causes very loud clicks to reach
the output.
Q3's configuration might seem a
bit strange, but this method of
audio muting is quite common in hifi
equipment such as tuners and compact disc players, and works very
well. R29 protects Q3 from damage if
the line output is accidentally connected to an external voltage or the
speaker output.
For maximum versatility, VMAC
uses an LM380 power amplifier chip.
This can drive an eight-ohm speaker to
more than 2W at a supply voltage of
+20V, while it can still do better than
lW when operating from a car's 13.SV
electrical system.
Although the LM380 can drive a
four-ohm speaker, the PCB 's limited
heatsinking might result in the LM380
overheating and shutting down, during
repeated loud announcements.
Note that to take full advantage of
the VMAC's good quality audio, you
will need to use an appropriate speaker
- not one of those tinny little 57mm
jobs. A 'communications' speaker such
as the D-2250 from DSE or the AS-
The ISD1416 chip
The permanent +SV on IC6's A6 and
A7 inputs tells it to interpret AO-AS as
mode control inputs; control is achieved
by manipulating AO (message cueing),
A4 (consecutive addressing) and
/PLAYL (level-activated playback).
The timing and sequence of the control
signals is a bit complicated and would
take up too much space to explain here,
so if you really want to know how to
60
ELECTRONICS Australia, February 1995
Correct To
1
llov 18 b\j VK2VAE o.nd Vl<l!RC$/VJ2R
This complete overlay diagram for the VMAC unit shows both the optional
terminal strips and relay circuitry. As explained In the text, these need not be
fitted If you wish to leave them out.
3185 from J aycar will give good results.
C23 and R28 keep the LM380 electrically stable into any kind of reasonable
speaker load, and C25 bypasses any stray
RF signals which may be lurking about.
Hardware options
Because of VMAC's wide range of
possible applications, there are several
options available to you in its construction and installation. By sawing off the
PCB corners where marked, the PCB
will fit snugly into a common plastic
'UBI' size (150 x 90 x 50mm) utility
box such as Jaycar's HB-6011 or the H2851 from DSE.
If you want to be able to change your
messages and adjust the speaker volume
without removing the box's lid, install
normally-open panel-mount pushbuttons
(preferably the sort that don't click), an
LED mounting sleeve, a lOmm inside
diameter grommet (Jaycar HP-0704 etc)
for the electret mic and a lOk pot, all on
the lid itself.
Then use long wires to extend the
button and LED connections to the
PCB, and a length of thin screened
wire (shield to the negative terminal)
to the microphone, which you push
into the grommet. Use two more
lengths of screened wire (shields to
the ground pin) to connect the pot to
where VRl normally lives. The use of
PCB pins will make this procedure
considerably easier...
As previously mentioned, you can install a 12V SPDT relay on the PCB to
control an external circuit. Examples
are the Jaycar SY-4050 and DSE's P-
8010 - but DO NOT attempt to switch
240V with it! The PCB is not designed
or laid out for mains voltages, and in
any case mains-borne electrical noise
could hang up (or blow up!) the Z86.
By all means control an external 240Vrated and appropriately wired relay with
it, if you need to control a 240V load.
The last option is that PCB-mount
screw terminal blocks can be fitted to the
board if you wish, instead of ordinary
PCB pins, for connecting to the 'outside
world'. The PCB has been designed to
directly accept them, but you'll probably
need to enlarge the holes a bit first.
Construction
Before installing any components on
the board, hold it up to a bright light and
check for any bridges between conductors, or any fine track breaks. If you're
going to be installing the board in one of
the previously-described boxes, now is
the time to carefully cut off the corner
areas so it clears the box's lid- mounting
'pillars'. It's also the time to use the
blank PCB as a template for the box
mounting holes.
Next begin mounting the components. I suggest the use of a temperature-controlled soldering iron running
at about 360°C, and if the kit supplier
has provided thick solder which would
be more suited to building a valve
amplifier, please replace it with something more appropriate such as N-1636
in the DSE catalog!
First solder in the resistors and diodes.
Then you can install the 'taller' parts,
taking the usual care to get the orienta-
tion of the polarised devices correct. This
includes the electrolytic capacitors,
diodes, ICs and sockets, LED, and transistors. The 'common' pin 1 on resistor
packs RPI, 2 and 3 is identified by a dot,
and this goes at the end furthest from IC5
andIC6.
The electret microphone should be
mounted on thin flexible wires about 30
to 50mm long - otherwise it picks up
loud 'clack' vibrations from the
RECORD button. The negative terminal
is the one connected to its case; install
this last. At this stage it's probably a
good idea to place the chime-select
'jumper' on its centre and left-hand
header pins, before you lose it!
Apart from ICl and IC7, leave all the
ICs in their antistatic packaging until
you've completed the initial checks. I
recommend you use IC sockets for all
the DIP ones except IC7 - this needs to
be soldered directly to the board to allow
efficient heat transfer to the large copper
area beneath it.
With everything but the socketed ICs
on the board, hold it up to your bright
light again and check very carefully that
there are no solder bridges, especially
where tracks run between IC pins. There
are a few areas where a solder bridge
would be catastrophic! Then double
check that all components are properly
soldered in their correct places and the
right way around.
Testing it
Before installing any of the socketed
ICs, connect the power supply pins to a
source of 12V or so and see that the cur-
And finally,
here's the PCB
pattern
reproduced
actual size for
the benefit of
those who like
to etch their
own boards.
5.7'
x 3.3' <1451"'1M x 841"'11"'1) 343 HOLES
ELECTRONICS Australia, February 1995
61
Versatile Solid State Audio Recorder
rent drawn is less than 30mA. If it's
more, check again for misplaced or dis-,
oriented components.
Next check the IC sockets, and see that
you're getting +5V on: pin 16 of IC2, 3
and 4; pin 5 of IC5; and pins 9, 10, 16,
24 and 28 of IC6. You should see about
half your supply voltage on pin 8 of IC7,
and if not, start checking for problems in
that area.
If everything's OK to here, disconnect the power. Then, (this is important) after discharging any static
electricity by touching some nearby
earthed object such as your power
supply case, unpack and install the
socketed ICs - making very sure that
they're the right way around.
Now set all the DIP switches to their
OPEN ('OFF') positions, connect a
speaker between the 'S' and adjacent 'G'
pins, and tum VRl about 30% of the
way around from full anticlockwise.
Reconnect the power and you should
hear two chime sounds from the
speaker, indicating that the Z86 is
operating. If you've installed a relay, it
should operate during the chimes then
immediately release again. At this point
you can record and play back some test
messages, as described earlier in
'Recording Your Announcements'.
Connect a clip lead or similar to the
power supply negative terminal, and
you should be able to trigger any of
your messages separately by grounding
their input pins. If all's well, now you
can record some real messages and
PARTS LIST
Resistors
(All 0.25W unless noted)
R1 ,2,3,4,5,6,7,8,20
1M
R9
2.2k
R10, 14,23,291 k
R11,12
20k
R13,26
10k
R15, 16, 18,25 471<
R17, 19,21,224.7k
R24
5.6k
R27
22k
R28
2.7k
VR1
10k trimpot,
horiz mounting
Capacitors
C1
100uF 25V RB electro
C2,3,4,5,6,7, 10, 16, 17, 18,20,23
0.1 uF disc ceramic
27pF disc ceramic
C8,9
22nF MKT
C11
10nF MKT
C12
1nF disc ceramic
C13,25
220uF 1OVW RB electro
C14
1uF 50VW RB electro
C15
47uF 10VW RB electro
C19
470uF 25VW RB electro '
C21
62
ELECTRONICS Australia, February 1995
familiarise yourself with the overall
operation of your new 'VMAC'. As
mentioned earlier, in a later article I
hope to bring you some ideas and
simple circuits for interfacing it with
'the real world'.
If it malfunctions
I truly hope you don't need to read
this, because fault-finding a project like
VMAC is not terribly easy!
First I have to stress that the chances
of a brand-new component being faulty
are very low. Assuming all the components are where they belong, the PCB
has no apparent defects, and the +5V
supply is appearing everywhere it
should be, you could check the following: If single recordings are getting
broken into multiple segments, and
other strange things are happening,
check that neither of the buttons is intermittent when pushed; this happened
on one of the prototypes ...
Are all socketed IC pins correctly
seated? Have you omitted to solder
any joints?
Are any of the ICs getting hot (apart
from ICl and 7 getting slightly warm)?
If yes, remove the power and recheck the
soldering around it very thoroughly! If
you do find a short, you might have to
replace the IC anyway...
If the Z86 is operating normally, at
switch-on its pin 1 will pulse to +5V for
about a second, then drop to OV again. If
it doesn't, is the crystal OK? (They just
hate being dropped!) The Z86 is very unC22
C24
470uF 16VW RB electro
10uF 25VW RB electro
semiconductors
0(2
01,2,3
IC1
IC2,3,4
IC5
IC6
IC7
LED1
1N4002 silicon power diode
BC548 NPNbipolar
transistor
7805 5V regulator
401414021 shift register .
Z86E0408 microcontroller*
1$01416/1.420
audio recorder
LM380N-14 audio amplifier
Red LED
li11scellaneous
PCB, 145 x 84mm, code 95vma2;
3.58MHz quartz c~tal (XTAL1); three-pin
header and jumper link (LK1); electret mfc
insert (MIC1); two NO
pushbuttons, clickless type (PB1,2); two 8way DIP switches (SW1 ,2); three
16-pin OIL sockets (IC2,3,4); 18-pin OIL
socket {1C5); 28-pin OIL socket (IC6);
18 x PCB terminal pins.
Optional parts
12V DC PCB mounting relay (200 ohm
coil; SPOT contacts); four three-way PCB
mounting terminal blocks, three two-way
PCB mounting terminal blocks.
likely to be faulty, unless it got zapped
by static electricity when you were installing it.
If IC6 records, indicated by the LED
illuminating, but there's no playback,
check the electret microphone's polarity.
If there's +2.5V and an audio signal on
IC6 pin 14 but it doesn't reach the outputs, is there a problem with mute transistor Q3? Its base voltage should go to
OV during playback. Did you connect
your speaker to the right pins?
If you touch the wiper connection of
VRl at mid-adjustment, you should hear
a slight buzz from the speaker. Check
IC7 if you don't.
A loss of chime, with a 'gap' in
playback where it should have been, suggests a problem around Q2 - is its emitter voltage about +2V?
If the VMAC isn't responding correctly or at all to its inputs and DIP switches,
check for a 9.5ms high/500us low
waveform on pin 9 of IC2, 3 and 4. With
the DIP switches set randomly, there
should be lOOHz bursts of high-frequency activity on pin 10 of those ICs, as
well as on IC2 pin 3.
A loud 'machine-gun' sound between
playback messages means the muting
transistor Q3 isn't functioning: check its
orientation and R19.
Unusual parts
If you 're not building the VMAC
from a kit and you 're looking for some
of the less common parts, Rockby
Electronics of PO Box 189 Huntingdale 3166, phone (03) 562-8559,
have· the 47k resistor packs RPl, 2 and
3 available as catalog number R5905,
and almost all of the other components,
too (at good prices).
Although they '11 no doubt be supplied
with kits, I'll be making sure the
preprogrammed Z86E0408 microcontrollers will also be available for the
foreseeable future from RCS Radio Pty
Ltd, of 651 Forest Rd Bexley 2207,
phone (02) 587-3491.
RCS will also have the PCBs available, as may other suppliers too.
(Don't you just hate projects becoming unbuildable or unmaintainable because some crucial component is 'no
longer available'?)
If things get really grim, contact EA
and ask them to put you in contact with
yours truly.
A final note of thanks. I'm indebted to
Graham Giulieri at R&D Electronics in
Melbourne, distributors for Zilog and
ISD products, for his enthu,siastic assistance on many occasions - without
which the VMAC would not exist.
Thanks, Graham! •:•
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Discovery Series' Construction Project:
SIMPLE FUNCTION GENERATOR
The third project in the new Discovery Series of learning kits from Dick Smith Electronics is a low
cost circuit using only two ICs, which can produce either sine, square or triangle waveforms at any
frequency between 10Hz and 100kHz. Designated as Cat. No. K-2802, the kit is available in DSE's
stores for only $16.95.
This project will allow you to build a
versatile, good quality function generator
at a surprisingly low cost. Both the
amplitude and frequency are voltage
controlled, which gives the experimenter
a variety of useful options. For example,
by using two of the circuits together, you
can produce an audio sweep generator or
amplitude modulated audio generator.
The circuit includes a voltage regulator
for good stability against varying supply
voltage and loading. A trimming facility
is provided for frequency alignment
when a calibrated dial is used.
The function generator can be powered
from a single 9V battery (not included)
for portability, or from any DC supply
between 8.5V and 15V. A 216-type 9V
battery 'snap' connector is provided.
To facilitate construction of the function generator, the printed circuit board
(PCB) has been designed to slide directly
into a zippy box such as the DSE Cat.
No. H-2851. Sockets for output and
modulation connections are not provided,
as these should be selected to suit the
particular application.
Construction
The complete function generator except for main controls, frequency band
capacitors and battery, is mounted on a
single printed board. To mount components, first look at the overlay
diagram to find the component name
- e.g., D3 - then look down the parts
list to find the value required. Some of
the components must be mounted with
a particular orientation, as described in
this section.
Begin construction by fitting the three
links to the PCB. The positions for these
are visible in the overlay diagram; one
goes 'lengthwise' between the positions
for resistors R4 and R8, while the other
two go 'crosswise' between R 12 and
trimpot VR 1.
Next install the resistors on the PCB.
There is a special expanded parts listing for the resistors, which shows the
colour code for the particular resistance
value required.
FLECTRONICS Australia, February 1995
The last band of the colour code is the
one furthest from the other bands. Resistors can be mounted in either direction,
but it is good practice to mount them
with their colour codes all in the same
direction, for ease of reading the values.
Next mount the diodes Dl-7 and ZDI.
These have to be mounted in the right
direction, with the stripe on the very end
of the diode corresponding to the striped
end shown on the overlay diagram.
Next mount the integrated circuits ICl
and IC2. CAUTION: The TLC555 IC
is a CMOS type, which is sensitive to
static electricity. Please observe the following precautions:
• Do not remove it from its protective foam until you are ready to install it.
•Avoid touching the pins with your
fingers.
• Make sure that your soldering iron is
properly earthed.
• Solder the power and earth pins of the
IC to the board first.
Mount the IC's in the board so that the
end with the notch in it is at the correct
end as shown on the overlay diagram.
A close up view of the function generator board with all of Its components fitted.
Use this photo In conjunct/on with the PCB overlay diagram as a guide when
you're assembling the project.
Next mount the transistors Ql and Q2. are supported by its contact lugs.
input. The output current is proportionPosition them so that the flat face faces
al to the product of the differential
the correct direction, again as on the How it works
input voltage (Vin= V(+) - V(-)) and
overlay. Do not push them down too
The circuit of the function generator is the amplifier bias current (labc) i.e. it
hard into the PCB, as this will spread the based on a type of integrated circuit multiplies Vin and labc. This facility alleads excessively and may damage the called an Operational Transconductance lows us to use direct voltage control of
internal connections.
Amplifier, or 'OTA' for short. The par- the amplifier. The maximum possible
Now mount the capacitors Cl and C6- ticular device used here is the National output current is equal to Iabc, so if the
12. Note that Cl, C7, C9-12 are Semiconductor LM13600. This device input is overdriven, the output is (+/electrolytic types which must be actually contains two OTA's, each with a )labc for(+/- )Vin.
There are two supply voltages used in
mounted in the right direction. The nega- Darlington buffer stage that can be extertive lead is marked on the side of the nally connected if required.
this circuit. One is an unregulated voltcapacitor with a negative (-) sign and
The main difference between an OTA age (Vcc) which appears on the cathode
the other lead, which is not marked, and the more common types of op- of D7, the reverse polarity protection
goes to the position that is marked with amps like the 741 is that the OTA diode, which is 0.6V less than the supply
a positive sign (+) on the overlay. The provides an output current that is voltage (e.g., 8.4V when using a 9V
two ceramic capacitors C6 and C8 can proportional to the differential input supply); the other is a regulated 6.7V
voltage, whereas the others provide an (Vref), which is supplied by a shunt
be mounted in either direction.
Then mount the two trimpots VRl output voltage that is proportional to regulator comprising Q2, ZD 1, D5-6 and
and VR3. It's a good idea to bend the differential input voltage.
R27-28. This regulator draws a constant
A feature of the OTA that makes it spe- current from the supply, which is split
the leads over after they are inserted
into the board, to give them a better cially suited for this application is an between the 6.8V zener diode ZDl and
mechanical hold - rather than just rely- extra input, called the amplifier bias the circuitry which operates from Vref
ing on the solder.
(which draws a fairly constant
The final step in completing
current).
The constant current
SPECIFICATIONS
the contruction is to make the
source reduces the effects of a
Sine, square, triangle
Output Waveforms
connections between the comvarying supply voltage on Vref.
0-SVp-p (load >250 ohms)
Output Level
pleted PCB assembly and the
There are basically three sec0-1Vp-p (load= 50 ohms)
various off-board components
tions to the main part of the cirOutput Impedance
<10 ohms at 1kHz
- the frequency band switch
(independent of level setting)
cuit. Firstly, there is an oscillator
Output Level Control
rinear voltage control
SWl, the waveform switch
using ICla and IC2, with variAM Input
AC coupled
SW2, the 'fine' frequency pot
able frequency control and a fremax input 1.4Vrms
VR2, the output amplitude pot
quency modulation input.
(for 5Vp-p 100% mod.)
VR4, the various input/output
Secondly, there is a triangle to
Output Frequency
10Hz-100kHz in four bands
connectors and the battery/
sinewave
converter using diodes
Output Frequency Control
linear voltage control
power supply. Note that
Dl-4 and resistors R21-26, and
FM Input
AC coupled
capacitors C2, C3, C4 and C5
a resistor network to equalise
max input 1.3Vrms
mount on the rear of SWl, and
the amplitudes of the three
lll-lllllHZ
11111-lllllllHz
lflll.JTllllE
1-llNfl:
lllDULATllll
m~
The schematic diagram for the function generator circuit.
Op-amp IC1a forms a controlled current source to charge
the capacitor selected by switch SW1.
'Ill
+ -
!!
This diagram shows the location of all of the parts on the
function generator PCB, as well as the connections to the
off-board components. Note that waveform switch SW2 is
actually a small slider type, not a rotary.
ELECTRONICS Australia, February 1995
65
'Discovery' Series Function Generator
waves}, and with the same amplitude as
the sine and triangle waves.
waveforms. Thirdly there is an amplifier the diodes are biased by the voltage
Looking now at the amplifier section,
using IClb and Ql, with level control divider made of R21, R22, R25 and R26 the selected sine, square or triangle wave
(the centre point of which also provides from SW2 - which has an amplitude of
and an amplitude m<Xlulation input.
The oscillator section itself consists of (1/2}Vref for biasing the two OTA's), about 0.7Vpk - is applied via attenuator
three parts. Firstly there is the OTA in so that they conduct at different volR9/Rl4 to the non-inverting input of the
ICla, which is not used as an amplifier tages. This has the effect of rounding off amplifier OTA at pin 14.
The level that appears at
but as a switched current source
this input has a peak amplitude
feeding the frequency band
PARTS LIST
determining capacitor (one of
of about 20mV. It has to be at
Resistors
this low level to minimize disC2-4, as selected by SWl).
(All 0.25W/5% metal film unless specified)
Secondly there is the ICla intortion without the use of feed4 Band1%
5 Band1%
ternal buffer, which is used to
back. This particular OTA
R1,2,8, 10 3.3k
Org Org Red Bm Org Org Blk Bm Bm
R3,23,24 6.•8k
Blu Gry Red Bm Blu Gry Blk Bm Bm
buffer the output of the OTA.
device actually has inbuilt
R4,11
4.7k
Yel Vio Red Brn Yel Vio Blk Bm Brn
Thirdly there is IC2, a 555
linearising diodes (shown as
R5,6,18
2.7k
Red Vio Red Bm Red Vio Blk Bm Brn
part of the OTA circuit symtimer IC, which is being used
R7
15k
Brn Grn Org Brn Bm Gm Blk Red Bm
bol}, which can be biased to
here as a comparator with input
R9
22k
Red Red Org Bm Red Red Blk Red Bm
hysteresis levels of (l/3)Vref
remove this particular nonR'f2
680 ohms Blu Gry Bm Bm Blu Gry Blk Blk Brn
R1a 14
390 ohms Org Wht em Brn Org Wht Blk Blk Bm
and (2/3)Vref.
linearity, but these were found
R15
18k
Bm Gry Org Bm Brn Gry Blk Red Bm
The way the oscillator works
to reduce the gain too much,
R16
27k
Red Vio Org Bm Red Vio Blk Red Bm
is as follows. When the voltage
and so were not used.
R19
68 ohms Blu Bry Blk Brn
Blu Gry Blk Gld Brn
across the selected capacitor is
In the absence of any
R17,20
10k
Brn Blk Org Bm Brn Blk Blk Red Bm
below (1/3}Vref, the output of
R21,26
1.5k
Bm Gm Red Brn Brn Gm Blk Bm Bm
amplitude modulation input,
R22,25
100 ohms Bm Blk Brn Bm
Brn Blk Blk Blk Bm
IC2 goes high (Vref), causing
the gain of the amplifier, and
R27
47 ohms Yel Vio Blk Bm
Yel Vio Blk Gld Bm
hence the output level, is
the OTA to charge the capacitor
R26
8.2k
Gry Red Red Bm Gry Red Blk Bm Brn
determined
by the control curwith a constant current equal to
VR1
2k
5mm vertical trimpot
Iabc. When the capacitor voltrent (labc) fed into pin 16 via
VR2,4
5k
16mm linear potentiometer
VR3
5k
5mm certlcal trimpot
age exceeds (2/3)Vref, the outRll, from VR4. R12 raises the
voltage at the bottom end of
put of IC2 goes low (OV)
Cllpacltors
C1,7
10uF
16/35VW RB electrolytic
causing the OTA to discharge
VR4 to about 0.8V, because
100V MKT (.0022, 222)
C2
2.2nF
this is about the minimum
the capacitor at the same rate.
100V MKT (.022, 223)
C3
22nF
voltage required to start Iabc
The resulting waveform across
1OOV MKT (220n, 224)
C4
0.22uF
flowing (the voltage at pin 16
the capacitor is a triangular
1OOVW RB electrolytic
CS
2.2uF
SOV ceramic (0.01uF, 103)
C6
10nF
wave, which is symmetrical
varies between about 0.8V and
C8
5.6pF
50Vceramic
1.4V, depending on current
about (l/2}Vref with a peak-to10VW RB electrolytic
C9
470UF
peak amplitude of (l/3}Vref.
and
temperature).
C10,11
100uF
16VW RB electrolytic
Amplitude modulation is
If there is no frequency
sovw RB electrolytic
C12
1uF
achieved by applying an
modulation applied, the
Semiconductors
AC
voltage
to
the
charge/discharge current from
01-6
1N4148or1N914 signal diode
07
1N4007 power diode
amplitude modulation input,
the output of the OTA is equal
ZD1
6.8V 400mW zener (1N957)
causing Iabc - and hence the
to the control current labc
01
BC549 NPN small signal BJT
amplifier gain - to vary in
which flows into pin 1 via R2,
02
BC559 PNP small signal BJT
proportion
to the modulation
from VR2.
IC1
LM13600 dual OTA
signal voltage.
Trimpots VRl and VR3 are
IC2
TLC555 CMOS timer
The load for the OTA is
used to set the upper and lower
Nllllt»llaneous
3-pole 3-position rotary switch (SW1); 2-pole three- position
formed by R15 and Rl6, with
. frequency limits respectively.
slide switch (SW2); 9V battery 'snap' cable; PCB, 43 x 88mm,
C8 added to remove overshoot
The values of VRl and VR3
code ZA1202; 30cm length of rainbow cable; solder, etc.
from the square wave. A single
were chosen to suit a one
resistor to ground could have
decade frequency range.
the triangle wave in a way that been used as a load, but the voltage
An AC voltage applied to the frequency modulation input causes Iabc, and produces a reasonably low distortion divider was used to raise the quiescent
hence the oscillator frequency, to vary in sinewave, at the common connection output voltage, compensating for the
side of the four diodes. This sinewave voltage drop introduced by the Darproportion to the signal voltage.
appears at the waveform selector switch lington buffer, and so increasing the
Next we'll take a look at the trimaximum available output voltage.
terminal SW2/2.
angle to sinewave converter. The bufThe output amplifier is a common colThe same triangle wave output is also
fered triangle wave from pin 8 of IC la is
lector stage using the IClb buffer, with a
applied via R8 to what is known as a fed to SW2/l via R7, which reduces the
lOmA constant current sink in the emitbreakpoint waveshaper network, consist- amplitude to that of the sinewave.
To provide a squarewave, the outter. This gives a peak output current
ing of Dl-4 and R21-26. The top half of
put of IC2, which alternates between capability of lOmA. Resistor R20 is
the network shapes the half of the triangle waveform that is higher than Vref and OV, is applied to the resistor added to keep C9 charged in the absence
of any other DC load, preventing large
(1/2}Vref, while the bottom half of the network R4-6. The output of this nettransients when the output of the funcnetworlc shapes the lower voltage half of work, which is applied to SW2/3, is a
squarewave which is symmetrical about tion generator is connected to a circuit
the triangle waveform.
under test+
The way the converter works is that (l/2}Vref (as are the triangle and sine
66
ELECTRONICS Australia, February 1995
AUSTRALIA
WIDE
1995 ELECTRONIC
COMPONENTS CATALOGUE
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These speakers are the very same as used by contractors
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50
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Doc.JH095
Construction Project:
NEW STEREO TV
SOUND RECEIVER • 2
In this second article describing our new stereo TV sound receiver, we cover its construction
and adjustment. There is very little setting up needed, and the alignment can be done quite well
using off-air signals.
by JIM ROWE
The complete sound receiver is
housed in one of the standard four-piece
plastic utility cases, measuring 250 x
190 x 80mm. These are stocked by
most of the major suppliers, and are
readily available. Inside the case, most
of the parts mount on a single printed
circuit board measuring 165 x 137mm,
with the code 95tvs 1.
Not mounted on the board are the
front panel controls, the 30V/500mA
power transformer, and the various
input and output connectors which are
all mounted on the rear panel. Also
mounted on the rear panel is the mains
fuseholder, and the Tune/Normal AFCdefeat switch SW3.
Although the six channel tuning
preset pots RVl-6 are mounted on the
PCB, they are located in the centre of
the rear edge, so that they can be adjusted easily via an elongated hole in
the rear panel.
This can be seen in the 'rear view'
photo, which also shows the way that
the tuner module's antenna input is
similarly accessible via a larger round
A view inside the receiver case, showing many of the components. The two modules are visible at lower right, and the
author's custom-made heatsink at upper left.
68
ELECTRONICS Australia, February 1995
A general view inside the case, showing where all the main parts are located.
clearance hole in the lower left-hand
comer of the panel.
The other connectors on the rear
panel are a group of six RCA- type
audio sockets for the various audio outputs, a BNC socket for the composite
video output, and a standard IEC panelmounting plug for the mains input.
On the front panel, the neon-illuminated mains rocker switch is fitted
at the left-hand end (looking from the
front), with the three main operating
controls to its right. First along is the
volume
control,
then
the
Mono/Stereo/Bilingual l/Bilingual2
switch SW2, and. finally the channel
selector switch SWI.
Inside the case, the power transformer
is mounted securely on a small earthed
aluminium plate, for safety. The plate
measures 110 x 45mm, and is cut from
Imm-thick aluminium sheet. In turn the
plate is attached to the bottom of the
case, alongside the main PCB. Note that
the transformer is mounted on the plate
at a small angle, to minimise the
amount of leakage flux reaching the
audio ICs on the board while still clearing the nearby case fastening pillar.
stall possible future problems due to
minor changes in case dimensions or
pin spacing. (Manufacturers have been
known to make such changes!)
Each of the two modules is attached
to the top of the board via four PCB terminal pins, with one near each comer.
After soldering these to the copper
under the board in the usual way, each
pin is bent over above the board so that
they contact the side of the module, and
together locate it in the right position.
Then using a reasonably high-powered
soldering iron, each pin is quickly
soldered to the module case.
Because the two modules are the
largest 'components' mounted on the
board, it's probably best to mount them
·in this way first, before fitting anything
else. This stage is completed by connecting each terminal pin of the two
modules to the corresponding PCB pad
below it, using a short length of tinned
copper wire.
I bent each wire with a small loop at
. the top, to fit around the module pin,
and a straight 'tail' to go down through
the PCB hole. This let me solder both
joints without the wire links falling off
all the time ...
With the modules installed, I suggest
that your next step is to fit the rest of
the PCB terminal pins around the board.
There are quite a few of these, but
they're worth using because they make
it much easier to fit the various offboard connection wires.
Most of the pins are located along the
front edge of the board, for the frontpanel control connections, or along the
side near the power transformer for the
various audio outputs and AC power inputs. However there are also four pins
near the front of the IF module, for
the composite video output and
Tune/Normal switch connections, and
two rows of seven pins down near the
channel tuning preset pots at the
centre rear of the board, for the connections to the channel selector switch
sections SWla/b.
After the pins are fitted, it's probably
a good idea at this stage to fit the
various wire links as well. There are not
very many of these, but they're best
fitted early to prevent trouble later
should they be forgotten. There are two
near the front of the board (one near
coil L2, the other near U2), one near
the rear of the board (just to the rear
of preset pot RV7) and another just to
the rear of the centre of the board, near
R17 and R18.
PCB assembly
Moving now to the PCB itself, as you
can see from the internal photos the
tuner and IF modules are mounted on
their side at one end. This has been
done to simplify their mounting arrangements, and also in an attempt to fore-
All of the inputs and outputs are brought out to the rear panel, as you can see.
The six preset pots used for channel fine tuning are accessible via the oblong
hole in the lower centre of the panel.
ELECTRONICS Australia, February 1995
69
Stereo TV Sound Receiver - 2
In addition, there are six further links
fitted between the two rows of pins
used for the SW 1 connections, and used
to 'program' your receiver for the band
switching needed for the TV channels
in your area.
