Xtal Calibrator - American Radio History

Xtal Calibrator - American Radio History
OW TO TROUBLESHOOT A PA SYSTE
NOVEMBER- DECEMBER
7
all new
BASIC COURS
Understanding
DC
Series Circuits
Two ICs replace
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48 resistors
GOES IC!
100 -kHz crystal
is accurate
to 0.01%
THIS ISSUE:
/ETWA EXCITING
ALL -IC PROJECTS
ßt7
Mark Ill
Xtal Calibrator
Capacitor zero beats output
against WWV
accurate
stable
low in cost
"Ident" circuitry
pulses output
at 2 --tz rate
-
ZZ
Battery- operated
un.t can also
be powered
witi optional
AC supply
Usable range
extends to
200 MHz
and beyond
25- and 50-kHz
outputs mark
sub -edges of
ham and
SWBC bands
Multi -Purpose Utility Amp
hi- and lo -Z inputs
1
in
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COMMUNICATIONS
This Transceiver
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Communications
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License exam ... To
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COLOR TV, 295
SQ. IN. PICTURE
Included in Color TV
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Building this
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NOVEMBER- DECEMBER, 1969
www.americanradiohistory.com
90037
November /December 1969
Vol. 9 No. 2
elementary
Electronics
Dedicatee to America's Electronics Hobbyists
SPECIAL IC CONSTRUCTION PROJECTS
33
Mark Ill Xtal Calibrator -first of its breed, this all-/C device provides 25 -, 50 -, and
markers way beyond TV's Channel 2
Universal Utility Amplifier- here's a test amplifier with hundreds of practical applications in an all -IC configuration that may well become the hobbyist's standard
100 -kHz
63
PUBLIC ADDRESS EXTRAS
ít
44
49
How to Troubleshoot a PA System- become a PA expert in five easy pages
Quick and Dirty PA System -you'// want to knock this rapid -built PA system together for your church group, lodge, or club
THEORY FOR EVERYONE
37
71
87
Convert Your Darkroom to Color -we tell you how to forget about shades of gray
and make your prints nature's way
What's so Super About Superhets -learn why a circuit developed in 1916 is still
without peer in the entire radio realm
All New Basic Course, Part -all about DC series circuits
I
AS OUR LAB SEES IT
57
69
Heathkit Model GR -681 Color TV Receiver
Allied Model 392 Musical Combo Sideman
COMMUNICATIONS
14
32
83
DX Central Reporting -tune in the Persian Gulf area
Guided Tour -the funny page
Beginner's CPO -buzz off to Morseville and learn while you build
ELECTRONIC CHUNKS AND TIDBITS
43
60
62
68
81
84
Elementary Egotronics -give your id its head
Job Hunting the 1130 Way
1000 -kV Peek -a- Boo -probing the potential-plus in electron microscopes
The Big Push IN Read OUT
The Bug Killers -down with space- traveling micros
Hot News for Your New Flame
DEPARTMENTS
10
11
Cover
Highlights
18
24
23
31
Random Noise -the Editor shoots for the moon
NewScan- picture news that's fit to print
Hey, Look Me Over -your Christmas shopping list
Literature Library -just what your mailbox ordered
En Passant- it's your move
e/e Etymology -electronics what -do-you -call-it
to.R«,r..
mslattary etéo_
__.
%stow
Electronics
o
1M
aaâl WI
t1N$ MOUE,
two E%G11YiG
ltLic pRQl%CtS
Yap. lil
AUTHORS IN THIS ISSUE
Cover photo
by
Leonard
Heicklen
%W 11Metoi
Len Buckwalter-K1ODH, John W. Collins, Lt. Col Eugene.
F. Corlett USAF Ret., Herb Friedman- W2ZLF /KB19457,
-
Webb Garrison, James A. Gupton Jr., Wayné Kiser
WA9VKP, Carl Kohler, Edward Morris- W2VLU, and the
ELEMENTARY ELECTRONICS' Editorial Staff.
MunFPUrpoa UYity lmv
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,rw....
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ELEMENTARY ELECTRONIC
4
www.americanradiohistory.com
Like a better job, more money, a better future?
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In a matter of months, this new ICS course can have
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Build yourself a business in your spare time!
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TV troubles of all kinds, including color!
Complete, practical, makes learning easy and
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329 illustrations show you how to
recognize and identify TV troubles right from the
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Approved by National Electronic Associations.
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ICS
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NOVEMBER -DECEMBER, 1969
www.americanradiohistory.com
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MINI -PROBE
.
.
.
SQUARE -WAVE
GENERATOR
Weighs Less Than
1
Oz.
eiememary
Electronics
Nov. /Dec. 1969
Vol. 9 /No. 2
Dedicated to America's
Entirely Portable
Light Weight
No Maintenance
Required
Minimum Battery Drain
Short Circuit Proof
1
Managing Editor
RICHARD A. FLANAGAN
KQD2566
Technical Editor
CHARLES S. HARRIS
Finish
The Mini -Probe Model 101 is a miniature hand
held transistorized square -wave generator.* Its applications are unlimited in that it can be used to
test transistors and diodes without unsoldering, ideal
for providing transitions in logic circuits, a must for
debugging Audio and RF circuits, and it is a most
useful instrument for general laboratory use. Order
yours today under our unconditional guarantee
against defective workmanship for a period of Iyear from date of purchase.
The output voltage is +1.5 volts at a frequency of
Art Editor and Associate Art Director
JIM MEDLER
Netes Editor
HELEN PARKER
KQD7967
Art Director
JOSEPH A. D'AMATO
Cover Art Director
IRVING BERNSTEIN
Art Associate
MARGARET R. GOTTLIEB
KHZ.
MINI -TRON
Hobbyists
Editor -in -Chief
JULIAN M. SIENKIEWICZ
WA2CQL, KMD4313
Over -Voltage Protection
Hermetically Sealed
Push Button Switch for
Positive Off Position
Non Corrosive Gold
ONLY $995
Electronics
Advertising Director
JIM CAPPELLO
FEASTERVILLE, PA.
Production Director
CARL BARTEE
Production Manager
At home, in your spare time,
Prepare For Your
F.C.C.
GERTRUD BORCHARDT
Assistant Production Manager
MARILYN VARGAS
Circulation and Marketing Manager
ROGER G. CAVANAGH
Instruments Division Manager
WILFRED M. BROWN
LICENSE
We teach you electronics from
the beginning, and then how to pass
F.C.C. license examinations for
your 3rd, 2nd, and 1st class radiotelephone license -all by home
study. This training is approved
under the G.I. Bill. For details,
write:
Dept. E -9
Pathfinder School of Electronics
1509 N. Western Ave.
Hollywood, California 90027
of the Board
G. DAVIS
Chairman
B.
President and Publisher
JOEL DAVIS
Vice- President and General Manager
LEONARD
F.
PINTO
Vice -President and Treasurer
VICTOR C. STABILE, KBP0681
ELECTRONICS is published bi. monthly by
Science & Mechanics 'Publishing Co., a subsidiary of Davis
Publications, Inc. Editorial, Business and Subscription
offices: 229 Park Avenue South, New York, N.Y. 10003.
One -year subscription Tsin issues1 -$4.00; two -year subscription 112 issuesl- $7.00; and three -year subscription
118 issues1-$10.00. Add $1,00 per year for postage outside the U.S.A. and Canada. Advertising offices: New
York, 229 Park Avenue South, 212 -OR 3 -1300; Chicago.
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ELEMENTARY
second -class postage paid at New York, New York and
at additional mailing office. Copyright 1969 by Science and
Mechanics Pubhshinq Co.
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
0g
YOUR MUSIC IN DAZZLING ACTION
MuSic
-
with
"Sidi
Dramatic New Breakthrough
In Audio -Visual Enjoyment
is it light source. If you don't
versatile Edmund 35mm
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All kinds of other uses too -set up to
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Now you can have a thrilling psychedelic
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triple power -rack
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KEEP PACE WITH
THE SPACE AGE!
NEW! LOW -COST COLOR ORGAN
Accompany music with colored lighting that
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Simply plug in 3 11ff. sets of colored light+
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display and home uses -control lighting in
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NEW? PROJECTION KALEIDOSCOPE
At last-a Inw -cost unit complete with interabl
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operated. large screen image at short proljection distance perfect for photo backgrounds,
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RPM 115V Motor,
ight projection. Incl.:
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SOLID Multi -Colored Glass Accessory
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for
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Accepte regular 48" Fluomaintenance.
rescents or Black light Tube listed below.
Adjustable flash (from 4 to 15 per sec.).
Perfect for electrically embellishing disco.
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go -go cages, te. Full length moveable reflector, on-off switch, intensity control, all metal
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Build 56 electronic marvels in minutes-that
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2 to 16 flashes per second. Clear lucite lens
protects long life Xenon lamp -up to 10.000.000 flashes. 60° high lustre reflector
covers 2.000 sq. ft. area -even in dark of
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$89.95 Ppd.
TUNE IN AND TURN ON OUR OWN
Psychedelic Light Show
Takeo a (bookshelf sized o s , alive looking
its
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built -in sicker, an Indio. controlled 3 -channel color organ. Activate by attaching to hiand switch
6 or stereo speaker. Plug
Music fills the room and the prismatic screen
leaps into pulsating life. Patterns are wild
soothing-respondind wonderful, r soft d intensity
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NOVEMBER -DECEMBER, 1969
www.americanradiohistory.com
10 New Exciting Kits For Home & Hobby
...
NEW
NEW Heathkit Solid -State Auto Tune -Up Meter
Measures Dwell, RPM And DC Voltage
The new Heathkit ID -29 is most ver,auile ... really three automotive
Kit ID -29
52995*
test in-
struments in one ... and its low price makes it even a better value. Measures
Dwell on all 4 -cycle 3, 4, 6, or 8 cylinder engines
measures RPM in two
ranges 0 -1500 and 0.4500 ... measures DC voltage from 0 to 15 volts. And no
batteries are needed ... running engine provides both signal and power. Easy
to use ... on both 6 and 12 volt system without changing leads. It's lightweight,
easy to carry ... conies equipped with black polypropylene case that has a
built -in !cad storage compartment and is resistant to virtually everything. Fast,
simple assembly ... takes just one evening. The perfect accessory for the handyman who wants to do his own car tune-up, emergency road service personnel,
or shop mechanics ... order your ID -29 now. 4 lbs.
...
