With we - American Radio History
MICROPROCESSOR METHODS -OUR COURSE GETS DOWN TO BASIC NUMBER THEORY
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elementaryAUGU
SIMPLY
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Electronics
BASIC
Read your
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A
DAVIS PU3LICATION
You meet the nicest people on the upper 17.
The most serious CB'ers were the first to move from 23
to40 channels. And the upper 17 are still their uncrowded
province.
President Electronics never made a CB with fewer than
40 channels. We set out fresh to meet the FCC's tough
new standards with new electronics and new ideas.
That's why every President has one of the most sophisticated compression circuits in CB-to assure consistent
100% modulation.
And why every President has power output circuits
that are vastly improved over many old 23 -channel
designs.
So when you move up,
move up to President.
And if you want to
move all the way up,
move up to the Madison-the most base sta-
and 40 lower sideband channels. And it gives you the
extra range and performance you get only from superb
SSB, with 12 watts of peak envelope power.
And it gives you all the controls you need for complete
command of everything that comes out of or goes into
the radio ...And a digital clock with alarm to remind you
of scheduled QSO's...
And a separate speaker for improved sound and improved convenience... And more.
We did, however, leave off the automatic ice maker.
Today, owning a 23 -channel CB is like
tion your money can
buy.
owning a mono record
player-great nostalgia,
but out of touch.
So get in touch with the
upper 17.
There's room.
PREsiDEnr
Engineered to be the very best.
Madison not only
gives you 40 AM channels... it also gives you 40 upper
CIRCLE 23 ON READER SERVICE COUPON
Irvine, CA
16691 Hale Avenue
In Canada: Lectron
President Electronics, Inc.
92714 (714) 556-7355
Radio Sales Ltd., Ontario
6800/2
The 6800/2 uses our new A2 processor board with socket
space for 8K bytes of ROM/PROM. This makes it possible
to use the 6800 in applications where ROM programs are
useful without purchasing an expensive PROM accessory
board. The A2 board has a DIP switch selector that allows
you to replace any 8K block of memory above the RAM
memory that extends to 32K with memory external to the
processor board itself. This lets you develop special programs that will later be put in PROM in a normal RAM
memory card where it can be modified and debugged. The
A2 board has a crystal controlled baud rate oscillator and a
separate clock driver oscillator whose frequency may be
with a programming resistor. The A2
changed
processor board gives you the maximum possible flexibility
in setting up a computer system.
SWTBUG®
Monitor-
The 6800/2 is supplied with our new SWTBUG® monitor.
This new monitor is software compatible with the earlier
Mikbug® monitor used in the 6800. All major subroutine
entry points are identical. SWTBUG® features a resident
MF -68 Minifloppy disk boot, single level breakpoints,
vectored software interrupt, generation of punch end of
tape formatting and automatic interface configuring for
either the MP -C control interface or MP -S serial interface.
ACIA Type InterfaceThe 6800/2 uses our MP -S serial interface. This RS -232 and
IS HERE
20 Ma. TTY compatible interface may be configured to operate serially at the following baud rates: 110, 150, 300,
600, 1200, 2400, 4800 and 9600. Complete interrupt control is available through the user's software.
4K Static MEMORYThe 6800/2 comes wth 4K of static RAM memory on our
MP -8M board. The memory may be expanded to 8K by the
addition of eight more memory chips. No additional parts
are needed. Full buffering of all data, address and control
lines is a standard feature. Memory expansion to 32K of
continuous RAM memory and up to a 48K mixture of
ROM/RAM is possible with this system.
ACCESSORY BOARDSa special job? Our accessory boards make it
possible to use the 6800/2 for almost any type of computer
Do you have
application. We have our MP -T interrupt timer with software interrupt selectable output. Our MP -N calculator interface that allows you to do arithmetic functions in hardware. Our MP -R EPROM programmer that programs and
verifies EPROMs right in the machine-and more coming.
6800/2 Kit
$439.00 ppd Cont. U.S.
6800/2 Assembled
$495.00 ppd Cont. U.S.
registered trademark of Southwest Tech. Prod. Corp.
registered trademark of Motorola, Inc.
SWTBUG®
is a
Mikbug®is
a
SOUTHWEST TECHNICAL PRODUCTS CORPORATION
219 W. RHAPSODY
SAN ANTONIO, TEXAS 78216
CIRCLE 26 ON READER SERVICE COUPON
ELEMENTARY ELECTIRONICS/July-August 1978
1
THE STAFF
Editor-in -Chief and
Electronics Group Coordinator
Julian S. Martin
Managing Editor
Alan H. Rose, K2RHK
Technical Editor
Neil Shapiro, WB2KQI, KAFA7222
Associate Editor
Gordon Sell, KBDA1464
Citizens Band Editor
Kathi Martin, KGK3916
Workbench Editor
Hank Scott
Art Director
Ralph Rubino
Assistant Art Director
David Pindar
Cover Art Director
Irving Bernstein
Art Assistants
Joe Groom
Celeste Barbera
Caroline Imparato
Michael Vessio
Advertising Director
David J. Miller, KCX1268
Advertising/Research Associate
Jyll Holzman, KAKZ1490
Production Director
Carl Bartee
Production Manager
Carole Dixon
Assistant Production Manager
Mary Carfagno
Newsstand Circulation
Director
Don Gabree
Subscription Circulation &
Marketing Director
Robert V. Enlow
Subscription Circulation Manager
Eugene S. Slawson
Director of Market
Development
James C. Weakley
July/August 1978
Volume 18, No. 4
-:
33
39
50
57
62
24
55
60
64
71
BUILD YOUR WAY TO FUN AND PROFIT
Mack the Tach-track your revs with this amazing phototachometer
Signal Chaser-troubleshoot your circuits and stay within your budget
Quiz Master-build this chuckles -galore quizmo
Calculator Stand-turn your calculator into a desktop demon
Love That Lettering-press-on decals make your projects look like a million
RADIO-PAST, PRESENT AND FUTURE
DX Central-increase your Q.Q.-QSL Quotient
Antique Radio Corner-build an old-fashioned, classic loop antenna
Hearing Holland-listen to a land of beauty and history
DXing Out-Of-Bounds-log the everyday excitement of the point-to-points
AM Stereo-the two -channel wave of the future
e/e CHECKS OUT TECHNOLOGICAL DELIGHTS
17 Dymek All -Wave Receiving Antenna
37 Sabtronics Digital Multimeter
41 Pennywhistle 103 Modem
67 Keymemo KM -816 Telephone Dialer
43
46
58
69
75
CELEBRATE WITH A COMPUTERFEST
You and Your Computer-things your terminal never told you
Computer New Products-a carnival of the latest computer gear
It's Simply Basic-join in the fun with this computer guessing -game
Computer Readout-liven up your knights with a chess playing computer
Our Basic Course-more on microprocessor numbering and codes
GO CB WITH CLASS AND CLOUT
49 CB New Products-get the lowdown on getting your signal out
53 Kathi's CB Carousel-spruce up your shack with a first-class rig
74 e/e Checks Out The EV Game Antenna
OUR REGULAR DEPARTMENTS
Look Me Over-what's new in the world of electronics
Hi-Fi Reports-catch up on audio with our newest department
Bookmark-by Bookworm
Ask Hank, He Knows-meet our own Mr. Wizard
Newscan-learn all about the new and unique
Hobby Mart-an electronic parts horn -of -plenty
Literature Library
8 Hey,
President and Publisher
Joel Davis
Vice President and
General Manager
Leonard F. Pinto
Vice President and Treasurer
Victor C. Stabile, KBP0681
ELEMENTARY ELECTRONICS is published bi -monthly by Davis Publications, Inc. Editorial and Executive
offices: 380 Lexington Ave., New York,
NY 10017; all subscription orders and
mail regarding subscriptions should
be sent to P.O. Box 2630, Greenwich,
CT 06835. In U.S.A. and possessions,
one-year subscription (six issues)
$6.95; two-year subscription (12 issues) $12.95; three -years (18 issues)
$18.95; and four years $23.95. Elsewhere, add $1.00 postage for each
year. For change of address, please
advise 6 to 8 weeks before moving.
Send us your current mailing label
with new address. Advertising offices:
New York, 380 Lexington Ave., New
York, N.Y. 10017, 212-949-9190; Chicago, 520 N. Michigan Ave., 312-5270330; Los Angeles; J. E. Publishers'
Rep. Co. 8732 Sunset Blvd. 213-6593810. Second-class postage paid at
New York, NY and at additional mailing office. Copyright 1978 by Davis
Publications Inc.
2
14
16
22
26
83
93
* Cover Stories
MPA
AUTHORS IN THIS ISSUE
John Boyer, James A. Fred,
Larry Friedman, Harry L. Helms,
Don Jensen, Randall Kirsch man, Kathi Martin, Norm
Meyers, Brian A. Rogers, Hank
Scott, Gordon Sell, Walter Sikonowiz, Martin Weinstein.
Cover photo by Neal Slavin
ELEMENTARY ELECTRONICS/July-August 1978
The Cobra 50XLR CB has it all.
AM/FM Stereo. Cassette. And
CB. All in one compact unit. All
engineered to bring you the same
loud and clear sound Cobra is
famous for.
The remote mike houses the
channel selector, squelch control,
and channel indicator. So all you
necd for talking CB is right there in
your hand. The cassette player features through the dial loading and
four-way fader control.
Because they're only five inches
deep, there's a Cobra in-dash radio
to fit almost any car with little or no
modification to the dash. This
feature, plus the step-by-step
Installation Manual and Universal
Installation Kit makes them the
easiest in -dash radios to install. And
our Nationwide network of Authorized Service Centers makes them
the easiest to service.
There are four Cobra in-dash
models to choose from including
AM/FM/Stereo/8-track/CB. But no
matter which you choose you can
be sure of getting the best sounding
radio going. The ul i ate car radio.
The Cobra.
obr
Punches through loud and clear.
Cobra Communications Products
DYNASCAN CORPORATION
6460 W Cortland St., Chicago, Illinois 60635
Write for color brochure
EXPORTERS: Empire Plainview, NY CANADA: Atlas Electronics Ontario
Appraveri
CIRCLE 6 ON READER SERVICE COUPON
THE ULTIMA
CAR RADIA
At CIE, you get
electronics
career
training
from
specialists.
If you're interested in learning how to fix air
conditioners, service cars or install heating
systems - talk to some other school. But if
you're serious about electronics, come to
CIE -The Electronics Specialists.
6
Special Projects Director
Cleveland Institute of Electronics
4
ELEMENTARY ELECTRONICS/July-August 1978
father always told me that
there were certain advantages to putting all your eggs in one
basket. "John," he said, "learn to
do one important thing better than
anyone else, and you'll always be
In demand."
I believe he was right. Today is
the age of specialization. And I
think that's a very good thing.
Consider doctors. You wouldn't
expect your family doctor to perform
open heart surgery or your dentist to
set a broken bone, either. Would you?
For these things, you'd want a
specialist. And you'd trust him. Because you'd know if he weren't any
good, he'd be out of business.
31y
Why trust your education
and career future to
anything less than a
specialist?
You shouldn't. And you certainly
don't have to.
FACT: CIE is the largest independent home study school in the
world that specializes exclusively
in electronics.
We have to be good at it because
we put all our eggs in one basket:
electronics. If we hadn't done a good
job, we'd have closed our doors
Plus there's a professional quality
oscilloscope you build and use to
"see" and "read" the characteristic
waveform patterns of electronic
equipment.
the exams get their Licenses. You
may already know that an FCC
License is needed for some careers
in electronics-and it can be a
valuable credential anytime.
enced specialists.
card for your FREE
CATALOG today:
Find out more: Mail this
You work with experi-
When you send us a completed
lesson, you can be sure it will be
reviewed and graded by a trained
electronics instructor, backed by a
team of technical specialists. If you
need specialized help, you get it fast
... in writing from the faculty specialists best qualified to handle
your question.
If the card is gone, cut out and
mail the coupon.
I'll send you a copy of CIE's
FREE school catalog, along with a
complete package of independent
home study information.
For your convenience, I'll try to
arrange for a CIE representative to
contact you to answer any questions
you may have.
Remember, if you are serious
about learning electronics ... or
building upon your present skills,
your best bet is to go with the electronics specialists- CIE. Mail the
card or coupon today or write CIE
(and mention the name and date of
this magazine ), 1776 East 17th
Street, Cleveland, Ohio 44114.
People who have known
us a long time, think of us
as the "FCC License
School."
We don't mind. We have a fine
record of preparing people to take
and pass ... the governmentadministered FCC License exams.
In fact, in continuing surveys nearly
4 out of 5 of our graduates who take
.
.
long ago.
Specialists aren't for
everyone.
I'll tell it to you straight. If you
think electronics would make a nice
hobby, check with other schools.
But if you think you have the
cool and want the training it takes
- to make sure that a sound blackout
during a prime time TV show will be
corrected in seconds-then answer
this ad. You'll probably find CIE has
a course that's just right for you!
-
At CIE, we combine
theory and practice. You
learn the best of both.
Learning electronics is a lot
more than memorizing a laundry list
of facts about circuits and transistors. Electronics is interesting because it's based on some fairly recent
scientific discoveries. It's built on
ideas. So, look for a program that
starts with ideas and builds
on them.
That's what happens with CIE's
Auto -Programmed° Lessons. Each
lesson uses world-famous
"programmed learning" methods to
teach you important principles. You
explore them, master them completely ... before you start to
apply them!
But beyond theory, some of our
courses come fully equipped with
the electronics gear to actually let
you perform hundreds of checking,
testing and analyzing projects.
In fact, depending on the course
you take, you'll do most ofthe basic
things professionals do every daythings like servicing a beauty of a
Zenith color TV set ... or studying a
variety of screen display patterns
with the help of a color bar generator.
-
Patterns shown on TV and oscilloscope screens are simulated.
I CIE
Cleveland Institute of Electronics, Inc.
1776 East 17th Street, Cleveland, Ohio 44114
Accredited Member National Home Study Council
YES . John, want to learn from the specialists in electronics-CIE.
Send me my FREE CIE school catalog- including details about troubleshooting
ILi
FREE package of home study information.
llcourses-plus
I
EL
my
96
Print Name
II
Apt.
Address
IICity
Zip
State
Age
,
ELEMENTARY ELECTRONICS/July-August 1978
Check box for G.I. Bill inforniation:
Mail today:
Phone (area code )
I
-
Veteran
El
Active Duty
7
distortion levels of 0.1% or less and
-52
AVANTI®
Hey,
HIGH
PERFORMANCE
C.B. ANTENNAS
40 CHANNEL ENGINEERED
ASTRO PLANETM
CB Base Antenna
Co -inductive
The omni-directional CB
-
antenna that radiates from
the top
for greater range
and performance. 4.46 db
gain over isotropic
stronger signal, clearer
reception. No coils to
burn or short. Vertical
polarity. Patent #3587109
Model AV-101...price $39.95
2.8x more power
look me over
Showcase of New Products
dB hum and noise level. Headphone jack .for monitoring unit's output.
Powered by 117 VAC, 50/60 line. Sells
for $149.95. For more details write to
Numark Electronics Corp., 503 Raritan
Center, Edison, NJ 08817.
Experimenter's VOM
The 20,000 ohm/volt compact model
110 VOM introduced by B&K-Precision is
a
16 -range fuse -protected multimeter.
For checking the low resistance of coil,
Watch Biorhythm Cycles
Many researchers have suggested that
starting from birth humans have built-in
biological clocks that vary their physical
emotion and intellectual capacities during regular repeated cycles. By simply
looking at this unique clock each day,
these cycles are shown in digital form
exactly where they are in relationship
to the individual for which the unit has
CIRCLE 51 ON
READER SERVICE
COUPON
-
transformer and motor windings, a 10 ohm mid -scale range is featured. This
E.R.P.
Avanti CB base antennas
from $20.50 to $404.00
27'
RACER
CB Mobile Antenna
Magnetic mount
CIRCLE 78 ON READER SERVICE COUPON
set. This way, you can actually
predict your good and bad days well in
advance. It lets you put off important
decisions during "off" days or to make
important decisions on "high" days. The
Personal Biorhythm Digital Clock is available factory wired for only $64.95 each
(plus $2.00 for postage and handling
per order). It is fully guaranteed and
available from Optoelectronics, Inc., P.O.
Box 219, Hollywood, FL 33022.
been
-washing. Strong
magnet
Easy to mount on roof or trunk
for car, van or truck
no holes to
fast removal for hide away
drill
or car
assures position. Mylar pad guards
vehicle finish.
Hermi-coil (Hermetically sealed coil)
special molding process
provides a weather-proof coil
environment. Helps maintain the
characteristic antenna impedance,
even in damp or salt water
atmosphere. Hermi-coil also helps
eliminate internal surface leakage.
Ribbed base
Provides a long
leakage path used in high voltage
insulators, spark plugs, etc.
-A
-
Specifications: Electrical ,/4 wave length
27 MHz
Unity gain
1.3'.1 or better
V.S. W.R.
Coil
shunt fed hermicoil
- -
Six Mike Mixer
The Numark Microphone Mixer (Model
MX3000) is a sound studio control unit
capable of handling any high power amplifier without the use of an external preamplifier. It has six mike inputs; two line
range offers better than one -ohm resolution. Resistance ranges cover 0 -Ike,
100Kí2 and 1 mego. Three DC current
ranges (0.05mA, 25mA and 250mA) and
five DC voltage ranges (0-2.5V, 10V, 50V,
250V and 1000V) are featured. DC accuracy is ±3% at full scale. Five AC
ranges (0-10V, 50V, 250V, 500V and
1000V) provide "easy -reading" measurements. The 110 is compact enough to
fit into most tool kits. Test leads and
instructions are included; a carrying case
is optional. The ohm meter requires a
common "AA" battery. The B&K-Precision Model 110 is user priced at only
$24.50 and is available for immediate
delivery at local distributors. Get all the
facts direct from B&K-Precision, 6460 W.
Cortland Ave., Chicago, IL 60635.
Budget Digital Alarm Clock
Heath Company has introduced a new
low cost digital alarm clock. The GC 1107 offers a number of features not
MODEL AV -727 Mobile Antenna System
with 48" whip, 17' coaxial cable with
magnetic mount. 40 channel $32.95
Avanti makes a complete line of high
performance mobile CB antenna systems
from $11.95 to $72.50
CIRCLE 31 ON READER SERVICE COUPON
FREE 24 PAGE CATALOG
wane
Avanti Research ít Development, Inc.
Established 1964
341)
Stewart Ave., Addison,
IL
60101 USA
creators of the
famous
©Cooynght
All
1977
res reserved
OON,RAKE
CIRCLE 54 ON
READER SERVICE
COUPON
inputs for stereo; individual mike attenuator control
switches. Stereo/Mono
switches for outputs. Master volume
control; Headphone monitor with level
control switch. The MX3000 can handle
mike inputs from 20 to 18,000 Hz with
normally found on clocks in its price
range. These include a 12 or 24 hour
time option, AM/PM indicator, automatic
dimming, a 24 hour "smart" alarm, 9
minute snooze button, power failure indication and alarm -on indicator. A 4 -digit
blue fluorescent display indicates hours
and minutes. Fast -set -ahead switches
make setting time quick and easy. The
colon separating the hours and minutes
digits flashes when the alarm has been
set. If a power failure should occur, the
hours digits flash to indicate that the
(Continued on page 10)
CIRCLE 25 ON READER SERVICE COUPON
8
ELEMENTARY ELECTRONICS/Julv-Auoust 1978
WIRE CUTTING AND
STRIPPING DISPENSER
HEY, LOOK ME OVER
(Continued from page 8)
Exclusive
"Breaker Beam"
lights when you
key your mike ...
for any good
buddy to see.
"When antenna is
recessed, beam
time must be reset. Priced at $28.95
mail order, the GC -1107 is one of many
kit products offered by Heath for the
home and shop. For more information
about this and other Heathkit produucts, write for a free catalog to Heath
Company, Dept. 350-470, Benton Harbor, MI 48922.
is not visible."
work stool and an extra shelf. The two
sections are attached side -by -side so
that all tools can be stored easily within
arms' reach. Machine cabinet and
drawer case allow organization of tools
Electricians Pocket Knives
A new
has
line of electricians pocket knives
introduced by Vaco. These
been
CIRCLE 76 ON READER SERVICE COUPON
other equipment, to avoid timeconsuming searches over the odd -sized
tables, drawers and shelves that comprise most homeowners' tool storage
facilities. The two work units are each
75 -in, high, 48 -in. across, and 24 -in.
deep. The shelves and workbenches can
easily be adjusted vertically on 2 -in. inThe
crements.
mini -shop lists for
$413.00 with individual parts sold separately. Consult factory for price list. For
further information, contact Penco Products, Inc., Oaks, PA 19456.
and
CIRCLE 84 ON
READER SERVICE
COUPON
Wire Dispenser Cuts and Strips
The new WD Series Wire Dispenser by
OK features unique cutting and stripping
capability. Wire is drawn out of dispenser
to required length. Then, built-in plunger
The Antenna
You Can
Bank On
Breaker Beam the new fully automatic AM/FM/CB antenna has all
the features you never knew existed,
and always wanted. Breaker Beam
offers more! Compare these outstanding features: 1. Turn your radio
on and the antenna goes up, turn
your ignition off and it goes down
automatically. No antennas to unscrew, nothing to flip or flop. Nothing
to "advertise" you have a CB. 2. CB
will only operate when antenna is
fully extended, eliminating transistor
blow-out. 3. Pre-tuned signal splitter
to separate frequencies. 4. Center
loading coil for maximum performance. 5. Plug-in wiring for easy installation, hardware included. 6. Totally
dependable in extreme weather conditions...and more.
Breaker Beam ... the last antenna
your car will ever need. You Can
Bank On It. Ask for further details;
see your local dealer or contact:
EVGAME
suitor)
188
company
Buffalo Avenue, Freeport, N.Y. 11520
Dept. EE
(516)378.0440
CIRCLE 34 ON READER SERVICE COUPON
10
handy, heavyduty pocket knives are
made of the cutlery steel blades. They
are tempered and hold their edge under
hard use. Their extra strong construction
features riveted shackles with steel and
brass bodies. Grip -textured plastic handles resist cracking or chipping. The
handy two -bladed model has a standard
21/2 -in.
long spearpoint blade and a
21/2 -in. screwdriver tip blade with cutting
edge. Sells for $6.25. The versatile three bladed model has a curved 23/4 -in. sheep foot slitting blade plus a 21/2 -in. spear point blade plus a 21/2 -in. screwdriver tip
blade and both models lock open for
safer, more efficient use. Sells for $7.50.
These new Vaco knives, as well as all
Vaco tools, are fully warranted. For further information, write to Vaco Products
Company, 1510 Skokie Blvd., Northbrook, IL 60062.
Mini -Shop
self-contained mini -shop that affords organization and easy access to
tools is now available from Penco Products. Called "Shoperafter," the mini shop can be used by home craftsmen,
servicemen, and do-it-yourselfers. The
mini -shop is composed of two sections,
one section includes a work bench with
drawer and a peg board back for hanging tcols; another section includes standard accessories-rollable machine cabinet, drawer case with 18 -drawer insert,
cuts length free from roll, while a gentle
pull through the stripping blade removes
the insulation without nicking the wire.
Repeat procedure removes insulation
from second end. Although designed
particularly for wire -wrapping, the inexpensive dispenser is ideal for many
applications. Dispenser includes 50 -ft.
roll of AWG 30 top industrial quality
Kynar insulated OFHC silver plated solid
copper wire. Insulation is offered in blue,
A new
white, yellow or red. Sells for $3.95.
Available from your local electronics distributor or directly from O.K. Machine
and Tool Corporation, 3455 Conner
Street, Bronx, NY 10475.
(Continued on page 12)
ELEMENTARY ELECTRONICS/July-August 1978
RADIO
BUILD
20
and Electronics Circuits
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Pat.
Off.
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RADIO-T.V. COURSE
Now Includes
12 RECEIVERS
3 TRANSMITTERS
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* SIGNAL TRACER
*
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* SIGNAL INJECTOR
* CODE OSCILLATOR
*
*
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No
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Solid State Circuits
Training Electronics Technicians Since 1946
Vacuum Tube Circuits
FREE EXTRAS
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YOU DON'T HAVE TO SPEND
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The "Edu-Kit" offers you an outstanding PRACTICAL HOME RADIO COURSE at a
rock -bottom price. Our Kit is designed to train Radio & Electronics Technicians, making
use of the most modern methods of home training. You will learn radio theory, construcRADIO COURSE IN EVERY DETAIL.
tion practice and servicing. THIS IS A COMPLETE
You will learn how to build radios, using regular schematics: how to wire and solden
In a professional manner; how to service radios. You will work with the standard type of
punched metal chassis as well as the latest development of Printed Circuit chassis.
You will learn the basic principles of radio. You will construct, study and work with
RF and AF amplifiers and oscillators. detectors, rectifiers, test equipment. You will learn
and practice code, using the Progressive Code Oscillator. You will learn and practice
trouble -shooting, using the Progressive Signal Tracer, Progressive Signal Injector, Progressive Dynamic Radio & Electronics Tester, St'dare Wave Generator and the accompanying instructional material.
You will receive training for the Novice, Technician and General Classes of F.C.C. Radio
Amateur Licenses. You will build Receiver, Transmitter, Square Wave Generator, Code
Oscillator, Signal Tracer and Signal Injector circuits, and learn how to operate them. You
Electronics.
will receive an excellent background for television, Hi-Fi andrequired.
The "Edu-Kit" is
Absolutely no previous knowledge of radio or science is
the product of many years of teaching and engineering experience. The "Edu-Kit" will
worth
many times the low
Radio,
and
provide you with a basic education in Electronics
price you pay. The Signal Tracer alone is worth more than the price of the kit.
THE KIT FOR EVERYONE
ages and backgrounds have successfully
used the "Edu-Kit" in more than 79 countries of the world. The "Edu-Kit" has been
carefully designed, step by step, so that
you cannot make a mistake. The ''Edu-Kit"
allows you to teach yourself at your own
rate. No instructor is necessary.
You do not need the slightest background
In radio or science. Whether you are interested in Radio & Electronics because you
want an interesting hobby, a well paying
business or a job with a future, you Will find
'Edu-Kit"
the
a
Many thousands
worth -while investment.
of individuals of all
PROGRESSIVE TEACHING METHOD
educational radio kit in the world.
The Progressive Radio "Edu-Kit" is the foremost
in the field of electronics training. The "Eduand is universally accepted as the standard of
"Learn by Doing." Therefore you construct.
the modern educational principle
Kit" uses
in a closely integrated prolearn schematics, study theory, practice trouble shooting-all
interesting background in radio.
gram designed to provide an easily -teamed. thoroughof and
the "Edu-Kit." You then learn the
parts
You begin by examining the various radio
radio. With this first
build
a
simple
Then
you
parts.
of
these
function, theory and wiring
learn theory, practice testing
set you will enjoy listening to regular broadcast stations,
radio, learn more advanced theory
and trouble -shooting. Then you build a more advanced
and techniques. Gradually, in a progressive manner, and at your own rate, you will
find yourself constructing more advanced multi -tube radio circuits, and doing work like al
professional ' Radio Technician. course are Receiver, Transmitter, Code Oscillator, Signal
Included in the "Edu-Kit"
not unprofessional
Tracer, Square Wave Generator and Signal Injector Circuits. These are
constructed by means of professional
"breadboard" experiments, but genuine radio circuits,
of radio construction known
wiring and soldering on metal chassis, plus the new method
These circuits operate on your regular AC or DC house current.
as "Printed Circuitr
"EDU-KIT"
THE
IS COMPLETE
and instructions necessary to bull ld twenty different radio and electronics circuits, each guaranteed to operate. Our Kits contain tubes, tube sockets. variable. electrolytic, mica. ceramic
and paper dielectric condensers. resistors, tie strips, hardware, tubing, punched metal chassis. Instruction
You
will receive all parts
Manuals, hook-up wire. solder, selenium rectifiers, coils, volume controls, switches, solid state devices, etc.
In addition, you receive Printed Circuit materials, including Printed Circuit chassis.
special tube sockets, hardware and instructions. You also receive a useful set of tools, a
professional electric soldering iron, and a self -powered Dynamic Radio and Electronics
Tester. The "Edu-Kit" also includes Code Instructions and the Progressive Code Oscillator.
in addition to F.C.C. Radio Amateur License training. You will also receive lessons for
servicing with the Progressive Sign:.l Tracer and the Progressive Signal Injector, a High
Fidelity Guide and a Quiz Book. You receive Membership in Radio-TV Club. Free Consultation Service, Certificate of Merit and Discount Privileges. You receive all parts, tools.
instructions, etc. Everything is yours to keen.
SOLDERING IRON
ELECTRONICS TESTER
PLIERS -CUTTERS
VALUABLE DISCOUNT CARD
CERTIFICATE OF MERIT
TESTER INSTRUCTION MANUAL
QUIZZES
HIGH FIDELITY GUIDE
RADIO
TELEVISION BOOK
TROUBLE -SHOOTING BOOK
MEMBERSHIP IN RADIO-TV CLUB:
FCC
CONSULTATION SERVICE
AMATEUR LICENSE TRAINING
PRINTED CIRCUITRY
SERVICING LESSONS
You will learn trouble-shooting and
servicing in a progressive manner. You
will practice repairs on the sets that
you construct. You will learn symptoms
and causes of trouble in home, portable
and car radios. You will learn how to
use the professional Signal Tracer, the
unique Signal Injector and the dynamic
Radio & Electronics Tester. While you
are teaming in this practical way. you
job for
will be able to do many a repair
your friends and neighbors, and charge
fees which will far exceed the priceof
the "Edu-Kit." Our Consultation Service
will help You with any technical prob-
lems you may have.
FROM OUR MAIL BAG
Ben Valerie. P. O. Box 21, Magna.
Utah: "The Edu-KitS are wonderful. Here
I am sending You the questions and also
the answers for them. I have been in
Radio for the last seven years. but like
Radio Kits, and like to
to work withTesting
Equipment. I enbuild Radio
with the
joyed every minute I worked
kits;
the Signal Tracer works
different
know that
fine. Also like to let you
feel proud of becoming a member of your
Radio-TV Club."
Robert L. Shuff. 1534 Monroe Ave..
Huntington, W. Va.: "Thought I would
drop you a few lines to say that I received my Edu-Kit. and was really amazed
that such a bargain can be had at such
a tow price. I have already started repairing radios and phonographs. My
me
friends were really surprised to see The
get into the swing of it so quickly.
Trouble -shooting Tester that comes with
finds
the
swell,
and
is
really
the Kit
trouble, if there is any to be found."
SOLID STATE
Today an electronics techpician or hobbyist requires a knowledge of solid state, as well as vacuum
tube
You
circuitry. The "Edu-Kit" course teaches both.
will build vacuum tube, 100% solid state and
combination ("hybrid") circuits.
Progressive "Edu-Kits" Inc., 1189 Broadway, Dept. 591DJ
PRINTED CIRCUITRY
I
increase in price, the "Edu- Kit"
now includes Printed Circuitry. You build
a Printed Circuit Signal Injector, a unique
servicing instrument that can detect many
Radio and TV troubles. This revolutionary
new technique of radio construction is now
becoming popular in commercial radio and
At
a
special insulated
chassis on which has been deposited a conducting material which takes the place of
wiring. The various parts are merely plugged
in and soldered to terminals.
Printed Circuitry is the basis of modern
Automation Electronics. A knowledge of this
subject is a necessity today for. anyone interested in Electronics.
ELEMENTARY ELECTRONICS/July-August 1978
Hewlett, N.Y. 11557
Please rush me free literature describing the Progressive
Radio-TV Course with Edu-Kits. No Salesman will call.
no
TV sets.
A Printed Circuit is
TOOLS
I
I
I
I
I
NAME
I
ADDRESS
I
I
CITY & STATE
I
ZIP.
I
PROGRESSIVE "EDU-KITS" INC.
11
I
1189 Broadway, Dept. 591DJ
CIRCLE 17 ON READER SERVICE COUPON
Hewlett, N.Y. 11557
I
1
11
Measure
resistance
to 010.
pm-
HEY, LOOK ME OVER
(Continued front page 10)
Foolproof Remote Station
An attractive, low-cost coded pushbutton
remote control station by Mountain West
Alarm Supply Co. eliminates the use of
keys and the risk of lock picking. This
unit operates momentary contact controls and is usable with many popular
control panels without complicated wiring hookups or special power considerations. The new D14 pushbutton alarm
layouts. The breadboard area on the
Proto -Board 203 includes enough tie
points to support 24 14 -pin DIP ICs.
Four binding posts provide power and
signal connections on and off the board.
The built-in power supply is 1% regulated
at 5 ±.25 Volts, rated at 1 A, and boasts
a low 10 millivolts combined ripple and
noise at 0.5 A out. And it's short -proof.
The 51/2 -pound package measures 93/4 -in.
long, just over 61/2 -in. wide and 31/4 -in. tall.
CSC's low suggested resale price for the
PB -203 is just $80.00 (per unit). Further
information is available from CSC dealers and distributors, or direct from Continental Specialties Corporation, 70 Fulton Terrace, New Haven, CT 06509.
CIRCLE 57 ON
READER SERVICE
COUPON
at a price that has'no resistance at all.
digit bright LED display
100µ V, .0152 resolution
0.5% accuracy typical
31/2
Autozeroing
Completely overload protected on all 29 ranges
RFI shielded for use in RF
fields
100% overrange reading
Selectable high -/low -power
ohms
Full range of optional accessories available
control features a replaceable, pre-programmed code key which is field changeable. Each time the correct code is entered on keyboard, a solid state momentary switch operates. The keyboard has
tactile feedback pushbuttons which are
reported to be rugged, yet easy to
operate. Uses low input power, less than
2 mA standby at 6 to 24 VAC or DC. Has
red and green diode status lights. Unit
Powered Breadboard
TTL logic system designers are finding
attractive design shortcut available to
them, thanks to the Continental Special ties Model PB -203 Proto -Board, a high
capacity solderless breadboard that inan
buy" among DMM's currently
CIRCLE 83 ON
READER SERVICE
COUPON
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DYNASCAN
CORPORATION
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In Canada: Atlas Electronics, Ontario
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Plainview, LI, NY 11803
CIRCLE 22 ON READER SERVICE COUPON
12
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weighs only 7 ounces, is 47/8 -in. x 31/2 -in.
x 11/8 -in. Case is formed from beige, high
impact plastic. Surface mount unit is
priced at $53.00 each. For more information, contact Mountain West Alarm
Supply Company, Box 10780, Phoenix,
AZ 85064.
At $119.95, the 2810 is a "best
available. Its 10 ohms range
allows you to check the low
contact resistance of switches,
relays, breaker points or connectors. Poor solder connections can also be spotted. Place
your order now...contact your
local distributor for immediate
delivery.
Stereo Headphones
Audio-Technica has a new series of five
stereo headphones with moving coil dynamic and electret condenser models.
The new stereo headphones, called the
ATH series, have a two-part headband
for optimum comfort and fit. The outer
band is stainless steel for strength and
light weight. An inner band of soft synthetic suede conforms to the head, distributing weight evenly and making the
physical contact of the headphones
slight. The headsets use spring -loaded
ball bearings for smooth adjustments.
Ear cushions of soft, porous vinyl prevent uncomfortable heat build-up. The
lightweight cord is flat to resist tangling.
cludes a built-in 1% -regulated 5 VDC
power supply. The advantage to a TTL
hobby designer is the ability to design
directly in hardware, assuring proper
circuit operation, before hand wiring.
This helps prevent the confusion in
translating from gate schematics to actual IC packages, often providing valuable insight into ways of simplifying PC
The new line of headphones offers two
electret condenser models, the ATH-6
and ATH-7 (shown). Both use low -mass
diaphragms just five microns thick offering top transient characteristics and unusually wide, uniform frequency response. The ATH-6 ($99.95) offers a
frequency response of 20-22,000 Hz, ±3
decibels from 40 to 22,000 Hz. The ATH7 ($149.95) has a frequency response
of 10-22,000 Hz ±2 decibels from 20 to
22,000 Hz. The ATH-7 has an LED indicator to signal high-level peaks and
warn of possible overload. Audio-Technica has nicknamed the ATH-1 ($29.95)
"The Gram Cracker" because of its extremely light weight: just 135 grams
(4.75 ounces), less cord, and 190 grams
(6.7 ounces) total. The ATH-1 uses an
unconventional "planar moving coil" and
has a 30-20,000 Hz frequency response.
The ATH-3 model ($59.95) offers a frequency response of 25-20,000 Hz. The
electrical system of the ATH-5 ($79.95)
uses a light, compliant dome diaphragm
for extended bass and treble response
and a smooth, uncolored sound. The
frequency response is 20-20,000 Hz.
(Continued on page 91)
ELEMENTARY ELECTRONICS/July-August 1978
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Every Heathkit product comes with a fully illustrated, step-by-step assembly manual that
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ELEMENTARY ELECTRONICS/July-August 1978
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Gordon Sell reports on Pioneer's
new low -end tuner and amplifier,
and Shure's new super cartridge
It's no game! When you need
ICs for your project, move
at once to Hobby Mart, the
hobbyist's special advertising
section in the back of
ELEMENTARY ELECTRONICS.
Prices are right, selection is
large, and you're only a postage stamp away from your
fully -stocked supplier.
Need
parts?
Find them
MART-page 83.
in
HOBBY
Cramped
for Antenna
space?
Whether you plan to spend $200 or
$2000 on a high-fidelity stereo system
you are going to have to make some
compromises. Of course if you have a
$2000 hi-fi budget I can't really feel
very sorry for you. If your budget is
closer to $200, however, the situation
is tough but far from hopeless. You can
fill your home with quality sound without draining your bank account-all it
takes is a bit of careful planning.
Lately budget hi-fi has meant buying
one of those jack-of-all-trades, 1ttasterof-none machines; you know the kindan AM/FM radio with a record player
on top, a tape player in the side, walnut
vinyl on cardboard speakers and a
built-in egg timer and coffee grinder. In
the trade they call these "compacts." I
suspect it's because they usually end up
in the compactor. If you can only just
afford one of these you haven't saved
long enough. Unless you don't intend
to play anything other than scratched
up old 45s, keep packing away those
pennies-good sound is not too far out
of reach.
The McKAY DYMEK DA 100.
The DA 100 is a compact, wide dynamic
range, broadband, untuned, omni-directional receiving antenna covering the
frequency range of 50 kHz to 30 MHz.
The exterior module, a small weather-proof
box with a 56 inch (142 cm) whip delivers
the signal to the power supply unit through
a supplied 50' coaxial cable.
The power supply locates near your
general coverage receiver and attaches
with a supplied patch cord.
The DA 100 antenna is small, but will equal
or outperform a 100' long wire antenna,
and is priced within reach of everyone!
Output Impedance - Attenuator SwItch
provided to match receiver input
requirements and prevent overload.
Order factory Direct. Call toll free today!
Money Back guarantee. Rent/Own Plan
available. Specs and details on request.
Nationwide 800/854-7769
California 800/472-1783
McKay Dymek Co.
j111 S. College Ave., PO Box 5000
Claremont CA 91711
14CIRCLE
19 ON READER SERVICE COUPON
Pioneer TX -5500 II
CIRCLE 63
ON READER SERVICE COUPON
Now, thanks to some companies who
appreciate that most hi-fi buffs can't afford to drop $700 for a stereo amplifier, there are alternatives to the jackof-all-trades ear-itator. Component
stereo systems can be found with prices
as pleasing as their sound and with
these systems you don't have to buy
everything at once. This is the real
beauty of component-hi-fi-its ability to
grow with your budget and your ever
expanding appreciation of fine music.
Tuning in. Pioneer has just introduced
a couple of new products that I thought
would be of interest to the hi-fi buff on
of a first class stereo system. You may
end up trading them in or giving them
to your kid brother in a few years but
they will get your hi-fi system .off the
ground. After all, you have to learn to
walk before you can run, and going in
to fancy hi-fi too fast is a sure way to
stumble.
The Pioneer TX -5500 II AM/FM
stereo tuner and SA-5500 II stereo amplifier are two nice-looking units. They
make your hi-fi corner look as good as
it sounds, when you hook them up to a
pair of efficient speakers.
The TX -5500 II tuner has a very
simple but attractive front panel with a
combined AM signal strength and FM
center tuning meter. Tuning is aided by
a stereo indicator light and a hefty flywheel tuning knob. A single function switch controls FM muting and AM/
FM selection. On the rear apron there
are the usual output jacks plus an FM
de -emphasis switch, and lugs for either
75- or 300 -ohm impedance FM antennas and an AM antenna input. The set
has an internal AM loop.
Our test labs checked out this unit
(as they do every product e/e reviews)
and found its performance was quite
good for a unit in this price range. In
the FM tuner section the signal-to-noise
ratio' was an excellent 70 dB and the
stereo separation was 40 dB. The
THD (total harmonic distortion) measured a respectable 0.5% stereo and
0.22% mono.
At the standard test aevel the stereo
frequency response, with 75-uSec de emphasis, was measured at +0/-2 dB
from 20 to 20,000 Hz. Full limiting was
attained with a 4-uV signal. The high
fidelity sensitivity was 6-uV for mono
with 60 dB quieting and 100-uV for
stereo with 55 dB quieting. Full mute
release was attained with 2.5 uV.
About the only fly in the ointment
was some 19 kHz stereo pilot leakage
(only 39 dB down). If you are using a
Dolby for tape recordings it should be
a model with a built-in or switch-selected mpx (19 kHz) filter. AM performance is about average for this type
of tuner although I wonder how much
this matters-I've never met anyone who
listens seriously to AM on a hi-fi system.
The TX -5500 II carries a suggested
retail price of $150 and is available
with a good looking walnut (real wood
not vinyl) veneer wooden case for an
extra $30.
Amplification. Although Pioneer's
TX -5500 II could be mated to any
standard amplifier it will be well worth
your time to take a hard look at its
partner component, the SA -5500 II
stereo amplifier. Matching components
tend to add a certain amount of class
to a hi-fi corner but this is far from the
ELEMENTARY ELECTRONICS/July-August 1978
only reason.
Pioneer has provided the SA-5500 II
with a large, 41 -stop click-detent volume knob, ganged bass and treble controls, a three -position function switch,
loudness and tape monitor switches and
pushbutton controls for two sets of
speakers.
Pioneer SA -5500 II
CIRCLE 63 ON
READER SERVICE COUPON
Using Federal Trade Commission
guidelines, Pioneer conservatively reports the SA -5500 II's output at 15
watts RMS per channel with less than
0.5% THD between 20 and 20,000 Hz.
On our test bench the unit did better;
checking in with 0.2% THD in the
same power and frequency range. The
frequency response was +0/-0.2 dB
from 20 to 20,000 Hz, magnetic input
hum and noise measured -67 dB, the
stereo separation was 63 dB and the
tone control range measured +9/-9.5
dB at 50 Hz and ±7.5 dB at 10,000 Hz.
If all of the above means something
to you, great-if not, don't get upset.
Basically it means that this amplifier,
pushing two efficient 8 -ohm speakers,
will force you to shout to be heard at
10 watts and will probably get you
evicted if you leave it on 15 watts continuous output. Don't try to use the
argument that the sound was 99 44/100
percent distortion free-landlords are
notoriously tone deaf. What is important about SA -5500 II is that it will
provide an adequate volume of good
quality sound in a normal room -sized
environment, and even drive a second
set of efficient speakers.
In a few years, when you find that
you want more power to drive some
larger speakers and you want to brag
about your subatomic distortion figures
to your friends, you can trade -up to a
more powerful amp without having to
replace your whole system at once. With
a suggested retail price of $125 you
can't go far wrong with this durable
Pioneer unit. As with the TX -5500 II
a wooden case is available for $30. For
more information on the Pioneer TX'5500 II and SA -5500 II circle No. 63
on the reader's service coupon.
Upgrading Your System. If you already have a low to medium priced hifi system you have probably been trying
to figure out how to upgrade your
sound. This is no easy task since it is
often very hard to figure out what part
of your system is the "weak link" in the
chain.
Since.I don't know where to start on
your system I'll start at the beginning of
the audio chain which, in most cases,
is where the phono needle, or stylus as
it is usually called, is dragged along the
groove of an LP. This seemingly simple
action is probably the most troublesome
area in the whole hi-fi field.
A stylus has to be unbelievably durable and delicate at the same time. It
must be tough enough to survive being
dragged across a quarter -mile of plastic
for each side of a 12 -inch LP. If you
listen for an hour a day your stylus will
chalk up between 350 and 400 miles
a year (more than some people walk).
This durability has to be combined
with the sensitivity needed to reproduce
the entire audio spectrum (and more if
you go in for four channel) and be
gentle enough not to destroy a record
after just a few plays. This area is a
prime target for improvement on almost
any audio system.
The Shure Brothers of Evanston, Illinois, who have been making stereo cartridges and stylii for many years have.
just released the latest product of their
extensive R&D department: the V15
IV stereo cartridge with hyperelliptical
stylus.. The footprint (area of contact
with the LP) of this stylus is narrower
than .the traditional biradial (ellipitical)
stylus and is also symmetrical to help
reduce intermodulation and second harmonic distortion. The stylus is mounted
on a very low-mass shank (0.29 milligrams versus 0.33 milligrams on the
V15 III which it replaces) and fitted
with low-mass magnets. This provides
a measurable improvement in tracking
performance, particularly in the middle
and upper frequencies.
Shure V15 Type IV
CIRCLE 65
ON READER SERVICE COUPON
In the Groove. The Shure V15 IV has
one other major improvement that
helps its tracking performance and combats wow and flutter (frequency oscillation). Shure calls it a Dynamic Stabilizer-I call it the ultimate dust brush,
which is what it looks like. This nifty
little gadget is mounted to provide a
negative tracking force of 0.5 grams
which holds the cartridge at a fixed
distance from the record and keeps the
stylus shank at a constant angle.
A cartridge/stylus system and the
ELEMENTARY ELECTRONICS/July-August 1978
(Continued on page 91)
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Brand new! Exciting! 112 pages,
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EXTRA! You'll also get with this
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Y
Amongst a lot of other exciting
stories, you'll enjoy a novelette by
Poul Anderson ("Capture of the
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short story by Dr. Asimov himself!
ASIMOV'S
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FREE '78 EICO CATALOG
Check reader service card or send 50r
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prehensive volume. Well-known author Clifford tells all about the many different types
of microphones and accessories available,
explains how to get the most out of microphone "spec" sheets, and how to interpret
polar patterns. Beginning with a brief historical background, the book explains the
development of a practical microphone,
and details why present-day units have certain electrical characteristics, covering the
many factors and design variations that
affect the quality and response of various
microphones. Published by Tab Books, Blue
Ridge Summit, PA 17214.