The link programming scheme is
quite straightforward. The board has an
array of 24 holes, arranged in six rows
of four and with each row used for
programming one of the receiver's six
preset channels 1-6.
All you have to do is decide which of
your local channels you want on each
position of SWl, and then determine
the band they're in (low VHF, high
VHF or UHF). Then you simply fit
each link accordingly, using the PCB
overlay as a guide.
Each of the links runs between the
hole in its row nearest the SWlb connection pins, and one of the three
other holes to its rear, according to the
band required.
An example will hopefully make this
clear. In my case, in Sydney, I wanted
to program the prototype receiver to
receive channels 2, 7, 9, 10, 28 and 31,
in that order. So the first link was fitted
for the low VHF band (first hole), the
next three for the high VHF band
(second hole), and the last two links for
the UHF band (furthest/rearmost hole).
Or if you like, in rows 1-6 I fitted a
single short link, three medium-length
links and two long links.
With the links all fitted, my suggestion is to fit all of the preset pots next.
The six 10-tum tuning pots RV 1-6 all
go in a row at the centre rear of the
board, with +28V adjustment pot RV7
just on the transformer side of the
channel programming links and the
stereo matrix balancing pot RV8
nearer the centre, just behind coil L4
(when it's fitted). You may need to enlarge the mounting holes for the two
latter pots in order to mount them correctly, as some types have· elongated
and/or 'cranked' pins.
Probably the fixed resistors are best
fitted next, along with the other lowprofile parts such as the zener, varicap
and power diodes. Needless to say it's
important to make sure you fit the right
components in each position, and also
that the diodes are fitted with the correct orientation as indicated on the
overlay diagram.
The smaller monolithic, ceramic,
MKT and solid tantalum capacitors are
best fitted next, followed by the larger
electrolytics - again taking care to fit
both of the latter polarised types with
the correct orientation as marked on
the overlay.
You might like to fit the small RF inductor L1 next, mounting it as close as
you can to the PCB without straining its
leads. Then the next step would be to
wind the three slug-tuned coils L2-L4,
using Fig.3 as a guide. Note that all
three of the coils consist of a single
winding, tightly wound in a single layer
and located near the 'base' end of the
former. In each case they're also connected to the two pins on the base that
are spaced further from the other two
(pins 5 and 6, in Fig.3).
Another point to watch is that the
36MHz coil L2 is fitted with a tuning
slug of F29 ferrite material, while coils
L3 and L4 need to have slugs from F16
material because they operate at
5.5/5.74MHz. If you inadvertently swap
the slugs, the coils won't tune correctly.
Generally F29 slugs look a slightly
lighter shade of grey compared with the
Fl 6 type - this may help if you get
them mixed up!
Once the coils are wound on and/or
slipped on the formers, you can bare the
ends and solder them into the correct
base 'pins' (actually hollow tubes) taking care not to get much solder on
Another view inside the case, this time showing the wiring to the front panel controls, In greater detail.
70
ELECTRONICS Australia, February 1995
Bm
(POWER)
This overall wiring diagram should clarify any aspects of the receiver's off-board
wiring not made clear by the photographs.
the outside of the pins, or you'll have
trouble mounting the completed coil
assembly into the board. Then you can
fit the shield can, bending over the
small lugs at the bottom if you wish
(it's not essential) before fitting each
coil into the board.
Don't forget to mount the 6-turn
coil in the L2 position, and the 10turn coils in the L3/L4 positions.
Otherwise you'll again end up with
strange problems later!
Again, you may need to enlarge the
PCB holes to accept the coil pins, as
these are around l .5mm in diameter.
The ceramic filters and SAW filter
can be fitted next. You can't confuse the
SAW filter with the other two, even
though they look rather simular. The
SAW filter has five pins, all at 0.1"
spacing, while the two filters have only
four - two at each end, with a 0.3" gap
in the centre. Fit SAWFl so that its
orientation paint spot is at the end
nearest RF inductor LL
The main thing to watch with the two
ceramic filters is that you fit the
5.74MHz unit to the CFl position,
nearer to the rear of the board, and the
5.50MHz unit to the CF2 position.
These filters seem to be symmetrical,
and not unduly critical regarding orientation; however according to the
manufacturer's data they should be
fitted with their numbered side towards
the rear of the board, in this case.
With the filters in place you're ready
for the last components to be added to
0
3 0
5 0
0 2
0
0
the board: transistor Q 1 and the integrated circuits Ul-8. The orientation
of each of these is shown on the PCB
overlay diagram; note that the transistor
is fitted with its orientation lug pointing
diagonally across the IF module. It
should be fitted with the body as close
to the PCB as possible, without strai.ning the leads. The four three-terminal
regulators U4, US, U6 and U8 are all
fitted with their heatsink tab side
towards the rear of the board. Positive
12V regulator U4 is the only one that
needs a heatsink. However this one
does need quite a respectable heatsink,
as it dissipates around two watts.
As the component spacing is a little
tight in this part of the board, it isn't
easy to fit any of the currently available
commercial heatsinks with a sufficiently low thermal resistance. I ended up
fashioning a suitable 'flag' type heatsink from a small scrap of lmm
aluminium sheet, as shown in Fig.4. It
attaches to the device in the usual way,
using a 3mm machine screw, star
lockwasher and nut (with the wider
'staggered lug' section above clearing
the electrolytic caps and other
regulators, and the narrower lower
section pointing to the rear of the
PCB). A small smear of thermally
conductive grease on the tab of the
regulator before fitting the heatsink
will help ensure effective cooling.
Your PCB assembly phase should
now be complete, and you can move to
the next stage of preparing the case
front and rear panels. If you 're building
the project from scratch, rather than
from a kit, your next operation may
therefore be to drill and cut the various
control/connector mounting holes in the
two panels.
Even if you 're assembling a kit, and
the main holes have already been
punched, you may want to add extra
niceties such as short 'blind' holes in
the inside of the front panel for the
locating spigots of the switches and pot,
l2 (F29 slug): 6 turns
0.4mm ECW, close wound,
between pins 5 and 6
4
l3 (F 16 slug): 10 turns
0.4mm ECW, close wound,
between pins 5 and 6
0 6
(Former and pins
viewed from above)
l4 (F16 slug): 10 turns
0.4mm ECW, close wound,
between pins 5 and 6
Fig.3: Winding details for the three adjustable coils used in the receiver.
aECTRONICS Australia, February 1995
71
Stereo TV Sound Receiver - 2
machine screws, star lockand a similar (but smaller) hole
on the inside of the rear panel
washers and nuts, and also attach the solder lug to the plate
for the spigot of the Tune/Norin the same way. Make sure
mal toggle switch SW3. Adding
that you tighten all three
these holes only takes a few
---\
' _....
.,
machine screws firmly, so they
minutes, and stops the controls
10
won't work loose.
from working loose and rotating
\- .......
''
Finally, mount the plate and
on their axes later...
'.
'
Once you've cut all of the
transformer assembly inside the
\
''
case bottom alongside the PCB,
holes in both panels, the cen!
\
as shown in the photos. You'll
trols and connectors can all
TABS ABENT UP AT 45 DEGREES
find again that with some cases,
be fitted in the usual way.
TABS BBENT DOWN AT 45 DEGREES
TABS CBENT UP AT 75 DEGREES
the pillars for the plate's centre
Then you 're ready for the
', ".
7.5
and front mounting screws will
final assembly.
All ROUND HOLES 3mm DIAMETER
"'-\
',
again be shorter than that at the
The completed PCB subasBOTH TRANSFORMER MOUNTING
rear, so you may need a pair of
sembly is mounted in the botPIATE (lEffi AND HEATSINK (ABOVE)
CUT FROM 1mm ALUMINIUM SHEET
3mm ID flat washers under
tom of the case in the position
'
'
27.5 ', __ -;1
these screws for packing.
shown in the photos, using
With both the PCB and transseven of the 3mm self-tapping
former plate in position, the
screws which come with the
front and rear panels can then
case. Note that PCB holes for
be
laid 'face down' near their
the three screws along the front
Flg.4: Here are the cutting and drilling details for the
final positions, and the various
of the board line up with
transformer mounting plate and regulator heatsink.
connections made between the
moulded mounting pillars which
Now is the time to make up the trans- PCB terminal pins and the controls,
are about 2mm shorter than many of the
others (including those for the rear four former mounting plate, again using connectors etc.
screws), in one of the readily-available Fig.4 as a guide for drilling the mountcases. If you have this type of case, use ing holes for the transformer itself and Mains wiring
Make sure that the 'active' and
a couple of small 3mm ID flat washers the earthing solder lug - as well as the
'neutral' mains wiring connections are
under the PCB at each screw hole, to three holes for mounting the plate inprevent the board from being strained side the case. Then you can attach the made in suitable wire with mains-rated
transformer to the plate using 3mm insulation, and that all of the soldered
when the screws are tightened.
..
'...
..
... .
.
..
..
.. .
...
\~/
" \Jr)"
As usual, here is the PCB
overlay diagram for the
receiver, showing the location and orientation of all
parts.
,
72
ELECTRONICS Australia, February 1995
joints and their lugs are fitted with reliable sleeving to prevent accidental
finger contact. Small diameter
heatshrink tubing is excellent for this.
The earth lug of the IEC connector is
wired directly to the solder lug on the
transformer mounting plate, using
mains-cable 'earth' wire with green/yellow colour coded insulation. The 'A'
lug of the connector is connected to the
end or axial connection lug of the
fuseholder, while the side lug of the
fuseholder connects to the end lug of
the mains switch which does NOT have
a wire joined to it and disappearing inside the switch.
This 'active' wiring is aJ.l made using
mains-cable wire with brown (or red)
insulation, and the transformer's
primary wire with the same colour insulation is wired to the CENTRE lug of
the mains switch (which does have a
wire disappearing inside the switch).
The 'N' lug of the IEC connector has
two wires connected to it, one of which
is the remaining blue transformer
primary wire. The other wire, with the
same colour insulation, runs to the
remaining END lug of the mains switch
(which again does have a wire disappearing into the switch body).
In addition to fitting insulating
sleeves over all of the mains wiring
connections, it's a good idea to use a
few nylon cable ties to bundle the wires
together securely for increased safety,
as shown in the photos. The idea of this
is that if one joint should fail, the other
wires will hold the wire in position and
prevent it from 'wandering around' and
possibly contacting the low-voltage circuitry with disastrous results.
On the secondary side of the transformer, another nylon cable tie can be
used to hold the secondary wires
together, to prevent damage if one of
the connections to the PCB should
come adrift. Keep these leads as short
as possible, with just enough length to
reach to their respective PCB pin
without any strain; excessive length will
only cause them to get in the way. The
unused 7.5V tap should be cut short and
fitted with an insulating sleeve, and if
possible bundled with the other wires
inside the nylon cable tie.
Multicolour 'ribbon' cable can be
used for the connections between the
PCB and the channel selector switch
SWl, the mode switch SW2 and the
Tune/Normal switch SW3 (on the rear
panel). The same wire can be used for
the connections between SW2 and the
volume control pot. However for the
remaining audio and video connections,
it's a good idea to use light-duty coax
or shielded audio cable. The various
connections should be fairly clear from
the photos and the wiring diagram.
Note that the shield braid of the six
leads connecting the PCB to the rear
panel audio sockets should be connected to signal earth at only one end of
each lead, to prevent the formation of
earth loops. I linked the earth lugs of all
six RCA sockets with a length of tinned
copper wire, and connected the audio
lead shields at this end only. The com-
Here Is the receiver PCB etching pattern, reproduced actual size for the benefit of those who wish to etch their own board.
ELECTRONICS Australia, February 1995
73
Stereo TV Sound Receiver - 2
moo audio socket earth is also connected to the earth of the BNC
video socket, and connects to the PCB earth via the shield braid
of the video lead - which is connected at each end, like the
leads between the PCB and the volume control.
After completing all of the connections, spend a few minutes
checking over your work to ensure that everything is according to
plan. Then you should be ready for the testing and alignment phase.
(0
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74
ELECTRONICS Australia, February 1995
Testing and alignment
For this operation, you'll need to connect the antenna input of the
receiver's tuner module to your TV antenna, perhaps via a splitter
unit so that your existing TV set still receives signals as well. You'll
also need to connect the R and L audio outputs to a suitable stereo
amplifier, so that you can monitor the audio, and also feed the
receiver's video output to either a vid~o monitor, to your TV's
direct video input if it has one, or via a VCR if it hasn't. (Monitoring the picture makes tuning the sound receiver much easier.)
Before applying the power, turn the volume control fully anticlockwise and the mode switch to Mono. Also tum preset pot RV7
to the fully anticlockwise position, and RV6 to its centre position.
Then switch on the power, and with your DMM or multimeter
quickly check the voltages at the output of the bridge rectifier. You
should find about +21 V at the cathode (band) end of 03 or 06, and
-21 V at the anode end of D4 or 05. These voltages are relative to
PCB ground, of course - you can use the case of either the tuner
or IF modules as a convenient ground for your meter.
If these basic voltages seem OK, measure the voltage at the
banded end of zener diode 09; it should measure very close to
+ 33V. Then check the regulator output voltages, at pin 4 of either
U2 or U3 (+12V), pin 11 of the same chips (-12V), the wire link on
the PCB near R17 and R18 (+9V), and pin 19 of Ul (+5V). Take
care when you're measuring the voltages on IC pins, by the way; if
the test probe should slip off the pin, it can cause short circuits and
possible damage...
Should any of these voltages be absent, or significantly different
from the expected value, switch off the power immediately and
check for wiring mistakes - reversed diodes, etc. Needless to say,
you'll need to fix any problems before proceeding.
Assuming that things are fine this far, now try measuring the voltage on the wire link just to the rear of RV7, near Rl4. It will
probably measure around +24V, and the idea is to adjust RV7 with a
small screwdriver until the voltage rises to slightly over +28V. This
completes the receiver's basic DC checkout and setting up phase.
It's unlikely that you'll be seeing any pictures on the monitor at
this stage, or hearing anything other than noise if you tum up the
receiver's volume control. The ii.ext step is therefore to set up the
preset tuning. To do this move the rear panel Tune/Normal switch
SW3 to its 'Tune' position, if it isn't already in that position, and set
the channel selector switch SWl to position 1. Then with the
volume control turned clockwise to let you hear things as well as
see them on the monitor, slowly tum preset pot RVI until you can
at least get a clear picture for the station you want to receive on
setting 1. The correct tuning position is where you get a clean, sharp
picture, just before it starts breaking up with sound information.
When you believe you're at the right spot, try flicking SW3 briefly to the 'Normal' position. If the picture doesn't change, or changes only slightly, you are correctly tuned; otherwise you may have
to switch back to 'Tune' and try again.
(If you have trouble getting a good picture at the point where the
AFC results in stable tuning, you may need to make a slight adjustment to the tuner module's IF tuning slug. This is the s~ slug
accessible via the hole just near the IF OUT pin; it's very small, so
you'll need a very small ceramic or plastic alignment tool. Since it's
also risky to adjust it without instruments, be cautious and note
carefully the direction you've turned it,
and how far - so you can restore it to
the original setting if necessary.)
Once your first channel is correctly
tuned, change SWl to position 2 and
tune in the next station using the same
procedure. Then tune the other channels
in exactly the same way, doing all of
your tuning with SW3 in the 'Tune' position, and just flicking it back to the
'Normal' position to check each setting.
With all six channels set up in this
way, the last tuning step is to switch
SW3 back to the 'Nonnal' position, and
leave it there.
Sound alignment
Now you should be ready to align
the sound coils. This is not unduly difficult, and you should be able to do it
quite quickly. Frrst of all, turn SWl to
any of your local channels. Then turn up
the volume; probably most of what
you'll hear will be noise, but there will
probably be a small amount of
programme sound.
'.Now, using a suitable plastic or
ceramic alignment tool, slowly adjust the
tuning slug of 36MHz coil L2 in one
direction and then the other, until you
hear the noise level reducing, and the
sound signal increasing. Whichever
direction achieves this is the correct
direction to keep turning, until you reach
the optimum setting - where the noise
will pass through a broad null, and the
signal through a broad peak. (You may
need turn back the volwne control as you
proceed, to prevent overloading your
amplifier or your ears.)
When this optimum setting is found,
L2 is correctly set and you can turn your
attention to L3, the 5.50MHz coil. Here
again, it's basically just a matter of adjusting the slug in L3 until you get the
loudest undistorted sound, and the minimwn background noise. As the exact optimum setting can be a little tricky to
find, try deliberately turning the slug to
either side, until you hear the noise increase again each time. Then note how
far you've turned between the two 'noise
just audible' settings, and split the difference to locate the optimwn point.
With L2 and L3 both set up, your final
step is to set up IA. This is done in virtually the same way as L3, but with
mode switch SW2 set to the 'Bilingual2'
position so you're listening this time to
the signal from the 5.74MHz subcarrier.
It will also be necessary to make sure
you're tuned to a stereo station; otherwise there won't be any 5.74MHz sound
signal to peak up on!
Other than that, it's again just a matter
of adjusting the slug in IA until you get
Alternative IF module,
SAW filter
After our first article describing this
project had been printed, we learned that
the Hwa Un HL-PIF·36MC05 IF module
specified may have been discontinued by
the manufacturer. However an alternative
module is available: the HL-PIF-38MC02,
which appears to differ mainly in that Its
video IF is 38.9MHz, rather than
36.875MHz.
Although we have not had the opportunity to test this altemative IF module,
it should be possible to use it providing
the SAW filter used in the receiver's
sound channel is also changed, to a
Murata SAF38.9MVB70Z. As the type
number suggests, this filter is again
designed for 38.9MHz, and Is in fact
specifically designed for quasi-split
sound.
As far as we can see. no other component changes should be needed to use
these alternative parts. However in view
of the move in Intermediate frequency,
you will probably need to adjust the IF
output tuning slug in the tuner module, to
achieve optimum picture and sound
quality. Take care, though; adjusting this
slug without instruments is risky, so
make a careful note of the direction
you tum it (anticlockwise would be correct), and how far - so you can restore it
if you strike trouble.
the loudest undistorted· sound, and the
minimwn background noise.
Turning mode switch SW2 now to the
'Stereo' position shoUid at last result in
full stereo sound to emerge from your
hifi system speakers, and your receiver is
very close to finished. The only remaining adjustment is the setting for RV9, the
stereo matrix balancing pot.
This is not a critical adjustment, and in
many cases the initial 'halfway' setting
of this pot is likely to be fine. However if
you want to set it up accurately, the
easiest way is to monitor the 'L-R'
audio output with one channel of your
amplifier, while viewing a programme
with an essentially 'front centre' mono
source, in a relatively 'dead' environment - someone giving the news, for
example. The idea is to adjust RV9 for
minimum output from the L-R channel.
With this adjustment done, your Stereo
TV Sound Receiver should be complete.
All that remains is to screw the top on
the case, and settle down to enjoy yourself watching TV with the added dimension of stereo sound.
Of course if you wish to take advantage of the Receiver's L-R, L+R and
subwoofer outputs, for a low cost but
quite impressive 'surround sound' effect,
so much the better. You'll just need a few
more amplifier channels, to handle the
extra signals. I can recommend Rob
Evans' little Shoestring Amplifier for this
- it fills the bill very nicely. +
YOU CAN
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Name: _ _ _ _ _ _ _ _ _ __
~
Address: _ _ _ _ _ _ _ _ _ __
---------
P'dOde:__
Phone:_ _ _ _ _ _ _ _ _ _ _
ACN 002 174 478
~
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a:
W
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<(
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L---~~-----------------------~
ELECTRONICS Australia, February 1995
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Circuit & Design Ideas
Interesting circuit i?eas from readers and technical literature. While this mat.e~i~I has be~n checked as far as possible for feasibility, the circuits
have not been built and tested by us. We therefore cannot accept respons1b1hty, enter into correspondence or provide further information.
Dual polarity
supply
Vee
I recently needed a dual-rail power
supply for a low power circuit in a car. I
decided not to use an inverting switchmode power supply as it was far too
complex and expensive for the task.
The final design that I came up with
was a special type of series regulator
that is able to both source and sink current, while providing an output that is
exactly halfway between the power
supply rails.
The circuit is relatively simple. A
voltage divider is used to provide two
R1
B.2k
CJ
470µFl16V
01
TIP31
C1
R2
68
+
1000µF
03
TIP32
RJ
C4
B.2k
470µF/16V
+5
1-1 1-1 1-1 1~1
~Ir---'-! 1:1 1:1 1:1 1:1
:,~ !"'--:~.-J\1\1\r----!..I
3,8
3,8
LATCH
E
3.8
__.'IN\r--ff
(IC5a, pin 3)
as
BC337
CLOCK ~--------'
(S1a com)
RESET - - - - - - - - - - - - - - '
(IC5b, pin 11)
07
BC337
LED display driver
This circuit was designed to replace
the 74C926 IC in the Tacho/Dwell
Meter featured in EA October 1980.
This IC now costs around $20, while the
ICs in this circuit cost about $5.
The 4553 has all the counters, multiplexers, latches and BCD outputs to
drive three digits.
The original circuit has four digits,
but the least significant display
(LSD) shows zero all the time anyway.
This is achieved in the alternative circuit by connecting segments A to F of
the LSD to the +5V rail, via a 10 ohm
current limiting resistor, and multiplexing the display in parallel with the
second display.
80
ELECTRONICS Australia, February 1995
The 4553 needs a low on the latch
enable line (pin 10), where the 74C926
requires a high. Transistor Ql and its associated resistors provide the necessary
inversion. The clock and reset lines
don't need to be altered.
Capacitor Cl sets the multiplexing
frequency. The 4511 decodes the BCD
output from IC2 to the seven-segment
output needed by the displays. Its output
stage can drive the displays directly, via
27-ohm current limiting resistors. Each
display is multiplexed by the outputs DO
to D2 of the 4553 and their associated
transistors, which are connected in a
Darlington arrangement.
G. Moore,
Albion Park, NSW.
$25
voltages, each slightly different to the
midpoint voltage (Vcc/2).
These voltages are fed to the non-inverting inputs of two op-amps, which
are arranged in a voltage follower configuration. This means that the emitter
voltage of the power transistors (Ql and
Q3) will be virtually the same as the
voltage on the non-inverting input of the
op-amp they are connected to.
Therefore, if the link between the
emitter of Ql and the emitter of Q3 was
cut, there would be a voltage slightly
higher than Vcc/2 at the emitter of Q3,
with the emitter voltage of Q 1 slightly
lower. This has been done to prevent the
power transistors forming a possible
short-circuit between the supply rails, as
for these emitter voltages, the polarity
of the transistors will prevent any current flowing.
This circuit has many applications,
such as a basic dual-rail laboratory
power supply. The power rating of the
circuit can be increased by using
2N3055/MJ2955 transistors rather than
the type shown.
A fuse should be connected in series
with the circuit if it is being powered
from a car battery or an unprotected DC
power supply. The maximum supply
voltage is 30V.
Peter Tree,
Palm Beach, Qld.
$40
If you have· a great new idea for a
circuit, why not let us know. Send your
diagram and note.s to .The Editor,
Electronics Australia; PO Box 199,
Alexandria, NSW 2015.
"
-----·--------
-------------
----
DTMF decoder
This circuit will decode a string of
DTMF tones and store them in memory,
allowing you to index through the
memory and display each of the DTMF
'digits' when you wish.
It is a hardware-only design, and is
therefore less complex than the various
microprocessor-based designs that have
appeared in overseas electronics
magazines.
IC 1 is a Motorola 145436 DTMF
decoder (available from Altronics),
which produces a BCD weighted output for the correct tone pair it sees at
its input.
As well, it produces a 'data available'
(DV) level change at pin 12. Most
DTMF series of tones are non-contiguous, which means each DTMF is
separated by a no-signal pause (usually
60ms each), and therefore the pulsing
signal at pin 12 (DV) can be used as a
strobe to load the BCD digit into the
6116 RAM.
IC5 is a quad Schmitt trigger NAND
gate, with IC5b and its associated RC
network used to form an inverted write
pulse for IC2. The 'data available' pulse
is also used to increment a simple address register, via IC5a and IC5c, to
IC3, a CMOS ripple counter.
The address presented to IC2 is then
ready for the next DTMF decode. The
output display has been kept simple
1
Vin 20-BOOmV
AUDIO
IN
IC1
•5
10k
145438
EN
1M
16
IC3
<I>
4040
3
13
P-----.---=
j 03
1
3
A7t-'--1~
07
f ' " - - - + - + - - - " " - f 1 1 02
~-+_,_.,___1__,o 01
AS J
2 05
A4 4
3 04
A3 5
5 Q3
A2. 8
6 Q2
AS 2
-~-,..., _':~r---H--+1~---"-19 00
IC2
=
•5
6116
4
Q6
10k
=
7- - ' - I
A1t'AD e
=
and consists of a 7404 inverter (IC4)
driving four LEDs. Each LED has a binary weighting (8, 4, 2 and I) as
the output is in BCD form. Otherwise,, a BCD to 7-segment decoder/display driver circuit is needed.
To use the device, I recommend that
DTMF tones (from a scanner, etc) are
first recorded on tape. Set the
read/write switch to 'write' and push
the reset button, then feed the audio
signal from the tape into the circuit.
Piezo screamer
r
=
ICI will then decode and self-clock
each sequential DTMF decode into IC2,
starting at address 0000.
To read the information, press the
reset button and then index through
the memory using the address pushbutton (debounced by IC5c).
The display will show each digit in
order. Note that the circuit operates
from a 5V regulated DC supply.
Frank Hughes,
Mt Hawthorn, WA.
$45
SW1
This circuit is an oscillator based around a lk to eight
ohm audio transformer, and can be built onto a piece of PCB
measuring around 1.5 x l.5cm.
It produces an intense whistle and is quite unbearable in
close range. It has numerous applications, and I have used it
as an indicator and an alarm.
Capacitor Cl is selected according to the required output
frequency. Typical values range from 27nF to 0.22uF. A
O. luF capacitor is very effective.
Andrew Merrick,
$20
Northbridge, NSW.
C1
see text
~
I
_,__
9V
TRF radio
This simple circuit is a TRF broadcast
band radio receiver. It is cheap and easy
to build and doesn't need any test gear
for alignment.
The circuit uses an MK484 IC, a
IO-transistor device that includes an
RF amplifier, active detector and
AGC. The LM386 has enough gain
and output drive capability to drive
an eight-ohm speaker.
It operates at full gain, achieved by
the connection of C3 to pins 1 and 8.
The rod antenna should be
mounted away from the LM386, to
R3 6.8k
D---9
+9V
R1
100k
IC1
MK484
Bohm
speaker
prevent feedback. With no input signal, the. circuit draws about 6mA
from a 9V battery.
This is a simple circuit for beginners.
Robert Milne, ·
Moonah, Tas.
$30
ELECTRONICS Australia, February 1995
81
Mini Construction Project:
AUTOMATIC HOUSE NUMBER
How would you like your house number to automatically glow at night, so that visitors could easily
find the correct address? This simple little project will let you be the first in your street to provide your
house with this up-market feature.
by ANDREW PALMER
Many of the homes in affluent areas
of the USA and Europe are now sporting address numbers with lighting
which comes on automatically at
nightfall. It's a very nice feature, much
appreciated by any first-time visitor
trying to find your place in the dark.
Of course you could achieve this
result by using one of those light-activated switches, in conjunction with an
outdoor spotlight directed at your
present house number. But this would
be a bit messy, and in any case most
outdoor spotlights consume around
150 watts - hardly the sort of thing
you'd want to have running all night
every night, in this era of energy
conservation!
This little project provides a much
more elegant and energy-efficient solution. It lets you present your house
number using 'jumbo' seven-segment
LED displays, with digits 57mm high
- large enough to be read clearly from
across the street, unless there's a very
thick fog indeed ..
The LED displays are very brignt, but
at the same time they 're highly efficient, so that the energy consumption is
typically only a couple of watts. But the
The plctutes at right and lower right
show how the house number appears
during the day, and then· during the
night. The 'Jumbo' llt!WM aeg_,.t LED
displays have digits 51mm high;. and
glow vel}' brightly for hlglf vlslb/llly. A
view of the PCB module Is shown
below, with the light sensing LDR
visible at lower Wt.
82
ELECTRONICS Australia, February 1995
really nice thing about the project is
that the LED displays are powered
using a circuit controlled by a light-dependent resistor (LDR), so that the LED
current and brightness is automatically
varied according to the ambient lighting
level.
During the day, when there's no need
for them to glow at all, the circuit effectively switches off the current completely. But as dusk falls and it gets
darker, the LDR automatically senses
this and current is gradually increased
to the LEDs, so by the time it's dark
they're glowing at full brightness. Then
This view of the rear of the display PCB shows how the small number of components used In the power supply and current
control circuit are mounted on the back of the board 'surface mount' fashion. The heatslnk tab of the LM7805 regulator is
mounted against a copper area on the board, to assist In keeping It cool.
as the new day dawns and the sun rises,
the WR quietly throttles back the current again.
In short, your house number will
glow when it should, and not during the
day. And it will do this automatically,
without you having to lift a finger or
remember to switch anything on or off.
Of course during the day, with standard seven-segment LED displays you'd
normally be able to see all of the segments, so that your daytime house number would become '888'. However this
is easily fixed, by using black paint to
make the unwanted segments just as
dark during the day as they are at night.
01-04
4x 1N4001
Before we look at the circuit, I should
note that this project has been
developed by Paris Radio Electronics,
who can supply all of the special parts
it involves - the jumbo LED displays,
the LDR, the PC board and very nice
metal-and-glass case shown in the main
photos. For those who don't have the
time to build up their own unit, PRE
can also supply it to order fully assembled at tested. More about these options later.
The circuit
As you can see from the schematic,
the circuit for the automatic house numP1
BC337
LM7805
2
C1 47e>1F
25
4
C2
1,5
1nF
AC
12-18V
her unit is quite straightforward. The
power to run the LEDs normally
derived from an AC 'plug pack' supply,
delivering between 12V and 18V AC.
(In areas away from an AC supply, you
could use a 12V battery instead.)
The incoming supply is first passed
through a full-wave bridge rectifier
formed by diodes D 1-4, with capacitor
C 1 used for smoothing the resulting
DC. An LM7805 three-terminal
regulator is then used to produce a
regulated voltage Pl of around 8V DC,
for the.,LED display control transistors
Tl and T2.