NEW Heathkit Electronic Metronome
The new Ileudtkit I D -17 is a low cost, precise performing electronic Metronome ... a handy helper for any music student. Battery operated
no springs
to wind ... accurate, steady calibration is always maintained
from 40 to
210 beats per minute. Instruction label on bottom gives conversion from time
signature and tempo to beats per minute. Stylish fruit wood finished cabinet.
Easy solid state circuit board construction ... assembles and calibrates in only
2 -3 hours. The new Heathkit TD -17 Electronic Metronome is so low in cost
every music student can afford one ... order yours now. lb.
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NEW
Kit TD -17
S1295'
1
NEW Heathkit 1 -30 VDC Solid -State Regulated Power Supply
NEW
Kit
The new modestly priced IP -28 is an excellent power supple for anyone working
with transistors whether it be in a laboratory or in a home workshop
and
its low price makes it the ideal power supply for classroom use. Compact brown
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with
two voltage ranges 10 v. and 30 v.... and two current ranges 100 mA, I A. External sensing permits regulation of load voltage rather than terminal voltage.
Adjustable current limiting prevents supply overloads and excessive load current.
Convenient standby switch. Fast, easy assembly with one circuit board and
wiring harness. Order yours today. 9 lbs.
IP -28
...
...
s4750*
as
NEW Heathkit GR -88 Solid -State
Portable VHF -FM Monitor Receiver
a
...
Tunes both narrow and snide band signals between 154 -174 MHz
for police,
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with
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order yours today. 5 lbs.
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$4995*
each
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NEW Heathkit GR -98 Solid -State
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Tunes 108 through 136 MHz for monitoring commercial and private aircraft
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perfect receiver for aviation enthusiast ... or anyone who wants to hear the
whole exciting panorama of America in flight. 5 lbs. GRA -88 -1, AC Power
Supply $7.95
NEW Heathkit GR -38 Solid -State AM Clock Radio
NEW
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NEW
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GR -38
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up gradually, and cycles continuously until selector switch is reset. The accurate, dependable clock controls the accessory AC socket so you can have
coffee perking or lights turned on in the morning. The all solid -state radio really
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Kit GD -209A
$14995'
The next best thing to a per,on.d doorman. The "wireless" factory assembled
transmitter operates up to 150 feet away. Just push the button and your garage
door opens and the light turns on ... and stays on until you're safely inside
your hone The giant 7 ft. screw mechanism coupled with the 'I HP motor mean
real power and reliability, and the adjustable spring -tension clutch automatically
reverses the door when it meets even the smallest obstruction ... extra safety
for kids, pets, bikes, even car tops. Assembles completely without soldering in
just one evening. Easy, fast installation on any 7' overhead track door and
jamb & pivot doors with ODA-209-2 Adaptor at $7.95. Order yours now. 66 lbs.
8
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
...
Now There Are 6 Heathkit®
Color TV's To Choose From
NEW Heathkit Ultra- Deluxe "681" Color TV With AFT
Power Channel Selection & Opt. RCA Hi-Lite Matrix Tube
The new Heathkit GR-681 is the world's most advanced Color TV with more
built-in features than any other set on the market. Automatic Fine Tuning on all
83 channels ... power push button VHF channel selection, built -in cable -type
remote control ... or you can add the optional GRA-681-6 Wireless Remote
Control any time
plus the built -in self- servicing aids that are standard on all
Heathkit color TVs. Other features include high & low AC taps to insure that the
pictare transmitted exactly Its the "681" screen, automatic degaussing, 2 -speed
transistor UHF tuner, hi -fi sound output, two VHF antenna inputs, top quality
American brand color tube with 2 -year warranty. With optional new RCA Matrix
picture tube that doubles the brightness, Model GR -681MX only $535.00.
2
Models In 295 Sq. Inch Size
GRA- 295 -4, Mediterranean Cabinet shown
Heathkit
"295" Color
NEW
Kit GR -681
With AFT
...
$49995*
i)
$124.95'
t
TV
With Optional RCA Matrix Tube ... with the same high performance features
and built-in servicing facilities as GR -681 above ... less AFT, VHF power tuning
and built -in cable -type remote control. You can add the optional GRA -295.6
Wireless Remote Control at any time. New optional RCA Matrix tube doubles
the brightness, Model GR- 295MX, $485.00.
564.95'
GRA -296 -1, Contemporary Walnut Cabinet shown
Both the GR -681 and GR -295 fit into the same Heath factory assembled
cabinets; not shown Early American style at $109.95'
NEW Deluxe Heathkit "581" Color TV With AFT
The new Heathkit GR-581 will add a new dimensiòn to your TV viewing. Brings
you color pictures so beautiful, so natural, so real ... puts professional motion
picture quality right into your living room. Has the same high performance
features and exclusive self-servicing facilities as the GR -681, except with 227
sq. inch viewing area, and without power VHF tuning or built-in cable -type
remote control. The optional GRA -227 -6 Wireless Remote Control can be
added any time you wish. And like all Heathkit Color TV's you have a choice
of different installations
mount it in a wall, your own custom cabinet, your
favorite B &W TV cabinet, or any one of the Heath factory assembled cabinet,.
GRA -227-2, Mediterranean Oak Cabinet shown
$109.95'
Kit GR -295
$44995*
(less cabinet)
2
Models In 227 Sq. Inch Size
NEW
Kit GR -581
with AFT
$41995
...
Iles:. cabinet)
Heathkit "227" Color TV
Same as the GR -58I above, but without Automatic Fine Tuning
. same
superlative performance, same remarkable color picture quality, same built -in
servicing aids. Like all Heathkit Color TV's you can add optional Wireless
Remote Control at any time (GRA- 227 -6). And the new Table Model TV
Cabinet and roll around Cart is an economical way to house your "227"
just roll it anywhere, its rich appearance will enhance any room decor.
Kit GR -227
NOW ONLY
...
GRS- 227 -5, New Cert and Cabinet combo shown
$54.95'
Both the GR -581 and GR -227 fit into the same Heath factory assembled
cabinets; not shown, Contemporary cabinet $64.95'
NEW Heathkit Deluxe "481" Color TV With AFT
The new Heathkit GR-481 has all the same high performance features and es-
clusive self- servicing aids as the new GR -581, but with a smaller tube size ...
180 sq. inches. And like all Heathkit Color TV's it's easy to assemble
no
experience needed. The famous Heathkit Color TV Manual guides you every
step of the way with simple to understand instructions, giant fold -out pictorials
.. even lets you do your own servicing for savings of over $200 throughout the
life of your set. If you want a deluxe color TV at a budget price the new Heathkit
GR -481 is for you.
...
GRA- 180-1, Contemporary Walnut Cabinet shown
Heathkit "180" Color TV
$37995*
(less cabinet
& cart)
2
Models In 180 Sq. Inch Size
NEÑ
Kit
$35995* cabinet)
Kit GR -180
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Color TV's.
GR -481
with AFT
549.95'
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Feature for feature the Heathkit "180" is your best buy in color TV viewing ...
has all the superlative performance characteristics of the GR-481, but less Automatic Fine Tuning. For extra savings, extra beauty and convenience, add the
table model cabinet and mobile cart. Get the value-packed GJt -180 today.
$42.50'
GRS-180 -5, Table Model Cabinet & Cart combo
Both the GR -481 and GR -180 fit the same Heath factory assembled cabinets; GRA -180 -2, Early American Cabinet $94.95'.
Add the Comfort And Convenience Of Full Color Wireless Remote Control
To Any Rectangular Tube Heathkit Color TV
New Or Old!
Kit GRA -681 -6, for Heathkit GR -681 Color TV's
$64.95'
Kit GRA- 295 -6, for Heathkit GR -295 & G R-25 TV's
$69.95'
-6,
Kit GRA- 227
for Heathkit GR -581; GR -481 & GR -180
$32995*
I
(less cabinet & cart)
/,.
Reception Is Simulated
On
All Sets Shown
HEATH COMPANY, OW. 178.13
NEW
Benton Harbor, Michigan 49022
FREE 1970 CATALOG!
tric guitar & amplifier, amateur
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*Mail order prices; F.O.B. factory.
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home & hobby. Mail coupon or
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a
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NOVEMBER -DECEMBER, 1969
CL-364
9
www.americanradiohistory.com
aMung you:
Astronaut Neil Armstrong
said he "thoroughly enjoyed"
replicas of members of the
Mung Dynasty sent him by a
group of Great Lakes sailors,
even though he couldn't meet
their request to put a Mung
Mungtini
on the moon.
The commander of the Apollo mooncraft sent
his regrets to the men at the Electronics Technicians School at Great Lakes Naval Training
BY JULIAN M. SIENKIEWICZ,
Lditor
Center, who claim credit for creating Omar
Mung, the modern equivalent of World War II's
Kilroy, who appears daily in The Daily News.
"Thank you for writing to me to request that
I carry a replica of your mascot, Omar Mung,
with nie to the lunar surface," Armstrong wrote
school director Lt. Cmdr. W. H. Wheeler.
"I regret that I will be unable to do so, but
requests of this nature are so numerous that I
am unable to honor any
Client. However, I
thoroughly enjoyed the
pictorial representations
of Omar's many faces
and titles," Armstrong
of
WWould you believe? Omar Mung has taken
over ELEMENTARY ELECTRONICS! Readers
who did not read pages 46 through 48 of our
September /October issue have missed the Mung
revolution. Mungs have replaced Kilroy signs
in the field of electronics. So get with it and discover the work of Mung.
We asked our readers
to send in their favorite
Mung and in return we
will award the best
Mung a shortwave receiver. Additional prizes
will be awarded to a few
runner-ups. Well, the
mail is fantastic and our
Mung Evaluation Board
Munga Lisa
is up to their ears in entries. Since the mail has
not let up, we've decided to keep the contest
open a bit longer. So don't wait. Conjure up
your favorite Mung and mail it today to Mung
Editor, ELEMENTARY MUNGTRONICS, 229 Park
Ave. South, New York, N. Y. 10003. All entries
must be postmarked on or before December 15,
1969.
A few Mungs are scattered on this page to
give you an idea of what is a Mung. These
Mungs are old-that is, they existed before the
contest started. Think up an original Mung as
did Buddy Cavitt of Medford, Ore., with his Julian
added.
Too bad, Neil Armstrong, you could have
put the first Mung on
the Moon!
The Astro Parade. Now
that the U.S. Moon Shot is in
the history books, let's take a
look at the parade of companies that advertise their
roles in the Apollo program.