Way to Learn. The most widely used IC
the operational amplifier. If you are not
familiar with the op amp, then The Design
THE
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phones and shows how to record almost
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It clearly explains how to get different sound
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of Operational Amplifier Circuits, with Experiments by Howard M. Berlin is the book
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operation of basic operational amplifier
circuits coupled with a series of over 35
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16 CIRCLE 45 ON READER SERVICE COUPON
Chips to Systems. Microprocessors by
is an introduction to
microprocessors and microcomputer systems. It presents both the concepts, and the
actual techniques and components used to
create systems. It introduces the reader to
the aspects of system operation, use, and
design. Some of the topics covered are: a
comparative evaluation of all major micro-
Dr. Rodney Zaka
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introduction
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An
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Soft Cover
416 pages
$9.95
from chips to systems
processors, a journey inside a microprocessor chip, how to assemble a system, interfacing the 5100 bus and programming. No
prior electronic or computer training are
necessary. Published by Sybex Inc., 2161
Shattuck Avenue, Berkeley, CA 94704.
Solid-State Replacement Guide. The
of the RCA Solid State Replacement Guide is now available for electronic experimenters. The 240 -page book,
SPG-202W, can also be used by engineers,
servicemen and others who work with solidstate devices. The comprehensive RCA SK
line of replacement transistors, rectifiers,
thyristors, integrated circuits and high voltage triplers has grown to over 150 devices,
including 387 SK- which have been added
1978 edition
Need a part? This
book is the place
to look.
The Design of
Soft Cover
240 pages
$1.50
Operational
Amplifier
Circuits, with
Experiments
How to design op
amp circuitry.
Soft Cover
277 pages
$9.00
to the line since February 1977. The 750
devices replace over 141,000 domestic and
foreign industry devices. The 1978 RCA
PROJECTAPIX, LTD.
300 WEST 53 STREET
NEW YORK. N.Y. 10019
meant to be a sourcebook of all available
op -amp circuits, nor a textbook covering the
performance characteristics of the various
types that are available. However, this is a
text/workbook that explains the design of
the fundamental circuits that are the building blocks of the more sophisticated systems using many op-amps. For this reason,
this book is useful to the beginning experimenter and hobbyist who wants to learn
the basics by self study. Published by E&L
Instruments, Inc., Derby, CT 06418.
experiments to illustrate the design and operation of linear amplifiers, differentiators
Solid State Replacement Guide can be obtained from your local RCA distributor or
by sending a check or money order (no
cash or stamps) to RCA Distributor and
Special Products Division, P.O. Box 85EE,
Runnemede, NJ 08078.
ELEMENTARY ELECTRONICS/July-August 1978
e/e checks out the...
DYMEK DM00 ALL-WAVE
RECEIVING ANTENNA
This
help
your
from
CIRCLE 58 ON
handy gadget will
you hear more from
receiver and less
your landlord.
and
DXers find that the landlord's regulations often preclude the use of a decent
receiving antenna. In many buildings,
nothing other than the landlord's master
TV antennas can be installed on the
roof; this often means the SW antenna can be no more than a short
whip mounted on a terrace, or window
ledge, or a short length of wire hanging down from the window, whose reception sensitivity varies as the wind
blows the wire towards and away from
the building.
Features. One good answer to the
problem of no space for an antenna is
the Dymek DA -100 All Wave Receiving Antenna, which is basically an automobile type antenna mounted on a
weatherproof box with an encapsulated
transistorized amplifier inside the box.
The complete DA -100 system consists
of the weatherproof housing, the autotype telescopic antenna that mounts on
the box, fifty feet of RG -58 coaxial
MANY SHORT-WAVE LISTENERS
READER SERVICE
COUPON
cable that brings the signal down from
the amplifier and which also carries the
DC power, an indoor control box that
contains the power supply, an antenna
switch that selects either the signal from
the preamplifier or an auxiliary wire
antenna, and an "output impedance
matching" switch that provides output
impedances of 50, 100, and 500 ohms.
The switch can also be used as a 0, 10
and 20 dB attenuator if needed to compensate for strong stations.
The operating frequency range of the
DA -100 is 50 kHz to 30 MHz. The
internal amplifier provides approximately 3 dB gain at 100 kHz falling to 0 dB
at 1 MHz, again rising to approximately
+11.2 dB at 20-25 MHz, and then falling to +8 dB at 30 MHz. Between 100
kHz at 50 kHz the gain falls from +2
dB to -6 dB.
The DA100 system is touted as a replacement for a 1000 foot antenna. As
any SWL and DXer should know,
length does not necessarily mean "gain,"
AUX. ANTENNA
A standard UHF connector is used for the
coax running to the
amplifier and phone
type jacks are used
for both the output
to the receiver and for
the auxiliary wire antenna. 115 or 220 VAC
OUTPUT TO
RECEIVER
INPUT FROM ANTENNA
AND AMPLIFIER
ELEMENTARY ELECTRONICS July -August 1978
or received signal strength, because signal strength does not necessarily depend
on the length of the wire used for the
receiving antenna. At some frequencies
1000 feet might be ideal, at others it
might prove a disaster because of multiple nodes.
Rather than considering the DA100
a substitute for 1000 feet of wire, it is
best to consider it as the solution to
difficult antenna installations such as
mentioned at the beginning of this
article. For example, you cannot beat
the DA100 with any other "all band"
window antenna. Angled outward from
the window the DA100 performs as
well as a "car radio" whip at the lower
frequencies, and as an amplified whip
at the higher frequencies. If you have
a terrace you can mount the weatherproof box and antenna on the metal
railing (the further away from the
building the better). If you can get the
antenna up on the roof, and find you're
short of cable, you can simply add 50
ohm coaxial cable extensions, or use
one of the pre-fab coax extensions.
Fitting it in. The total antenna height
when extended is 4 -ft. 8 -in. The
weatherproof housing is a standard electrical "outdoor/weatherproof" box specially modified with the antenna mounting on top and a weatherproof coax
fitting on the bottom. The indoor control box measured 9 -in. wide by 5 -in.
high by 9 -in. deep.
The Dymek DA -100 system complete
with 50 feet of 50 ohm coaxial cables
is priced at $135.00. For additional information circle No. 58 on the reader's
service coupon.
17
25 million reasons
into NRI training in CB and
The CB boom means
big opportunities for
qualified technicians...
learn at home
in your spare time.
There are more than 25
million CB radios out there,
millions more two-way radios,,
walkie-talkies, and other communications apparatus in
use by business and industry,
government, police and fire
departments. And all of this
equipment demands qualified
technicians to maintain and
repair it. In addition to knowing what you're doing, you
must have an FCC Radiotelephone License to service most
of it. NRI can help you get
both ... the training and the
license.
Learn on your own
digitally synthesized
VHF transceiver or
40 -channel CB.
2 -meter,
With NRI, you learn by doing.
You use the NRI Discovery LabN to
build and test a whole series of typical
communications circuits, even assemble
your own professional transistorized
volt -ohm meter and a CMOS digital
frequency counter. You test various
types of antennas to gain a firm understanding of broadcasting principles.
And finally, you assemble your own
2 -meter transceiver for experiments
in troubleshooting and servicing.
Then, if you want to go on the air,
we'll help you get your amateur
license. As an alternate choice, you
may elect to receive and experiment
with a 40 -channel CB to get more
experience in this booming area.
T
Some designed-for-learning equipment you get.
18
1Ttademark McGraw-Hill
You learn in your own home,
in your spare time, at your convenience. NRI's bite -size lessons and
carefully matched practical experiments combine theory and bench
work to give you the most effective
training for your money. No need to
quit your job or take night classes,
you move ahead at the pace that
suits you best.
NRI
guarantees your FCC license.
The law requires that technicians hold an FCC Radiotelephone
License to work on broadcast equipment. NRI training in Complete
Communications Electronics or our
CB Radio Specialist course is,carefully
designed to give you the special
coaching so helpful in passing FCC
license exams. If you fail to pass the
FCC examination for radiotelephone
license after graduating, NRI will refund your tuition in full. The moneyback agreement is valid for six months
after completion of your course.
Send for free catalog.
No salesman will call.
Find out all the facts about
NRI's Communications or CB course.
Or look into other areas of opportunity like TV and audio servicing, digital
computer electronics, mobile communications, and more. Mail the postagepaid card today... there are more
than 25 million good reasons why.
ELEMENTARY ELECTRONICS/July-August 1978
why you should look
Communications Servicing.
Or get into
TV and audio servicing
NRI can train you at home to
service TV equipment and audio systems. Choose from five courses that
go up to our 48-lesson Master Color
TV/Audio Course. With it you get
14 kits for practical bench training
and demonstrations, including NRI's
exclusive, designed-for-learning,
25" diagonal solid state color TV,
4 -channel audio system complete
with speakers, and professional instruments you build and use for learning and earning. It's proven, effective
training that's helped thousands of
pros already. And it's the best value
offered in the field. NRI's bite -size
lessons speed learning, exclusive
Ypu get more
for your money from NRI.
"Power-On" training makes it real.
Send card for free catalog.
Learn computer electronics
trains you at home
on a real digital computer.
NRI
Qualified technicians are
urgently needed
for careers in
the new field
of computer
and digital
electronics ...
and NRI trains
you at home
on the real thing.
NRI instructor/engineers
Each NRI student is assigned
his own course instructor. He's there
to help you over any rough spots, explain problems, and give you the advice you need as you progress toward
your future. And he knows what he's
talking about, because he was more
than likely involved in the design
of your course or some of the NRI
equipment you use. NRI instructors
are practical, experienced people who
really know their field and do their
best to pass their knowledge on to you.
As
part of your training, you actually
assemble a working digital computer
with expanded memory, define and
flow chart programs, code your program, store it along with data in the
memory bank. It's just one of the 10
hands-on training kits you receive.
You also build and use your own
TVOM; experiment with NRI's exclusive electronics lab. It's the quickest
and best way to learn and start a
new career in troubleshooting digital
computers. Send the card today.
Illikiiiiiii
NRI employs no salesmen, pays
no commissions. We pass the savings
on to you in reduced tuition, topquality professional equipment, and
reliable testing instruments necessary
for a successful career. You can pay
hundreds of dollars more at other
schools, but you can't get better
training.
Free catalog,
no salesman will call.
Get your free catalog and discover why NRI is the leader in home
technical training with over a million
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helping people build new careers.
Mail the card today and get started
on your new future. If card has been
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NRI
wir,e
LiliLal
111IY
NRI SCHOOLS
McGraw Hill Center
for Continuing Education
3939 Wisconsin Avenue
Washington, D.C. 20016
ELEMENTARY ELECTRONICS/July-August 1978
21
WIRE CIRCUITS FASTER
WITH SOLDER-THRU PENCIL WIRING
VECTOR P178-1
Got a question or a problem with a project-ask
Hank! Please remember that Hank's column is
limited to answering specific electronic project'
questions that you send to him. Personal replies
cannot be made. Sorry, he isn't offering a circuit
design service. Write to:
NEW IMPROVED TOOL
Makes solder
Hank Scott, Workshop Editor
ELEMENTARY ELECTRONICS
380 Lexington Avenue
wrapped
connections 3 times
faster than usual
way.
New York, NY 10017
Quick -melt
insulation for
clean, fast
solder joi
with 75"'
iron.
In the Mix
When 1 transmit on CB, my nearby
AM radio picks up shortwave stations
such as Voice of America, Radio Moscow
and Canada International. What causes
this?
-R.C., Martinsburg, WV
snap -in
Easy thread
& finger
strolled
t. nsion &
at.
ance.
SI: m,
light,
co nfortab le ip
angle.
4
tà
.:
',Mrs
unavailable locally, factory order. Add
$2.00 shipping and handling charge.
California residents add 6% sales tax.
1f
VECTOR ELECTRONIC COMPANY, Inc.
12460 Gladstone Av., Sylmar, CA 91342
phone (213) 365-9661
twx 910-496-1539
CIRCLE 38 ON READER SERVICE COUPON
he Answer
For...
tudent
Hobbyist
nufacturer
8700 Processor: 6503 MPU.
Wear free
"Active Keyboard", Micro -Diagnostic®, Extensive
documentation, Fully Socketed.
Piebug Monitor:
User Subroutines,
Relative address calculator, Pointer High -low,
Back-step key.
Interface:
Cassette
x.
Load
s Dump by
file
Positive indication of operation. Tape
motion control.
Applications systems from $90 (10unit quantity)
Development systems from 5149 (single unit)
TELL ME MORE
I want to see for
myself that the 8700 is The Answer.
(
Please send documentation $10 enclosed.
(
i send price lists & FREE Catalog of other
PAIA kits.
name:
Address:
City:
zip
State:
1
gm
DEPT. EE
ELECTRONICS
22 CIRCLE 15 ON
6
1020
*Oklahoma City,
W.
Wilshire Blvd.
OK
73116
READER SERVICE COUPON
Possibly your CB signal and shortwave
signal are mixing in the first RF stage of
amplification in your receiver. Since the
signals are strong, non-linear rectification
occurs which is ideal for signal mixing.
The difference signal falls into the AM
band range and your set responds to it.
The discussion is very general because the
exact technique for this to happen can be
caused many ways. I suggest you look
seriously into shortwave listening and buy
a good SW receiver.
Junky Noise
Hank, in your Fall-Winter 1977 issue of
ELECTRONICS HOBBYIST an item in your
column by HW of lay, New York complained of windshield motor wiper noise
on his 1974 Subaru. I have a similar car
and the noise problem on CB is very bad.
The noise comes from the wiper motor, the
radiator fan (electrical), gas pump, and
ventilating blower motor. In -line capacitors are needed in all of these to reduce
the noise. Also, the alternator in the low
speeds (1st, 2nd, 3rd gears) gave quite a
bit of noise, 4th speed seems to be too
high a frequency for the CB set to pass.
Incidentally, all these items caused a considerable amount of noise in the AM
radio set also. Installing the aforementioned capacitors has cleaned this up too.
(The AM car radio is a piece of junk
anyway). The only difficulty I found in
clearing the noise on the ventilating blower motor was that there was not a piece
of metal to ground the case of the capacitors within a foot or so
everything is
plastic near the motor. Another item also
is to use a piece of coax cable run directly from the battery to the CB set. This
shielded power lead helps a great deal.
-R.S., Pawling, NY
...
Thanks for the tips. Too many makers
of cars are "RF defective." The FCC is
looking into this matter to prevent the
millions of autos in the U.S. from polluting the radio bands. The coax idea is good,
but be sure to fuse the hot line near the
battery.
Ups and Downs, Ins and Outs
1 have a shortwave receiver that acts a
little funny. 1 don't know if it's normal
or not, but the signal keeps fading and
building up again. 1 have to keep turning
up the volume when it's weak; and down,
when it's strong. What's wrong?
-D.D., San Francisco, CA
little reading on basic shortwave
propagation will explain that shortwave
signals do fade in and out causing the
kind of reception you are experiencing.
Receivers have an AGC (that's Automatic
Gain Control) that works to prevent this
from occurring. Some sets can turn the
AGC off. See that the AGC (sometimes
called AVC) is turned on, if it is switch able in your receiver. Extreme signal
fading cannot be remedied by AGC and
you will continue to hear fading of signals. That's what SWL is all about.
A
8080 Beginner
Could you please tell me where I can
obtain the schematics and parts lists for
the 8080 and 8080A microcomputers?
Thank you.
-D.M., Chandler, AZ
Don't know why you limited your plans
to the 8080, for there are other microprocessor chips on the market that are
worthy of consideration. Why not contact
the Heath Company (see ad in this issue)
and ask for info on their computer kits.
Also, look to Southwest Technical Products (ad also in this issue) for ,their
literature. Further, read the computer column each issue written by Norm Meyers.
If I were you, I'd do a lot of reading
and researching before actually investing
in a computer system that is home brew.
Another Way
Is there any place that will design a
P.C. board from a schematic diagram?
1 am involved with a few projects and
would like then[ mounted on a P.C. board.
I've tried to design them myself but run
into problems. Does anyone offer this
service?
Go
-S.S., North Platte, NE
What you need is a solderless breadboard. Why not write to Continental
Specialties Corp., 44 Kendall Street, New
Haven, CT 06509 (West Coast readers
write to 351 California St., San Francisco,
CA 94104) asking for their catalog. You
could also write to AP. Products, Box 110,
72 Corwin Drive, Painesville, OH 44077.
Solderless breadboards are good because
you can build on them, troubleshoot, make
design changes and even use the assembly'
as it is. Another trick is to trace out a
printed circuit template, from the layout,
that works on the solderless breadboard.
You may be able to simplify a bit, then
you may not. Try to work out ununecessary jumpers for "art's" sake, but then
it's not critical to the operation of the
circuit or construtcion. Try solderless
breadboards, they are terrific. As for a
ELEMENTARY ELECTRONICS/July-August 1978
design service, if you don't know a local
experimenter, forget the service, the price
is too high.
This is easy anyone can solder-
Tain't So!
I have a question about a TV game
kit I plan to build. I recently heard from
a friend that TV games can eventually
damage a TV set. Is this really true?
Should I build the kit?
-P.C., Arlington, VA
H
KESTERWITSOLDER
r
You should experience no troubles with
your TV set. This problem first occurred
and has since been solved. You will not
burn any designs into the tube face.
Funky Counter
Would it be possible to connect a VOX
system to a digital counting circuit so that
one count is advanced for "every sound"
picked up by the microphone?
-E.B., Kearny, NJ
-
Q
Handymen! Hobbyists!
DO-IT-YOURSELFERS!
Yes, once you define what "every sound"
that a sensing circuit could be built!
PRO -2001 Update
Readers should know that, on the PRO 2001 programmable scanner which we
reported on last issue, there is a way
to resume search after a frequency is
entered into a channel without reprogramming LO and UP. Simply: 1) press
MONITOR to stop the scanning action,
2) press ENTER, and 3) resume search
by pressing FS or SS. Also, you can
select the channel in which you wish
to make the entry (if you have not
beforehand) by switching back to the
SCANNER mode and manually advancing to the desired channel position. To
retur- to search: Press PROGRAM,
then ENTER, and resume by pressing
y
2)-e3,
is so
Lend a Hand, Boys
Readers all over the North American
Continent need help, and you may be
able to send them what they need. If you
have a schematic diagram that someone
needs, find out what it costs to "copy"
and write to the person stating the exact
cost. Shop around. Some copy machines
are 10 cents a copy and others are 25e.
Never send originals, cause Hank will
not be responsible for the mails. Help a
buddy (or gal) out and you may start
up a penpal friendship.
Maybe I should get in my request first.
I'm looking for an old radio, any make,
any type, that someone wants to part with.
Any reasonable condition is okay, 'cause I
want to enjoy restoring it. Just write to
me, Hank!
p Crosley Trirdyn 3R3, Type 121 regenerative receiver, needs hookup instructions: Tim Brannon, Rt. 6, Box 227, Gilmer, TX 75644. Tim also needs service
advice on Firestone Air Chief that is
motorboating.
p Knightkit R -55A receiver, need operator's manual and schematic diagram: Elmer R. Leonhardt, P.O. Box 655, Jamestown, TN 38556.
.
Let Kester Solder aid you in your home repairs or hobbies. For that household
radio, TV, model train, jewelry, appliances, minor
item that needs repairing
repair it yourself. Soldering
Save money
electrical repairs, plumbing, etc.
with Kester is a simple, inexpensive way to permanently join two metals.
use Kester Solder.
When you Solder go "First Class"
-a
-
-
For valuable soldering information send self-addressed stamped envelope to
Kester for a FREE Copy of "Soldering Simplified".
KESTER SOLDER
Litton 4201
WRIGHTWOOD AVENUE/CHICAGO, ILLINOIS
60639
CIRCLE 14 ON READER SERVICE COUPON
BIG
NEW!
COLOR TV!
BUILD YOUR
OWN
TV!
TY
SCREENle
Can be builttOOÁVEor
Special
No
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featured in November
Popular Science.
not included.
portable
Convert any
spare hours.
In a few
COIOr
TRON-EX F/1.9 LENS
u¡red.
electroPAICKAskGEORDERS!
LIFESCREEN III
The LIFESCREEN Ill projection system gives you all the enjoyment and excitement
of the $4000 systems. Our new injection molded Tron-Ex lens (F/1.9) produces
an amazing image that is over 3 times brighter than most nationally marketed
big -screen TVs-Including Sony. Md the Tren -Ex delivers sharper focus to the
screen edge for better overall clarity. Our light -enhancing Extron LS -50 screen is
brighter than most movie screens. because the molded parabolic contour
rejects extraneous light, concentrating a directionally selective TV image tor clear,
colorful viewing. The LIFESCREEN Ill plans provide exact dimensions to fit the
t3" Toshiba (model C389). but they can be modified to fit most 12" to 19"
portables. Pre -constructed LIFESCREEN Ill lens housings available for most
COMPLETE PACKAGE $319
TVs. Order the components catalog below.
6 times
LIFESCREEN II
LIFESCREEN
sell -contained protection system
that uses any transistor portable TV
requires only 2 x 4
(12" to 19")
feet of floor space
fits neatly against
any wall and lends its beauty to the decor
of any room, Includes Tron-Ex F/1.9
lens, Outrun LS-50 screen, two front
surface mirrors, and building plans for
The
The
.
...
the cabinet
I
original independent projection
system from Extron. Works with the
Sharp 13" model 13A29 color TV or
Sony 15" model KV1541R color TV.
Can be used with any size screen. The
LIFESCREEN includes our new Tron-Ex
F/1.9 lens, one front surface mirror.
building plans for cabinet, and the LS -50
screen, 32" x 40"/50" diagonal.
-
I
COMPLETE PACKAGE $369
COMPLETE PACKAGE $339
EVERYTHING: the professional quality, accuracy of
description and availability of components described in this ad. After building
your LIFESCREEN PROJECTION SYSTEM, It you are not satisfied for any reason.
EXTRON
GUARANTEES
return all
cm.
'
ants to EXTRON for instant refund.
LARGER SCREENS FOR THE LIFESCREEN
Please send me the items checked below.
ONE COMPLETE SET OF LIFESCREEN I PLANS
ONE COMPLETE SET OF LIFESCREEN II PLANS
ONE COMPLETE SET OF LIFESCREEN Ill PLANS
I
AND LIFESCREEN
111
aEXTRON LIFESCREEN PROJECTION SYSTEMS
FS or SS.
ELEMENTARY ELECTRONICS/July-August 1978
8833 Sunset Boulevard Suite 202
.. $9.00
West Hollywood, CA 90069
.. $9.00
S9.00
5339.00
COMPLETE LIFESCREEN I PACKAGE
5369.00
COMPLETE LIFESCREEN II PACKAGE
$319.00
CONFUTE LIFESCREEN Ill PACKAGE
EXTRON COMPONENTS CATALOG (Applicable toward any purchase) $1.00
All prides IF.0.8. factory-Cal. residents add 6% sales tax
TOTAL S
.
SYSTEMS CAN BE ORDERED FROM OUR CATALOG.
AndeKI
wee
Name
Address
Cloy
lip
State
CARD NAME
CARD NUMBER
EXP
DATE
SIGNATURE
CIRCLE 9 ON READER SERVICE COUPON
23
DX central
reporting
A
world of SWL info!
BY DON JENSEN
3
Help is only
a REACT
team away
Relax, you've got some friends you
haven't even met yet. Probably right in
your own home town. They're your
neighbors who've joined the local
REACT Team, part of an international
people -to -people organization dedicated to improving highway safety and
serving the community by maintaining
an emergency CB radio network.
Dedicated is the right word, too.
This year REACT members will
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hours monitoring CB Emergency Channel 9. They will receive accident reports,
help lost or stranded motorists; report
unsafe road conditions and accidents;
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with car problems; and cooperate with
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It's important volunteer work. And
today more than 200,000 active REACT
participants monitor CB Emergency
Channel 9 in all 50 United States, Canada
and Mexico. And REACT is growing
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And that's good news for every
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GETTING THOSE QSLs-or veries,
verifications, confirmations; they all
mean the same thing-is an art in itself.
Many times the DX listener will find
that it is tougher to coax a letter or
card in reply to their reception report
than it was to hear the station in the
first place.
A QSL, a verification is just that, a
reply from a station confirming that the
report of reception you sent to them
was correct and, in fact, that you did
hear them when and where you stated.
Theoretically, at least, a QSL is your
proof, to be kept on file or displayed
on your walls, that you received the
signals of Station X. In practice, the
value of a QSL as proof depends on the
vagaries of station policy, how carefully your report was checked for accuracy. But regardless, QSL collecting
can be fun.
Getting QSLs. Many of the large international broadcasters are ready, willing
and yes, sometimes even anxious to receive your reception reports and to
QSL them in return. These are the stations that deliberately direct their programs, usually in English, to North
American SW audiences. They do wish
to get feedback from that audience.
And so to encourage you to write, they
will offer colorful QSL cards, pennants
or other little gifties.
But there are many other stations in
the world of shortwave. These broadcasters program to home service audiences, local or regional listener. Often
their programs are not in English. They
are not deliberately seeking North
American audiences. So they don't alway respond promptly to listener requests for QSLs.
And, of course, no broadcaster is
under any obligation to send QSL cards
or letters to listeners who report reception of programs. Normally a station's
staff replies because they're interested in
building goodwill, or because a station
engineer is interested in knowing that
his signal is doing a good job and is
being heard across the world, or simply
as a courtesy.
So politeness, when you're writing
your reception report to a station, is a
must. You may ask for a QSL to confirm your report, but don't demand. It
won't get you anything you otherwise
would not have received. And enough
nasty letters to stations could adversely
affect their QSLing policies.
Perhaps the best way to report your
reception is to write a personal letter
to the station's manager, engineer or
English Language program department.
Your report should include certain
basic elements. These are the frequency
on which you heard the station, the
date and time of reception, the conditions of reception, a detailed listing of
the programming you heard and supplemental remarks. The latter could include information about your listening
equipment, about yourself and your interests, or your personal comments
about the programs you heard.
It is important to state the frequency
on which you heard the station. Some
stations use a number of different frequencies simultaneously, so if you
neglect this aspect, the station will have
no idea which particular transmission
you heard. Sometimes it is hard to understand a station's announcements and
sometimes listeners make mistakes.
They think they are hearing one station
when it is actually something else.
If the programming is in English, it
is usually fairly easy to determine the
frequency in kilohertz. Usually it will
be mentioned in the announcements. If
it is not announced, you must do the
best job you can in estimating the correct frequency. Some of the better receivers make it fairly easy to readout
the tuned frequency. Others fall down
badly on this score. All I can say is to
try to be as accurate as you can in
determining the frequency of the tuned
station.
DX Glossary
BBC -=-British Broadcasting Coropration
DX, DXing=Listenine to distant or
hard -to -hear stations as a hobby
DXer=One who DXes
EDT, CDT, MDT, PDT Eastern
(Central, Mountain, Pacific) Daylight Time
EST, CST, MST, PST=Eastern (Central, Mountain, Pacific) Standard
Time
GMT=Greenwich Mean Time
kHz=kilohertz, most commonly used
unit of frequency measurement; identical to kilocycles per second, which
is abbreviated, kc/s.
log=a list of stations
QSL=verification card or letter' from a
station, confirming as correct the DX er's report of reception
SW=shortwave
ELEMENTARY ELECTRONICS ,July -August 1978
Timing. When it comes to a time reference in your reception report, usually
the preferred approach is to use the 24 hour clock system and use Greenwich
Mean Time references.
The 24 -hour time system simply
eliminates any a.m. or p.m. designations. The hours from midnight to
noon are not much different from the
time reference system we're all familiar
with. One a.m. becomes 0100, 2 a.m.
is 0200 and one minute before noon is
designated 1159 hours. After noon,
however, the count keeps running. One
p.m. is 1300, 2 p.m. is 1400, up until a
minute before midnight, which is 2359
hours.
Greenwich Mean Time or GMT is a
standard time reference at the zero degree meridian that passes through
Greenwich, England. When dealing
with stations all over the world, each of
which has its own local time, it is much
easier and more convenient for everyone concerned to use a standard reference time called GMT.
It is equivalent to EDT + 4 hours,
EST or CDT + 5 hours, CST or MDT
+ 6 hours, MST or PDT + 7 hours,
PST + 8 hours. For instance, if it is
12 noon PDT in your California community it is 1900 GMT. And if you live
in Miami and the local time is 2:30
p.m. EDT, it is 1830 GMT (1430 + 4
hours) .
The important thing to nóte about
the date in your report involves the use
of GMT. Be sure to make the date correspond to GMT! Thus, it may be 10
p.m. EDT in Baltimore where you do
your DXing, and your calendar may
show it to be the evening of August 14,
but remember that the cIMT time equivalent is 0200 (that's 10 p.m. or 2200,
plus 4 hours), some 2 hours into the
new date of August 15. Your report
should read 0200 GMT, August 15.
Loud and Clear. You should report
also to the station how well you heard
their signal. Admittedly this is something of a formality with the large international broadcasters who get thousands of similar reports. They have a
pretty good idea already of how their
signals are being heard in North America. Still, even with these outlets, your
technical notes on signal strength, interference, static and atmospheric noise
and fading could be helpful, especially
if you've noted some new condition,
some transient problem with their transmitting operation of which they weren't
aware.
Without an accurate account of the
program you heard, a detailed list of
the broadcast items, the station really
has no way of determining if it was
really the one you heard. Include a
summary, but with enough detail so the
station's staff can check it against pro (Continued on page 92)
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A colorful era in communications
newscan
Electronics in the News!
Galactic Molecule Breaks
Four -Minute Mile
In the last two years research scientists at the National Research Council's
Herzberg Institute of Astrophysics
(Canada) have discovered three new
"heavy" molecules in deep space. Following the original discovery of the
molecule HC,N (cyanobutadiyne) with
a molecular weight of 75, NRC's radio
astronomers continued their investigations leading to the finding of HC7N in
the Spring of this year. HC7N has a
weight of 99 on the atomic scale. With
today's announcement that HC9N
(cyanooctatetrayne) has been confirmed as well, the molecular weight of
compounds in space has passed the 100
mark, reaching a level of 123 atomic
units. That's like breaking the old 4 minute mile barrier.
While the figure of 100 is of passing
significance in itself, the finding of this
heavy molecule has intensified speculation on how such large compounds
originate In space where simplicity is
the rule. Most molecules in space are
made up of a few small atoms and
rarely form any large complex structures. HC9N becomes a virtual monster
in contrast to previously found species.
More important than weight alone is
the now -increased awareness that since
molecules of such size exist in space,
somewhere in the dark, mysterious dust
clouds between the stars may be a real
amino acid-the basic building block of
history ended when RCA Global Communications, Inc., demolished the last
of 12 giant transmitter antenna towers
at Rocky Point, New York in December of 1977. The 410 -foot antenna was
all that remained of "Radio Central,"
the most powerful radio station in the
world in its heyday. The Rocky Point
facility was built in 1921 and was the
principal station that linked the United
States with the rest of the world. It was
the "hopping off" point for messages
transmitted by RCA to Europe, Central
and South America. Radio Central covered approximately 10 square miles,
an area roughly half as large as Manhattan Island.
The official opening of Radio Central
on November 5, 1921, was hailed as a
milestone in wireless progress. President
Harding, in the White House, threw a
switch that put Radio Central into
operation. Stations around the. globe
had been alerted to tune in for a congratulatory statement by the President.
"Long waves" were necessary for
long distance communications in those
days and the state of the art dictated
the use of high steel towers to support
massive antenna structures. There were
originally 12 towers, each 410 -feet high
and weighing 150 tons, that stretched
over a three-mile area on the eastern
end of Long Island. As communications technology developed, the long
wave system became obsolete. The
vacuum tube, which made possible short
wave transmissions, followed by improved cables and eventually satellites,
made the two giant Alexanderson alternators and antenna "farms" a thing
of the past. One of the 200 -kilowatt
alternators is now in the Smithsonian.
RCA demolished 11 of the towers
in the 1950's and early 1960's. The
life.
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This diagram shows the molecular structure of the latest find of NRC's radio
astronomy team at Algonquin Park. The
two small spheres represent one hydrogen
and one nitrogen atom linked by a chain
of nine carbon atoms, resulting in a molecular weight of 123. These atom form 3 of
the 4 components necessary to life as we
know it on earth. The whirling of the
molecule in space generates the radio:.
signals that the scientists detected.
Dynamite charges topple he last of the
giant 410-foot radio towers that was once
the most powerful station in history, Radio
Central. Communications satellites and
undersea cables made these towers obsolete remnants of a long -gone era of radio
communications and entertainment.
last one has been used most recently as
a support for aviation beacon lights and
radio antennas for higher frequencies.
ELEMENTARY ELECTRONICS/July-August 1978
5 GREAT
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BEGINNERS GUIDE TO MICROPROCESSORS
Everything you need to know to get started with micro- I
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51 PRACTICAL PROGRAMS AND GAMES IN BASIC
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>0'41
Photo shows the Rocky Point transmitting
station with its swimming-pool that provided cooling water for the transmitters.
Behind are a few of the 12, 410 -foot tall
long wave antenna towers.
by present elevator control
equipment, Bill Hoelscher, shows off his
new microprocessor commander.
Surrounded
But it's not even needed for that anymore, so RCA decided to demolish it.
It took two months to build the
tower; it stood for 56 years, but it was
demolished in a few seconds. As it
crashed down, the tower gave a booming farewell to a colorful era long past.
The Chips are Down on
Up Elevators
An electronic "sergeant" commanding a whole company of elevators. Bill
Hoelscher might not agree with that
rather high -blown description of a
microprocessor. But he concedes that's
what the electronic age has come to: a
pygmy computer with a fabulous memory telling up to eight elevators when
to go and where to stop.
Hoelscher, if you want to be more
formal, is William R. Hoelscher, chief
electronics engineer for U.S. Elevator
of Spring Valley, California. For more
than two years, he and his colleagues
have been working to shrink down to
suitcase-size the electronic control system required to command and operate
a bank of elevators. Now the Hoelscher
team has scored with a new generation
microprocessor to replace what only a
few years ago filled an entire average sized room with countless yards of
wiring, circuitry, vacuum tubes and
other electronic paraphernalia.
In layman's terms, the microprocessor memorizes the missions of its elevators and command them to do as
they're told. Yet this pygmy microprocessor can command up to eight elevator cars serving up to 48 landings
(that's floors to lay people). Since in
very tall buildings, not all cars stop at
all floors, the little "sergeant" could
control and command a fleet of eight
cars servicing a 100 -story building. This
is no Buck Rogers lash-up. The new
microprocessor system saves space,
parts, electrical power and therefore
countless dollars for the customer.
Moreover, its reliability is infinitely
greater than earlier states -of -the -art
made possible.
ELEMENTARY ELECTRONICS/July-August
A dramatic savings in costs will come
in another new generation development: the replacing of up to 100 individual wires with only two in the call
signals for each elevator car. Imagine
the savings in costs when you install
two wires instead of 100 in each car.
Because Hoelscher is an engineer he
is cautious. He concedes "we have to
learn to walk before we run" with the
microprocessor. Nevertheless, he envisions this combination of electronic'
"heart" and "brain" as the beginning
of a new era in elevator service for
either low or high-rise buildings.
New Light on Power Conservation
A new phosphor is credited with the
greatest single boost in fluorescent lamp
efficiency since the 1950's. The phosphor, which coats the inside of the new
General Electric Watt -Miser II lamp
combines a narrower band of blue light
from one phosphor with a brighter
yellow-emitting phosphor. The resulting
35 -watt lamp is capable of producing
97 percent as much light as standard
40 -watt fluorescent lamps and thus can
reduce lighting system energy costs by
as much as 14 percent. That's where
the energy saving is, and that's the news
story.
Translated into energy costs, this dramatic gain in lighting efficiency means
that an estimated $770 million could be
saved in the nation's electric bill each
year if the more than 800 million 40 watt fluorescent lamps now installed in
commercial
industrial plants
and
throughout the country were replaced
by the new GE reduced -wattage fluorescent lamp. This would be a significant
contribution to the U.S. energy -conser-
vation program.
Phosphors-the chemical compounds
that are coated on the inner surface of
a fluorescent tube-emit visible light
when exposed to the ultraviolet radia (Continued on, page 96)
1978
MICROPROGRAMMING FOR COMPUTER HOBBYISTS
A unique programming manual that takes you right
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MINIPROCESSORS: FROM CALCULATORS TO COMPUTERS
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Train with NTS for the
MicroComputers, digital
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The world of electronics is daily becoming more
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The equipment you receive with NTS training
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28
background in electronic systems. Kits and lessons
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Step-by-step, you learn how and why digital
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Whether you are looking for training in Consumer,
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ELEMENTARY ELECTRONICS/July-August 1978
electronics of the future.
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ELEMENTARY ELECTRONICS/July-August 1978
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Stability: Less than ±500 Hz drift for any 30
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10dB AM-belier than 2 uV for S/N
10dB (400 Hz 30% modulation)
t
Selectivity: SSB/CW ±.1.5 KHz (-6dB), 4 KHz (-50dB)
AM ±3 KHz (-6dB), t7 KHz (-50dB)
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Weight: approximately 7 kg.
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CIRCLE 8 ON READER SERVICE COUPON
32
ELEMENTARY ELECTRONICS,'July-August 1978
elementary
.
1978
'°1978
Electronics
Our phototachometer travels
in the best of circles!
by Walter Sikonowiz
you probably own
variety of motor -driven appliances and devices; autos, boats,
washing machines, lawn mowers, power
tools, model airplanes, movie projectors,
tape recorders, and so forth. Again like
most people, you probably never give a
thought to the proper maintenance of
these items until they break down. One
of the surest indications of an upcoming breakdown is improper motor
speed, and for about $35 you can make
a tachometer to measure it.
A good tachometer is an absolute
necessity for the proper maintenance
and tuning of motor -driven devices, and
we here present Mack the Tach, every
bit the equal of commercial units
costing around $200. Motor speed can
be measured on four ranges from 1000
RPM full-scale to 30,000 RPM fullscale. Accuracy is an excellent ±21h c"(
of full-scale on the 10,000 RPM range,
and ±31 2 r; of full-scale on all other
ranges. Furthermore, because this tachometer is optically coupled, no extra
load is placed on a rotating device while
it is being tested. The result is better
accuracy, especially with small, light duty motors.
Seeing the Light. As you probably
know, RPM measurements are just frequency measurements. In order to obtain an RPM reading on an analog
meter, we need a frequency -to -voltage
converter circuit. Such a circuit is detailed in the block diagram. Assume that
we have arranged things so that every
time the motor rotates, one pulse of
light falls on the photo -transistor. This
causes the photo -transistor, to conduct
and trigger the monostable circuit that
follows. Each time the monostable is
triggered, its output (point A) rises to
a high potential for a fixed time interval
LIKE MOST PEOPLE
a
ELEMENTARY ELECTRONICS/July-August
T, then drops low again, remaining low
until re -triggered. The monostable output next feeds into an averaging circuit,
whose output (point B) is ideally a
D.C. voltage that drives a meter.
Operation of Mack the Tach is explained more clearly by the voltage diagrams. At low RPM, the monostable's
output pulses are spaced fairly well
apart. Consequently, the average value
of the output is low, as indicated by the
D.C. level dashed -in on the diagram.
Since the average value is low, the meter
will only deflect a little bit. Now, at
higher RPM, the monostable gets triggered more frequently. The mono -
stable's output spends proportionately
more time at a high potential than at a
low potential. The average value of the
monostable's output is now higher, and
this results in a correspondingly higher
reading on the meter. In both the high and low -RPM cases, the monostable's
output rises to the same high potential
for the same time interval (T) ; higher
RPM decreases the time between pulses,
and this alone results in a higher average voltage at the monostable's output.
Let's next examine Mack's schematic
diagram. Diodes D2 and D3 full -wave
rectify the A.C. voltage from transformer Ti. This rectified current splits
WHEEL, OR OTHER ROTATING
DEVICE
ALUMINUM
FOIL
n
LIGHT SOURCE
LIGHT
SOURCE
PROPELLOR, OR ANY
DEVICE CAPABLE OF
CHOPPING A LIGHT BEAM.
Mack the Tach may be used to measure the rotational speed of just about any object that
can "chop" a light beam simply by using it as shown in the lower right. If you wish to
measure rotational speed of something such as a wheel then use the aluminum foil as
shown, reflecting light off it into Mach's home -built, light-sensitive probe.
1978
33
el@MACK THE
TACH
two ways: to DI and to R3. Consider
first the path through R3, D4, C4, and
R2. The purpose of this four -component network is to provide a 120 Hz.,
clipped, full -wave -rectified sine wave,
available whenever S2 is fully clockwise. This signal is used to trigger
monostable IC1 during calibration.
Now let's consider the alternative
path of the rectified current through DI
to Cl and IC2. Cl smoothes out the
rectified A.C., while DI isolates the
R3 -C4 -D4 -R2
network
from
the
smoothing action of Cl. Voltage regulator IC2 transforms the unregulated
D.C. voltage across Cl into a. regulated
5 -volt potential at its output (pin 3).
Capacitors C2 and C3 bypass the 5 -volt
supply and stabilize the circuit.
Transistor Q1 is the photo -transistor,
and it connects to the rest of the circuit
through a piece of coaxial cable terminated in P1. Plug P1 connects to jack Jl
So long as Range Selector S2 is not
in the Cal. position (extreme clockwise), the trigger input (pin 5) of IC]
8
4
-
Above is a foil -side pattern for making your own Mack the Tach PC board. As you can see,
this circuit is simple enough to allow use of a resist pen to make the board if you do
not have photographic means at your dispos41. Beneath is a component -side view of old
Mack. Make the board, plug in and solder the components and what a spin you'll he in
EMITTER
OI
COLLECTOR
TO S2b
.
will be connected to photo -transistor
Q1's collector through S2a.
Changes in the intensity, of the light
incident on Q1 produce changes in Q1's
collector potential, thus triggering ICI.
The' duration of the output pulse available from monostable IC1 is controlled
by C6 together with either R4, R5, R6,
or R7. Switch S2b selects the, resistor
appropriate to the RPM range in use.
ICI's output (pin 6) drives transistor
Q2, which then drives meter MI
through R8 and R9. Q2 provides some
current gain, and it also ensures that all
current to the meter gets cut off when
pin 6 drops to its low level (a few,
tenths of a volt).
The averaging
in
this
circuit is performed to some extent by
meter M itself because the inertia of
the meter's needle causes the deflection
to be proportional to the average cur:
rent.
At low RPM, however, the meter
needle would vibrate perceptibly, so
capacitor C5 assists in averaging the
pulses. Even so, you may still notice a
little vibration when reading very low
RPM; this is normal and not a cause
for concern.
Light and Easy. Construction of the
tachometer is particularly simple.
Though a printed circuit board is optional, it does make construction even
easier-transformer T I is especially
made for PC mounting. Instead of the
usual solder lugs, this transformer's
lead wires are brought out as pins,
I
34
TI
117
S2a
S2a
MI(-)
MI(+)
(ROTOR)
which then are soldered directly to the
circuit board. The Signal Transformer
Co. will supply you with one of these
units for just $4.90 plus postage. See
the parts list for their address. Incidentally, while you're ordering the transformer, be sure to request a copy of
their catalog. It contains a tremendous
variety of reasonably priced' and often
hard -to -get transformers.
Parts layout within our Mack the
'Tach is not critical, so you may use any
convenient arrangement. The photographs which accompany this article
show how the prototype was built into
a 6 x 5 x 21/2 -inch plastic cabinet. As
you can see, there was room to spare.
When drilling your cabinet, provide an
access hole for R9 as this will allow you
to calibrate the circuit without removing
the front cover every time.
Meter M1 is a 0-100 microamp D.C.
unit, and while any similar meter will
the Mouser #39LK417 is both
accurate and reasonably priced ($10.95
plus $3.00 handling). You'll find Mouser's address in the parts list. Incidentally, if you happen to have a 0-100
microamp meter at hand, you can use
it, but remember that the accuracy of
the meter will determine the overall
accuracy of your tachometer.
A few further comments on some of
the other components are in order. Note
that resistor R3 should be a 150 -ohm,
-watt unit. If you don't have a 1 -watt
resistor, two 330 -ohm, 1/2 -watt resistors
in parallel can be used instead. Almost
any phototransistor can be used for Ql.
Fairchild FPT-110s and FPT-100s
(Radio Shack #276-130) were used
with success. As noted in the parts list,
resistors R4, R5, R6, and R7 were 1%
units in the prototype. You can get by
with 5% units which will leave the accuracy at about ±21/2 % of full-scale on
do,
1
ELEMENTARY ELECTRONICS/July-August 1978
o
LOW RPM
+5
I
--TH
VOLTAGE
TIME
HIGH
At low RPMs, the voltage pulses from the
monostable output are
far apart in time and
this lowers the average
voltage level. As the
RPMs increase, these
pulses become closer
and the voltage rises as
read on the meter.
RPM
1+5
VOLTAGE
TIME
to get the proper orientation when installing it intò the circuit. The same caution applies to all the semiconductors,
meter Ml, and capacitors Cl, C2, and
C5. As an added precaution, use a
socket for IC1. In this way the IC can
easily be removed if by chance it should
the 10,000 RPM range; however, accuracy on all other ranges will now be less
than or equal to ±71/2 % of full-scale.
Timing capacitor C6 is a 1.0-uF
electrolytic, but be sure to use a tantalum device, not an aluminum capacitor.
With this capacitor you must be sure
Why spend anywhere from one to two hundred dollars for a tachometer when you can
build our Mack the Tach? He's quite functional, and will only set you back about $35
to get it all together. Optically coupled,
his design will assure great accuracy.
R4 -30.1K,1',6
R5- I0K, 1%
R6- 3010,1%
_R7 -1000,1%
TI
IC2
7805
S2B
RI
DI
D2
N
N
20
5
6
o
4700
J1
,
Q2 2N
1,0u F
S2A
14
10
5
ICI
3904
I
I
.IuF
IIM
150
D4
IN748i
I
Find
them
4
R8
5600
CI
1000uF
C2
R9
10k
ti
100uF
123
C4
u F
.1
vsis
parts?
8
74121
N. C.
R2
D3
C3
6
I
12891215 347
. 1J
Need
1
e
2
I
VCT, .12A
in
R3
150,1W.
HQBEY
QI
MART-page 83.
FPT-100
PARTS LIST FOR MACK THE TACH
C1-1000 uF, 25V electrolytic capacitor
C2-100 uF, 16V. electrolytic capacitor
C3, C4-.1 uF ceramic capacitor
C5-470 uF, 35V. electrolytic capacitor
C6-1.0
D1, D2,
uF, 35V.
tantalum capacitor
03-1A., 200
D4-1N748A, 3.9 volt,
F1-1/4 amp. fuse
PIV
1/2
rectifiers
watt zener diode
M1-0-100 microamp.
Q2 -2N3904
ALL RESISTORS
FIED OTHERWISE
R1
1/2 -WATT,
-4700 -ohm
R2 -150 -ohm
R3 -150 -ohm,
11-phono jack
R6 -3010 -ohm,
Watt
1%
R5 -10,000 -ohm,
1%
1%
R7 -1000 -ohm, 1%
ELEMENTARY ELECTRONICS/July-August 1978
10%,
UNLESS
SPECI-
R8 -5600 -ohm
-10K trimmer pot
St-SPST slide switch
R9
S2-DP5pos. rotary switch
T1-20
VCT, 120 mA., PC -mount
transformer
#ST -3-20; $4.90)
misc.-fuseholder, pen barrel, plastic case,
(Signal
line cord, knob, coax
1
R4 -30.1K,
-phono plug
21/2% panel meter
(Mouser ##39LK417)
Q1-Fairchild FPT-100 photo transistor
ICI-type 74121 TTL monostable vibrator
lC2-type 78055V. voltage regulator
P1
D.C.,
IC
socket.
obtain the special parts at the following places. Mouser Electronics, 11511
Woodside Ave., Lakeside, Calif, 92040 and
You may
Signal Transformer Co.,
Inwood, N.Y. 11696.