Note that to provide the regulated 8V
ANODE
R4
MKY-54C348
3-500k.Q
B· f3 B 8
e
2
*Typically 820 ohms -- see text
Incoming unregulated AC from a plug pack or DC from a battery Is used to produce a regulated eight volt supply by the
LM7805 regulator, In con/unction with resistors R1 and R2. Transistors T1 and T2 are then used to control the current fed
to the LED displays, with LOR R4 control/Ing the Input voltage to transistor T1.
ELECTRONICS Australia, February 1995
83
HI--FI
An Introduction
High quality sound
reproduction isn't really all
that hard to \lnderstand,
despite the jargon that tends
to surround it.
In our new publication we
explain how the equipment
works, what the jargon
means, how to select the
right equipment for your system and then how to set it up
to get the best results.
The author is Neville Williams, formerly Editor-inChief
of
Electronics
Australia, and one of the best
known and widely respected
authorities on high fidelity.
Mr.Williams has tested and
written about countless
pieces of hi-fi .equipment,
over a 50 year period; there
isn't much he doesn't understand about hi-fi!
In this book, he explains all
about high quality sound
systems, starting with human
hearing and moving all the
way through to compact
discs and the latest technolo~
Available from your news
agent or by mail order.
Price $4.95 plus $2 p&p,
when ordered by mail.
The Book Shop,
Federal Publishing
Company,
P.O. Box 199,
Alexandria, NSW
2015
84
ELECTRONICS Australia, February 1995
Automatic House Numbers
PARTS LIST
Semiconductors
01-4
T1
T2
LD1-3
U1
1N4001 power diode
BC337 NPN transistor
MJ613 NPN power transistor
Jumbo 7-segment LED display
LM7805 5V regulator, T0·220
Resistors
R1 •
R2
R3
R4
820 ohms 0.25W 1% metal film
330 ohms 0.25W 1o/o metal film
10k linear preset pot
MKY-54C348 LOR
Capacitors
C1
C2
470uF 16VW RB electrolytic
1nF ceramic
lllSCflllaneous
PCB, 170 x 90mm (see text); 12V
AC/300mA ptug pack supply; enamel or
brass finished case with glass window,
as desired.
supply, the 7805 regulator is
'bootstrapped' via resistors Rl and R2.
The value of R 1 can be varied over a
small range to adjust the maximum current (and hence brightness) fed to the
LED displays.
For most users, the best value for Rl
will be 820 ohms as this results in a
regulated voltage Pl of around 8.25V.
Changing Rl to 750 ohms will give a
voltage of around 8.4V and higher
brightness, while increasing it to lk
will reduce the voltage to around
7 .85V and reduce the maximum
brightness.
Tl and T2 are connected as a Darlington pair, used here as a high current-gain emitter follower. Tl is a
BC337 small-signal NPN device,
while T2 is an MJ613 plastic package
.powerNPN.
The base of Tl is fed from preset
pot R3, which is connected in series
with R4 across the 8V supply rails. R4
is the LOR, whose resistance varies
from around 500k in the dark down to
around 3k when it's brightly illuminated. R3 is provided so that you
can set the circuit's 'threshold' - i.e.,
the ambient lighting level where the
LEDs begin to glow.
As you can see, the voltage fed to
the base of Tl will vary according to
the light falling on the LOR, and this
is how we achieve control over the
current through the LED displays.
The displays are of the commonanode type, with all of their anodes
connected to the emitter of T2. The
PCB has all segment cathodes for
each of the LED displays brought out
to pads, making it easy to 'program'
'each display for the digits you need,
merely by linking the appropriate pads
to the negative supply rail.
Construction
As you can see from the photos, the
complete unit is based on a PC board
measuring 170 x 90mm. Three of the
jumbo LED displays fit on the front of
the board, along with the LOR (at lower
front). Hence the unit as shown can
cope with any simple numeral-only
house number from 'l' to '999', plus
many composite numbers like '27a',
'42b' or '83c'.
For those who must have a four-digit
or three-digit-plus-letter number, we understand that a four-display version of
the PCB will be available from PRE.
The small number of components
needed for the LED brightness control
circuit are fitted to the rear of the
PCB in 'surface mount' fashion, as
you can see. The heatsink tabs of T2
and the 7805 regulator are simply laid
in contact with the PCB copper, and
this provides adequate heatsinking.
It all makes a compact and tidy as. sembly, and as you can see PRE has
available a very nice matching case,
for fitting to a suitable position on
your front porch or wherever.
The case is available in two versions, by the way - one finished in
white powder-coat enamel and the
other in brass. Both versions are solidly made and include a glass protective
window for the displays.
Getting the parts
As noted earlier, all of the key components needed for this project are
available from Paris Radio
Electronics. The special jumbo LED
displays are priced at $12 each, while
the PCB and LOR are available for a
further $12 plus tax. The enamelled
version of the case is priced at $40,
while the brass version is $60. All of
these prices are plus tax (21 %) where
applicable, and do not include
postage. Needless to say, the rest of
the parts are quite standard, and you
should be able to pick them up from
many suppliers.
If you prefer to buy the complete
unit as pictured assembled and tested,
the cost is $129 including tax for the
enamelled case version, or $149 for
the brass version.
For further information, contact
Paris Radio Electronics at 161 Bunnerong Road, Kingsford 2032; phone
(02) 344 9111. +
SHORTWAVE
L1srEN1NG ~;:~.,.
Arth"'
MBE
More interesting summer listening
This month we cover many more countries
which have broadcasts in English, and beam
their transmissions to Australia and New
Zealand.
BULGARIA: Radio Bulgaria, Sofia broadcasts
to Australia at 1000 - 1100 on l 2,040kHz and
to North America at 0500 - 0600 on 7335 and
9700kHz. These are the best received transmissions in this area, and the use of 733SkHz
is interesting because that is close to Canadian
Time Signal Station CHU, on 7333kHz.
CANADA:
Radio
Canada
International,
Montreal broadcasts at 0200 - 0259 on 6120,
975SkHz; at 0300 - 0359 on 9755; at 0400 0429 on 9505, 9670kHz; at 0600 - 0629 Monday - Friday on 6050, 6150, 9760, ll ,905kHz;
and at 2100 - 2220 on 11,945, 13,650,
13,690, 15, 140, 15,325 and 17,820kHz.
CUBA: Radio Havana, Cuba has announced a
new English schedule, at 2100 - 2200UTC to
Europe on l 1,720kHz; to Eastern North
America at 0100 - 0500 on 6000kHz; and to
Western America at 0500 - 0700 on 9820kHz.
There is an SSB test on 9835kHz using a power
of 30kW and it is in parallel with the broadcast
on 9820kHz.
ECUADOR: HCJB, Quito has broadcasts to the
South Pacific at 0700 - 1100 on 613SkHz,
replacing 11,925 and 9745kHz; to North
America on 12,005 at 0400; and at 0430 the
station drops 9745 but continues on
12,00SkHz as well as SSB on 21,455 and
17,490kHz.
FRANCE: Radio France International broadcasts to Oceania at 1400 - 1500 on 7110,
12,030 and 15,40SkHz; and to North America
at 1200 - 1300 on 11,615, 13,625, 15,365,
15,515, 15,530 and 17,575kHz. The station
broadcasts in French to Australia at 1030 1130 on 1l ,700kHz.
HUNGARY: Radio Budapest has broadcasts at
2000 - 2030 and 2200 - 2230 on 3995, 6110
and 7220kHz; at 0200 - 0230 on 6025, 7220,
9835kHz; and at 0330 - 0400 on 5970, 7220
and 983SkHz.
ISRAEL: Transmissions have been retimed and
the best two broadcasts in this area are at 0500
- 0515 on 7465, 9435, 17,545kHz; and at
2000 - 2030 on 7405, 7465, 9435, 11,603 and
17,575kHz.
KOREA: Radio Korea is received in English at
1130 - 1200UTC on 9650kHz, the transmissions being relayed by Radio Canada International. Radio Korea also broadcasts in English
at 0100 - 0200 on 7500 and l S,575kHz; and
at 2100 - 2200 on 15,575kHz.
PALAU: Palau has formally proclaimed independence and was the last United Nations
Trust Territory in the Pacific. Palau wiff con-
tinue to receive American aid and it has a
Treaty to retain the base for 50 years. The station can be heard on shortwave when KHBN is
heard at 9830kHz at 0900UTC, with English
announcements and programmes in Chinese.
RUSSIA: Now known as the Voice of Russia
World Service, Moscow, the schedule for listeners in Australia and New Zealand is extensive but the main times of listening are as
follows: at 0600 - 0700 on 15,320, 17,610,
21,790kHz; at 0900 - 1000 on. 9550, 9800,
11,675, 11,710kHz; also at 1100- 1200, 2030
- 2100UTC on 9780 and 12,015kHz.
SPAIN: Radio Exterior de Espana, Madrid is
well received in the transmission at 0500 0600UTC on 9540kHz. The broadcasts include on Sunday a programme called Distant
Listening, of special interest to shortwave enthusiasts.
SWEDEN: Radio Sweden, Stockholm has a service in English to Asia and the Pacific at 1230 1300 on 1,3775, 15,120 and 15,240kHz; at
2300 - 2400 on 11 ,910 and from 01 30 - 0200
on 9895 and 1l ,695kHz.
SWITZERLAND: Swiss Radio International,
Berne has English broadcasts to the Pacific at
0900 - 0930 on 9885kHz, relayed via French
Guyana. The station also uses 13,685 and
17,51 SkHz, which are direct transmissions
from Switzerland.
THAILAND: Radio Thailand World Service has
dropped 9700kHz and 1900 - 2000UTC transmission in English is now on 11,855 and 2030
- 2045 to Australia and New Zealand is now
on 11,835kHz.
TURKEY: Ankara has broadcasts in English at
0300 - 0400 on 944SkHz; also at 2000 - 2100
on 9400; at 2200 - 2300 on 11,710 to Europe;
to the Middle East at 2200 - 2300 on 7185;
and to South West Asia at 1230 - 1300 on
9675kHz.
USA: WEWN, Birmingham, Alabama has an
extensive schedule but the best times for
reception in the South Pacific are at 0400 on
7425; at 0600 on 7425; and at 0800 on 7425
and 9350kHz.
WINB, PO Box 88, Red Lion, PA is using
12, l 60kHz up to its 2100 sign off. It then
moves to 11,91 SkHz. WINB is now operated
by new owners and has made some frequency
changes; in the past for many years they
. operated on the same channel, 15,lBSkHz.
WWCR: Nashville, T~nn., is using a frequency near the 60 metre tropical band. They are
on 506SkHz and have been noted at
0600UTC; this is the first time that a US station
has moved to such a low frequency.
Shortwave listeners have been concerned
that this may be a trend with the falling
sunspots, to move into a band which has been
traditionally only used by stations in the
tropics. WWCR is also using 12, l 60kHz from
21 OOUTC. They open on the frequency at
WINB closes.
YUGOSLAVIA: Radio Yugoslavia, Belgrade has
been noted in the European Service at 1930 2000 in English on 9720kHz with a fair signal,
while the other frequency of 6100 is blocked
by Deutsche Welle. The station has made
some changes to its English broadcasts: to
Australia at 1300 - 1400 on 11,86SkHz; at
1930 - 2000 to Europe-Africa on 6100,
9720kHz; at 2200 - 2230 to Europe on 6100,
6185kHz; to North America (except Sunday) at
0100 - 0130 on 6195 and 0200 - 0230UTC on
6190kHz.
France's new system
Radio France International has inaugurated
the first of a new generation of shortwave
transmitters and antennas, which according to
BBC Worldwide are of unconventional design.
Most shortwave broadcasting sites have a
large central building, which houses the
transmitters and with the antennas radiating
from it. This has been the practice since the
BBC's Empire Service transmitting station was
built at Daventry.
RFl's new SOOkW transmitters at Allouislssodun in central France are located in an underground bunker. Instead of feeding the signal
out to a large, complicated antenna farm
shared with other transmitters, each has its
own rotatable curtain antenna array immediately above the bunker.
This allows for a little more flexibility in
scheduling, because each transmitter has its
own dedicated antenna. Frequency engineers
no longer have to plan which transmitter can
be switched to which aerial throughout the day
and night. Because the antenna rotates, it can
be aligned to beam programmes in any direction in any time.
Voice of Peace
The Voice of Peace is a new transmission
from Addis Ababa, Ethiopia and is operated by
a group of European charitable organisations
who are promoting peace and reconciliation to
express humanitarian concerns for the Rwandan people. The broadcast is heard opening in
English at 0400UTC on 9560kHz, and is the
first indication of concern through radio for the
problems in Rwanda.
It is understood that the transmitter was
formerly that known as the Voice of the Gospel
and taken over the authorities when there was
a change of Government in Ethiopia, as a
propaganda outlet.
Deutsche Welle some years ago established a relay base at Kigali, the capital of
Rwanda. This consists of two 250kW transmitters. The first was installed in 1968 and
the second in 1989. During the height of the
Rwanda fighting the transmitters were off the
air, but are gradually being put back into service as electricity and communication is
being restored to the area. Rwanda itself had
its own internal domestic service, which was
carried on shortwave, and earlier last year
reception of l 5,340kHz was often reported in
the South Pacific. +
This item is contributed by Arthur Cushen, 212 Eam Street, lnvercargil/ New Zealand who would be pleased to supply additional information on medium and shortwave
Hstening. All times are quoted in UTC (GMT) which is 11 hours behind Australian Eastern Daylight Time and 13 hours behind NZ Daylight Time.
ELECTRONICS Australia, February 1995
85
*********************
•·lbOO l'l>rR SEC'll)R .\L:\R\I P\XEL it-
**
*
*·~
*
*
**
**********************..
Door Phone Intercom Speaker
This doorphone system gives you maximum
l••••••••r~~~~'
security by allowing you to talk to whoever is at the
front door without opening it.
The system includes an Indoor Station and a
weather proof Outdoor Annunciator Station. The
visitor presses the push button on the outside unit,
this activates the indoor station which sounds a
pleasant "ding dong". To speak with the visitor
press and hold the "operate/talk" button. For
listening, release the button. The visitor station
becomes hands free and incorporates an auto power switch to switch the unit off after 30 seconds.
Requires one 9V battery or use a 9VDC plugpack (Cat MP-3003 9VDC 150mA $10.95). Both units are
made from ABS plastic, there is a low battery warning light and the two units are connected with a 2 core
cable which is supplied (20 metres).
A quality low priced product that is user friendly and works well.
Cat. AM-4320
$3 2. 9 5
fP(]rn
rF©>~
BELLMATE 200
PASSIVE INFRA
RED
DETECTORS
The manufacturer was overstocked so
we have made a special deal - and
you save!!! 12 months warranty
Features and Specifications:
•Dual element pyroelectric sensor
•24 dual element detection zones in
three layers •Wide angle 90° multi
layer coverage •12 metre range
•Operation voltage 11 - 16V DC
•Current draw 20mA •Tamper proof
•LED indication •Relay output. N.C.
contacts. 220 for shorting protection
•Max rating 0.5A 24V DC resistive
•Colour white•Size 93 x 73 x 43mm
Cat. LA-5017
WAS$34.95
AM I FM POCKET
RADIO
This small radio has excellent tonal qualities for
its size. Its AM and FM has a tuning and volume
control, an earphone socket and a carry strap. It
takes 2 x AA batteries (not supplied) and
measures only 61(W) x 99(H) x 19(D)mm. Ideal
size for pockets, bags, glovebox, etc for listening
· to the races, while gardening etc.
Cat. AR-2220
$17 .95
1X1~U:-:V~JSURROUND SOUND
KIT
REFER SILICON CHIP MAGAZINE DECEMBER 1994
half that. You will have to assemble the kit though. The kit will give you
Jaycar are proud to announce the "KIT OF THE DECADE".
amazing cinema sound in your home. You will need a Hi Fi VCR or any other
An enormous amount of effort has gone into this project
source of a stereo soundtrack ie Stereo TV, Laser Disk, Cable or Satellite
by staff at both Jaycar and Silicon Chip.
signal and of course an amplifier for the centre and rear channels.
Up until now, if you want Dolby Pro Logic it will cost you
at least $500. Now you can have it for less than
..._*'-1...fll•
The kit is approved by Dolby
Laboratories (USA), and is the
only kit currently available in
the world for a Dolby Pro Logic
Surround Sound Decoder.
TOTAi.. ONl..Y $239.00
SHORT FORM KIT
PCB and all on board components*
including Dolby chips, switches,
potentiometers & RCA sockets.
Cat. KC-5175 ONLY $169 .50
New for 1995. There are many units on the
market that look similar to these, but before
buying please look at the features our have
that are probably not on the others, and these
others are probably more expensive!! We are
direct importing these, so there Is no
expensive middleman making his cut. Check
out our price!!
Units operate on the detecetion of body heat.
When the unit detects human movement
within Its field the floodlight switches on
automatically. After the fast detection of
movement It will operate for a preset time,
then switch off and rearm itself. Only
operates after dark.
flalltw;, •Attractive integrated design •1111° viewing angle •Range 1Oto 15
metres -Operates only after dark •LED walk test facility •PIR adjustable both
vertically and horizontally -Complete with Tungsten halogen lamps •Adjustable
sensitivity •Adjustable time on -Enclosed floodlight with plastic cover •Better than
our old PAR38 because they could be hit with a hammer and broken.
Specifications· •PIR • 28 segments with 3 levels •Range at 2.5m mounting height •
15° from vertical 12·15 metres •Test reports for compliance to BS4533 Part 101
(EN60598·1) •240VAC operation -Oimensions: 150 watt: 120(W) x 130(0) x
160(H)mm, 500 watt: (190(W) x 140(0) x 220(H)mm Total siz~
Soare Halogen Ughts avaUable
tSO watt• c.t SL-2728 '3.H
100 watt • c.t SL-2728 $4.H
150 Watt Cat. LA-5135
500 Watt Cat. LA-5138
$39.95
$49.95
liiiJiC£iiliii"Aclt"JA.ciC-GAME __ _
: Now you can take out your gambling
1frustrations without fear of losing your
: money, and have hours of fun. It sits in the
1 palm of your hand, colour backed LCD
: display, soft touch keys, music or music
1 mute, robust construction· so It can take
: the aggrevation of losing. Runs on 2xAA
1batteries (not supplied).
POKER
1Just like the real poker card machines in
: Clubs, Pubs etc.
l•Bet high or low •Double up as many times as you like •Bet from $1 to $100 I bet
1BLACKJACK • JUST LIKE THE REAL CASINO'S
split -Can have insurance like the dealer •If you have never played Blackjack
1this game will teach you how to play. For example • "word" prompts appear when
other options are available (Split, Double your bet and insurance to the gambler).
1Betfrom$1 to$100perbet.
I
I-can
l
•cat.QNl-7360
$l7 95
•
~-----------------------------------------~
TELEPHONE CABLE SLASHED*
1
This cable Is the standard flat ~
type Ivory coloured telephone
cable. It Is MIT Auster approved. We are
·
clearing stocks to make way for our new Austel
approved range.
2 pair (4 core) was $0.75/metre or $48.00/roll (100m)
NOW $0.50/m or $29/roll (100m) cat. WB-1602
3 pair (6 coral was SO. 95/metre or $62.00/roll (100m)
NOW $0.65/m or $41/roll OOOm) cat. WB-1603
NEW FLAT 8 CORE AUSTEL APPROVED
NOW AVAILABLE Blackincolour
cat. WB-1625 $1.20 metre
~
The designs in this book are applicable for all types ,_.......,....
of high power sound reinforcement and musical
instrument amplification systems. The information given will
enable sound systems from fifty to several thousand watts to be
correctly made and installed.
The first part of the book is a comprehensive technical section
covering much of the theory of selecting and matching
loudspeaker components, electrical connections, crossover
design and use, with details of materials and methods of
construction. There are 30 designs shown in an easy to follow constructional drawings with
technical specification data. The recommended drivers are English.
Softcover-165 pages-292x207mm Cat. BC-1166
ONLY $24. 95
1 6 Tune Melody Doorbell
This doorbell plays 16 tunes - a different one each time
the pushbutton is pressed. It operates from 2 AA
batteries (not supplied) and includes pushbutton and
cable. And its all less than $15. Amazing!!!
Songs include - Twinkle Twinkle Little Star, Santa Lucia,
Oh! My Darling Clementine, Rockabye Baby, London
Bridge and more.
High Definition Audio'" is a new
technology that recreates the "Live"
performance sound. HOA is a
remarkable product designed to improve the quality of home Hi Fi sound. It will add a new dimension to your home audio
system. You will hear an increased "liveness" and "spacial" feel as well as improved bass without boominess and a
general improvement in sound quality. When we tested the unit we were rather sceptical, but after listening everyone was
yerv impressed! Its basically "Digital Sound Processing". You see this on very expensive surround sound decoders,
where you have a choice of different live hall sounds. Use it on your CD's, tapes, records, VCR, FM stereo, surround
sound processors etc.
Why are Jaycar selling HOA? HOA has generally been a bit of aflop. The unit was designed by a US Company who were
probably too greedy, as from what we can find out wanted nearly $200 for the unit. We purchased them at a fraction of
the cost, and have been able to sell them at about 25% of usual price.
How do you connect it? It can be connected: •Between the pre main and main power amps •To tape in/out sockets on
amp •lnline between an auxiliary device (CD, turntable, VCR etc) and amp •Connectors are RCA plugs - 2 in, 2 out •240V
to 12V AC plug pack supplied. Controls on the unit are on/off switch, bypass switch, LED and min-max HOA level control.
Unit is a black box with rubber feet which looks good on your stereo rack. Size 200(W)x132(D}x37(H) mm.
Bit Sceptical? We know you may be a bit sceptical (we were initially) tt you live near one of our stores call for a demo. If
you cant get to a store, we are offering a 14 day money back guarantee if you are unhappy with the unit. Simply return it
to us (in as new condition) within 14 days for arefund. (less post/pack charges you paid to get it). Limited qty available
Cat. AA-0500
Cat.XC-0275
*
$29.95
WELL BELOW NORMAL PRICE • ONLY $49.50
12V NICAD BATIERY CHARGER GIVEAWAY
I
I
I
These are in our
~~
I
catalogue at $17.50.
~ ~
We have found that
many of these have a problem
with them where the LED won't light, or one
of the charging bays doesn't work. So, we
are offering these at below cost. You can
now buy 2 for less than the price of one,
~---------~ and charge 6 batteries at a time! Note: As
the price is so low, they are being sold as is - NO RETURN I NO WARRANTY.
1-.::::::::
Cat. MB-3514
emokey is a keyring which will record messages
p to 20 seconds long. Ideal for remembering
telephone nos you see
whilst driving, or
reminding yourself to
phone somebody, do
something, a meeting,
flowers for the wife,
some thing you need to
do tomorrow the uses
are endless. Three
messages can be
'---""..,""'-------' recorded.•message
one: 8 secQnds • message two: 6 seconds • message
three: 6 seconds. If one message goes over its allocated
time, it simply records into the next message. Total
recording time is 20 seconds. Uses four 913 batteries
which will last for one thousand 8 second playback
times. A handy device utilising the latest in electronic
technology at an amazing price. Size 65 (L) x 38 (W) x
14 (D) mm and supplied with keychain.
only $7.50 ea
was $17.50
save $10 each
I
Low Cost Temperature Controlled Soldering Iron
Ideal hobbyist soldering
station. It operates on 240
1
volts, and the transformer
delivers a safe 16 volts to the
:
/
soldering iron.
It has a PTC (Positive Temperature
Coefficient) soldering tip at a constant temperature of
310°C which is ideal tor PC work. It has a 20 second
heatup time. Replacement Tip Cat TS1202 $9.95
Cat. TS-1200 WAS $49.95
NOW$39.95
6" WOOFER
Cat.
8" WOOFER
12" WOOFER
CW-2140~at. CW-214'*2at. CW-2145
SAVE $20
WAS $79.50
VE $25
WAS $115
VE $30
WAS $209
FEB $59.50
FEB $90.00
FEB $179.00
RE/SPONSE RE. SPONSE RE./SPONSE
THE LATEST KITS FROM JAYCAR
KC-5173 Talking headlight reminder (full kit) $59.95
$14.95
KC-5172 Minivox voice operated relay
$27.95
KC-5171 Auto nicad discharger
·
KC-5170 Twin diversity FM receiver
$199.00
KC-5169 LW AM weather receiver
$32.95
$47.95
KC-5168 High power dimmer
$29.95
KC-5167 Nicad zapper
KC-5166 Pre Champ preamp
$7.95
KC-5165 Steam whistle + diesel sound
$22.95
KC-5164 6V SLA battery charger
$29.95
KA-1765 Active subwoofer Xover - sl'fonn
$29.95
$69.95
KA-1764 Active subwoofer Xover - f/form
KA-1766 In a flash cable checker
$22.95
$129.00
KA-1 767 Mini stereo amplifier
$55.00
KA-1768 Sound record
KC-5174 3 spot sine oscillator
$59.95
KC-51 75 Dolby short form kit
$169.50
KC-5176 Enclosure kit
$69.50
KC-5177 DSB transceiver
$59.95
$12.95
KC-51 78 Clifford the cricket
KIT SPECIALS
$34.95
KA-1763 Temp controller was $44.95
KC-5145 LCD print indicator was $59.50
$49.50
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•Mon/Fri:9-5.30
ExperimentinJI
I
with Electronics -----~
by PETER PHILLIPS
Playing games with the 4060
For a change, this month we present a range of electronic game circuits that are fun to play with,
yet cheap and simple to build. They're based on a readily-available CMOS chip, the 4060.
The inspiration for this month's topic
comes from the US magazine Popular
Electronics, and three of our circuits are
similar in concept (although differing
considerably in detail) to those published in PE for September 1994, in the
section called 'Circuit Circus'.
We 're describing here four simple
and easy-to-build games circuits, including one you may not have seen
before, at least in an electronic version. The circuits can all be built on a
prototyping board, but you might
want to get more serious and build
them on strip-board and mount them
in a plastic box.
You might also think of ways of improving or expanding the games. For
example, in some games you can add
more sections to get another variable
(more of a challenge), or duplicate the
entire circuit for more players.
The read-out in each game is simply a
number of LEDs, and the way they're
arranged can make a game more intuitive and lifelike. This is another reason
to build the games into a box, as the
LEDs can then be arranged to suit.
You'll get the idea as we go along.
The main component in all our circuits is the 4060, a CMOS IC described
as a 14-stage ripple-carry binary
counter/divider and oscillator. To kick
off, here's a short introduction to this
inexpensive but versatile IC.
+V
fo•-1_
2.3xRtxCt
Flg.1: The 4060 Is a CMOS 14-stage
binary counter with its own Inbuilt
oscillator. The basic RC oscillator
circuit Is shown here. The equation for
the clock frequency applies only If R2 ls
much higher than Rt.
games circuits) which is a Johnson, or
ring counter.
This means the count sequence from
the 4060 is binary, rather than decimal
as with the 4017. However, for our circuits, a binary sequence is more useful.
Perhaps the main virtue of the 4060 is
its inbuilt clock oscillator. The basic oscillator connection is also shown in
Fig.I, where you can see that three ex+12
16
~
C1 10nF
9 Cle
Q4
The4060
The 4060 counter, shown in Fig.I,
has 14 internal counter stages, but only
10 of the 14 have accessible outputs. As
the pin-out diagram shows, the first
three stages (QO to Q2), and stage QIO
are not wired to external pins. The
lowest accessible division from the
counter is therefore 16, from output Q3,
and the highest is 16384, from Q13.
The count sequence is in binary, unlike the 4017 counter (used in PE's
90
ELECTRONICS Australia, February 1995
IC1
4080
•
LE01
C3l-'-'--I~-+ LED2
R3
1K
I
temal components are all that's needed
to complete the clock circuit The equation shown with the circuit is approximate and applies only if Rt is
much lower in value than R2. The purpose of R2 is to minimise the influence
on the frequency of the oscillator, of the
forward voltage across the input protection diodes.
Capacitor Ct is specified as a
capacitance anywhere from lOOpF up to
any practical value. However I've
found this to be somewhat hopeful, as
electrolytic capacitors tend to make the
oscillator unreliable, particularly with
high values for Rt and R2.
The minimum specified value of Rt is
lOk, and its, maximum is IM. I've
found the oscillator will function reliably with much higher values, certainly up
to 5.6M, with a lOM resistor for R2.
However, the equation for frequency is
no longer accurate with these values.
The counter has an active-high reset
terminal (pin 12), so this pin is
grounded for all our circuits. Like most
CMOS digital ICs, the 4060 can operate
from a supply voltage ranging from
around 3.5V to 15V. Our circuits are
designed for a 12V DC supply, but can
easily be adapted to different voltages
by changing the value of the LED current-limiting resistor(s).
For instance, to make the games portable, run them from a 9V battery and
use a 680 ohm resistor for the currentlim i ting resistors, rather than the
specified lk.
Two-up
This very Australian game is our first
entry, mainly because it's also the
simplest. The circuit is in Fig.2. The
Flg.2: This slmpledeclslon maker circuit clock frequency is around 3.5kHz, set
Is also the electronic equivalent to by Rl and Cl.
When the button is pressed, the clock
Two-up. Press the button and one of
four possible displays w/11 result, just as oscillator circuit is completed and the
counter is cycled through its sequence,
with two coins.
so fast that the LEDs appear to be on all
the time.
When the button is released, the oscillator stops, leaving the counter set to
a random number. The two LEDs are
therefore either both on, both off or left
with either one on. Like throwing two
pennies in the air!
To change the operating frequency,
change the value of Rl. A lOOk resistor
makes the oscillator slow enough to see
the LEDs pulsing when the clock is
running. For 9V operation, make R3 a
680 ohm resistor.
The LEDs are grouped into threes,
with separate current limiting resistors
per group of three. This is needed because if all six LEDs share the same
current limiting resistor, their brightness
falls off noticeably when more than
three LEDs are on.
As before, pressing the button lets the
counters race continually through their
cycle. When the button is released, you
are left with a random display from
both counters.
To get the best effect, arrange the
LEDs for each counter like the dots on
a dice, as shown in Fig.3. This way, a
number is simply the number of LEDs
left on. Obviously each number (except 0 and 6) will occur with different
LED patterns, which means getting a
six (or zero) is more difficult than any
other number.