If a widget made it on Eagle,
you can bet your last lunar
Munger
dollar that Widget, Inc. and
their holding company, U.S. Widget Corp. of
America, ran ads in trade and consumer papers
hoping that some of the magical lunar dust will
land on their tails. From this poor Editor's seat,
it appears that NASA should add a stipulation
to its contracts limiting or eliminating all reference to space shoots unless said company either
makes outright contributions to the space effort
(that means no
charge or at
cost only) or
pays NASA for
the privilege of
making such
Mungkiewicz (at right),
your Mung Editor. Good try,
Flying Mung
Buddy-you got one sure
vote for first prize!
No Mung on Moon! Here's
an interesting item from the
August 6th edition of the
Chicago Daily News that'll
references.
-/
Making a Mung is fun as
Buddy Cavitt of Medford,
Ore. discovered with his
Julian Mungkiewicz.
10
Af-
ter all, why
should three
brave men risk
their lives only to
have their pictures
in some company's
ad campaign?
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
4
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tticrPn;
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munications Aerospace Work
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Preflight Channel
The "unseen voice" that announces Air Shuttle arrivals, departures, and special information
at Eastern Airlines' LaGuardia termiral in New
York will now be seen on a closed circuit television system throughout the terminal. A recently installed Raytheon television system
enables ground hostesses to provide personal
contact with passengers and those waiting in
the terminal. When the hostesses are not `on
the air," the television monitors in the experiThe
few months after
...
without obligation
what ELECTRONICS
can do for you!
MAIL COUPON FOR
Raytheon closed circuit television installation at
Eastern Airlines' Air Shuttle terminal at LaGuardia
airport in New York adds a face to the "unseen
voice" reporting arrivals, departures and other
information for travelers.
mental system carry routine video messages on
flight arrivals, departures and gate numbers. The
system can be used to televise a message directly to a particular gate or area or throughout
the entire terminal.
Introducing
BIG FACT BOOK
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Name
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EVR
In the same way that a long -playing record
stores sound conveniently and inexpensively on
City
State
Zip
J
11
NOVEMBER -DECEMBER, 1969
www.americanradiohistory.com
NEWSCAN
*********************************Y
a record for later replay on standard phono-
graphs, EVR (Electronic Video Recording)
stores pictures with sound for playback through
a' standard television set. Any motion picture,
videotape or live television presentation can be
recorded for distribution on EVR.
Basically, there are three elements to an EVR
system:
1. The thin EVR film is dual- tracked, and
carries its sound in parallel lines on a magnetic
ment for slow scanning of individual sequences,
and the capability for freezing any frame on
the screen without damaging the film or dimming, flickering or blurring the image.
Since transmission to the set is direct and
there are no buildings or other interference to
contend with, there is no ghost image or other
picture or sound distortion. Nor is there any
projector noise to distract the viewer or interfere with concentration, conversation, comment
or supplementary instruction. The system can
also be operated in normal light without lowering the shades.
Although much of the EVR technology was
developed by Dr. Peter C. Goldmark, president
and director of research at CBS Laboratories,
as an offshoot of the Division's space research
programs with the U.S. Government, CBS will
not manufacture the system itself. CBS will license its production among leading manufacturers. At first, players will appear as attachment units, styled and built by manufacturers
of home entertainment equipment. Once manufacturers get into full production, customers
will be offered a variety of models with complete cartridge interchangeability. The film,
however, will be recorded, printed and inserted
in cartridges at CBS plants.
This is EVR film consisting of two side -by -side
tracks, each with a capacity of 26 minutes of
black -and -white programming and an independent
sound track. Notice that there are no sprocket holes
to wear or damage the film.
track, along with two rows of visual frames.
Although the film is miniaturized, the image reproduces with sharper definition and clarity than
a conventional television picture. The film has
no sprocket holes, thus eliminating the chances
of tearing. As further protection against damage or deterioration, a tiny cushion of air separates the layers of pictures when stored in the
cartridge.
2. The circular EVR cartridge, which holds
the film, is seven inches in diameter and has a
maximum capacity of 750 feet of film, 8.75 mm
(under 3/s inch) wide. This is equivalent to
180,000 picture frames or 52 minutes of programming.
3. The EVR player is compact, versatile and
simple to operate. A lead from the player is
easily attached by handclips to the external antenna terminals of the television set. Then the
film cartridge is placed on the player, the television set turned on to a channel that is not
broadcasting, and the player starter button
pushed. The film automatically threads itself
past an electronic sensor that converts the film
image to electrical impulses, and then transmits
these impulses -along with the sound-into the
television set. The player features buttons for
speedy forward and rewind, a fingertip adjust12
Placing the EVR film cartridge in position is as easy
as it appears. The EVR player is readily connected
to any conventional television set by a single wire.
Electronic Video Recording will give new
scope to television's immense potential in education. As the Carnegie Commission for Educational Television noted, a more versatile playback technology in educational television is the
one thing needed to return to the classroom the
ELEMENTARY ELECTRONICS
flexibility that the present uses of broadcasting
deny it. With such a technology, according to
the commission, "the teacher can select the
program, play it at the moment of his own
choosing, replay it at will in whole or in part,
interrupt it for comments." By providing this
technology, EVR can help educational television
make the "massive contribution to formal education" that the Carnegie Commission feels is
not only possible, but is imperative.
Today, teachers must schedule classwork
around broadcast hours, and they have no conwhen.
trol over what appears on the screen
With EVR, the teacher can integrate educational films more effectively into the smooth
flow of his classwork. He can preview and
choose. He can stop the program for comment
or for general discussion. He can schedule lessons at his own discretion, and show his films
either to individual students or to large groups
simply by linking a single EVR player into as
many television sets as he needs. He can even
play them in several classrooms at once.
The process of education does not end when
one leaves school. It is only just beginning. The
swift pace of change in science, technology, the
arts and industry forces millions of Americans
to study at home, and many actually enroll in
formal correspondence courses to sharpen and
extend their skills.
-or
X Out X -Rays
A high -voltage diode that prevents X-ray
radiation from color TV sets, in addition to
providing excellent voltage regulation in the
newer -generation transistorized TV circuits, is
now available for 1970 model design. The new
oow...a heller
igt4
to drive and afliust
hex sockel screws
...IN PRECISION
WORK
With the tools in this new, compact convertible screwdriver
set, you can turn all types of hex socket screws ... in all
types of locations ... faster, easier than with conventional
keys.
Handy midgets are ideal for such delicate, precision work
as assembly and servicing of instruments and controls. Remarkable
"piggyback" torque amplifier
handle adds grip, reach, and
power needed for other
applications, lets you
do more jobs
with
fewer tools.
PS -89 SET
8 midgets (hex size .028"
thru Vs") plus hollow,
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see -thru plastic case fits
pocket or tool box,
doubles as bench
stand.
O O
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REQUEST COMPLETE HAND TOOL CATALOG
-
which includes information on other Xcelite Compact Sets,
slot tip Phillips /Scruloxw screwdrivers, nutdrivers,
too
and combinations.
/
Nationwide availability through local distributor
r--
-
XCELITE, INC., 80 Bank St., Orchard Park, N. Y. 14127
Send complete tool catalog, which
all Xcelite Compact Sets.
includes information on
name
"You say you live in a lighthouse?
Here's just the setup for your
Nil
all
addresq
L
state & zip
city
In Canada contact Charles W. Pointon, Ltd.
13
NOVEMBER- DECEMBER, 1969
www.americanradiohistory.com
NEWSCAN
********.`r**.`r**
diode has particular appeal to color TV manufacturers in view of the recently imposed Federal legislation compelling adherence to a still to -be -set standard for a maximum acceptable
radiation level. A retrofit kit, now in the late
stages of design, offers a simple means of protecting present production model TV sets, as
well as approximately 25 million color sets
already in the homes of consumers.
The high -voltage diode operates as a simple
shunt regulator, conservatively rated to pass a
maximum operating current of 3.0 mA. Regulation is one kV from 0.1 to 1.2 mA. at an operating voltage of 25 kV. By its physical nature, the
diode does not produce X -rays itself. Moreover,
it exhibits a unique fail -safe characteristic that
prevents radiation from still another source: the
face of the picture tube. When conventional
voltage regulators fail, they cause a much higher- than -normal voltage to be imposed on
the face of the TV picture tube. This abnormally
high potential can result in X -rays passing
through the face of the picture tube and the
protective glass front of the set. In contrast, if
the Victoreen high voltage diode should fail, a
safe, lower- than -normal voltage is imposed on
the picture tube.
Diodes have only two connections and are
basically simple devices. This simplicity carries over into the operational characteristics and
the design of high voltage circuits in TV sets.
The high -voltage diode was developed by
Victoreen Instrument Division, Victoreen Leece
Neville, Inc., of Cleveland, Ohio.
News and views
from e /e's
listening post
by Don Jensen
A few months ago we looked at stations
operating from the vital Persian Gulf area. Response to this column suggests that DXers are
interested in other broadcasts from the volatile
Middle and Near East.
Many SWLs prefer those stations which
broadcast in English. Here are a few of the
easier ones from this global hot spot.
Station
Radio Cairo
Kol Israel
Radio Amman
Radio Beirut
BBC Relay
Syrian B.S.
Radio Ankara
Radio Kuwait
Radio Iran
Country
kHz
UAR
9,475
9,009
GMT
Jordan
Lebanon
Cyprus
Syria
Turkey
Kuwait
9,560
11,820
11,955
15,165
15,160
15,405
0200
0400
1600
0230
0300
2030
2200
1600
Iran
17,738
2200
Israel
Too easy? Try these!
Widely mentioned in the newspapers lately,
but not reported by SWLs, is a special program
aired by Iraq's Radio Baghdad. The foreign
correspondents call this one The Voice of the
Storm. It's a propaganda program prepared by
Al Assifa, the military wing of the Palestine
National Liberation Movement, Al Fatah.
New Victoreen Instrument diode will eliminate co/or
TV set X -ray radiation. Designed for set makers to
build into 1970 models and to fit many existing sets.
1911. r.l
I;Ì -i1 :I,JI
i,lìS,S
All
ä
t.:c
ET.FMENTARY ELECTRONICS
www.americanradiohistory.com
For four years, but especially since the Six
Day War of June 1967, Al Assifa's fedayeen
(guerrillas) have conducted military and sabotage raids into Israel from camps in Jordan,
Syria and Egypt. Their avowed aim is to free
Palestine (Israel) through armed struggle.