500 Bayview Ave.,
35
MACK THE TACH
10K
3000
RPM
RPM
30K
RPM
1000
RPM
CAL. (72)
RANGE SELECTOR
S2
Design your front panel as this diagram
shows. The RPM full-scale readings can be
calculated using the table of RPM Full
Scale vs. Mult. Factor, given in the article.
turn out to be defective. Finally, note
that voltage regulator IC2 is simply
soldered to the circuit board. No heat sinking of this IC is required because
only a small amount of supply current
is consumed by the circuit.
In order to protect Ql, a photo -probe
assembly will have to be constructed,
which we have illustrated. Start by
threading one end of a small -diameter
coaxial cable (Belden 8417 or the
equivalent) completely through the
plastic barrel from an old pen. Now,
grasp photo -transistor QI, and cut its
base lead completely off. Solder the
central conductor of the coax cable to
Q1's collector, and then solder the co ax's shilde to Q1's emitter. Pull on the
coax so as to retract Q1 far enough
into the pen barrel so that its light-sensitive face is recessed one-half inch.
Carefully secure Q1 and the coax to the
pen barrel using epoxy cement. Finish
up by attaching plugP1 to the far end
of the coaxial cable.
Once you've completed construction
of Mack, only calibration remains. Adjust R9 so that its resistance is maximum. Turn on the power, and put S2
into its Cal. position. Now adjust R9
for a reading of exactly 72 on Ml. This
completes the calibration. In the future
you may re -check the calibration simply
by repeating the above procedure. For
most applications Mack the Tach as
originally designed has adequate sensitivity. In fact, it is desirable for a photo -tachometer to have a minimum practical amount of sensitivity; in this way,
ambient lighting conditions rarely affect
a measurement. If added sensitivity is
desired, however, the easiest course (besides going to a more powerful light
source) is to replace Q1 with a photo Darlington transistor, which must be
36
Construction can be made roomy, as it was here in the author's model. One thing the
photo does not show is the access hole for R9. It's a good idea to drill one; it can save
you all sorts of time whenever you want to recalibrate the circuit. Meter M1 is a 0-100
u -Amp DC unit. We used a Mouser #39LK417 and you will find that company's address
and other information in the parts list. Any good phototransistor can be used to give
Mack the eye. You'll find that construction will be straightforward and fun too!
When a light pulse falls
on the phototransistor,
the transistor conducts
and triggers the mono stable circuit which
follows. When triggered, this circuit's output
goes high, then returns
low. The output is fed
into an averaging circuit and the meter.
+5
MO NOSTABLE
ti
PERIOD =T
Q
AVERAGING
CIRCUIT
o
ti
ti
1
PHOTOTRANSISTOR
METER
LIGHT
PULSES
NPN. One good choice is a type
2N5777. available from Poly-Paks as
stock number 92CU2649. Other types
may he used as well. Hookup is identical to that of a standard photo -transistor.
Let's now discuss the use of the tach.
To begin with, you should place range
switch S2 so that full-scale deflection is
well above the motor's estimated RPM
After the first reading, drop down to a
lower range if necessary. You'll notice
in the photos of the prototype that
meter MI's scale was left with its original markings: 0 to 100. It's then easy
to apply a multiplication factor appropriate to the given range, as shown
below.
RPM
FULL SCALE
1000
3000
10,000
30,000
MULT.
FACTOR
X10
X30
X100
X300
When setting up a measurement, it is
important that the ratio of maximum to
minimum illumination of Q1 be as high
Not only is the pen mightier than the sword
but an old pen barrel can show you the
light! Build Mack's unique, light-sensitive
probe-a pen to house the phototransistor.
possible. So far as the maximum illumination is concerned, a 100 -watt bulb
can saturate (fully turn on) Q1 from as
far away as 5 feet, approximately. This
assumes that the bulb is in a suitable
reflector. If not, Q1 will have to be
nearer to the lamp (about a foot away).
The minimum light intensity on Q1
should be as low as possible. Recessing
the photo -transistor helps in this respect, since stray illumination is thus
eliminated Try to avoid fluorescent
lights as sources of illumination for
your Mack the Tach; incandescent bulbs
(Continued on page 96)
as
ELEMENTARY ELECTRONICS/July-August 1978
ele assembles the...
SABTRONICS 2000
DIGITAL
MULTIMETER
CIRCLE 52 ON READER SERVICE COUPON
Easy -to -read digits and professional
performance in
low-priced kit.
a
mizing of functions that allows Sabtronics to deliver so much for so little
cost.
Since there are four full L.E.D. devices, rather than three, plus a device
with a "carry one" and "+", the DMM
provides full 100% overranging. This
means that if you have set the meter
for, say, 10 volts, it will read to 19.99
volts (a full four digit readout). Similarly, if the meter is set for the 100
VAC range it can indicate as high as
199.9 VAC. When the overrange capacity is exceeded the display blanks
out to indicate you have really exceeded the capacity of the meter. Only
the decimal point, and negative ("-")
indicator-where applicable-stay lit to
tell you the meter is really on and that
you have exceeded the overrange.
The DMM measures AC and DC
volts, ohms, and AC and DC current,
with all functions and ranges selected
by pushbutton switches. A somewhat
unusual arrangement is provided for the
range switches. Three switches provide
SO quickly you can find an under -$100 digitae multimeter in most electronic parts
stores-, problem is, however, these are
generally "pocket" meters with ittybitty readi uts. When you want a "full
size" digital readout and battery power
you're generally talking "big bucks,"
a cost in excess of $100.
Now for the gond news: If you can
put in a long evena1g of assembly, and
have had a moderate degree of experience building "solid state" kits,
you can have a full size, battery -powered digital multimeter for well under
a C -note. The Sabt onics Model 2000
DMM is a digital .tultimeter kit that
will only set you b, ck $69.95!
The Model 2000 DMM's four digit
readout is provided by 0.3" L.E.D.s.
Through a rather novel use of the most
significant digit (the left one), a "minus" is provided by the center segment
of the left digit, thereby providing
five symbols though only four L.E.D.
devices are used. It is this sort of maxi -
TbCHNOLOGY HAS ADVANCED
FUNCTION
-
eabtrontcs v
lp¢m'tY.V
'
vSti
4iP
n-4f
RALLE
T±A
tma
tOCwA
tMSD
1pM4
m"3,'
.1H
Does this readout say
MINUS 754 -ohms?!
Yes, it does and for a
very good reason. The
negative sign is always
indicated in the ohms
mode as a reminder
that the test voltage
used for ohms measurements is negative at
the positive test lead
jack (red). This is a
thing you would wish
to remember when
testing solid state
devices with the
ohmmeter!
ELEMENTARY ELECTRONICS/July-August 1978
_.
basic voltage ranges of 100 mV, 10 V,
and 1 kV; 10 uA, and 100 mA; 100
ohms, 10k ohms, and 1 Megohm. A
fourth switch labled "X10" raises the
full scale capacity of each range switch
by a factor of 10. As example, if the
10 volts switch is pressed, also pressing the X10 switch provided for a
range of 100 volts. Similarly, if the
range is set for 10k ohms, pressing
the 10 switch provides a range of
100k ohms. The position of the readout's decimal point is always correct
for both the direct range and with the
X10 selector switch.
Only two inputjacks are provided
for all functions, with the meter automatically displaying the correct polarity: it's positive when there is no polarity indication; negative when the "-"
is displayed. The "-" is displayed for
all ohms ranges, serving as a reminder
that the voltage at the positive (red)
test lead banana -type jack is negative,
a fact you must know if you use the
resistance ranges for checking solidstate devices.
The meter is protected for an input
voltage up to 1 kV, so there is no
overranging on the 1 kV voltage range
-1 kV is the highest voltage reading.
The frequency response of the AC
voltage ranges are within 1% from
40 to 20 kHz up to 10 volts (actually
19.99 volts), to 2k Hz on the 100 volt
range, and 500 Hz on the 1 kV range;
so you can use the meter for accurate
audio measurements up to 19.99 volts.
Current measurements can be made to
2 amperes, with the meter protected
by an internal fast -acting 2 ampere
fuse.
37
SABTRONICS MULTIMETER
INPUT AND GROUND JACKS
SWITCH ASSEMBLY
1@/@@
The worse -case accuracies for the
various functions are ±0.5%± digits
DC volts; 1% ±2 digits AC volts and
DC current; 0.8%±2 digits AC current.
The power supply requirements are
4 to 6.5 VDC at 120 mA nominal. As
supplied the meter works off four C cells, with Alkaline cells nominally providing 25 hours operation, while ordinary flashlight -type carbon-zinc batteries provide about 8 hours operation.
Optional accessories include Sub -C Ni cad and AA Nicad battery packs, a
recharger, an AC adaptor, and a "dropping" (regulated) supply for powering
the meter off 12 VDC (car battery).
The kit is supplied with a special set
of calibrating resistors.
The DMM is housed in a plastic
cabinet providing complete insulationno part of the cabinet is connected to
the test circuit or the meter itself.
Overall dimensions of the cabinet are
8 -in. wide x 27/s -in. high x 61 -in. deep.
A collapsible tilt bracket raises the
front 11/2 -inches.
Building the kit. This is not a kit
for someone with experience only in
Heathkits, or kits similiarly supplied
with detailed step-by-step instructions.
Though all components are designated
directly on the printed circuit board(s),
and there is an excellent pictorial, the
builder has to locate the exact position.
The manual says something similar to
"Install R1, R2, R3, etc.", it doesn't
tell you on what part of the board the
resistors are located; you must search
out the location yourself. Also, there
have been many changes since the assembly manual was printed, not all of
which are in the addenda sheets. For
example, the switch assemblies originally required extensive preparation
by the builder; in our kit the assembly
was factory-prepared for direct installation, but there was no mention of
this in the addenda sheets, and it took
some time to figure it all out.
To the kit's credit they do recommend using sockets for the ICs though
they are not provided (Radio Shack
has the required sockets). Save yourself heartache if you make a wiring
error, use the sockets even though they
do add a few extra dollars to the total
cost.
One very nice feature, which makes
up for the problems with the assembly
instructions, is that all test resistors and
test points plug into sockets on the PC
board. You don't have to open wiring
(Continued on page 88)
38
BATTERY HOLDER
COVER
The Sabtronics 2000 Digital Multimeter is housed in an attractive cabinet which ;is 'ati,ulated
from both the test circuit and the meter's electronic innards. Assembly should take an
experienced kit builder an evening or two-but you really should have a few other,
complex kits under your belt before tackling this one. For a state-of-the-art instrument, the
2000 goes together very easily if you know the basics. The kit is supplied with pictorials
in the manual and both schematic and component views of the PC board. If you want a
full-size meter with a digital readout and you'd like to keep the cost down, better
check the 2000. Circle No. 52 on the Reader's Service Coupon for information.
OP AMPS
A
/D CONVERTER
DIGIT
DRIVER
SEGMENT
DRIVER
SWITCH ASSEMBLY
LED READOUT
ASSEMBLY
Everything except the LEDs used in the readout is mounted on one printed circuit board.
The entire switch assembly is provided as a single unit and there is no interconnecting
wiring; instead, a single printed circuit board placed over the switch assembly provides
all interconnections and thereby sharply reduces the possibility of a wiring error.
ELEMENTARY ELECTRONICS/July-August 1978
SIGNAL
CHASER
Trap that circuit trouble and
chase those blues away!
by Martin Weinstein
WB8LBV
of troubleshooting is to start at those circuit
areas where there is no trouble,
then to back your way through the circuit until you've reached the point
where it isn't working. The same trick
can work frontwards, letting you trace
a signal through a circuit until you
reach the point where it disappears.
Here's a handy aid for troubleshooting in the frontwards fashion, a signal
tracer with a great deal of input sensitivity called Signal Chaser.
Built-in Demodulator. An ordinary
amplifier could help you find signals in
the AF (audio frequency) range, but
the Signal Chaser can do more. D1, a
N9l 4 diode, acts as a demodulator,
much like the diode in a simple crystal set -style radio, to demodulate AM (amplitude modulated), RF and IFsignals
directly to audio (or whatever the carrier is modulated with). On FM and
PM (frequency modulated and phase
modulated) signals, the diode acts as
a slope detector, giving a suitable, if
low -fidelity, audio output.
High Impedance Input. The one feature of this circuit that really makes it
shine when compared to most signal
tracers is its high impedance input. The
input impedance of the Signal Chaser
is close to 10-Megohms. This is due to
the use of a JFET (Junction Field
Effect Transistor) for Ql. Ql, a Siliconix 2N5458 or similar P -channel
JFET, is configured as a high -to -low
impedance converter with an input impedance determined mostly by the
value of R2, 10-Megohms. Capacitor
Cl blacks DC but passes AF, RF and
IF signals. Resistor R1 limits the input
current to Ql.
A high input impedance means that
for a given signal voltage, very little
ONE OF THE
SECRETS
current is drawn by the Signal Chaser.
This means that under almost all conditions, the Signal Chaser cannot load
down the circuit you are troubleshooting.
Speaker Size Output. The output of
Ql alone would be enough to drive a
high impedance earphone, but keeping
one in your ear while busy probing a
suspect circuit can be, to say the least,
inconvenient.
Instead, the output of Q1 (after demodulation) is coupled to the input of
ICI, an LM38ON audio amplifier. IC1
provides enough drive to power even
low -impedance speakers, around 8 ohms, to a good, healthy volume.
Capacitor C5 provides DC decoupling between the speaker and the output
of IC1.
Breadboard -Easy Consruction. The
entire circuit can be built up on a small
solderless breadboard like the one
shown (a Continental Specialties CorSocket,"
poration "Experimentor
model EXP350, about $5.50) almost in
less time than it takes to tell about it.
I've used three tricks here I would
especially like to share. For one, I
used a pair of zig-zag mounting brack-
1
ICI
R4
DI
C4
R2
R3
SPEAKER
G3
BI
SI
C5
C2
RI
(SWITCH CONCEALS)
CI
INPUT PROBE
GROUND
CLIP
Our Signal Chaser was built using a solderless breadboard and, as you can see, it made
for a neat component arrangement. If you follow this photo, be certain you don't forget
about R1, which connects to the Gate of Q1 and to Cl-it's really there, it's just hard to
make out in the picture! Signal Chaser should go together quite quickly, so if you start it
after lunch you should be chasing your first signals before the dinner bell.
ELEMENTARY ELECTRONICS/July-August 1978
39
I»
SIGNAL CHASER
Signal Chaser has
a
high impedance input
that is close to 10Megohms. It will draw
very little current and
so will not usually
load down the circuit
under test.
ets (from the local Radio Shack) as
battery hold-down clips. The mounting
holes in the CSC EXP350 helped make
this especially easy. At the far side of
the breadboard, the mounting holes
there happened to match exactly the
holes on a small speaker I had on
hand, and I was quick to take advantage of it. My third trick was to
solder stiff wire (resistor leads I cut
off some of the resistors in the circuit)
to the breadboard end of the shielded
probe cable. You may also want to
use "headers," available from several
sources and many parts stores for under a dollar a strip.
The rest of the assembly is fairly
straightforward. Follow the lead of my
layout, as shown in the photograph,
when you lay out your own Signal
Chaser-whether on solderless breadboard, a PC board or whatever method you use.
Understanding Solderless Breadboards. In case you haven't tried solder less breadboards before, you may not
know how easy they are to work with.
The holes in the face of the breadboard are arranged on .1" centers
(1/10th of an inch apart), which happens to be the lead spacing on standard DIP (dual inline package) integrated circuits and most other modern
components.
The center channel (.3" wide) is just
right for IC's to straddle. On each side
of the center channel are groups of
five holes (columns, if you view the
breadboard as widest on the horizontal,
with the center channel running left
to right). Behind each group of five
holes is a spring clip with slits between the hole positions to allow a lead
inserted into any one hole to be grasped
firmly and independently, and interconnected with anything grasped at any
other position in the group.
Each five -position terminal can be
interconnected with any other by simply using hookup -wire jumpers.
The separate rows (at the top and
bottom) are connected across their entire lengths and can be used for power
or signal busses. I use them to carry
the battery plus and minus lines.
Using the Signal Chaser. For most
run-of-the-mill signal tracing, clip the
probe cable shield to a circuit ground
near the area you're testing and touch
the probe to each side of the signal
C5
BI
-i
s
1
200NF
I
/T7
SPKR
1
(NC)
9V
C2
.INF
14
(NC)
13
II
12
path near each active or passive device
in the signal path. Start at the front
end and work your way to the output,
if you like-but skipping a few stages
on the chance they'll work can also
help you localize a problem.
The high impedance of the Signal
Chaser input means high sensitivity,
which lends it to some useful applications.
You can attach a coil of wire or a
magnetic tape head to the input to
inductively probe circuits and devices.
You can "listen" to the magnetic stripe
on the back of your credit cards, amplify a telephone conversation or pick
off the signal on your transmitter's
modulation transformer.
Or attach a photocell to the input
and listen to the sounds of light bulbs,
LED readouts, the sun, street lights
and then some.
Signal Chaser-not only a good introduction to solderless breadboarding,
but once it's built you may find it to
be one of the handiest gadgets in your
electronic bag of tricks -of-the -trade.
Have fun and chase those signals-and
those problems-down!
9
10
ICI
2N5458
C3
01
Cl
PROBE
2
4
3
5
6
.INF
R3
2000
/'n
=C
777
Z=400 R
ZINC IOM
m
50NF-r
m
R4
390
rr
fi
Find them
MART-page 83.
Need
parts?
m
in
HOBBY
PARTS LIST FOR SIGNAL CHASER
B1-9-VDC battery
Cl -.33-uF capacitor
C2-.1-uF capacitor
C3-1-uF capacitor
C4-50-uF capacitor
C5-200-uF capacitor
D1 -1N914 diode
IC1-LM380N audio amplifier
Q1
-2N5458
sistor)
40
JFET
(Juntion Field Effect Tran-
-100,000 -ohm resistor, 1/4 -watt
R2-10-Megohm resistor, 1/4 -watt
R3 -2000 -ohm resistor, 1/4 -watt
R4 -390 -ohm resistor, 1/4 -watt
S1-SPST switch
SPKR-8-10-ohm speaker
MISC-Breadboard (Continental Specialties
model EXP350 or similar) or other method
such as PC board; probe; insulated clip;
battery holder/clip; wire; etc.
R1
Solderless breadboard materials is arranged
with the holes about 1/10 inch apart. As
you can see, this just fits the spacing of the
IC's leads and of most modern components.
ELEMENTARY ELECTRONICS/July-August 1978
e/e assembles the...
Pennywhistle
103 Originate Modem
Keep in touch with
in personal computing, meet other computer hobbyists, and join local
computer clubs, it's more than likely
you'll find there's at least one timeshare computer system you can use
free, or at a very low cost. It might be
the local school's system which is available to students, or perhaps a friend
will let you in on his I.D. (identification
code), or it might be an older timeshare system now underutilized which
permits or even encourages outside
users for a nominal charge representing
the cost of upkeep or repair.
The advantage of .a time-share system, in comparison to the average personal computer, is that the time-share
generally will have several languages
in addition to BASIC: usually Fortran
IV and some degree of COBOL. It will
also have a file system, and a lot more
storage than the average computer hobbyist can afford to build into a home
system.
As a general rule, once you locate a
time-share you can get on, all you'll
need is an acoustic modem and your
present terminal. You connect your terminal to the modem, dial the telephone
number of the time-share system on
your regular phone, place the telephone
handset in the modem, and you're online to the time-share system.
Though most modems are relatively
expensive, you can go the kit route and
come up with a full -feature model one
half to one quarter the price of a commercial modem.
The way to go is with a Pennywhistle
(Originate
103 Originate Modem.
means it's used at the terminal. An
answer modern is used at the comS
YOU GET MORE INVOLVED
a
CIRCLE 64 ON READER SERVICE COUPON
time-share computer via your home telephone.
by the "surplus" dealers as RS -232 con-
nectors. Depending on the user selected
terminals the connections can be arranged for a TTY (teletype) current
loop or RS -232 electrical signal. The
TTY loop is through a non -polarized
optoisolater so even a hobbyist with no
knowledge of how a TTY works, or its
connections, can connect to the modem
with no hassle. Even the TTY current
source is provided by the Pennywhistle,
so you don't have to dig through the
guts of your TTY to find the current
source.
If you have a CRT terminal you will
use the RS -232 output. Since the Penny whistle can handle a Baud rate of 300
(30 characters per second) you might
as well use this rate in preference to a
lower Baud rate. (There are some hobbyists who run a CRT terminal with
RS-232 output at a TTY Baud rate of
110-only Heaven knows why.)
A set of LEDs flicker back and forth
when data flows through the modem.
Now for the extras. To start with,
three jacks are provided which can be
used to connect the modem directly to
a telephone line coupler, or to record
or play signals from the modem. You
puter.)
In addition to serving as a standard
modem, a means of coupling a terminal to a voice -grade telephone circuit,
the Pennywhistle has a few extra features that make it particularly attractive
for the hobbyist.
Connection is made through a 25
pin D -connector, the type often listed
ELEMENTARY ELECTRONICS/July-August 1978
can record data produced by the local
terminal and data received through the
line; you may also play back to the
local terminal and to the line.
Another extra is the low/high band
switch. Normally, an originate modem
transmits on the low band (1070 to
1270 Hz) and receives on the high
band (2025 to 2225 Hz). The answer
modem at the computer works on the
reverse, transmitting on the high band
and receiving on the low band. Long
distance telephone circuits now have
what is known as "echo suppressors"
which stop your voice from coming
back to you. If you're connected to a
time-share through a telephone system
with an echo suppressor your terminal's
printer is not going to get a signal back
from the computer when the terminal
is set for full duplex (meaning, the
printer gets the echo from the com-
puter.)
But with the Pennywhistle 103 you
can turn off the echo suppressor by
simply flipping the low/high switch to
high for a few seconds before transmitting data. The modem's output
switches to the high band and transmits a signal in the 2025-2225 Hz
The completed assem-
bly just before closing
the cabinet. The PC
board mounts in the
base. The muffs, acoustically insulated telephone holders, mount
on the top section.
41
PENNYWHISTLE MODEM
LEDS
RS232 CONNECTOR
1.
range. The telephone circuit is fooled
into believing it "hears" an answer
modem from a computer and turns off
the echo suppressor. You then flip the
switch back to low and use the modem
in a normal manner, getting full duplex
operation.
The low/high switch can also be used
as a send switch enabling two terminals
to "talk" to each other, though it's to
be doubted whether the function would
be used by the average computer hobby-
OPTO -ISOLATOR
_.
ist.
Building The Kit. This is not a "be-
ginner's" kit, simply because assembly
instructions are sparse. You get a parts
list, a stuffing pictorial (showing where
parts are located on the PC board),
and a minimal set of assembly instructions. If you need one -step -at -a -time
instructions with a pictorial for every
unusual step this is not the kit for you.
One outstanding feature of assembly,
which would be welcome in all other
kits from all manufacturers, is a direct
numbering relationship as to component placement on the PC board. Resistor R1 comes first, then R2, then R3,
then R4, etc. (If you're looking where
to put R23 it will be between R22 and
R24. Same bit with the other components such as diodes and capacitors.) In
other words, component identification
is in the correct order for the PC board,
not the schematic. It actually cuts about
75c' off PC board assembly time, and
makes it a snap to locate a value swap,
such as a 10K resistor for a 100K type.
Aligning Your Pennywhistle. Alignment requires a frequency counter and
a sine wave signal generator capable of
performance to at least 300 Hz. There
is no way to get around use of these
instruments; without them the Penny whistle 103 cannot work. Most of the
alignment consists of a few control
adjustments to get the correct counter
reading at a few test points. The procedure doesn't take more than five or
ten minutes. The only other main adjustment is to set the output level to
the telephone line.
Performance. The Pennywhistle 103
delivers the same performance as our
commercial modems-it works. We did
find the sensitivity was somewhat high
and tended to respond to noises within
the room. An engineering note supplied
in the instruction manual shows how
to lower sensitivity of the carrier detector by changing the value of two resistors. It was an easy enough modification even after the unit was completed,
and we suggest it be made if room
42
PHASE -LOCKED
LOOP
INDICATOR
DRIVER
CARRIER
OSCILLATOR
DETECTOR
Virtually the entire assembly is on one PC board. Because of a component order that is
in sequence for the PC board rather than the schematic this turned out to be the easiest
board to assemble we have ever assembled, and the simplest to debug (swapped resistor
values were quickly found). Note the input/output D -connector is part of the top edge
of the PC board, saving much trouble. Circle number 64 on the Reader Service Coupon.
To the right of the three control switches
are two LED lamps labeled CXR and ON.
These are the data indicators, which flick
back and forth when data passes through
the modem. If one locks On then there
is no data at all passing through the modem.
noises produce false turn -on of the
carrier.
We were able to make recordings of
the data signals, and while we have no
need for them, nor can see any reason
for making recordings of the data signals, nevertheless, the system is there
for your use if you have some particular need for the data recordings.
Summing Up. The Pennywhistle 103
works as it should, it's a lot of fun to
Using the modem is simple. You simply dial
up the computer, wait until you hear a
tone in the handset recever and then force
the handset into the muffs. Make certain
the handset is firmly seated in the muffs
to keep out any extraneous roqm noises.
build (for an experienced builder) and
is the least expensive way to modify
your personal computer equipment for
use on a time-share system. If you have
access to a time-share it's time you went
for a Pennywhistle.
The Pennywhistle 103 sells for
$129.95 in kit form from M&R Enterprises, Box 61011, Sunnyvale, CA
94088. Circle number 64 on the Reader
Service Card for more information.
ELEMENTARY ELECTRONICS/July-August 1978
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by the Editors of
ELEMENTARY ELECTRONICS
Answers to some of the most asked questions about personal computers
E T'S BEEN LESS THAN A year since we
r. heard the first rumors that both
Heathkit and Radio Shack were
working on personal computers for the
electronic hobbyist, yet in the few short
months since the rumors were proved
correct personal computing has become
the hottest thing going for the electronic
hobbyist and experimenter.
It has also become the most confusing, with each manufacturer and distributor inventing new terminology to
prove, or imply, his computer, system,
or accessory is the best. Even trained
computer and data -handling experts
with advanced degrees in computer science are often at a loss to explain what
in heck many computer dealers are talking about. Personal computing has
become a Tower Of Babel; and as yet
there is no Rosetta Stone the average
hobbyist can use to unscramble computerese-a foreign language even more
complex than French.
In fact, because ELEMENTARY ELECTRONICS is one of only a few national
consumer publications providing extensive coverage of personal computing on
the experimenter and hobbyist level we
are literally drowning in a sea of reader mail, and can no longer answer each
individual letter about personal computing equipment.
Instead, we have compiled the most
frequently asked questions and hope the
answers meet your particular needs and
interests.
For some, the answers will appear
simplistic; but keep in mind we are trying to avoid computerese. Our primary
purpose is to provide you, our reader,
with concrete information you can put
to work. We are not going to try to
impiess you with anyone's expertise.
We know computer equipment represents a substantial investment so we aim
to present our information in the most
useful manner-and that means straight
English.
Question-Since some computer kits are
priced almost the same as complete
computers having built in BASIC and
a keyboard, what is the advantage in
building a kit?
Answer-The complete computers such
as the Apple, OSI, and Radio Shack
generally need a TV monitor for output display, or the computer's output
ELEMENTARY ELECTRONICS/July-August 1978
signal is
lator to
serves as
complete
fed through an RF Moduan ordinary TV set which
the display. At present, the
computers have no peripherals for providing "hard copy" (a
printout). The computer kits, on the
other hand, permit almost unlimited
expansion, though it does get costly
when you add in the cost of a complete terminal: either TTY (teletype), CRT, or Selectric typewriter.
Q-I don't care for
the print quality of
a TTY terminal, nor do my teachers,
who don't accept my homework
printed all in capital letters. Can I
connect a Selectric typewriter terminal to my SWTP 8600 computer?
A-It depends. Most of the rebuilt Se-
lectric terminals you find advertised
in computer magazines are for the
IBM correspondence and EBDC
codes, and they won't work with a
personal computer. Some surplus outfits, however, build in an ASCII converter with an RS -232 output. If you
can find one of these ASCII/RS-232
Selectrics (about $900) you simply
connect it to a personal computer's
serial RS -232 I/O. (Just plug it in.)
Q-/
would like to get my child started
in computing. Which of the beginner's kits in the $100 range do you
suggest?
Processor Technology manufactures the
SOL -20, shown here. The SOL is based on
the 8080 chip, has a self-contained keyboard and utilizes the S-100 bus. It has,
in the smaliest version, 8K of memory and
BASIC in ROM. Available kit or wired.
43
(/(
YOUR COMPUTER
The Challenger lIP, new from Ohio
Scientific, is a personal computer with
4K of RAM, BASIC in ROM, and a captive
keyboard. The CPU is based on the new
6502 chip. Add a RF modulator or connect
directly to a CRT for I/O display.
A-There
is no such animal. Firstly, if
your child is ready to enter High
School, or already there, the school
probably has an introductory course
in either Data Processing or Computer Math. If your child wants to
get into the design end, and has
shown previous interest and ability
in electronics, and really wants to
play and experiment with the electrons, the Heathkit 6800 trainer is
probably the only kit of practical
value. (On a college level it's a whole
different game.)
Q-Which of the computer kit CPUs
do you recommend for a beginner:
8080, 6800, 6502, or whatever?
A-ASR means Automatic Send/Re-
"2.5". Integer BASICS can be powerful in terms of graphics, etc., but
they are useless for any school work
involving even simple arithmetic.
One exception to our rule of "No
integer BASICs" is the Apple II computer, whose 4K resident integer
BASIC is used to load Apple's notably good 16K BASIC.
A-Tough question. The 8080 and its
relative, the Z-80, often use the S-100
bus, for which there are many accessories. Unfortunately, the I/Os (inputs/outputs) are under software
control and it can get somewhat expensive if you need ports for several
peripherals. The 6800 I/Os are memory -mapped and it's cheap and easy
to add peripherals. For example, the
SWTP 6800 computer can handle up
to ten peripherals and you simply
purchase an inexpensive I/O card
whenever you add another printer,
terminal, recorder, etc. Also, the
6800 system allows a good intermix
of serial and parallel I/O ports. You
can do the same with the other CPUs
but at much higher cost. Unfortunately, there are more "gadgets" for
the S-100 bus than for any other
bus or system, so you'll have to plan
ahead.
Some personal computers using the
6502 are extremely powerful, but at
the time this article was prepared
there was little in the way of I/O
equipment or even ports for peripherals.
Q-What is meant by an integer BASIC?
A-It means it cannot handle decimals.
For example, the statement "PRINT
2/4" would return an answer of "00"
instead of "0.5". Similarly, "PRINT
5/2" would return "2" instead of
Q-How much memory would I need
for a computer kit?
A -12K will handle most BASIC interpreters running on an 8 bit system
(8080, 6800, Z-80, etc.) , though
Apple requires 16K for their BASIC.
The Heathkit LSI-11 system is a 16
bit system so you get the same results with half the memory: we
would suggest at least 8K on the
"Big Heath." Few computer kits
come with enough memory to handle BASIC, or even an editor/assembler, so be sure to add in the cost
of extra memory to the basic kit
price.
Q-What
is meant by an "ASR Termi-
nal"?
ceive and refers to a paper tape reader and punch accessory mounted as
part of a teletype terminal. A used
ASR TTY-the model 33-sells for
about $900. Without the reader and
punch you can get one for about
$500 to $600; so if you have no need
for paper tape you can save a bundle
by getting a TTY without ASR. Just
the printer part of the TTY, known
as an R033 for Read Only, sells for
under $300, less than the cost of
most "computer printer peripherals."
Q-What
is meant by "Hardware,"
"Software," and "Firmware"?
A-Hardware is any equipment; computer, printer, even an individual integrated circuit. Software means a
program, or instructions for the computer. Firmware is some form of program or instruction -set already in the
computer, usually called a resident
monitor, that makes it easy for the
user to enter, or write programs.
Firmware is ready as soon as power
is
.ra
_.
applied.
...._
self-contained
computer, with captive keyboard, based
on the Z-80. The smallest version has
4K of RAM and an enhanced Tiny BASIC in
ROM, and is complete with video monitor.
Radio Shack's TRS-80 is a
44
ELEMENTARY ELECTRONICS! July -August 1978
a self-contained computer
with an integer BASIC in ROM, which can
be used to load a 16K BASIC. It includes
at least 4K of RAM, and game paddles, and
will output full -color to a full -color video
monitor or TV set (with RF modulator).
The Apple II is
Q-What is a "Monitor"?
A-See Firmware in the previous question.
Q-What is meant by "Boot" and "Boot
strap"?
A-You have probably heard of the expression "Picking yourself up by your
bootstraps."; meaning, getting yourself started by moving yourself. Same
thing with computers. A computer
can only sit there and do nothing
until programmed; but you can't just
shove a program into the computer;
something must tell the computer
what's going on when you start to
enter your program. A boostrap program is a very small program that
sets up the computer to load a larger,
complex program. To boot a program means to use a program (generally in a resident monitor or operating system) to program a larger
program, or to set up something like
a disk operating system.
Q-An accessory I/O I'm planning on
adding to my home computer has a
feature called "handshaking." Exactly what is a computer's handshake?
A-Handshaking is electronic confirmation that some piece of computer
verts the electrical impulses from
terminals and computers into audio
tones which can be easily handled
by voice -grade telephone circuits.
Some modems, used on private lines,
work at extremely high speeds; the
common voice -grade modems operate at TTY speed (110 words per
minute) or 300 words per minute.
Modems used at terminals are called
originate modems. Those used at the
computer are answer modems. Each
responds to different audio tones: the
originate modem transmits low tones
and receives high tones from the
computer. The answer modems trans high tones and receives low tones.
equipment is ready to execute operations. For example, before a computer transmits to a mass storage de- Q-A group from school would like to
vice such as a recorder it might send
set up a computer we could use from
out an electronic signal to find out if
each home. Is this possible?
the recorder is ready. On receipt of A-Yes. You will need an answer mothe signal the recorder, if ready, will
dem at the computer, and each of
transmit a signal back to the comyou will need a terminal with an
puter that it is ready. The computer
originate modem. Some means must
will then transmit the start signal,
be provided, if there is no one to
followed by the data transmission. If
attend the computer, to automatically
the computer does not get its "handanswer the phone at the computer,
shake" from the recorder it doesn't
connect the modem, and then "hang
transmit data. Handshaking can also
up" when the terminal signs off. This
work the other way: The recorder
is easily accomplished through a momight send out its handshake signal,
dems handshaking signal. (We hope
and automatically feed data to the
to have a construction project on
computer only if a handshake is resuch a device in an upcoming issue.)
ceived from the computer.
Answer modems, and combination
Modems also generally use handoriginate/answer modems, manufacshaking (see next question).
tured by Omnitec-perhaps the most
respected name in modems-are availQ-What's a modem?
able from some surplus dealers from
A-A modem-a term derived from
time to time. You have to keep lookmodulator/demodulator-is a device
ing because answer modems don't
that connects both computers and
come cheap-even used.
terminals through telephone or other
remote -wired circuits. A modem con - Q-Is there some reason paper tape
(teletype) recordings made on my own
computer cannot be fed into my
school's computer, or the time-share
system available through my school?
A-Yes. Even though computers might
use the same CPU there are minute
variations in the encoded signals. It
is more common than not that recordings from one type of computer
cannot be fed to another, even when
using the same type of recording system. For example, one of the most
(Continued on page 90)
Based on the 8080A, the Heathkit H8 has
a 16-key front panel which, in octal
numbers, allows you to address registers
and memory. I/O interfaces and memory
are options, as are petipherals.
ELEMENTARY ELECTRONICS ,July -August 1978
45
CniT1puSER RELU FFILJUUCTS
Here in one place in each issue of e 'e you will find product
information on the newest hobby computers and accessories.
New 6800 Computer-Midwest Scientific
Instruments has announced the MSI
6800, a microcomputer based on the
popular SS-50 bus. The motherboard is
a
full 16 -slot board which offers plenty
of room for expansion. As configured
from the factory, the MSI 6800 arrives
with three boards installed; the CPU
board, a fully -populated 8K RAM board,
and a serial interface board. This leaves
the hobbyist with 13 slots still open for
the future. MSI offers additional 8K
RAM boards for $225 kit and $335
assembled, as well as other accessory
boards such as a cassette interface
board for $75 -kit and $105-wired. All boards are silk-screened and solder -masked.
The power supply section is designed to deliver 5 VDC at 20 amperes to allow
56K of RAM and/or PROM to be used. The plus or minus 15 VDC supplies are
designed to deliver 3 amps each for adequate capacity in powering PROM boards
and other devices. The system has been designed for business, industrial, educational and home environments. With chassis, power supply, motherboard, 8K RAM,
interface adapter, and CPU board the price for the MSI 6800 is $595 -kit and
$895 -wired. Circle number 53 on Reader's Service Card for more information.
-
Home Computer
The Challenger IIP
from Ohio Scientific is a new entry into
the hobbyist computer market. It's fully
self-contained, complete with a full size
keyboard and a 32 x 64 character Video
Display Interface along with an Audio
Cassette Interface. The computer is
equipped with an 8K BASIC in ROM.
The BASIC was designed by the Microsoft Corporation and is bug-free. The
advanced hobbyist may bypass the BASIC and go directly to machine -language,
hexadecimal programming, if he wishes. With 4K of RAM, the computer arrives
ready to go, needing only to be hooked up to a CRT or, through a RF Modulator,
to the home TV set. All the user need do is attach the IIP to a visual display,
hook up a tape recorder for storing programs, and start right in on the most
interet;ting electronic hobby to come along in quite some time. Ohio Scientific
uses their own 48-line bus structure and the IIP will accept many of the present
OSI boards; other accessories such as a special 16K memory board, a matching
floppy disc, along with extended software, are all being planned for the IIP. As
supplied, the. IIP has a four -slot backplane; two of the slots are filled and two
are open for future expansion. Thus, it is a system the hobbyist will be able to
grow into. Complete with keyboard, case, backplane, CPU board, video and
cassette interfaces, the assembled Challenger IIP sells for $598. Circle number 61.
2 -for -1
PROM
ferric oxide formulation. Circle No. 67.
Analog Interface Board-Vector Graphic
says this multi -function Analog Interface
Board permits interfacing with potentiometers, joysticks or voltage sources,
hence it is ideal for hobby and small
business computer applications. An 8 -bit
digital port with latch strobe can be used
as a keyboard input port. Tone pulse gen-
Programmer-Oliver
Audio Engineering (OAE) says this high
quality PP2708/16 programmer programs both the 1K 2708 and new 2K
2716 PROMS made by Texas Instruments. A simple parallel interface connects the PP 2708/16 to any micro computer. An internal address counter
11111111b
makes interfacing a cinch. Only one
unregulated 8V supply is required, and
very little software is needed, to support the programmer, according to OAE.
Simply dump the data via an output port to program a PROM. The programmer
contains address counters, timing and control logic, and a DC to DC regulated
power supply. Each unit comes complete with a black anodized aluminum case,
a five-foot ribbon cable with pre -wired connectors, and software. Prices: assembled and tested, $299; kit, $249; kit without regulators, $199. Circle 71 on
Reader Service Coupon for more information about this product and others from
Oliver Audio Engineering.
46
Cassettes for Hobby and Small
Business Use-AVDEX Corp. makes available a full line of data cassettes specifically designed for use in hobby computers and small business computers.
The cassettes are loaded in 1 -minute,
3-minute and 5 -minute lengths for more
convenient use than are cassettes that
have too much tape for handy hobby/
business applications. The cassettes are
custom loaded with extra short leaders to
prevent the leaders from contacting recording heads, thereby providing instant
start operation and elim nating the possibility of lost data. Prices of the short
load cassettes are: CDC -1, $4.95; CDC-3,
$5.65; CDC-5, $6.35. Also available are
three other cassettes in C-20, C-40 and
C-60 configurations ($4.50, $5 and $5.50
respectively) which utilize the same computer shell components and are loaded
with high quality, high density calendered
Data
erators also can be used to produce
sounds for games or keyboard audio
feedback. Additional features include:
four A to D inputs; MWRITE logic; poweron jump feature for computers lacking
front panels. Prices: kit, $75; assembled,
$115. Circle no. 68 for information.
ELEMENTARY ELECTRONICS/July-August 1978
DUC
AE
puts together in one neat package some of the newest CB rigs,
1antennas and accessories for you to use in CB contacts this year!
Se/e
CB Pistol Mike
new concept in two-way mobile radio
microphones combines an electret -capacitor
element with a compact pistol-grip case that
tucks neatly into the palm. The 1MR Mobile
Ear Microphone, model 40, is specially engineered to be held at the steering wheel
while transmitting, allowing you to talk,
switch, and use both hands for driving
simultaneously. The built-in Velcro pad -lets
you mount the unit anywhere. Just attach
the mating Velcro pad to steering post, dash,
or any other handy surface. The tiny electret A
exact characteristics of the receiver and
external speaker audio response and tune
out off -channel whistles and heterodynes by
a minimum of 70 dB. The PR -1000 is powered from 115 VAC or 12 VDC, includes five
integrated circuits and has a razor sharp
selectivity spec of 80 dB or more. Suggested list price of the AC model is $59.95;
suggested list price of the AC/DC model is
$69.95. For more details, write to Prime
Electronics Inc., 221 West Market St.,
Derby, Kansas 61037.
the antenna vertical. The clamping action
of the Speedy Seizer mount guarantees the
same perfect electrical ground as with a
Snazzy Base
The Superscope Aircommand
CBB-1040 is
a
base station version of the Aircommand
CB -640 which was selected by the California
Highway Patrol for exclusive use in its
vehicles. The Aircommand BPM-1 Power
Microphone is supplied at no extra cost,
providing many times more sensitivity than
conventional mics. The Aircommand CBB1040 40 -Channel CB Base Station Transceiver offers these features: Emergency
channel 9 scanner with flashing light, beeper
CIRCLE 48 ON READER SERVICE COUPON
capacitor microphone picks up your voice
anywhere within arm's reach with exceptional fidelity. There's no need to hold the
microphone up to your mouth when transmitting. The specially designed frequency
response plus the clear, distortion -free reproduction of the electret -capacitor microphone combine to create an on -the -air sound
that punches through noise and interference.
Variable microphone gain lets you adjust the
level for optimum modulation under varying
conditions. Sells for $44.95. Get all the facts
168
Systems
Corporation,
JMR
from
Lawrence Road, Salem, NH 03079.
CB Variable Audio Filter
Prime Electronics new PR -1000 Variable
Audio Filter provides a receive signal improvement by allowing the CB operator to
tune out unwanted interference plus sharpen
the receiver selectivity to exactly match the
desired signal. Operation of the PR -1000 is
quite simple with the selectivity control
varying the amount of audio selectivity
between the receiver and external speaker
from a super narrow 40 Hz up to a wide
10,000 Hz. The frequency control varies the
CIRCLE 72 ON READOR SERVICE COUPON
center frequency of the VAF, once again
from 40 Hz to 10,000 Hz. The Peak mode of
the unit allows the selectivity to be varied
as wide or as narrow as required and the
center frequency to be set to match the
CIRCLE 55
ON READER SERVICE COUPON
"threshold," Channel 9 quick
access switch, LED digital clock, built-in 40
dB speech compressor, SWR metering, RF
power metering, modulation metering, receive signal -strength metering, dual conversion superheterodyne receiver, and many
others too numerous to list. Sells for
$389.95. Get all the facts on the entire
Aircommand line by writing to Superscope,
Inc., 20525 Nordhoff St., Chatsworth, CA
and adjustable
91311.
Magnetic Edge Mount
Antenna
The new Hustler Speedy Seizer, Model
Protect Your CB
Lightning and heavy-duty electrical equipment often create power -line surges and
transients. This can cause extensive damage
to valuable CB equipment. Electronic Specialists newly introduced line -cord transient
suppressors absorb repeated power surges,
SPS,
mobile antenna is for the CB'er who wants
quick on/off installation of a magnetic
mount plus the long-range performance of a
permanent antenna installation. The Model
SPS is designed for fast mounting and removal on cars, trucks, vans, campers, RV's,
farm vehicles, and off -highway equipment
without opening doors or trunk. It has a
unique edge mount that fits any existing
vertical or horizontal 1/4 -in. gap with a
return, such as a door or
5/8 -in. minimum
trunk edge. A heavy -gauge rust -proof 18-8
stainless steel clamp holds the Speedy
Seizer in place. Just a twist installs or removes the SPS for theft protection or car
wash. An adjustable 180° swivel ball keeps
ELEMENTARY ELECTRONICS/July-August 1978
permanent installation. The Hustler Speedy
Seizer is 46 inches long, measured from the
vehicle surface. The 17-7 PH stainless steel
whip and tip rod are very flexible, rust
proof, and will not break. The tip rod is
screwdriver -adjustable for lowest SWR. A
triple -plated chrome swivel ball and high impact plastic parts assure long life. The
Speedy Seizer package includes a 17 -foot
cable with factory RG -58 Belden coaxial
installed connectors. The suggested list price
of the Model SPS is $19.95, and it is available now. For further information on this or
any Hustler product, write to New-Tronics
Corporation, 15800 Commerce Park Drive,
Brook Park, OH 44142.
CIRCLE 77 ON READER SERVICE COUPON
protecting delicate base station CB equipment. Sells for $11.50 (2 prong plug/socket)
and $14.50 (3 prong plug/socket). Units
also available which incorporate transient
suppressor and power line hash filter. Get
all the facts by writing to Electronic Specialists, Box 122, Natick, MA 01760.
49
QUIZ MASTER
by Walter Sikonowiz
Electronic latching stops quarrels from hatching
SHOWS, WITH their big cash
prizes and fast -talking emcees,
have been standard television fare
for more than two decades. Judging
from their vast numbers, it seems that
game shows are as popular today as
ever, although revelations of rigging did
threaten their existence for a time. In
spite of such apparent popularity, however, there is one criticism that few
game shows can escape: Quiz questions,
designed for a mass audience, are usually simple-sometimes ridiculously so.
As an example, consider Groucho
Marx's sarcastic "Who's buried in
Grant's Tomb?" which he reserved for
really inept contestants.
You can improve on the quiz concept with questions of your own design,
but first you will need a priority latch.
This is a device to indicate which one
of three contestants makes the first response to a question. Operation of the
latch is very simple: Each player is assigned an LED and a pushbutton
switch. The first player to press his
switch causes his LED to light and prevents any other player's LED from
lighting at a later time. Obviously, you
can use this device in any game where
it is necessary to detect the first response, so it has a very wide range of
application.
SCR Latching. Let's begin discussion
of the circuit by considering the device
responsible for the latching action: the
SCR. In Figure 1, you can see that the
SCR is a three -terminal device. A
stands for anode, while G means gate,
QUIZ
50
and C indicates the cathode. When normally open pushbutton S2 is pressed, a
current IG flows into the gate terminal.