A variation is to make both counters
independent, with individual clock circuits and pushbuttons. This way you
can 'roll' one dice until a six is obtained, then 'roll' the other until it
comes up as a six.
An interesting thing you can try with
Figs.2 and 3 is to use a touch pad,
rather than the pushbuttons and the RC
oscillator circuits. Being CMOS, the
clock input of the 4060 has a very high
Dice
Called 'Craps' in the US, this is a
dice rolling game, in which the winner is the first to get two sixes. In our
simulation, shown in Fig.3, two
counter circuits are needed, one for
each die. The clock frequency is
around 15kHz, faster than the previous circuit, mainly because the circuit uses higher-order outputs. A
slower frequency makes these outputs
change at a visible rate.
The oscillator circuit of ICl also
provides the clock signal for IC2.
Notice that the clock connection for IC2
comes from pin 9 of ICl, as this pin has
the lowest impedance output.
impedance, and you'll find the counter
will cycle if you touch pin 11.
Poker machine
When poker machines were mechanical, you pulled a handle to make three
or four drums rotate. These days you
simply press a button and watch a computer screen.
Our poker machine simulation features a mechanical 'feel', in which each
'drum' (or counter display) runs at full
speed until you release the button, after
which the displays change at an everslower rate until they become stationary. You win if the three displays are all
the same.
The circuit, shown in Fig.4, has three
4060s, each with outputs Q3-5 connected to three LEDs. If you want to
make the odds more difficult, add
another LED to output Q6 (pin 6). Arrange the LEDs as shown.
The oscillator of ICl drives the other
two counter ICs. Add another stage like
IC2 or IC3 for a 'four-wheeler'
machine. The oscillator circuit is identical to the previous circuits, except that
a light dependent resistor (LOR) is now
the timing resistor.
To get the effect of numbers changing
more slowly and eventually grinding to
+12
+12
+12
,.
R31M
1t Q.K
C2
470µF
R2
IK
~---
J
Q5 •
LORI /tit
"""'
-- -Cl
Q3 7
-
LEDi
•
LED3
R4
1K
':"
+12
+12
16
~
LO
J
Q5 •
11 CU<
ED
ng
IC2
Q4
"""'
s
4060
Q3 7
RS
IK
•
+12
11
J
Q5 •
11 CU<
IC3
°'
6
4080
Q3 7
-RST
i
•
-
LED4
"""'
LED7
R6
1K
•
Flg.3 (above): Roll the dice! If the LEDs are arranged In
groups of six, you'll find this game much easier to play.
Fig.4 (left): This electronic poker machine circuit has a
mechanical 'feel'. When the button Is pressed and released,
the displays change ever more slowly before reaching their
final value. The construction of the LED-LDR optocoupler is
shown here as well.
ELECTRONICS Australia, February 1995
91
EXPERIMENTING WITH ELECTRONICS
feel as an old mechanical 'pokie', in
which the speed at which the handle is
pulled controls how fast the drums
pletely. The displays will also freeze rotate. In our circuit, this effect is
created by R 1.
when the oscillator stops.
If the button is pressed
for
To keep the effect as life-like as possible, the circuit needs to also respond a short time, capacitor C2 won't be
to how quickly the button is pressed. able to charge fully, giving a slowerThat is, we need to recreate the same changing display than if the button is
held for a longer time.
Simple, but effective!
The LDR-LED 'opto
coupler' is very easy to build.
+12
Insert a Smm diameter LDR
16
into one end of a piece of
11 CLK ~
---IR\/2'<fl1M'~-.!.!..1
black Smm plastic tubing
and a Smm LED into the
R3
11<
other. The LED should just
touch the surface of the LDR.
Then seal both ends of the
tubing with plasticine or 'blu+12
tac k' to get an absolutely
light-tight assembly. Measure
the resistance of the LDR to
confirm that the package is
properly sealed. Ideally, the
LDR resistance should read
infinity, or at least five or
more megohms.
+12
You should find the oscillator actually stops running
when the capacitor has discharged, leaving the display
of each counter frozen. But
like the real thing, one 'drum'
will often finally click into
place just when you thought
R10
the display had settled ...
11<
a halt means that the counter clock frequency must run at full speed while the
button is pressed, then gradually slow
down and stop after the button is
released. This is not as easy to do as it
might sound, especially if you want to
keep the circuit simple.
To achieve this here, I've
resorted to a basic technique
in which an LDR is encased
with a LED. Providing the
enclosure is light-tight, the
resistance of the LDR will
depend entirely on the light
output of the LED.
In our circuit, when PB l is
pressed, current flows through
R 1, R2 and the LED. The
LED glows at its maximum
brilliance, and the LDR resistance drops to a few thousand
ohms. As well, capacitor C2
charges via R l.
When the button is released,
the capacitor discharges
through the LED, via R2,
keeping the LED lit for a
time. As the capacitor discharges, the light output of the
LED falls. This causes the
resistance of the LDR to increase, which reduces the frequency of the oscillator,
making the displays change
more slowly.
After a few seconds, the
capacitor discharges completely and the LED is completely extinguished. If the
assembly is light-tight, the Flg.5: Care for a game of Snap? Deal the cards by pressing
resistance of the LDR will PB1 or PB3. Pressing PB2 turns on LED9 and freezes the
now be many megohms and displays from IC1 and IC2. If the two displays are the same,
whoever pressed PB2 wins.
the oscillator will stop comr-
Snap
In the card game of Snap,
the winner is the player who
first shouts 'snap' when two
cards of the same type appear.
Continued on page 101
PARTS LIST
Two-up
Dice
Poker Machine
Resistors
Resistors
Resistors
Resistors
All 1/4W, 5%:
10k
R1
1M
R2
1k
R3
All 1/4W, 5%:
R1
10k
1M
R2
R3-6
1k
All 1/4W, 5%:
R1
330 ohm
R2,4-6
1k
R3
1M
LDR1
Smm button type
All 1/4W, 5%:
R1,8
100k
R2,7
1M
R3-5,9,10 1k
47k
R6
Capacitors
Capacitors
Capacitors
C1
10nF polyester
Capacitors
C1
1nF polyester
Semiconductors
Semiconductors
IC1
4060CMOS
binary counter
LED1,2
5mm reel LED
IC1,2
LED1-12
Miscellaneous
Miscellaneous
Normally-open pushbutton,
single pole; +12V DC power
supply.
Normally-open pushbutton,
single pole; +12V DC power
supply;
92
ELECTRONICS Australia, February 1995
4060CMOS
binary counter
5mm reel LED
C1
C2
Snap
0.1 uF polyester
C1,3
470uF 25V electrolytic C4
10nF polyester
22uF 25V electrolytic
Semiconductors
Semiconductors
IC1-3
01-3
IC1,2
LED1-10
4060CMOS
binary counter
5mm red LED
Miscellaneous
Normally-open pushbutton,
single pole; 25mm length of
5mm black plastic tubing, plasticine or similar to seal ends;
+ 12V DC power supply.
LED1-9
1N914 signal diode
4060CMOS
binary counter
5mm reel LED
Miscellaneous
three x normally-open pushbuttons, single pole; 25mm supply.
NEW BOOKS
Circuit, device theory
ELECTRONICS THEORY AND
PRACTICE, by Gerado Mesias. Butterworth-Heinemann, 1993. Soft
cover, 190 x 245mm, 260 pages. ISBN
0-75061679-2. RRP $45.95.
While it's not likely to win awards for
presentation, and despite its predictable
content, this book has a number of features that make it worthwhile considering as a text for a university or TAFE
level electronics engineering course.
Perhaps its main feature is the number
of worked examples, which are all set on
a grey background. In fact, there are so
many worked examples that you can flip
through up to 10 pages at a time and
never see a white background. The publisher claims there are over 350 worked
examples and more than 700 diagrams.
The first chapter revises the basics Ohm's law, Kirchhoff's laws, Thevenin
and Norton's theorems, superposition
theory, mesh analysis and so on. Then
come chapters covering transistor theory,
starting with biasing, moving through
transistor models, load lines and ending
with cascaded systems.
Next covered is Bode plots, followed
by a chapter on capacitance and high frequency transistor circuits. The last three
chapters deal with operational amplifiers, quite extensively.
The book is aimed at the first year engineering student, and the writing style is
surprisingly friendly for a book of this
type. The author is a senior lecturer in the
Department of Electronic and Electrical
Engineering at DeMontfort University,
and he is obviously at home with the
subject matter, and aware of the need to
give students lots of worked examples.
The review copy came from Butterworth-Heinemann, PO Box 345, North
Ryde 2113. (P.P.)
Circuit simulation
INSIDE SPICE: OVERCOMING
THE OBSTACLES OF CIRCUIT
SIMULATION, by Ron Kielkowski.
Published by McGraw-Hill Books,
1994. Hard covers, 235 x 155mm, 188
pages with 3.5" floppy disk. ISBN 007-911525-X. RRP$135.
As anyone who has tried using a
SPICE package can attest, simulating a
circuit is rarely as straightforward as you
expect. Even after you get used to
SPICE's little idiosyncracies like insisting on 'MEG' for the H>6 unit multiplier,
and sometimes refusing to run a simulation unless you add 100-megohm resistors to remove 'floating nodes' in your
circuit, there are still the dreaded nonconvergence failures, numeric integration failures and timestep control errors.
All of which can make your simulation
take twice as long as simply building up
and testing your circuit on the bench and still give you dubious results.
This new book by US simulation expert Ron Kielkowski is intended to help
anyone using a SPICE simulator understand exactly how they work, why
they're unfriendly at times, and how to
overcome their limitations.
After explaining how SPICE was developed, he then gives an (excellent) introduction to the way it actually works.
Then follow chapters on non-convergence, numeric integration, timestep
control, and SPICE simulation options
and their manipulation. It's all written in
clear, highly readable language, and
AH!- THE.
WONDER
.
OF IT
ALL!
!
• ·
•
'*1
·,~
_
AJOUR.'IEYBACKl"i
TIWE. TO THE !.«GICAL
REALi\.fS OF EAR.'.Y WIAfiESS.
CRYSTAL SETS 'N' SUCH
By R.J. YOUNG
~;/P.li'll-.<:$$~~.f%;?JW:~"\.°""imJ~
seems to me exactly what many of us
have been waiting for.
The accompanying floppy disk gives
free copies of a 32-bit PC simulator
called RSPICE and a graphical postprocessor called RGRAPH (both developed by a team led by Mr Kielkowski at
RCG Research), plus circuit files for
many of the examples discussed in the
text. As RSPICE is SPICE2G.6 compatible, the files are also suitable for popular
packages like IsSPICE and PSPICE.
In short, my impression is that this
book is a 'must have' reference for anyone working with a SPICE simulator.
The review copy came from McGrawHill Australia, of 4 Barcoo Street,
Roseville 2069. (J.R.)
Old-time radio
CRYSTAL SETS 'N SUCH, by R.J.
Young. Published by the author, 1994.
Soft covers, 221 x 140mm, 142 pages.
RRP$19.95 including P&P.
Bob Young is a vintage radio enthusiast living in Benalla, Victoria. A member
and past President of the Vintage Radio
Club of North-East Victoria, he has a
special interest in crystal sets and has
built many of them - including one that
won the Club's Hellier Award, last year.
I gather that he's written this book as a
'labour of love', to help the modern
reader not only understand the operation
of crystal sets, but also to get a good
understanding of the part they have
played in the evolution of radio communications. Its cover subtitle reads 'Ajourney back in time - to the magical realms
of early wireless', and that helps convey
the effort he makes to explain the enormous appeal crystal sets had in the early
days of radio, to so many people.
The text combines a nostalgic look at
the origins and early development of radio, with some easy introductory material on AM radio, how crystal sets work
and how to build them. This is all presented with a friendly leavening of humour, plus a variety of appropriate
illustrations - including period pictures,
adverts and diagrams.
It all makes entertaining and informative reading, and would make a great gift
for anyone interested in early radio. Copies are available direct from Bob Young,
RMB 1561, Benalla 3673. (J.R.) •:•
ELECTRONICS Australia, February 1995
93
Information centre
Conducted by Peter Phillips
Fuses, baluns and electrically charged rain
In the first part of this month's column I honour a promise I gave earlier, by discussing glass fuses.
We then continue with reader inspired topics ranging from variable speed CO players to milligauss
meters.
Some time ago we had a number of
questions about fuses raised in these
columns, and I promised I would research and further discuss the matter. As
a result, several readers sent me
material, which has been waiting on file
until I had room in the column to use it.
This month I'm making room, as I like
to keep to my promises, even if it takes
a while.
While there are dozens of different
types of fuses, we only have space
for those typically found in
electronics, in particular the glass
fuse. And I doubt if what I've
found answers all the questions.
You might remember that the most
contentious issue was the voltage rating
of a glass fuse. Certainly there's lots
said in the literature about voltage
rating, but I have drawers full of glass
fuses that don't have a voltage rating
stamped on them, and I've seen many
more in the various electronic shops. So
what about these fuses? Can I assume
they are rated for 240V operation. If
not, what is their voltage rating?
From my research, it seems most
glass fuses sold in Australia are rated at
250V, unless otherwise marked. I conclude this on the basis that it appears
that these fuses are made with three
voltage ratings: 250V, 125V and 32V.
Given that we don't use many 125V
rated fuses in Australia, and that 32V
rated fuses are generally marked as
such, it seems that in the absence of a
rating, you may assume 250V. Not a
good situation, but when you read the
section on voltage rating, I think you'll
come to the same conclusion.
But certainly this short look at fuses
is rather overdue, and my apologies to
those readers who sent me material and
have been waiting ever since to see it
94
ELECTRONICS Australia, February 1995
appear in the magazine. Naturally I'm
interested in any comments you might
have. Perhaps I didn't cover everything,
or have got something wrong ...
Fuses
Edison first patented fusing in 1880,
and since then fuses have become an
essential part of our technology, with
different types made for the many different types of circuits they protect.
Our main interest here is the glass
'cartridge' fuse, commonly called type
M205 for the 20 x 5mm size, and 3AG
for the 6.3 x 32rnrn (1.25" x 0.25") size.
Both of these fuses have the same construction: fuse wire soldered to metal
endcaps that are fitted to both ends of a
length of glass tubing, which encloses
the fuse wire.
Standards: There are several standards for glass (or miniature) fuses, and
those we are likely to see in Australia
are the UL standard (Underwriters
Laboratories), the IEC (Electromechanical Commission) and the CEE
(International Commission on Rules for
the Approval of Electrical Equipment).
The UL standard is from the US, and
the IEC and the CEE standards cover
Europe and Asia. The problem is the
standards vary quite a bit, so a fuse
made to one standard may not suit
equipment that uses a fuse made to
another standard. To see the differences,
we need to examine each fuse characteristic in tum.
Current rating: The most essential
thing to know about a fuse is its current
rating, which is the current the fuse can
carry continuously at a normal operating temperature (between 20° and
25°C). This rating changes when the
operating temperature of the fuse changes, as shown in the graphs in Fig.1.
However, depending on the standard
the fuse is made to, there can be a big
difference between the current rating of
the fuse and the current that causes it to
blow. For fuses made to the UL standard, the current rating stamped on the
fuse should exceed the normal operating current of the circuit it is protecting
by at least 25%.
For fuses made to the IEC standard,
the current rating is about the same as
the operating current of the circuit the
fuse is protecting. Put another way, a
circuit taking 1A can be protected by a
lA fuse made to IEC standards, or with
a 1.4A fuse made to the UL standard.
Operating speed: If the electrical
equipment protected by a fuse takes a
considerable current surge at switchon, the fuse needs a built-in time
delay so it won't blow each time the
equipment is turned on. On the other
hand, equipment that uses thyristors
needs very fast acting fuses, so the fuse
will blow before the semiconductors.
Accordingly, fuses are made with different operating speeds.
The fastest is the super quick-acting
fuse, type FF, which is suitable for
protecting thyristor circuits. The standard fuse (Normal Blo) is called a quickacting fuse, type F. These suit a
situation where there's little or no current surge either at switch-on, or under
normal operation. Some types of F
fuses are filled with an arc-quenching
filler, which gives an improved breaking capacity. These types are sometimes
suitable for protecting semiconductors.
The medium time lag fuse (type M)
can handle small surges, but the more
usual time lag fuse is the type T fuse,
also called the 'Slo Blo' fuse. The
slowest of all is the super time lag fuse,
type TI.
Voltage rating: ·The rated voltage of
a fuse is the maximum voltage at which
the fuse can safely interrupt a short-circuit. The usual voltage ratings are I 25V
and 250V, although automotive fuses
are generally rated at 32V.
Incidentally, a fuse can be safely used
in a circuit that has a lower operating
voltage. That is, you can use a 250V
rated fuse in a I 2V automotive system,
but you should not use a fuse in a circuit where the working voltage is more
than the voltage rating of the fuse.
Current breaking capacity: This is
the maximum current the fuse can safely interrupt at its rated voltage. Fuses
rated at I 25 volts that carry the UL
mark are tested with a fault current of
I O,OOOA. UL specified 250V rated fuses
can be tested differently, where IA
rated fuses must safely interrupt 35A.
The test current for fuses between I A
and 3.SA is IOOA; between 3.5A
and lOA it's 200A, from lOA to
15A it's 750A, and those between ISA and 30A are tested
with a ISOOA current. The
10,000A test is also allowed for
250V rated fuses.
The IEC standards require
that M205 fuses are tested at
250V. The 3AG sizes are tested
at different voltages, depending
on the current rating. For a current rating up to 2A, the test
voltage is 250V, for current
ratings from 2.5A to 4A it's
150V, and 60V is used for current ratings from 5A to lOA.
High-breaking capacity fuses
are tested at 1500A AC, and
low-breaking capacity fuses at 35A, or
10 times their current rating, whichever
is the greater.
Voltage drQp: We don't usually think
about the voltage drop across a fuse, but
being a thermal device, a fuse not only
has resistance that causes a voltage
drop, it dissipates heat as a result. The
voltage drop across a typical IA M205
fuse is a few hundred millivolts, and
power dissipation can be 0.5W or more.
The resistance of a fuse is usually a
very small part of the total circuit resistance. However the resistance of fuses
with a current rating less than IA can
be enough to cause problems in low
voltage applications, where the voltage
drop across the fuse is significant.
The fuse element in a glass fuse
usually has a positive temperature coefficient, which means the resistance of
the fuse increases with temperature. The
cold resistance of a fuse is measured at
a current of no more than 10% of the
fuse's current rating. The hot resistance
is measured at a current equal to the
current rating of the fuse.
Pt rating: Also called amperessquared-seconds, this rating determines
how much energy a fuse can pass.
When multiplied by the resistance of
the fuse, the energy dissipated by the
fuse itself over time t can be found. A
fuse. with a small I2t value passes less
energy and therefore imposes less stress
on the circuit being protected.
Other characteristics: There are
quite a few more characteristics that
describe a fuse. One of these is the cutoff characteristic, which is a rating of
how fast the fuse isolates the fault current. This relates to how quickly the arc
developed across the melting element is
extinguished. If for example a fuse arcs
for a half cycle of the 50Hz mains,
energy will be passed to the circuit
being protected for 1Oms - which
rated voltage, rated current in milliamperes or amperes, maker's name or
trademark, and a symbol denoting the
time/current (or delay) characteristic.
Acknowledgements: This information has come from various sources, including a publication from Radio
Spares (Miniature Fuses, B9883) and
from an article by Ray Porter (M.Sc.,
C.Eng., MIEE) in the January 1994 edition of the UK magazine Television.
Variable speed CD
We now resume our usual role, starting with a letter from a ballroom dancing teacher:
I am a ballroom dancing teacher, and
also a dabbler in electronics. Dance
studios are changing over to CD
players for their music needs, and I'm
often asked how to fit a speed control to
a CD player, as I do to cassette players.
None of the technicians I
know have any idea how to do
this, but it is currently available
on a Denon player, and I have
seen it fitted to several Technics
players as a modification.
The required variation is
from about 10% to 20%. Perhaps you could investigate this
as an article or project in your
magazine. (Alan Boulton,
Rothwell, Qld.)
Years ago when a friend and
I brought Percy Grainger's
pianistic skills back to life
20 40
-40 -20
60 80 100 120
0
through a reproducing piano
operating temperature in degrees C
roll, we amazed the recording
Flg.1
technicians by being able to
slow the roll without affecting
could be enough to destroy it, or at least the pitch. In fact the speed of the music
cause damage.
could be slowed almost to a standstill,
Although not a characteristic as such, with no change in pitch.
time delay fuses have a finite lifetime,
Because a piano roll is essentially a
as the number of surges the fuse can digital recording, I imagine the same to
survive is limited. The rate of deteriora- be possible with a CD player. However,
tion depends on the I2t value of the cur- I can't immediately think how best to
rent pulses, which can explain why do this. Perhaps this has been done by a
some fuses fail when there's no prob- reader, in which case I'd be keen to
lem in the circuit they are protecting.
describe the details. This is about all we
Conclusion: The standards relating to can do at this stage Alan, as the large
miniature fuses are: UL 198G, IEC range of CD players makes it rather difPublication 127, CEE Publication 4 and ficult to present this idea as a project.
a fourth from Canada, CSA C22.2. The
CSA (Canadian Standards Association) More on baluns
standards are similar to the UL 198G
In the December '94 edition, I disstandards regarding interrupting and cussed baluns when a reader wanted to
blowing requirements, but have dif- know how they can possibly work. The
ferent specifications concerning permis- next letter makes a few more comsible temperature rise of the fuse body.
ments, including something I didn't
A fuse made to the UL standards must know about rain.
be marked with the name or trademark
It has always puzzled me why a conof the manufacturer and its electrical ventional balun circuit (see Fig.2) is
current and voltage ratings. IEC or CEE better than a toroidal 4: 1 matching
specified fuses must be marked with the transformer. The grounded centre tap
ELECTRONICS Australia, February 1995
95
INFORMATION CENTRE
on the 300 ohm side is to prevent a
build-up of static charge on the dipole,
but if grounding it directly prevents a
problem, then grounding it via a lOOk
resistor should also work.
While on the subject of static buildup, I have been able to keep a 20W
fluorescent tube lit continuously by connecting it between my long wire antenna for HF and ground during a rain
shower (not a thunder storm). It seems
every drop of rain carries a static
charge which is imparted to the antenna
on contact.
Incidentally, your explanation about
baluns is a little confusing when you
talk about 114-wave sections. For channel 0, a 114 wavelength is l .66m, while
for channel 11 its 0.34m. (David Dorling, Buderim, Qld.)
If you think I'm an expert on baluns,
David, please let me disabuse you. One
of my many weaknesses in the vast
field of electronics is anything to do
with high frequencies. The information
I presented in December (as I said at
the time) was researched from various
texts on the subject. They all refer to
the 1/4-wave section, but just how a
coil of wire simulates a 1/4-wave section is something I accept, and don't
question. I learnt why once upon a time,
but have long since forgotten.
By the same admission, I suspect you
are right in saying that a balun can be
connected to ground through a high
value resistor. But why you would want
to do this? Perhaps as some form of
protection against lightning?
I'm most intrigued by your comments
about rain carrying an electric charge.
In fact, from your experiment, it seems
the voltage passed to your antenna and
thence to the tube is quite high. Free
electricity, if we could only tap into it
(pardon the pun).
bifilar windings
300ohm
75ohm
balanced
unbalanced
Flg.2
and such a project is now viable. It
shouldn't be long!
Regarding a full Dolby ProLogic system, things are not quite so easy. The
main problem is the licensing cost.
Typically, the licensing cost to use
Dolby ProLogic !Cs is $10,000 or
more, which is better than the $100,000
fee quoted when we made enquiries in
1992, but still significant.
The only way we could do such a
project is in conjunction with a kit supplier who would pay the fee and recoup
it from selling kits. Whether this is a viable thing to do is uncertain, as the cost
of a kit would necessarily be quite high.
And all this has to be considered in a
market where prices of commercial
Dolby ProLogic equipment are falling.
Milligauss meters
In November '94, a reader asked
where he could buy an instrument to
measure electromagnetic radiation. I've
since received information that will
help our reader (S.K., Penrith), and
others who might want to do the same.
Surround sound delay unit
One of our most popular projects has
been the Surround Sound Decoder
project published in January 1992. But
one of the most commonly asked questions about this project is this:
I am writing to ask if EA has since
published details of a delay section for
this project. Also has any consideration
been given to publishing a project for a
full Dolby Prologic system? (David
MacCullum, New Plymouth, NZ.)
I'm pleased to be able to report that
the design for a delay unit for the Surround Sound Decoder is on its way. The
cost of the ICs has since come down
96
ELECTRONICS Australia, February 1995
Incidentally, electromagnetic radiation is made up of two fields: the magnetic and the electric field. When
associated with a 50Hz power source,
these fields are in the extra low frequency range (ELF). Frequencies
from around 2kHz to 200kHz are classified as being in the very low frequency band (VLF).
The first bit of information was a
copy of an article from the March/April
1994 publication IEEE Transactions on
Industry Applications, Vol. 30, No. 2.
The title of the article is 'Electric and
Magnetic Fields: Equipment and
Methodology used for Obtaining Measurements', by Donald W. Zipse.
The article is written for the professional engineer, and is therefore quite
technical. However, it makes many
good points that will interest the layman
and gives a list of suppliers of suitable
measuring equipment. Unfortunately
the list covers suppliers from everywhere except Australia.
However I've discovered a local supplier of milligauss meters: Consultee
Electronics, 83 Flinders Street, Mentone, 3194; postal address PO Box
1161, South Melbourne, 3205. Phone
(03) 585 1159; fax (03) 584 1169.
This supplier has a range of portable
ELF and VLF milligauss meters, made
by Teslatronics. The advertising literature for the instruments says: Whether
you are a professional who needs a dependable hand-held magnetic fielo
meter, or simply a concerned individa1
who wants to reduce home 01
workplace exposure to low frequencJ
magnetic fields, Teslatronics has G
gauss meter to fit every application
without spending a fortune.
I've yet to hear of a local supplier ol
an instrument that measures the strength
of an electric field, although as I understand it, an ELF magnetic field is the
main concern.
Equation chart
OHMS LAW EQUATIONS
0
Ill
II
Current in Amps
Resistance in Ohms
Potential in Volts
m
Power in Watts
flg.3
Here's a contribution that I'm sure
many readers will welcome ...
My father, a long-time subscriber to
Electronics Australia, devised this chart
(see Fig.3) some years ago to help fellow radio hobbyists and others. I have
produced it as a computer graphic, and
suggest it might be of interest to your
readers. It could make a useful cut-out
or backing to a bookmark. (Ian Stein,
South Perth, WA.)
Many thanks Ian, for sending us this
chart, which is reproduced in Fig.3. A
oscillation
stops
here
I
An Electronics Australia
Publication
A Basic Guide to Colour
,.,,
diode stops these
oscillations
V, = JI -cos( b 1) ] :~:;::n:~~:
'l
"LC
closed
(2) V, =~I -cos( n:g)] =2E
(I)
Flg.5
All relillOrS me one ohm
Flg.4
most useful item, as Ohm's law and related power equations are used regularly by most of us at one time or another.
October's What??
Because of the lead time in preparing
the magazine, the first reader-supplied
solution to the October What?? question
dido 't appear until December. As a
result, I've been overwhelmed with
solutions to the question, as many
readers thought no one else had
responded. Two of these contributions
have now been presented, and I
promised to include more.
However, on looking through the
many letters, I find that most of the
solutions are similar, and there seems
little point in repeating ourselves. So
we'll call it quits on the subject, and
many thanks to those who sent me a
solution to the problem.
What??
This month's question comes from
David Minns (Gracemere, Qld) who
was one of the many to send a solution
for the October problem. David's question concerns yet another arrangement
of resistors and, unlike the October
question, includes a solution (thank
goodness!). Here's the question:
What is the resistance between any
two adjacent nodes in the infinitely
large mesh of one ohm resistors shown
in Fig.4? For example, between nodes A
andB.
Answer to
January's What??
The voltage across the capacitor will
be exactly 2E volts. That is, twice the
source voltage! The diode is initially
forward biased and is replaced with a
short-circuit. Using Kirchhoff's voltage
law, a differential equation that
describes the circuit can be written. The
solution of this equation is in Fig.5.
The LC resonant circuit thus begins
to oscillate, with the current I increasing
to the sinewave peak, but then decreasing to reach zero at time (t) = pi times
the square root of LC. The current then
'attempts' to become negative to continue oscillation, but at this point the
diode becomes reverse biased, and the
current stays at zero. That is, the circuit
stabilises.
Thus the capacitor remains charged at
the voltage across it at time t. Substituting for time t in equation ( 1) gives
equation (2), which solves to 2E. The
theoretical current waveform is also
shown.+
NOTES AND ERRATA
PC Interface for DSE's Teletext Decoder (June 1993): The diagram shown on
page 66 (Fig. I) is a little misleading, as it shows the two pullup resistors (R64 and
R65) still connected to R66 and R67 after the modification has been completed.
Since the new components are connected in series with R66 and R67 (by liftirig one
end of each resistor), the pullup resistors should be shown at the IC8 end of the
communications bus - R64 at pin 13, and R65 at pin 12.
Versatile 40V/3A Lab Power Supply (December 1993 and January 1994): There
is an error in the component overlay diagram shown on page 70 of the January
issue. The three connections from the power transformer should be reversed in
order, so that the 'CT" connection is on the left rather than the right, and therefore
connects to the OV line as shown in the schematic. Thanks to Robert Payne of
South Australia for bringing this to our attention.
TV & VCRs
Two very popular series of articles, published in Eectronics
Australia in the late 1980's, have
now been combined into a
separate publication.
Students, the home handyman, even the serviceman, will
find that the latest publication
from Electronics Australia gives
a wide and comprehensive insight into the electronics involved in colour television and
video cassette recording.
The author, David Botto, is a
television, video and electronics
service engineer with many
years of 'on-the-bench' experience. He's also designed,
constructed and maintained a
wide range of test instruments.
David's wealth of experience
and vast knowledge of colour
television and VCR's have now
been put together to give you
the facts, figures and basic
knowledge you need, to understand just how these entertainment machines work.
Available now from your local
newsagent or by mail order.