According to Fatah leader, Abu Amar, "Public relations and the circulation of information
has not been one of our strong points-we are
primarily an action organization." Amar says,
however, that Fatah hopes to better explain its
case to the world when it has the necessary
money and material.
Until then, it relies mostly on the single program over Radio Baghdad, which is broadcast
daily from 1830 to 1915 GMT in Arabic; 1915
to 1930 in Hebrew. Frequencies haven't been
announced, but you might try 6,155, 7,180 or
9,555 kHz., as conditions permit. Reports of this
program may go to Radio Baghdad, or to Al
Fatah, 18 Boulevard du Colonel Amirouche,
AlgeFs, Algeria.
We're Right! Yes, Virginia, there is a Voice of
the Coast! In an earlier column we mentioned
receiving conflicting information about a station in Sharjah, one of the Trucial States. Official British sources now confirm that the Voice
of the Coast is active on 6,040 kHz., with a 10
kilowatt shortwave transmitter.
It's located at the headquarters camp of the
Trucial Oman Scouts, a British -officered constabulary, about four miles from the only town
in this barren sheikdom. Its all- Arabic programming supposedly is aimed at domestic audiences,
but we feel that there's more than meets the eye
here. Overseas monitors have heard the Voice
of the Coast -its tongue- tangling Arabic ID is
"Sawt as -sahil min al- imarat al- mutasalihah,"
it's said-around 0230 and 1500 GMT. As far
as we know, it hasn't been logged stateside yet.
And medium wave DXers are chasing the
new BBC Eastern Relay station. Moved from
Aden's Perim Island to Masirah, another island
in the Arabian Sea off Muscat and Oman, it
uses new and ultra -powerful broadcast band
transmitters. This is tough, but we bet some east
coast sharpie will get this on 700-701 kHz. this
winter.
Tip Topper. East of New Guinea lies the
island of Bougainville. Geographically part of
the British Solomon Islands, Bougainville's administration, however, is Australian, under a
UN trust mandate. Until last year the island had
no broadcasting station of its own.
Other radio services didn't really meet the
needs of the people, so Australian authorities
decided to establish a local station, Radio Bougainville. On April 20, 1968, a two kilowatt
shortwave outlet officially opened at Kieta, the
main town.
Most programs are in pidgin English, the
strange lingua franca of the islands. Broadcasts
include newscasts, health, agricultural and edu-
N
WRITE
FOR
1970
SENT FREE
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on sale now or write Davis Publications, Inc. /229 Park Ave. S. /New
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postage and handling.
protect
copies of
your
and preserve)
Elementary
Electronics
A sensible way to
durable, custom -designed Library Case will protect your
copies Of ELEMENTARY ELECTRONICS from dust and wear. At
the same time, it will help you conserve valuable space and
reduce library clutter.
Each Library Case has a muscular 9W "x64 "x45,g" frame
that can hold 24 issues of ELEMENTARY ELECTRONICS.
In elegant washable Blue simulated leather, its spine is
embossed with 16 -k gold lettering for maximum legibility.
(Each Library Case also includes gold transfer so you can
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To: JESSE JONES BOX CORP.
P. 0. Box 5120, Dept. D, Philadelphia, Pa. 19141
ELEMENTARY ELECTRONICS
Please send me
Library Cases at $3.50 each.* I understand this price
includes postage, packing and handling. ( *3 Library
Cases for $10.00, 6 for $19.00.) My check (or money
is enclosed.
order) for
NAME
(PLEASE PRINT)
ADDRESS
CITY
STATE
2
Note: Satisfaction guaranteed or money rel.Jided.
Allow 3 weeks for delivery
V
-
J
15
NOVEMBER-DECEMBER, 1969
www.americanradiohistory.com
f1X
f:FNTRAI
cational features. Local songs, many of them
specially recorded on Bougainville by the station staff, and American country and western
music are popular. The station is administered
by an Australian radio officer, but the half
dozen or so announcers are all local people
trained at Port Moresby.
Low power and an early, early sign off made
Radio Bougainville a hard one to hear in the
U.S. But recently, DXers have been reporting
improved signals on 3,322.5 kHz. One reason
is that the station now has extended its schedule to 1200 GMT, a more favorable hour.
Radio Bougainville verifies accurate reports
with the same attractive and information -packed
QSL folder used by the other administration
broadcasting stations in Papua and New Guinea.
Bandsweep. 834 kHz. -Radio Belize, British
Honduras, has been regularly logged by a
Cicero, Ill., listener, sometimes nearly obliterating WCCO, Minneapolis, during the evening.
4,777 kHz.-Libreville, Gabon, has been in the
news recently as one of the originating points
for the supply airlift to Biafra. Libreville's SW
outlet can be heard around 0500 GMT. 4,845
kHz.- Another African, Radio Botswana has
an English language newscast at 0430 GMT.
6,045 kHz.-Panamanians have been as scarce
as hen's teeth for several years, but La Voz del
Baru is now being logged around 1030 GMT
with typical Latin American programming.
7,301 kHz.-Amazing Radio Biafra, with its
Swiss -made, 10 kw. portable transmitter, often
puts in decent signals after 0500 GMT. 9,520
kHz.-The voice of one of Peru's major newspapers, Radio La Cronica is a good bet on some
nights. All in Spanish, of course. 11,825 kHz.
-Strongest signal in years, says a Canadian listener about Tahiti's shortwave outlet. Does well
until 0800 GMT sign off. 21,740 kHz.-Seldom
venture this high on the dial? Try Radio Australia's North American beam around 0100
GMT.
(Credits: John Czupowski, Ill.; Dan Ferguson, Fla.; Leslie Marcus, N.B., Canada; A. R.
Niblack, Ind.; Gregg Calkin, N.B., Canada;
Dick Heggs, B.C., Canada; North American
Shortwave Association)
Radio Rebelde. Every SWL knows the mighty
voice of Fidelismo, Radio Havana Cuba. Cuban
propaganda programs are widely heard (if little
listened to) in North America. But in the southern half of this hemisphere their impact probably is greater. In steamy Brazilian river towns,
in Indian barrios high in the Andes, the now
commonplace transistor radios often are tuned
to Havana's powerful stations.
These broadcasts originate from transmitters
at Cayo La Rose, site of a former textile factory
near the town of Benta, 23 miles west of
Havana. When built in 1961, the whole installation -Swiss transmitters, Czech broadcasting
equipment and all-was valued at $35 million.
The investment is even greater now. But Castro's radio was not always so plush. In fact, his
first attempt at shortwave broadcasting was a
flop!
From November 1956, when Fidel and 80
followers splashed ashore near Niquero, until
late the following year, the revolt against the
Batista regime struggled along. Striking from
mountain camps, constantly on the move, the
rebels of the 26th of July Movement were in no
position to begin clandestine broadcasting. Their
radio gear consisted of some captured Cuban
army transmitters, plus 20 walkie-talkies smuggled in from the U.S. with the help of an official
in Batista's public works ministry. It was used
only for short -range field communications.
But after 14 months of fighting, Castro felt
ready to start broadcasting to the Cuban people.
According to the late "Che" Guevara, he broadcast the first program early in February 1958,
from a hidden encampment high in the Sierra
Maestra Mountains.
A radio technician lashed together a semi portable station, using a revamped amateur
band transmitter. But, said Che, the first try was
something less than a success. The audience
totaled just two-a farmer who lived a few hundred feet across the dusty road, and Castro,
himself, who had the only receiver in the rebel
camp.
A few days later, on February 23, world
headlines reported that Castro supporters in
Havana had kidnapped famed race driver Juan
Fangio to dramatize their struggle. That same
evening, a lesser known, but more important
development occurred high in the Sierra Maestra. Transmission bugs worked out, the makeshift station began regular operations.
Crackling across the 40 -meter ham band,
from Oriente to Pinar del Rio, went the call
"Aqui Radio Rebelde, transmitiendo desde la
Sierra Maestra en territorio libre de Cuba!"
A far cry from today's propaganda mill, still
that broadcast marked the real beginning of
Fidel Castro's radio voice.
-
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Max knows where every one of our cars is. Every
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Of course, we still toss in the free S &H Green
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with four IF stages for best sensitivity, selectivity, and signal -to -noise ratio. It operates on batteries or AC through a built -in power supply
and battery rejuvenation circuit. The 6252A fea-
Hey Mable! Packaged Cable!
Now you can buy your coaxial cable in handy
dandy packages, thanks to Amphenol. The line
includes pretested RF cable assemblies most
used by communications experimenters, CBers,
and hams. Pictured, for example, is a 20 -ft.
length of RG -58/U type polyfoam cable with
Astroplated PL-259 connector on one end, spade
lugs on the other. So now you don't have to
bother with the salesman measuring and cut-
Channel Master 6252A Police- Public Service
Band Receiver
tures variable squelch, and is supplied with an
external antenna connecting cable for mobile
use with standard car antennas. And there's a
write -on log panel to record most -used frequencies. Dual Band Model 6252A price is $59.95
and you can write for further information to
Channel Master, Ellenville, N.Y. 12428.
All Set for Cassette?
Those progressive folk, Ampex, have come
up with a portable cassette tape player, the Tune
Tripper, which they guarantee will give you a
Amphenol Packaged Coaxial Cable Assembly
ting short lengths of cable and searching bins
for the proper coax connector. There's also a
3 -ft. package, ideal for use as a patch cord or
communications jumper cable, between radio
transceivers and linear amplifiers, coaxial
switches, test equipment, etc. Other lengths go
from 12 to 100 ft. Prices and literature available from Amphenol Distributor Div., Bunker Ramo Corp., 2875 S. 25th Ave., Broadview,
Ill. 60153.