If IG is large enough, it will cause the
anode -to -cathode impedance to drop;
hence, an anode current IA will begin
to flow. Now, suppose that S2 is released. If IA is greater than a reference
level (known as the latching level) at
the instant that S2 is released, IA will
continue to flow even though the gate
current has stopped. The SCR is now
latched in a conducting state, where it
will remain indefinitely, unless normally
closed pushbutton Si is pressed. Pushing Si interrupts the anode current, and
A momentary pulse at the gate causes the
SCR
to conduct until anode current
is cut.
when Si is finally released, the anode
current remains zero until S2 again
supplies a pulse of gate current. As a
final observation, it is important to note
that the pulse of gate current must last
a finite time-usually a few microseconds-in order for latching to occur.
How It Works. Now, take a look at
the priority latch's schematic diagram.
Three LEDs (LEDI, LED2 and
LED3) are connected in series with the
anodes of three SCRs (Q1, Q2 and
Q3) . Latching of any one of these
SCRs will cause its corresponding LED
to light. Normally, the gate terminals
of the three SCRs are grounded through
R4, R5 or R6. However, if the three
switch assemblies are plugged into J1,
J2 and J3, and if any one of these
switches is pressed, then an SCR's gate
terminal is connected to the collector of
Q5 via R1, R2 or R3. Q5's collector
may be either high or low; if it happens
to be high when a switch is pressed, an
SCR will get latched. If, on the other
hand, Q5's .collector happens to be at
ground potential, no latching can occur.
Let's see just what determines the potential at Q5's collector.
Assume that reset switch S4 has just
been pressed. From our previous discussion of SCR characteristics, it is obvious that none of the three SCRs will
be able to conduct current when S4 is
finally released to its normal (closed)
position. Therefore, the voltage drop
across R7 must be zero since no current is flowing through it. This, in turn,
means that no base bias is applied to
ELEMENTARY ELECTRONICS/July-August 1978
QUIZ MASTER SCHEMATIC
R7
S4 -RESET
S5
120
Q4
LED
LED
LED
2/
3/
RII
R8
100000
02
R9
05
RIO
270000
R2
1000
1000
-
CÌ^
C2
03
RI
--B4
.
27000
01
B1
1000
I
100
<
IÓÓ0
330
Tp3F
10000
JI
This type of circuit is called a priority
latch. Any number could be added.
result that no current can
be flowing out of Q4's collector terminal. Consequently, no current can flow
into Q5's base terminal, and this means
that Q5's collector potential must be
high.
Suppose, now, that we press pushbutton Si and thereby connect Q1's gate
to Q5's collector via Rl. Gate current
will flow, causing Ql to conduct and
LED1 to light. LED1's current causes
a potential to appear across R7, and
this voltage biases Q4 into conduction.
Collector current from Q4 flows
through R9 to forward bias Q5, and
this causes Q5's collector to drop low,
thereby removing Q1's gate bias in the
process. Capacitor C3 slows down the
response of Q5 by about a microsecond
so that Q1's gate drive is not removed
before latching can occur.
What happens if pushbutton S2 is
now pressed in an attempt to light
LED2 by latching Q2? Nothing happens, because Q5's collector is low. As
you can see, the latching of an SCR
precludes the latching of any other SCR
at a later time. While the above argument was illustrated by having Ql latch
first, it is obvious that the same action
results no matter which SCR is the first
to latch. Pressing reset button S4 returns the circuit to its initial state, with
all LEDs extinguished.
Capactors Cl and C2 bypass the
power supply, which, in this case, consists of four AA penlight cells in series,
yielding 6 volts. Maximum current
drain (in the latched condition) is 25
milliamps, which is well within the capacity of AA cells. Unlatched, the circuit draws practically no current. If you
plan to use the priority latch extensively, four C cells could be used instead
of AA cells, with a corresponding increase in battery life.
How It's Made. Construction of the
priority latch is not critical at all; you
may use perfboard, a printed circuit or
whatever you like. The prototype was
constructed in four plastic boxes, with
R6
R5
R4
10000
10000
J2
4J3
parts? Find them
MART-page 83.
Need
QI,Q2
LEDS
Q4, with the
a Q3
04 a Q5
in
HOBBY
ONE OF THREE SWITCH ASSEMBLIES
191
PI
(P2aP3)
III
III
SI
(S2&S3)
CATHODE
ANODE
PARTS LIST FOR QUIZ MASTER
sistor
1.5-volt AA cells in series
B1-four
C1-100-uF, 16
V
electrolytic capacitor
00381
13-phono jacks
LED1, LED2, LED3-LEDs
Pl, P2, P3-phono plugs
Q1, Q2, Q3 -2N5060 SCRs (*)
Q4 -2N3906 PNP
Q5 -2N3904 NPN
R1, R2,
transistor (*)
transistor (*)
R3, R11 -1000 -ohm,
1/2 -watt,
10%
resistor
R4, R5, R6 -10,000-ohm,
-120-ohm,
1/2
RB -100,000 -ohm,
C3-330-pF polystyrene capacitor (Allied 85211, 12,
-watt, 10% resistor
1/2 -watt, 10% resistor
R9 -27,000 -ohm, 1/2 -watt, 10% resistor
R10 -270,000 -ohm, 1/2 -watt, 10% resistor
Si,S2,S3-normally open pushbutton switches
S4-normally closed puhsbutton switch
S5-SPST toggle switch .
Misc.-battery holders; large plastic cabinet;
three small plastic cabinets.
R7
C2-.luF ceramic capacitor
1/2
-watt,
10% re -
*All components identified by an asterisk
available from: Circuit Specialists, Box 3047,
Scottsdale, AZ 85257.
The hand-held contestants's units can consist of almost any type of small box since
all they contain are normally open pushbutton switches. They should be durable.
one large box holding the bulk of the
circuitry. As the photos show, the large
cabinet's front panel contains S4, S5,
the three LEDs and the three jacks.
Each small box houses one pushbutton
switch, which connects to the large
main cabinet via a pair of twisted wires
terminated in a phono plug. Be sure to
use good -quality pushbuttons foi Si,
S2 and S3; small, cheap pushbuttons
are unsuitable because they don't always make contact (especially when
pressed rapidly). Use large, reliable
ELEMENTARY ELECTRONICS/July-August 1978
pushbuttons for best results.
Do not substitute other SCRs for Q1
through Q3. These units were chosen
because of their sensitivity; if you cannot find them locally, you can mailorder them from the supplier in the
Parts List.
A good place to begin construction is
with the fabrication of housings for
pushbuttons Si, S2 and S3. Bore a hole
one-half inch in diameter into the top
side of each of three small aluminum
or plastic miniboxes. In each hole
51
QUIZ MASTER
mount one pushbutton switch. In a
side panel of each minibox, drill a hole
large enough to accommodate a small
grommet.
Now, take two strands of #22 hookup wire, and twist them together for a
distance of about 12 feet. Cut the
twisted pair into three equal -length segments of about four feet each. Solder
the wires at one end of each segment to
the two lugs of a pushbutton, and
thread the other end of the cable segment out through a grommeted exit
hole. Close up each little cabinet using
the screws provided. Then, apply decals
to the miniboxes in order to provide
identification for instance, Contestant
#1, and so on. At the free end of each
of the twisted cables, mount a standard
RCA -type phono plug. This completes
the construction of the switch assemblies, and you can set them aside until
later.
The remainder of the circuitry can
be most conveniently assembled with
the aid of perfboard or a printed circuit. To assist you, a complete PC layout is provided elsewhere in this article.
Once you have mounted all the components on the perfboard or printed
circuit, go back and double-check your
connections. Be on the lookout not only
for improper wiring, but for cold solder
-
joints as well. These can cause you a lot
of grief later, so take the time to make
good solder joints from the start.
Heat Sinks. If you happen to be
squeamish about the possibility of damaging your semiconductors with the application of too tnuch heat, use heat sinks on the leads as you solder them.
For the uninitiated, a heat -sink looks
something like an alligator clip. Attach
the heat -sink to the lead you intend to
solder at a point fairly close to where
the lead enters the transistor package.
You can now really heat the joint to
make a good solder connection without
fear of damaging a semiconductor. Incidentally, be sure that your iron's
power is rated at no more than about
25 watts; more power than this is unnecessary. Finally, use only resin -core
solder in this project-or in any other
electronic project, for that matter.
During the installation of Components. be very careful to properly orient
those devices which are polarized. This
applies to all the semiconductors in this
project, and also to electrolytic capacitor Cl. Biasing diagrams for the various semiconductors can be found elsewhere in this article.
In the prototype, the printed circuit
board was mounted on the inside of the
52
This diagram shows the location of the parts on the Quiz Master's circuit
board and
where the wires from the circuit board go. Note how neat the layout of this project
is-a sure sign of a well designed and carefully planned unit.
dA
l' le
ga ge
Is
,Shgirt1aa
A well constructed printed circuit board can be made by using this template as a pattern for photo etching or resist pen etching. You might even try one of those new
kits that allow a template to be lifted right off the page of the magazine.
large plastic box's front panel. There
was ample space left on the front panel
for the jacks, the LEDs, reset button S4
and power switch S5. In the body of
the case, a 4 -cell battery holder was installed to accommodate the four AA
batteries that power the latch. Construction was completed with the application
of press-on, white decals to identify the
various controls and LEDs. A coat of
clear lacquer sprayed over the decals
will bond them to the cabinet.
Testing. After you have completed
construction, you can test your circuit
like this: ,Plug in all the pushbutton assemblies, and turn on the power. Pressing pushbutton S1 should cause LEDI
to light. Afterwards, pressing either S2
or S3 should have no effect. Now, hit
reset button 54, and verify that the
same priority -latching action is obtained
when S2 or S3 is the first button to be
pressed.
Response time of this priority latch
is something in the vicinity of 5 micro -
The printed circuit board is mounted on
the back of the front cover of the Quiz
Master, between the jacks and the LEDs.
Any 6 VDC power source can be used.
seconds-consderably less than human
reaction time, which is on the order of
milliseconds at best. Consequently, this
circuit will do an excellent job of determining response priority. On the rare
occason when you end up with two lit
LEDs, you will know that the contestants responded either simultaneously
or within a few microseconds of each
other.
ELEMENTARY ELECTRONICS/July-August 1978
by Kathi Martin, KGK 3916
Rathì's
B Carousel
Check out the features on Stoner's state-of-the-art rig
Nothing Lasts Forever!
I
don't know
if "The One Horse Shay" is still studied
in school, but back in my old school-
days (well, not so far back!), everyone
read the poem about the two wheel,
horse-drawn carriage. It was so well
made nothing wore out, until the fateful day all the parts fatigued and the
entire carriage simply fell apart-every
bolt falling out, every seam opening,
every rim splitting, etc.
Eventually, everything breaks down,
components.
particularly electronic
They have not yet succeeded in manufacturing a lifetime transistor or integrated circuit; they do eventually go
bad. Glass encased diodes are known to
shatter; crystals do crack and drift off
frequency or simply stop vibrating; and
well, you name it and it can happen,
as many CBers are just starting to learn.
Each week I get more and more mail
inquiring about transceiver repairs, or
complaining about defective antenna
systems. The plain truth is that transceivers get old, slowly losing receiver
sensitivity, power output, and often stability. On the other end of the coax,
road salts which are used to melt ice
and snow, and even dirty road water,
all wear away antenna hardware. Also,
water gets under plastic-sleeved antennas, the grounding screws on trunk lip
mounts corrode (causing relatively high
resistance), and coaxial cable dries out.
In short, CB equipment-from the
worst to the best-eventually must be
replaced if you want a dependable signal. If you've racked up 10,000 miles
or more on a "permanent" antenna installation now's the time to start looking
for a replacement. If your transceiver
has three or more years on it ask
yourself if you're getting the performance needed for today's communications: Do you need more selectivity?
Does your rig have the wall-to-wall
talk power you now get from even
budget priced transceivers? Do you need
the extra TVI suppression now provided by every FCC type -approved rig?
Most important, does your old rig cover
all 40 channels?
To be perfectly honest, some equipment available in the CB marketplace
today will be no better than your old
worn out gear; it might even be worse.
About the only way to get real inside
info on how a transceiver actually performs as tested by an independent laband one of the very best ways to be up
on what's available in the latest antenna
designs-is by latching onto a copy of
the 1978 CB BUYER'S GUIDE. Unlike
most CB publications that simply reprint the manufacturer's specs in such
a way as to make them appear to be
the results of some form of lab test,
every transceiver listed in the CB BUYER'S GUIDE has actually been tested by
an independent lab, and what you see
are the results of real lab tests.
Even if you're not interested at the
present time in new gear, the '78 CB
BUYER'S GUIDE has a well illustrated
article showing-through spectrum an-
alyzer photographs-why the new FCC
type -accepted transceivers have more
talk power and less TVI. Just this
article alone is worth the price of the
BUYER'S GUIDE.
If you're an active CB'er now's the
time to think about upgrading your
station, and the '78 CB BUYER'S GUIDE
will help you get the best value for
your hard-earned dollars.
The Stoner PRO -40 SSB Transceiver.
Of all the persons hailed as the "Father
of CB," none had the impact of Don
Stoner. CB was a dead issue, an idea
that went no place and had no place to
go until a now defunt magazine called
"Radio and TV News" published an
article on how to build a transceiver for
the then new 11 -meter Citizen's Band.
The author of that article was Don
Stoner, and it was his rig, with its simple superregenerative receiver, that really opened up the Citizen's Band. Copies
of Stoner's rig were built by the thousands, both by hobbyists and "garage"
manufacturers. Even the famous Benton
Harbor Lunchbox (Heathkit) was de -
When you sit down in front of a Stoner PRO -40 CB transceiver you'll be looking at true
state-of-the-art technology. One of the most useful features in this SSB rig is the
"Whistlestop" control. As most SSBers have sorrowfully found out, the predominately
AM signals found on the band can wreak havoc with SSB communications. An AM signal
can heterodyne with a SSB signal, causing a raucous whistling note. With the PRO -40, this
is one annoyance you can tune away. There are all sorts of other features as well, including; true digital readout, null and peak controls, two independent noise blankers,
up and down along with fast and slow channel change buttons, and a D-104 microphone
is included to give you all around talk -power. Circle number 79 for more information.
ELEMENTARY ELECTRONICS, July-August 1978
53
filter) .
KATHI'S CB CAROUSEL
signed using Stoner's idea as the foundation. For almost a year, the parts
needed to build Don Stoner's CB rig
were almost impossible to get because
hobbyists snatched them up as fast as
the radio parts stores could get them
in.
Don Stoner moved on to become one
of the big names in commercial sideband equipment. Now he's back again
in CB, with a sideband rig that's probably the ultimate in sideband-only
equipment.
Known as the PRO -40 Transceiver,
Don Stoner's latest contribution to CB
has just about everything you can imagine, and then some extras you probably never believed could exist.
First, the PRO -40 is sideband only; it
has no AM. If you want to work AM
you feed your AM rig, through the
PRO -40 via a standard coax conector
on the rear apron. The AM signal feeds
through the PRO -40's TVI filter, and its
frequency is displayed by the PRO -40's
digital frequency counter display.
(More on the counter later.)
Because the PRO -40 is designed exclusively for sidebanders, it has a special feature that gets rid of AM station
interference. Called a "Whistlestop," the
device is a tuneable filter that tunes out
the heterodyne interference (whistle)
caused by an AM station operating on
a channel being used for sideband.
But, I'm getting ahead of myself.
Let's start at the beginning so we can
look at all the important features in
the PRO -40.
The LED digital display indicates the
channel number, the actual transmitter
output frequency to 100 Hz, and the
letter L or U to indicate the lower or
upper sideband. The frequency display
is a counter that also indicates the frequency of an AM transmitter fed
through to the antenna.
The operating channel is selected by
simply depressing up and down channel -change buttons-both fast and slow
buttons are provided.
A multi -turn clarifier provides up to
±5 kHz of fine tuning, the precise
amount of tuning off the center channel
being indicated by the counter display.
A switch labeled null causes the
whistlestop to function either as a null
filter to reject heterodyne whistle interference, or as a peaker to enhance a
narrow range of received voice frequencies -very useful when the received
station has muddy sound. (You can
peak the higher frequencies with the
54
Other aids to getting the best possible performance include two independent noise blankers with individual
selectors, and a microphone equalizer.
The PRO -40 is supplied with a D-104
mike, which puts the talk power several
notches above what you would usually
expect from the cheap mikes supplied
with many rigs. When the going gets
too tough for even the D-104, pressing
a switch labled MIC cuts in a slight additional microphone preamplification
and adds a tilt towards the high fre-
AUDIO OUT
AUDIO IN
SWR
As for performance. Zowie! You've
got to try it to believe it. Receiver sensitivity measured 0.3 uV for a 10 dB S+
N/N ratio (signal plus noise to noise).
Selectivity was somewhere beyond the
80+ dB of our measurement equipment. Stoner claims 90 dB and it's possible he is correct because we couldn't
find the limit at 80+ dB.
The AGC (automatic gain control)
action was an unbelievable 0.5 dB between the normal input signal test range
of 2 to 10,000 uV. I could hear no
change in speaker volume when a
AM TRANSCEIVER
FUSE
ANT. OUT
INPUT
The PRO -40 has a complete set of input/outputs on the back panel. Note the AM transceiver input. This is a SSB-only rig and operation on AM requires an outboard transceiver
which
is
fed into the PRO -40's frequency counter so as to display operating frequency.
quencies to the overall frequency response, thereby providing extra talk
power to the intelligence -carrying voice
frequencies. (For a local contact it's
easier on the receiving operator's ears if
you keep the MIC switch in the normal,
or flat position.)
A dual (two) meter provides some
unusual built in indications. One meter
provides the usual S/RF indication,
but with a difference. The RF output
function indicates the peak envelope
power output (P.E.P.) as you modulate. The other meter movement built
into the same case provides an unusual
antenna condition indication. When the
meter shows center scale the antenna is
properly tuned. If the antenna system is
tuned above or below the operating
frequency it will be so indicated by
the meter. If the meter indicates below
center scale it is tuned below. the operating frequency. (This sure beats a
standard SWR indication.)
The power supply is 120 VAC. A
terminal strip on the rear provides
nominally 14 VDC for powering associated equipment such as a mobile transceiver used for AM. The strip also has
terminals for a speaker; there is none
inside the cabinet. (Pick a really good
communications -type speaker for the
PRO -40.) If desired, you can monitor
received signals through headphones
connected to a front panel headphone
jack.
strong local signal walked on a very
weak signal. Speaking of strong signals,
the receiver is immune to overload
under worse -case operating conditions;
while testing the PRO -40 a local opened up with his mobile right outside my
door and did not cause overload or
cross modulation-that's performance at
its best.
As for the transmitter, it produced
exactly 12 watts P.E.P. over all 40
channels. Microphone sensitivity in the
normal (flat) mode was 45 dB-sensitive, but not so sensitive it picks up
every sound in and around the house.
Even though the PRO -40 requires
an outboard AM transceiver to operate that mode-you may find yourself enjoying AM more than ever before. The reason? When you feed the
AM output of a transceiver into the
special jack on the back of the PRO 40, you avail yourself of both the
PRO -40's TVI filter and its frequency counter. It's a real kick to
operate with a frequency readout in
LED digits, something you just can't
do with most AM sets.
There's just so much to say about the
PRO -40 I could go on and on, but it's
time to close. Summing up, the Stoner
PRO -40 is the gold-plated special of
super-performance transceivers. I suggest you get the full story direct from
Stoner by circling No. 79 on the reader's service coupon.
-
ELEMENTARY ELECTRONICS/July-August 1978
by James A. Fred
Run rings around long wires with these BCB loops
HELLO OUT THERE in Radioland.
How is your collecting going this summer? Have you registered for the AWA
annual conference? It will be held at
Canandaigua, New York again this year
and promises to be bigger and better
than ever. The dates are September 29
and 30, 1978. I hope to see many of my
readers there.
Looping the Loop. Several readers
have written to me asking about antennas for their radios, and especially
about loop antennas since many of the
radios built in the 1923-1926 era had
these antennas. The outside antenna
consisting of 100 feet of wire hung between two glass insulators, as high in
the air as possible, was one drawback to
radio ownership in the 1920's. Apartment dwellers soon found there wasn't
any way they could erect an efficient
outdoor antenna. Atwater Kent went to
great lengths in his instruction books to
show listeners how to put up outdoor
antennas.
In large cities where there were many
broadcasting stations only 10 to 30
miles from the listeners a loop antenna
became a successful substitute for an
outdoor antenna. The loop antenna usually consisted of several turns of wire
wound on a wooden form varying in
size from a square one -foot on a side
to a square four feet on a side. In spite
of its small size it would receive almost
as many stations as an outdoor antenna.
In addition to its compactness another
advantage to the loop antenna was that
a ground wasn't necessary with the
loop. One big advantage to a loop antenna is its directivity. In most cities
there is much electrical interference and
man made noise. The loop antenna
picks up the loudest signal when the
loop is turned so its flat side faces in
the direction of the station. If the plane
of the loop is at right angles to the
station very weak signals are heard.
Thus by rotating the loop unwanted signals may be attenuated or nulled out
leaving the desired station to come in
free of interference.
The method for making a loop may
vary mechanically, but the following information can be used if you want to
build a loop for a radio that never had
one or if you want to replace a loop if
the original is lost or broken. For most
purposes the wire used for a loop can
be number 20 or 22 bare copper wire.
If you can find some cotton covered
stranded wire it will make a loop look
very much like an original. The strands
of wire can be spaced from 14 to 1/2
These three diagrams show how the loops
are connected to various receivers of dif-
A
Turns of wire
I
I
12
DESIGN CHART FOR
Cross -arm length
B. inches
Length of Litz
wire, feet
125/64
66
I
52
135
117
105
92
Spacing °C;'
inches
13
14
3/4
43
9/16
3 5
15
29/64
3/8
9/32
I6
1
7
fering internal wiring arrangements.
LOOP ANTENNAS
0
26
13/16
2
1/2
81
3
1
77
67
Use this chart to determine the amount of wire needed for a loop antenna with the
length of the crossbeam and spacing desired. Use closer spacing on a small loop.
ELEMENTARY ELECTRONICS/July-August 1978
inch apart. A loop made on a four -foot
square wound with six to eight turns of
wire and tuned with a .001 mfd. capacitor will cover the whole broadcast
band. If the size of the loop is smaller,
the number of turns of wire must be
increased. Thus for a 20 -inch square
there should be about 16 turns of wire.
In general about 100 feet of wire will
be needed for a loop. It is evident that
as the loop gets smaller in size it begins
to resemble the conventional tuning
coil.
55
ANTIQUE RADIO CORNER
With the chart shown it will be a
simple task to make a loop which will
work with most of the three -dial tuning
battery receivers. The first thing to do
when building a loop is to decide how
big to build it. Then you can find the
number of turns of wire and the spacing from the chart. Let's assume that
you want to build a loop 20 inches on a
side. On the graph on this page follow
the line up through 20 inches to the
one inch spacing curve and from that
point to the left. This shows about 20
turns are needed; 18 turns are needed
for 3/4 inch spacing; 15 turns for 1/2
inch spacing; and 12 turns for 1A inch
spacing. The table shown will give exact
dimensions and length of wire needed
for various size loops. The table specifies flexible, stranded wire, but probably
it will work OK with plastic covered
stranded wire. The inside turn of the
loop should be connected to the antenna binding post of the radio.
Now that you have designed and
built a loop antenna how do you connect it to your radio. The method of
connecting a loop to your radio depends upon the wiring inside your
radio. If the set has an antenna coil
and tuning capacitor connected in series
then the loop is connected in series
with them. If the receiving set has a
coil only then a tuning capacitor must
be placed so that one of its terminals is
attached to the loop and the other to
the ground connection of the set. Then
the inside turn of the loop is connected
to the antenna connection of the set. A
loop and tuning capacitor may be used
to replace the tuning circuit of the RF
A
TYPICAL LOOP ANTENNA
nnwunni
%/%
SLOTS FOR
WIRE
WOOD,
RUBBER OR
BAKELITE
BRONZE
TO RECEIVING
SET
This is a typical, concentrically wired loop
antenna. The desired length and spacing
can be determined from by using an average
of the inner and outer measures of the cross
beams or sides of the loop wires.
56
A homemade loop antenna typical of the
1920s. Compactness and directionality made
it popular with city dwellers.
amplifier stage in the radio. In this case
the tuning capacitor is connected across
the grid and filament connection where
the original tuning coil was connected.
With a loop antenna you needn't worry
about a lightning arrestor as you would
with an outside antenna.
Who Was Baby Jacquelin? Some time
ago a collector friend, Frank Heathcote
of Logansport, obtained a very unique
crystal radio receiver. He purchased it
from a collector who lived near Toledo,
Ohio. As you can see from the photo
it is a plaster statue molded in the
shape of a young girl sitting on a box.
The girl seems to be dressed in the
costume of the French Foreign Legion.
Her head covering seems to be a Fez
with a tassel. She is holding a staff or a
cane, I am not sure which. It has been
suggested that the girl is Shirley Temple
dressed for a part she may have played
in a movie of several years ago. Molded
into the front of the box are the words
"Baby Jacquelin."
The photo of the back shows a mineral detector, a cat whisker, switch
points with a contact arm, and two
phone tip jacks mounted on a black
phenolic panel. Extending from behind
the panel are two wires, possibly the
antenna and ground connections. The
statue is just as Frank bought it with
the exception of the spring clips and
insulators on the two wires.
Frank and I are both anxious to
know all about this crystal radio statue.
How old is it, who made it, where was
it made, and who was the girl? We also
wonder if the radio receiver was originally mounted in the box or did someone build it in after the statue was
made? If you have any knowledge of
this radio or the statue please write to
me in care Of ELEMENTARY ELECTRONICs magazine. I will publish the best
information I receive for the benefit of
all radio collectors.
A Radio Collector Needs Help! I received a telephone call from Mr.
George Ray of Klamath Falls, Oregon
in regards to a 1938 German made
Phillips radio. It was built after Adolph
Hitler rose to power in Germany. He
has seen the same model radio in two
different WWII movies on TV that
showed German Soldiers in their rooms.
The radio is a small table model containing two vacuum tubes. The one tube
whose number I don't have is no problem since he has two new spares. The
other tube is a VCL 11 and has a crack
in the glass bulb which has caused it to
loose its vacuum. Mr. Ray was overseas several years ago, but was not able
to find the VCL 11.
Here is the problem: he hasn't been
able to find any information on the
tube, he doesn't know of any replacement type for it, he suspects that there
were two tubes in one glass envelope
because of the way the connections on
the tube are arranged. The radio played
when he got it and he wants it to play
again.
If any reader has a VCL 11 vacuum
tube or knows of a replacement for it I
would appreciate it if he would write to
me in care Of ELEMENTARY ELECTRONICS magazine, and I will relay the information on to George Ray.
GRAPH FOR DESIGNING
A LOOP ANTENNA
221/41
1/2° 3/4" I" SPACING
20
18
16
N14
rr
z
12
~10
08
:A
w 6
m
D4
z
2
o
10
15
20
25
30
35
LENGTH OF SIDE OF COIL IN INCHES
40
This chart is used to design coils if the
length of the side of the coil is known.
ELEMENTARY ELECTRONICS 'July -August 1978
CALCULATOR
Amp
CARPENTRY
Build our calculator stand
and don't take weak
batteries lying down!
by John Boyer
The "Baby Jacquelin" crystal radio statue is
of unknown origin. The insulated aligator
clips are a recent addition.
Reader Feedback. Some time ago I
mentioned having. a Garod radio that
looked like it had been rewired from
its original manufactured state. Frank
Pagano of Meriden, CT sent me the
following information. I quote from his
letter as follows: "No doubt your
Garod radio has been modified because
my belief is that it was originally a
model EN. The model EN had four
AC -100 tubes, one type 10 audio output and an 81 or UX216B for the rectifier tube. I have a Garod like yours,
but it is a model EA and has three
UX112, one UX99, a type 10 and an
81 rectifier tube. The tube type AC 100 is extremely rare as I only have
one."
I am always happy to hear from
readers of ELEMENTARY ELECTRONICS,
especially when they can supply information about radios we have questions
about.
We received an entirely different
kind of letter from Ray Zorn of Berne,
Indiana. Ray worte a poem back in the
early 1930's that was published in
Radio Guide magazine, volume 1, number 46, for the week of September 4,
1932. If any reader has this magazine
as well as an issue a few weeks later in
which a reader commented on Mr.
Zorns poem I would appreciate hearing
from him. I will put Mr. Zorn in touch
with him.
So long for now. We will be back
again next issue with news and views
on the antique radio collecting hobby.
How WOULD YOU LIKE to turn your
small hand held calculator into a desk
model that can operate for a long time
for very little cash? You won't need to
replace batteries very often nor will you
have the nuisance of the AC adapter's
line cord running from your calculator
to the 117 volt wall socket. You can
very easily make this accessory for your
calculator, and it's well worth the effort.
The cash and trouble it saves is nice,
but too, you'll really enjoy the enhanced
"feel" of your calculator.
As there are many variables, it is not
possible to be specific with instructions
as how to build this accessory for
your calculator. Use your own imagination and creativity to build the stand to
suit your needs. By following the outline and b`y looking at the photographs
there should be no reason why you
would have any trouble at all with this
project. It's simple-and its simplicity is
Why spend a fortune on batteries for your
calculator? Here's a way to not only save
on battery costs, but to enhance performance by turning a hand-held into a desk
model! The project is simple and easy to
do. The type of cabinet is all up to you.
Once built, the stand can be easily disconnected from the calculator. It's a convenience you'll wonder how you did without.
Get busy building and save yourself dough.
ELEMENTARY ELECTRONICS/July-August 1978
one thing that makes it such a "fun"
project! Build a wooden box that is big
enough to hold the number of "D" cells
it would take to run your calculator.
Connect them in series. Each "D" cell
is 1% volts. Build the box, which doubles as a stand, so that the calculator
sits on top at an angle that makes
viewing the readout comfortable to
you. Cut off about 6' of cord from the
calculator plug end of the AC adapter.
The plug will then go in and out of the
calculator as you wish, and the other
free end of the cord then has to be
hooked to the + and side of the "D"
cells which have been placed in "D"
cell holders inside the wooden stand.
Be sure you get the polarity correct
when you hook up the cord to the "D"
cells. (You can hook up your AC adapter to the wall socket and check the
polarity of the plug with a DC voltmeter before you cut off the 6" strip of
cord at the calculator plug end) . Paint
the wooden stand as you see fit. I put 4
small felt pads on the bottom of the
stand to cushion it from whatever it
sits on. The calculator pops in and out
of the stand very easily. If you want to
take the calculator out of the home or
office, simply pull the plug and lift the
calculator out of the stand and away
you go. Always leave the calculator's
internal batteries in if you plan on taking the calculator out of its stand. The
internal batteries are not in use as long
as the plug from the "D" cells is in the
AC adapter socket. Once the plug is
pulled the internal batteries of the calculator are again in use.
A Calculated Savings. The more you
use the calculator in its stand-the
greater will be your savings. By using
my calculator and stand nearly every
day for several hours, it ran for 16
months from one set of Alkaline "D"
cells. I don't know how many hours
that would be of continuous usage, but
I do know that I was replacing the
small "AA" batteries in my calculator
every month before the stand.
-
57
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59
HEARING
HOLLAND
We'd
like to
DX
the Netherlands:
Wooden Shoe???
by Brian A. Rogers
IN 1926, WHEN THE INFANT broadcasting industry was taking its first
electronic steps, a group of engineers, employed by the Philips electrical factory in Holland, began experimenting with the mostly unused "shortwave" portion of the radio spectrum. A
transmitting station, bearing the call letters PCJ, was established at the company's factory at Eindhoven.
On March 11, 1927, a little more
than fifty years ago, the experimenters'
efforts brought results. A transmission
on a frequency of 10 MHz, powered
with a feeble (by today's standards)
10 kW, was received by an amateur
radio operator at Bandung, Java, in the
Dutch East Indies, a country now
known as Indonesia.
The listening ham, excited by hearing something originating so far away,
immediately wrote the Philips people
and told them of his reception. The
engineers were delighted to learn that
signals from their station had travelled
so far.
Eddy Starz, then a PCJ announcer,
and later host of the station's popular
"Happy Station" program remarked,
"Shortwave has done away with our old
enemy-distance," a statement which
has been proven accurate countless
times since.
PCJ continued its experiments into
the 1930's, a decade during which it
moved its transmitting site from Eindhoven to Hilversum, Holland. At Hilversum, the Philips scientists discovered
that mounting an antenna on a platform, and rotating the platform by
means of rails beneath it, enabled energy transmitted by the antenna to be
"aimed" at a "target" area. This was a
forerunner of the many efficient "beam"
antennas which are in almost universal
use by present-day international broadcasters.
PCJ was forced to stop transmitting
during World War II but, known as
60
The Netherlands, certainly one of the world's
most scenic countries, attracts its due share
of Europe -bound tourists. You can stroll
down the narrow streets in the city center,
streets which have been closed to traffic
to make room for people and shops; ride a
windowed boat down the Singel canal beside the colorful Amsterdam flower market;
or visit historical monuments and sites such
as the Montelbaenstorne Tower which was
built around 1512 as a fortification in the
city walls against invading armies.
"Radio Nederland," the station resumed
operations on April 15, 1947.
Today, Radio Nederland programs
are heard and enjoyed by SWLs around
the world. Because of Radio Nederland, Holland has an electronic voice
far stronger than countries of similar
population and geographical size.
Signals from 100 kW transmitters in
Lopik, Holland, and 300 kW transmitters on Bonaire in the Caribbean and
on Madagascar in the Indian Ocean,
reach most parts of the globe with ease.
A staff of 370 people, produces programs that in 1963, 1968 and 1973,
won for Radio Nederland first place in
a popularity poll conducted by SWLs.
The station has also received the Merit
Award of the National Association of
Educational Broadcasters.
Some of the best news -reporting on
the high -frequency bands is heard during the twenty -minute -long "News block" programs, one of which opens
each transmission. The first seven minutes of each Newsblock is devoted to
a review of current world happenings,
while the remaining time is taken by indepth looks at the background and history of present international events.
Variety is the theme of Radio Nederland's musical programs. Besides
ELEMENTARY ELECTRONICS -/July -August 1978
1awlK,r.t a k
*16
.!
as "Shortwave Propagation," "DX
Receivers," and "The All Round DXer's Course." No tuition charge is made
for this instruction.
Receiving Radio Nederland is no
problem for North American SWLs,
even those who have only inexpensive,
transistor portable receivers. Three
eighty -minute -long transmissions are
broadcast daily to those listeners. The
first, broadcast weekdays only, is aimed
to Eastern North America. Transmission is from Lopik on 11,730 and 9,715
kHz beginning at 2130 GMT (4:30
titles
Radio Netherland does its best to bring the
spirit of Holland to its listeners. Be.
sides broadcasting in many languages
..
to listeners all over the globe, the station
unique aids available to its DXmakes
ing audience. Free to all are data sheets on
such topics as crystal calibrators and antenna tuners. There are also technical correspondence courses for which there is no
tuition charge. Lively programming too
attracts a worldwide audience, along with
attractve and colorful QSL card veries.
...
and Spanish languages.
broadcasting the latest offerings on the
Radio Nederland does not neglect its
Dutch and international pop hit paDXing
listeners. In fact, it offers unique
symphonic
station
plays
rades, the
benefits to DXers. Free to anyone who
music performed by the world's finest
writes for it is the "DX Information
artists.
Service Catalog." Described are data
No description of Radio Nederland's
sheets on such topics as crystal calibraprograms would be complete without
tors, antenna tuners and interference
mentioning the Sunday "Happy Station" music and variety show. Begun suppression, as well as booklets about
more than forty years ago by the late , antenna and convertor construction. All
are sent at no charge to interested
Eddy Starz, Happy Station is now ably
listeners.
hosted by Tom Meyer.
Also popular are Radio Nederland's
Besides English and, of course,
technical correspondence courses. WritDutch, Radio Nederland currently often by the station's Jim Vastenhoud and
fers transmissions conducted in the
other experts, the courses include such
Afrikaans, Arabie, Indonesian, French
ELEMENTARY ELECTRONICS/July-August 1978
P.M. EST.) The second, heard every
day at 0200 GMT (9:00 P.M. EST.)
comes from Bonaire on 6,165 kHz. The
third transmission, meant for West coast
listeners, is broadcast by Bonaire every
day at 0500 GMT (9:00 P.M. PST.)
on 9,715 and 6,165 kHz.
One of Radio Nederland's "don't
miss" offerings is "DX Juke Box,"
heard every Thusrday right after Newsblock. Hosted by Dick Speekman, the
program features news of SWL club
activities, predictions of future ionospheric conditions, and DX reception
reports from such places as the United
States, Sweden, the South Pacific and
Asia. Harry van Gelder, the program's
former emcee, was recently honored on
his retirement by having his picture
printed on a special Radio Nederland
QSL card.
Long noted for its attractive QSL
cards, Radio Nederland continues to
send these verifications in return for
correct, written reception reports. To
earn a QSL card the writer's report
must contain the date and time (in
GMT) of the broadcast heard, the frequency being used and some details of
the programming heard during the
broadcast. Reception reports should be
sent to Radio Nederland, Box 222, Hilversum, Holland. This address can also
be used when requesting program
schedules, the DX Information Service
Catalog and details of the various correspondence courses.
61
Why not build projects you can be proud
of, in appearance as well as circuit design? It is neither difficult nor expensive
as you'll note when you follow this unit
on a step-by-step journey from a blank,
machined panel to real artistic beauty.
1.
now-the finished project, a delight to the eye! Once you try this method
on one of your projects you'll never go
back to ugly again. You don't have to be
an artist, and it does not add much to
the cost. Electronics can be beautiful!
14. And
l
2. You will need spray and brush -on protective coating, plastic tape, various types
of rub -on lettering and designs, and a
burnishing tool (the white cylinder) to
effect the transfer of the letters from the
carrier sheet to a project's front panel.
GIVE birth to an electronic project, don't send it into
the world illiterate. As shown in
this article, it's easy to apply lettering
and designs to give your projects a professional appearance, as well as for
functional reasons. This is accomplished
by using a product called rub -on lettering (or dry -transfer lettering), which
consists of letters, numbers, or designs
with an adhesive on their back side so
that they can be affixed to a panel or
other surface. The letters come attached to the back of a transparent
plastic carrier sheet, from which they
are transferred to the panel by rubbing
or burnishing. Follow the photos to see
how it is done. The process may seem
complicated at first, but with a little
experience you will find that the steps
go quickly.
Rub -on lettering is available in various sizes and colors (black and white
are the most common). Sets may contain complete words, individual letters
or numbers, or a combination of these.
Sets consisting of index marks and other
fied with it. Using the quadrille paper,
as pictured here, makes the job easier.
WHEN YOU
LOVE THAT
Press -on decals will turn
by Randall
designs for rotary switches and dials
are also available.
A small set, which should see the
average hobbyist through half a dozen
projects or more, costs only about two
dollars. Your local electronics store
probably carries rub -on lettering and
related supplies, if not, try the suppliers
listed at the end of this article. Rub -on
lettering is also available from art,
graphic arts, and office supply stores.
Although the type they carry is intended
primarily for other purposes, it can he
used for electronic projects.
In addition to the lettering and a few
household items (cellophane or plastic
-,.foute.
13. Here you see what the panel looks like
after the lettering has been completed but
before the parts have been mounted. It already has a clean, professional look,
more like something out of an assembly line factory than from your workbench!
r
12. You can also buy spray overcoating as
pictured here. Spray is more even than the
brush -on, but the brush -on can be applied
thicker. This method too requires that you
carefully check for the compatibility of
the overcoat with both letters and panel.
62
You can't fashion it if you have never
seen it before-at least seen it on paper.
First, make a sketch and work on the
arrangement until you are quite satis3.
11. You'll want to protect that final panel,
and there are two methods you can use.
Here we show the brush -on method of
overcoating. First, check on a scrap or
hidden area for compatibility with both
rub -on lettering and the panel finish.
ELEMENTARY ELECTRONICS/July-August 1978
4. Once you
know where it
is all
going to
be at, you can begin to machine the panel.
Follow your quadrille -paper layout carefully and don't make last minute, poorly planned changes! Then make certain the panel is
clean and dry and free of any imperfection.
LETTERING
projects into works of art
Kirschman
tape, ruler, paper, etc.) , you will need
a blunt -pointed tool to burnish the letters into place. Tools for this purpose
can be obtained where art supplies are
sold, or you may be able to find something around the house that will serve
the purpose. However, a pencil or ballpoint pen tends to be too sharp, and
may also obscure the lettering. The
burnishing tool shown in the photos was
made from 1/4 -inch diameter plastic rod
sanded round on one end and tapered
and rounded to about Vs -inch diameter
on the other end. It could also have
been made from a wood dowel.
The panel or other surface to which
desired letter (or word, or
design) on the carrier sheet, place it in
position on the panel and press the sheet
against the panel. The back of the sheet is
tacky so it will not easily slip. Here we
have already applied some of the letters.
5. Locate the
you intend to apply the lettering should
be clean and dry. Any oil, grease, dirt,
or moisture will hinder adhesion of the
lettering. Soap and water can be used
for cleaning, except on bare aluminum.
Rinse and dry the panel thoroughly;
after wiping off excess water, use a
heater or warm oven to dry. Solvents
can also be used for cleaning; test first
for compatibility with the finish. Do
not use a heater or oven with solvents.
To clean bare aluminum, solvents can
be used, or chemical preparations for
this purpose are available from paint
and hardware stores. After cleaning do
not touch the areas where you will
apply the lettering.
If you use solvents or other chemicals be sure to follow the manufacturer's directions and particularly observe the appropriate safety precautions.
Spend a little extra time and effort to
be safe and minimize the possibility of
injury.
After you have applied the lettering,
you will probably want to protect it
(Continued on page 96)
letter to the panel by use
of the burnishing toòl. Rub over the letter
several times, increasing the pressure each
time until the transfer is complete. As you
do this a slight change in the letter's
appearance verifies transfer is working.
6. Transfer the
7. Peel the carrier sheet away from the
panel, starting from one end and holding
the other end in position against the panel.
Check that the letter has completely transferred. If it has not, all you have to do
is lay the sheet back down and burnish over.
8. Make
lettering is applied, and you
are satisfied with it, burnish one more
time. Use a backing sheet of slick paper,
so the lettering will not stick to the backing sheet, and go over the whole panel.
Use the blunt end of the burnishing rod.
10. Once all
Positioning index marks is done by
temporarily mounting both a switch 'and its
knob. Turn the knob to each position and
align the mark with the pointer. As you
see here, the number "1" makes a good index mark, certain other letters may be used.
9.
ELEMENTARY ELECTRONICS/July-August 1978
a mistake? It's no disaster. To
remove an error, press ordinary cellophane or plastic tape over the offending
letter and then simply lift it off. This
may be repeated if needed, until all is
clear. An eraser may also be used.
63
DXing OUT-OF-BOUNDS
You'll hear a lot more
stations when you listen
outside the SW Bands
by Harry L. Helms Jr.
3
A LOT OF SWL/DXERS keep strictly
in bounds when they're at the dials. No,
that doesn't mean they do all their lis-
tening on a basketball court or football
field. "In bounds" DXing is when one,
restricts all DXing to the standard, internationally allocated broadcasting
bands. Now there's nothing wrong with
DXing only shortwave broadcasting stations, but there is something missing.
A glance at your logbook and QSL collection will tell you what's missing:
places such as American Samoa, Bermuda, Greenland, and Hong Kong!
And countries like Iceland, and the former French colony of Afars and Issas
operate shortwave broadcast stations
but they're really tough to hear in
North America.
Simply put, if you want that logbook
and QSL collection to grow, you've got
to start DXing out of bounds-outside
of the standard international shortwave
bands!
Point-to -Point. It sometimes seems
that the international shortwave broadcasting bands are civilization while the
rest of the shortwave spectrum is an
untamed jungle. But that's misleading.
In fact, there is one class of "out of
hounds" stations that are probably easier to DX and verify than many outlets
in the shortwave broadcasting bands.
These stations are the point-to-point
utility stations.
Utility stations, as their name implies, are stations that do work of some
sort instead of broadcasting. Point-topoint utilities relay messages of some
sort from one fixed location to another
fixed location. Many international broadcasters, such as the Voice of
America and . Radio Nederland, use
point-to-point stations to relay transmissions from their studios to their overseas relay bases. Perhaps the largest use
at present for point-to-point utilities is
to relay overseas telephone calls between countries that do not have satellite transmission facilities.
It just so happens that many of the
64
Point to point DX can take you
to exotic Tahiti, bustling Hong
Kong or to busy communications
terminals such as St. Johns, Newfoundland, shown on the right.
countries lacking adequate satellite communication facilities (and therefore use
point-to-point utilities) also happen to
be very rare or even impossible to DX
on the international shortwave broadcasting bands. To hear them, you'll have
to DX the point-to-point utilities-and
that makes for DX-citement!
Marker Magic. It might seem difficult
to identify any point-to-point stations
you happen to hear if they are used
mainly for handling such things as telephone calls. Fortunately, there's a handy aid for DXers that makes identifying and verifying the point-to-point stations a snap. It's called a marker transmission.
A marker transmission is a repeating
tape recorded voice message that typically runs something like this: "This is
transmission for receiver adjustment purposes from the overseas radiotelephone terminal located at Warsaw,
Poland." The vast majority of markers
heard are in English, although it is common to hear another language, such as
French or Spanish, used in addition to
the English. In scattered cases you'll
find music used as well, particularly in
markers transmitted from the People's
Republic of China.
Why do point-to-point utilities use
markers? The primary purpose is to allow the sending and receiving stations
to test and adjust their equipment prior
to actual operation. Markers are used
to fill empty air time between messages
a test
as well.
Markers make it super -easy to prove
your reception of a point-to-point util-
ELEMENTARY ELECTRONICS/July-August 1978
You can DX Greenland (left)
out-of-bounds on 11612 kHz or
Shanghai China (below) on
13740 kHz. These point to
point utility stations identify
themselves in English. Don't repeat communications you hear.
Point to point utilities connect the out-of-the-way places
to major communications centers such as London (left) Paris,
Rome, New York and Tokyo.
ity stations. All you have to do is to
copy the text of the marker word for
word! And since markers are repeated
over and over for a period of several
minutes, it's quite easy to get the entire
text.
Digging Them Out. If you're accustomed to the orderly schedules of stations in the international shortwave
broadcasting bands, you may be in for
a shock when you start DXing the
point-to-point utilities. Fixed schedules
here are virtually unknown. But this is
as much of an advantage as it is a disadvantage. While you can't tune in a
certain frequency at a fixed time, the
opportunity exists for point-to-point DX
at virtually any hour of the day or night
you choose to listen.
Our table of point-to-point frequency
allocations will show you where to tune.
Remember, however, that these are
rough approximations. Listeners in the
East will have more chance to hear
Europe and Africa and listeners in the
West will have more luck in hearing
Asia and the Pacific.
The bulk of marker transmissions
will be in single sideband (SSB), although some still use amplitude modulation (AM) . To copy SSB you'll need
a receiver equipped with a beat -fre-
quency oscillator (BFO). You'll be able
to recognize an SSB transmission by its
distinctive "quacking duck" audio. Tune
in the signal for maximum reading on
your S -meter or loudest volume and
then switch on your receiver's BFO.