Price in Australia is $4.95, with
an extra charge of $2 for post
and packaging, when ordered
by mail, from -
The Book Shop,
Federal Publishing Company,
P.O. Box 199,
Alexandria, NSW. 2015
ELECTRONICS Australia, February 1995
97
Vii 1r11ta1 g1 e
ll2 01 di ii
1
1()
by PETER LANKSHEAR
Good advice: 'Caveat Emptor'
The Latin phrase in this month's column, which is written especially for newcomers to radio
collecting, is the time-honoured reminder that it is a purchaser's responsibility to be on guard. I was
prompted to write on this topic when recently I encountered an instance where an enthusiastic, but
inexperienced, collector got a little out of his depth ...
An acquaintance of mine, who is a chassis should still be as original as pos- and the substitute aerial coil has a
relative novice to the hobby of vintage sible. In this case, as it was hoped that shortwave winding implying
radio, has been impatient to obtain a eventually the receiver would be fully bandswitching, which is an anachronism
'cathedral' model radio and was restored and operating, it was time for a in a 1931 A.K. receiver, and of course is
delighted recently to have tracked down critical look.
the reason for the extra control knob.
a classic example - a 1931 Atwater
Of the original valve sockets, only
Modern IFT's
Kent model 80, rare enough in New
those of the rectifier and power output
Zealand and even rarer in Australia. It
Comparison of the photograph of the stages remain. Notably absent is an Atwas not in working condition, but had chassis with that of a model 80 in original water Kent oddity, a type '27 oscillator
been kept as an ornament. After much condition gives an idea of just how much valve mounted inside the oscillator coil
persistence, the reluctant owner, who in- modification there has been. Where there and its open topped shield. Missing from
cidently, is not a collector, was persuaded should be a single large circular IF transthe rear of the chassis are the name plate
to part with radio in exchange for a size- former, there are two much more modem and the aerial trimmer capacitor with its
square IF cans, clearly labelled 'Sickles', knob. In fact, apart from two valve
able sum of money.
I was invited by the excited
sockets and two remaining
new owner to approve the purshield cans, practically the only
original components remaining
chase, but even at first glance,
it was apparent that it was far
are the tuning capacitor and the
from being in original condipower transformer which, inciden tl y, has tell-tale black
tion. Immediately obvious was
an extra control knob in the
deposits around its cover - a
centre of the front panel and
sure sign that a rewind will be
required. That one item alone,
from even a cursory look at the
with freight, would not leave
chassis it was apparent that
much change from $100.
there were non-standard parts
With the chassis upended,
fitted.
Although it is unreasonable
there is more evidence of vandalism. Amongst the collection
to expect absolutely mint
of minor 'foreign' components
condition, to justify being in the
there is, as anticipated, a
upper price bracket a receiver
should be in good physical
relatively modem wavechange
shape, and major components
switch. At some stage there
should be authentic. This is
has been a wholesale gutting
and 'modernisation', and to put
especially so in the case of
it bluntly, in its present state, the
equipment from manufacturers
chassis is of very little worth.
such as Atwater Kent, who
used their own unique parts.
Alternatives
At this stage the question had
The new owner is philosophito be asked as to what was excal and optimistic.· A lot of
pected of the radio. If it was for
money has already been spent
static display only, then it
for a receiver that is not playable
needed only to have the cabinet
(or even displayable). The
refurbished, leaving the chassis
'as is'. This is always an option,
This classic Atwater Kent model BO In original condition cabinet has been given to a furespecially with very early Is from the writer's own collection. Its attraction to an niture restorer to refurbish and
equipment, but for a classic enthusiast Is understandable but Is the expense and attempt to conceal the extra shaft
hole. Restoration of the chassis,
radio to have any real value, the effort as featured this month, justified?
98
ELECTRONICS Australia, February 1995
Atwater Kent's nickel
plated chassis have
a very distinctive
appearance and
novel features. In
several models,
including the 80
shown here, to save
space, the oscillator
valve fits inside the
oscillator coil. The
valve can be seen
here, projecting
through the open
topped shield to the
left of the tuning
capacitor.
while not absolutely impossible, would
require a considerable degree of luck in
finding parts, skill, facilities and time
- and there remains the fact that extra
holes have been drilled, some in conspicuous places.
Obtaining genuine replacement components of rare receivers can be a problem, because radios of this class are not
often written off simply to provide
spares. Even if authentic parts can be
found, the owner feels that he will need
a lot of assistance, as he hasn't sufficient experience to tackle the major restoration work required and even the
most skilled restoration will not make it
a mint specimen.
Realistically .the chassis may be
beyond salvaging, and a better approach
would be to look for a substitute. Chassis
sometimes become available when their
cabinets are in such a poor state as to be
beyond repair, or become insect-ridden
and have to be destroyed.
My recommendation therefore to our
enthusiast, is in the first instance to advertise for a chassis in better condition. If
this is unsuccessful, as it could well be
bearing in mind the rarity of the model,
he might be better to cut his losses by
selling the restored cabinet, although he
would be left with only an expensive experience, rather than the cathedral radio
he so much desires.
Important lessons
What lessons are there in this, and what
precautions can inexperienced enthusiasts
take to avoid similar experiences?
The best policy would be to seek the
assistance of a seasoned and knowledgable collector, and I would point out
that it is a major function of vintage radio
societies to provide this kind of help and
advice. However, for inexperienced collectors on their own, here are some hints.
First, is the receiver what it is claimed
to be? Confirming the date of manufacture of a receiver requires a lot of ex-
perience. Taking the word of the owner
can be a very unreliable guide. Time
can be well spent in studying old
magazines, manuals and circuits, getting an idea of trends and patterns.
Grasp all opportunities to look at collections and displays.
There are several reference books
that are most helpful, and although
they cannot cover every model ever
made, they do provide invaluable background information and are of considerable assistance in identification. Some
useful titles were listed in this column for
July 1993.
Start with a close look at the cabinet.
Its condition will not always reflect the
state of the chassis, but if the finish is in
good condition, and original, the chances
are that the mechanical condition of the
chassis will be reasonable. First off
though, are the tuning knobs all there, do
they match and are they original?
Look carefully at the cabinet finish. A
popular but misguided trick is to 'freshen
it up' by slapping some polyurethane
over the original nitrocellulose lacquer.
This 'toffee apple' treatment is obvious in
a good light, and can only be remedied
with a complete refinishing. A few
scratches and bruises are inevitable, but
look out for missing patches of veneer,
structural damage and glue failure. Water
damage can cause veneer to disintegrate
and bubble. Very early console sets were
often on legs, and these may have at
some time been shortened.
Insect holes can be an unsightly problem. Borer eggs are usually laid in a hidden area of bare wood, including the
entrances to old holes, but the adult
beetle can emerge through a visible
polished surface: A few holes can be
coped with, but look carefully at the
edges of plywood for heavy infestation,
which could spell real trouble with the
cabinet eventually disintegrating.
A warning~ borer may still be active,
and ready to colonise other cabinets. So
as a precaution upon acquisition, the interior of a cabinet should always be treated
promptly with a methyl chloride solution
or similar borer treatment.
Problem holes
Man-made holes added to cabinets
are often a greater problem, as they are
bigger. Extension speaker and pickup
sockets and switches were popular additions to the sides of cabinets, and are
difficult to disguise. Worse are holes
made for additional control shafts, as in
the case of our Atwater Kent. To make
matters worse, these are usually in the
front of the cabinet, and require very
skilled workmanship if they are to be
completely disguised.
A very visible modification popular
during the late 1930's was the 'updating'
of receivers by the fitting of magic eye
tuning indicators. This entailed cutting
large holes in a most visible part of the
cabinet. Sticklers for accuracy will say
that such additions should be removed,
but often repairs are so difficult that this
modification has to be lived with - although it could well have an adverse effect on the value of the receiver.
These comments have applied to
It is obvious that this
Model 80 chassis has
been considerably
modified, with the
removal of many of the
unique Atwater Kent
components. There is
also an extra shaft
belonging to an added
wavechange switch,
requiring a fourth hole
to be drilled in the front
of the cabinet. Note the
warning sign of
overheating, in a run of
burnt wax between the
right hand shaft and the
transformer cover.
ELECTRONICS Australia, February 1995
99
VINTAGE RADIO
wooden cabinets, but many were made of
brittle plastic and should be checked
carefully for cracks and missing pieces.
Repairs can be very difficult to conceal.
Cabinet condition will be fairly obvious, but evaluating the condition of the
contents can be a minefield. Modifications, repairs and alterations vary in the
degree to which they can be remedied.
Some will be the result of standard servicing and can be readily corrected, but at
the other end of the scale is the degree of
butchery suffered by the Atwater Kent.
Remember too lthat sometimes a
receiver with a fine cabinet was
'upgraded' by ripping out the original
contents and replacing them with a
newer, chassis.
.
An important component is the
loudspeaker. Many prewar sets used
speakers with electromagnetic fields, but
it is common to find a modem per-
manent magnet field replacement.
Apart from its non originality, this will
have entailed modifications to the filtering system.
One popular technique by servicemen
when fitting a PM replacement speaker
was to retain the original field magnet
and winding for filtering and tuck them
inside the cabinet somewhere. But more
commonly, a high wattage resistor of the
same value as the original field was
fitted, with an extra filter capacitor. Don't
overlook possible damage to the speaker.
With the front of the cabinet facing a
window, it should not be possible to see
daylight through the cone!
Missing valves
If at all possible,· and especially if a
valuable radio is involved, endeavour to
look under the chassis. After all, we look
in the motor compartment of a car or the
1
foundations of a house we are buying.
Admittedly this may not be practical at
auctions and yard sales, but for a leisurely private sale, it should not· be an unreasonable request. While the chassis is
out, look on the floor of the cabinet for
puddles of congealed wax, which can be
a warning of power transformer overheating. Check for missing valves, which although not always an insurmountable
problem, can involve extra expense. Although American and Australian types
are not so difficult to find, early Philips
and European valves are now very
scarce. Are all the shields present?
Authentic replacements are frequently in
short supply.
Valves can be a very useful in determining age. Briefly, and as a guide, the
2.5 volt and 4.0 volt heater valves were
little used after 1935. In general, 6.3 volt
heaters and bases with thick pins were
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For readers interested in the 'A.K. Way', here is the circuit of the model 80, using the then newly introduced variable-mu
type '35 tetrode. Note the use of their own resistor colour code, which had no logical pattern at all. There Is also the 'double
spot trimmer' circuit for reducing Image signals, a problem with the low IF frequency of 130kHz.
100
ELECTRONICS Australia, February 1995
ommon between the mid 1930's and
arly 1940's. Octal valves were used inreasingly after about 1936, and miniac1re valves will be found only in post
Vorld War Il receivers.
The chassis may be authentic, but what
1bout its condition? Apart from its un;ightly appearance, extensive rust can be
t clue to potential problems. Patches of
:orrosion can be from rodent deposits,
1Vhereas general rust indicates that the
·adio has been stored in a damp environnent and that various components may
iave suffered. This can vary from soggy
:peaker cones to corroded coil windings.
;crewheads
Important clues suggesting substituions or modifications can come from the
1resence of screws. It was standard pracice to rivet valve sockets and small com1onents to the chassis. Be on the lookout
herefore for screw heads - especially if
mplated, the wrong size, or very shiny.
\t the same time, empty holes in a chas:is may indicate removal of parts.
A very common modification is sub;titution of the power transformer. Apart
'rom the obvious appearance problem
;reated, unless the voltage rating of the
mbstitute is correct, operating voltages
;an be very different.
Recently I encountered a set where
the power transformer replacement
plus the use of silicon diodes meant
that the actual high tension was 350
volts instead of the correct 225 volts.
This sort of treatment does nothing to
enhance the longevity of valves and
components. In many respects, it is
better to have an original burnt-out
transformer than a substitute that is
working, for the original can be
rewound to provide the correct
operating voltages and appearance.
Dials are very visible and there are a
number of things to watch for. Older
scales were not protected by glass and
strangely enough, often were printed with
water-soluble ink, making them very difficult to clean. Glass scales may be
chipped or broken. The tuning knob
should turn freely, without slipping, and
the pointer should move correspondingly
and smoothly.
Later sets will have cord driven dials,
which commonly need restringing. Dials
from the 1930's were often driven on the
rim of a large diameter disc. Be alert for
wear on the edge of disk and pulley,
causing the drive to slip.
I hope that these hints will be of help in
avoiding some of tile problems which
may be encountered when buying an old
EXPERIMENTING WITH ELECTRONICS
Continued from page 92
In· our electronic version, in Fig.5,
Cl and IC2 both have their own oscilator circuit and pushbutton. The output
lisplay is four LEDs per IC, from the
irst four available outputs of each IC.
N'hen PB 1 is pressed, counter IC 1
:ycles, and LEDs 1 to 4 pulse on and
>ff. When the button is released, the
lisplay stops at a random value. The
;ame applies to IC2.
We could leave the game there, in
which each player presses a button in
Hi-tech Cinemas
Continuefrom page 25
This cue brings the house lights up to
preset level. Then eight seconds before
the end .of the credits, another cue initiates the Auto-stop sequence (see
above). All that has to be done now is
clean the projector and prepare everything for the next show. The computer is
left to start the'next screening, at the
time setting in its program.
It's interesting to show a projectionist
of the 'old school' how a modern
receiver. It takes only a short while to
carry out the checks, but they are essential if mistakes are to be avoided.
Finally, don't be put off by the horror
stories. Most transactions are much more
successful than the one I have described,
and end with satisfaction for all concerned.•)
.
Audio - Radio ~
1IValves
& H'ware I
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New shipment power &
pre-amp valves sockets i
i retainers etc. Send SAE !
for free price/info list.
1
~l Also: parts circuits data !
··j sheets technical advice l
& cu~tom construction. 1
l Repairs to all valve i
l equipment.
1
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turn, with both players ready to shout
'snap' when the two displays are the
same. But we need a bit more sophistication, which is provided here by the
circuit around Q 1.
If PB2 is pressed, C2 charges directly
from the supply, and transistor Ql is
turned on, held on by the charge in C2
when PB2 is released. This lights
LED9, and forward biases isolating
diodes D2 and D3.
As a result, the clock terminals of
both ICs are pulled low, inhibiting further counting. The displays are there-
fore frozen, and PB 1 and PB3 are effectively locked out of operation.
After about five seconds, C2 discharges, Q 1 turns off and LED9 goes out.
The clock inputs to the counters are
now enabled, so the game can continue.
The main purpose of LED9 is to show
.the players that PB2 has been pressed.
The delay stops the other player from
robbing you of your win, as the display
is frozen for at least five seconds. Also,
there's enough time to confirm the button has been pressed when there really
was a win.
Have some fun with these simple
games circuits! +
automated theatre works. They cannot
get used to walking away from the
equipment and letting it run on its own ...
On my holidays last year in
Britain, I saw a projection system using
an endless loop platter, allowing a show
to be repeated all day unattended. The
only reason for someone to be attendance is in the case of a breakdown.
This system was at the Museum of the
Moving Image, on the South Bank in
London.
That is another story, but the Museum
is well worth visiting by anyone interested in cinema, who is in London on
holidays.
That's the end of my story, which I
hope has brought you right up to the
present in terms of the technology in use
at your local cinema.
POST SCRIPT: The Xenon lamp
mentioned earlier in this article was
finally removed from service at
6046 hours.
The average life of this size Xenon is approximately 1500 hours. Although the
lamp was still working, the arc was becoming unstable with the possibility of
the lamp exploding
causing damage
to the reflecting mirror - and a replacement mirror costs in the order of
$1500! +
and
ELECTRONICS Australia, February 1995
101
ADVERTISING RATES
FOR THIS PAGE
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Unusual Books:
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SMALL ADS: The minimum acceptable
size of two centimetres x one column costs
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CLASSIFIEDS: $4 for 40 letters. Just
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CLOSING DATE: Ads may be accepted
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PAYMENT: Payment by cheque or
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THE ADVERTISING PRODUCTION
MANAGER
ELECTRONICS AUSTRALIA,
P.O. BOX 199,
ALEXANDRIA, NSW 2015
68705 Development System:
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Phone (02) 541 0310 Fax (02) 541
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Kit Assembly & Repair:
Low Rates. Contact Autronics on
Phone (08) 294 8591.
Surplus Enclosures For Sale:
Betacom Aluminium Instrument Cases
- with chassis & sub-panel. Half rack
and full rack widths 1, 2, 3 and 4 units
high. Top quality, in original unassembled packs. From $42. Lockable moisture and dustproot steel cabinets with
gear plate, painted brown and beige
from $80. For list of available sizes,
prices and quantities, phone (02) 533
3322 or fax (02) 534 6360.
Digital Pulse Generator:
Kits for this project ($95.00 + $4.00
p&p) as described in EA Dec 94/Jan
95 are available from Digital Logic
Systems, PO Box 647, Elizabeth, SA
5112. Phone: (08) 255 2953.
Stock Clearance Bargains:
61 Line plug 7 pole DIN 45329 grey
270 degr $35, 34 Line socket 5 pole
DIN 43529 black 180 degr. $20, 20 YAdaptor DIN 5 pole 180 degr.
male/2female$45, 85 Connector 9 pole
D sub female solder $80, 69 Shells
DB25 grey plastic high quality $70, 15
Shells DB25 grey plastic simple $10,
13 Phone Adaptor Modular/Austr.
(605M) Plug $30, 7 Phone Adaptor
Modular/Austr.(610M) Socket $20, 200
clear PVC boxes with lid 32x66x16mm
$35, 80 Grey PVC multi purp. boxes 2
snap halves 124x71 x30mm $50 70
Panels with 12 PCBs each
1•TC74HC04 DIP14 new $250 (PCB
size 25x25x1 .7mm fits in DB 25 shell),
or $500 the lot, Phone (09) 446 8521,
Fax (09) 446 7419, TSE Electronics.
"The Homebuilt Dynamo":
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A$85 postpaid airmail from Al Forbes,
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anytime. Phillips Ferroxdure rotor
magnets (3700 gauss) kit now available cut to size and magnetised. Fax:
(0011) 649 818 8890.
Amidon Ferromagnetic Cores:
For all RF applications. Send business
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Imports, Box 431, Kiama NSW 2533.
Agencies at Geoff Wood Electronics,
Sydney; Webb Electronics, Albury;
Assoc TV Service, Hobart; Truscotts
Electronic World, Melbourne and
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Don's Short Form Kits:
PIC16C54-58/71/84 Universal PCB
$23, Basic Stamps $65, Serial Driven
18 110 $70, Parallel Driven 64 110 $38,
RELAYS PCB $10-$20, zao Dev. $38$52, 8K-4Mb Print Butt. $38-$52.
Promo Disk for all projects $2. Don
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Tullamarine 3043.
'
Tender Estate Military Radios:
Military
Pamphlets
Amateur
Transceivers
Li nears
PS Us
Genemotors General. Catalogue 85c
stamp. Hadgraft 17 Paxton St Holland
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i-~.(C. ~. UAJJJI0 )~Tl'. L·i:'~~ i
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Phone (07) 245 2008
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Tiny Video Cameras $20 off!
This month from $179. Previous buyers get DOUBLE $40 off.
MATCHBOX SIZE PCB MODULES
from 32x32x23mm with lens. 16
Types. Optional Lenses, C Lens
Mounts, Cases & Technical Manuals.
See review P138 EA Nov '94.
All THINGS Ph/Fax (09) 3499413
Laser Tubes:
Systems and parts "garage sale".
LASERVISION, Australia's Largest
Laser system manufacturer is selling
equipment to make way for new models. Please contact Stephanie for a list
of items available. Ph: (02) 651 1511.
POSITION VACANT
Electronics Technician:
A Technician is required to perform
through-hole component-level repairs
in our well equipped work-shop in
North Ryde. Minimum tertiary requirements are the electronics and
Communications Trade Technicians
Certificate or equivalent and three
years component level repair experience. Switchmode Power Supplies
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Written applications should be
addressed to :
The Manager,
SWITCHMODE Power Supplies Pty.Ltd.
P.0 Box 14, North Ryde, 2113.
VALVES
6AV6
6N8
6CM5
$10
$10
$10
S<CllLIO> <Cl(JJ)"lr
6BD7
6AU6
6BA6
6BL8
6V4
6BM8
6AQS
6BH5
.5A54
6BHS
EF86
lSS
154
354
1U4
lRS
3V4
$10
$10
$10
$7
$8
$8
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
$10
WANTED
AR-3000A:
Rolls Royce of scanners. As new. Still
in box. $1590. Phone: (066) 42.5263:
Business for sale:
vintage electronic repair business specialising in vintage radio. Est. 1988
and includes huge stock of spares
including 10,000 valves and over
140,000 high voltage caps. This business with established turnover and
much potential is offered with lease or
freehold option. Enquiries to Ph: (060)
244 558.
AT LAST!:
A new book on Crystal sets. "Crystal
Sets 'N' Such" 150 fascinating pages.
See "Book Review" this issue. $19.95
Incl P&P in Aust. R.J.Young - R.M.B
1561. Benalla. VIC. 3673.
Sell and Forward very old radios:
valves, crystal sets, test equip. R&H
magazines etc. Ph: (07) 356 6052.
Obsolete MICROBEE COMPUTERS:
for re-incarnation as pre schooler
teaching aids. Freight will gratefully
be paid. Contact Jeff Lee, 54 Princes
Hwy, Cobargo, Phone (064) 93-6669,
Fax (064) 93-6530.
Manual Circuit for Daton VCT-V:
Valve tester. Will cover all costs. David
Aberdeen P.O Box 171 Kyogle 2474.
Ph: (066) 333 190.
Any early valve hifi, Quad, Leak
Garrard 301/401, SME, Ortofon, KT66,
KT88, 3008 or similar. Cash paid 015
585179.
Handbook/Data for visual alignment
SIG/GEN made by Ratcliffe Eastwood
I NSW (DCA ldent Y10/35) (Model
203). Phone (054) 41 1197. Also,
valves available - see my ad in
Aug/Oct Marketplace.
DISCOVERING VINTAGE RADIO
Enjoy reading about vintage radio ?
If so, you'll enjoy reading Peter Lankshear's new book. We've collected
together 34 of his most popular articles on the subject, and reprinted them
to form a highly readable h:itroduction to this fascinating subject.
Now available for only $4.95 from your newsagent - or by
mail from Federal Publishing, PO Box 199, Alexandria 2015.
If ordering by mall, add $2 to cover packing and post.
IF 1RANSFORMERS
FOR VALVE
RADIOS $3
POWER
TRANSFORMERS
240V
$10
12V
$10
28V
$10
TFST PRODS AND
LEADS $2
FERRITE TUNERS
SPECIAL COVERS
AUSTRALIAN AM
BANDS 10
SPECIAL
ROTARYPOTS
MIXED 25 TYPES $20
TAG STRIPS OLD
STYLE MIXED
10 FOR $2
50 and 25 years ago...
'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.
February 1945
Electronic headquarters: General
Electric announced the purchase of a
155 acre plot in Liverpool, five miles
from the city of Syracuse, New York, on
which they plan to build a new plant
and make it the headquarters for the
company's electronics department.
Preliminary arrangements call for the
erection of several buildings so
landscaped that it has been suggested
the plant be called 'Electronics Park.'
Luxury airliner: The most modern
luxury airliner in England, bearing the
anns of the Duke of Gloucester, rests on
an airfield near Manchester, says the
'Daily Mail'.
It is a four engined-Avro-York, specially built for the use of the Duke and
Duchess of Gloucester in Australia. It
will leave England for Australia soon to
await their arrival.
The airliner contains a stateroom
upholstered in red leather, from which
the Duke will be able to maintain constant communication with the ground, a
rest room and sleeping quarters with
thick pile carpets, an ultra-modem tiled
bathroom and individual saloons for
equerries and ladies-in-waiting.
February 1970
Atomic battery on the moon: The
Apollo 12 experiments left on the
moon's surface by the lunar mission
will be kept functioning for at least a
year with electricity developed by a
nuclear electric power system.
Called SNAP-27, it is one of a series
of radioisotope thermoelectric gener-
ators (or atomic batteries) developed by
the USA's Atomic Energy Commission
under its SNAP program. The lunar
device was developed as part of a program directed at the development of
generators and reactors for use in space,
on land, and in the sea. It is designed
to provide all the electricity for continuous one year operation of the NASA
Apollo Lunar Surface Experiments
Package. This is the array of scientific
instruments and supporting subsystems
deployed by the Apollo 12 astronauts on
the lunar surface.
The radioactive isotope chosen for the
SNAP-27 fuel was plutonium 238. It is
very long lasting, and at the end of 90
years will still be delivering half of its
original heat.
Electric powered vehicles: A battery
powered electric car, used for mail collection at Mascot Airport, Sydney, is the
first of a range of Westinghouse (USA)
vehicles to be marketed in Australia.
Initially they will be imported but
Australian manufacture is planned. The
two passenger vehicle on loan to Ansett
Airlines, covers about 15 miles daily in
intermittent stop-start service between
lam and llpm, with overnight battery
charging. +
EA CROSSWORD
ACROSS
1. Major software brand. (9)
6. Construct. (5)
9. Johnson noise is equivalent
to -- noise. (7)
10. Following in phase. (7)
11. Title bestowed on
Rutherford. (4)12. Device invented by
De Forest. (5)
13. Aerodynamic force. {4)
16. Said of wave of about 1MHz. (6)
SOWTIONFOR
JANUARY 1995
SC RA MB LIE•F LY BYS
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.
,
...
104
....
17. Most dense element (6)
20. Type of antenna. (6)
21. Combined recordings. (6)
24. Composition. (4)
25. Gulde objecfs path. (5)
26. Flashovers. (4)
30. Semiconducting
element. (7)
31. Inverting device. (3,4)
32. Reduced in inlensity. (5)
33. Telecom communication
service. (9)
DOWN
1. Initial part of MOSffi. (5)
2. Removed displayed
data. (7)
3. 8ectrical units. (4)
4. Container for
lubricant. (6)
5. Show on lV (8)
6. Faulls In equipment. (4)
7. Element discovered by
Tennant in 1803, (7)
8. Brand of compuler and
allied hardware. (8)
14. Transfers data to backing
store. (5)
.
15. Problem in computer
ELECTRONICS Australia, February 1995
program. (5)
18. Metal used in resistance
thernometry. (8)
19. Floating wreckage. (7)
20. Pair of associated
spectral lines. (7)
22. An advantageous
purchase.(7)
23. Interface of handheld
outdated recorder! (3-3)
27. Perform soldering
process. (5)
28. Electrolyte in a
simple cell. (4)
29. Acronym for short runway
potential. (4)
Electronics Australia's
Professional
Electronics
S • U • P • P • L • E • M• E• N• T
NEW HEWLETT·PACKARD HP 54620A 'AFFORDABLE' LOGIC
ANALYSER OFFERS 16 INPUT CHANNELS, SAMPLING AT UP TO
SOOMS/SEC, PLUS THE SAME EASE OF USE AS THE COMPANY'S
POPULAR 54600·SERIES DIGITAL SCOPES •••
NEWS HIGHLIGHTS
performance downconverters for use as
part of consumer receiving systems, and
a variety of associated equipment.
The MDS transmitters include both
Brisbane based microwave technology specialist Mitec Limited, recently fixed frequency and 'agile' models, with
floated as a public company, has power output capabilities of lOW, SOW
launched a range of MDS (microwave and lOOW. Fully designed and manufacdistribution system) products designed tured in Australia using the latest
specifically for the Australian pay-TV' GaAsFET devices, the transmitters inmarket. The product range includes corporate digital AGC loops to maintain
professional transmitters for use in output power level, are 100% protected
urban MDS signal distribution, high against excessive output VSWR and
feature microprocessor-based diagnostic
and control systems.
The domestic downconverters are
based on a common 'Wavecatcher'
module which integrates a low-loss
dipole antenna with a front end offering
1.5dB noise figure and 30dB gain. Other
features include low power consumption, low phase noise ('digital ready')
and high performance filter circuits to
cope with Australia's two separate MDS
bands (one close to the frequency used
by microwave ovens). The module can
be integrated with four different types of
microwave antenna, providing effective
gains of +6dB, + 12dB, + 18dB and
+24dB respectively. Its end-user cost is
expected to be around $250.
Even before the formal launch of the
products, Mitec received its first order
from pay-TV firm Australis Media.
Our picture shows Peter Harle (right)
explaining BBS operation to EA technical editor Rob Evans.
The new Electronics Australia BBS
can be called on (02) 353 0627, with
your modem set for 300, 1200 or
2400bps full duplex operation and a
data format of '8-N-1' (eight data bits,
no parity and one stop bit). We're trialling a version of the 'Ezycom' BBS
management program written in
Australia by Peter Davies, so it's all
quite friendly and self explanatory.
Our current plan is to have the BBS
active between 7.00am and 2.00am each
day/night, and off-line from 2.00am to
7.OOam. So feel free to call it up, and
avail yourself of the information.
By the way Peter Harle's Mt Druitt
TAPE BBS also has material of interest
to electronics people. You can call it on
(02) 839 1310.
MITEC EQUIPMENT
FOR AUST PAY·TY
COMPUTER BBS
FOR EA READERS
Electronics Australia is now able to
offer its readers the convenience of a
computer bulletin board system, thanks
to the generous assistance of Peter
Harle, Head Teacher of Industrial
Electronics and Electrical Engineering
at Mount Druitt College of TAFE.
Set up in response to requests from
many of our readers, the new BBS
makes available for downloading
software and firmware for our published
projects, along with files which duplicate our current project index and will
therefore assist readers in locating any
particular article. We're also planning to
make available 'last minute' project information, plus any other electronics-related shareware and public domain
software we believe you'll find useful.
We're very grateful to Peter Harle's
help in setting up the BBS, because
Peter is much more experienced in
doing this than we are. He's the 'sysop'
(system operator) of the very successful
Mt Druitt TAFE Information Service
BBS, which in fact he set up some time
ago, and for the time being he's also acting as our own BBS sysop until we
gain enough experience to 'go it alone'.
106
ELECTRONICS Australia, February 1995
CENTRAL COAST
AMATEUR FIELD DAY
The Central Coast Amateur Radio
Club's Annual Field Day, regarded by
many as the premier event for amateur
radio in Australia, will be held on Sunday February 26 at Wyong Racecourse,
Howarth Street Wyong (a five-minute
walk from Wyong station). The Field
Day has become justly famous, and in
previous years many amateurs and
electronics/computer hobbyists have
travelled interstate in order to attend.