We the People Want Public Service
Included in Channel Master's new line of
public service band communications receivers
is Model 625A, which covers the 30 -50 MHz
low band and the 147 -174 MHz high band. It
has three separate tuner and converter circuits
Ampex Tune Tripper Portable Cassette
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ELEMENTARY ELECTRONICS
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good trip. Tune Tripper, or AST-1, is monaural, powered by six batteries, measures 6 x 21
x 10 in., and weighs 21/2 lb. with batteries. You
can feed the Tune Tripper with any of Ampex
Stereo Tapes' more than 6000 selections. The
price is $29.88 and the source is Ampex Corp.,
2201 Estes Ave., Elk Grove Village, Ill. 60007.
Join the Mod Squad
Here's a new Mosley CB cubical quad with
polarization which they're calling the Mod
Quad (Model MCQ- 27VH). The switching system includes a double radiator element, two
gamma matches, and a polarization control box
which permits polarization change at the flip
of a switch from within the base station. The
Mod Quad has three widely spaced elements on
14 -ft. boom for top gain. High directivity elim-
N5LFiyL vows,
DiRECT40015 ASS
SVGßCSTiRSFS
Edmund 6 -/n. Mirror Telescope Optics Kit
assembled. The mirror itself is already ground
and polished, aluminized and overcoated, and
there's a % -in. thick elliptical diagonal with
13/4-in. major axis and 11/4 -in. minor, a 28 mm
focal length Kellner eyepiece with 50° field of
view and standard 11/4 -in. barrel diameter and
2 achromats mounted in black anodized aluminum. The kit comes with a 36 -page book,
"Telescopes You Can Build," as well as specific
instructions. The 6 -in. reflector telescope will
pick up four times as much light as a 3 -in.
scope, enabling you to view stars up to the 13th
magnitude and resolve star clusters. To order
by mail, or for more details write Edmund
Scientific Co.. Edscorp Bldg., Barrington, N.J.
08007.
Reverrrrrb!
You can convert your sound system, stereo
or monaural, to full- dimension reverberated
sound with this new Gibbs Reverberator. Featuring a 10 -watt amplifier specifically designed
for reverberation, the unit uses solid -state components. Distortion is less than 3% at 1000 Hz,
and both input and output impedance is 8 ohms.
There are terminals on the rear panel for stereo
or monaural amplifier leads and an auxiliary
Mosley Mod Quad MCQ-27VH
inates unwanted side and back signals and low
radiation angle keeps the signal close to the
ground for maximum distance. Construction is
of copper-coated steel wire, heavy -duty aluminum tubing, molded high- impact insulators, and
stainless steel hardware. Feed point impedance
is 52 ohms nominal, and the unit has forward
gain of 9 dB compared to reference dipole, 11.1
over isotropic source. The Mod Quad withstands
a wind load of 151 lbs. and weighs about 40
lbs. Price is $122.05 and you can get more
specs from Mosley Electronics, Inc., 4610 N.
Lindbergh Blvd., Bridgeton, Mo. 63042.
By Jupiter! Via Telescope
Now that all the world is an astronomer,
wouldn't it be wonderful to have your own
backyard telescope? Can't afford it? Edmund
Scientific have put on the market a 6 -in. mirror telescope optics kit (stock No. 71,191) for
$75.00 which would cost about $250.00 already
,,,,,,,,1,,,,,11,1,,,,,,1,
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20
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
******************** * * * * * * * * * * * * * * * * * * * * * * * * * * ** * **
speaker. Controls on the front panel permit
full tone control and the amount of reverberation desired. You can also run the music source
without turning on the reverberation unit or
for paging, voice, or music distribution. The
3246T has microphone precedence-permitting
paging over a program in progress. Rear of
chassis has an AC outlet, and a low- frequency
filter may be switched in to cut feedback and
protect speakers from overload. Mike inputs
are switch -controlled for low or high impedance. There are two auxiliary inputs to connect
a phonograph, tuner or tape recorder. It can be
used in either constant-voltage or standard im-
Gibbs Reverberator
disconnecting any amplifier or speaker leads.
Price is $70.00 and further information may
be obtained by writing to Gibbs Special Products Corp., 450 N. Main St., Janesville, Wis.
53545.
Now Hear This! PA Amp!
The new Allied 45 -watt public address amplifier, model 3246T will power sound columns,
outdoor weatherproof trumpets, indoor baffled
speakers, or may be packed into a speaker case
for portable use. It features a silicon- transistor
circuit, inverse feedback, sound reproduction
Allied 3246T Public Address Amplifier
pedance installations. Other features: separate
calibrated bass and treble controls, gain controls for mike and auxiliary inputs and extra
large master gain control. Frequency response
is 40- 10,000 Hz. The 3246T amplifier is priced
at $79.95 and you can. get an optional top mounting 4 -speed turntable for $24.95. Write
Allied Radio Corp., 100 N. Western Ave.,
Chicago, Ill. 60680 for info.
(turn page)
Learn more
about electronics this easy way
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with diagrams that are easy to follow..: a source of up-to -theminute information for everyone interested in electronics who
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MAIL THE COUPON below today and you can save
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HEY, LOOK ME OVER
... * * * * * * **
Continued
Neat Li'l Amp
We have here model 790 from Trutone Electronics, an all -silicon solid-state audio amplifier
with a sine wave output of 6 watts. Can be
used at home, in offices, schools -anywhere
you want microphone paging or music. The amplifier is supplied with one input for high -impedance microphone or music; speaker output
NEW DEVELOPMENTS in the world
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Trurone Raymer 790 Amplifier
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THAT'S WHERE the bigger and better coverage you find in every issue of SCIENCE
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Swing from SWL to BCB
Mosley Electronics' TRS -57 transformerbalun for SWL antennas has been developed
to adapt their SWL-7 and RD -5 shortwave listening antennas to receive standard broadcast
bands below 4 MHz. The transformer -balun
automatically transforms the doublet into the
long wire antenna necessary for broadcast
(Continued on page 99)
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Should the output of the amplifier be shorted,
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91405.
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10.
Now available from EDI (Electronic Distributors, Inc.): a catalog
containing hundreds of electronic
items. EDI will be happy to place
you on their mailing list.
11.
Bargains galore, that's what's in
store! Poly-Paks Co. will send you
their latest 8 -page flyer chock -full of
Poly -Paks' new $1.00 electronic and
scientific "blis -dor" paks and equipment.
6.
m
ti
mom tríin'
lr
son
a..
----
MIMI mom
maim Itosmium
h
1
tcoi61
SHORTWAVE RADIO
Now, get the all -new 512 -page,
fully Illustrated Lafayette Radio 1969
catalog. Discover the latest in CB
gear, test equipment, ham gear, tools,
books, hi -fi components and gifts.
Do it now!
*5. Edmund Scientific's
new cata-
log contains over 4000 products that
embrace many interests and fields. It's
a 148 -page buyers' guide for Science
Fair fans.
4. Olson's catalog is a multi -colored
newspaper that's packed with more
bargains than a phone book has
names. Don't believe us? Get a copy.
*1. Allied's catalog
is so widely used
as a reference book that it's regarded
as a standard by people in the electronics industry. Don't you have the
1969 Allied Radio catalog? The surprising thing is that it's free!
Before you build from scratch,
check the Fair Radio Sales latest catalog for electronic gear that can be
modified to your needs. Fair way to
save cash.
7.
Get it now! John Meshna, Jr.'s
new 96 -page catalog is jam packed
with surplus buys -surplus radios,
new parts, computer parts, etc.
8.
How cheap is cheap? Well,
take a gander at Cornell Electronics'
latest catalog. It's packed with bargains like 6W4, 12AX7, 5U4, etc.,
tubes for only 33(. You've got to see
this one to believe it!
*135. Get with ICs! RCA's new
integrated Circuit Experimenter's Kit
KD2112 is the first of its kind and
should be a part of your next project.
Get all the facts direct from RCA.
Circle 135.
106. With 70 million TV and 240
million radios somebody somewhere
will need a vacuum tube replacement
140.
Ut
the
rate
of
one
a
second!
Get
niversal Tube Co.'s Troubleshooting
Chart and facts on their $1.50 flat
rate per tube.
48. fly-Gain's new CB antenna catalog is packed full of useful informa-
tion and product data that every
CBer should know. Get a copy.
111. Get the scoop on Versa- Tronlcs'
Versa-Tenna with instant magnetic
mounting. Antenna models available
for CBers, hams and mobile units
from 27 MHz to 1000 MHz.
CBers, Hams, SWLs-get your
copy of World Radio Labs' 1969 catalog. If you're a wireless nut or ex23. No electronics bargain hunter perimenter, you'll take to this catalog.
should be caught without the 1969
copy of Radio Shack's catalog. Some
equipment and kit offers are so low, 101. If it's a CB product, chances
they look like misprints. Buying is are International Crystal has it listed
in their colorful catalog. Whether kit
believing.
or wired, accessory or test gear, this
CB-oriented company can be relied
on to fill the bill.
CB-- AMATEUR RADIO
ELECTRONIC PARTS
*2.
Pep-up your CB rig's performance with Turner's M+2 mobile microphone. Get complete spec sheets
and data on other Turner mikes.
116.
No never mind what brand
your CB set is. Sentry has the crystal
you need. Same goes for ham rigs.
Seeing is believing, so get Sentry's
catalog today. Circle 102.
102.
It may be the first- Gil/er's speciality catalog catering to the SWL.
Books, rigs, what -nots- everything you
need for your listening post. Go Gil/er,
circle 146!
45.
103. Squires- Sanders would like you
to know about their CB transceivers,
the "23'er" and the new "S5S." Also,
CB accessories that add versatility to
their 5- wafters.
TOOLS
146.
*78. Xcelite's midget hex socket
screwdrivers in Xcelite's PS -89 set
let you make delicate adjustments
easier. "Piggyback" handle adds grip,
100. You can get increased CB reach, and power needed for other
range and clarity using the "Cobra - jobs.
23" transceiver with speech compresSecure coax cables, speaker
sor- receiver sensitivity is excellent. 118.
phone wires, etc., with Arrow
Catalog sheet will be mailed by B &K wires,
staple gun tackers. 3 models for wires
Division of Dynascan Corporation.
and cables from airs" to 1" dia. Get
141. Newly- designed
CB antenna fact-full Arrow literature.
catalog by Antenna Specialists has
to
facilitate the
sectionalized
been
ELECTRONIC PRODUCTS
picking of an antenna or accessory
handy
index
system.
Man, 143. Bring new life to your hobby.
from a
Antenna Specialists makes the pickin' Exciting plans for new projects-let
easy.
Electronics Hobby Shop give you the
dope. Circle 143, now.