Adjust the BFO for the most intelligible
audio. Many newer receivers have a
fixed BFO indicated by such positions
as USB (upper sideband) and LSB
(lower sideband) on the receiver's
mode selector. To tune in SSB markers
on such a set, select which position
offers the best copy. Often some slight
retuning might be necessary. On older
receivers it often helps to turn the volume control all the way up and use the
receiver's RF (radio frequency)' gain
control as a volume control. On some
receivers the RF gain control is labeled "sensitivity."
Business Hours. Since most point -to -
ELEMENTARY ELECTRONICS/July-August 1978
point marker transmissions are used in
connection with overseas telephone services, it pays to DX during what are
normal business hours in DX countries.
For listeners in North America, this
means that it's often productive to tune
for European and African stations from
the listener's local sunrise to early afternoon, with frequencies above 11 MHz
offering best reception. There's another
good period from approximately 0500
to 0700 GMT on the lower frequencies,
as many European and African stations
test and adjust their equipment prior to
beginning their daily operations. For
Asian and Pacific stations, a good time
to tune is from late afternoon to approximately 0700 GMT on the higher
frequencies. Activities after 0700 GMT
usually shifts to the lower frequencies
and continues until sunrise at the DXers's location, when it becomes time to
DX the Europeans and Africans again.
We have included a list of some
point-to-point utility stations. Include the
date, frequency, and time in GMT. If
you're not one of those lucky SWLs
with direct -frequency readout receiver,
estimate the frequency to the best of
your ability. The only item you need
to quote to prove your reception is the
text of the marker itself. If some language other than English is used on the
marker as well, indicate the language.
65
DXING OUT OF BOUNDS
It's not necessary to translate any other
language you hear, as the text of the
English marker is usually identical to
the foreign language marker. Include
information on any interference and
fading you may encounter. But it's better to describe reception quality in plain
English, avoiding various reporting
codes like SINPO and SINFO. It's also
wise to avoid SWL and ham lingo like
"QTH," "73," etc. Don't ask for a QSL
-request a card or letter verifying your
reception. It helps to enclose return
postage in the form of several International Reply Coupons (IRCs), available
from your local post office.
You can often mail your reports to
the organization named in the marker
transmission. For example, you may
hear a marker transmission like this:
"This is a test transmission for circuit
adjustment purposes from a station of
Cable and Wireless, Limited, located at
St. Georges, Bermuda.' You could then
address your report to the station manager, or chief engineer for overseas telephone circuits, Cable and Wireless,
Ltd., St. Georges, Bermuda.
But sometimes you'll run into markers that don't contain sufficient information to allow you to address your report
properly. A big help here is the
SPEEDX Utility Guide, which has addresses and QSL information for numerous utility stations.
If you get deeply involved in pointto-point DXing, you may want to join
a SWL club that features coverage of
such stations. The largest such cover-
POINT-TO-POINT UTILITIES RECENTLY HEARD
Here are some recent point-to-point receptions
reported by members of SPEEDX. Catches are
listed by frequency in kiloHertz, followed by
country, name of organization transmitting the
marker, city where the point-to-point station is
located, male or female speaker, languages used,
and time of reception in GMT. All transmissions
are, in SSB unless otherwise indicated.
5307
Guinea. Post, Telegraph, and Telephone,
Conakry. Female in English and French,
0800.
5311
Saudi Arabia. Saudi Arabian Post, Telephone, and Telegraph, Jeddah. Male in
English and Arabic, 2125.
5388
Belize. Cable and Wireless, Ltd., Belize
City. Male in English 0145.
5813
Central African Republic. France Cables
et Radio, Bangui. Female in English and
French, 0515.
6598
Cuba. All American Cables and Radio,
Guantanamo Bay. Male in English, 0025.
6792
Martinique. French Telecommunications
Service, Fort de France. Female in
French and English, 0225.
6955
Cuba. All American Cables and Radio,
Guantanamo Bay. Male in English, 0150.
7350
Mexico. Mexican Post, Telephone, and
Telegraph, Mexico City. Female in Spanish, 0440.
7494
Mauritania. Office de Postes et Telecommunications, Nouakchott. Male in
French. and Arabic, 2330.
7560
Senegal. Telesenegal, Dakar. Female in
French and English, 0020.
7665
Costa Rica. Radiografica Costarricense,
San Jose. Female in English and Spanish,
AM, 0020.
7688
Congo. France Cables et Radio, Brazzaville. Female in French, 0145.
7850
Ivory Coast. Telecommunications Internationale de la Cote d'Ivoire, Female in
English and French, 2200.
Bermuda. Cable and Wireless, St.
8105
Georges. Male in English, 0330.
8740
England. Post Office Telecommunications, London. Male in English, 1550.
8751
France. St. Lys Radio, St. Lys. Female in
9052
66
French 1745.
Tahiti. French Telecommunications Ser-
9970
10250
10300
10415
10535
10784
11612
12025
12175
13140
13158
13161
13505
13740
14355
14520
14605
vice, Papeete. Female in English and
French, 0900.
Gambia. Cable and Wireless, Bathurst.
Male in English, 0000.
Argentina. Empresa Nacional de Telecomunicaciones, Buenos Aires. Female
in Spanish, 0000.
Holland. Posts, Telephone, and Telegraph, Kootwijk. Male in English, 1845.
Paraguay. Administracion Nacional de
Telecommunicaciones, Asuncion. Female
in English and Spanish, 0100.
New Caledonia. French Telecommunications Service, Noumea. Female in English and French, 2300
Cuba. International Radiotelephone Service, Havana. Female in Spanish, 1630.
Greenland. Gronlands Tekniske Organisation, Godthaab. Female in English and
Danish, 1830.
Afars and Issas. French Telecommunications Service, Djibouti. Female in English and French, 1700.
Iceland. Post and Telegraph Communications Centre, Reykjavik. Male in English, 2230.
Iraq. Posts, Telephone and Telegraph,
Bagdad. Female in English and Arabic,
1330.
Italy. Roma Radio IAR, Rome. Male in
Italian, 2000.
Italy. Genova Radio ICB, Genova. Male
in Italian, 1920.
Bermuda.
Cable and Wireless,
St.
Georges. Male in English, 1605.
People's Republic of China. Shanghai
International Communications Station,
Shanghai. Chinese, English, and French
by female speaker with instrumental
version of national anthem, "The East
is Red," 0955.
Hong Kong. Cable and Wireless, Ltd.,
Cape d'Aguilar. Female in English, 0500.
People's Republic of China. Peking International Communications Station,
Peking. Female in English, Chinese, and
French, 0950.
Brazil. Empressa Brasileira de Telecomunicacoes, Rio de Janeiro. Male in English, Fench, and Portugese 0125.
age is given by SPEEDX (Society to
Preserve Engrossing Enjoyment of DXing), P.O. Box E, Elsinore, California
92330. A sample copy of their monthly
bulletin is $1.00. You can also get information on the previously -mentioned
SPEEDX Utility Guide from that address. Another source of informative
books on point-to-point utilities is Gil fer Associates, Box 239, Park Ridge,
N.J. 07656.
That's all -now enjoy! But if you
should hear something besides a marker
transmission over a point-to-point utility, don't include it in your reception
report. In fact, don't repeat it to anybody. Under international law, all pointto-point transmissions, except for tests
or emergency broadcasts, are supposed
to be kept confidential. Fortunately for
DXers, markers fall under the category
of tests.
u
14890
15455
15490
15575
15675
16095
17600
18090
18862
19587
19837
20535
20805
20992
WHERE
France. French Telecommunications Service, Paris. Male in English and French,
1545.
Guyana. Cable and Wireless,
Ltd.,
Georgetown. Male in English, AM, 2115.
Argentina. Centro Internacional, Buenos
Aires. Female in Spanish, 1200.
Venezuela. Compania Anomia Nacional
de Telefonos, Caracas. Female in English and Spanish, 1715.
American Samoa. Government of American Samoa, Pago Pago. Male in English,
1745.
Reunion. French Telecommunications
Service, St. Denis. Female in French and
English, 1930.
India. International Overseas Telephone
Service, New Delhi. Male in English,
0850.
Upper Volta. France Cables et Radio,
Ouagadougou. Female in French and
English, 1300/
Hong Kong. Cable and Wireless, Ltd.,
Cape d'Aguilar. Female in English, 0930.
Uruguay. Usinas y Telefonos del Estado,
Montevideo. Female in English and Spanish, 1820.
Ghana.
External Telecommunications
Service, Accra. Female in English and
French, 1310.
India. International Overseas Telecommunication Service, peona. Female in
English and Hindi, 1420.
Kuwait. Posts, Telephone, and Telegraph, Kuwait. Female in English and
Arabic with Arabic music, 1045.
Vietnam. Posts, Telephone, and Telegraph, Hanoi. Male in English, 0859.
TO
5005-5454
5730-5950
6765-7000
7300-8195
TUNE
kHz
kHz
kHz
kHz
9040-9500 kHz
9775-9995 kHz
10100-11175 kHz
11400-11700 kHz
FOR
POINT-TO-POINT
DX
13360-14000
14350.14990
15450-16460
17360-17700
18030-19990
20010-21000
21750-21850
22720-23200
kHz
kHz
kHz
kHz
kHz
kHz
kHz
kHz
11975-12330 kHz
ELEMENTARY ELECTRONICS"July-August 1978
e/e assembles the...
Keymemo
KM -816
Telephone
Dialer
Give yourself a photographic
phone number memory
CIRCLE 62 ON READER SERVICE COUPON
First it was computerized toys and
games. Then, computerized auto electrical systems. Now it's a computerized
telephone dialer called the Keymemo
KM -816, which eliminates all the hassles of dirty heads, tape dropouts and
worn gear trains common to telephone
dialers which use loops of magnetic
tape.
If you need an automatic telephone
dialer, now you can get one and be
certain it will work every time. True,
you lose the excitement of wondering
whether a call to your home five blocks
away will wind up in some stranger's
home on the other side of the country,
but you gain the advantage of error free connections.
The KM -816 features several other
important convenience advantages in
addition to error -free dialing, and we'll
get to them all. First, let's start at the
beginning.
The KM -816 computerized telephone
dialer measures 65/s -in. wide x 81/2 -in.
deep x 21/4 -in. (nominal) high; it takes
up approximately as much desk or table
space as a standard telephone. It can
store up to fifteen "permanent" telephone numbers in memory and has a
temporary memory that permits instant automatic re -dialing when you
get a busy signal. It cán originate the
dialing with a speaker monitoring the
line so you know when to pick up your
own telephone's handset (or you can
originate the call by lifting the handset
first). Most important, it permits instant reprogramming of any memory
through a touch-tone type keyboard
(same arrangement and alpha-numerics
as found on standard touch-tone phones
(-0 through 9 with * and #) .
The system is line powered through
an AC adaptor that plugs into the rear
of the dialer. The adaptor also serves
to simultaneously charge a built-in
NiCad battery which can hold the
memory programming for 24 -hours in
the event of either a powerline failure
or an accidental (or intentional) disconnect from the powerline. Though
the NiCad battery preserves the programming, it does not provide automatic dialer operation. If the powerline
fails you must dial the phone just as
you always did.
Thanks For The Memory. The
memories can be programmed for any
standard number of digits used in the
U.S. for local or long distance dialing.
You may also program it to automatically provide "dial 9" and the access pause required by PABX systems
-that's where you dial 9, wait for an
"outside dialtone" and then dial the
number you want. In short, you can
put all dialing information into the
KM -816 so it will provide complete
dialing at the touch of a button without need to lift the phone's handset
even to provide the "dial 9" needed to
get an outside line through a PABX
system.
The dialer provides a 30 -second
time-out for ringing. If the telephone
automatically dialed through the dialer
does not answer within approximately
30 -seconds the dialer automatically
breaks the connection (disconnects).
If you want an extended ring (more
than 30- seconds) you simply press a
button labled "ET."
In some areas the phone system
might not be able to accept the fast dial
pulses from the dialer. If this occurs,
the. user presses a button marked "AP"
to provide a pause for dialtone before
the dialer outputs its pulses. The AP
button also provides the pause needed
ELEMENTARY ELECTRONICS July -August 1978
for "dial 9" PABX systems-it is programmed into the memory along with
the telephone number.
Connecting To The Line. Only three
connections are required-two to the
telephone line and one to the telephone
itself. Actually, one dialer connection
is made to red along with the red lead
from the phone; the remaining wires
interrupt the normal green telephone
wire. The KM -16 comes with a special
interrupt 4 -prong male/female adaptor
jack that provides the interrupt wiring.
You simply plug the KM -16's adaptor
into your telephone's jack, and then
plug the phone into the adaptor. That's
all there is to the installation. If you
don't already have a telephone jack
installed on your telephone circuit,
your local phone company will provide
one at nominal cost-or you can substitute a Radio Shack add-on jack for
the cover of the terminal block to
which your telephone's cable is attached. If your phone uses the new
miniature modular jack then similar
adaptors, and converters, are needed.
These are available at local electronic
parts and telephone accessory stores.
Testing 1...2...3. With modern
telephone equipment the most difficult
part of the whole operation is insuring
an easy and secure, and most important,
accurate programming. You don't want
your first attempt to be a wrong number 3000 miles away. You know what
it's like to get credit when the phone
company goofs on a long distance call;
imagine what it's like if it's your goof.
Fortunately, the KM -816 is almost
goof -proof.
Three LED status lights tell you
what's going on. The CALL lamp indicates the dialer is pulsing out, but not
necessarily to the line. A small safety
67
KEYMEMO KM -816 DIALER
switch on the rear allows the owner to
disconnect the dialer from the line so
unauthorized users cannot dial outthe dialer goes through the motions,
even to the extent of flashing the
CALL lamp, but no phone is actually
dialed.
A DATA lamp indicates if a
memory is programmed. It always goes
on when dialing if a number is actually in the memory. Similarly, the
DATA lamp goes on as you program
the memory. When the DATA lamp is
out it shows the memory has been
erased and is ready to be programmed.
A PROG (program) lamp indicates
the memory is ready for programming.
In order to prevent accidental erasure of a program, two separate keys
must be depressed to erase a memory.
Similarly, two keys must be depressed
to program a memory. In this manner,
accidental erasures and programming
caused by someone fooling with the
keyboard are made difficult, if not
almost impossible. Also, buttons must
be keyed in a certain sequence for
programming, almost entirely eliminating the possibility of someone programming a number "as a gag, or
joke." (Also, the "secret" switch in
the back allows busy hands and jokesters to fool with the device while preventing them from actually dialing out.)
Overall, the Keymemo KM -816
proved easy to program, accurate, and
secure. In the presence of transient
There are 16 memories; 15 are permanent
and are provided with a name slot and
paper tab. The 16th is labeled Free Dialing
and is a temporary memory. It allows a
number to be redialed when busy simply
by touching this key. A speaker monitors
the line so you can hear when the party on
the other end answers. You can also use
the dialer with the phone off the hook. The
speaker is simply a hands-off monitor for
calls. The Keymemo KM -816 dialer takes
up just about as much space as a normal
telephone. Circle No. 62 on the reader
service coupon for more information.
The AC adaptor plugs into a socket on the rear of the dialer. The small miniature switch
to the right of the power socket disconnects the dialer from the line while still allowing
the dialer to go through all the motions, just as if it's actually dialing a number. This foils
would-be pranksters.
Removing the cover (left) displays the guts of the Keymemo Dialer. On the lower right is
the NiCad battery which will keep the memory alive even if the power is off for 24 hours.
The battery charges automatically. The computer and memories are above the battery.
The speaker and switching matrices are mounted on the inside of the cover.
68
powerline pulses, and radio frequency
fields (from a nearby transmitter), the
KM -816 held its programming, it
neither lost all nor part of its programming, or dialed false numbers.
Overall, an excellent dialer.
Kit? The model we received was a
semi -kit priced at $129.95. All the difficult assembld was done at the factory, and the kit really consisted of
mounting two PC boards, plugging together the interconnecting wires, and
installing the monitor speaker and output cables. There are no user adjustments. The whole bit should take less
than one hour.
The KM -816 is also available completely assembled for $220.95. Check
with your local telephone equipment
store.
The KM -816 complies with Part 68
of the FCC rules and regulations No.
AH 297E -62837 -DI -R. It has a ringer
equivalence of 0.0 B; meaning it takes
no ringer power (because it's a dialer,
and there is no ringer).
For more information write to Chung
Long Electronics Corp., Box 18732,
Seattle, WA 98118, or circle No. 62 on
the reader's service coupon.
ELEMENTARY ELECTRONICS/July-August 1978
PUTER READOUT
by Norman Myers, Computers Editor
Choose this tricky computer for challenging chess
What you are going to read here
could not have been written only five
years ago. It would not have been possible. We are going to talk about one of
the most challenging applications that
a computer-especially a microcomputer
-can have. We will talk about computers playing chess. Some feel this is
a breakpoint of computer development.
After jumping through a little history,
we will see what is happening with
large computers as they attempt to beat
chess masters. Then we will explore a
chess -playing computer you can buy
(and a checkers computer, in case you
prefer that) and we will go into the
fascinating micro -computer programming that makes it work: And work it
does-it beats good chess players and
can be used as an excellent trainer to
improve your chess. Only five years ago
the thought of such a microcomputer
game was but a dream.
Artificial Intelligence. Chess on computers dates back almost twenty years.
Most universities had someone interested in writing a good program. If a
computer could play chess, it was felt,
the same programming techniques
would allow computers to make fairly
rapid and proper decisions in, many
other areas. The thought that superhuman brain power could be programmed for decision making-like
what stock 'to buy and when, or what
warehouse items to order, when, and
in what volumes-was the driving force.
It was a correct line to follow because,
while a perfect super -brain program is
not yet here, those working in the field
of artificial intelligence feel we are presently closer than ever and that progress
is being made every month. They claim
that someday a person will be able to
sit at a console, ask any question and
get intelligent answers so realistic that
the person will not be able to tell if a
human or a computer is giving the answers. This is the ultimate test of artificial intelligence.
An historic test of computer "intelligence" is happening even as you read
this article. "Chess 5"-probably the
most powerful computer chess -program
ELEMENTARY ELECTRONICS/July-August
in the world is being developed at
Northwestern University in Evanston,
Illinois. That program will pit wits
against one of the best chess players in
the world, David Levy of Great Britain.
Northwestern University has had the
edge in computer chess programs for
several years. The last version, called
Chess 4.6, has been used in several tournaments against good chess amateurs
and has always been victorious. In 1976
it beat over 100 good players in a west
coast tournament and in 1977 it entered a tough Minnesota Tournament
and emerged not only a total victor but
also ä winner of the coveted title of
chess master. But, there is more. The
popular story in chess circles goes that,
in the International Computer Chess
Tournament held last year in Toronto,
the Chess 4.6 program emerged victorious by defeating the Russian computer
program four games out of four.
How does a strong chess master fare
against the 4.6 program? Well, David
Levy beats the 4.6 most of the time. But
the brains behind 4.6, a chess -loving
computer science whiz at Northwestern,
is developing the Chess 5 program that
may be able to beat David Levy. It is an
historic time. If the computer is able to
show the subtle strategy, the adaptability to changes in the opponent's strategy, and the ability to look five and six
moves ahead, then a new era in com-
puter
development will have been
achieved. Further, if the Chess 5 beats
David Levy, reports say he will lose a
friendly but expensive wager made some
years ago with chess -playing colleagues
that a computer could not beat him.
The Chess 5 program is run on a
large and powerful computer made by
Control Data Corporation. There are
gobs of memory and lots of processor
power in registers, arithmetic units, instruction sets, counters, and complex
control units that allow simultaneous
events to be performed. This computer
with its tape drives, control console,
memory units, and processor will not
fit in a standard living room. It can
perform tens of thousands of operations
each second and has enough memory
to handle dozens upon dozens of special
program routines that can give it that
extra quality of making subtle chess
moves.
Chess in a Micro. Now how does a
chess -playing microcomputer stack up
against something as powerful as Chess
5? Or, look at it this way; how does a
computer that takes up less space than
a breadboard measure up to one that
cannot fit in the kitchen? Well, I don't
know the answer, but I do know this:
Fidelity Electronics at 5245 W. Diversity Avenue, Chicago, Ill. 60639
makes a breadboard -sized chess -playing
computer that whips the pants off me,
The Chess Challenger from Fidelity Electronics is a chess-playing whiz ready for a game
whenever you are. Beginner or pro, it suits its style to you. Circle number 50 for info.
1978
69
Wg
COMPUTER READOUT
and I was considered to be a good
chess player in my college days. Fidelity
actually makes two units, one is the
Basic Chess Challenger and the other is
the Advanced Chess Challenger, which
has three levels of play that you can
select from. The basic unit sells for
around $150 and the advanced for
around $200. We will get into the differences between the two shortly, but
when I say the Challenger beats me, I
mean the advanced unit on level three
(the top level), and sometimes on level
two. And by the way, I have loaned
the unit to five good players with the
result that four find it hard to beat and
one-a chess master who once played
Olympic chess-found it beatable because he is able to look ahead more
moves than the computer is programmed to do. I understand there is a
chess microcomputer made by Applied
Concepts in Texas that has different
levels of play but I was not able to try
it out.
Hardware First. Before getting into
the software concepts behind this
Fidelity masterpiece, let us look at the
hardware in the basic and advanced
units. First, both units come in a walnut
case with a plastic top that has a chess
board with numbered rows across and
lettered columns. Each square therefore
has its own letter/number identifying
combination. The keyboard allows you
to enter your move by specifying the
"from" and "to" positions via a letter
and a number. The keys are the soft touch kind so you just touch the plastic
to activate a key. An LED readout
shows your entry and shows the computer's choices for moves. The unit is
not portable since it requires a house
electrical outlet. The basic and advanced Challengers use the popular
Intel 8080 microprocessor and 512
bytes (8 bits per byte) of random access memory on four integrated circuits. The random access memory is
used by the processor as a kind of
scratch pad for trying and evaluating
different moves. The program itself is
permanently stored in a 2048 byte read
only memory for the basic unit, and
4096 byte memory for the advanced
unit. This ROM is on a single chip that
has been specially masked with the
Fidelity chess program. The rest of the
Challenger hardware includes a 555
timer integrated circuit for debouncing
the keys, power supply circuitry including a voltage regulator, and segment
driver integrated circuits for the LEDs.
70
Software Smartware. In most of our
past articles on microcomputer applications we discussed hardware and architecture layout with some mention of the
program basics. This time we will get
into the program basics in much more
detail because that is where the heart
of this intelligent chess playing box
rests. We will not get into actual program code-that would be nothing but
a mess of details. We will get into the
basic concepts of how the computer
plays chess. You do not have to know
chess to understand the principles dis -
CHESS
CHALLENGER
ELcCToN.c
criEctc
LOSE
PROM
TO
II ID
11111
ill III III II
111111111111
Data on moves is input/output via a keyboard. The computer communicates with
human players using the algebraic style of
chess notation-a system easily learned.
cussed here. These basics have been
used in other computer chess programs
but remember that we are dealing here
with limited computer memory and a
comparatively simple processor-so the
programmer has to be especially careful
and clever. The Fidelity program was
written by Ron Nelson who is now
developing other computer games for
Fidelity.
In terms of program desigt, the basic
unit can be viewed as the same as the
advanced unit operating on level one
except that the advanced unit on level
one is able to do some extra things, like
controlling the center squares of the
board. Because of this similarity, we
will discuss only the advanced unit here.
We will assume that you are playing
white (you move first) and that the
computer is playing black, although you
can actually choose which color you
want. Further, if you want the computer to take white, you can tell it what
opening move you want it to make in
order to practice one of your own
strategies. So, you have white and you
make a move. In order to make this a
general discussion, let's assume the
game has been going on for some time
so this is not just your opening move.
You enter the move via the keyboard.
The Challenger immediately flips its
memory around where it has the location of each piece and pretends it is
white. It then attempts to make the
same move you have made and checks
it against its rules. If it cannot do the
move, it knows your entry was illegal
and it tells you so via the display. If it
can make the move, it knows you made
a legal move and flips the memory back
to black in order to play its own pieces.
Now comes the fun. The processor
goes to the memory location representing the lower corner square on the
board. If a black piece is there, it will
attempt to move that piece. If the piece
is a knight, the knight -moving routine
is called in by the processor, etc. If it
can be moved, the processor forms a
temporary picture in its memory of this
new location and the location of all the
other pieces on the board. Now the
processor flips its memory to play white.
The object is to find the move that is
best for white given the move that black
just temporarily made. This is done by
going through all of white's pieces,
moving each on- in the computer memory and evaluating each new board in
memory. Let's be more specific.
Suppose the computer temporarily
moved its black knight, then found that
white could have two moves, a white
pawn or a white bishop. That gives two
temporary board layouts that have to
be evaluated. The evaluation is done
via a control matrix that assigns values
to positions of pieces on the board. A
value is obtained for each board layout.
The 16 bit capacity of the Intel 8080
system is used to assign numbers over
a range from zero to 32,000 so very
fine resolution is obtained and the
chance of a tie between two board layouts is unlikely. The evaluation is done
via a control matrix that assigns values
to positions of pieces on the board.
A value is obtained for each board
layout. The 16 bit capacity of the
Intel 8080 system is used to assign
numbers over a range from zero to
32,000 so very fine resolution is obtained and the chance of a tie between
two board layouts is unlikely. The value
for one board is compared to the value
for the previous board and the board
layout with the higher value is saved in
memory. In our example, this might
be the black knight, white pawn layout.
Having tested and evaluated all the
(Continued on page 88)
ELEMENTARY ELECTRONICS/July-August 1978
E
MS
S IN Y. U FUWREJ
Whi
of the thr-e competi g systems
ill the FCC inally deci a upon?
by
: rry L. Helms r.
cited technical problems for its refusal
to allow AM stereo. Undaunted, several
firms continued work on AM stereo
systems, and one system was actually
used for regular broadcasts by station
XETRA, 690 kHz, in Tijuana, Mexico,
during 1970! The technical difficulties
that caused the 1961 rejection of AM
stereo were gradually resolved, leading
the FCC to formally propose the establishment of AM stereo on July 6, 1977,
in docket 21313. Insiders in the broadcasting industry agree that AM stereo
is inevitable-only the decision as to
which method will be used to transmit
and receive AM stereo is left for the
FCC to decide.
Why AM Stereo? It's difficult to believe that FM broadcasting was once an
industries are currently on the brink of
a revolution. Within a few months,
the Federal Communications Commission (FCC) will almost certainly give
the go-ahead for AM broadcast stations
to begin operations in full stereo, placing them on better competitive footing
with FM broadcasters and opening a
new spectrum of possibilities for both
audiophiles and DXers. The technology
for AM stereo already exists-in fact,
test broadcasts have already been conducted in the United States!
The concept of AM stereo is not a
new idea. In 1958 the FCC was petitioned to allow AM stereo broadcasting, but refused to do so in an order
released on October 2, 1961. The FCC
THE AUDIO AND BROADCASTING
AM
TRANSMITTER
L+ R
SIGNAL
LEFT CHANNEL
RIGHT CHANNEL
MATRIX
CIRCUIT
L
R
SIGNAL
FREQUENCY
MODUL ATOR
The Belar System begins like the Magnavox in that matrix circuitry produces sum and difference signals from the two channel inputs. The sum signal is conventially amplitude
modulated while the difference frequency is applied to a frequency modulator. Both the
outputs from the AM modulator and Frequency modulator are fed, in combination, to an
AM transmitter. The combined AM/FM signal is then transmitted as an AM signal, in the
usual way. Separate AM and FM detectors and matrix circuit must be used in Belar receiver.
ELEMENTARY ELECTRONICS/July-August 1978
economic disaster area when one observes the huge market for FM receivers and tuners that exists today. But in
the 1950's FM was at an extreme competitive disadvantage to AM. Stereo
broadcasts for FM were authorized in
April, 1961 and one of the reasons
given by the FCC for FM stereo was
that it could help FM broadcasters compete more effectively with their AM
brethern. But, in subsequent years, the
entire audio industry has shifted to
stereo, and even quadraphonic sound,
while AM radio has remained a monophonic medium. Many in the broadcasting industry now feel that FM is a
more economically successful medium
than AM due to the stereo advantage.
It is widely felt that only the introduction of AM stereo can restore competitive balance between the two.
The widespread support for AM
stereo is demonstrated by the composition of The National AM Stereophonic
Radio Committee, one of the prime
movers behind the drive for AM stereo.
Included in the Committee's membership are the Institute of Electrical and
Electronics Engineers, the Electronics
Industries Association, the National As- sociation of Broadcasters, and the National Radio Broadcasters Association.
The Committee arranged for on -the -air
tests of three stereo AM systems during
August, 1977 and submitted the results
to the FCC in reply to Docket 21313.
Individual broadcasters are also anxious
to begin AM stereo service.
"When the FCC approves a system,
WBT is planning to broadcast in AM
stereo on a full-time basis," says Rich 71
I»
FUTURE OF AM STEREO
LEFT CHANNEL
SUMMING
NETWORK
BALANCED
MODULATOR
and Mertz, technical operations man-
ager for station WBT in Charlotte,
North Carolina. WBT was one of the
stations that conducted AM stereo tests
in August, 1977.
How AM Stereo Works. There are
four basic systems for AM stereo competing for the FCC's approval. All four,
like FM stereo, make use of two separate channels commonly referred to as
the left and right channels. Beyond
that, however, the four systems differ
significantly from each other. The various methods are not compatible with
the others; only one will be selected
by the FCC for use.
The oldest system for AM stereo is
known as the Kahn system, developed
by Kahn Communications, Inc. Kahn
was one of those who petitioned the
FCC for AM stereo back in 1958. Although the petition was denied, Kahn
continued work on their system, eventually leading to full-time use of it over
station XETRA in Mexico, as mentioned earlier. While located in and
licensed to operate in Mexico, XETRA
puts a potent signal into the San Diego,
California area and programs almost
entirely in English for the San Diego
market. Mexican broadcasting regulations are somewhat more flexible than
those in the United States, and in 1970
permission was granted for XETRA to
use the Kahn system for its regular
broadcasts.
A regular AM signal consists of a
carrier frequency and two identical
sidebands on either side of the carrier
frequency. Thus, for XETRA's 690
kHz frequency, its carrier was on 690
with two 3 kHz wide sidebands on 687690 kHz and from 690-693 kHz. In
simplified form, the Kahn system put
one stereo channel on the lower frequency sideband and the other stereo
channel on the upper frequency side band. This system made it possible to
receive AM stereo broadcasts by using
two ordinary AM receivers. One receiver was tuned to XETRA's upper
sideband while a second receiver was
tuned to the lower sideband. All other
stereo AM systems require receivers
designed specifically for stereo reception. Proponents of the Kahn system
have stressed this availability of AM
stereo using conventional equipment in
their proposals to the FCC.
The XETRA experiment was eventually discontinued. The FCC allowed
Kahn to conduct tests of its system over
station WFBR, Baltimore, Maryland
72
SUMMING NETWORK ADDS OUTPUT
OF THE BALANCED MODULATORS
TO CARRIER FREQUENCY; RF
AMPLIFIER AMPLIFIES SIGNAL
AND FEEDS TO ANTENNA SYSTEM
CARRIER
FREQUENCY
OSCILLATOR
RIGHT CHANNEL
SUMMING
NETWORK
BALANCED
MODULATOR
Stereo's two channels, using the Magnavox system, are first converted by matrix circuitry into two new signals; one the sum of the left and right channel frequencies and the
other being the difference between those frequencies. The difference (L-R) frequency is
AM modulated while the sum frequency (L 1-R) is phase modulated. A nice touch is a tone
generator which adds a subaudible, 5 Hz tone to the phase modulation. A receiver may be
designed with a stereo indicator lamp which will light up whenever the tone is received.
AM
MODULATOR
L -R
SIGNAL
LEFT CHANNEL
RIGHT CHANNEL
MATRIX
CIRCUITRY
AM
TRANSMITTER
L+ R
SIGNAL
PHASE
MODULATOR
(TONE GENERATOR)
The Motorola idea is to use dual summing networks and balanced modulators in order
to separately modulate two carriers at the same frequency but at different phases. The
carrier frequency oscillator is used to set the transmitter frequency. Output from the
balanced modulators is combined with that of the carrier frequency oscillator's in a
summing network and is then fed to a RF power amplifier. A system on the Motorola principle must use phase detection and balanced modulators, but avoids the use of matrices.
during 1975. Yet despite Kahn's head
start, most observers feel that it is highly
unlikely ,that the Kahn system will be
adopted by the FCC. More recent systems offer the potential for better fidelity and stereo quality than the Kahn
system. Perhaps significantly, the National AM Stereophonic Radio Committee omitted the Kahn system from
the series of AM stereo tests it conducted in 1977.
The AM stereo system that the FCC
eventually selects will almost certainly
be either the Magnavox, Motorola, or
Belar System. The Magnovox and Belar
systems use a combination of amplitude
and phase/frequency modulation while
the Motorola system uses phase differences between two signals to transmit
both stereo channels on the same carrier
wave. Stereo signals transmitted by all
three methods can be received in mono
ELEMENTARY ELECTRONICS/July-August 1978
on monophonic receivers without modification, while stereo reception will require receivers designed for stereo AM.
The Magnavox system uses a matrix
circuit to convert the two channels into
two new signals, one the sum of the
frequencies of the left and right channels with the other the difference in
frequency between left and right. The
difference (L-R) frequency is AM
modulated in the conventional manner
while the sum (L+R) frequency is fed
to a phase modulator. The phase modulator varies the phase, or time interval,
between changes in the amplitude of
the carrier current wave. The output
of the phase modulator is fed to the
AM transmitter and transmitted with
the output of the AM modulator: An
added feature of the Magnavox system
is a tone generator which feeds a sub audible 5 Hz tone into the phase modulator. When received on a receiver designed for the Magnavox system, it
lights a stereo indicator lamp similar to
those found on FM stereo tuners. This
is the only system with such a stereo
identification provision and it is a
strong point in favor of it. A receiver
for the Magnavox system uses both AM
and phase modulated detectors to recover the stereo transmissions.
The Belar system was originally developed by RCA, although RCA is no
longer actively involved in the development of AM stereo systems. Like the
Magnavox system, the Belar method
uses a matrix circuit to produce sum
and difference signals from the two
channel inputs. The sum signal is amplitude modulated in a conventional
manner while the difference frequency
is applied to a frequency modulator.
The output of the frequency modulator
is fed to a conventional AM transmitter
along with the output of the amplitude
modulator. The combined AM/FM signal is then transmitted as an AM signal
in the usual manner. A Belar system
receiver uses separate AM and FM
detectors and a matrix circuit to reproduce the two channels.
The stereo AM system developed by
Motorola uses summing networks and
balanced modulators to separately
modulate two cartiers at the same frequency but in different phases. The
transmitter frequency is determined by
a carrier frequency oscillator. The output of the balanced modulators is combined with the carrier frequency oscillator output in a summing network
circuit and then fed into a RF power
amplifier. A Motorola system receiver
uses phase detection and balanced
modulators to recover the two stereo
channels. An advantage of this system
is that it avoids the use of matrix circuits.
The Tests. The National AM Stereophonic Radio Committee has established a receiving site and laboratory in
Whose system will the
FCC decide upon for
AM stereo? Will it be
Belar, Motorola, Magnavox-or some other
system entirely? It's a
close race. The best
info to date is contained in the report,
"AM Stereo" from the
Electronics Industries
Association. See the
text on how to order.
The National
AM Stereophonic
Radio Committee
ELEMENTARY ELECTRONICS July -August 1978
Bethesda, Maryland for the purpose of
evaluating tests of the three AM stereo
systems. The first tests were conducted
over WGMS, 570 kHz,. in Bethesda,
Md., from August 7 to 10, 1977. The
tests were conducted from midnight to
5:00 a.m., local time. The next series
ran from August 11 through 15 over
WTOP, 1500 kHz, in Washington, D.C.
The potentially most significant tests
were conducted over WBT, 1110 kHz,
in Charlotte. N.C., on August 21. The
tests were run from midnight to 5:00
a.m. WBT is a 50 -kilowatt clear-channel
outlet whose nighttime coverage is from
Cuba to the Canadian Maritimes and
provided an ideal test for the effects of
skywave propagation on AM stereo signals. It is widely believed that the system that performs best as far as skywave propagation is concerned will be
the one accepted by the FCC.
In January of 1978, the National
AM Stereophonic Radio Committee
submitted the results of its August,
1977 tests to the Federal Communications Commission. The Motorola system
performed best in the transmission of
skywave signals as well as in very noisy
environments. The Belar system was
found to be the simplest overall, as well
as providing the best compatibility with
existing monophonic AM receivers. The
report did not recommend any of the
competing systems, however.
Some manufacturers are already getting into the AM stereo act. National
Semiconductor Corporation has begun
work on developing integrated circuit
chips for demodulating AM stereo signals. Sources in the electronics industry
estimate that AM stereo could generate
wholesale business of $250 million per
year after its introduction, with about
80% of it in car radio equipment.
If you'd like to delve deeper into the
highs and lows of AM stereo you could
send for the AM Stereo Report from
the Electronic Industries Association.
The 500 -plus page, spiral -bound book
is available for $20.00 from: AM Stereo
Report, Electronic Industries Association, 2001 Eye St., N.W., Washington,
D.C. 20006.
Effects of AM Stereo. The introduction of AM stereo will have several
effects on broadcasters, equipment
manufacturers, and DXers. Broadcasters will likely have to upgrade their
studio to transmitter link equipment, as
most such links are today handled by
telephone lines having virtually no response over 5 kHz. Considering that
most AM tuners today cannot reproduce frequencies above 5 kHz, such a
limitation poses no problem for monophonic transmission. Yet AM stereo
(Continued on page 90)
73
checks out the...
EV Game 500
Wan&10 cure those CB rip-off blues?
JuSt put one of these disappearing
/An/FPM antennas on the family car
CIRCLE 75 PN READER SERVICE COUPON
One of the most popular and successful defenses against a ripoff of your
mobile CB is a disappearing antenna.
Without an antenna or its mount to
announce the presence of a CB transceiver somewhere in your vehicle it's
odds-on no one will know you have
one. Unfortunately, many of the socalled disappearing CB antennas which
telescope through a motor drive into
the trunk or fender well leave some
part of the antenna or loading coil
sticking out to announce that it is something more than a standard disappearing AM/FM antenna (they telescope
completely out of sight). Fact is, those
itty-bitty stubs are often a magnet for
vandals who try to see if they can pull
the antenna to its full height.
But there is one disappearing CB antenna that truly vanishes from sight
when not in use-the EV-Game Model
500 Fully Automatic Antenna. Fully
collapsed, no part of the antenna itself
or its CB loading coil is exposed to
busy little hands. The whole thing
really looks like an ordinary disappearing AM/FM antenna that's been collapsed into the trunk or fender.
The Model 500 antenna is driven by
a vertically oriented motor at the base
that permits the antenna to be installed
on or in the cowl or fender well of
many cars, in addition to the more
common trunk installation. Fully extended it's a 40 -inch center loaded
CB/AM/FM antenna. That's right, a
three-way threat. Through the use of
a supplied coupler the CB antenna also
serves an AM or AM/FM radio without interaction between the radio and
the CB.
At the very tip of the antenna is a
(Continued on page 89)
.
The EV Game 500 CB/FM/AM disappearing antenna retracts completely out of sight into its retractor well.
3WR matching
CB
RADIO
ELECTRONIC RELAY BOX
BROWN
COUPLER
PL -259
Antenna Cable
1300m/m
Gray mark
-hI
1500m/m
-
4800m/m
T
1100m/m
EXTENSION POWER WIRE HARNESS
250m/m
GREEN
A coupler mates the antenna to both your CB 'set and
your AM/FM radio. The antenna retracts automatically
when the ignition is shut off. For more information circle
No. 75 on the readers service coupon or write to EV
Game Inc., 186 Buffalo Avenue, Freeport, N.Y. 11520.
74
gnition Terminal
BATTERY
ELEMENTARY ELECTRONICS/July-August 1978
MICROPROCESSORS
THEIR NUMBER SYSTEMS
AND CODES
Microprocessors are changing your world, and if you want to keep pace you'll have to
know how they work and how to use them. This two part series will have you understanding the basics of using number systems and codes-the essentials of microprocessor
programming-and give you the foundation for experimenting on your own. Get ready for
the great new microprocessor era with ELEMENTARY ELECTRONICS.
Heath Catalog
Condensed and modified for magazine publication, by permission, from pp. 1-1 to 1-61, in the Heath Microprocessor Course,
MI 49022.
number EE -3401. Copyright 1977, all rights reserved. Microprocessor Course is available from Heath Company, Benton Harbor,
WILL LEARN. In this second installment of
the Heathkit home -study course on microprocessors
you will be introduced to a number of new, useful concepts.
You'll be brought one step closer to a full understanding of
microprocessors.
You will first learn all about hexadecimal numbers. You
will be able to evaluate their decimal equivalents and then
convert back from decimal to hexadecimal.
Then, you'll learn to convert back and forth between the
binary and hexadecimal systems. You'll comprehend why
hexadecimal numbers are so important to understand if you
intend to work with binary-based circuitry.
Finally, you'll learn a bit about binary codes. Here you
will find the secret of the binary coded decimal and how
to convert between that code and the decimal system. You'll
discover the Gray code and then you'll meet the modernday ASCII code, in a few varieties, along with its ancestor
the BAUDOT code.
WHAT YOU
HEXADECIMAL NUMBER SYSTEM
Hexadecimal is another number system that is often used
with microprocessors. It is similar in value structure to the
octal number system, and thus allows easy conversion with
the binary number system. Because of this feature and the
fact that hexadecimal simplifies data entry and display to
a greater degree than octal, you will use hexadecimal more
often than any other number system in this course. As the
name implies, hexadecimal has a base (radix) of 1610. It
uses digits 0 through 9 and the letters A through F.
The letters are used because it is necessary to represent
1610 different values with a single digit for each value.
Therefore, the letters Á through F are used to represent
the number values 1010 through 1510. The following discussion will compare the decimal number system with the
hexadecimal number system.
All of the numbers are of equal value between systems
310, 910= 916, etc.). For numbers greater
(010
010, 310
B16,
A16, 1110
than 9, this relationship exists: 1010
1510
and
13100
F16.
C1ß,
1210
D16, 1410
E16,
Using letters in counting may appear awkward until you
become familiar with the system. Figure 1 illustrates the
relationship between decimal and hexadecimal integers,
while Figure 2 illustrates the relationship between decimal
and hexadecimal fractions.
=
=
=
=
=
=
ELEMENTARY ELECTRONICS /July -August 1978
=
=
DECIMAL
HEXADECIMAL
0
0
1
1
2
2
BINARY
0
1
10
3
3
11
4
4
100
5
5
101
6
110
7
6
7
8
8
1000
9
10
9
1001
A
1010
11
B
1011
12
1100
14
C
D
E
15
F
13
16
17
18
19
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
lA
1B
1C
1D
lE
111
1101
1110
1111
10000
10001
10010
10011
10100
10101
10110
10111
11000
11001
11010
11011
11100
11101
11110
11111
32
1F
20
100000
33
21
100001
34
35
22
23
100010
100011
31
Figure
1
As with the previous number systems, each digit posi-
tion of a hexadecimal number carries a positional weight
75
DECIMAL
HEXADECIMAL
0.00390625
0.0078125
0.01171875
0.015625
0.01953125
0.0234375
0.02734375
0.03125
0.03515625
0.0390625
0.04296875
0.046875
0.0507812S
0.0546875
0.05859375
0.0625
0.06640625
0.0703125
0.07421875
0.078125
0.08203125
0.0859375
0.08984375
0.09375
0.09765625
0.1015625
0.10546875
0.1093 75
0.11328125
0.1171875
0.12109375
0.125
0.01
BINARY
0.00000001
0.0000001
.0.00000011
0.000001
0.00000101
0.0000011
0.00000111
0.00001
0.00001001
0.0000101
0.00001011
0.00011
0.00001101
0.0000111
0.00001111
0.0001
0.00010001
0.0001001
0.00010011
0.000101
0.00010101
0.0001011
0.00010111
0.00011
0.00011001
0.0001101
0.00011011
0.000111
0.00011101
0.0001111
0.00011111
0.001
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.0A
0.0B
0.0C
0.0D
0.0E
0.0F
0.1
0.11
0.12
0.13
0.14
0.15
0.16
0.17
0.18
0.19
0.1A
0.1B
0.1C
0.1D
0.1E
0.1F
0.2
Figure 2
which determines the magnitude of that number. The
weight of each position is determined by some power of
the number system base (in this example, 1610). The total
quantity of a number can be evaluated by considering the
specific digits and the weights of their positions. (Refer
to Figure 3 for a condensed listing of powers of 1610.)
For example, the hexadecimal number E5D7.A3 can be
written with positional notation as follows:
(E X 163)
+ (5
X 162)
+ (D
(A X 16-')
+
X 161) + (7 X 16°)
(3 X 16-2)
+
The decimal value of the hexadecimal number E5D7.A3
is determined by multiplying each digit by its positional
weight and adding the results. As with the previous number systems, the radix (hexadecimal) point separates the
integer from the fractional part of the number.
(14
X4096)+(5
X
256)+(13
X
16)+(7
X
1)+(10
1/16) + (3 X 1/256) = 57344 + 1280 + 208 + 7 +
0.625 + 0.01171875 = 58839.6367187510
X
16-4= 1/65536
= 0.0000152587890625,,,
16-3= 1/4096= 0.00024414062510
= 0.003906251 °
16-2
=
16-'
= 1/16 = 0.062510
110 = 16°
l
/256
16,0=
25610
409610
6553610
161
= 162
= 163
= 164
104857610= 16''
167772161o= 16°
Figure 3
a base number of 1610. As an example, the decimal number 156 is converted into its hexadecimal equivalent.
156
- 16 = 9
= C LSD
9=0-MSD
with remainder 12
9= 16=0
Divide the decimal number by 16,,) and note the remainder. If the remainder exceeds 9, convert the 2 -digit
number to its hexadecimal equivalent (1210 = C in this
example). Then divide the quotient by 16 and again note
the remainder. Continue dividing until a quotient of 0
results. Then collect the remainders beginning with the
last or most significant digit (MSD) and proceed to the
first or least significant digit (LSD). The number 9C,6 =15610. NOTE: The letter H after a number is sometimes
used to indicate hexadecimal. However, this course will
always use the subscript 16.
To further illustrate this, the decimal number 47632 is
converted into its hexadecimal equivalent.
47632
2977
-
16
= 2977
_ 16 = 186
186 _ 16 = 11
11 _ 16=0
with remainder
= 0 4- LSD
=
10 = A
11 =B-MSD
0
1
1
The division process continues until a quotient of 0 results. The remainders are collected, producing the number BA1010
4763210. Remember, any remainder that
exceeds the digit 9 must be converted to its letter equivalent.
(In this example, 10
A, and 11
B.)
To convert a decimal fraction to a hexadecimal fraction,
multiply the fraction successively by 1610 (hexadecimal
base). As an example, the decimal fraction 0.78125 is converted into its hexadecimal equivalent.