Traditional events include stands and
displays by all major amateur radio
equipment suppliers, and many suppliers of general electronic equipment
and components; lectures on topical
technical subjects; amateur TV, satellite TV and packet radio demonstrations; a 'flea market' and car boot
sale of unwanted equipment; a radio
'fox hunt'; and stands providing information on the activities of the WIA,
WICEN, ALARA etc.
Admission to the event is $8 for
adults, seniors and pensioners $5 and
children under 12 free. The gates open
at 8.30am. Further information is available from the CCARC, PO Box 252,
Gosford 2250 or phone (043) 40 2500.
Yamaha Music Australia has delivered two all-digital audio post production
Systems to AA V Australia in Melbourne. The systems comprise hard disk
based audio DSP workstations, integrated with Yamaha DMC1000
automated digital mixing consoles.
INNOVATIVE
'SHOWER TIMER'
Australian engineer David Whitby,
well known for his inventions such
as an energy-saving compact fluorescent lamp ballast and a telephone
protection device, has developed a new
product known as the Gum Leaf Shower
Timer ST4.
Designed to help consumers conserve
water and also save on their water and
energy bills, the ST4 is a compact
waterproof timer which mounts inside a
shower recess and times shower use. At
the end of four minutes, it emits a series
of loud 'beeps', to remind the shower
user that their water consumption time
has expired. The beeps only stop when
the water is turned off and left off for
one minute.
No user controls are provided, and
operation is fully automatic - the
ST4 senses water use by detecting
the accompanying high frequency
sound emissions.
The ST4 attaches to a tiled wall using
two high quality suction cups. It is
powered by a low cost 9V battery,
which lasts for approximately one year
with average use. RRP of the ST4 is
$34.50 plus $3.90 postage and packing,
and it's available from GumLeafEnergy
'For exceptional research, personal
vision and drive over more than 20
years, including the development of
'Buried Contact Solar Cell Technology',
which is the most successfully commercialised new solar cell technology
developed in the past 15 years.'
Commercial production of the
centre's buried contact solar cells
achieves efficiences of 16 to 18%. This
is appreciably higher than the 11 to 12%
achieved by competing commercial
cells, and is attained at marginal extra
cost per cell, yet results in substantial savings in costs per upit
energy produced and in 'balance ',,of
system' costs.
.
The buried contact technology, which
has been patented by Professor Green
through Unisearch (UNSW's R&D
and technology transfer company), carries several other advantages which
combine to give the cells a decisive
commercial advantage.
In addition, the technology is a major
component in the latest thin film cell
technology design that has been announced by the centre. When it reaches
full scale production, the thin film technology is expected to make solar
electricity cheaper than any present
source of electrical power.
1
Saving Systems, PO 12717 A'Beckett
Street Post Office, Melbourne 3000;
phone (03) 663 7227 or 1 800 628 645,
or fax (03) 663 7202.
NEW HONOUR FOR
PROF. MARTIN GREEN
The contribution to solar energy commercialisation by Professor Martin
Green, Director of UNSW's Centre for
Photovoltaic Devices and Systems, has
again been recognised, this time with a
Clunies Ross National Science and
Technology Award.
The awards are made each year by the
Board of Governors of the Ian Clunies
Ross Memorial Foundation and are for
'excellence in the application of science
and technology.'
The citation for Professor Green read:
NEW MAGAZINE
A new publication has joined EA and
its fellow titles at Federal Publishing
Company: Good Planet, directed at
young people with an interest in ecology, energy conservation and reduction
in pollution.
ELECTRONICS Australia, February 1995
107
NEWS BRIEFS
NEWS HIGHLIGHTS
The new publication takes a
deliberately offbeat and 'informal' approach, with liberal use of cartoons,
humour and a bright, colourful layout.
At the same time the articles are informative, and designed to raise reader
awareness of the factors which determine global 'health', and how problems
can be addressed.
Good Planet is available at newsagents now, priced at $4.95.
• The 13th Microelectronics Conference will be held in the Adelaide Hilton, Adelaide SA, July
16-19 1995. For more information contact the IREE Society, PO Box 79, Edgecliff 2027; phone
(02) 327 4822.
• St Lucia Electronics has been appointed Australian Distributors for Chemtronics of Georgia,
USA. Included in the product range are Chem-wik and Chem-wik Lite desoldering braids.
• Independent Information Technology Training is running a LAN Design and Implementation
course in Sydney from 29- 31 May; Melbourne from 5-7 June, and Brisbane 1-3 March 1995.
For more information phone (02) 252 2844.
• Dr Rowan Gilmore has been appointed by SITA as the Sydney-based Regional Technical and
Operations Director for Australasia and the South Pacific.
• Switch mode power supply manufacturer Amtex Electronics has been formed into two
separate divisions: Power Supplies and Displays & Systems.
• Geoffrey Smith, formerly Manager Strategic Technology at Optus Communications has joined
Scientific-Atlanta Australia.
THAI PARTNER FOR
PRECISION POWER
Australian power line filter
specialist Precision Power, based in
Brisbane, has signed an agreement
with Thailand firm Encorp, whereby
the latter will manufacture and market
25TH ANNIVERSARY OF
TAIT ELECTRONICS
Tait Electronics, which is now
celebrating its 25th anniversary, has
grown from a small organisation with
a core staff of 12 to a major international company with 700 employees in
22 offices around the world.
The New Zealand headquartered
company has become one of the
world's three largest manufacturers
of two way mobile radio systems,
with an annual turnover of more than
$100 million.
Tait is a major player in two way
in Thailand the new range of power
line filters which Precision Power
recently launched in Australia. Encorp
has been an agent for Precision Power
for some five years, and already
manufactures weighing machines and
other electronic equipment.
The agreement is expected to
strengthen considerably Precision
Power's presence in Asia, where
demand for power filtering and conditioning equipment is growing
rapidly. John Wedgewood, the firm's
national sales manager, says the potential is enormous:
"We have to export to developing
radio in Australia, as a supplier of
equipment and a partner in trunking
network joint ventures. Its dynamic
growth is the result of specific
development policies of its owner and
founder, 76 year old Angus Tait.
Angus Tait's involvement in the
mobile radio business has been mainly
motivated by his passion for the technologies and products. In his view,
entrepreneurs whose main objective is
to make money cannot engender a
high level of staff loyalty. Angus considers the primary aim of business
must be some visible, higher objective
that both the owner/entrepreneur and
Mr Angus Tait who owns and guides
the fortunes of Tait Electronics, one
of the world's largest manufacturers
of two way nobile radio systems.
employees see as mutually beneficial
to their futures.
The successful pursuit of these objectives will in time create financial
rewards for both owners and
employees. Tait Electronics' unique
ethos of reinvesting 100% of its profits
back into the business reflects his
business philosophy.
It is appropriate that in the year
Tait Electronics celebrates its 25th
Anniversary, Angus also celebrates
his ?6th birthday, still very actively involved as Chairman and
Afr Angus Tait with one of the first two way mobile radios that he Managing Director in Tait's day
installed in a car.
to day operations.
108
ELECTRONICS Australia, February 1995
countries which are just starting to
develop a power infrastructure. The
grottier the electricity, the better the
type of power filter they need."
Precision Power has manufactured the
US-designed Islatrol power filters for
some years, and has been exporting to
New Zealand, Papua New Guinea,
Malaysia, Singapore, Thailand and
Hong Kong since the 1980's. According
to John Wedgewood the company has
more than 10% of Australia's estimated
$20M power filter market.
AT&T SELECTS MICROCELL
FOR WIRELESS NETWORKS
A novel approach to building intelligent wireless networks for shopping
centres, hospitals, airports and commercial or residential sites has been
developed by Australian company
MicroCell Systems, under a contract
awarded by AT&T.
The 'Mobility Manager' product
will initially support the CT-2 frequency, which uses small, relatively inexpensive mobile telephone handsets.
However, the design is frequency independent, so AT&T and MicroCell are
evaluating the feasibility of supporting
multiple frequencies for Australia and
other countries.
The Project Director of MicroCell
Systems, Aldo Kiamtia, said his company viewed the Mobility Manager
developed contract as a gateway to
AT&T's global market place.
"It's put MicroCell Systems on the
map with the leading world wide communications organisation," Mr Kiamtia
said. "AT&T has given us a great opportunity to let the rest of the world
know what we can do."
MicroCell Systems integrated UK
and US technologies with their application to meet the needs of customers. Mr Kiamtia said the system
incorporated an 'underlying
intelligence' that made it faster and
easier to use than similar products.
EUROPE RECOGNISES
NATA TEST DATA
A recognition agreement signed between Australia's national laboratory accreditation body, NATA, and a major
European laboratory accreditation
cooperation, EAL, will greatly enhance
the acceptability of test data and trade
between Australia and Europe.
The agreement facilitates the recognition of Australia's NATA accredited testing laboratories and reduces the need for
the retesting of many Australian
Yokogawa Austral/a has gained quality assurance approval to 18090011
AS3901, extending to all Yokogawa offices throughout Austral/a and
covering Its range of Instruments, applications engineering and services.
Pictured are Yokogawa's MD Peter Smith and Marketing Director Barry
Mitchell, with the plaque.
products in Europe. In tum, the agreement allows Australian importers of
European goods to accept product test
data from those laboratories in Europe
accredited under EAL (European
Cooperation for Accredi ta ti on of
Laboratories).
NO·REPEATER CABLE
FOR BASS STRAIT
A new world record will shortly be set in a crossing of Bass Strait,
according to Siemens. The record means
that all telecommunications transmissions will travel under the strait without
any amplification on the way - a
whopping 240 kilometres.
"It's a new world record for long
distance transmission," says Dr Ockert
van Zyl, General Manager, Telecommunications and Manufacturing for
Siemens Ltd, in Melbourne. "We
believe we have bettered the previous
world record - set in Denmark - by
nearly 40 kilometres."
Under Siemens' contract with Telstr&,
new, high powered optical amplifiers
will be located on land at Waratah Bay,
on Victoria's south west coast, and at
Jacob's Boat Harbour, on Tasmania's
north western coast. These will give a
mighty boost to all Telstra transmissions
between Tasmania and the mainland via
the new cable.
Eventually all transmissions between
Tasmania and the mainland will be carried by this new link, which will have
18 optical fibre lines. Each line will be
capable of carrying the equivalent of
30,000 voice calls simultaneously.
The new cable connection is due for
completion at the end of May.
The first systems using the new cable
will operate at 622 megabits per second,
managed by Siemens' latest
synchronous digital hierarchy equipment, with the option to upgrade to a 2.5
gigabits per second system later on.
ALCATEL'S BILL
PAGE·HANIFY RETIRES
On December 31st last, Bill PageHanify, AM retired from his position as
Managing Director of Alcatel Australia,
the country's largest designer, manufacturer and exporter of telecommunications technology.
He has become non-executiveChairman of Alcatel Australia, and continues as Chairman of submarine
systems company, Alcatel TCC. He is
also on the board of the parent
company's Alcatel Submarine Systems
group headquartered in Paris.
Mr Page-Hanify began his career with
Alcatel (or STC as it was known then)
as a senior engineer in 1960.
Throughout that time, and especially
over the last 10 years while he has been
Managing Director, he has participated
at senior levels in the remarkable and
rapid transformation of the telecommunications industry, both at home and
overseas, as it has become one of the
world's most advanced and truly global
enterprises. +
ELECTRONICS Australia, February 1995
109
Construction Project:
PC·BASED SERIAL
PROTOCOL ANALYSER
You can do a certain amount of serial data link troubleshooting with a break-out box, but for the really tricky problems you need a protocol analyser. Commercial analysers are vel}' expensive, but the
author has developed a simple, low cost way to do the job with almost any IBM-compatible PC. All
you need is an adaptor cable, and special software he has written ...
by RICK MATTHEWS
There are two tools that any serious
data communications developer or
troubleshooter either has, or wishes
they had: a break-out box and a
protocol analyser. You can use these
tools to monitor Lap Link, XModem,
INTERLNK in DOS 6, serial printer
communications such as Postscript,
data transfers to and from bulletin
boards and E-Mail, serial mice, fax
transmissions, amateur packet radio,
plotters, or anything else that transfers
data through a serial port using the. V24
or RS232 standards.
Generally speaking, break-out boxes
are for observing the electrical signals
on the various handshaking leads on
data links - and, if necessary, rearranging them. Whereas protocol
analysers are used to observe the
actual data that is passing up and down
the link.
These two tools complement one
another; but because the break-out box
is simple and cheap (typically $20 to
$1000) and the protocol analyser is
complex and expensive (typically more
than $20,000), most people have con-
fined themselves to solving those
problems that can be solved with a
break-out box and have abandoned
problems that could have been solved
with a protocol analyser.
The cheap protocol analyser
presented here, while not the fullblown device you would expect to pay
$30,000 for, nevertheless goes a fair
way to help solve those difficult
problems which normally require a
very expensive protocol analyser.
One special benefit of this simple
protocol analyser is that it is much
The author viewing his protocol analyser software on the right hand PC, monitoring a link running on the left hand PC.
110
ELECTRONICS Australia, February 1995
Above: The kind of adaptor cable needed for the protocol
analyser. At left are the connectors for the actual data /Ink.
Right: A close up of the PC screen when the protocol
analyser software was monitoring a Lap Link data transfer.
easier to set up. At least you do not
have to go through a galaxy of complex, time consuming and error-prone
set up procedures every time you use it.
Because this protocol analyser works
with asynchronous serial data circuits
using the RS-232 and V24 hardware
and signalling standards, it covers most
serial data communications situations
these days anyway.
What you need
the mother board. The jumpers connect
IRQ4 to COMl, IRQ3 to COM2, and
often connect OUTl and/or OUT2 from
each of the SIO chips to a tri-state gate
to complete the interrupt paths to the
adaptor bus.
These jumpers are usually intact
when the PC is sold new, but could
have been removed to allow IRQ3
and IRQ4 to be used for other cards
such as tape backup or sound cards.
Jumper errors are more 11.kely than anything else to prevent the protocol
analyser from working.
choose DB25 (25 pin) or DB9 (9 pin)
plugs and sockets, for the connections to the data link under test. Since
both standards are used without any
real rules, you may need a lot of 25 to
9 pin converters - or a lot of alternative cables.
I have used 25-pin connectors
throughout except the female socket
that plugs into COMl on the protocol
analyser PC. This suits most desktop
PCs. Portables tend to use DB9 connectors for both COMl and COM2 while
XTs often use only DB25 connectors.
All you need is a PC, the adaptor cables as shown, and the software.
The PC can be anything from a PenThe display
tium to, in some cases, even an XT. The cables
Both COMl and COM2 must be
The cabling provides a straight
The screen display shows data flowpresent and working.
through connection for the serial ing in real time, with a blue back- ·
You only need about an hour in most link being monitored, and a con- ground for one direction and a red
cases to collect the data you want, so a nection to the receive data inputs on background for the other. All ASCII
borrowed PC will do. If you make on- COMl and COM2 of the protocol printed characters are shown normally,
site visits for maintenance purposes you analyser PC as shown in the diagram. while all control characters are shown
probably carry a portable PC for main- Interference to the link being monitored prefixed with a circumflex (") followed
tenance anyway, so you may only need will be minimal.
by the ASCII character formed by adto carry the extra cables - which is a
There is just a bit of extra load- ding 40 hex to it (i.e., a carriage return
lot better than carrying a protocol ing on the receive and transmit data is shown as "M, and a line feed is
analyser everywhere 'just in case'!
leads. All other handshaking leads shown as "J, etc.).
The analyser uses standard data rates, are unaffected.
The display is 80 characters across
with the upper limit being determined
The only other problem you will the screen by 25 lines down, without
by the speed of the PC and the SIO have with the cables is whether to any formatting. The carriage returns,
chips used for its COMl
linefeeds, backspaces, tabs,
and COM2 ports. A Penetc., are prevented by the
tium or 486DX with
software from operating norNS16550 SIO chips (or
mally. Those control chartheir equivalent) should
acters just appear in
work up to 115.2K bits/
sequence in the current line
second, whereas an XT with
as "M, "J, etc. Other protocol
8250 SIO chips will
analysers use this or a similar
probably be limited to
method of display as a stand9600b/s.
ard option.
There are some jumpers
The data is saved in the
that must be properly inanalyser's buffer using one
stalled on the PC's 1/0 card,
byte per character, with each
to allow the use of intercharacter stored as 7-bit
rupts on COMl and COM2.
ASCII with the most sigThe connections required for the protocol analyser's
In most portables and a few
nificant bit used to indicate
adaptor cable. Either 0825 or 089 connectors can be used
PC's, these jumpers are on
data direction. The upper bit
as desired, to suit your computers...
ELECTRONICS Australia, February 1995
111
-PC-based Serial Protocol Analyser
is set for data flowing in one
direction and cleared for the other
direction. If you want to capture a full
eight bits per character in either or both
directions, you will have to modify the
program to store the direction information - in, say, an additional byte to
make two bytes per received character
in the buffer.
Circular buffer
COMl and COM2 on the protocol
analyser PC are interrupt driven, saving
their data in a 64KB circular buffer.
Polling the SIO ports would be simply
too slow. The circular buffer saves up
to the last 64KB of data, which can be
written to a file for later analysis (not
shown in the listing). 64KB is chosen
as a reasonably large but realistic value
for analysis, yet allows the analyser to
run indefinitely without the risk of
overflow. This is handy for catching
those infrequent intermittents, that need
long monitoring periods'.
The software
The software has all been written in
Microsoft's Quick C, version 2.5. There
are a few non-ANSI functions used, so
the code may not be completely portable to other compilers; but most of it
should be. The key to success is the
proper use of interrupts. SIO interrupts
Another view of the protocol analyser running on the right hand PC, monitoring
a data transfer using Lap Link to the left hand PC.
5. tum the SIO chips' OUTl, OUT2,
and handshaking on
6. enable the SIO chips' receive
interrupts
7. unmask the ?fOgrarnmable interrupt
controller's SIO interrupts
When an interrupt occurs from either
CO Ml. or COM2, the programmable
interrupt controller handles it virtually
immediately except if some higher
are not well described in most references. The sequence I use for setting up
these interrupts is:
1. disable the SIO chips' interrupts
2. write the interrupt routine .addresses
into the correct low memory
locations
3. set the SIO chips' data rates, bits per
character, parity, and stop bits
4. set the circular buffer pointers
,......................................................
OOTAll - •rot.ocol AD•lY••r u•inq a PC.
JUJ'l'BOR1 Riot xattheva, U•lai4e, south Auatralia.
printf ( 11 \DPROTOCOL AnLY8BR lliainq COJl1 and COll2 r \n\n"
"%• Baud, 8 bita no-parity, or 7 bita odd or even parity, 11
"and 1 atop bit. \n."
11
(U•e function key 'P10' to exit)\n\n"
"Bit any key to proceed . • • 11 ,arqv[l));
9etoh(Ch) i
***************
****** **** ** *** * ** ** * ** *** *** ***•••*****I
#inclu4a <at4io. h>
#include cbiO•· 11.>
#iDolwl• cqr•ph. h>
1pra911& obaoll:JIOint.r (off I
HtYideo-d•( TUTCIO);
#4efiH COlll 0
:vrapon(_na.rJIO•>; /* end-of-line wrap
#define COll2 1
i
end-of-aoreen aoroll OB *I
#defiH BLUB 1
ld•fiH UD •
unaiped obar far •p;
uaeip•4 char tar •cu
unaiqaad 4at1•0X3:fa, iarl•OX3ft, aor1=os3to, l1r1=0x3fd; /* COJl1 */
u•i;ned datz:os2f1, ier2:os2ft, aor2=os2to, lar2=ox2td; /* co112 */
u•i9ned ;1aaak•Os21, piotrl•Ox20, eoi:ox20;
l'ILS *fo;
· Ollitp(ierl,O);
/* diaabl• s~o interrllipta •/
_4oa_aetvect(1Z, aioint1); /* aat int vector 12 (IRQ4 uaed by COX1) •/
outpu,ar2,0);
do• -aetveot(ll, aiointZ); /* a•t int vector 11 (IRQ3 uaed by COXZ) */
ilato.-= t_COJl_Clllll I _COlf_ITOP1 I _cox_•OPllITY I baud_ratal 1
bioa aerialooa( cox IllIT, COll1, data);
:bioa:aerialooac:cox:I:nT, 00112, data);'
/***********•*********** IlfTBRRUPT
HUDLBRS **********************/
void interrupt aioint1 ()
/ * .interrupt roll.tin• *I
{ •p++ = inp(dat1) 1 Os7f; /* ;et th• data, clear 1188 and ator• it */
outp(ier1,1)1
/* r•••t SIC interrqpt •/
outp(piotr1,·eoi);
/* reaet interrupt contoller */
void interrllipt aioint2()
( •p++ = inp(dat2) I OXIO;
ollitp(ierZ,1);
ollitp (piotrl, eoi) ;
/*
/*
/*
/*
/****************************
aain(int ar;c, char ••arqv)
/* uae th• oxaooo aegaent aa a oiroular buffer */
p=q=(ohar tar •Joxaooooooa;
outp(•orl.,OXf);
,. turn on RTS, DTR, /OUT1, /OUT2 */
outp(marl,OXf);
,. turn Oil RT8, DTR, /OUTl, /OVT2 .,
outp(ierl. 1 1);
/* enable ax interrupt */
outp(ier1,1>;
/* enable ax interrupt •/
outp(piaa•k, (inp(piaaak) I oxe7)); /* unma•k BIO interrupt• */
in.terrllipt roll.tin• */
qet th• data, ••t MBB and ator• it */
r•••t BIO interrllipt •/
reaet interrupt oontoller *I
llAIJf
vbil•(1)
{ if (pl=q)
( olla•q++;
if(oh & OXIO)
******************************/
(
{ unaiqn•d char dat.a;
unaiped char ah;
char atr[2]s{ 11 11 ) ; /* atrinq for _ollittext f'llinotion */
char oon.[2]•{" ... "); /* •trinq for control-char ayabol */
int rate, ballid_rate;
int i;
if(arqo c 2)
( printf ("Protoool l\naly••r
uit 11) I
U••9•
}
_outtezt(atr);
i f ( bioa lteybr4 ( ltBYBRD RllADY)}
{ i f ( ( i ; bio• ieybr4(-J:lllfBRD RIW>)) =.OXUOO) , . f10 k•y? . ,
{ outp(•ir1,0);
outp(ierl,O);
outp(llOrZ,O);
, outp(ierZ,O) 1
break;
!aoanf (arCJY[l] ,"'4", 'rate);
:•!:::'~;::!
uit(l) I
112
ELECTRONICS Australia, February i995
/* print a ohar with background colour */
}
i•a PROTAB <bau4_rate>\n11 ) ;
baud rate a CON 1200; break; /*(fill in otb•ra·•• needed)•/
o••• t1001 ~au4-rate = -cc»Ct100; br9ak;
4efault1
printf ("lfot i valid Baud rate I \n");
aet!:tkoolor(RllD); el•• aetbkoolor(BLVll' •
outtu:t(aon);
itr[O] += •t•; /* a&k• control char into alphabet ollar •/
if((atr[O] • cli I Ox7f) c • 'I
,. tU:rn
/* turn
/"* turn
/* turn
off-RTI, /OU'tl, /OVT2 .,
off ax interrupt• •/
off ITS, /OUT1, /OUT2 */
off RX interrupt• */
)
_aetvideoaode C_DUAVL!'llODB) ;
}
/*****************************
DD
******************************/
Oo
Rf}
~
~L
~
~~~
SEMICONDUCTOR LIST 1995
TO PLACE YOUR ORDER
FOR A FREE COPY
Monitoring a typical data link using the protocol analyser. The PC on the right is
running the analyser software, with the adaptor cable patched into the link
between the centre computer and the modem on the left.
priority interrupt has occurred to delay
it briefly. The interrupt handling sequence for both SIO ports is:
A. read the data from the interrupting
SIO port
B. clear the upper bit for COMI or set
the upper bit for COM2
C. save it in the buffer
D. increment the buffer pointer
E. reset the SIO interrupts
F. reset the interrupt controller
G. return to the point of interrupt in
the foreground program.
The main loop, or foreground program, displays the data from the buffer.
If the two buffer pointers are equal,
then there is no new data so no action
is taken by the foreground program. If
they are not equal, there must be some
data to display and the main loop gets
it, checks the upper bit to determine
direction and therefore background
colour, checks it to see if it is a
control character and displays it with a
preceding 'A' if it is; otherwise it just
displays it. The main loop also checks
the keyboard for function key [FIO]
keystrikes. If an [F 10] keystrike is
detected, the program restores the SIO
chips to the inert state, saves the circular buffer to a file (not shown in the
listing), and exits.
The use of colour backgrounds for
indicating direction makes it necessary
to use graphics mode and consequently
the Quick C outtext() function instead
of the usual printf() function.
The circular buffer may not look like
EDllOR'S NOTE
Mr Maull~ has vel)I kindly, provided
us with cof)ies,m both d1e.so1:1rce a~~- '
ecutable Al~, fo~ both . the proti:>tol
analyser {P)l~TAN}.p"°*lfiim ~ a matcfl, •
ing program to te'f'iew saved Ales <PROTOISl;>l, for i:U$t(ibuti<m to anyone Wishing •··
to buHd .hi$ anatvser. lilten!sted readers
can obtain cOl)ies ef·••flles by.~
us a forrnalled hip .d..., •flOppY 1fisk :·
(5 .25"/l .2MB or 3.5"/1.4M8J,: pl~ iii ~ . .
que for $tU:l(> t0·cover toPVing .and:retum ·•·.
postage wit!iin Australia.
...
one at first sight, because there is no
check to see when the top is reached.
In this case no top of buffer check is
necessary because the CPU is operating
in real mode and the segment register
setting of 8000 hex remains unchanged
while the offset increments from 0000
to FFFF hex and back to zero again
automatically. The effect of this is that
the buffer is circular, with an absolute
RAM address range from 80000 to
8FFFF hex, with an automatic end-toend wrap around.
The way the circular buffer pointers
have been used will cause run-time errors unless you tum the check pointer
function off, using the pragma shown
near the top of the listing.
Using this kind of buffer is not a
good programming practice, but it is
fast. A limitation of Quick C is that
only data rates up to 9600 bits per
second are provided. This is not a
hardware limitation, so that if you want
higher speeds you have to avoid using
the
bios serialcom() function in
Quick-C and resort to directly programming the SIO chips, in accordance with
the chip's data sheets.
C1>
PHONE: 02 796 2888
FAX: 02 796 3802
d
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OR WRITE TO:
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DELTA COMPONENTS
182 COOPER RD YAGOONA, NSW 2199
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•H!NIQ~
Up-to-date Information for
Design &. Repair
;ift~;
f•l#ft.I BOOKS&. CD-ROM
Q Integrated Clrcuts I Semiconductors
Q Parametric Access Library on CD-ROM
it> IHS CD-ROM
IC/Discrete Parameter Database
CD-ROM contains over 1,500,000 devices and
their parameters, Australian distributors, device
pinout information and many more features.
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FREE-CALL 1 800 062 299
FREE-FAX 1 800 817 716
.. .for a FREE catalogue & price list.
IHS AUSTRALIA Ply Limited ACN 059 947 410
Trading as: Hinton lnlonnalion Services
Locked Bag 7, Eastwood NSW 2122
Using the analyser
When the hardware is installed as
shown in the diagram the protocol
analyser can be run from the command
line: PROTAN <baud rate>
where baud_rate is any data rate supported by the hardware and software.
The minimised listing shows just two
of these as examples (i.e., 1200 and
9600), but you can add others to the
source code as required.
I have chosen arbitrarily to use the
function key [FIO] to exit the program. Any other key or keys can be
used provided the software is altered
to support it.
The listing shown omits the file handling needed to save and examine the
data later. This has been done to reduce
the printing space and to concentrate on
the real task. •>
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IWANTED I
SURPLUS ELECTRONIC
COMPONENTS
ROCOM IS WILLING TO PURCHASE
YOUR EXCESS/OBSOLETE STOCK.
CONSISTING OF: SEMICONDUCTORS,
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ROCOM ELECTRONIC COMPONENTS
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261 Hwitingdale Road HUNT!NGDALE VIC 3166
PO.BOX 142HUNTINGDALEVIC3166
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PH. 61 J 548 9229 FAX. 61 J 562 8772
MOBILE. 018564 085
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·.~· chronoro{iie!if ~utlt of'.Marconi's life ~nd actii~vemeot$ is
· lfi~rlWlned with a sepatat~ b~t tin~ti '~~~tiv~ of ~•r's own
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l'~ht vi~dt& to kW site$, such . as the Villa Gritone. near.
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' Fot tf\e fl'lOte UiChnicat r~a!fe~ ~her~s. al'° a 'seccifl,d half' ·"Pf the
. book
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:qi\'itJg an expanded f;fescription of mtmy items of
M~rconl~t equipment and construction details for making replicas.
It· au makes much more interesting ·reading than mo$t other
books dealing with this kind of subject.
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$4.95
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If paying by credit card phone Toll Free 008 800 933. Sydney
residents phone (02) 353 9992. Or mail your order (cheque,
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Company, Mail Order Department, Free Post No. 3, PO Box 199,
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If you do not want to cut up your magazine, photocopy or handwrite your details on a separate piece of paper.
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GOOD PLANETis
an environmental
magazine unlike
any other. Offbea~ quirky, angry, articulate, bright,
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and full of useful tips - CODD PLANET
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CODD PLANET covers diverse topics
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If you want to be informed and
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To subscribe to GOOD PLANET by credit card phone TOLL FREE 008 800 933
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and send with your payment of $17.80 for 4issues (cheque, credH: card details or
money order) to: Federal Publishing, Subscriptions Deparbnent, Free post No. 3,
PO Box 199, Alexandria NSW 2015 (no stamp required) or fax (02) 353 0967
NEW PRODUCTS
Fibre optic modem
Optical
Systems
Design has released its
OSD 157 fibre optic
modem. The unit was
originally designed for
tactical deployment
military applications,
where the emphasis is on
extreme ruggedness and
extremely low electromagnetic emissions,
necessary for a high degree of security. As a
result it is built into a
machined enclosure and
incorporates extensively
filtered power and data
lines.