130. Bone up on the CB with the
latest Sams books. Titles range from 44. Kit builder? Like wired prod"ABC's of CB Radio" to "99 Ways ucts? EICO's 1969 catalog takes care
to Improve your CB Radie." So Cir- of both breeds of buyers. 32 pages
cle 130 and get the facts Rom Sanis. full of hi-6, test, CB, ham, SWL, automotive and hobby kits and products
107. Want a deluxe CB base sta- -do you have a copy?
tion? Then get the specs on Tram's
all new Titan 11-it's the SSB /AM rig *42. Here's colorful 116 page catalog
you've been waiting for!
containing a wide assortment of eleckits. You'll find something for
96. Get your copy of E. F. John- tronic
interest, any budget. And Heath
son's new booklet, "Can Johnson 2- any
happily send you a copy.
Co.
will
Me
?"
Help
Aimed
for
Radio
Way
business use, the booklet is useful to
today the organ with the
Hear
144.
everyone.
"Sound -of- Tomorrow," the MeloWhippany
Electronics. It's
by
Sonic
you want to
129. Boy, oh boy
-take it anywhere. Send for
read about a flock of CB winners, get portable
literature.
and
descriptive
pics
your hands on Lafayette's new 1969
catalog. Lafayette has CB sets for all
12. C. B. Hanson new Automatic
pocketbooks.
Control records both sides of a tele46. Pick up Hallicrafters' new four - phone call automatically-turns off
page illustrated brochure describing automatically, too! Get all the details
Hallicrafters' line of monitor receivers -today!
-police, fire, ambulance, emergency,
weather, business radio, all yours at 126. Did you dig Delta's new literature package chucked full of pics and
the flip of a dial.
-if
ELEMENTARY ELECTRONICS
24
www.americanradiohistory.com
*
Starred items indicate advertisers in this issue. Consult
their ads for additional information and specifications.
LIBRARY
such
ch goodies as an FET- 114. Prepare for tomorrow by
gnition system, compu- studying at home with Technical
terized auto tach, hi- voltage analyzer, Training International. Get the facts
etc.? Man, then let Delta know you're today on how you can step up in
alive! Circle 126 now!
your present job.
1969 stereo consoles. Discover how to
pick a hi -fi console for your living
109. Seco offers a line of specialized *137. For success in communicaand standard test equipment that's tions, broadcasting and electronics get
ideal for the home experimenter and your First Class FCC license and
pro. Get specs and prices today.
Grantham School of Electronics will
show you how. Interesting booklets
9. Troubleshooting without test gear? are yours for the asking.
Get with it-let Accurate Instrument
clue you in on some great buys. Why
do without?
You just gotta get Craig's new
pocket -size, full -color folder illustrating what's new in home tape recorders- reel -to -reel, cartridge and cassette, you name it! It looks like a
who's who for the tape industry.
specs
VOM,on
HI -FI /AUDIO
room.
TAPE RECORDERS AND
TAPE
14.
123. Yours for the asking- Elpa's
new "The Tape Recording Omni book." 16 jam- packed pages on facts
and tips you should know about before you buy a tape recorder.
145. Alco Electronic Products has 28 104. You can't hear FM stereo uncircuit ideas using their remote control less your FM antenna can pull 'em in.
relay. Get 100- and -one odd jobs done Learn more and discover what's availat home without calling an electrician. able from Finco's 6 -pages "Third Di- 31. All the facts about Concord
mensional Sound."
Get all the facts today!
Electronics Corp. tape recorders are
yours for the asking in their free 1970
119. Kenwood puts it right on the catalog. Portable, battery operated to
SCHOOLS AND EDUCATIONAL
line. The all -new Kenwood FM- stereo four -track, fully transistorized stereos
*136. You can become an electrical receivers are described in a colorful cover every recording need.
engineer only if you take the first booklet complete with easy- to-readstep. Circle 136 and ICS will send and-compare spec data. Get your 34. "All the Best from Sony" is an
8 -page booklet describing Sony- Superyou their free illustrated catalog de- copy today!
scope products -tape recorders, miscribing 17 special programs. ICS
crophones, tape and accessories. Get
also has practical electrical courses 30. Shure's business is hi
-fi
cara copy today before you buy!
that'll increase your income.
tridges, tone arms, and headphone
amRs. Make it your business to know
35. If you are a serious tape audio*74. Get two free books -"How to Shure!
phile, you will be interested in the
Get a Commercial FCC License" and
all new Viking /Telex line of quality
"How to Succeed in Electronics"
17.
Mikes,
speakers, amps, re- tape recorders.
from Cleveland Institute o/ Electronceivers -you name it, Electro -Voice
ics. Begin your future today!
makes it and makes it good. Get the
TELEVISION
straight poop from E-V today.
*3. Get all the facts on Progressive
70.
Need
a
new TV set? Then asEdu -Kits Home Radio Course. Build
TV kit. Heath has
20 radios and electronic circuits; 99. Get the inside info on why semble a Heath
B
&W
and color, portable
all
sizes.
Koss
/Acoustech's
solid -state ampliparts, tools and instructions come
fiers are the rage of the experts. Col- and fixed. Why not build the next
with course.
orful brochure answers all your ques- TV you watch?
142. Radio- Television Training of tions.
127. National Schools will help you
America prepares you for a career
learn all about color TV as you
slot a job. 16 big kits help you learn 26. The all new, lavishly- illustrated, assemble their 25 -in. color TV kit.
as you build. 120 lessons. Get all the full -color brochure, "At Home With Just one of National's many exciting
facts today!
Stereo" clues you in on H.H. Scott's and rewarding courses.
-
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NOVEMBER- DECEMBER, 1969
25
www.americanradiohistory.com
5
P-04
6 PxP
IF
EN
`,T=
7 N-B3
John W Collins
11
NxN
12
13
14
15
KBxB
KNxP
B-K3
B-K2
8 PxP
9 0-0
10 B-KN5
PASSANT
By
PxP
B-N5#
P-04
BxB
R-K1
Q-K2
16 OR-B1
BxN
QxB
NxB
P-KB31
0-02
K-B21
White is ahead in development and controls
more space, but Black has the sounder pawn formation. The over -all chances are even.
Petrov Defense. This bears the name of
A. D. Petrov, a Russian of the last century. It
is an immediate counter-attack against the
King's Pawn, semi -open, initially full of traps,
and quite sound, but rather short on strategic
Al
.al
conceptions. Here is Lasker's Variation, marked
by an early exchange of Queens:
Grandmaster Samuel Reshevsky, five times
Champion of the United States, once wrote:
"It is essential for the beginner and the average
player to acquire a basic knowledge of the openings. In my opinion, it is unwise for such
players to attempt to master all the openings;
instead, they should concentrate on a few and
learn them thoroughly." This is good practical
advice for the player who does not have time or
material to study, and for the one who has difficulty in understanding and remembering. But
the ideal is to know at least a little something
about all of the debuts. An idea gleaned from
the study of one never actually employed can
frequently be incorporated into one played
every day. Limitation can be self- defeating.
Giuoco Piano. The Giuoco Piano (Quiet
Game) may be the oldest recorded opening
which dates back to 1490! Except for Mednis
and Rossolimo, American masters consider it
too drawish, Black usually being able to enforce. . . . P -Q4 and to catch up in development. But the Giuoco is many -sided and can
range from the dull to the wild. This is the
classical variation of it:
P-K4
2 N-KB3
1
P-K4
N -QB3
3 B-B4
4
Black
P -B3
-B4
N -B31
B
1
P-K4
N-KB3
P-K4
2 N-KB3
3 NxP
P-03
NxP
4 N-KB3
5
0-K2
Q-K2
6 PQ3
N-KB3
7 B-N5
QxQ#
8
BxQ
B-K2
9 N-83
10 0-0-0
11 KR-K1
P-B3
N-R3
N-B2
12 B-B1
13 B-Q2
14 P-04
15 B-03
16 P-KR3
N-K3
B-02
P-KR3
P-04
R-01
Black
White
With Queens off and a symmetrical position,
there are no real winning chances for either side.
Colle System. Edgar Colle, a Belgian master,
invented this one and scored many brilliant
victories with it. It is a slow starter, and it
shuts in the Queen Bishop, but it often erupts
dangerously. The King's Fianchetto Defense
is a very logical response:
P-04
1
P-04
2
3
N-KB3
P-K3
N-KB3
4
QN-02
QN-02
5
P-B3
P-KN3!
B-N2
6 B-03
7
P-B4
0-0
0-0
8 P-QN41
9 PxP
10 B-N2
Q-N3
12 P-0R4
11
13
14
PxNP
N-K1
N-03
N-N3
BxB
B-B41
PxB
P-N5
ON-B5
(Diagram on page 30)
g
Equal chances.
(Continued on page 30)
White
ELEMENTARY ELECTRONICS
26
www.americanradiohistory.com
10 Reasons why
RCA Home Training is
Transistor experiments
on programmed breadboard
using oscilloscope.
your best
investment
for a rewarding
career
in electronics:
1
LEADER IN ELECTRONICS
TRAINING
RCA stands for dependability, integrity
and pioneering scientific advances. For
over a half century, RCA Institutes,
Inc., has been a leader in technical
training.
2
RCA AUTOTEXT TEACHES
ELECTRONICS FASTER, EASIER
-
Beginner or refresher AUTOTEXT,
RCA Institutes' own method of Home
Training will help you learn electronics
faster, easier, almost automatically.
3
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JOBS ARE OPEN NOW
RCA Institutes can help you qualify for
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of well paid electronics jobs go unfilled
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4
WIDE CHOICE OF CAREER
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Select from a wide choice of courses
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Electronics Fundamentals to advanced
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Career Program begins with the amazing AUTOTEXT method.
5
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For those working in electronics
6
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or
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PERSONAL SUPERVISION
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All during your program of home
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RCA Institutes experts who become
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help you over any "rough spots that
may develop.
7
RCA INSTITUTES, INC. Dept. EA-N9
320 West 31st St., N.Y., N.Y. 10001
VARIETY OF KITS, YOURS TO KEEP
At no extra cost, a variety of valu-
Canadians: These same RCA courses
No
able specially engineered kits come with
your program-yours to keep and use
on the job.
are available to you in Canada.
delay. Your
postage.
inquiry will be referred to our chool
ill
in Canada.
KIT AND
TRANSISTORIZED
8 VALUABLE
OSCILLOSCOPE
TV
All courses and programs approved
for veterans under new G. I. Bill.
You will receive in most career programs a valuable oscilloscope. Those
enrolled in the TV Program or courses
receive the all -new Transistorized TV
Receiver -exclusive with RCA. (Picture
ACCREDITED MEMBER National Home Study Council
CONVENIENT
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You can take advantage of RCA's
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tube available at additional cost.)
Construction of Oscilloscope.