=
=
=
Conversion From Decimal to Hexadecimal
0.78125 X 16 = 12.5
0.50000 X 16 = 8.0
Decimal to hexadecimal conversion is accomplished in
the same manner as decimal to binary or octal, but with
Multiply the decimal by 1610. If the product exceeds one,
subtract the integer (overflow) from the product. If the
76
= 0.5 with
=0
overflow 12
8
=C
= 8 F-
MSD
LSD
ELEMENTARY ELECTRONICS/July-August 1978
Understanding Microprocessors
!NM
"overflow" exceeds 9, convert the 2 -digit number to its
hexadecimal equivalent. Then multiply the product fraction by 16,,, and again note any overflow. Continue multiplying until an overflow, with 0 for a fraction, results. Remember, you can not always obtain 0 when you multiply
by 16. Therefore, you should only continue the conversion
to the accuracy or precision you desire. Collect the conversion overflows beginning at the radix point with the
MSD and proceed to the LSD. The number 0.C8,6 =0.7812510.
Now the decimal fraction 0.136 will be converted into
its hexadecimal equivalent with five -place precision.
0.136
0.176
0.816
0.056
0.896
X 16
X
X
X 16
X
=
2.176
= 0.176
overflow
16= 2.816=0.816
16= 13.056=0.056
= 0.896 = 0.896
= 2 -+ MSD
2=2
13=D
0= 0
The number 0.22D0E,,; approximately equals 0.13610.
If you convert 0.22D0E,0 back to decimal (using positional
notation), you will find 0.22D0E10 = 0.135999679565429687516. This example shows that extending the precision of
your conversion is of little value unless extreme accuracy
is required.
As shown in this section, conversion of an integer from
decimal to hexadecimal requires a different technique than
for conversion of a fraction. Therefore, when you convert
a hexadecimal number composed of an integer and a fraction, you must separate the integer and fraction, then perform the appropriate operation on each. After you convert
them, you must recombine the integer and fraction. For example, the decimal number 124.78125 is converted into its
hexadecimal equivalent.
124.78125,0=
124
7
- 16 = 7
= 16=0
+ 0.7812510
with remainder 12
12410
= 7C16
0.78125 X 16 = 12.5 = 0.5
0.50000 X 16 = 8.0 = 0
0.7812510 = 0.C816
= C +- LSD
7=7 «-M SD
12410
overflow 12
overflow 8
= C MSD
= 8 4-- LSD
124.7812510= 12410 + 0.7812510 =7C16
+
0.C816
X
23)+(1
X
= 7C.C816
First separate the decimal integer and fraction. Then
convert the integer and fraction to hexadecimal.
Finally, recombine the integer and fraction.
Converting Between the Hexadecimal and
Binary Number Systems
Previously, the octal number system was described as an
excellent shorthand form to express large binary quantities.
This method is very useful with many microprocessors. The
trainer used with this course uses the hexadecimal number
system to represent binary quantities. As a result, frequent
conversions from binary -to -hexadecimal are necessary. Fig
ures 1 and 2 illustrate the relationship between hexadecimal
and binary integers and fractions.
As you know, four bits of a binary number exactly equal
1610 value combinations. Therefore, you can represent a
4 -bit binary number with a 1 -digit hexadecimal number:
ELEMENTARY ELECTRONICS 'July -August 1978
22)+(0X 21)+(1
X
20)_
Because of this relationship, converting binary to hexadecimal is simple and straightforward. For example, binary
number 10110110 is converted into its hexadecimal equivalent.
101101102
REWRITE AS
LSB
MSB
0110
1011
YIELDS
2
14=E -LSD
16= 14.336=0.336
11012=(1
8+4+0+1=1310=Dla
B616
To convert a binary number to hexadecimal, first separate the number into groups containing four bits, beginning with the least significant bit. Then convert each 4 -bit
group into its hexadecimal equivalent. Don't forget to use
letter digits as required. This gives you a hexadecimal
number equal in value to the binary number.
Now convert a larger binary number (10101101101) into
its hexadecimal equivalent.
101101102
REWRITE AS
LSB
MSB
0101
0110 1101
YIELDS
56D16
Again, the binary number is separated into 4 -bit groups
beginning with the LSB. However, the third group contains only three bits. Since each group must contain four
bits, a zero must be added after the MSB. The third group
will then have four bits with no change in the value of the
binary number. Now each 4 -bit group can be converted
into its hexadecimal equivalent. Whenever you add zeros
to a binary integer, always place them to the left of the
most significant bit.
Binary fractions can also be converted to their hexadecimal equivalents using the same process, with one exception; the binary bits are separated into groups of four, beginning with the most significant bit (at the radix point).
For example, the binary fraction 0.01011011 is converted
into its hexadecimal equivalent.
0.010110112
REWRITE AS
LSB
MSB
0.0101
1011
YIELDS
0.5Bí6
the binary number into groups
must
separate
Again, you
of four, beginning with the radix point. Then convert each
4 -bit group into its hexadecimal equivalent. This gives you
a hexadecimal number equal in value to the binary number.
Now convert a larger binary fraction (0.1101001101) into
its hexadecimal equivalent.
0.11010011012
REWRITE AS
77
MSB
LSB
0.1101
0011
three insignificant zeros in front ofthe MSB and one after
the LSB. Since these zeroes have no value, they should be
removed from the final result.
0100
YIELDS
0.D3416
BINARY CODES
Separate the binary number into 4 -bit groups, beginning
at the radix (binary) point (MSB). Note that the third group
contains only two bits. Since each group must contain four
bits, two zeros must be added after the LSB. The third
group will then have four bits with no change in the value
of the binary number. Now, each 4 -bit group can be converted into its hexadecimal equivalent. Whenever you add
zeros to a binary fraction, always place them to the right of
the least significant bit.
Now, a binary number containing both an integer and a
fraction (110110101.01110111) will be converted into its
hexadecimal equivalent.
110110101.011101112
REWRITE AS
MSB
LSB
0001
1011
0101.0111
YIELDS
0111
1B5.7716
The integer part of the number is separated into groups
of four, beginning at the radix point. Note that three zeros
were added to the third group to complete the group. The
fractional part of the number is separated into groups of
four, beginning at the radix point. (No zeros were needed
to complete the fractional groups.) The integer and fractional 4 -bit groups are then converted to hexadecimal. The
number 110110101.011101112 = 1B5.7716. Never shift the
radix point in order to form 4 -bit groups.
Converting hexadecimal to binary is just the opposite of
the previous process; simply convert each hexadecimal number into its 4 -bit binary equivalent. For example, convert
the hexadecimal number 8F.41 into its binary equivalent.
8F.411í
YIELDS
MSB
LSB
1000
1111.0100
0001
REWRITE AS
10001111.010000012
Convert each hexadecimal digit into a 4 -bit binary number. Then condense the 4 -bit groups to form the binary
value equal to the hexadecimal value. The number 8F.4116
10001111.01000001.,.
.
Now, the hexadecimal number 175.4E will be converted
=
into its binary equivalent.
175.4E16
YIELDS
MSB
0001
LSB
0101.0100
REWRITE AS
0111
1110
101110101.01001112
Again, each hexadecimal digit is converted into its 4 -bit
binary equivalent. However, in this example there are
Converting a decimal number into its binary equivalent is
called "coding." A decimal number is expressed as a binary
code or binary number. The binary number system, as discussed, is known as the pure binary code. This name distinguishes it from other types of binary codes. This section
will discuss some of the other types of binary .codes used
in computers.
Binary Coded Decimal
The decimal number system is easy to use because it is
so familiar. The binary number system is less convenient
to use because it is less familiar. It is difficult to quickly
glance at a binary number and recognize its decimal equivalent. For example, the binary number 1010011 represents
the decimal number 83. It is difficult to tell immediately
by looking at the number what its decimal value is. However, within a few minutes, using the procedures described earlier, you could readily calculate its decimal
value. The amount of time it takes to convert or recognize
a binary number quantity is a distinct disadvantage in
working with this code despite the numerous hardware
advantages. Engineers recognized this problem early and
developed a special form of binary code that was more
compatible with the decimal system. Because so many
digital devices, instruments and equipment use decimal
input and output, this special code has become very widely
used and accepted. This special compromise code is known
as binary coded decimal (BCD). The BCD code combines
some of the characteristics of both the binary and decimal
number systems.
8421 BCD Code. The BCD code is a system of representing the decimal digits 0 through 9 with a four -bit
binary code. This BCD code uses the standard 8421 position weighting system of the pure binary code. The standard 8421 BCD code and the decimal equivalents are shown
in Figure 4 along with a special Gray code that will be
described later. As with the pure binary code, you can
convert the BCD numbers into their decimal equivalents by
simply adding together the weights of the bit positions
whereby the binary l's occur. Note, however, that there are
only ten possible valid 4 -bit code arrangements. The 4 -bit
binary numbers representing the decimal numbers 10
through 15 are invalid in the BCD system.
To represent a decimal number in BCD notation, substitute the appropriate 4 -bit code for each decimal digit. For
example,, the decimal integer 834 in BCD would be 1000
0011 0100. Each decimal digit is represented by its equivalent 8421 4 -bit code. A space is left between each 4 -bit
group to avoid confusing the BCD format with the pure
binary code. This method of representation also applies to
decimal fractions. For example, the decimal fraction 0.764
would be 0.0111 0110 0100 in BCD. Again, each decimal
digit is represented by its equivalent 8421 4 -bit code, with
a space between each group.
An advantage of the BCD code is that the ten BCD
ELEMENTARY ELECTRONICS'July-August 1978
Understanding Microprocessors
=8+0+2+
= 11.251()
BINARY
GRAY
1
+0+0.25
DECIMAI
8421 BCD
0
0000
0000
0000
0001
0001
0011
0001
11.2510
0010
0010
0110
0011
0111
0101
0101
0111
1000
1001
1010
1011
1100
1101
1110
1111
To convert from BCD to binary, the previous operation
is reversed. For example, the BCD number 1001 0110.0110
0010 0101 is converted into its binary equivalent.
First, the BCD number is converted to decimal. 1001
0110.0110 0010 0101 = 96.625,. Then the decimal result
is converted to binary. 96.625,,) = 96, + 0.62510
Then the decimal result is converted to BCD.
1
0010
2
3
0011
4
0100
5
0101
6
0110
7
0111
1000
0100
1001
0001 0000
1101
1111
0001
0001
0001
0001
0001
0011
1110
1010
1011
0100
1001
0101
1000
8
9
10
ll
12
13
14
15
0001
0010
0100
0110
1100
Figure 4
code combinations are easy to remember. Once you begin
to work with binary numbers regularly, the BCD numbers
may come to you as quickly and automatically as decimal
numbers. For that reason, by simply glancing at the BCD
representation of a decimal number you can make the
conversion almost as quickly as if it were already in decimal form. As an example, convert a BCD number into
its decimal equivalent.
0110 0010 1000.1001 0101 0100
= 628.95410
The BCD code simplifies the man -machine interface but
it is less efficient than the pure binary code. It takes more
bits to represent a given decimal number in BCD than it
does with pure binary notation. For example, the decimal
number 83 in pure binary form is 1010011. In BCD code
the decimal number 83 is written as 1000 0011.. In the
pure binary code, it takes only seven bits to represent the
number 83. In BCD form, it takes eight bits. It is inefficient
because, for each bit in a data word, there is usually some
digital circuitry associated with it. The extra circuitry associated with the BCD code costs more, increases equipment
complexity, and consumes more power. Arithmetic operations with BCD numbers are also more time consuming and
complex than those with pure binary numbers. With four
bits of binary information, you can represent a total of
24 = 16 different states or the decimal number equivalents
0 through 15. In the BCD system, six of these states (1015), are wasted. When the BCD number system is used,
some efficiency is traded for the improved communications
between the digital equipment and the human operator.
Decimal -to -BCD conversion is simple and straightforward. However, binary-to -BCD conversion is not direct. An
intermediate conversion to decimal must be performed first.
For example, the binary number 1011.01 is converted into
its BCD equivalent.
First the binary number is converted to decimal.
1011.012=(1
(1 X 2°)
+ (0
X 23)+(0 X 22)+(1 X 21)
X 2 -1) + (1 X 2-2)
+
ELEMENTARY ELECTRONICS, July -August 1978
= 0001 0001.0010 0101
- 2 = 48 with
48=2=24
24=2=12
12=2= 6
96
6=2=
3=2=
remainder 0
LSB
0
0
0
3
0
1
1
-- MSB
2= 0
9610 = 11000002
0.625 X 2 = 1.25 = 0.25 with overflow
0.250 X 2=0.50=0.50
0.500 X 2 = 1.00 = 0
1
=
0.62510
1
MSB
I
0
1
4--
LSB
= 0.1012
96.62510= 96í0 + 0.625,,, = 11000002 + 0.1012=-1100000.1012
Therefore:
1001 0110.01 10 0010 0101
= 96.6251o=
1100000.1012
Because the intermediate decimal number contains both an
integer and fraction, each number portion is converted as
described under "Binary Number System. The binary sum
(integer plus fraction) 1100000.101 is equivalent to the BCD
number 1001 01 10.01 10 0010 0101.
Special Binary Codes
Besides the standard pure binary coded form, the BCD
numbering system is by far the most widely -used digital
code. You will find one or the other in most of the applications that you encounter. However, there are several
other codes that are used for special applications, such as
the "Gray Code."
The Gray Code is a widely -used, non -weighted code
system. Also known as the cyclic, unit distance or reflective
code, the Gray code can exist in either the pure binary or
BCD formats. The Gray code is shown in Figure 4. As with
the pure binary code, the first ten codes are used in BCD
operations. Notice that there is a change in only one bit
from one code number to the next in sequence. You can get
a better idea about the Gray code sequence by comparing
it to the standard 4 -bit 8421 BCD code and the pure binary
code also shown in Figure 4. For example, consider the
change from 7 (0111) to 8 (1000) in the pure binary code.
When this change takes place, all bits change. Bits that
were l's are changed to 0's and 0's are changed to l's.
Now notice the code change from 7 to 8 in the Gray code.
Here 7 (0100) changes to 8 (1100). Only the first bit
changes.
The Gray code is generally known as an error minimizing code because it greatly reduces confusion in the
electronic circuitry when changing from one state to the
79
next. When binary codes are implemented with electronic
circuitry, it takes a finite periods of time for bits to change
from 0 to 1 or 1 to O. These state changes can create
timing and speed problems. This is particularly true in the
standard 8421 codes where many bits change from one
combination to the next. When the Gray code is used, however, the timing and speed errors are greatly minimized
because only one bit changes at a time. This permits code
circuitry to operate at higher speeds with fewer errors.
The biggest disadvantage of the Gray code is that it is
difficult to use in arithmetic computations. Where numbers
must be added, subtracted or used in other computations,
the Gray code is not applicable. In order to perform arithmetic operations, the Gray code number must generally be
converted into pure binary form.
telephone. With six bits, a total of 26 = 64 different characters can be represented. These characters comprise decimal numbers 0 through 9, upper-case letters of the alphabet,
plus other special characters used for punctuation and data
control. A 7 -bit code called full ASCII, extended ASCII,
or USASCII can , be represented by 27 = 128 different
characters. In addition to the characters and numbers genetared by 6 -bit ASCII, 7 -bit ASCII contains lower-case
letters of the alphabet, and additional characters for punctuation and control. The 7 -bit ASCII code is shown in
Figure 5.
COLUMN I 0(3) 11(3)
4
010 001
SP 0
100
101
110
111
Q
P
/
a
b
p
q
B
Q
R
S
c
s
T
d
e
t
f
v
w
5
I
I7(3)
6
4321
2
0000
0001
0010
3
0011
4
0100
0101
0110
0111
1000
0
Several binary codes are called alphanumeric codes because they are used to represent characters as well as numbers. The two most common codes that will be discussed
are ASCII and BAUDOT.
ASCII Code. The American Standard Code for Information Interchange commonly referred to as ASCII, is a special form of binary code that is widely used in microprocessors and data communications equipment. A new name
for this code that is becoming more popular is the American National Standard Code for Information Interchange
(ANSCII). However, this course will use the most recognized term, ASCII. ASCII is a 6 -bit binary code that is
used in transferring data between microprocessors and their
peripheral devices, and in communicating data by radio and
2(3) I 3
ROW BITS
765
Alphanumeric Codes
1
1
5
6
7
8
9
10
1001
11
1011
12
13
14
15
1100
000
001
NUL
DLE
SOH
STX
ETX
EOT
ENO
ACK
BEL
DC1
DC2
DC3
DC4
NAK
SYN
ETB
CAN
EM
SUB
ESC
BS
HT
LF
VT
FF
1010
FS
1110
1111
_
"
#
$
%
&
'
(
)
*
+
_
GS
CR
SO
SI
1101
!
RS
US
IA
2
3C
4D
E
6F
7G
8H
9I
:7
;
K
<
L
- =
,
.
/
U
V
W
X
Y
Z
5
>
?
I.
g
h
r
u
x
i
v
j
z
k
1
M
N
O
I(t)
n
-(2)
o
-
DEL
Figure 5
NOTES :
(1) Depending on the machine using this code, the symbol
may be a circumflex, an up-arrow, or a horizontal
parenthetical mark.
(2) Depending on the machine using this code, the symbol
may be an underline, a back-arrow, or a heart.
(3) Explanation of special control functions in colums 0, 1.
2, and 7.
NUL Null
SOH Start of Heading
STX Start of Text
ETX End of Text
EOT End of Transmission
ENQ Enquiry
ACK Acknowledge
DLE
BEL
Bell (audible signal)
BS
Backspace
Horizontal Tabulation
(punched card skip)
Line Feed
Vertical Tabulation
Form Feed
Carriage Return
Shift Out
Shift In
Space (blank)
SYN
ETB
CAN
HT
LF
VT
FF
CR
SO
SI
SP
DC1
DC2
DC3
DC4
NAK
EM
SUB
ESC
FS
GS
RS
US
DEL
Data Link Escape
Device Control 1
Device Control 2
Device Control 3
Device Control 4
Negative
Acknowledge
Synchronous Idle
End of Transmission
Block
Cancel
End of Medium
Substitute
Escape
File Separator
Group Separator
Record Separator
Unit Separator
Delete
The 7 -bit ASCII code for each number, letter or control
function is made up of a 4 -bit group and a 3 -bit group.
Figure 6 shows the arrangement of these two groups and
the numbering sequence. The 4 -bit group is on the right
and bit 1 is the LSB. Note how these groups are arranged
in rows and columns in Figure 5.
To determine the ASCII code for a given number letter
or control operation, locate that item in the table. Then use
the 3- and 4 -bit codes associated with the row and column
in which the item is located. For example, the ASCII code
for the letter L is 1001100. It is located in column 4, row
12. The most significant 3 -bit group is 100, while the least
significant 4 -bit group is 1100. When 6 -bit ASCII is used,
the 3 -bit group is reduced to a 2-bit group as shown in
Figure 7.
In 7 -bit ASCII code, an eighth bit is often used as a
parity or check bit to determine if the data (character) has
been transmitted correctly. The value of this bit is determined by the type of parity desired. Even parity means
4 -BIT GROUP
7'
6
5
4
3
2
I
3 -BIT GROUP
80
ELEMENTARY ELECTRONICS 'July -August 1978
r
h
,e
Ce`
Understanding Microprocessors
Bit Numbers
5 4 3 2
Letters Case
Figures Case
Blank
E
Line Feed
A
Space
Blank
Line Feed
S
Bell
1
8
U
Car. Ret.
D
7
(1 )Depending on the machine using this code, the symbol
may be a circumflex, an up-arrow, or a horizontal
1
00000
0 0 0 1
0 0 1 0
0 0 1 1
0 1 0 0
0
0
0
0
001 01
0 0 1 1 0
0 0 1 1 1
0 1 0 0 0
0 0
0
0 1 0 1 0
0 1 0 1 1
0 1 1 0 0
0 1 1 0 1
0 1 1 1 0
1
1
0
1
1
1
1
0 0 0
0 0 0
0 0 1
0 0 1
0 1 0
0 1 0
0 1 1
1
0
1
1
1
1
1
1
1
1
1
1
R
J
N
3
-
Space
1
0
T
0
4
!
5
1
1
0
1
1
0
1
1
1
1
1
1
1
1
1
1
1
1
00
01
SP(3)
0
@
1
A
P
Q
0
0000
1
0001
2
0010
2
B
R
3
0011
#
3
S
4
0100
4
5
0101
S
%
C
D
E
6
7
0110
&
6
7
(
)
8
!
91
5
9
10
6
0
11
1011
+
12
13
14
15
1100
,
<
1110
.
>
1111
/
?
0
B
9
7
0
G
&
1
1
Figures
Figures
M
F
G
H
9
I
J
*
-
1101
T
U
V
W
X
Y
Z
=
K
L
M
N
O
/
I
L.(1)
_(2)
Figure 7
/
X
V
Letters
Il
2
1
0 0
0 1
1
0
1 1
10
65
Stop
1
1
3
8
Q
1
2
)
1
0 0 0
0 0 1
1
0
0111
1000
1001
1010
0
1
BITS
4321
(Apos)'
(Comma),
W
H
Y
P
1
0
ROW
$
Z
L
1
parenthetical mark.
(2)Depending on the machine using this code, the symbol
may be an underline, a back -arrow, or a heart.
(3)SP-Space (blank) for machine control.
COLUMN
Car. Ret.
F
C
K
NOTES:
eluding the parity bit, is an odd number. If the ASCII
code for G was transmitted with odd parity, the binary
representation would be 10001 1.
Type-Figures 5 6 Space
Letters
1
1
Figure 8
Then-Letters N OR T H Space
Then-Figures 0 Space
Finally-Letters S T R E ET
1
resent two separate characters. As shown in Figure 1-15,
one set of 5 -bit codes represents the 26 upper-case alphabet
letters. The same 5 -bit codes also represent various figures
and the decimal number series 0 through 9.
The remaining six 5 -bit codes are used for machine
control and do not have a secondary function. Two of these
5 -bit codes determine which of the 26 double (letter/figure)
11
characters can be transmitted 'received. Bit number
forces the printer to recognize all following 5 -bit codes as
letters. Bit number 11011 forces figure recognition of all
the following 5 -bit codes. For example, to type 56 NORTH
10 STREET, the following method is used.
BAUDOT Code. While the ASCII code is used almost
exclusively with microprocessor peripheral devices (CRT
display, keyboard terminal, paper punch/reader, etc.), there
are many older printer peripherals that use the 5 -bit
BAUDOT code. With five data bits, this code can represent only 25 = 32 different characters. To obtain a greater
character capability, 26 of the 5 -bit codes are used to rephits, including the parity bit, is an
the sum of all the
even number. For example, if G is the character transmitted, the ASCII code is 1000111. Since four l's are in
the code, the parity bit is 0. The 8 -bit code would be
written 010001 11.
bits, in Odd Parity. This means the sum of all the
1
1
1
POSITIVE POWERS OF 16
n
16n
0
1
1
16
1
2
3
4
5
6
7
8
256
409
655
104
167
268
429
6
36
857
772
435
496
6
16
456
729
6
NEGATIVE POWERS OF 16
n
I6 -n
0
1.0
1
2
3
4
0.062
0.003
0.000
0.000
5
906
244
015
25
140
258
625
7R9
062
5
1
ELEMENTARY ELECTRONICS/July-August 1978
81
POSITIVE POWERS OF 2
NEGATIVE POWERS OF
2"
n
0
1
0
1.0
1
2
1
0.5
2
4
2
3
8
3
4
16
4
5
32
64
5
6
7
n
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23^
24
25
26
27
28
29
30
31
32
128
256
512
1024
2048
4096
8192
16384
32768
65536
13107 2
26214 4
52428 8
10485 76
20971 52
41943 04
83886 08
16777 216
33554 432
67108 864
13421 7728
26843 5456
53687 0912
10737 41824
21474 83648
42949 67296
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
2
2-°
0.25
0.125
0.0625
0.03125
0.01562
0.00781
0.00390
0.00195
0.00097
0.00048
0.00024
0.00012
0.00006
0.00003
0.00001
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
0.00000
5
25
625
3125
65625
82812 5
41406 25
20703 125
10351 5625
05175 78125
52587 89062
76293 94531
38146 97265
19073 48632
09536 74316
04768 37158
02384 18579
01192 09289
00596 04644
00298 02322
00149 01161
00074 50580
00037 25290
00018 62645
00009 31322
00004 65661
00002 32830
5
25
625
8125
40625
20312
10156
55078
77539
38769
19384
59692
29846
14923
57461
28730
64365
5
25
125
0625
53125
76562 5
38281 25
19140 625
09570 3125
54785 15625
77392 57812 5
38696 28906 25
WHAT YOU HAVE LEARNED
The hexadecimal numbering system has a radix (base)
of 16. It uses the digits 0 through 9 and the letters A
through F.
2. Hexadecimal numbers 0 through 9 are equivalent to the
same values in decimal digits. The letters A through F
represent the decimal digits 10 through 15. Therefore:
decimal 9 = hexadecimal 9, but decimal 10 = hexadecimal A.
3. Conversion from decimal to hexadecimal is done the
same way as decimal to binary or octal. The decimal
number is divided by decimal 16, and the remainder
noted. The quotient is divided by 16 again, and again
the remained is noted. Division by decimal 16 continues until the quotient is 0. The remainders, from
least to most significant digit, are finally collected and
written as the hexadecimal number.
4. Conversion from decimal fractions to hexadecimal is
done in the same manner as decimal fractions to octal
or binary. In this case, the fraction is successively multiplied by 16, and the overflow noted.
5. Four bits of a binary number exactly equal 16. So, a
(Continued on page 92)
1.
82
FORGE FORWARD WITH
MICROPROCESSORS
The Heath Microprocessor Course may be purchased with the
Heath Digital Microprocessor Trainer kit, Heath Catalog number ET -3400. The Microprocessor Trainer is specifically designed to be used with the Course, and provides an ideal
platform upon which you may expand your knowledge of
microprocessor programming and interfacing techniques.
With the training you receive from the Course, and the
flexibility of the miniature Computer, you will be able to
begin on a level of technological experimentation you never
before dreamed possible! Circle number 31 on Readers
Service Coupon.
ELEMENTARY ELECTRONICS /July -August 1978
VOICE
'ELEMENTARY
ELECTRONICS
ACTIVATED CONTROL SWITCH. Self
contained, solid state. Has excellent ad.
estable sensitivity. Recorder activated
by voices or other sounds. Uses recorder
H OBBY
mike or remote mike. Single U bat. incl.
Great for home, business etc.
AMAZING ELECTRONIC
MICRO MINI MIKE:,
ïI
L,4
K
/
L
vo"
World's smallest, solid state, self contained with 1.3V
Mere. Rat. turn. Picks up most sounds and transmits'
without wires up to 300 ft. thrn FM Radio. Tuneable.
Use as mike, ampf., alarm & alert system, baby sitter,
hot line, etc. VOX only 524.95'. Mike only $18.95'
('plus $1.00 ea. pstg. & hand.) 13/11, MIC, cod. oh.'
Cal. res. add tax. Free data. Mail Order. Qty. disc.'
avail. AMC SALES, Dept.? 4,
9335 Lubec St., Box 928, Downey, CA 90241
MIART
I
J
_
DIGI-KEY
CORPORATION
-
(1,105!, I I,',rn,0i,
I
,m
-800-346-5144
TOLL
FREE
I'''''
I.C.'S
DON'T FORGET OUR
DISCOUNTS WHEN COMPARING PRICES
C.
TOOLS..
WIRE
SINKS
EATSM
law
SWITCHES
IX SOCKETS L PINS
DIODES
LOGSUPPLIES
IING
TESTING
FOR EF REE
ND DMORE
CAPACITORS
TRANSISTORS
ESH
DCLOCK
ATA ROOKSII
T`,ü 7:1il'ZxlCI4911'
218 681 6674
MINNESOTA RESIDENTS
RESISTORS
The "NIBBLER"
r
A MICROCOMPUTER AT A MICROPRICE!
!
NN.TTbled end
'4,4,11
40011
táe,
f41,
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ro;
sem.nrrxven.owMwH.cn
weW.rr.eoNafefs N
511,COM 1R
SI
mee
r
ye only RIO,"
NA.N
Memory
apendobl te NW
11ONod Nrlol l/O
IT
b-eN,..a.,e,
<,II1118143
To.F d,
Standard AV' by A.S. coed .«IE«Ta Pin edw<ennector MNern
for To.y rootnt.nn<
1111 IC'. ere
Sp.H&.
NN<NeorlWlly
NID N.1< In ROM end aK or RAM
!roll IEt.rfe<.d nitb CRT or Teletype
eK
CATALOG HUMAN/NIRI.NO
$149.90
enmal
e
for
Pole
e.lw Derails
SpIDERLESSRREADRDARDIN
CLOCK MODULES
IOR
Caller Wollo fer
55.00
MANI«,
SOFTWARE /HARDWARE MANUAL
WERACE
wITN POwER
FRDEE AP
111111111Mal
...e--
1E.,.
íI.EQ.:re
3.EE
,,,
POWE'
11
El
t
18406
023101
4114.96
µ
.Mf
JRU DIGITAL DISPLAY
RUlrtl( cAP.a,oRf
1
:''POW RA E102
I
1
I
RIPS -WRAPS
-
UNWRA
LED DIGITS AND
SE111]
-1 FOR OUR
- FLYER .
C
(ICKEi
IS«Rnuum POI
OLED
I
SOLEE
1
BEN CAn°,w5
v
CARBON FILM RESISTORS
PINS
MICROPROCESSORS
8080A
CHIP
SET
EVEN MORN
DOUBLE DIGIT DISCOUNTS SAVE YOU
HANDLING
CHARGES
.
COOL.,
Lop, To.
BISOOP
O
EDAM os
VOLUME
DISCOUNT
=<
NS
i
Nn
II46fnN.Iwo
ifNNHWNEN
...
/If
..'
L
U.... ln. ifti
0,001
STRANDSPerRE
POOR
®5[3()0
BILL
BOX 2355.
woo. or
DIGI-KEY
CORPORATION
GODBOUT ELECTRONICS
OAKLAND AIRPORT, CA 94614
o(110
FREZ
CIRCLE 12 ON READER SERVICE COUPON
ELEMENTARY ELECTRONICS/July-August 1978
CATAIIW
Filrfnl0,l ml.Tm Puaneñ MN
TWOImEli11
CIRCLE 43 ON READER SERVICE COUPON
83
ELECTRONIC
SYSTEMS
Box 9641 San Jose,
P.O.
CA 95157
(408) 374.5984
FOR CATALOG INCLUDING( PARTS LISTS AND SCHEMATICS,
SEND A SELF ADDRESSED ENVELOPE WITH 24e POSTAGE.
RS - 232 / TTL
INTERFACE *
1.4110n
«NM!
UART
&3 BAUD
RATE
GENERATOR*
Part no. 101
Converts serial to parallel and
parallel to serial
Low cost on board baud rate
generator
Baud rates: 110, 150,
300, 600, 1200, and 2400
Low power drain +5 volts and
-12 volts required
TTL compatible
All characters contain a start
bit, 5 to 8 data bits, 1 or 2 stop
bits, and either odd or even
parity.
All connections go to a 44 pin
gold plated edge connector
Board only $12.00; with parts
$35.00
8K
STATIC
RAM
2102 Static memory chips
Memory protect
Gold contacts
Wait states
On board regulator
S-100 bus compatible
Vector input option
TRI state buffered
Board only $22.50; with parts
Uses
$160.00
To Order:
wsa
OD
1
Part no. 232
Converts TTL to RS -232, and
converts RS -232 to TTL
Two separate circuits
Requires -12 and +12 volts
All connections go to a 10 pin
gold plated edge connector
Board only $4.50; with parts
$7.00
Converts RS-232 to 20m 4
current loop, and 20mA current
loop to RS -232
Two separate circuits
Requires +12 and -12 volts
Board only $4.50. with
parts $7.00
TELEVISION
TYPEWRITER
l
TAPE
INTERFACE *
Converts a low cost tape
recorder to a digital recorder
Works up to 1200 baud
Digital in and out are TTL-serial
Output of board connects to
mic. in of recorder
Earphone of recorder connects
to input on board
Requires +5 volts, low power
drain
DC
POWER
SUPPLY *
Part no. 6085
Board supplies a regulated
+5 volts at 3 amps., +12, -12,
and -5 volts at 1 amp.
Power required is 8 volts
AC at 3 amps., and 24 volts AC
C.T. at 1.5 amps.
Board only 812.50; with
parts $42.50 excluding
transformers
Part no. 112
Tape Interface Direct Memory
Access
Record and play programs without bootstrap loader (no prom)
has FSK encoder/decoder for
direct connections to low cost
recorder at 1200 baud rate, and
direct connections for inputs and
outputs to a digital recorder at
any baud rate.
S-100 bus compatible
Board only $35.00;
with parts $110.00
Board $7.60; with parts $27.50
No coils
Part
no. t07
RF
MODULATOR *
Converts video to AM modulated RF, Channels 2 or 3
Power required is 12 volts AC
C.T., or +5 volts DC
Board $7.60;
with parts $13.50
Apple II
Serial I/O
Interface *
Part No. 2
Baud rates up to 30,000
Plugs into Apple Peripheral
connector
Low -current drain
RS-232 Input and Output
SOFTWARE
Input and Output routine from
monitor or BASIC to teletype or
other serial printer.
Program for using an Apple II
for a video or an intelligent terminal. Board only
$15.00;
with parts $42.00; assembled
-
and tested
4
l'art no. 600
ea* MMwYJfr.13111.littKW*
NA
'P
CI,
ea
rtitc.:+
Play and record Kansas City
Standard tapes
TIDMA*l:.°
Part no. 300
8K Altair bus memory
Part no. l
RS-232/TTY
INTERFACE
-
- $62.00.
`11111'
;Jo
c'a
P. .i3,
t11111
,.,_
ad
tl::ii Ca
. g9
e-
I-2:
4-6.4
-t_.,
Part no. 106
Stand alone TVT
32 char/line, 16 lines, modifications for 64 char/line included
Parallel ASCII (TTL) input
Video output
IK on board memory
Output for computer controlled curser
Auto scroll
Non-destructive curser
Curser inputs: up, down, left.
right, home, EOL, COS
Scroll up, down
Requires +5 volts at 1.5 amps,
and -12 volts at 30 mA
All 7400, TTL chips
Char. gen. 2513
Upper case only
Board only $39.00: with parts
8145.00
MODEM *
Part no. 109
Type 103
Full or half duplex
Works up to 300 baud
Originate or Answer
No coils, only low cost components
TTL input and output -serial
Connect 8 ohm speaker and
crystal mic. directly to board
Uses XR FSK demodulator
Requires +5 volts
Board $7.60; with parts $27.50di
Mention part number and description. For parts kits add "A" to part number. Shipping paid for orders
accompanied by check, money order, or Master Charge, BankAmericard, or VISA number, expiration
date and signature. Shipping charges added to C.O.D. orders. California residents add 6.5% for tax.
Parts kits include sockets for all ICs, components, and circuit board. Documentation is included with
all -products. Dealer inquiries invited. 24 Hour Order Line: (408) 374-5984.' Designed by John Bell.eur
CIRCLE 35 ON READER SERVICE COUPON
84
ELEMENTARY ELECTRONICS/July-August 1978
THIS SPECIAL ONE CENT SALE IS FOR MAGAZINE ADS ONLY
POLY PAKS' PENNY
ONE
CENT
EVOLUTION
LIBE
THESE ONE -CENTERS ARE THE CENT -CIBLE WAY TO SHOP AND SAVE!
E
S
SKI'
7Ní
11771.90.
Typa
C 997400
f 9N7401
L 597403
2 for
Each
2 for
Type
Each
9.19
.19
$.20
.20
5N7465
.19
.25
.25
.29
.55
.29
.79
.59
.59
.29
.39
.99
1.49
.39
D 597406
5117408
597410
997413
SN7414
C 597418
597420
597423
.19
.39
.65
.29
.19
.29
.25
.25
.29
.25
.25
.29
.19
.69
.69
.65
.99
1.35
1.25
1.35
SN7426
5N7427
D 597430
597432
597437
597438
5117440
5N7442
597443
597444
997445
597448
597447
SN]448
597450
597451
597453
SN7454
597455
997460
597462
597464
D SN7470
D 597471
.20
.26
.20
.20
.22
.20
.40
.68
.30
.20
.30
.26
.26
.30
.26
.26
.30
.20
.70
.70
.88
1.00
1.36
1.26
1.36
.20
.20
.20
.20
.20
.20
.20
.20
.19
.25
.19
.19
.21
C 597404
C 597405
Cl
THIS NEW LIST OF "ONE -CENTERS"
HELPS FIGHT INFLATION!
T11 S & OP AMPS!
cet.
No
BUY ONE AT SALE PRICE,
GET 2ND FOR ONLY 14 MORE.
.19
.19
.19
.19
.19
.19
.19
.19
597472
597473
597474
5N7475
587476
D 597478
U 597480
Cl 587482
597463
997485
D 597488
5117488
5N]490
597491
D 5147492
C 597493
597494
C
C SN7495
C 597496
C SN7498
9974100
9974107
5974112
5874113
5974114
5974121
9874123
5974128
5874126
5974132
C 5974140
5974141
,
D 5974145
.20
.28
.26
.26
.56
.30
.80
.80
.60
.30
.40
1.00
1.50
.40
1.96
.70
.80
.46
.50
.70
.70
.70
.70
1.50
.40
.26
.20
.26
.60
.70
.60
.40
1.28
1.00
1.50
1.95
.69
.79
.45
.49
.69
.69
.69
.69
1.49
.39
25
.19
.25
.49
.69
.59
.39
1.25
.99
1.49
5N74285
Cl
D
D
.80
1.50
.50
.70
1.50
1.76
.86
.88
1.26
.50
.76
1.76
5.51
1.76
4.51
4.26
5.50
1.78
4.50
4.25
5N74251
1
D
D
O
code, T-70.220 Power Tah.
Type
C LM300H
5.50
.46
.80
1.30
.80
1.30
1.30
1.30
1.30
1.20
1.76
1.10
1.29 1.30
1.29 1.30
.59 .60
LM320K-15
LM320T-8,5
C
C
1.913229
LM324N
LM339N
LM340K-5.6.8,
12.15, 18.
O LM340T-5, 6, 8,
12, 15, 18. 24
1.913509
1.79
.29
2.25
1.69
L.
1.49
111153111
LM53211-11 .29
.75
D LM555V
.79
LM558V
1.00
1195619
.99
LM565N
.49
LM703H
.29
LM704H
LM709941 .25
.39
1917109
.79
LM733N
.89
LM739N
[
D
Cat
I
POWER TABS!
D
D
D
D
D
IO2áo
O
I
35
8!
5
J5.119
120
1.80
139
O 600
.30
2.26
1.70
1.50
.30
.76
.80
1.01
1.00
.50
.30
.26
.40
.80
.90
11418005
1M4195
18,4250
D 1.5175451
D LM75453
D LM75491
D LM75492
1M79494
D
100
200
400
600
800
0 1000
11.
I
22S
230
is
2
2
194001
1N4002
194003
184004
154005
194008
200
400
600
800
114007
1000
IO for $.65
10 for .75
10 for .85
SO
100
10 for .99
10 for 1.29
10 for 1.39
10 for 1.49
MICRO MINI
1.5 AMP
1
1C
20
20
20
20
for
for
for
20
for
for
20 for
20 for
6.50
631
731
631
for
for
for
2for
1030
1430
and volta
10 for 5.59
S0V
D 100V
200V
A9
10 for
10 for
.79
10 for 19
10 for 1.08
10 for 1.19
400V
600V
0 800V
g
1.30
1.40
130
20
20
20
20
20
with mounting hardware.
for .70
for .80
for .90
for 1.10
for 1.20
Cat. No
793936
7045055
794037
7115087
O
OF
V
Style
10
50
1S
P.C.
P.C.
P.C.
P.C.
15
50
O 20
O
20
15
25
25
15
15
Axial
P.C.
Cat 793584
and value
No.
Sale
10 for $1.00
for 1.00
8 for 1.00
6 for 1.00
10 for 1.00
10 for 1.00
t
le SAI,E
20 for 51.01
16 for 1.01
16 for 1.01
12
1.01
20 for 1.01
20 for 1.01
YOUR CHOICE S for $1.00
1C SALE
10 for $1.01
by Cat. No.
*792135 JUMBO RED LEDS
O 11792137 MICRO RED LEDS
0712790 JUMBO RED CLEAR LEDS
07112792 JUMBO
AMBER
D 07112140 MICRO GREEN LEDS
C
COPYRIGHT 1978
-
Is
M
O
Sale 2 for
$1.29 $1.30
1.39
140
1.95
1.86
'AS
End
V.
50
3
J
loo
H
t
600
600
1000
200
400
146
c
OFF
9 .36
45
11
AT OUR
PRICE
SALE
2 for 9 37
.46
2for
.79
.90
1.19
139
11
2 fo.
2 for
2 for
62
.80
2
2 for
1
SALE
14
.91
1.20
140
GET 2
FOR 1t
MORE
Salo
ATTV S
order by Cat.
No. 795210 & voltage & *adage!
6,2V
1S SALE
Sale
1 Watt
8.2V
7.5V 5 fer $1. 10 for $1.01
9.1V
12. V
8.2V Sfor 1. 10 for 1.01
9.1V Sfor 1. 10 for 1.01
15. V
1.01
S for 1. 10 for
D 18. V
11.1/
1.01
12.V
S for I. 10 for
24. V
D 15.V
Sfor 1. 10 for 1.01
30. V
POLY PAKS INC.
BUY
1C
SALE
for s1. 6 for 5101
3 for 1. 6 for 1.01
3 for 1. 611 1.01
3
6for
6for
6 for
6for
3tor I. 6for
Sfor
3 for
3 for
3 for
3
for
3 for
1.
1.
1.
1.
1. 6
1. 6
for
for
1.01
1.01
1.01
1.01
1.01
1.01
1.01
8 -PIN MINI -DIP (0792123)
D 14 -PIN DIP 07111308
18 -PIN DIP 07111309
18 -PIN DIP #7X3378
24 -PIN MS1/ IP (t#711
O 29-PIILPIN MSI/DIP (30 7)
O 5 -PIN TO -5 (#711111307)
*********
'6 Ohms
*
3. N"
L9.
. tuare, srrrwdriyer shaft.
bl. 14 , tt. ('vane. "PC'
1.49
1.95
1.49
501
100K
N. N3864
WRITE FOR
POLY PAKS
CATALOG
LW!
FEATURING
BEST BARGAINS
IN ELECTRONICS
130
2 for
$5.96
4.96
1.51
for
$1.51
2.96
1.96
1.96
2
2.95
1.95
1.95
BRIDGE
RECTIFIERS!
for $1.20
for 120
for 1.20
for 120
for 120
for 1.20
1.20
is
for $1a
e
.2:::b: i. ca.. ryé...al am,
1.50
1.96
400
Order by Cat No. 712447 & voltage
sale
2for
P
0 50
$129 $1.30 2
ci100
1
200
1.69
1.70
1.992
2.00
400
D 800
230
2.51
Order by ('at. Nu.
value
D No. 793863 25 turn uplIht, typ. 84 e
2K
e****N****
4
a.
2 for
$1.99
$1.98
FULL WAVE
10 AMP
..784
1.30
******.t***********
leads
800 o 2OK'
111
for 1.19
for 1.19
4 for 1.19
2
2
54.96
4.51
6.96
Each
$ 1.49
:
8
8
6
12
4
8
8
150
ISO
SPECTROL "SKINNY -TRIMS":
*} 100'
10K/
200 SR
y
)
2 for
Each
210,
5
dM
129
4 for$1.19
3 for 1.19
3 for 1.19
6 for 1.19
Each
$5.95
4.95
IC SOCKETS!
i
CARTWHEEL
RECTIFIERS
ZENERS!
LEWIS!
O.Nr
4PDT'
6 AMP
KLINIC
LYTIC
793269
Cat.
Order
by
Type
SPDT
SPOT'
DPDT
Each
2 for
$4.51
1.50
Each
DIP SWITI'HES= f 779
2 SWITCHES ON A DIP (#793668)
3 SWITCHES ON A DIP ((#7N3669)ì
6 SWITCHES ON A DIP #793671
1.01
1.01
1.20
for 1.96
2 for 1.51
2
6.95
12V TRANSFORMER, 300me, pc leads, lloprL (0793412)
12V TRANSFORMER IA, 110/220prL open Name (#794040)
D 24VCT TRANSFORMER, 300m., open frame, IlOprl. (#793323)
D 29V /111 -CAD CHARGER PAK.plagin, 12Snuo.125 VAC í#1(07N40881
.66
.76
.88
1.00
1.20
1.20
4 for
450
1itA1SSFORMEHS:
1.01
4 for
$4.95
AMPLIFIERS!
1.96
1.96
2.96
4.96
$4.50
(#793902)
8 WATTS ON A BOARD, with huM-In preamp (0795040)
O 9 WAITS ON A CHIP, T..hie TA7205 (#1N5057)
3 WATTS ON A CHIP, G -E PA 263 (0711522)
No.
with chrome handles, complet.
20for 5.60
1-
1.01
3.51
2 for
4 for
4 for
12 for
1.49
1.49
RELAYS!
SWITCHES?
BULLET RECTIFIERS! TOGGLE
3 Amps, 125 VAC contacts.
Ord.. byCat No. IN
1.50
SPOT 12V BLOCK RELAY SA contacts (0794032)
SPDT 12V REED RELAY, iA contacts 0714094)
SPDT 12V SENSITIVE. 2000 ohm cell) 07N3044A1
SPST 24V REED RELAY, noms open,* style,1250 dnw (#765175)
2.96
6for 9120
Each
(0713178)
CONDENSOR MIKES, sensitive, 500 ohms,
COMMUNICATIONS MIKE, SOO ohms, CB-HAM 0714074)
D NOISE CANCELLING MINE, Nom -CB, S00 ohms
1.01
1.01
1.01
1.01
ONE CENT SALE
1
's'ES!
N/I'/t II/HO
I1V
Cl
10 for
10 for
60-N for
10 for
2 for
10 for
2 for
2 for
2 for
2 for
2 for
3
TWIN CONE SPEAKER, hl-fl, for car'n'home (0795059)
24. x 5" OVAL SPEAKER, 8 ohms (07112553)
2 x 6" OVAL SPEAKER, 8 ohms (6793454)
13.01
14.51
1.01
2.51
for $2.01
for 2.01
for 2.01
for 2.01
for 2.01
for 2.01
8011. for 2.01
100for 2.01
6 for 2.01
30 for 2.01
200 for 2.10
60 for 2.01
20 for 2.01
60 for 2.01
400 for 2.01
400 for 2.01
200 for 2.01
80 for 2.01
30 for 2.01
200 for 2.01
200 for 2.01
100 for 2.01
40 for 2.01
SO for 2.01
30 for 2.01
300 for 2.01
200 fer 2.01
400 for 2.01
400 for 2.01
120 for 2.01
60 for 201
op...
SPEAKERS:
1.50
20
30
20
300
200
60
-
-
1.96
1.01
1.20
1.01
for
for
2 for
4 for
2 for
(7N)
for $1.19
for 1.00
2 for 1.19
2 for 1.19
6 for 1.00
2 for 1.00
2 for 1.19
1 for
1.9$
150
9.96
2
2
-8
.