The modem is a small
self contained unit which
can provide full duplex
synchronous or asynchronous communications over a two-fibre optical cable. It can be supplied either as
an eight line RS232/MIL-STD-188 modem or as a six line
RS422 modem. The eight line unit is internally selectable for
either RS232 or MIL-STD 188.
The modem operates with all commonly available multimode
fibres over at least 3km and can be optioned to operate over at
least lOkm of single-mode fibre. While normally used as a
modem, the OSD157 can also be used as a six or eight channel
multiplexer. The unit can be supplied either as a stand-alone or
for mounting in the OSD380 2RU (88mm) high 19" rack
mounting chassis which supports up to 14 such modems.
For further information circle 242 on the reader service
coupon or contact Optical Systems Design, 2/5 Yuko Place,
Warriewood 2102; phone (02) 913 8540.
Handheld scope/multimeter
The TekMeter 565 combines a true RMS multimeter and
an auto ranging digital storage scope (DSO) in the one compact handheld package. It has been expressly designed
for use by field technicians in the areas of installation,
repair and maintenance.
The instrument features a large easy to read LCD display,
which provides in addition to the normal analog and digital
measurements, simultaneous readout of max, min, max minus
min, hold and delta hold. In the scope mode the meter is an
autoranging two channel DSO with a bandwidth of 5MHz and a
sampling rate of 25MS/s. On-board cursors allow the measurement of delta volts, delta time and inverse delta time.
The multimeter section of the instrument has a 3-3/4
display (4000 counts) and measures DC voltage in the
range 400mV to 850V with a best resolution of lmV and a
stated accuracy of 0.5% + 5 counts. In the AC voltage range
the unit can measure the true RMS values of voltages be116
ELECTRONICS Australia, February 1995
tween 400m V and 650V in the frequency range l Hz to 5kHz.
Resistance can be measured up to 40M ohms with a resolution
of 0.1 ohms. The meter also features an audible continuity
test facility.
RF signal generator
The new SMY RF signal generators from Rohde & Schwarz
are designed for testing AM, FM and QM receivers. They can
also be used for component measurements. The generators
come in two models covering the frequency range from 9kHz to
1040MHz, or from 9kHz to 2080MHz. The generators are
claimed to be versatile yet cost effective, making them suited
for universal use in a laboratory, or in production and servicing environments.
The level range of the generators is from-140dBm to 13dBm,
which is sufficient even for high-sensitivity receivers. High
level accuracy and low RF leakage allow accurate and undegraded sensitivity measurements. The high accuracy of the
carrier frequency allows reliable testing of pagers and receivers
with digital squelch.
Because the instruments have a lHz frequency resolution,
they are also suitable for measurements on extremely narrowband devices. The integrated AF synthesiser output is from lHz
to 500kHz which can also be used as an AF signal source for
external applications.
The generators can be integrated via an IEC 625,'IEEE 488
interface into an automatic test system.
For further information circle 241 on the reader service
coupon or contact Rohde & Schwarz, PO Box 6105, Silverwater 2128; phone (02) 748 0155.
The Tekmeter is available for hire from Tech-Rentals. For
further information circle 243 on the reader service coupon or
contact Tech-Rentals, PO Box 621, Ringwood 3134; phone (03)
879 2266.
GoldStar
Battery monitor is PC based
Anton Piller (Australia) has released a new product to make
battery monitoring simpler and less expensive. The system,
designed and manufactured in Australia, continually and accurately monitors battery voltages, temperatures, charge and
discharge currents of complete battery strings and/or individual cells.
The Battman battery management system incorporates
software which allows the operator to quickly identify defective
battery cells with a glance at the computer monitor.
Graphical displays and coloured bar charts highlight the condition and performance of the batteries and this information is
continually recorded so that the history can be retrieved, printed
and assessed at any later time. The most significant benefit of
the system is the ease of identifying when a fault occurs, or
more importantly before a fault develops.
For further information circle 244 on the reader service
coupon or contact Anton Piller (Australia), 4 Expo Court, Mt
Waverley 3149; phone (03) 562 8466.
Parallel interface tester
The new PIT system is a professional handheld Centronics
parallel interface tester, designed to help solve problems between a computer and its printer. Powered either from a DC
plug pack or run on internal batteries, the PIT system is available in two models, the PIT 100 and the PIT 200.
Both models feature ASCII 'fax' testing and can measure and
New Electrostatic Sate Soldering Station
THE VERSATILE SA-562E·A
DESIGN FEATURES
• LED heater indication
•Variable temperature control knob
• External calibration ports
• Slim-profile iron handle with
silicone rubber grip • Flexible,
non-burn silicone iron cord
sleeve • Externally fused
• Aust. Energy Authority
Approval No. N-1/933
• Closed loop
temperature control
•315°C to 425°C
SPECIFICATIONS- SA-562E-A:
• Input: 230V AC, 50160 Hz • Iron: 70W, 230V
•Heater: Ceramic with Embedded RTD •Cord: 3-Wire, Australian Plug
•Dimensions: 117.Smm x 115mm x 133mm •Shipping Weight: 1.1 kg
•
ELECTRONIC DEVELOPMENT SALES m LIMITED
A.C.N. 001 363 480
Unit 2A, 11-13 Orion Road, (P.O Box 822), Lane Cove NSW 2066
Phone (02) 418-6999 Fax (02) 418-6550
o• 882
READER INFO NO. 22
• DC to 20MHz Dual Trace
• Extensive use of surface mount
technology for high performance
• 1mV/div maximum sensitivity
• 150mm rectangular CRT with internal
graticule
• TV sync separator circuitry for stable
TV observations
• Includes x1/x10 probes worth $64
Brief Spec CRT150mm/1.9kV/P31 • Verlica/dc to 20MHz (-3dB), 5mV to 5V/div
in 10 steps (plus x5 mag) :±3% accuracy, 17.5ns risetime • Horizonta/0.2µs to
0.2s/div in 19 steps, x1 Osweep mag • Trigger auto, norm, TV-V, TV-H • X-Yphase
diff <3° • Z mod 5Vp-p, 2MHz • Mechanica/320x140x430mm, 7.5kg
OS9020P
$650
ex tax
Ask about GoldStar 40 and 60MHz scopes
Also check out the Goldstar range of
Digital Storage Oscilloscopes
Feature
083020
083040
083060
Real Time Bandwidth
Sampling Rate
Input Channels
Record Length/Channel
Save Rel. Memory
Cursor Readout
B Sweep Function
RS-232C Interface
Price (ex tax)
20MHz
20Ms/s
2
2k
Yes
Yes
Yes
Yes
$1910
40MHz
20MS/s
2
2k
. Yes
Yes
Yes
Yes
$2450
60MHz
20MS/s
2
2k
Yes
Yes
Yes
Yes
$2995
Available from leading electronics distributors
(I)
including • Prime Electronics (02) 746 1211 • Dixontech (049) 69 5177 z
• G.H.E. (002) 34 2233 •Trio Electrix (08) 234 0504
~
• St Lucia Electronics (07) 252 7466
~
a:
d
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li.IN•~~~ES ~
VIC (03) 419 9999 • NSW (02) 736 2888 •OLD (07) 252 5231
SA (08) 243 2555 •WA (09) 443 1522 All prices ex tax
NEW PRODUCTS
display data rates along the interface. Both units also feature
display LEDs to show input and output status signals, and have
built in test functions accessible with a push of a button. The
PIT 200 has a step function to monitor the transmission of individual characters. The PIT 200 can completely test parallel
port operation as well, and there's a facility to store user test
files for graphics printers and plotters. The PIT 100 is priced at
$150 and the PIT 200 costs $200.
For further information circle 246 on the reader service
coupon or contact TCG Manufacturing, 53 Balfour Street,
Chippendale 2008; phone (02) 698 5000.
The switch contacts are designed for momentary actuation
and can handle 0.2W at 24V DC. Switching current is a maximum of 50mA DC and operating life at maximum switching
power is greater than 500,000 cycles. Contact bounce time is
less than 3ms. Operating force required to actuate the switch
is between 0.48 and 0.72 newtons with a travel of 0.35mm.
The switch can be safely reflow soldered via its gullwing style
contacts. Physical size is approximately 6mm square with a
height of l.5mm. Packaging is 16mm wide continuous tape
Compact phone plug
Planned Products has introduced two new greases developed
for applications requiring electrical .conductivity, lubrication
and protection. Available in silver and carbon forlnulations, the
new Circuit Works conductive greases protect assemblies from
wear and environmental hazards, while providing excellent
electrical and thermal conductivity.
When used at low to medium loads and speeds, the
greases lubricate and protect assemblies, while forming conductive pathways, contacts, connections, static drains and
grounding. Based on advanced silicone lubricants, the new
greases are chemically inert, thermally stable and nonflammable. Assemblies are protected from moisture, oxidation,
radiation, corrosion, and corrosive atmospheres with a single
grease application.
The 7100 Circuit Works Silver Conductive Grease is formulated for maximum electrical and thermal conductivity
with typical resistivity of <0.01 ohm/cm. The silver grease is
thermally stable from -57° to 252°C and features a dropping
point of 255°C. The 7100 Silver Grease exhibits excellent
thermal conductivity of 50 (BTU/Hr/Sq.Ft/in/F0 ) while
maintaining a flash point of <520°C. Unworked and worked
penetration are 210 and 250 respectively, with steel on steel
wear measured at 1.5mm.
The 7200 Carbon Conductive Grease has typical resisitivity
of <30.0 ohm/cm. The carbon grease provides effective lubrication from -57 to 252°C. No dropping point was observed at the
520°C test limit. The 7200 Grease maintains a flash point of
<520°C. Unworked and worked penetration are 335 and 338
respectively, with steel on steel wear measured at 2.0mm. New
Circuit Works Conductive Greases are available in a variety of
packaging options including plastic syringes and bulk jars.
For further information contact Planned Products, 303
Potrero Street, Suite 53, Santa Cruz, CA 95060-2760, USA;
phone (408) 459 8088, or fax (408) 459 0426.
The Neutrik NP2RCS is claimed to be the world's smallest
right angle mono phone plug. Measuring 65mm in length with a
16mm body diameter, the plug uses Neutrik's chuck-type cable
strain relief and features a robust metal connector body and
nickel plated connector surfaces. The connector can be assembled quickly and easily and provides ground termination
without soldering.
For further information circle 248 on the reader service
coupon or contact Amber Technology, 5 Skyline Place, Frenchs
Forest 2086; phone (02) 975 1211.
Side actuated SMT switch
Alcatel Components has released a new surface mount switch
that features actuation in a plane parallel to the PC board surface. Designated the KSM, the new switch is a low profile
tact switch that is single pole with normally closed contacts.
JJ
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118
ELECTRONICS Australia, February 1995
Conductive silver and carbon greases
reels with 2000 switches per reel and the product can be picked
and placed by all standard production equipment.
The KSM is ideal for applications such as 'push to talk'
switches, position sensing switch, card edge reset switches and
other soft tactile card edge applications.
For further information circle 247 on the reader service
coupon or contact Alcatel Components, 248 Wickham Road,
Moorabbin 3189; phone (03) 444 1566.
Tough 100 Series
• 3 3/4 digit 4000 count display
• 42 segment analog bargraph
•Freq., caps, adapters etc
• Min/Max hold
• Data hold and Relative
• Auto power off
Logic analyser is 'like a scope'
Hewlett-Packard's new HP 54620A Logic Analyser is the
latest addition to the firm's range of 'affordable' test and
measuring instruments, and unlike many logic analysers is desgined to ffer the same ease of setup and use embodied in the
popular HP 54600 series of digital scopes.
The HP 54620A provides 16 logic analysis channels, with the
ability to trigger on edges, patterns, duration times and sequences. It samples at 500MS/s, to ensure the capture of narrow
glitches, and provides a bright, crisp screen display updated 15
times per second regardless of the number of active channels.
As with the 54600 DSO's the analyser also provides automatic
measurement of frequency, period, duty cycle, width, delay and
hold time.
A handy feature of the HP 54620A is the same kind of
'Autoscale' button provided on the 54600 scopes, allowing very
rapid and convenient setup. The analyser provides a trigger output which can be used to trigger a scope, and is also compatible
with the HP 54650A and HP54651A interface modules - and
the HP34810A BenchLink/Scope software - used by the
54600 series scopes.
The Australian price of the HP 54620A Logic Analyser is
$4498 plus tax. Further information is available by calling HP's
Customer Service Centre on 13 1347.
Performance
101
103
DC Voltage
0.7%+2 0.6%+2
AC Voltage
1%+5 0.8%+5
DC Current
0.8%+2 0.7%+2
AC Current
1.5%+5 1.3%+5
Yes
UL 1244
Price (ex tax)
$185
$225
Improved 90 Series
•
•
•
•
•
2000, 3200 & 4000 count
True rms models
Beep-Guard"' on amp ranges
Multi functions
Water resistant
Features
Count
Bargraph
Freq/Transistor
Data/Peak Hold
Delay hold
BeepGuard
Price (ex tax)
Midrange gang programmer
Data 1/0 has introduced the PSX400, a new multiple purpose
gang or set programmer for low to medium volume prototyping and manufacturing applications.
Memory and rnicrocontrollers can both be programmed on
the PSX400. Four and eight socket modules are available for
32-pin and 48-pin DIP, and other packages such as PLLC,
SOIC, and TSOP are supported. TaskLink allows users to set up
standard 'programming' tasks that include all the steps required
to process a certain set of devices or functions. The PSX400 is
designed to download serially at up to 38.4kbs, but can be enhanced with an optional IEEE-488 port to achieve transfer
speeds of up to 170kB per second.
For further information circle 245 on the reader service
coupon or contact Nilsen Technologies, PO Box 930, Collingwood 3066; phone (03) 419 9999. •:•
105RMS
0.3%+2
0.5%+5
0.4%+2
1.0%+5
Yes
$299
Bench 203
• 4000 count + 42seg bargraph
• Frequency, capacitance etc
• AC/DC operation
$393
Pocket.Size 63
•
•
•
•
•
31/2dig, 2000 count
&DOV protection
0.8% accuracy
Versatile holster
Hold function
93E
2000
95
4000
Yes
p
Yes
p
Yes
$139
$139
97RMS
3200
65 seg
D
Yes
Yes
$175
51 Thennometer
• KType T'cple
e 1°to.1° resolution
• 0.3% accuracy
•Max record
• Hold function
$130
32 Current Clamp
•&ODA ac/dc
•Hall EHect
• 2.0% accuracy
• 34s or 20X4Dmm
e Use with DMM
$120
$87
Available from leading electronics distributors
including• Prime Electronics (02) 746 1211 • Dixontech (049) 69 5177
• G.H.E. (002) 34 2233 •Trio Electrix (08) 234 0504
• St Lucia Electronics (07) 252 7466
IVJN·~~~e~~
VIC (03) 419 9999 • NSW (02) 736 2888 • QLD (07) 252 5231
SA (08) 243 2555 •WA (09) 443 1522
All prices ex tax
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Solid State Update
KEEPING YOU INFORMED ON THE LATEST DEVELOPMENTS IN SEMICONDUCTOR TECHNOLOGY
0
Transparent SIP
photodiode/amplifier
Burr-Brown's new OPT202 is packaged in a new 5-pin SIP
that allows light to originate from the 'side' of system boards
rather than from perpendicular sources. The device combines a
large 2.3 x 2.3mm photodiode, precision FET input trans-irnpedance amplifier and IM feedback resistor on a single chip to
provide high performance at a low cost.
The IC is suitable for many industrial applications including
medical and laboratory instrumentation, position and proximity
sensors, photographic analysers, machine tool controllers, and
smoke detectors. Its innovative combination of photodiode and
amplifier eliminate many problems associated with discrete
design, such as leakage current errors, noise pick up, and gain
peaking due to stray capacitance. Photodiode responsivity is
0.45A/W at 650nm.
Key specifications include: IM feedback resistor, 2mV dark
errors, 0.45A/W 650nm) responsivity, 400uA quiescent current,
0.05% nonlinearity, and +/-2.25 to +/-18V supply range.
For further information circle 280 on the reader service
coupon or contact Kenelec, 2 Apollo Court, Blackburn 3130;
phone (03) 878 0824.
Surface mount
voltage regulators
Featuring full thermal shutdown and
current overload protection, the new
ZMR250 and ZMR500 fixed voltage
regulators from Zetex deliver 2.5V and
5V respectively. Both devices are available in 2.8 by 1.3mm SOT23 surface
mount packaging.
In standby mode, the new regulators
take only 25uA and 50uA respectively,
which is a reduction in power consumption of up to 100 times relative to the
standard 78L series. As well, the devices
are unconditionally stable and don't need
external capacitors.
Output current capability of both versions is 50mA, and power dissipation is
500mW for the SOT23 package or
DC to DC
converters
A new series of ultra miniature 0.9W,
single and dual output DC to DC converters have been announced by Cygnus Technology from Japan. The
devices are available in 21 different
configurations.
The inputs and outputs are isolated,
they feature excellent regulation, thermal
load protection circuitry and on-board
short-circuit protection.
Their metal case reduces noise radiation and guarantees high reliability
against vibration, moisture and heat.
Other features include: 16 pin DIL
compatible package, 12 x 20 x lOmm
size, high efficiency, low noise and
bum-in and testing during manufacture. The input voltage range is 5, 12
and 24V DC, giving single outputs
120
ELECTRONICS Australia, February 1995
600mW for the T092. Line regulation
for the ZMR250 is 1OmV (worst case)
for all input voltages from 4.5V to the
maximum input rating of 20V. Regulation of the ZMR500 is also lOmV maximum for inputs down to 7V.
Applications include mobile telephones, cameras, laptop PCs, camcorders and pagers. Over their operating
temperature range of -55° to 125°C, the
regulators have an average temperature
coefficient of typically O. lmVfC, when
delivering an output current of 5mA.
Output tolerances are 2.438 to 2.563V
for the ZMR250 and 4.875 to 5.125V for
theZMR500.
For further information circle 273 on
the reader service coupon or contact
GEC Electronics Division, 38 South
Street, Rydalmere 2115; phone (02)
638 1888.
Microstrip amplifiers
from 0.1 - 20GHz
ranging from +5 to + 15V and dual outputs from +/-5V to+/-15VDC.
For further information contact Cygnus Technology, 4-30-15, Okusawa,
Setagaya, Tokyo, Japan.
MITEQ's NSH series are among the
smallest discrete multistage amplifiers
available. Features include AFS amplifier performance, gold plated chassis and gold filled VIGS for enhanced
grounding. The amplifiers are suitable
as cascadable building blocks and can
be placed between the cavity of a 25m1
Electrometer-grade op-amp
Burr-Brown's new OPA129 is an electrometer-grade operational amplifier in 8-pin DIP and S0-8 surface mount packages. Its lOOfA (max) input bias current makes it ideal for use
with high impedance sensors, low drift integrators, pH probe
amplifiers, and ion gauge measurement.
The device features dielectrically-isolated FET fabrication,
which reduces input bias current by a factor of 10 to 100 and
eliminates isolation-junction leakage current without the need
for small geometry FETs. The pinout allows rooms for circuit
board guard traces - even with the tiny S0-8 package.
Key specifications include an ultra low bias current of
lOOfA, an offset voltage of 2mV, drift of lOuV!°C, and a noise
figure of 15mV/"Hz at lOkHz.
For further information circle 275 on the reader service
coupon or contact Kenelec, 2 Apollo Court, Blackbum 3130;
phone (03) 878 0824.
substrate. They are supplied for easy
soldering or with a screw mounted chassis. Custom frequency, gain and noise
figure options are also available, and a
three year warranty is also offered.
For further information circle 272
on the reader service coupon or contact Electronic Development Sales, PO
Box 822, Lane Cove 2066; phone (02)
418 6999.
Ultra-low dropout
regulator transistor
Zetex has launched a PNP power
regulator resistor claimed to feature an
unrivalled saturation-versus-gain performance in its class. This is important for
manufacturers of portable equipment as
it can extend battery life.
In high current equipment the need for
power regulation with low dropout, high
efficiency and low EMI, tends to
prohibit the use of many monolithic
devices. This has resulted in the development of monolithic controllers that use
an efficient PNP series pass transistor.
Developed for this purpose, the ZBD949
features a high gain across a wide
operating current range and a very low
collector to emitter saturation voltage.
The T0126 packaged power regulator
transistor has a typical collector-emitter
saturation figure of 80mV at lA, rising
to 360mA to SA. Gain of the transistor is
typically 200 at IA and 140 at SA. At the
device's peak current handling capability
of 20A, DC gain is still 35. Maximum
collector-emitter voltage of the ZBD949
is 30V, and its collector-base rating is
SOY. Properly heatsinked, the device
can dissipate 25W. It can dissipate
2W without any heatsinking. Capable
of operating over a temperature range of
-55 to 200°C, the ZBD949 is suitable for
a wide range of applications, including
automotive under-bonnet circuitry.
For further information circle 278 on
the reader service coupon or contact
GEC Electronics Division, 38 South
Street, Rydalmere 2116; phone (02)
638 1888.
Trident licenses
C-Cube's MPEG-1
Trident Microsystems, a supplier of
graphics and multimedia ICs for the PC
market, has licensed C-Cube's CL450
MPEG-1 video decoder technology.
The integration of video and graphics
technologies will reduce system costs
while increasing functionality and performance as multimedia systems
move into the mainstream PC market.
This integration will bring the cost of
building MPEG-1 playback boards
below the $80 mark, and make the addition of multimedia video capabilities
to graphics boards or mother boards
very inexpensive.
Under the terms of the agreement, Trident has the right to use C-Cube's
CL450 circuitry for integration into its
video and graphics controllers and also
establishes a relationship between the
two companies for further cooperation
on future products. C-Cube, in tum, will
have the opportunity to sell some of
these integrated products.
For further information circle 271 on
the reader service coupon, or contact
Veltek, 18 Harker Street, Burwood 3125;
phone (03) 808 7511.
Semi-custom linear ICs
The ZLA700 from Zetex is a semicustom linear IC that features a flexible
linear array process. Involving a series of
eight standard bipolar arrays with between 33 and 630 transistors, the process
cuts both end product and design costs.
End product costs are reduced since the
arrays allow high component use.
Design costs are reduced as the user carries out the chip design on a PC, via low
cost, easy to use software.
Besides providing accurate emulation
and modelling routes, Zetex advocates
the building of a prototype. To this end,
discrete components accurately matching their array based counterparts are
available, providing a high degree of
confidence in the success of the design.
Since only one level of the IC manufacture is customised, development and
production time scales are substantially
reduced. Additional benefits are reliable
end products with no restriction on minimum order quantity, and extremely low
NRE charges, bringing semicustom
linear ICs within the reach of many
small to medium sized companies.
For further information circle 276
on the reader service coupon or contac
GEC Electronics Division, 38 South
Street, Rydalmere 2116; phone (02) 638
1888. ·>
----------------~
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all semicon's considered
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Voice: (61 2) 452 6100 a:
Fax: (612)452 6102
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Silicon Valley
NEWSLETTER
Multimedia rules
at Comdex 94
190,000 people, 2200 exhibitors,
7000+ new products and 2.5 million
square feet of booth space made the Las
Vegas Comdex 94, another in an unbroken string of 16 ever-bigger shows.
And there appears no end in sight, as
close to half a million people are expected to visit the annual event by the
end of the decade.
One of the reasons for the continued
explosive growth of the PC market is the
strong emergence of the home computing
market. Already accounting for 40% of
the PC market in the United States, the
consumer PC segment will increase to
50% this year. And between 25 and 40%
of customers in the retail area are first
time PC buyers, according to reports out
of the retail industry.
More so, of all the PCs now in use in
business and the home, more than half
are out dated in terms of enabling their
owners to enjoy the benefits of the
multimedia revolution. And what's
more important, the rapidly falling
cost of computing is allowing users
to upgrade to higher levels of machines
at a much faster pace than in the past.
In the US consumer PC market CDROM capability is virtually a must,
with 70% of systems sold featuring
built-in CD-ROM.
Unlike the previous Comdex, which
was dominated by the first PDAs, Pentium and PowerPC machines, and wireless computing products, Comdex 94 had
few if any breakthrough, show stopping
products that have the potential of
moving the industry in new directions with the exception of Windows 95 and
Microsoft's Marvel on-line network.
Ironically, neither of the two products officially exist, and probably won't be
available for another six months. But you
would never have guessed that, as it was
hard to find any booth that wasn't touting
some support for Windows 95. Many
firms demonstrated prototypes of Windows 95 versions of their software.
IBM made a big splash with its
recently released WARP version of
OS/2, encouraging visitors to 'GET
WARPED'. But the mood at Comdex
was clearly tilted towards Windows 95,
on which most software companies are
betting their resources. Most analysts
and industry executives at the show
predicted the program will take the industry by storm, easily exceeding the
phenomenal sales of Windows 3.1 just
three years ago.
In contrast to the general excitement
over Windows 95, there was virtually no
attention paid at the show to the announcement made just days before the
show by Apple, IBM, and Motorola that
they had agreed on a new PC hardware
platform. Few seemed to care.
At his news conference, Microsoft's
Bill Gates reserved his harshest words
not for federal investigators examining
Microsoft's competitive practices but for
the IBM/Apple/Motorola alliance to
produce a new personal computer clone.
Gates insisted he couldn't understand
why anyone would consider the alliance
a big deal. "They basically announced
they finally figured out how to have a
common BIOS," Gates said, referring to
the software on a chip that serves as a
sort of glue between microprocessor and
operating system. "I'm still wondering
what took so long."
Multimedia big time
PCs with built in telephone communications and video teleconferencing
capabilities look like becoming common in the next two years. Integrated
technology displayed its CompuPhone 2000, which features a modified 101
key PC keyboard and built-in headset.
122
ELECTRONICS Australia, February 1995
Among industry trends it was impossible to ignore the explosive proliferation
of multimedia, which has been building
up for the last three years - culminating in a near take over of the show.
Whereas in 1993 the multimedia exhibit was contained in the smallest of
Comdex's seven exhibit halls, this time
the entire massive Sands Convention
Center had been taken over by the multimedia industry - accounting for more
than 1300 booths at the Sands alone,
with hundreds more companies exhibiting some form of multimedia products in
other areas of the show.
Long lines formed at booths featuring
glitzy state of the art multimedia productions. At least two companies, Virtual 1/0
and VictorMaxx, introduced consumer
level 'virtual reality' headsets.
Virtual 1/0 of Seattle and VictorMaxx
Technologies of Deerfield, Illinois said
they are ready today to satisfy consumer
demand for consumer virtual reality head
gear, a market that is expected to quickly
become a billion dollar industry over the
next couple of years.
VictorMaxx showed its new CyberMaxx visor (US$700), which provides
a completely emersive stereographic
environment in which to play computer
and video games. The headset, which
weighs just over 13 ounces provides a
63 degree viewing angle. By turning
your head, players can get a 360 degree
view of their surroundings. And they
will see a virtual sky or ceiling when
looking up and the appropriate floor
type (street pavement, carpet, etc.,) when
looking down.
The CyberMaxx is aimed specifically
at PCs and video games. VictorMaxx
said the company is currently working
with independent game developers to
produce virtual reality games that take
advantage of its headset.
Meanwhile, Virtual 1/0 had long
lines waiting at the theatre in its booth,
where the company was using action
filled video to demonstrate its versatile
virtual reality visor which can be used
to display images from a range of input
sources, including PCs, television,
VCR or laserdisk.
The basic unit costs just US$399. A
$700 version adds a 'headtracker' which,
just like the CyberMaxx, allows for true
virtual reality games by using head
movement to control what is seen on the
screen in front of the player.
Unlike the CyberMaxx, the 'Personal
Display System' from Virtual 1/0 allows
users to retain peripheral vision of their
surroundings, making the device useful
in industrial and medical applications.
The maximum viewing angle is limited
to 180 degrees.
Finally, while the Virtual 1/0 devices
use two small projection TVs, the CyberMaxx uses two colour active matrix
LCDs which provide a sharper image.
Both systems feature high powered
stereo headsets.
Ann-Marie Larkin, who is vice~presi­
dent at Motorola's RISC Microprocessor
Division, said that already more than 300
PowerPC applications are out on the
market with dozens being added each
month. Larkin said the alliance has
recently introduced development tools
that simplify the process of porting applications to the PowerPC platform.
Sti'u, beyond the Apple Macintosh,
there is no computer maker that yet sells
a significant number of PowerPC based
machines. Many had hoped IBM would
have been able to get its PowerPC based
desktop system on the market by Comdex, but IBM has postponed the launch
until after development of the OS/2
based operating system is completed.
As far as Apple is concerned, the
company launched two new PowerMac s. The PowerMac 6100 is a
machine that sports both a PowerPC
601 and Intel 486-DX/2-66 processor,
allowing the computer to run Macintosh, Windows, DOS and native
PowerPC applications all at the same
time. In fact, users can transfer data between applications from the different
operating systems with simple pointand-click 'cut and paste' moves. The
system also supports two monitors,
without the need to add an additional
video card.
Meanwhile, the PowerMac 8100/11
features the llOMHz version of the 601
PowerPC chip. This machine is aimed at
multimedia users; it has l 6MB of RAM
and a 2-gigabyte hard disk and can run
Windows and DOS applications.
IBM Workgroup
. In an effort to show its determination
to leave its proprietary past behind and
become a company committed to open,
flexible, and accommodating architectures, IBM used Comdex to launch 'IBM
WorkGroup', a broad range of Desktop
functions to automate much of the information flow that is critical to the success
of a group of people working together in
an organisation.
IBM WorkGroup is based on a number
of 'components' the company has
released separately during the past 18
months, while still more elements of the
WorkGroup are in development and will
be added later.
Some of the basic functions available
today include fax, directories, scheduling, calendars, chalkboards, work
management, messaging, multimedia
libraries, search technology, personal
video-conferencing, and decision support. Speech recognition is high on
IBM's list of priorities to add to the environment.
In a key feature, IBM has built in intelligent data 'agents' which automatically
perform tasks for their user.
"This is a new concept", explained
Ralph Pollock, program manager of
WorkGroup. "You have a research agent
working for you in the network that will
feed you data based on a set of rules, and
which can learn based on what you
select. Another agent, much like a
secretary, lets things happen on your behalf. A message from your boss marked
'Urgent' will automatically have you
paged or generate a fax to your hotel.
The action is taken on a pre-determined
combination of events and rules."
Pollack said WorkGroup can be
scaled for organisations as small as 10
people to international conglomerates
r::>
with 100,000 workers.