9
r
-
I
CLASSROOM TRAINING ALSO AVAIL
ABLE. FREE CATALOG ON REQUEST
If Reply Card Is Detached-Send This Coupon Today
r
RCA INSTITUTES, INC.
Home Study Dept. EA N9
320 West 31st Street
Construction of Multimeter.
New York, N.Y. 10001
Name
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Zip
Check here if interested in Classroom Training
29
NOVEMBER -DECEMBER, 1969
www.americanradiohistory.com
EN
;j
Colle System. Text on page 26.
IKE
i
Black
;; : V&
:
i
ir.,j/
i i
j}}
it/AVI E
%''
i%
%
j
,1
',
%
i
'///
%
%,
.
%
.
%
i
ÿ
%
White
Slav Defense. The Slav Defense is the largest
branch on the Queen's Gambit tree. A favorite
of former World Champions Euwe and Smyslov,
it is also suitable for beginners and average
players because it affords easy development,
good piece play, and a promising ending. The
Dutch Variation brings out its main features:
1
P -Q4
P -04
8 0 -0
0 -0
2 P -QB4
P -0B3
9 Q -K2
QN -02
3 N -KB3
4 N -B3
5
P -QR4
6 P -K3
7 BxP
N -B3
10
P
-K4
PxP
B -B4
11
R
-01
P -K3
B -QN5
-N5!
0-R4
B
N -04
12 P -K5
13 N -K4
P -B3
N /2xP
14 PxP
at Santa Monica, Calif., finishing ahead of
Fischer and Reshevsky. In the Interzonal
Tournament at Sousse, Tunisia, 1967, he wound
up in the top eight and thereby qualified for the
Challenger Matches. In these he successively
defeated Geller, Larsen, and Korchnoi, and thus
earned the right to play Petrosian for the title.
The final result of the championship match
was Spassky 121/2,'Petrosian 101, the decisive
draw in game No. 23 occurring on the loser's
40th birthday. Play in the match was of a high
order, though often marked by mistakes, and
the number of wins was unusual for a championship match.
Spassky resides in Moscow (the site of the
match), is married and has a two year -old son,
has a degree in journalism, earns his living by
chess, and is the editor of "64," a weekly chess
magazine.
In the following game, the 4th of the match,
Spassky (Black) essays the old, controversial,
Tarrasch Defense, obtains the more comfortable
position, "maneuvers precisely," "attacks effectively," and wins his first game.
1
P-QB4
P-K3
2
3
P-04
N-0B3
P-04
P-QB4
KPxP
N-0133
N-B3
B-K2
4 PXQP
N-B3
6 P-KN3
7 B-N2
5
8
0-0
9 B-N5
PxP
P-KR3
B-KN5
B-K3
R-K1
B-K3
12 N-N3
11
It'
i,.
E /,. //
13 R-B1
14 R-K1?
15 B-B5
16 BxB
17 P-K3
18 Q-K2
19 P-B3?
r`';
%
/ /L'
ago
33
34
35
36
37
38
39
40
OxB
KR-Q1
N-K4
B-N3
%
A big, sprawling position, not readily evaluated. Each side is well developed and has an
isolated Pawn.
B-N2
N-N3
PxN
NxN
RxR
Q-B4
R-K3
QxR
B-N3
N-R2
N-B1
R-B5
P-QR4
Q-02
K-B2
P-R5?
. . .
B-R2
R-K1
B-N8
N-N3
Q-KB3
N-65!
B-06!
0-N41
Q-R5;r
BxB
BxB
W,
,
' ft
iaiai
",/+l<
',,/,,',
Game of the Issue. Boris Vasilyevich Spassky
is the new Chess Champion of the World. Spassky was born on Jan. 30, 1937, in Leningrad,
learned the game at a very early age and was
playing tournaments when 10. At 16, he became
an International Master, at 18, World Junior
Champion, in 1966, he lost the title match to
Petrosian by 111/2-12%, but in the same year he
won the Second Piatigorsky International Cup
R-143
i>., .}
i Mir.,
;::
%'%
White
Q-02
N/3-K2
N-85
N-K3
41 K-N1
Resigns
B-B4
Position after 41
',%',%
R-N5!
N-B3
/
j.j j
B-N5
/íís.4,.Y'.%
R-B5
P-KN4
P-N3
R-0B1
32 B-B1
OR-B1
N-04
B-R3
31
0-B2
20 QR-01
21
26
27
28
29
30
0-0
10 KNxP
Black
22
23
24
25
A
ALT,
Why did White resign? Because he will be
mated, lose his Queen for a Rook or a Knight,
(Continued on page 101)
30
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
a
ELE VIENTARY
ELLECTRONICS
ETYMOLOGY
00000
By Webb Garrison
Orbit
After the chariot became the chief military
vehicle, the orbis or wheel gained new importance. A wheel- track, known to Romans as an
orbit and produced by repeatedly driving over
the same course on parade grounds and in amphitheaters such as the Circus Maximus, was
roughly circular.
Once it became apparent to astronomers that
planets revolve around the sun, the resemblance
between such a path of revolution and a wheel track was obvious. In the 5th edition of his
then -famous "New World of English Words"
(1696), Edward Phillips explained that an "orbit is properly the Tract left by a Wheel in the
Road; but Astronomers use the word to signifie
the way or course of the Sun, particularly called
the Ecliptick, and also of any other Planet moving on according to the Circle of its Latitude."
Proper or not, the word stuck in the vocabulary of astronomy. Once firmly established as
a general term for an approximately circular
pattern of revolution, the ancient term proved
just right for use by modern physicists.
Strangely, even the 1961 edition of the famous 13- volume "Oxford English Dictionary"
doesn't recognize the word in its application to
an electron spinning about the nucleus of an
atom. In spite of this scholarly snub, orbit has
become the universal label for the path in which
a spaceship- revolves. Growing
an electron
capacity to move electrons from their normal
"chariot tracks" into other orbits is basic to
many phases of atomic science.
-or
Nickel
Axel F. von Cronsted seldom rates even a
'host paragraph in an encyclopedia. To his contemporaries, the Swedish seeker after nature's
secrets seemed a harmless but uninspired plodder. They considered his life -absorbing interest
in mineralogy sure proof that he didn't know
where to focus his energy in order to make
major discoveries.
Cronsted even wasted a lot of time and energy on kupfernickel. Everyone (except Cron-
sted) knew that this common ore is worthless.
Thnnah rnnnarlike in annearance_ it yields none
of the highly- prized metal. Hence the German
name of the ore-roughly equivalent to "the
copper -colored stuff made by a mischievous
demon."
In spite of repeated failures, Cronsted continued to press his efforts to extract a metal
from kupfernickel. He finally succeeded in
1751. But the impure stuff he obtained wasn't
remotely like copper. Hard and silvery-white,
it had no known use. So it wasn't until 1754
that Cronsted got around to abbreviating the
name of the ore from which he got it and calling the new metal nickel.
Strongly ferromagnetic, the lustrous metal
eventually entered wide use as a plating material. Once an abundant supply became available, new research showed that it could be useful in production of magnetic alloys.
Today the substance that folk -lore linked
with pranks of a demon helps electronic equipment to perform technological wonders.
Static
A Until complex equipment was produced to
make the job easy, it required considerable skill
to weigh things accurately. Latin staticus indicated a state in which the needle of a balance
ceased to waver. From this usage, static entered 17th-century English to name any state or
act linked with the process of weighing.
Influenced by the fact that many disciplines
have names that end in -ics (mechanics, for
example) an "s" was tacked on the word that
designated the science of weights. Statics in time
came to be concerned largely with action of
forces producing equilibrium. In this sense, it
was the opposite of "dynamics."
With the advent of the wireless telegraph it
was found that relative equilibrium in the atmosphere fosters transmission of messages. But
pioners in the study of "atmospheric stability"
found the title -too long and clumsy, so dropped
it in favor of the familiar "statics."
As knowledge accumulated, it became clear
that even when conditions seem to be stable,
components in a field of statics are likely to produce interference. Dropping the terminal "s"
that had been added 250 years earlier, wireless
operators adopted static as a label for noise
produced by atmospheric forces outside a manmade system. It wasn't until 1918, however,
that "Webster's New International Dictionary"
included in the addenda a reference to the
special kind of interference that affects electrical communications systems.
As a result of linguistic turns and twists, a
self-contradictory label is now in universal use.
Every amateur knows that static stems from
operation of dynamic forces, rather than from
those in a system as motionless as a balance
whose needle has stopped quivering.
31
NOVEMBER-DECEMBER, 1969
www.americanradiohistory.com
Guided
ours
by Jack Schmidt
iLJ/C_J/LJ/L,_,
.Q
"... even in this age of automation our
"... a market area penetration of
70.067 % with 38.065°A response on a
engineers monitor all technical
functions ..."
selected analysis
"This whole room is full of hot tubes, so
we'll just look in the door briefly on our
way to the Makeup Department!"
.,.
CO,'
.cvs
..."
"...and in here we develop our own film!"
77
ec,
"Would you move on, Sir ... others
"... the tower weighs 247 tons, is
in the
group would like to see themselves on TV"
feet high, the top sways
in
1
132
2 I/s inches
a60 mph wind..."
32
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
elementaryNOVOEG
1888
Electronics
XTAL CALIBRATOR
You can be sure of the frequency
when calibrating your receiver
or locating new sub -band edges
when transmitting. This compact,
battery powered calibrator uses
state -of- the -art ICs and crystal
standard for accuracy, stability,
and marker signals not found in
commercially built units.
by Ed Morris, W2VLU
Just as light beacons point out
hazards to ships passing in the
night, so our Mark III Xtal Calibrator provides frequency guidance to the
SWL, the experimenter, and the ham operator.
The Merk III is a low -cost integrated circuit (IC),
crystal -controlled, highly accurate and extremely stable frequency calibrator. It provides easily identified marker pulses at 25, 50,
100 kHz, and, in fact, all the way to 200 MHz and beyond.
It helps the SWL pinpoint the frequency of the signal he is tuned to and
also makes it easier to spot and identify rare DX stations. Ham operators
will appreciate the benefits of the 25- and 50 -kHz markers in identifying
the new sub-brand edges, which are not exact multiples of 100 kHz.