101
4.96
IO for
1.00
RELAY, norm. open 12-24 VDC, 1250 ohms, dip style (07/1 5175)
1.49
1-VEEDER ROOT COUNTER, 000.999, resettable, panel mt (07115081)
1.00
2 -DUAL GATE MOSFET, slur. to 3N200, 3N167, for RF & Mixer (#795101)
2.50
1
-TRACK TAPE HEAD, with plus' n' cord (07043468)
10 _CALCULATOR KEYBOARDS, 20 keys and more 793524)
$2.00
2.00
1s _SLIDE VOLUME CONTROLS, asstd values (7113057)
2.00
CRYSTALS, may Include CB, Ham & more (793250)
10
2.00
150__ MOLES IC SOCKETS, no a .Nip, cut to length (713144)
2.00
100 _ TERMINAL STRIPS, from 2lugs up (7113136)
2.00
30 NE-2NEON LAMPS. NI 100% good (7112613)
2.00
40 -ft. SHIELDED CABLE. 1 00nd, mikes, honor, (0793377)
2.00
5O_ TRANSISTOR. ELECTROS,..std values, styles (792747)
w/amp
(7113625)
2.00
3 -SOUND TRIGGERSsound Niggers scr
15 69 TEST INDICATORS, leads, grelno-wheat (713526)
2.00
2.00
100
CAPACITOR SPECIAL dbcs, mylar, ydcs, more (712738)
MINI TRIMPOTS, to 1 me g, 1 turn, NW (7113345)
2.00
30
10__ VOLTAGE REGULATORS, hobby LM320, 340, TO -3 (793330)
2.00
2.00
30 _PANEL SWITCHES, tildes, rotaries, mod, etc (7113268)
RESISTOR SPECIAL,
to 1W, carbon, metal 793054)
2.00
200
HALF WAITERS, reolotors, carton, metal
2.00
200
100
NATIONAL IC BONANZA, sneers, 7400s ROMS (7042860)
2.00
2.00
40 HOBBY LEDS, ..std types, mostly useable(7/2859)
2.00
15
LM340T VOLTAGE REGULATAORS, Sto 249, TO -220 (782635)
TWO WAITERS, resistors, carbon-motel marked (7112735)
2.00
100
2.00
100
POLYSTYRENE CAPS, ..std values, voltage, hi -Q (792729)
2.00
SO __ THERMISTORS, resistors that change with temp (794089)
2.00
20
BRIDGES, untested, 2, 4, 6, 10, amp, full wave (7N4022(
LAMP'N'SOCKET SETS, mkro, 1.5V, T2 (713957)
2.00
2S
2.00
15
MIXED READOUTS, hobby, untested, .127, .3, .5, etc. (7N3619)..
2.00
150 -. QUARTER WAITERS, resistors, metal Rkn, marked (7N3413(
2.00
100. PLASTIC TRANSISTORS, untested, RO -92 (7112604)
2.00
200
PREFORMEDRESISTORS. 1, 1, 1W, marked, asstd (7/2608)
200
200 PRECISION RESISTORS, %, X, 1W, 1%, 2% marked (792428)
2.00
60 DIPPED MYLARS, shiny Relsh, asst values (71 2597)
2.00
30 VOLUME CONTROLS. audle, linear, asstd values (712421)
1.00
S
7.5 VOLT ZENER DIODES, 1 watt `785187
1.00
9.1 VOLT ZENER DIODES, 1 watt (71151681
5
ICs,
30 -ft. WIRE WRAP WIRE, 30 gage. for
trminais (07N 3803)
1.00
1.00
$
TANTALUM ELECTRO CAPACITORS, 22uc, 25V (#71151811
I ALARM CLOCK CHIP, MM5316, 4-d Hs (7111759)
2.95
S
PANCAKE PHOTOCELLS, 600 to 151( ohms (71 2939)
1.00
for marker` n (793898)
1. 100KHZ MARKER CRYSTALS
1.95
1__ MOTHERBOARD EDGE CONNECTOR, 106 pins, .125" (793987)
3.50
48-PIN EDGE CONNECTOR, .156" spacing )7N3963)
I
1.95
1
JOYSTICK, two 10K pots, for computers, TV games (715037)
2.95
4.95
1
CHARACTER GENERATOR, 5 x 7 Mostek MK 2002P (713898)
venez.
Amp!
5
1.95
1.00
(0793705)1.19
1-SPST
s"
1031
2 for
2 fer
13.00
TRANSPORT, with preamp (07130101
7 -SEGMENT READOUTS
Cat No.7N-148147 (SCRs)
Ca, Ne. 711440968A (Triers)
V.
Each
1C
SALE
50 5 .95
2 for 5 .96
100
1.25
2 for
1.26
200
1.95
2lor 1.86
400
230
2 for
2.51
600
295
2 for
2.96
2.26
2.51
for
for
2
2
2
730
1.49
DIGIT LCD WRISTWATCH DISPLAY. (07113960)
-GE-FLUORESCENT ^MIMES", Mua. 0.9^ dur, 9.1n tuM 07113684)
SPERRY FLAT MIXTES, orange, 3^ dual 41/R51)9715014)
2
D SPERRY FLAT NIXIES, orange, .3", 14 -dig (071115)
D MAN -3 BUBBLE READOUT..19" rad, corn Cath. (0713338)
(07111503)
n
2
MAN4 READOUTS bubble end, com. eodo..19"
END -10 BLOCK READOUT, .122 " com cathode (#792082)
8 -DIGIT READOUT, led, rom csthod, red (0795190)
FND.503, .5" red, com cathode, 7-seg. (0792949)
25 AMP POWER
STUD SCRS, TRIACS
i
I
6,50
D
for
for
for
for
9.95
31/4
Cat. Mo. 711870685 - 250 amp
IC SALE
V.
Loch
50 5 4.95 2 for 5 4.96
for $ 2.96
for
3.96
for
4.96
ter
7.51
for
9.01
fer 10.51
2ís 1231
2
2
2
2
2
2
for 91.50
2
2
2
2
4 fo.
100
1-PLESSEY TV SIDEBAND FILTER, for than. 3 or 4 (#793975)
S-TRANSITORS, 2N3904 equal, NPN, switching (07/15209)
1 -METER, 50uA, 11" square, 0.20db
1
Sale
Miniature!
782382
712313
D
,
voltage
by Cat Ne, 7N2273
V
11
SALE
Each
SO
$1.95 2 fue $1.96
1.50
1.49 2 M
O 100
1.70
200
139 2 for
2.00
1.59 2
O 400
1
No.
792378
792379
782380
782381
D
1.75 1.76
1.95 1.96
1.19 1.20
.39 .40
.39 .40
.79 .80
.79 .80
.59 .60
D LM3909V
Order by Cat. No. and Type
Rectifiers
1N4000 Epoxy
Price
MORE!
Type
P1V
1
D
.50
.49
111835009
1
.30
.79 .80
.99 1.00
1.99 2.00
.79 .80
.69 .70
.99 1.00
.65 .66
[] LM302811
150 amp
-
11
600
600
Cat. No.
79 2377
.29
rl LM1414V
0 LM1458V
25 AMP BRIDGE
Order RECTIFIERS
,
$ 700
1.19
400
Typ(
LM741V-11
1
N 1)II'.
Each 2 fa-
[] LM1304
I¡ LM1310
r]
LM 1312
011er by Cat No.
57111560-QUADRACS
21or
S*le
RV
50
713567
50 9 2.95
3.95
100
4.95
200
7.50
Cl
400
9.00
D 600
1030
600
1000 1230
I#7N3448.TRIACS 7111730-sCR
'
No.
V.
Order by Cat. No. and
IO -5:
.1.11
HI-POWER STUD RECTIFIERS
MONEY BACK
GUARANTEE
\SURS! TRIAI :S:
:SS
QI "ADtA1voltage!
14
1.80
LM374H
LM376V
LM377N
LM381N
G
YOU GET 120-DAY
r----iso AMP
Each 2
10
K
L LM3709-N 1.29 1.30
5.49
.45
.79
1.29
.79
1.29
1.29
1.29
1.29
1.19
1.75
1.09
C LM301H-V
L LM308V-H
C LM309K
[ LM311H-V
LM318V
LM320H-5. 12. 15
Mini dìp.
Tyne
2 for
Each
V
2
4.95
_
POP -AMPS AT "CENT -CIBLE" PRICES
Case
9149
pp
-8 -TRACK TAPE
ISSUE
Sale
CABINET. 31/4 a 10 a v" daeo, spkn larme. 97115201)
08
-LCD THERMAL INDICATORS,88.1F,7s1".R.aile(#7N5195)
-JOYSTICK, four 100K is with knob 0711380881
1-EECO THUMBWHEEL SWITCH, BCD. 0-7 (07042870*)
1
1.26
1.26
1.50
1.00
1.75
.85
.85
1.25
.49
.75
1.75
D 5974284
2
1.76
1.00
1.00
1.00
1.76
.80
.70
1.00
1.00
1.28
1.26
1.20
1.00
1.26
.69
1.49
Description (Order by Cat. No. In parentheals1
1- WOODGRAIN
1.26
1.25
1.75
.99
.99
.99
1.75
.79
.69
.99
.99
1.25
1.25
1.19
.99
1.25
1.25
1.25
1.49
.99
.79
1.49
.49
9974148
5974150
5974151
D 5974153
9974154
9974155
5974156
5974157
D 5974158
5974160
5974161
5974163
5974164
$974165
[ 9974166
5974173
ci 5974174
D 5974175
5974177
5974179
5974180
5974182
D 5974190
9974191
5074192
5874193
SN74194
n 5974199
5974197
5974199
5974200
Qum.
2 for
Each
Type
63:
RIBBON
CABLE:
Order n),
Cal. N1. 7N3939 i.
and Cooductiirs
Gand.
20
0 26
Cl 34
40
7
-ft
4-11.
3-N.
3 -ft.
Sale
11.98
1.98
1.88
1.98
IC Sale
í4N.31.99
8-11.
8-11.
6 -ft
1.99
1.99
1.99
3r
Terms: Add postage Rated: net 30
Phone: Wakefield, Mass. (61 7) 245-3829
Retail: 16-18 Del Carmine St., Wakefield,
MINIMUM ORDER
$6.00
-
POLY PAKS
942
C.O.D.'s MAY
BE PHONED
P.O. BOX
-N7
LYNNFIELD, MA.
/Il' 01940
CIRCLE 18 ON READER SERVICE COUPON
ELEMENTARY ELECTRONICS/July-August 1978
85
1
WIREWRAP
PRECUT WIRE
WIRE WRAP SOCKETS
8
14
- No more cutting & stripping by hand
Re11abN - Good, clean, uniform Strip
Economical - Cheaper than using bulk wire
tie K0
W
1
192
106
at 5066 =
=
50 It. roll at Sl 99
100 It. roll at 2.95
2r/K
1/3t/K
35
.31
.36
.32
=
.35
54
47
.63
.44
.69
.41
120
1.10
95
90
B4
1.25
84
1.15
78
1.08
.68
.95
.64
.89
62
1.65
1.55
1.42
1.25
1.15
1.09
43
63
B4
58
78
pin'
1.30
24 Pin
91
28 pm
40 pin
46/x
=
39
71
46
18pin'
UM.
End 8 Side Staekable
2:
in.
78
2.40
3
in.
.82
86
90
260
39 in.
4
in.
1898
.94
321
1.02
in.
1.06
342
385
385
6
5.52/K
5.93/K
6.34/K
5.21/K
5.52/8
6.75/0
716/K
5.86/6
1.29
405
425
445
4e5
7.57/0
798/K
8.39/K
880/K
69 m.
1.32
4.&5
9.6/K
9
9 . tn.
1.36
a0
585
525
9221/K
10.03/K
to in.
1.45
5.51
1044/0
10
41
6
.
7
7'
8
in.
In
1.15
In
120
125
in.
Add,
1
In
82
Awe
.30
.54
59
xC .áz
All
rices
WIRE WRAP TOOLS
The game we have been selling for $21.50 in kit form. NOW complete, ready to go including VIDEOC UBE, the TV interface,used
for iterfacing minicomputers and cameras, as described in August
RADIO -ELECTRONICS. Games have 2 levels of skill, LED readouts for scoring, 2 joysticks which move players in all planes, not
just vertical & horizontal. Game sold for $79.50 in Boston stores.
STOCK NO.5495R Complete TV game & VIDEOCUBE $18.95
$7A
JY 9 5
6.19/K
HOBBY WRAP
Model BW 630
6.52/8
6.85/K
718/0
115 V primary. Sec.1-12.6V@1.0 A. ct. Sec.2-33.5V tapped
13.1 V @1.OA. Sec.3- 140V @100 ma. 2Lbs. 4"x2"x23/4".
)
Batteries & Charger
WSU 30 Hand Wrap -Unwrap Strip Tool
WSU 30M, for Modified Wrap
/0
8.50/K
8.83/K
STOCK NO.6772R
5.95
6.95
95
2
13 lbs. 41/2"x43/4"x 33/4"
STOCK NO,6554R
INTERCONNECT CABLES
Ribbon cable connectors for connecting boards to
front panels, or board In board.
l
$6.95
J
I I
a
1004
100
100
a
250
500
500
'
5"
6"
150
3"
3'
500
f'
250
100
4"
1
4
"
5'
250
100
SINGLE ENDED
6"
6'i'
'
14
24 pin
18
pin
pin
24 p.
124
pin
134
205
224
245
1.33
1.44
2.24
2.33
2.55
24"
48"
1.52
1.65
205
2.63
3.40
252
276
4,
91
2.91
3.17
5
1
Choose one color
or As onment
1
14
16
I
DELTA ELECTRONICS
ue
ATLANTA, GA. DELTA ELECTRONIC HOBBIES
dIP
Kits
CIRCLE 42 ON READER SERVICE COUPON
COMPONENTS
SPECIAL
C.B. POWER SUPPLY KIT
METERS
.4.
I"
Unused
1,
electronic
N8W20128
#7W7034211
#8W20127
#7W70343
or $5.00/3
2 PC
inputs, controls, case and speakers for
complete working stereo system.
Sh. Wt. 5 Lbs. .7E70464
$12.88 ea
a
.
.
We supo
y3 ode,
line
t
rd, switch, trans-
Great for CCTV
or Micro -Computer
Monitor'
tot
4?
P
envy
.
These reconditione
TV interface section. Has
some 30 IC's, including 2
555 timers and lots of
CMOS stuff. Also has two 7 -segment .5"
LED displays
all on 2 PC boards.
Also: 2 - joystick controls (each with 2
10K pots); 2" 8 ohm speaker; large
sloping -top case & more & more!
Sh. Wt. 5 Lbs.... 8GE0028 ....$7.88
solid state monitors
-
.
-
1. 5V
per cell. Used, good cond.
Sizes are: AA -oversize; &
sub -C. (Check dimensions)
TRANSFORMERS
duty ferro -resonant trans rmers
for your power supply, all are center tap.
Wt.
Volts Amps Order No. Price
12" Diagonal
TV
RECHARGEABLE,
HI -CURRENT
With New CRT!
games that are missing the
i
'-
40 16 -CT
20 16 -CT
30 15 -CT
35
25
25
&30 -CT
3
5
30 80 -CT
have a new CRT in- \,
I
stalled & are checkThey can $98.88
ed out.
display up to 80 characters X 16 lines, ac-
cepting std. comp. video signal. 75 ohm
input via SO -239 connector, 115VAC. 12
40 Lbs.
page manual incl. Qty. Ltd.
Order No. 8A30200
$98.88
RG80077
$19 50
8G80073 S15.50
8G80074 $16.50
8G20197
$9.88
FREE JUMBO CATALOG:
-
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3,000 surplus items
electronics, optics
& more! Circle reader service card now!
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.If you mention this ad: SAY "E-78"!
c9lt0-129.>2KO,
86
CIRCLE
$69.95/pair
KIT No. 2
NiCad's
former and instructions. Good for 20
mp r. Wt. Order No.
You supply case & cosmetics. Size (In.)
amps.
Super heavy duty!
Sh. Wt. 16 Lbs. .635x1.9110.60 3 oz 7V70468
1.20 5 oz 7V70470
$19.50 ea or $55.00/3 .865x1.6
#7C7005
8811 each or $8.00/10
Video
-
.
VOLT AUTO
BATTERY CHARGER
12
Q
is
-
Reconditioned
VIDEO GAME
an
I5811s
.
Super cabinets, size
21x12x8". Includes 8"
woofers w/whizzers; 4"
dome tweeters; crossA SUPERB ENSEMBLE OF Components
overs; damping; hardincluding: Flaredome 3" tweeter; two (2)
5" Middlers; heavy-duty 12" Woofer: & ware and instructions.
System sells for $198 if
an L -C -R crossover wtih two controls.
bought ready to go,
For optimum performance, this system
B&F kit price only
should be mounted in an air tight enclo$69.95/pair!
45 Lbs.
sure of at least 2 cubic feet in volume (aOrder No. 7ZU 70283
vailable separately, send for catalog). Al
nico V type magnets, 5 70 Watts, 25 to
SPEAKER SYSTEMS
20,000 Hz., 6 - 8 ohms. Simply GREAT!
30 Lbs. ...8EU80063... $119.50/pair
(pair=8 speakers, for two 4-way systems)
boards, already wired, which make up a
stereo amplifier. Plus a power transformer, line cord and instruc tions. You add
...
Four types available, all
measure 2-3/8" square. Use
these with our P.S. kits.
0- 8 Amp Gauge
0-10 Amp Gauge
0-15 Amp Gauge
0-20 Amp Gauge
Sh. Wt. 12 oz.
.$2.00 ea
Speaker Kits
SPEAKER SYSTEMS
KIT No. 1
-
STEREO POWER AMP KIT
A complete kit of parts, including
1
"'FAT'
4 -Way Co
Speaker
16 Watts RMS Total
A complete kit which puts out 10 to 24
VDC at 2 amps, regulated, 115 VAC in.
Can be wired for contant 13.8VDC, ideal
& compact for C.B. Kit includes PC card,
components and instructions ... just add
your own case. Super as a bench supply!
Sh. Wt. 6 Lbs. ...6C60498....$14.88
2.
5A, 10 to 24VDC Reg. P.S. KIT
A simple, adjustable regulated power supply. Kit includes all components, vector
board and complete schematics. All you
add is the case. A powerful supply!
Sh. Wt. 15 Lbs ...6M160301 ...$14.88
3. 5V, 1A LOGIC POWER SUPPLY KIT
Includes all parts needed to build a regulated 5 volt, amp power supply. Case
not supplied. A real B&F bargain! 3 Lbs
7C70267 ....$6.00 ea
3 for $16.88
,,
gd617-3884705
5151 Buford Hwy. Doaraville, (Atlanta) Ga. 30340
Dealer Inquiries Invited
Power Supply Stereo Power
AMP
Aa
RETAIL OUTLET
CIRCLE 16 ON READER SERVICE COUPON
1.
Mk LEI
P.O. Box 2, 7 Oakland St.
Amesbury, Mass. 01913
Orders under $25 and COD's. add $2
others, shipped pd in U.S. via UPS
For Blue Label (Ai)All Porr 1st Class. add $1
We accept Visa & Mastercharge
Most orders shipped same day
135 E. Chestnut Street 4A
Monrovia, California 91016
Phone (213) 357-5005
2/30.00
337
302
Information:
PAGE DIGITAL
ELECTRONICS
t`
pin
DOUBLE ENDED
6"
12"
5
W
7250 IL Roll Bulk
$16.95 ea.
TRIAD -N67A ISOLATION transformer. 115 or 230 VAC to 115
AC. 150 VA. Limited quantity. 7 lbs. 4"x4"x31/2".
STOCK NO.6788
$7.95 ea.
2/15.00
$19.95
2
2
@
$2.95 ea.
2/5.00
Two 115 volt primaries,(can be used on 230V). 4 secondaries. 11.5V
@ 4.8 A, 23V @ 9.0 A., 14 V. @ 20 A. and 125 V 1.5 A.
$11.00
BT 30 Extra Bit
66/K
K
1
($6.95 Value)
./K
8.1717
NEW TRANSFORMERS
+
With Free Wire Kit
7.53/K
WIRE KITS
e
g, u
ludo gold
3.69/0
422/6
4.55/0
4.88/K
4.71/6
5.12/0
2.80
3.00
5'. in.
5
1000
4.301K
27
Tin sockets and 2 -level sockets available
30 Kynar snipped r' on each end. Lengths are overall
Colors Red,Blue,Green,Yellow.BICk,Orange.While
Me packaged in plastic bags. Add 254/length for tubes,
500
27
Gold 3 -level Closes Entry Sockets
4
100
HOCKEY SOCCER GAME PLUS
VIDEOCUBE-TV INTERFACE
10-56
100-249 250-999
.29
29
32
20 pin
22
Bulk Wks
354/I1.
25-99
38
.39
41
pin
16 pin
Fast
100 pcs of 3" at
100 pcº 016" al
10-24
42
1-9
Why buy wire on rolls?
PRECUT & STRIPPED WIRE IS:
Precut Wire
TV
5 ON
READER SERVICE COUPON
Fantastic cabinets designed for direct
dispersion of high freq. and wide dispersion of low freq. Size: 17x10%9x9'/"
Sold with 8" woofers, 4" dome tweeters,
cross-overs and instructions.
35 Lbs.
Order No. 7ZU70242
$49.50/pair
POSTAGE Please add postage, :1I1 material is
F.O.B. Peabody, Ma. No C.O.D.', please.
Massachusetts Residents add 5% sales tax,
Use
PHONE ORDERS WELCOME!
your Bank Americard, Master Charge
or American Express Credit Card!
$10.00 min. on all charge orders.
B&F ENTERPRISES
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119 FOSTER STREET
PEABODY, MA. 01960
Tel. Orders: 1617) 531-5774
ef'Jt
sti`Avem
.
o)
ELEMENTARY ELECTRONICS/July-August 1978
...now that
Radio Shack has the
amazing new Realistic 2001 with built-in microprocessor!
The PRO -2001 makes possibe continuous,
automatic recept on of six UHF and VHF bands
for ail kinds of action -police, fire, Ham,
weather, mobile telephore, railroad
communications and more. And with
its microprocessor you can program
it for any 16 of 36,650 frecuences,
without buying crystals!
Enter familiar area frequencies. Use
the digital keyboard to punch -in actual
frequencies for monitoring, storing or
exploring-no cades or switches to slow
you down. A special ENTER button reduces
accidental entries. Digital readout stows
which frequencies are being scar ned, monitored
or programmed into the rremocy. Arc yot can
monitor any frequency without entering it in -o the
Mobile use in nome states and I-,caliaes
master c'_
r: yMiBPyMK
may be unla
-
it's like having a seventeenth channel
scanner
for even greater versatlitv!
Search for "unknown" frequencies. The
2001's powerful search capability lets
you find new, often unpublicized
channe's. Just enter lower and upper
limits (they can even be in different
bands) and select the search speed.
The rest is automatic!
"Traditional" deluxe scanner features.
LED channel incicators and individual
lockout buttons. Automatic or manual
scan. Switchaale scan delay. High-speed skipper circuit. Built-in speaker, jacks for recorder,
headphone, external speaker. With power cables
'or home or mobile use. The Realistic® 2001
revolution in action radio. About $400.*
-a
tul or require
a
permit
--
check with local authorites.
SOLD ONLY WHERE YOU SEE THIS SIGN:
G4R
These credit cards honored
at most Radio Shad; stores.
and products may
vary in Canada.
* Prices
ftadio l'haek®
A
ELEMENTARY ELECTRONICS/July-August 1978
DIVISION OF TANDY COR?ORATION FJRT WORTH!, TEXAS 76102
OVER 7000 LOCATIONS IN NINE COUNTRIES
87
Sabtronics Multimeter
JOHN MESHNA JR. Inc.
PHOTO FLASH complete on PC board w/
flash tube in reflector, 2 ni -cads & camera
connecting cable. Cycles in 3 seconds $7.00
8 SWITCHES in MINI DIP
1.80
10 SWITCHES in MINI DIP
2.00
1.25
AA NI -CADS fast charge
5 WAY BINDING POST US made
.35
U -FIX -EM TV gamés, w/power pack
& video Cube in original boxes (sold
11.00
for $50)
JUMBO LED .187 diam. long leads 6/1.00
.75
TV CHEATER CORDS 6 ft
LIQUID CRYSTAL thermometer,
to 108 degrees F
MULTI USE xfmr puts out 140
4/1.00
volts, 12.6, 6, 33.5 volts Many
home projects
SEISMIC DETECTOR radio trans-
1.50
reads 86
mitter, used in Viet Nam for troop
detection.
4.00
COPY LENS FROM ZEROX in mount.
10.50
874 focal length iris f4.5 to f8
U -FIX -EM hand calculator 4 function
3.00
LAMBDA solid state regulated slim line
volts
supply
12
DC
8
amps
50.00
power
ULTRASONIC transducer 37 or 40
Khz
2.00
The above includes data on alarm system
PL 259 coax connector
.75
SO -239 coax socket
.60
TOUCH TONE ENCODER KIT, pad, chip
& instructions
12.95
IR NIGHT VIEWER, new ready to use,
see in the dark
199.00
All above FOB LYNN MASS (you pay
shipping) Amazing 64 page catalog free
JOHN MESHNA JR. Inc.
PO Box 62, E.Lynn, Mass
01904
CIRCLE 24 ON READER SERVICE COUPON
ALDELCO ELECTRONICS COMPANY
NEW IMPROVED DIGITAL ALARM CLOCK KIT
0.5 LED Display
12 hour format
-naillamike
Snooze Feature
Elapsed Timer
f
rx
17
'r
Simulated Wood Grain or Black Leather Cabinet
$24.95
12 or 24 Hoar Clock Kit. Similar to Above but without Alarm or
Timmer features.
Only $23.95
Crystal Time Bees Kit for 12 Volt DC me
4.95
STUD RECTIFIERS
10 Amp 50V .45
10 Amp 200V .65
40 Amp 50V 1.20
40 Amp 200V 1.60
FULL WAVE BRIDGE
2
2
3
3Amp 200v
VOLTAGE REGULATORS
T0220 Package
Positive
Negative
$1.00
$1.25
7805
7806
25
25
25
25
7905
7906
7808
7812
7815
LM309H
LM309K
LM723
FETS
Amp
50V
Amp 200V
Amp
50V
7912
7915
7918
$1.10
1.10
.55
200V
400V
600v
1000V
DIGIPEAKE-A
Includes schematic
Volt, 6 Amp.
+15 and -15 2 Amp
5
5
for $1.00
FND 70 CC 0.3 Display LED .49
FND 500 CC 0.5 Display LED
.89
CLOCK FILTERS 24
Red, Blue, Green or
Amber
x
5%"
.80 ea
$17.95
$16.95
haw ransistors.
Send stamp for catalog.
We
MA 1003 National Car Clock Module
With 3 push button switches and f Item $19.95
New aluminum cabinet for MA 1003
6.95
Gran, Yellow or Orange LEDS
MC1458P
SPECIAL
Only 49e
AMATEUR 1V CONVERTER
Coven 420 to 450 AM TV
BAND. Works on unused
Commercial TV Channel.
KIT
ONLY
$39.95
ASSEMBLED
$49.95
B$1NKY-FLASHER-TIMER
KIT
Includes ' 555, PC Board
Parts & Instructiom $2.50
SPEAKERS 8 OHM
2%" $ .75
2%" 100 Ohm
2%"
1.25
$1.50
214x5" 3.00
VARIABLE POWER SUPPLY KITS .5 Amps 5.15 Volt DC $6.95
.5 Amps 12.28 Volt DC 6.95
add $1.00 per kit shipping
Visit Our Store. Hours 9:00 AM to 6:00 PM Mon. to Fri. Sat 9:00
AM to 2:00 PM. Phone Orders accepted. Visa & Master Charge.
ADD 5% FOR SHIPPING. ORDERS UNDER $10.00 add $1.00.
Foreign Orders add 15% shipping (except Canada & Mexico). Send
Certified Check or Money Order in LISA funds.
ALDELCO
2281E BABYLON TURNPIKE, MERRICK, N.Y. 11566
1516) 3784555
88
Computer Readout
(Continued from page 70)
$9.95
Kit of parts for power supply
.55
JUMBO RED LEDS 6 for $1.00
Monsanto MV5053 Jumbo Red
LED and holder
25c each
1.50
4.00
5.50
8.50
or install jumpers when calibrating the
meter. Matter of fact, the calibration
is unusually fast and accurate.
Two cailbration procedures are suggested in the manual: The first is the
user's own calibration; the second is an
alignment using equipment normally
found in a calibration laboratory. Since
the typical builder will not have access
to lab calibration standards Sabtronics
will do the job for $15 plus $3.50
shipping and handling. Since user calibration based on the supplied standards resulted in an overall accuracy
better than 3% we really can't see
spending the extra money for a lab
calibration.
Accessories Later. Unlike many kits
which have complicated modifications
when circuit changes or accessories are
added after construction is completed,
the Model 2000 DMM provides for
its accessories with no hassle. Each
accessory, such as a Nicad pack, or
charger, is a separate accessory which
installs independent of the main circuit
board. Two of the rear cover panels are
factory embossed to indicate the drill
area for mounting jacks, while accessory printed circuit boards install directly over posts already moulded into
the cabinet. No modifications are required on the main board for accessories. The accessories connect only to
the two power wires that normally connect to the C -cell power pack.
Final Performance. We initially calibrated the meter against the built in
LOGIC PROBE KIT
1.55
40673
MPF102
Amp
Amp
Amp
Amp
.35
.50
.50
.85
(Continued from page 38)
CIRCLE 30 ON READER SERVICE COUPON
possible white moves for its single temporary black move, and having saved in
memory the board layout that gives
white the highest value (best position),
the processor now goes back to black to
find another piece it can move (or the
same piece but to a different square). It
then flips over to play white and repeats
the previous process. It will find the
white move that gives white the best
situation and it will save that board layout. Now the computer has two board
layouts saved; one that gives white the
best situation in response to the first
black move, and one that gives white
the best situation in response to the
second black move (which assumes the
first test move never happened) .
Here comes the key to the whole
decision process. The computer must
choose between its two pretend black
moves based on the two saved board
layouts. Which move would you choose?
standards. Slightly better accuracy was
attained by using a high grade multi meter as a reference and adjusting the
2000 DMM so it provided the same
readings on voltage, current and resistance as the reference meter. For general use either calibration procedure
is satisfactory.
Overall, the 2000 DMM works very
well, though it takes somewhat longer
than is common for readings to settle
down. A reading from the powerline
took seven seconds to settle; our regular lab digital meters take between two
and four seconds. Considering the 2000
DMM costs a fraction of the price of
our lab meters, a few extra seconds of
waiting is worth the savings ,in cost.
(A resistance reading took from one
to three seconds depending on the
range.)
The X10 multiplier seemed somewhat unusual because our other instruments don't have this feature. However, once we got some experience it
made no difference; if anything, it provides an advantage in allowing user
movement of the decimal point, a particularly attractive feature in light of
the 100% overranging. (You can expand some low value readings to two
or three decimal places to provide maximum accuracy.)
Overall, the Sabtronics 2000 DMM
is an excçllent value for the money.
Its basic cost of $69.95 includes no
accessories other than the holder for
four C -cells. Even the test leads are
an optional accessory, though any set
of standard leads will fit the banana
jacks.
For additional information circle No.
52 on the reader's service coupon.
Easy. The one that gives white the
worst board layout situation of the two.
Now the computer finds the next black
piece it can move, finds the white move
that is best for white in response to that
black move, compares the board pattern to the one previously saved, and
chooses the one (and therefore its black
move) that is worst for white (best for
the computer) of the two. This process continues until all black pieces
have been moved in memory that can
be moved. When the processor is finished it knows which of its black moves
will be of least benefit to white. It
makes that move.
Now all of that logic may sound very
defensive, but it really is both offensive
and defensive because what can be
least good for white may be, for example, that black attacks white's queen
or puts the white king in check. This
approach of taking the least of the set
of best moves is known as a "min/max"
(for minimum of the maximum) solution. It is a powerful decision -making
tool that humans can use if they can
keep enough information in the head at
ELEMENTARY ELECTRONICS/July-August 1978
one time-something the computer is
designed to do.
We discussed computerized backgammon in our last article. So far there
are no backgammon computers that I
am aware of that have different levels
of play. It is conceivable that a higher
level would mean the computer is doing
a look -ahead into the odds of your
rolling various dice combinations and
consequently moving pieces in certain
ways. Fidelity is said to be lookng at the
backgammon market but, besides that,
they have an advanced Checkers Challenger available right now that has four
Disappearing Antenna
(Continued from page 74)
small neon lamp encased in a red plastic
enclosure (which also telescopes into
the fender). Keying the transmitter
causes the lamp to light, creating a red
glow at the tip. This glowing lamp is
called a "Breaker Beam," and while it
serves no purpose when transmiting or
receiving, it does announce to other
CBers in the area that you are on the
air.
The antenna requires a one-inch hole
(which can be made with a chassis
punch or hole saw) in the fender,
cowl, or trunk, and at least 17 -inches
clearance below the mounting surface.
If you don't have at least 17 -inches you
must find another location, so check
before you punch the mounting hole.
The mounting is essentially the standard "eight -ball," or "universal" mount
used by many popular radio antennas;
you shove the antenna through the hole
from the bottom, hold it vertical, position a plastic ball and metal weather cap, and run down the mounting nut.
Unlike most telescopic or disappearing antennas which permit water that
enters the system to collect and run out
the bottom of the motor end into the,
trunk, the EV-Garne antenna provides
a plastic drain hose that carries off the
water accumulation to the. outside.
As normally supplied the Model -500
system is completely automatic without
modification by the user. In addition to
the CB/AM/FM coupler a special
Electronic Relay Box is also supplied.
It is this device that really makes the
Model -500 the most convenient of dis-
appearing CB antennas.
The Electronic Relay Box has seven
wires. Three connect to a special harness plug that provides power to the
antenna's motor. One wire is the
ground. One goes to the battery, another to the ignition switch accessory
terminal (or the dashboard's accessory
circuit), and the final wire-which has
a twin socket-connects to the power
wire of both the CB transceiver and
the radio. Inside the Electronic Relay
levels of play and a basic unit that has
one level. The advanced unit uses standard checkers openings and looks four
moves ahead on level four. Because the
game is a thousand times simpler than
chess, the computer can do a very
thorough job of strategy. It is said to be
very hard to beat. For more information on any of the Fidelity units, please
write them directly. You should find the
chess and checkers units in your local
department store.
Next issue will cover more up-to-date
micromania. Stay tuned and keep the
ideas flowing.
Box is a sensing circuit that senses
when either the radio or CB, or both, is
turned on. When it senses power flow
to the radio or CB it automatically
supplies power to the antenna's motor,
causing the antenna to rise to its full
length.
If both the radio and CB are turned
off the relay box senses zero power and
applies reverse current to the antenna
motor, causing the antenna to automatically retract. If you should inadvertently park and leave the car without turning off the radio(s), as soon as
the relay box senses there is no power
through the ignition switch accessory
circuit it applies power to the antenna's
motor, causing the antenna to retract.
Unless you leave your ignition key in
the switch in the on or accessory position the antenna is always retracted
when the car is parked. (Yes, the motor
automatically turns off when the antenna is fully telescoped.)
The antenna is adjusted for minimum SWR on the Citizen's Band by
adjusting the Breaker Beam holder at
the tip-a wrench is provided so you
can loosen the holder's set screw. After
extended use the CB/AM coupler
might require re -adjustment.
No Extras. There are no extras for
the EV-Game Model 500 antenna;
everything is supplied. First, there's the
antenna itself which has a short, attached coax cable and power harness
(for the motor) terminating in a connector. Then there's the CB/AM/FM
coupler which gets mounted near the
antenna. A power wire extension harness, with connectors and two extension coax cables, brings the power and
signals from the dash to the trunk. The
coax cables connect to the CB and
radio, the power cable connects to the
Electronic Relay Box, which in turn
connects to the radios as previously
described. Rounding out the l:it is a
plastic drain hose, antenna mounting
strap (for the motor end) and mounting screws. Everything you need for
the installation is supplied.
The EV-Game Model 500 Fully
Automatic Antenna is priced at $79.95.
For additional information circle No.
75 on the reader's service coupon.
ELEMENTARY ELECTRONICS/July-August 1978
Q. Which
magazine has
the widest
scope of
equipment
test reports?
--ií stereo
BUYERS'
Ahí
GUICZE
Read it regularly for the
most in consumer audio
information and advice.
Allow 6 to
8
weeks for celivery of first copy.
Hi-Fi/Stereo BUYERS' GUIDE
gives you the absolute tops in
number of equipment test
reports per issue. We don't just
test the top of the line, we
report on all levels of more
manufacturers' lines than anyone else.
you're a
"best -buy"
buyer, don't
miss a single
If
issue!
Mail this coupon to
NI -Fl / Stereo
BUYERS' GUIDE
Box 1855 GPO
New York, NY 10001
Enclosed is $2.98 for 6 issues of HFSBG
(outside U.S.A., possessions send $4.00)
Name
Address
City
State
lip
off regular subscription rate
SAVE$2.97
$5.12 off newsstand rate.
118F0 10
89
You and Your Computer
(Continued from page 45)
popular personal computers uses four
nulls and a control signal at the end
of each line of a BASIC program;
this encoding precludes its acceptance by other personal computers.
Similarly, it cannot accept recordings
from a time-share system. It's a common problem. Some day there might
come about a common recording or
encoding standard.
Q-What is an "acoustic coupler"?
A-An acoustic coupler is a modem that
is connected to the telephone circuit
by placing a telephone's handset in
the modem's sound -absorbing cradle
-which contains a speaker and microphone to couple sounds from the
modem to the phone and vice-versa.
This contrasts with a "hard wired"
modem that is wired directly to the
telephone line(s).
Q-What would cause intermittent recordings from my computer? I'm using a Kansas City interface and a
Panasonic cassette recorder. Sometimes I load a program and find
there's errors, even on the safety
dump.
A-If you can get good recordings occasionally it's a sure sign both the
interface and recorder are okay.
Most likely you are using a really
cheap tape, and dropouts-which normally go unnoticed with sound recordings-are dropping bits out of
your dumps. Even at 300 baud you
need decent tape such as TDK-AD,
Maxwell UD, and AVDEX, all of
which are excellent to at least 4800
baud. When recording baud rates
above 4800 a special data cassette is
recommended.
Q-What is the difference between audio
and data cassettes, and why are data
cassettes at least twice the cost of
audio cassettes?
A-The primary difference between an
audio and data cassette is the pressure pad. The one on the data cassette is oversize, generally made of a
special low-friction material, and
often costs more than the tape itself.
In addition, the tape (supposedly)
has a more uniform coating, is less
prone to oxide flaking, and most important, is certified for a specific
minimal baud rate. It is claimed the
shell and internal construction is better but we haven't noticed construction having any effect when it comes
to personal computers.
One advantage of the personal
computing data cassettes such as
those from AVDEX is they have
short tape loads; you don't pay for
90
30 minutes worth of tape when you
need about thirty seconds worth.
(Data cassettes often come in several
"short" lengths.)
Q-What
is
meant by "serial" and
"parallel"?
A-In serial, each
bit of the seven bits
(or eight with parity) making up an
ASCII character, or binary information, is transmitted to or from a computer in sequence, one bit after the
other. Special timing and encoding
tells the computer which bits make
up a character. In parallel form all
bits are simultaneously transimtted,
so no timing or special encoding is
required. TTY uses a serial format.
An inexpensive tape reader such as
the Oliver uses the parallel format,
thereby allowing you to feed the tape
as fast as you can pull it through the
reader. All you must be certain of is
that the computer's I/O matches the
terminal or peripheral: serial for
serial and parallel for parallel. You
cannot mix the two, such as feeding
a serial TTY through a parallel I/O
port. (Note. Though a TTY feeds
and receives in serial unless specially
modified, a TTY punched tape is recorded parallel-the TTY makes the
"conversion".)
Q-How much memory can be installed
in a personal computer?
A-The maximum amount of memory
determined by the particular CPU
and the size of the power supply.
Some kits provide for something like
16K, 20K, or 24K in the main cabinet, with an extra cabinet and power
supply needed for additional memory. Other kits have a heavy-duty
power supply, usually a cooling fan,
and can accommodate up to 48K of
memory. New memory ICs draw
relatively little current and you can
now get 8K of memory in less space
than you needed for 4K, and the 8K
takes less current. As a general rule,
is
6K to 8K of available memory-in
addition to the memory needed for
your higher language such as BASIC
-is more than enough for 99% of
the average personal computer's programs. You need a lot more memory
-upwards of 20K-when you start
getting into filing systems, or FORTRAN. But if you're into files and/
or FORTRAN you really need a disc
system.
program that follows the specified
header. Basically, it's a simplified
filing system for cassette storage.
Some BASICs make provisions for
headers, or more commonly, "files";
others don't, and the BASIC loads
everything coming off the tape.
Well, that about wraps up those questions most frequently asked by our
readers. We would like to answer your
letters individually but it has become
physically impossible to do so. But we
will keep track of your letters and
comments and from time to time cover
those questions most frequently asked.
Meanwhile, each issue of e/e will keep
you up to date on the latest in personal
computing hardware, some software,
and most especially, those oddball gadgets with particular appeal and value
to the hobbyist and experimenter. So
keep those letters and cards coming.
Future of AM Stereo
(Continued from page 73)
receivers are envisioned as having response equal to that of stereo FM tuners, on the order of 15 kHz. The introduction of AM stereo will finally force
AM broadcasters to pay attention to the
range of audio frequencies they transmit. Likewise, equipment manufacturers
will devote more attention to the AM
section of AM/FM receivers. Current
design practice seems to regard the AM
section almost as a necessary evil.
DXers will find themselves hunting
for distant stations broadcasting in
stereo, and the improved AM receivers
will be a boon for BCB DXers. Other
special equipment, such as directional
BCB loop antennas, will likely become
available. Yet the improved audio range
of AM stereo stations will cause more
co -channel interference and may make
,.digging out weak foreign stations on
the "split" frequencies between the even
10 kHz frequencies a difficult task.
And even those who only tune the
shortwave bands may not be left outinternational shortwave broadcasts are
AM, after all! Wouldn't you like to
spend a cold winter evening listening
to South Seas music from Radio Ta
hiti-in stereo?
Q-What
is a "Header"?
header can be several things, but
it generally refers to a code, often a
single letter, placed in front of a
A-A
program when several programs are
recorded on the same tape. The computer can be programmed to search
for the header and load only the
"I'll say one thing, Lady! You
were on the right track!"
ELEMENTARY ELECTRONICS/July-August 1978
Hey, Look Me Over
(Continued from page 12)
Audio-Technica markets these new headphones at audio dealers throughout the
U.S.A. Get the complete specs direct from
Audio-Technica U.S., Inc., 33 Shiawassee
Avenue, Fairlawn, OH 44313.
designated RP -1172 by Heath, is offered
with complete 3, 5 and 8 -channel R/C
systems at special discounted prices. It
is also available separately. The Skyhawk systems are ideal for beginning
R/C pilots because they include everything needed for operation except fuel
...
.,....'
Auto Power Amp
The Panasonic Auto Products line of hifi car audio products now includes a
t0
0
CIRCLE 31 ON READER SERVICE COUPON
and starting battery. The Skyhawk features hot molded wing, tail and fuselage
sections and has a 48 -inch wingspan.
Fuel capacity is from 4 to 6 ounces, and
the aircraft is complete with a .25 -cubic
in. engine. Full R/C systems featuring
the Skyhawk and Radio Control gear
start as low as $239.90 mail order. For
further information, write for a free catalog to Heath Company, Dept. 350-550,
throughout the country. For further information, write to Vaco Products Company, 1510 Skokie Blvd., Northbrook,
IL 60062.
Mobile Hi-Fi Amplifier
Royal Sound's new line of mobile highfidelity components include the Model
IA -400 Mobile high-fidelity integrated
amplifier. The IA -400 is a precision preamplifier equalizer control console with
separate bass and treble controls, automatic power control, LED power indicator, easy input/output connection terminals and high quality heat sinks to
easily handle the high power capacity of
this 20 watt RMS per channel unit. This
model carries a suggested consumer
price of $120.00. Royal Sound Corn -
Benton Harbor, MI 49022.
CIRCLE 73 ON READER
Magnetic Screwdriver
SERVICE COUPON
Vaco's magnetic screwdriver No. 70035
has a powerful magnet built into the
shank which holds interchangeable bits
and also holds the screw. The unique
Vaco comfordome handle allows fatigue free driving. A removeable smooth dome
nylon cap stores the three extra bits
four-way 51 -watt power amplifier. Model
CJ255Z is a power amp with dynamiccally boosted four-way sound. It features
four.inputs with four output connections
to work with a four -speaker system. The
CJ255Z offers a full 10 -watts per channel without distortion, 50 -watt power
maximum. The unit is designed to be
mounted either under the seat, trunk, or
anywhere else where it would be out of
the way. Priced to sell at $79.95. Panasonic Auto Products are available from
any Panasonic dealer nationally. For
more information, write to Panasonic
Auto Products, One Panasonic Way, Secaucus, NJ 07094.
For Beginning R/C'ers
Heath Company's latest addition to its
line is the Delta Products Cessna Sky hawk R/C model airplane. The Skyhawk,
Hi-Fi Reports
(Continued from page 15)
way it acts on a record can be more
easily understood if you try the following simple experiment: Take a broom
and drag it along behind you while
walking at a constant speed; now push
the end of the handle straight down.
Note how the floor end of the broom
moves slower across the floor. Now pull
the handle hack up-the broom moves
faster. On a stereo turntable, when the
cartridge is pushed down the stylus
slosss down and when it bounces back
up it mopes faster across the surface of
the album. This causes wow and flutter,
au oscillation in the frequency which is
quite noticeable in some circumstances.
:.:
CIRCLE 74 ON READER SERVICE COUPON
a full line of mobile
high-fidelity equipment. Get all the facts
by writing to them at 248 Buffalo Ave.,
pany, Inc. markets
Freeport, NY 11520.
;>14,4,
rai-
Simply Basic
(Continued from page 58)
CIRCLE 84 ON READER SERVICE COUPON
inside the handle while the fourth bit is
in use. The bits include 3/16 -in. and
9/32 -in. slotted and #1 and #2 phillips.
Sells for $6.04. Vaco tools are found on
dealers counters and peg -board racks
To eliminate this it is desirable to
keep the stylus angle constant which is
just what Shure's Dynamic Stabilizer is
designed to achieve. The small brush is
also made to conduct static electricity
oft the album and to clear the grooves
of dust.
In a/e's test lab the Shure V15 IV
easily lived up to expectations. Excellent results were attained throughout
the recommended vertical tracking force
(VTF) range of 0.75 to 1.25 grams.
(Note: since the Dynamic Stabilizer
brush exerts a negative tracking force
of 0.5 grams it is necessary to set the
VTF to 1.75 to get a net VTF of 1.25.)
The frequency response measured within +1.5 dB and -1.0 dB from 20 o
20,000 Hz. The channel balance was
within I dB from 20 to 20,000 Hz and
the stereo separation was 23 dB at 1000
ELEMENTARY ELECTRONICS/July-August 1978
10 in line 420 to the desired number of
guesses.