PowerPC puts
on big effort
The IBM/Apple/Motorola alliance
again put together a big effort in support
for the PowerPC. In a large tent outside
the main convention hall, some five
dozen companies were showing applications written for the PowerPC. Even
Microsoft was represented, showing. for
the first time, Excel and Work, SQL
Server, and SNA Server applications running native on the Windows NT operating system for the PowerPC.
The Virtual 110 stand featured a theatre, where the company was
demonstrating Its 'Virtual Reality' visor/headset, using action filled video
material.
ELECTRONICS Australia, February 1995
123
SILICON VALLEY
Gates and Grove
unveil their visions
Andy Grove and Bill Gates, whose
microprocessors and operating software
represent the heart and soul respectively,
of the massive personal computer industry, used their key note addresses at
Comdex to present their view of the near
time future of the PC revolution.
Microsoft chairman Bill Gates in particular, appeared to make a strong bid to
become the industry's premier visionary,
a position left vacant ever since John
Sculley was removed at Apple 18
months ago.
Gates presented his vision for the year
2005, a point in time when Gates
foresees computers to have become all
pervasive in just about every facet of life.
They come in many ·shapes and forms,
and are capable of presenting the user
with vast resources at their fingertips or, as in Gates' vision, at their lips since
most devices in the future will operate
mostly on voice recognition. "I think
voice recognition will become a really
central way to advance the computer.
We'll see speech command capabilities
as well as the ability to store speech and
play it back. You can see the words displayed as the person speaks.,,.
Gates spoke before a capacity crowd
of more than 7000 people, and used a
motion picture quality video to illustrate
different parts of his vision. The story in
the ·video revolved around two detectives
solving the murder of an art smuggler,
and a high school student creating a multimedia report for a homework assignment. Along the way, the video showed
how personal computers will show up as
'electronic wallets', on wall displays in
the kitchen, on our living room walls for
art display, on dashboards in our
automobiles, in class rooms, and even in
pay telephones.
By 2005, Gates said "these devices
will be pervasive. Everybody will be
using them, and the critical mass of information will be there," adding that the
basic technology to realise Gates' vision
"already exists today in some form and
is simply waiting to be improved and put
into place."
Not surprisingly, in Gates' vision, computing in 2005 is standardised on the
Windows user interface. Gates made no
secret of his plans for Microsoft in the
future market place by creating the
standards for information to be packaged,
and sent among computers. "You need to
have a common architecture," he said.
124
ELECTRONICS Australia, February 1995
In Gates' information society, wallet
size computers will replace pay phones
and automatic teller machines. They will
allow people to pay with 'virtual cash' by
punching a few buttons to 'shuffle'
electronic money from their wallet into
the electronic register of a retailer. They
will also replace credit cards, cellular
phones, pagers, metal car and house
keys, and paper photos of the kids.
Observers pointed out several seemingly disturbing facets of Gates' view,
particularly the wealth of information instantly available on individuals and businesses with only a phone number as the
password. Information ranging from
financial transactions to detailed medical
records, to criminal records.
Gates said some of these issues,
notably privacy and access for the
poor, would have to be dealt with by
politicians as much as by technologists.
"You need to use both technology and
policy to make sure people are confident enough to use the information superhighway for all their activities," he
said of privacy.
And, he said, computer makers also
must make all the information this future
promises easy to use by individuals who
are often afraid of technology. "That's a
challenge to the industry," he said.
CPU based multimedia
Meanwhile, the man who will be
providing the building blocks for Gates'
Vision, Intel's Andy Grove, returned to
Comdex to update his company's future.
Grove's vision was only two to three
years out into the future, and focused on
the evolving PC platform. His presentation centred around the first public
demonstration of the concept of 'Native
Digital Processing' (NDP) in which the
PC's CPU, with the help of only
software, takes over virtually all multimedia functions, eliminating the need for
a multitude of video, audio, graphics and
other add-in cards.
In the demo, Grove linked himself up
with two Intel factories in Santa Clara
and Ireland, and showed a video conference call in which two managers at
each end discussed a manufacturing
problem, and shared key documents on
which each pencilled in remarks to illustrate arguments.
While Grove's vision would spell
doom for much of the multimedia add-in
board industry, Grove said it is imperative that the CPU takes command of
most multimedia and communications
functions ahead of the arrival of the information superhighways, which will add
a vast amount of multimedia demands on
the system - demands which cannot be
effectively and economically handled
with separate pieces of equipment.
Grove showed a slide of the back of a
common networked multimedia PC,
featuring no less than 16 connectors to
and from seven add-in cards and various
other devices, essential to enable today's
PC to perform multimedia operation.
The move towards all-software-based
Native processing will not only make
things simpler, it will allow the cost of
multimedia computing to come down
dramatically. With NDP every PC becomes a video teleconference capable
station, with the addition of just the
software and a video camera and
microphone.
Gates unveils 'Marvel'
During a press luncheon at Comdex
Bill Gates also demonstrated the on-line
network his company has been developing under the code name 'Marvel'.
When officially launched the service
will be known as 'The Microsoft
Network' and will be bundled with every
copy of Windows 95, a move that has
raised outcries of unfair competition
among existing on-line service providers.
Almost with a single click of the
mouse, millions of PC users will instantly become subscribers to the Microsoft
Network, which will be made available
in 35 countries and in 20 languages. The
network could have as many as 20 million users by the end of 1995 - 10 to 20
times the subscriber base of each of the
three largest existing services (CompuServe, America Online and Prodigy).
Gates, however, denied the Microsoft
service is anti-competitive, saying users
still must elect to subscribe. And he argued that competitors could reach agreements
with
other
computer
manufacturers. "The key question is
growth of the market. It's now a very
poor business," he said, referring to the
low percentage of computer users who
subscribe to on-line services. While 40%
of today's Windows users have modems,
only 10% subscribe to any on-line service. "That's a huge opportunity for content providers," Gates said.
The Microsoft Network will also be
dramatically different from existing online services in the way people will pay
for its use. Unlike current services which
charge users hourly and monthly fees,
Microsoft Network users will be charged
for what they purchase - whether it is a
newspaper article, stock quotes, a
sweater at an electronic boutique. The
Network, Gates said, "will act as a platform for independent content and service
providers, who will offer their own pricing options." •:•
Australia's Largest Range Of
Satellite Receiving Equipment
SPECIAL C BAND PACKAGE
PACE 199 CHANNEL 4dB LOW THRESHOLD DUAL INPUT RECEIVER
1.8 METRE C BAND KU BAND HIGH GAIN POLE MOUNT DISH
CHAPARRAL HIGH EFFICIENCY COMBINED LOW NOISE LNB FEED AND POLARIZER
$ 949. 00
Including sales tax
Australian Distributors for PACE satellite Receivers and Equipment
Enquire for our free comprehensive catalogue
t--
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(SkiDdia)
SKANDIA ELECTRONICS PTY LTD.
HEAD OFFICE: 183 BURWOOD RD., HAWTHORN, VIC, 3122.
TEL: (03) 819-2466 FAX: (03) 819-4281
NSW OFFICE: SUITE 12, 354-356 CHURCH ST., PARRAMATTA, NSW. 2150
TEL: (02) 630-0888 FAX: (02) 630-8690
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PC DIAGNOSTICS MADE EASY
SLASH DOWNTIME AND
OPERA TING PROBLEMS
PC WON'T BOOT? THEN JUST
KICKSTART ITI
With PC ProbeN you'll save time and money when your PC starts
Don't replace your motherboard, don't call service, use
acting up. In one easy-to·use package you get Diagnostics, V.us
Protection (for over 700+ known viruses), Benchmarks (Including the KlckStart 2™. When serious hardware problems occur,
• nothing gets you up 111d running as last. KickStart 2
famous LandMark System Speed Test"'), Performance Ennancement
UIHities, and System Information. Combined, this arsenal of tools will
measures power wit/in 2.5% on all four voltages, shows
keep your system up and running at peak performance and remove
Power-On Self· Test (POST) failure codes, and features on·
the mystery about what's inside.
board ROM.IJBSBd diagnostics allowing you to determine and
PC Probe diagnostic testing quickly isolates the source of hardware
f'Bmedy the problem cµiclcly, easily, and inBX/)BnSively!
problems, even IOcating bad RAM chips. tt tests system board, RAM,
video, keyboard, com ports, floppy and hard drives, Ethernet card and Built-in serial and parallel 1/0 allows for testing via modem,
or simply logging resiJts to a remote terminal, printer or
more. Run PC Probe tests in batch mode or single pass, remote or
on·slte.
laptop. You can configure your own test routines and store
THE 5 MINUTE SOLUTION TO
FLOPPY DRIVE FAILURE
With Allgnlt™ you can clBBn, diagnose, arr/ align your floppy
drives in minutes without a scope. Patented technology
requires only screwdriver to perform ANSI-accurate
alignments (.3 mil).
Alignlt is idnl for coiporate users with 2 a more PCs
because it includes a "GOLD STANDARD'' feature so you
can align all your PCs to the same in-house standard,
guarantHing that all your floppies af'B perfBctly
interchangeable between PCs.
80% of all floppy driw failures can be fixed with Alignlt so
don't replace your drive, save time and mmey instead.
Includes dual size floppies, (both high and low density) and
no-mess pre-lubricated cleaning diskettes (both sizes) good
for 180 uses. Replacements and single driw size versions
available. For al PCs and compatibles.
them in
KickStart 2's
battery
backed-up
CMOS RAM
saving
valuable setup time. Includes serial and parallel loopback
plugs and Landmark JumpStart AT ROM BIOS for testing
PCs that don't issue POST codes. KickStart 2 tests your
system regardless of OIS (even UNIX).
On-boan:l switches, LEDs, and digital displays allow
complete control over testing in systems lacking video or
disk (ideal for motherboard or system burn-in).
Kick Start 2 is the ultinate SECURITY CARD tool With both
supervisor and user l&1els of password protection, you can
prevent unauthorised use of your PC and accidental running
of destructive tests.
HARD CORE TESTING FOR
PROFESSIONALS
Landmartt/SuperSoft Service Dilgn08tica,,. is ideal for
professionals requiring the most 1xh1ustive disgnostic test
capabilities. Each module is CPU specific, including PC,
XT, AT, 386/486, and PSl2. Since 1981 major
manufacturers like W111g, Xerox, Prime, Sony, DEC, NEC,
and NCR have relied on Service Diagnostics to tackle
their tougest operating problems.
Intended for professimal service and repair technicians,
Service Diagnostics is also easy to USB for the novice.
Clear, concise on~ine help and intu~ive menus make
finding system problem; a breeze. Tests an CPUs, math
chips, all memory, flqipy, fixed and non-standard disk
drives, standard/non-undard printers, system board,
video, com ports and all keyboards. Utilities include low·
level reformat, log bad sectors, edit bad sector table; the
partition editor allows you to set up multiple partitions;
back-up program transfers hard disk image on
unformatted floppies 111d allows for restof'B after reformat.
Ideal for UNIX and other operating systems, the self·
booting version doesn't require DOS. The manual offers
troubleshooting tips to the component level. Also available
in a complete Kit including; all CPU specific software, dual
size floppy alignment software (see Ali!Pllt), and PC/XT &
AT ROM POSTs. Wl1Nr of lht PC Mlglz/M Editor's
Choice Award Jn August 1990.
lnterworld Electronics &
1000 Glenhuntly Road,
Tel: (03) 563 5011
Computer Industries (Aust) Pty Ltd Caulfield South, VIC 3162 Fax: (03) 563 5033
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Computer News
and New Products
Scanning computer
has RFcomms
A versatile, lightweight handheld
computer that integrates laser scanning
and spread spectrum communications
in a single unit is now available from
Telxon Australia.
The ergonomically designed, battery
powered model PTC-912 employs
dual CPUs for optimum performance,
one for terminal processing and the
other dedicated exclusively to RF data
communications.
The widely spaced upper numeric keys
of the PTC-912 are separated from the
alpha pad, enabling easy, single handed
use in a typical numeric application. Barcodes can be scanned automatically via
object sense logic or by triggering the
left or right handed 'scan' button.
The computer is sealed against dust
and moisture and is powered by a
removable NiCad battery pack with
built-in charging circuitry. The units are
equipped with Telxon's new 095 spread
spectrum radio, which provides clear, interference free data communications on
a dedicated network.
Also available as a scanner only,
without the RF facilities, the unit can be
upgraded to an RF unit at any time.
Laser scanner options include standard
and medium range. The standard range
version with object sense operates from
50.8mm to 508mm. The medium range
scanner is capable of reading from
127mm to 1524mm.
650MB CD image in under 15
minutes, in a package that can handle .more than 100,000 files and directories.
The software is claimed to be the most
advanced method for the production
of compact discs. Elektroson provides
the software to control CD publishing,
premastering, and CD writing. The
multisession functionality creates
enormous possiblities in document archiving, cataloging, and incremental
storage requirements.
Gear 3.0 also breaks out of ISO 9660
conventions, its optimised directory and
file structure handling allows formatting
above ISO standards. This allows file
names of up to 31 characters, and allows
nesting of up to 12 directories instead of
the standard eight under ISO.
For further information circle
163 on the reader service coupon or
contact SCSI Corporation, P.O.
Box 6888, Baulkham Hills 2153; phone
(02) 894 6033.
For further information circle 162 on
the reader service coupon or contact Telxon Australia, 4 Cambridge Street, Epping 2121; phone (02) 876 7222.
CD-R formatting
software updated
Version 3.0 of Elektroson's Gear for
Windows is claimed to be the fastest formatting software for CD-R.
Gear 3.0 can create a complete
4.2GB HDD's
for SPARC servers
Graphics Computer Systems has available SPARC Scorpion
servers with 4.2GB 3.5-inch Seagate hard disk drives, known
as Hawk-4s. These drives offer nine millisecond access time
and suit fast SCSI-2 controllers and fast, wide differential
SCSI-2 controllers.
This product is claimed by its manufacturer to be released at
least six months ahead of its opposition and will suit users running resource hungry applications on SPARC based liardware
who require additional performance now. The drivers are also
available in GCS RAID configurations for sites where non-stop
performance and speed of access is an issue.
A single ended fast SCSI-2 drive has a recommended retail
price of $5000. For further information circle 161 on the reader
service coupon or contact Graphics Computer Systems, 22
Harker Street, Burwood 3125; phone (03) 888 8522.
126
ELECTRONICS Australia, February 1995
PCB design
software update
P-CAD Master Designer 8.0 is the
latest release of a family of printed circuit board (PCB) design packages,
which operate under DOS, Windows and
UNIX environments.
The software has an improved
working environment, more flexibility,
and multiple enhancements including enhanced macro facilities, expanded
libraries, and automatic installation of
Master Designer for use under Microsoft
Windows 3.1.
For further information circle 164
on the reader service coupon or contact Quest International Computer, 5
Rocco Drive, Scoresby 3179; phone
(03) 763 8555.
Frequency synthesisers
Capable of ultra-wide band frequency
synthesis, the FSC-30 and 50 are halflength cards for any PC-XT/AT/386 that
provide up to two independent TTL level
programmable square wave generators.
Both models come with one or two
crystal controlled synthesisers per card,
with each channel independent from the
other. An optional external reference
input is also available.
Software supplied with the cards
provides either command line or popup menu selection of output frequency. Driver software is also
supplied, with source code, for
writing custom programs. An example
program is included.
The FSC-30 has a range of 0.024Hz to
30MHz while the FSC-50 has a range of
2.98Hz to 50MHz, with a resolution of
27 ,000 steps per decade. The cards have
three switchable addresses, for multiple
card use, and are connected via 50-ohm
coax with BNC connectors.
For further information, circle 166 on
the reader service coupon or contact
Boston Technology, PO Box 1750, North
Sydney, 2060; phone (02) 955 4765.
Computerised
data conversion
A new generation of compact
microprocessor based speed measurement and switching instruments from
Electromark provide information on
three levels: a speed proportional current or voltage signal; up to four
relay outputs with individually adjus-
~[ITJU oFro~@.
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Impulse
Measurement "'
Processor
•
complete kit of parts
Imp software
•
· .•
·
$229.00
$100.00*
key parts kit -all ICs. &hard to flnd parts.
No case. wire. resistors. capacitors. solder
connectors etc
$159 .00
Imp parts
Mic capsule 6mm
$9.95
A-D MAX190 IC
$29.00
PCB board only DSTHP $25.00
call for detailed listings and current
prices
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O.mo disk $5 - refundable
•prices +21 % sales tax except software.
subject to change without notice
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ME Technologies
( an ME Sound Ply Ltd subsidiary )
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P.O.box50. Dyers00$ing tfN.J 2429
• 065 50 2200, @] 065 50 2341
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A3 laser printer
with fax/modem
The 'fyphoon 20 is a RISC based 20
page per minute PostScript level 2 network laser printer with a new high speed
controller, PCL5+ emulation, resource
accounting and enhanced edge printing.
It is also the first printer to incorporate
Dataproducts' new virtual printer technology (VPT) version 3.0.
The printer's PostScript fax/modem
options tum the Typhoon 20 into a fax
machine or modem. Faxes up to A3 size
can be sent or received including spreadsheets, architectural drawings and engineering schematics at up to 800 x
800dpi. Since the Typhoon 20 is networkable, there is no need to purchase
and install fax boards, fax lines and fax
modems for everyone on the network.
Rated at 50,000 pages per month, the
machine prints at 300, 400, 600 or
800dpi in normal modes and 300E or
400E (enhanced edge technology)
modes using DpTek's TrueRes technology. This enhanced edge printing feature
improves curves and smooths jagged
edges without reducing printer speed.
The printer supports all standard paper
sizes up to A3 (297 x 420mm). Eight
megabytes of memory are included and
may be expanded up to 72 megabytes to
meet the demands of any graphic applications in the market.
Typhoon 20 pricing will start at around
$7000 (including tax).
For further information circle 165
on the reader service coupon or contact Dataproducts, 10 Rodborough
Road, Frenchs Forest 2086; phone (02)
451 3533.
VIDEO
AND
TV
FAULTS
Made Easy
Fault libraries for Australian TV &
VIDEO FAULTS are available as....
Manuals $155 + $15 delivery
(inc both tv & video)
Program for IBM compatibles
$ 155+ $10 delivery
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P.O. Box 137 Kenmore Q. 4069
Fax/Phone07 3781064
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ELECTRONICS Australia, February 1995
127
COMPUTER NEWS
table input or output points; and
an RS-232 interface for data input
and output.
The frequency/current converter and
the combined converter/frequency
relay instruments can measure variables as a function of time, such as
rotational speed, linear speed and clock
rates, which can be converted to a
proportional frequency by the appropriate pulse sensors.
All the operating parameters can be
configured locally from an integrated
microterminal. Calibration is not required. All inputs can be protected
against interference or tampering by any
unauthorised person. All the instruments
in this range are installed in a plastic
housing for mounting on tophat rails or
mounting plate to DIN standard, and
come provided with clip covers. The
products have an accuracy of 0.2% at
12-bit resolution.
For further information circle 167 on
the reader service coupon or contact
Electromark, PO Box 134, Mortdale
2223; phone (02) 533 3322.
tial flow chart (SFC) style of control that
is used by major industrial equipment
suppliers such as Allen Bradley.
Also available is a programmable control language, PLC, developed by
Procon Technology, that simulates the
operation of relay-ladder-logic control.
Finally, example programs are also
available in C, BASIC and Pascal.
The Profi Computing kit includes
three motors and gears, six: microswitches, two photo-transistors, a 20-pin
connection socket and construction
base-plate.
For further information circle 168 on
the reader service coupon or contact
Procon Technology, PO Box 655, Mount
Waverley 3149; phone (03) 807 5660. +
Computer controlled
robotics kit
Fischertechnik has released a new
robotic construction kit for use with
the IBM-PC, PS/2, Amiga and Atari
computers.
Called Profi Computing, the kit
provides 888 parts with a 164-page
manual describing the construction of 12
computer-controlled models. These
models include a cash dispenser, plotter,
CD player, parcel-turning machine and a
robot with a motor driven gripper.
The kit is useful for educational and
training purposes in the field of computer control, factory automation,
mechanical and electrical engineering.
The interface unit provides eight
digital inputs, two analog inputs and
four bi-directional motor outputs. The
unit connects to any parallel printer
port and allows a second unit to be
connected for a total of 16 digital inputs and eight motor outputs (or 16
lamp outputs).
The analog inputs can be used with
potentiometers (for position control),
light dependent resistors (for measuring
light), thermistors (for measuring
temperature) or any resistive device between 0 and 5000 ohms.
The software, called Lucky Logic,
provides an interactive, mouse-driven,
user interface that is similar to a sequen-
Australian Computers & Peripherals from JED... Call for data sheets.
Australia's first
PC/104 computer.
JJ
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The photo to the left shows the
new JED PC540 single board
computer for embedded scientific
and industrial applications.
This 3.6' by 3.B" board uses
Intel's BOC1BBEB processor,
with two serial ports (one with
2
RS485), 3 timers, R·T·clock, 1 C bus, etc. We added a Xilinx gate array
with 40 1/0 lines for user 1/0. It has 128 kB of RAM, and runs programs in
C (using the $179 Pacific C complier). Or it can run Datalight's ROM·DOS
from a 512 kB Am29F040 FLASH chip. The basic board Is $350 one-off.
$125 PROM
Eraser, complete
with timer
$300 PC PROM
<Sales tax exempt prices)
Programmer.
Need to programme PROMs from your PC?
This little box simply plugs into your PC or Laptop's parallel printer port and reads,
writes and edits PROMs from 64Kb to BMb.
It does it quickly without needing any plug in cards.
z
•
Pt Y• Ltd
JED M ICrOprOCeSSOrS
(,.)
Office 7, 517 Chandler Road, Boronia, Vic., 3155. Phone: (03) 762 3588
9
......
128
ELECTRONICS Australia, February 1995
Fax: (03) 762 5499
Transistors
(N=NPN, P=PNP, F=FETJ
2N2644
N Dual T078
45V 30mA
$4.35
2N2904 P T039 40V 600mA $1.00
2N2905A N T039 60V 600mA $1.10
2N3019 N T039 80V 1A
$1.30
2N3053 N 40V 150mA Amp $0.50
2N3069
$1.00
2N3440 N T039 250V 1A $1.45
2N3460
$3.90
2N3719
$1.30
2N37 40 P T066 60V 4A
$9. 70
2N3771 N T03 40V 30A
$6.45
2N3772 N T03 60V 20A
$6.25
2N3829 P T092 30V
$3.75
2N3903 N T092 40V 100mA$0.20
2N3904 N T09260V100mA$0.25
2N3905 P T092 40V 1OOmA $0.20
2N3906 P T092 60V 1OOmA $0.20
2N4032 P T039 80V 1A
$1.25
2N3822
$2 .35
2N3829
$1.90
2N3860
$0.55
2N3956
$12.75
2N3957
$9.25
2N4036 P T039 65V 1A
$1.65
2N4288 P T092 30V 1OmA $3.05
2N4360 PFET T092
$1.55
2N4401 N T092 60V 500mA$0.20
2N4403 PT092 40V 500mA $0.20
2N4918 PT0126 40V 1A $3.05
2N5086 PT092 50V 1OmA $0.35
2N5087 P T092 50V 1OmA $0.35
2N5210
$0. 90
2N5401
PT092 150V 600mA $0.25
2N5458 NF T092 25V 9mA $1.05
2N5459 NF T092
$1.05
2N5461 PF T092 T07110V 700u $1.50
2N5484 NF T092
$0.70
2N5485 NF T092 25V 10mA $0.70
2N5550 N T092
$0.25
2N5551 N T092 180V 10mA$0.20
2N5656 NT0126 300V 500mA $5.85
2N5871
$3.75
2N5944 407-517MHz 2W $5.50
2N5945 N 28V 7W 175MHz $5.50
2N5946 N12.SV 10W 512MHz $5.50
2N5953
$1.90
2N5961
$1.90
2N6121 N T0126 45V 4A $3.05
2N6136
$5. 50
2N6400
$1. 75
2N6401
$2.55
2N6706
$1.05
2N6710
$1.20
2N6725 N Darlington T0237 $0.85
2N7000 NF T092 60V 200mA$0. 85
8C107
N T018 40V 100mA$0.45
8C177
P T018 45V 100mA $0.80
8C178
P T018 25V 100mA $1.55
8C308-92 P T092 30V
$0.45
8C309-92 P T092 25V
$0.45
BC318
N T092 30V
$0.40
8C327
PT092 45V SOOmA $0.20
8C328
P T092 25V SOOmA $0.20
8C338
N T092 45V SOOmA $0.15
8C337
N T092 45V 500mA$0.20
8C546
N T092 60V 1OOmA $0 .15
8C547
N T092 45V 100mA$0.15
8C548
N T09230V100mA$0.15
8C549
N T092 30V 100mA$0.15
8C556
P T092 65V 100mA$0.15
8C557
PT09245V100mA$0.10
8C558
P T092 30V 100mA$0.15
8C559
PT09230V100mA$0.15
8C639
N T092 80V 1A
$0.40
8C640
P T092 80V 1A
$0.40
8D139
N T012680V1A $0.55
8D140
P T0126 80V 1A $0.55
8D202
P T0220 45V BA $2.20
8D203
$2.20
8D236
P T0126 60V 2A $0.90
8D437
N T0126 45V 4A $1.00
8D438
P T0126 45V 4A $0.95
8D439
N Power T0126
$1.50
8D440
P Power T0126
$1.50
New!New!New!New!New!New!
HAKKO 808 Portable Desolderer
READER INFO NO. 32
EA DIRECTORY OF SUPPLIERS
Which of our many advertisers are 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 readers, 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
Altronics
WA
VIC
Companion Computers
Dick Smith Electronics
ALL
Emona Instruments
NSW
NSW
Geoff Wood Electronics
Eastern
Jaycar Electronics
Kalex
VIC
Macservice
VIC
RCS Radio
NSW
Rod Irving Electronics
Eastern
VIC
Scientific Devices
TECS
VIC
Wagner Electronics
NSW
KEY TO CODING:
A Kits and modules
B Tools
C PC boards and supplies
B
A
•
•
••
••
•
••
•
•
•
••
c
•
•
••
•
••
•
D
•
•
••
•
••
Components
E
•
•
••
•
••
F
G
•
••
••
•
•••
•
•
•
•
•
•
D
E IC chlps and semiconductors
F Test and measuring instruments
G Reference books
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
SUBSCRIPTIONS: All subscription enquiries should be directed to: Subscriptions
Department, Federal Publishing Co, PO Box
199, Alexandria 2015; phone (02) 353 9992.
BACK ISSUES: Available only until stocks
are exhausted. Price A$7.50 which includes
postage within Australia only. OVERSEAS
READERS SHOULD ADD A FURTHER
A$2.50 FOR EVERY BACK ISSUE RE·
QUIRED.
PHOTOSTAT COPIES: When back issues
are exhausted, photocopies of articles can
be supplied. Price $7.50 per project or $15
where a project spreads over several issues.
PCB PATTERNS: High contrast, actual size
transparencies for PCBs and front panels
are available. Price is $5 for boards up to
100sq.cm, $10 for larger boards. Please
specify negatives or positives.
PROJECT QUERIES: Advice on projects
is limited to postal correspondence only
and to projects less than five years old.
Price $7.50. 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.
OTHER QUERIES: Technical queries outside the scope of 'Replies by Post', or submitted without fee, may be answered in the
'Information Centre' pages at the discretion
of the Editor.
PAYMENT: Must be negotiable in Australia
and payable to 'Electronics Australia'. Send
cheque, money order or credit card number
(American Express, Bankcard, Mastercard
or Visa card), name and address (see form).
ADDRESS: Send all correspondence to:
The Secretary, Electronics Australia, P.O.
Box 199, Alexandria, NSW 2015; phone
(02) 353 0620.
PLEASE NOTE THAT WE ARE UNABLE
TO SUPPLY BACK ISSUES, PHOTOCOPIES OR PCB ARTWORK OVER THE
COUNTER.
METHOD OF PAYMENT: (Please circle correct method).
Credit Card:
Cheque:
Money Order:
Mastercard
American Express
Visa
Bankcard
Expiry Date: ...................... .
Li_J
No.of issues required: ..... $7.50= ................. ..
Name: ................... :..................................... .
Address: .................................. ,.................... .
...................................... Postcode: .............. .
Back lsues: .................................................. .
No.of copies required: ..... $5.00= .................. .
No.of copies required: ... $15.00= .................. .
Total Payment Enclosed
$
=========
Photostat Copies: ..........................................
.......................................................................
Signature: ....................................................
..............................................................................(Unsigned orders cannot be accepted).
130
ELECTRONICS Australia, February 1995
ADVERTISING
INDEX
Altronics ............................. 67,Catalog
Amtex Electronics ....................... .OBC
Askey Computer ........................... JFC
AV-COMM ........................................ 75
Bainbridge Marine ......................... 118
Baltec Systems ................................... 38
BISAustralia ...................................... 17
Campad Electronics .................. .102/3
Delsound ........................................... 13
Delta Components ......................... 113
Dick Smith Electronics ................52-55
EA subscriptions offer ...................... 19
Electronic Dev. & Sales ................... 117
Federal Marketing (Books) ..... 114-115
Geoff Wood Electronics ................. 129
Hinton Information Serv................ 113
Hi-Tech Software .............................. 51
Instant PCBs ............................... .102/3
Interworld Elect.& Comp .............. 125
Jaycar Electronics ........................86-89
JED Microprocessors ...................... 128
Kalex ................................................. .15
Kepic ................................................. .38
LE.Chapman .................................. 103
Melbourne Satellites ........................ 31
Memory International ................... 121
ME Technologies ............................ 127
Nilsen Technologies ................ 117,119
Obiat .................................................. .39
Peter Lacey Services ......................... 44
Protel Technology ............................. 17
RCSRadio ................................... .102/3
Rod Irving Electronics ................ 76-79
RVBProducts .................................... 31
Scientific Devices .............................. 33
Skandia Electronics ........................ 125
TechnicalApplications .................. 127
TECS Wholesale ............................... 63
Tortech ·······-···· ............................ .102/3
Vintage Wireless Radio Co ............ 101
Vorlac ............................................... 113
This index is provided as an additional service.
The publisher does not assume any liability for
errors or omissions.
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