Your computer system may require
you to use quotations around each
letter in the DATA statement (Line
300).
Okay. Now load MIND BENDER, and
test your brain power.
Hz and 20 dB at 15,000 Hz. To get
more information about Shure's V15 IV
cartridge circle No. 65 on the reader's
service coupon.
Hi-fi Report will be a regular feature
in ELEMENTARY ELECTRONICS from
now on and I want it to be responsive
to your needs. Unfortunately we don't
have space to report on every item that
you inquire about, hut, if there is sufficient interest in a specific piece of
equipment, I will get the lab to check
it out.
Remember, if you are in the market
for your first audio system or want to
upgrade your present system, shop
around-prices vary from dealer to dealer and you can usually save a bit off
the retail price, but you can never
save by shortchanging yourself on quality.
91
Understanding Microprocessors
1
(Continued from page 82)
POSITIVE POWERS OF
n
0
1
1
8
2
64
512
409
327
262
209
167
3
4
5
6
7
8
8
8"
6
68
144
715
772
2
16
4 -bit binary number can be represented with a 1 -digit
hexadecimal number. Therefore, to convert from binary
to hexadecimal: Begin with the least significant bit and
separate the binary number into 4 -bit groups and then
convert each 4 -bit group directly to its hexadecimal
equivalent. This will give you the hexadecimal number
equal in value to the binary.
6. Convert binary fractions to hexadecimal the same way,
but instead of beginning with the least significant bit,
the most significant bit should be the starting point.
7. When you convert a decimal number to a binary
DX Central
(Continued from page 25)
gram logs, of what you heard. This
would include at least a description of
the programs (news, popular music, political commentary, etc.) . Better yet, the
actual name of the program (BBC
Radio Newsreel, DX Merry-go-round,
etc.) and pick out specific items or
announcements (News Items about Middle East negotiations, a description of
Polish country dances, etc.). And indicate, as accurately as you can, the time
(in GMT) when each item or program
was heard. Your report should cover a
15 to 30 minute period or longer.
You may be wondering where to address your reports to shortwave stations. Two books that will be of help
in providing the addresses of SW stations are World Radio TV Handbook
and the SWL Address Book. The former is available from Gilfer Associates
Inc., Box 239, Park Ridge, NJ 07656,
and Billboard Publications, One Astor
Plaza, New York, NY 10036. The latter
is available from Gilfer Associates Inc.
An Alternative to QSL'ing. Collecting
QSLs from stations you hear can be a
lot of fun. For many people it is a thrill
to find a card or letter from a station
half way around the world in their mailbox. There is one drawback to collecting QSLs from stations you hear. It can
be rather costly!
Airmail postage to most foreign
92
equivalent, the process is referred to as coding. The
pure binary code is one of many binary codes.
8. Binary coded decimals are easy to use. To represent
a decimal number as a binary coded digit (BCD) the
appropriate 4 -bit code of pure binary numbering is substituted for each of the decimal digits. Advantages to
this system is that it is a good compromise between men
and machines, it is easy to learn and simpler than pure
binary. However, it is much less efficient than pure binary. Circuits using it must be more complicated, less
eficierit, and more prone to time delays.
9. The Gray Code is a widely -used system. Only one bit
changes from one number to the next one in sequence.
It minimizes errors in electronic circuitry when it
changes from one state to the next. However, it is quite
difficult to use in arithmetic computations.
10. ASCII is the microcomputer, data-processing, alphanumeric code. Basically a binary system, it can represent
alphanumeric characters through a variety of binary
systems using six, seven, or eight bits.
11. Parity is the check bit, the last bit in a seven or eight bit ASCII code. It is there to determine 1f the data has
been sent correctly. There is even and odd parity but
both accomplish the same end.
12. BAUDOT code is the ancestor of ASCII. It is hardly
in use anymore. It is a 5 -bit code and so can only represent 32 characters. Whether a given code represents a
letter or a figure must be inputed at the keyboard of
the terminal.
countries is 31 cents per half ounce.
A reception report could take one or
two units of postage to mail, 31 or
perhaps 62 cents. Next, there is the cost
of incidentals, important incidentals
such as stationery and envelopes.
It is generally considered proper to
include return postage in your report
to a station. Some listeners don't, but
your odds of getting a reply from the
stations increase if you do. U.S. postage
stamps are of no value in mailing a
reply from overseas. But mint (unused)
stamps from foreign countries can be
purchased from stamp dealers or from
the DX Stamp Service, 83 Roder Parkway, Ontario, NY 14519. It is also possible to purchase International Reply
Coupons at your post office for 42
cents each. These are exchangeable
overseas for sufficient postage to send a
reply via seamail. Several IRCs are required for an airmail response.
Tape it. One way to beat the cost is to
forget about collecting QSLs from the
stations. Instead, tapè record the stations you hear. Not only do your tapes
provide the reception proof, they also
can be fun to listen to-or play for
friends-next week, next month, next
year. Tape recordings can let you relive the excitement of hearing a certain
station for the first time.
Do some experimenting yourself
when it comes to taping your DX
catches. But here are a few tips. Rather
than using a microphone to pick up the
sound from the receiver's speaker, use
a "patchcord" from the headphone jack,
or external speaker terminal of your re-
ceiver through an attenuating patch
cord to the recorder. Don't record long
segments of each station, just a minute
or so that includes the station's announced identification. Use a reel-toreel recorder if you can, since it allows
you to splice and edit your tapes easier
than using a cassette model.
Save some money and have some fun
by recording your DX on tape!
Band Sweep. Times in GMT, frequencies in kilohertz. 1,295-Trans-Atlantic
medium wave DX is possible, particularly for those listeners on the eastern
seaboard. The British Broadcasting
Corp. outlet at Crowborough was reported as heard with a good signal on
this "split" frequency between U.S. stations on 1290 and 1300 kHz, at about
0430. 6,010-Italy's RAI in Rome transmits in English to North America at
0100 on this frequency, 9,022-Iran is
a country that quite a few SWLs haven't
added to their log book. The Voice of
Iran in Teheran can be heard in English
at 1930 on this out-of-the-way frequency. 9,650-FEBA, the Far East
Broadcasting Association, operates from
a rather exotic Indian Ocean spot, the
Seychelles islands. You can find it signing on in English at 0315. 15,120-A
solid African signal is heard from the
Voice of Nigeria at Lagos, Nigeria, at
1800 in English. Credits: Mark Connolly, MA; W. Noel Brown, MI; Bill
Sandborn, TN; Kenneth Earhart, PA;
Roland Desrosiers, MA; National Radio Club, P.O. Box 3125, Louisville, KY
40232; North American SW Association P.O. Box 13, Liberty, IN 47353
ELEMENTARY ELECTRONICS/July-August 1978
LITERATURE
LIBRARY
their do-ityourself kits and factory assembled electronic
equipment,
Specialties, are test
equipment.
burglar/fire alarms, hobbyist and auto electronics.
302. International crystal has illustrated folders containing product information on radio communications kits for experimenters (PC boards; crystals;
transistor RF mixers & amplifiers; etc.).
303. Regency has a new low cost/high performance
UHF/FM repeater. Also in the low price is thei,
10 -channel monitoradio scanner that offers 5 -band
801. Get the '78 Eico Catalog and see
performance.
304. Dynascan's new B 8 K catalog features test
equipment for industrial labs, schools, and TV
servicing.
306. Get Antenna Specialists' catalog of latest mobile antennas, test equipment, wattmeters, accessories.
308. Compact is the word for Xcelite's 9 different
sets of midget screwdrivers and nutdrivers with
"piggyback" handle to increase length and torque.
also.
A handy show case serves as a bench stand
310. Turner has two catalogs on their CB microphones and antennas. They give individual specifications on both lines. Construction details help in
your choice.
311. Midland Communications' line of base, mobile
and hand-held CB equipment, marine transceivers,
scanning monitors, plus a sampling of accessories
are covered in a colorful 18-page brochure.
312. The EDI (Electronic Distributors, Inc.) catalog
is updated 5 times a year. It has an index of manufacturers literally from A to X (ADC to Xcelite).
Whether you want to spend 29 cents for a pilot light socket or $699.95 for a stereo AM/FM receiver,
you'll find it here.
313. Get all the facts on Progressive Edu-Kits Home
Radio Course. Build 20 radios and electronic circuits; parts, tools, and instructions included.
318. Get the Hustler brochure illustrating their complete line of CB and monitor radio antennas.
318. GC Electronics offers an "Electronic Chemical
Handbook" for engineers and technicians. It is a
"problem solver" with detailed descriptions, uses
and applications of 160 chemicals compiled for
electronic production and packaging. They are used
for all types of electronic equipment.
320. Edmund Scientific's new catalog contains over
4500 products that embrace many sciences and
fields.
321. Cornell Electronics' "Imperial Thrift Tag Sale"
Catalog features TV and radio tubes. You can also
find almost anything in electronics.
322. Radio Shack's 1978 catalog colorfully illustrates their complete range of kit and wired products for electronics enthusiasts -CB, ham, SWL,
hi-fi, experimenter kits, batteries, tools, tubes, wire,
cable, etc.
323. Get Lafayette Radio's "new look" 1978 catalog
with 260 pages of complete electronics equipment.
It has larger pictures and easy -to -read type. Over
18,000 items cover hi-fi, CB, ham rigs, accessories,
test equipment and tools.
327. Avanti's new brochure compares the quality
difference between an Avanti Racer 27 base loaded
mobile antenna and a typical imported base loaded
TV kits, National Schools has 10 from which to
choose. There is a plan for GIs.
333. Get the new free catalog from Howard W.
Sams. It describes 100's of books for hobbyists
and technicians -books on projects, basic electronics and related subjects.
334. Sprague Products has L.E.D. readouts for those
who want to build electronic clocks, calculators,
etc. Parts lists and helpful schematics are included.
335. The latest edition of the TAB BOOKS catalog
describes over 450 books on CB, electronics, broadcasting, do-it-yourself, hobby, radio, TV, hi-fi, and
CB and TV servicing.
338. "Break Break," a booklet which came into
existence at the request of hundreds of CBers, contains real life stories of incidents taking place on
America's highways and byways. Compiled by the
Shakespeare Company, it is available on a first
come, first serve basis.
Royce Electronics has a new 1978 full line
product catalog. The 40 -page, full -color catalog
contains their entire new line of 40 -channel AM and
SSB CB transceivers, hand-helds, marine communications equipment, and antennas and accessories.
342.
344. For a packetful of material, send for SBE's
material on UHF and VHF scanners, CB mobile
transceivers, walkie-talkies, slow-scan TV systems,
marine -radios, two-way radios, and accessories.
345. For CBers from Hy -Gain Electronics Corp. there
is a 50 -page, 4-color catalog (base, mobile and
marine transceivers, antennas, and accessories).
Colorful literature illustrating two models of monitor-scanners is also available.
353. MFJ offers a free catalog of amateur radio
equipment-CW and SSB audio filters, electronic
components, etc. Other lit. is free.
A government FCC License can help you
a career in electronics. Send for Infor-
354.
qualify for
mation from Cleveland Institute of Electronics.
355. New for CBers from Anixter-Mark is a colorful
4-page brochure detailing their line of base station
and mobile antennas, including 6 models of the
famous Mark Heliwhip.
Continental Specialties has a new catalog
featuring breadboard and test equipment for the
professional and hobbyist. Descriptions, pictures
and specifications aid your making a choice.
356.
359. Electronics Book Club has literature on how to
get up to 3 electronics books (retailing at $58.70)
for only 99 cents each
plus a sample Club News
...
package.
361. "Solving CB Noise Problems" is published by
Gold Line and tells you how to reduce the noise
and get a clearer signal. In discussion and dia-
gram you can find out about the kinds of noise,
their sources, and the remedies.
362. B8F Enterprises' Truckload Sale catalog of-
fers 10% off all merchandise: (military or industrial surplus) speaker kits, TV games, computer
terminals, tools, TV components, lenses, and more.
363. Send for computer enterprises' catalog of
microcomputer systems for personal, business, educational and industrial users. They claim the greatest bargains in microcomputer equipment, systems,
parts and supplies.
364. If you're a component buyer or specifier, you'll
want this catalog of surplus bargains: industrial,
military, and commercial electronic parts, all from
Allied Action.
365. Electronic Supermarket has a new catalog of
almost everything in the field -transformers, semiconductors, tv parts, stereos, speakers, P.C. boards,
phones, wire and cable, tools, motors.
for Poly -Packs' new catalog featuring
hundreds of bargains: new Barrel Pack kits, hobby
computer peripheral parts, fiber optics, solar energy chips, digital clocks, and more.
367. Optoelectronics' new catalog features their
new Frequency Counter, a 6-digit clock calendar
kit, mobile LED clock, biorhythm clock, digit conversion kit, and many others.
366. Send
Electrical Products has a handbook
describing their new "PRO" keyboard for personal
computer, hobbyist and OEM users. Included are
instructions on how to customize it on -the -spot,
schematics, charts, and diagrams.
368. Cherry
369. Motorola Training Institute offers a brochure
on two new home -study courses: Four lessons
cover semiconductors, designed for all technicians
servicing electronic equipment; the 34 -lesson professional FM two-way radio course is for those
planning to service land -mobile equipment.
370. The 1978 catalog from Computer Warehouse
has data on 10 different microcomputers, with used
peripherals, and available for immediate delivery.
Over 1,500 products are covered, new and used,
from over 170 different vendors.
371. Your computer system needn't cost a fortune.
Southwest Technical Products offers their 6800
computer complete at $395 with features that cost
you extra with many other systems. Peripheral bargains are included here.
"Erector
Kit" Computer System; also their factory wired ver-
372. See how you can save with Olson's
sion which Includes a 2 -volume Bell & Howell
instruction course. Send for information.
i
ELEMENTARY ELECTRONICS
Box 1849, G.P.O.
New York, NY 10001
JULY/AUGUST 1978
Void After December 15, 1978
Please arrange to have the literature whose numbers I have circled below sent to me as
soon as possible. I am enclosing 500 for each group of 10 to cover handling. (No stamps,
please.) Allow 4-6 weeks for delivery.
antenna.
301
302
303
304
306
308
310
311
312
313
316
318
320
321
322
323
327
328
329
330
331
332
333
334
335
338
342
344
345
353
354
355
356
359
361
362
364
365
366
367
368
369
370
371
372
328. A new free catalog is available from McGee
Radio. It contains electronic product bargains.
329. Semiconductor Supermart is a new 1978 catalog listing project builders' parts, popular CB gear,
and test equipment. It features semiconductors
all from Circuit Specialists.
330. There are nearly 400 electronics kits in Heath's
new catalog. Virtually every do-it-yourself interest
is included -TV, radios, stereo and 4-channel, hi-fi,
hobby computers, etc.
331. E. F. Johnson offers their CB 2-way radio catalog to help you when you make the American vacation scene. A selection guide to the features of the
various messenger models will aid you as you go
through the book.
332. If you want courses in assembling your own
-
363
300
Enter my subscription to Elementary Electronics for 9 issues at $5.97.
H8G018
Check enclosed. Add $1.013 for Canada and all other countries.
NAME (print clearly)
ADDRESS
L
ELEMENTARY ELECTRONICS/July-August 1978
CITY
STATE
ZIP
J
93
Classified
mmomum....
IVIARKET
-is
ELEMENTARY ELECTRONICS
.published Bi -monthly. The rate per word for CLASSIFIED ADVERTISEMENTS is
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WANTED. ASSEMBLE ELECTRONIC DEVICES IN
YOUR HOME. Get started in apare time. Experience,
Knowledge or Investment not Necessary. Expect big
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START Your own Burglar Alarm Business. High
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MONEY IN OIL PAINTINGS. Three highly profitable methods -open an art gallery. Run in home art
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EXCELLENT second income working at home. Free
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NEW!!! POCKET EXERCISER -Easy use.
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LIFETIME GUARANTEE!!! Order NOW -get FREE
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AUTOMOBILES & MIDGET CARS
TWENTY car saver formulas helpful hints to save
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RECEIVE mail galore! National listing $1.00.
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$2,000« Monthly selling Information by mall. Free proof! Associates, Box 123-L,
Wenonah, NJ 08090.
BORROW $25,000 interest free! Indefinitely! Any Free booklet! Fay's 484E N. Main, Kalispell, MT
Many Freel
Liquidations
Closeouts
. Job Lots
Single Samples. Free Details. Worldwide Bargain hunters, Box 730 -IO, Holland, MI 49423.
ELECTRONICS Surplus plus more. Free Catalogue
Stateside, P.O. Box 805, Oakpark, IL 60303.
-
DETECTIVES
INVESTIGATORS' MANUALS: Electronic surveillance, lock picking, etc. Write: Mentor. Dept. 5,
145-53 No. Blvd., Flushing, NY 11354.
DO IT YOURSELF
MARE YOUR CLASSIFIED AD PAY. Get "Haul to
Write A Classified Ad That Pulls."
cate worth $2.00 towards a classified
cation. Send $1.50 (includes postage)
Davis Publications, Inc., Dept. CL,
South, New York, NY 10003.
Includes Certifi-
ad in this publito R. S. Wagner,
229 Park Avenue
ENGRAVING PENCILS protects aaginst loss, theft.
Mark CB's radios, camping and sports equipment.
Rush $2.98 plus 500 handling. Phelps, 229 Cedardale,
King, NC 27021.
REPAIR COLOR TV'S. ANYONE Can. New Easy
method. Details Free. Publications, Box 517A, Brea,
BOOKS & PERIODICALS
BUSINESS OPPORTUNITIES
60649.
74404.
BLUEPRINTS. PATTERNS & PLANS
CBer's! Personalized CB decal with a 1 -year subscription to Elementary Electronics only $3.97. E/E,
the magazine that covers CB and all areas of radio
communication. Send check: Elementary Electronics.
Decal Dept., 380 Lexington Ave., New York, NY 10017.
FREE Catalogs-Discount Paperbacks-Gambling Systems. Destiny, Box 366-R, Roundlake, IL 60073.
$350
$60 hundred addressing envelopes. Guaranteed earnings. Rasmussen, DP78, 1747 N. 450 E., Ogden, UT
NEW CRAFT -PRINT CATALOG -Choose from over
100 great easy -to -build plana. Send 81.25 (completely
refunded with your first order). BOAT BUILDER,
(CP Div.) -380 Lexington Ave., New York, NY 10017.
WHAT'S going on in housing? Get advice on how
to economize in modernizing or improving or adding
space from idea to completion. Working blueprints
available. Send $1.50 (includes postage) for 110 Better Building Ideas to: Davis Publications, Inc., 380
Lexington Ave., New York, NY 10017.
Huntington, WV 25705.
8127,
CA 92621.
PLEASE Be sure to include your zip code when
ordering merchandise from classified advertisements.
You'll receive faster delivery.
PHOTO mug -photo button machines. Brochure.
Sample button $1.00, Write Coffman, 3973M, Glen haven, Abilene, TX 79603.
FOR anyone who wants the satisfaction and economy
of repairing, furnishing and maintaining the furniture
in his home. Send $1.50 to FURNITURE, 380 Lexington Ave., New York, NY 10017.
30-100W Amplifier Kits under $53.00. Free catalog:
Audiovision, Box 955 Stn B, Willowdale,
Ont. M2K
MAIL-ORDER BOOK DEALERS WANTED! Free
Details! Books, P.O. Box 395 B, Excelsior, Minnesota
2T6.
MAKL MONEY, Unique Mailing Program, No Gimwicks, Free Details. Caster, P.O. Box Ill, Wampsville, NY 13163.
ATTENTION-EARTHWORM RAISING STARTER
KIT, 1000 select Hybrid Red Wiggler Breeders,
15 lb.
SOILESS-ODORLESS bedding, raising instructions.
$29.95 post-paid. Lebers Worm Farm, Stillhouse
Road, Freehold, NJ 07728.
EARTHWORMS
55331.
SAVE $25.00 Or More On Postage, Eliminate Unnecessary Time Spent Mailing and Addressing! $2.00
Forwards Your Name and Address to BUSINESS
OPPORTUNITIES, ADDITIONAL INCOME. MONEYMAKING OPPORTUNITIES, Advertisements, this
Issue. G & G MAILING SERVICE, INC., P.O. Box
4676, MANCHESTER, NH 03105.
EDUCATION
USED
Courses!
&
Books!
Marlborough, Salem, MA
INSTRUCTION
Lists 25e SMITH'S,
01970.
124
$3000.00 MONTHLY. Start immediately. Stuff envelopes at , home. Information, send self-addressed
stamped envelope Village. Box 2285-DFG, Irwindale,
GA 30518.
CA 91793.
GET INTO BROADCASTING: Become DJ engineer.
Start your own station, get free equipment,
Free details. "Broadcasting," Box 5516-07E, records.
Walnut
Creek, CA 94596.
MILLIONS in Mail! Free Secrets. Transworld-3,
Box 6226, Toledo, OH 43614.
details,
BIG Profits in becoming a supplier to major industry through electroplating small parts and metalizing nonmetallica. Write for free particulars: Mason,
Room MC -107 -HF, 1512 Jarvis, Chicago, IL 60626.
PROFESSIONAL INSTRUCTIONS -Wall Washing,
Carpet -Window Cleaning, $3.00. Sentry Building
Maintenance, 8615 Florence, Downey, CA 90240.
"HOW TO RECRUIT COMMISSION SALESPEOPLE! Free Details! Success Publications, P.O.
Box 35305, Edina, MN 55435.
stuffing our circulars into stamped addressed envelopes. No liimt. Beginners Kit
$2.00 (Refundable). Collassi -Box 333 -DC, Brooklyn,
NEW Luxury Car Without Cost! Free
CODEX-A, Box 6073, Toledo, OH 43614.
$300.00 MONTHLY.
Start immediately. Stuff en-
velopes at home. Information, send self-addressed
stamped envelope. Village. Box 2285-DFG, Irwindale,
CA 91706.
OPPORTUNITY! Earn at home! Good business.
Free booklet! Way's 484E N. Main, Kalispell, MT
59901.
$180 WEEKLY MAILING circulars. Start immediately. D'Alolsio, 30 Gladys Ave., 57, Mt. View, CA
94043.
$30.00 HUNDRED
NY 11219.
COLLEGE degree by mall, via resume. Education,
256D South Robertson, Beverly Hills, CA 90211.
ELECTRONIC EQUIPMENT & SUPPLIES
HOMEWORKERS-$1000 Weekly mailing criculars!
Stamped envelope: KV Advertising, Box 13283, Ft.
Carson, CO 80913.
FREE CATALOG: Electronic supplies -kits for the
hobbyist. Low prices. Anklam Electronics. 4709 nth.
6th St., Wausau, WI 54401.
BUILD YOUR OWN TV CAMERA. Great for home
and business. Free Illustrated catalog. Phone or
write: 402-987-3771. ATV Research. 13 E. Broadway
Dakota City. NB 68731.
ENVELOPE stuffing
secrets guaranteed!
Wayne, Box 218 -LEG, Poteet, TX 78065.
REPAIR MOTORS! GENERATORS! ALTERNATORS! BUILD TESTERS! Modelectric, Box 7266
Kansas City, MO 64113.
START your own business. No investment. Free
Details. Bargain House Dept. EE, 1407 South Reservoir. Pomona, CA 91766.
Free!
THERE IS NO CHARGE FOR THE ZIP CODE -PLEASE USE IT IN YOUR CLASSIFIED AD
94
ELEMENTARY ELECTRONICS,July-August 1978
'
31.313131.....a.yi
..
PLACE
To
be included in the next issue, pelase send order and, remittance to R. S. Wayner,
ELEMENTARY ELECTRONICS, 380 Lexington Ave., New York, N.Y. 10017
MONEYMAKING
INVENTIONS WANTED
COMPUTER INTERFACE RF MODULATORS. Video
monitors. TV cameras. Free catalog. Phone or Write.
402-987-3771. 13-E Broadway, Dakota City, NE 68731.
B&K test equipment. Free catalog. Free shipping.
Dinosaur discounts. Spaoetron-FG, 948 Prospect, Elm-
hurst.
1L 60126.
WALKIE TALKIE CRYSTALS -We made a great
buy and we want to share it with you! Special!
While they last. All 40 channels available -in stock
transmit and receive -Fits all walkie talkies $2.95
PER PAIR, limited time offer! Monitor crystals $3.95
each. Certified check or money order. C.O.D. ok plus
-
postage and charges-ROLIN DISTRIBUTORS P.O.
Box 436, Dunellen, NJ 08812. 201-469-1219.
EMPLOYMENT INFORMATION
hiring nationwide.
. Stations
RADIO-TV Jobs
Free details: "Job Leads," 1680 -HC Vine, Hollywood,
CA 90028.
FOR THE HOME
PRACTICAL tips for home, garden and workshop
can be found in "1001 How -To Ideas." Send $1.50
for your copy (includes postage) to 1001 How-To
Ideas, 380 Lexington Ave., New York, NY 10017.
GOVERNMENT SURPLUS
-
JEEPS -$59.30 -CARS -$33.501 200,000 ITEMS
GOVERNMENT SURPLUS -MOST COMPREHENSIVE
DIRECTORY AVAILABLE tells how, where to buy
MONEYBACK GUARANTEE.
YOUR AREA
$2.00
Government Information Services. Department E7,
Box 99249, San Francisco, CA 94109 (433 California).
-
-
Classified
Samples.
98499.
WIN $5,000.00 in monthly free contest. $5 enrollment enters you full year! Contests, 2830DG-Gaffey,
San Pedro, CA 90731.
MAKE Millions in mail order. Information, tips.
$1.00 to Lamron Ltd., Box 299C, Institute, WV
25112.
$180.00 WEEKLY Mailing Circulars. Start immediately. Everready, 422A Clermont Ave., Brooklyn,
NY 11238.
BECOME Wealthy And Independent in Mailordering. A Complete Book that Tells All. John Tabor's
GOLDEN MONEY MAKER, 100% Guaranteed, only
$10.95. Box 90370, LA, CA 90009.
MAKE YOUR CLASSIFIED AD PAY. Get "How to
Write A Classified Ad That Pulls." Includes certificate worth $2.00 towards a classified ad in this publication. Send $1.50 (includes postage) to R. S. Wayner, Davis Publications, Inc., Dept. CL, 380 Lexington Ave., New York, NY 10017.
$2,000 monthly possible stuffing envelopes! Send
stamped self-addressed envelope! Craft. Box 2230 D,
Oceanside CA 92054.
EARN $1000 MONTHLY -Unique Mailing Program!
Guaranteed!! FREE DETAILS-L.O.E., Box PD -06180,
Portland, OR 97206.
STUFF ENVELOPES, $250 per thousand. Free Supplies. Rush stamped addressed envelope. L/L Enterprises, Box 226D, Danville, AL 35619.
HYPNOTISM
FREE Fascinating Hypnosis Information! Startling!
DLMH, Box 467, Anaheim. California 92805.
INVENTIONS WANTED
IDEAS, inventions, new products needed by innovative manufacturers. Marketing assistance available
to individuals, tinkerers, universities, companies with
feasible concepts. Write for Kit -EE, 12th Floor.
Arrott Building, Pittsburgh, PA 15222.
JEWELRY
S.S. Turquoise Indian Jewelry at the lowest prices
available anywhere. Free brochure. ß&W Turquoise
Company, P.O. Box 1230-U. Las Vegas, Nevada. 89101.
702-386-5060.
MAGNETS
MAGNETS. All types. Specials -20 disc, or 10 bar,
or 2 stick, or 8 assorted magnets. $1.00. Magnets,
Box 192-E, Randallstown, MD 21133.
MAIL-ORDER OPPORTUNITIES
MAILORDER Secrets to Success. Everything Included, Free. G. J. Ent.. 8700 N. Merlil, Niles. IL
60648.
information by
mail.
$1,000 MONTHLY selling
FREE details. Valentine, Box 6381, Gt. Falls MT
59406.
MISCELLANEOUS
PRINTED Circuit Boards from Sketch or Artwork.
Free Details DANOCINTHS, Box 261 Westland, MI
48185.
WIN AN ELECTRONIC WORKSHOP! Plus instant
prizes! R.T.T.'s New Accelerated Radio & T.V.
course. Radio Television Training, P.O. Box 279-E-56,
Syracuse, NY 13206.
WILLS. Outline for preparing your own. Legally
binding. $2. HolRil, P.O. Box 805, Atlanta, GA 30301.
WE may have what you need so send for free catalog. Joan Ellen's Friendly Shoppe, Dept. 35F, Newark -Pompton Tpke., Pequannock, NJ 07440.
MONEYMAKING OPPORTUNITIES
$250.00
profit/thousand possible-stuffing -mailing
envelopes. Offer: Rush stamped addressed envelope:
Universal -ADVS X16180 Fort Lauderdale, FL 33318.
$500 thousand stuffing envelopes. Free details. Rush
self stamped envelope. R. Mognet Co.. Box 449D,
Warren, OH 44482.
PERSONAL-Cont'd
OPPORTUNITIES-Cont'd
Profits: Mailing Circulars Free
Grahamco, DPBX 99371, Tacoma, WA
FANTASTIC
OF INTEREST TO ALL
$1,000.000. 'YOU can become millionaire overnight.
Eastern States Lotteries. Details free. Send addressed, stamped envelope, Eastern. Box 262-F,
Salem, NJ 08079.
OLD GOLD WANTED
BUYING GOLD, silver, platinum, any form!
Jewelry, sterling, coin, industrial. Prompt appraisal
and payment. Your approval guaranteed. American
Metallurgy Company, P.O. Box 33009, Charleston,
SC 29407.
PEN PALS
JOIN North America's leading penpal club. Details
from Friends Worldwide CP-95/F Anjou, Montreal,
H1K 435.
PERSONAL
NEW Luxury Car Without Cost! Free
Codex -CC, Box 6073, Toledo, OH 43614.
telephone conversations privately -automatically. Leave recorder unattended. Robert's, Box
495M, Parkridge, IL 60068.
FREE: 1,000 LADIES PHOTOS. World's largest
Matrimonial Catalog. Postage/Handling $1.00. Inter contact, Box 12, Toronto, Canada M4A 2M8.
BEAUTIFUL MEXICAN GIRLS! Friendship, marriage! Photos, information Free. "Latins," Box 1716E. Chula Vista, CA 92012.
JAPANESE introductions! Girls' photographs, descriptions, brochure, details, $1.00 INTER -PACIFIC,
Box 304 -SC, Birmingham, MI 48012.
SWEDISH women travelling country! All cities,
towns, Details, photos $1.00. Ingrid, 2520 N. Lincoln,
Suite 255-A, Chicago 60614.
PHOTOGRAPHY -PHOTO FNISHING
RECORD
&
and instructions. A must for successful photography
in your darkroom. Order direct: 8 & M Instruments.
Dept. EE7. 380 Lexington Ave., New York, NY 10017.
RADIO & TELEVISION
TV TUBES 36# each. Send for Free 48 page color
catalog. Cornell, 4217-W University, San Diego, California 92105.
BUILD Distance Crystal Sets. 10 plans -250;
Handbook "18 Different" -50t; "20 Different" -50e.
Catalog-25t, refundable. Laboratories, 1477-G, Gar-
den Grove, CA 92642.
BROADCAST STATION: Operate from home,
school, church. Receive free tapes, records. Learn
details! Broadcasting, Box 5516 -GA, Walnut Creek.
CA 94596.
SHORTWAVE DXers! Reception report sheets and
postcards now available 4x6 inches. Large space for
program details and all information needed for QSL.
Pad of 30-1.00. Postcards -.10 each. Minimum order:
200. RAB, Box 386, North Myrtle Beach, South Carolina 29582.
"DISTANCE One Tuber" Handbook -50t. 15 Distance one tube plans-25#. Catalog 25# refundable.
Laboratories, 1477-G, Garden Grove, CA 92642.
LINEAR AMPLIFIERS, 25-100 watt solid state.
OMNIPOLARIZED BASE ANTENNAS. Portable/mobile/memory/300 MHZ FREQUENCY COUNTER.
Construction plans: $3.00 each, 3/$7.50. Specify frequency band! Kits available. Free catalog! PANAXIS,
Box 5516-05E, Walnut Creek, CA 94596.
TUBES Oldies, latest. Supplies, components, schematics. Catalog free. (Stamp appreciated). Steinmetz,
7519 -EE Maplewood, Hammond, IN 46324.
Details.
DATES GALORE! Meet singles -anywhere.
DATELINE, toll -free (800) 451-3245.
Call
ADULT pleasure products-over 600 items! Giant
catalog $1.00. Clifton's, D-1068, Saugus, CA 91351.
DO YOU KNOW "How to Write a Classified Ad
That Pulls" includes a certificate worth $2.00 toward
a classified ad in any of our publications? For your
copy send $1.50 (includes postage) to R. S. Wayner,
Davis Publications Inc., Dept. CL. 380 Lexington
Ave., New York, NY 10017.
BEAUTIFUL GIRLS from all continents want correspondence, friendship, marriage. Sample photos
free. Hermes -Verlag, Box 110660/D, 1000 Berlin 11,
Germany.
IMPOTENCE problems? Lack zip? Helpful new
report -Free! Reliance-EE2, Box 5157, Santa Monica,
SUPPLIES
SAVE HUNDREDS OF DOLLARS!!! Make your own
S & M Densitometer. Send $3.00 for detailed drawings
RUBBER STAMPS
RUBBER stampa made. Three lines 63.75. Rubber
Stamps, B1337 -E8, Waldo, AR 71770.
SCIENCE & CHEMISTRY
Spectacular novelties, simplified
manufacturers textbook, $5.00. Guaranteed. Tropic,
Box 95M4, Palm Bay, FL 32905.
FIREWORKS.
SELF-IMPROVEMENT
YOU ARE WHAT YOU EAT -the key to losing
weight. An easy diet plan for you. Suggested Menus
for the week, easy lunches to eat out, special recipes
for $1.50. Eleanor Albert, 24641 Parklawn, Oak
Park, MI 48237.
SONGWRITERS
SINGLE? Widowed? Divorced? Nationwide introductions! Identity, Box 315 -DC, Royal Oak, MI 48068.
SONGWRITERS: Exciting offer -poems eons. needed -Free evaluation -Creative Music Productions, Boa
1943-A7, Houston, TX 77001.
THERE IS NO CHARGE FOR THE ZIP CODE.
PLEASE USE IT IN YOUR CLASSIFIED AD.
JAPANESE Girls Make Wonderful Wives. We have
large number of listings. Many interested in marriage. Only $1.00 brings application, photos, names,
descriptions, geustlonaire, Etc. Japan International,
Box 156 AA, Carnelian Bay, CA 95711.
GET World's Biggest Wholesale Import Merchandise Catalog. Details Free. Worldround-P. Medina.
CA 90405.
BEAUTIFUL Mexican -Oriental girls Needing American Boy -Friends. Free Details "actual" photos.
World, Box 3876 -DC, San Diego, CA 92103.
"DATE WITH DIGNITY" Professional Matching.
Drawer 6765, Fort Worth, 76115 (817) 921-0281.
START YOUR OWN BUSINESS
WA 98039.
WATCHES. WATCHMAKING & REPAIRING
WATCH and clock repairing books, tools, materials.
Free catalog. North American, Box 77, EE43, Fox
River Grove, IL 60021.
THERE IS NO CHARGE FOR THE ZIP CODE -PLEASE USE IT IN YOUR CLASSIFIED AD
ELEMENTARY ELECTRONICS/July-August 1978
95
Love That Lettering
(Continued from page 63)
with a brush -on spray coating. It's best
to use products made for this specific
purpose, which should be available from
the same sources as the rub -on lettering. Ordinary lacquers, clear fingernail
polish, etc., are likely to damage the
lettering. Always make a test beforehand or you may end up with an ugly
mess.
Here are some additional suggestions:
1) Read the instructions (if any)
that accompany the lettering set.
2) If this is your first experience
with rub -on lettering, practice on
scrap material first to get the feel
of it.
3) When applying the lettering,
keep a backing sheet beneath the
part of the carrier sheet that you
are not using. This prevents unwanted letters from transferring
and also keeps the lettering clean.
Dirt or skin oils can interfere with
adhesion.
4) To align rows of letters or words,
tape a strip of paper to the panel
about 1/16-inch below where the
row will go.
5) A word made from individual
letters can be centered by starting
in the middle and working outward to both ends.
6) Applying lettering in cramped
spaces, such as on assembled
equipment, can be made easier by
cutting up the carrier sheet.
7) Rub -on lettering is also useful on
meter scales and printed circuit
artwork or boards.
Newscan
(Continued from page 27)
tion generated inside the lamp. The
white light of a fluorescent lamp is produced by combining different phosphors into a mixture that emits a spectrum of colors of visible light, such as
red, green, or blue. GE's energy -saving
Watt -Miser II lamp utilizes a highly
efficient combination of phosphors. Es -
ELEMENTARY ELECTRONICS
INDEX TO ADVERTISERS
RS#
-
30
25
5
22
--
6
28
42
43
2
35
9
34
11
12
1
13
14
41
-
ADVERTISER
AMC
Aldelco
Avanti
B & F Enterprises
8 & K Precision
Barta
CFR
CIE
Cobra
Continental Specialties
Delta Electronic Co.
Digi-Key Corp
Eico
Electronics Surplus Supply
Electronic Systems
Extron Life Screens
E V
Game
Gilfer
Godbout
Heath Co.
Information Unlimited
International Crystal
Kester Solder
Locksmithing
McGee
24
McKay Dymek
Meshna
39
44
Moonlighter
Non Linear
Non Linear
19
-
20
16
15
NRI
NTS
OK Machine & Tool
84
23
10
14
83
13
26
25
23
26
25
14
88
25
26
26
18.21
28 391
86
Progressive Edu-Kit
Proyecta-Pix
Radio Shack
Radio Shack
Sabtronics
26
21
Southwest Technical
Tab Books
36
38
Trionetics
Vector
96
86
83
16
26
85
President
8
CV3
Polypaks
17
45
29
8
86
12
26
25
4-7
3
Page Digital
23
-
88
Yeasu
CV2
11
16
CV4
87
251
27
27
24
(Continued from page 36)
and sunlight are best. The trouble with
fluorescents is that their light output is
intensity -modulated at 120 Hz., which
is equivalent to 7200 RPM. Depending
upon the exact characteristics of the
fluorescent lamp and its distance from
the photo -probe, erroneous readings can
result from the use of such sources.
There are basically two different ways
of using a photo -tachometer; the choice
of method depends on whether or not
the rotating object can chop a beam of
light. Consider first those devices which
can chop a light beam, such as fans,
propellors, pulley spokes, and even drive
chains. With these yoú simply place the
rotating object between the light source
and photo -probe, thus allowing the propellor or whatever to chop the light that
falls on Ql. Start with a distance of
about six feet between your light source
(100 -watt lamp plus reflector) and the
photo -probe. Decrease the spacing until you obtain a steady indication on
Ml. Further decrease in distance will
not affect this reading. Make note of
this working distance for future reference. Of course, if you are using sunlight, the above directions don't apply.
Note that if the propellor has two
blades, your reading on Ml will be
twice the actual speed of rotation. Likewise, four blades yield a reading that is
four times too high, and so on. Do not
use any backlighting (light coming from
probe side of what you're measuring.)
The other mode of operation relies
on reflection to supply light pulses to
Q1. We have diagrammed a dark colored wheel, to which a small piece
of aluminum foil has been attached.
Once every cycle, the foil is in a position that enable it to reflect light from
the source onto the photo -probe. Measurements by reflection may tend to be
tricky, since you have to set up the
angles just right. Nevertheless, a little
experimentation is usually all that's
necessary to get things working. The
total light path-from source to reflector
to photo-probe-should be less than or
equal to the working distance you determined for the previous case with the
propellor. Sometimes stray reflections in
this mode can be troublesome, since
they may prevent Q1 from cutting off
(i.e., ceasing to conduct). A careful
elimination of all extraneous sources of
reflection will solve this problem.
As a final observation, note that
Mack the Tach is a very flexible measuring instrument; its applications are
limited only by your own ingenuity. So,
when you come upon a measuring task
that has not been described here, don't
be afraid to experiment!
u
.
PAGE
83
Mack the Tach
The two ingredients of
a new phosphor
credited with improved fluorescent lamp
efficiency are examined by Dr. William
Piper of GE's Research and Development
center. The resulting lamps produce more
light from less watts to save energy.
sentially, GE scientists found a practical way of eliminating the deep blue
and red colors that are usually produced by fluorescent lamp phosphors.
Human eyes are relatively insensitive to
those colors. Energy saved by GE's removal of the deep blue and red colors
is then used in more effective parts of
the color spectrum, with a resultant increase in lamp efficiency. For example, GE's new Watt-Miser II lamp
produces 86 lumens per watt (LPW).
By contrast, GE's original Watt -Miser
lamp, introduced three years ago, produces 80 LPW, while its 40 -watt Main lighter fluorescent lamp produces 77
LPW.
Next time you shop at a supermarket,
add up the running feet of fluorescent
lamps and multiply by ten watts. You'll
agree that a 14% power savings will
save a lot of money and fuel.
ELEMENTARY ELECTRONICS/July-August 1978
FREQ. OUI
CSCsdone tagain
Broken tha price and perfornaice Lair ems withnew MAX -1 OC.
The null mode, professional pole Lie fequ nc,r counter that gives /cu
note range wsibili:y accuracy anc
versatilitethan any comparable Ln t
at anywhere rear its low, low price.
MAXimum per`ormance.
MAX-10:isazin h o use. Itgives
yet. canfeois readings from 2311z
toaçrt.ararrte diOe WHz, with 8cig tacccra: =ast readings witf
1,6-sec. pdate and 1 -sec. samFling
rate. =lose se readings, derived from a
crystal-con -idled time base with
3ppn accu-acy. Hig--sensitivity
readings -ran signa s as low as 20
nV. wi:h iicce overload protection
Lp tc 20C V peaks.
hpt_tsizralsover 100MHz au-onaticall flash the rr ost significan:
c igit_ And to inc icate ow -battery con c non ari exteic remaining battery
fe, the emtfredisolal flashes at 1 HL.
I
MAXin urn versatility. Whereverartdwteneier you reed accurate
f eql e -1c readings, MAX can do the
ti
h slip Lad cable supwi io antenna. Or low -loss
tap with UHF :onnectors.=or
A1/1cr =1.1; CB: ham,nusiness racice
and WC :-ans-nitterpr receiver a ign-
job. Use
pliec.
wi
r-en-. Monitoring au_io and RF generatcrs. C hec< ng computer clocks
andothendiçital circuits. Repair of
depth soLiders aid fisi spotters.
TroJbleshoo-ing t_Itrascenic remote
controls. For:hese, and hundreds oother app cations, youll find it ndisperrsable-
MAXinum visibility. MA} -10)
fea.jres aDig, bright 0.6" multiplexes
8-C'gitLED display, with leading -
zen blanl-ing. So 'ou dDn't have to
sgt-int, or so -k upclose. And, MAX's
flip -up sta'ic is
Milt-ire..
MAXiknum fkexibiity. MAX -10)
operates t-on foe pover sources, -c r
use in label field. nterral alkal ne or
NiCad ba-:eries.110 or220V with
charger/errinatcr. 124, with at_tomotile cigarette-ighte- adapter/
charger. Pad exte nal 7.2-10Vsipply
MAXinum value. With all its
impressive specs you'd expec: MAX:
to cost a lot more tan a low $134.9E,
conplete wi-h clip-leac cable and
applications instruction manual. But
tha's ano-3er nice thing about MAX:
though it's accura_e enough for lab
use it's wel vvithir the reach of -iobbyi=ts' ani CB -ere' budgets.
Ordeg today. Call 2-03-62z-3103
(EastCoaat) or 415-42--8872 'Wes_
Coast): 9 a.nì.-5 p m. local time. Major
credit cards accepted. Or see your
CSC dealar.'rices sligitly higher
outside
IAA
Spe:ificaliors.
20 Hz to 111')MFz, guarattle3i
Gatetíne: s2c.FescLltion 1 Hz 5.c curacy ± coin:- _ine base'errci Input
Rang
1
1
:
Impe13nce: 1 MlS'.. 5Ep Coop inc AC. Sine
5ü MHz loWave Sensitive 3CnVRMS
ternal Time Ease F-egaencly: 3.5:9545 MH:
crystc asc. Setabi .y: ± 3 ppn á 25C.
Temp-Stahilmy B-Ite-than 0.2 ppn'°3,
e
I
ppm/yeal: Iisalay:
0-50° Max.. %girl:
Eight E" LED cigits:3rti-glarevemir.. Lead zero clanking: ce2 nal point appeer tetwee i
6th arc 7thdicitwh3l rputerceeds I MHz.
OvertLw: wi hsiy-els3ver93,99959E Hz,
most sgnificait 11Ethard) digit Cal es allow
inexusae`100 MF splay
/6-pcorc pis sec. gatetime. Low
Battery Indicator: NiEn powersuFp yfalls
ing readings
updac
:
.
1
1
below.6VDC al crib lash cf 1l-tzra:e.
Flashry display ext 1E batteylit 3odrrer: E.
AA Akaline ortlit aticells (intErra"); a:ernal:
110 or 220/VAC Elirr nabr/charter, lento cigarette chteraWp:er 72-10VCCext supply;
Bat. Charging: -2- 4 -it Size WWI 1.75":
I
5.63"
7.75" (1.45). 1 ß.S0 x 19.E9 c-
e.)
Weight: Less thar I-511. (0.68 kg- vsbatteries.
Accessories nclurei Clip- end inlet cable
manu3
CONIENTAL SPEAIES COIPc.T_AiION
70 Fulbe Terrace_Box -112 new Hawn Cr 35509
203-624 3103 TeX X11 -63.-227
WEST COAST: 35 Call cru; et., San Franci:a. CA 94104,
415-421 8872
TN(
9111
Z72-:992
GREAT11111AIN: SSCIN_T)Spur Read, North =elbbar Tracing Estate
Felthare, Middlesex, Enganc.
-6181-366í)
01-8911E782 Intl Telex
CANADA Len Finder Le: Cnario
el
CIRC_= 28 Or! READER SERVICE COUPON
Maxell? TDK? Scotch? BASF? Memorex? Ampex? Sony?
Suddenly there's a
new name that eliminates
the confusion (änd ad -fusion):
Could a Radio Shack own -make cassette tape be the greatest
new formula in ferric -oxide 5-step-calendering audio tape?
And isn't it neat that Supertape Gold requires no special bias
settings? Well, we've built the tape, we've compared it in our
labs w -th the summa cum hi-fi brands named above. And now
it's your turn to see if your ears and your tape head confirm our
findings. Fortunately, the price for your experiment is trifling.
If we're right, and Supertape Gold is indeed a breakthrough,
then we both win. You get cleaner sound. And Radio Shack
gets to be your cassette tape company all 6,444 of
our American and Canadian stores and dealers.
'Tis a consummation devoutly to be wished!
-
"I'm Peter Nero. I kid you not.
Supertape Gold is everything they
say it is even though the guy who
wrote the ad is a personal friend."
SUPERTAPEcGOLD. Sold Only at:
A
Division of lándy
'
arpota n, oit Worth
iinn-4-74510e
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