A feature not found in any of the commercial calibrators currently avail-
NOVEMBER -DECEMBER, 1969
www.americanradiohistory.com
Ton can cnt Ms figure almost in half if yon
MARK III CALIBRATOR
able is the unique type of identification
produced by the Mark III. The output marker signals can be pulsed on and ofi twice a
second. This is a great aid in separating the
markers when the hand is full of QRM and
unmodulated carriers.
Ease of construction and wiring as well as
low component cost are achieved by using
two plastic ICs that can be bought for $3.35
the pair. These two ICs replace a total of 34
transistors and 48 resistors.
Entire cost to build this calibrator, using
all new parts, should be less than $23.00.
happen to own or can borrow a crystal of
the type used in our unit.
Construction time to build the calibrator
is between 3 to 5 hours, depending on the
adeptness of the constructor. Our unit is
housed in a 6 x 41/2 x 11/2-in. aluminum cabinet attractively covered with vinyl plastic
sheet which can be selected to blend with
the decor of the room the calibrator will be
used in. Even though this won't affect its
operating characteristics it will improve family relations where the living room is also
your base of operations.
It's The ICs. Mark III works in a straight.
forward manner. Circuit ICI is a hex inverter. The inverters on this IC chip generate,
S2e
C6
Ia
13
12
Ii0
u
9
It
et
i
IC2
2
4.5V
TxTAL
50kHz,
100kHz
25kHz
ICI
and IC2 contain a total of 34 transistors and
48 resistors yet each requires but .5/16 x 3/4 -in.
of space. External parts set circuit characteristics.
PARTS LIST FOR MARK Ill CALIBRATOR
battery consisting of 3 AA mer53- Miniature lever switch, 3 position, 2 ch.
cury cells (Lafayette 3274685 or equiv.)
cuit, non- shorting, positive action (Lafayette
C1
-45 pF ceramic trimmer capacitor (La3074151 or equiv.)
fayette 3272511 or equiv.)
Xtal
100 -kHz parallel resonant crystal
C2- 100-pF, 1000 -VDC disc ceramic capacitor
type S6P13 (available from Sentry Mfg. Co.,
(Lafayette 3372284 or equiv.)
Crystal Park, Chickasha, Okla. 73018 at
C3- 5000 -pF, 1000 -VDC disc ceramic capa$9.00, shipped prepaid air mail within
citor (Lafayette 3372331 or equiv.)
continental United States within 24 hours
C4, C5- 50 -uF, 12 -VDC miniature electrolytic
after receipt of order)
capacitor (Lafayette 9976085 or equiv.)
Aluminum chassis, 6 x 4 x 11/2 -in. (LaC6, C7- 0.01 -uF, 75 -VDC disc ceramic cafayette 1278190 or equiv.)
pacitor (Lafayette 3376905 or equiv.)
Bottom plate for above chassis (Lafayette
Integrated circuit Hex Inverter (Motorola
1278287 or equiv.)
MC -789P)
Crystal socket Sentry type D40 -152 (availIC2 -Integrated circuit
Dual JK Flip -Flop
able from Sentry at 15 each -see address
(Motorola MC -790P)
above)
J1 -BNC output connector, single hole mount1 -21/4 x 31/4 -in. piece epoxy glass sheet
ing, type UG652 Bill (Lafayette 32T2121
or equiv.)
Mise -Vinyl covering (Contact or equiv.),
Si, S2 -Dpdt toggle switch (Lafayette 99Tminiature eyelets, wire, solder, nuts, bolts,
6162 or equiv.) Note: only one pole used
etc.
B1
-4.5 -V
-7
ICI-
1-
111-
H
ELEMENTARY ELECTRONICS
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Bottom view during initial
assembly showing location for
electronics card sub -assembly and
battery holder, also controls
on front panel. Keep circuit
card away from chassis.
S3
S2
shape, and amplify a 100 kHz square wave and provide the marker pulses. Circuit IC2 is a dual J -K flipflop, dividing the 100 -kHz
signal to 50 kHz, and that,
in turn, to 25 kHz.
To be more explicit, IC1
contains six individual circuits, each of which is equivalent to a transistor amplifier
that provides the simple inversion function. Two of
these inverters are biased for
110
class -A operation by RI and
R2. Capacitor C3 controls
the output of the first one to the input of the
second. Positive feedback is obtained by
connecting the output of the second inverter
to the input of the first through the crystal
and trimmer capacitor Cl. The output is a
100 -kHz square wave. Because a parallel
resonant crystal is sensitive to variations
in load capacitance, the crystal can be
trimmed to exactly 100 kHz by the trimmer
capacitor.
A third inverter shapes the 100 -kHz
square wave and acts as a buffer to prevent
variations in load from reflecting back into
the oscillator, which would affect the oscillator frequency.
This buffered signal is fed to the first J -K
flip -flop in 1C2, which is connected as a
divide -by -two counter, thus dividing the output to a 50 -kHz square wave. This 50 -kHz
r
J1
SI
BATTERY HOLDER
FOR BI
J
square wave, in turn, is divided in two by
the second flip -flop in IC2 to produce the
25 -kHz square wave markers. Switch S3
selects either the 100 kHz, the 50 kHz, or
the 25 kHz output and couples the selected
signal to jack J1 through capacitor C7. This
capacitor also serves to block the DC component of the output signal.
The identification pulse function is
achieved by connecting two of the remaining inverters in ICI to form an astable multi vibrator. The time constants of resistors R3
and R4 in conjunction with capacitors C4
and C5 establish the frequency of the multi vibrators at 2 Hz. This very low frequency
square wave is coupled to the input of the
sixth inverter in ICI, which serves as a
buffer. Switch S1 is used to couple the 2-Hz
square wave pulse to the output of the
100 -kHz generator, keying
the output on and oft. Since
R3
R2
the 25- and 50 -kHz outputs
are derived by dividing the
R4
100 -kHz output, they too are
keyed at the 2 -Hz rate whenever SI is closed.
IC 2
Let's Make One. We used
a 6 x 41/2 x 11/2-in. aluminum
chassis and matching bottom
ICI
plate to house our Mark III.
You may prefer a different
x.-25 kHz
OUT
GND
+4.2
bioasswez-Demma,
TO SI
100 kHz OUT
SCREWS(4) MOUNT
ELECTRONICS
CARD
50kHz
OUT
Electronics circuit card made from
epoxy glass sheet holds all components except controls and battery. Note location of notch on
ICs before soldering into place.
á
1988
www.americanradiohistory.com
You'll need about one square foot of the
vinyl material. When covering the chassis
place the material on a smooth flat surface
with the adhesive facing up. Center the
chassis on the material and, after removing
housing, or may want to combine it into an
the protective cover from the adhesive, press
existing piece of test equipment, or build it the housing down firmly. Turn the housing
into your receiver.
over on its base and smooth out air pockets.
Scribe all the holes to be drilled in the Then fold the remaining material down over
housing and center punch them so that drill- the sides, making slits at the corners for a
ing will be accurate. A T- square will help neat, smooth finish all around. Some of the
in the layout work, particularly in laying excess material may be folded over the edges
out the slot for lever switch S3. After scrib- and pressed down on the bottom. Use a razor
ing the slot outline, drill a series of 3/32 -in. blade or X-acto knife to remove vinyl from
holes within the outline as close together as the holes and cutout in the housing.
possible. File the separations between holes
To give the unit a professional look use
with a needle file and dress the opening to dry transfer letters or decals to designate the
the scribed outline. De -burr all of the holes function of the controls and output jack.
and wash off the outer surfaces to ensure that Spray the finished lettered housing with
all dirt and oil have been removed. Unless several very light coats of clear acrylic to
this is done the pressure- sensitive adhesive protect the lettering from abrasion.
backing of the vinyl sheeting used to finish
Electronics Assembly. Except for the
the housing may not stick tightly.
controls and the batteries, all of the components are mounted on a 2'
x 31/4 x 1A6-in. piece of epoxy
POWER
(DENT.
OUTPUT
MARK ER FREQ.
glass sheet. The layout isn't
100
25
50
critical, though you may
want to follow ours as shown
in our photo. Be sure to keep
all leads as short and direct
OFF
KILOHERTZ
OFF
as possible.
All holes for mounting and
Front panel view of the Mark Ill details in -line arrangement for
wiring
components, except
all controls. Use transfer or Datak letters for control identification
those for the two ICs, the
to give your unit the professional appearance.
trimmer capacitor, and the
clip to hold the crystal, are
eyeleted to anchor comELECTRONICS CARD
ponents and wiring. A %2 -in.
drill was used for the holes
through which the pin connections from the ICs are
passed. The pins are then
folded back against the opposite side of the board. Pin
numbers are read from the
top of the IC. Starting from
the identifying notch, with
the notch to your left, and
reading counterclockwise, pin
1
is the first pin of the botN.S2
tom
row.
IDENT
SI
Hooking It Up. We used
ON-OFF
#26 bare copper wire for all
S3
interconnections and formed
OUTPUT SELECT
Jl /OUTPUT JACK
it before soldering. This permits using a low-wattage soldering iron, keeping heat
Bottom view of completed calibrator showing electronics card and
(Continued on page 102)
batteries installed. Now use Mork Ill for numerous frequency checks
GM
MARK III CALIBRATOR
'\
36
ET,s MENTARY ELECTRONICS
www.americanradiohistory.com
HOW TO
¡CONVERT
YOUR
R011
D
I
WR
Tray develop your color prints in just 7 minutes
by James A. Gupton, Jr.
that has obsolesced
appealing by the
more
made
objects
are
All
blackand
-white.
everyday
proper application of color, and this is particularly true for photographs.
Isn't it time you let electronics help you put a little color in your darkroom?
The basic reasons that cause many photographers to hesitate about
making color prints are:
1. He feels that his equipment is not suitable for color work.
2. The cost of controls to maintain required limits in processing temperatures exceeds his equipment budget.
3. Color processing takes too much time compared to black- and -white.
These once were valid reasons. But now, the availability of Eastman
Kodak's CP -5 Processing Kit makes processing color prints about as easy
as turning out black- and -whites. Developed primarily for Kodak's Rapid
Color Processors, the five -solution CP -5 processing kit can produce excellent color prints in your darkroom in just 7 minutes. Fig. 1 compares
the process time and temperatures for black -and -white prints with CP -5
processed color prints. All calculations are based on Eastman Kodak's
recommendations. Would you have believed that it takes more than double
the time to make one black- and -white print than to make one color print?
The actual process and washing time for black- and -white prints requires four times that of color prints. Of course, these times are based on
making a single print. In normal printing, we fudge a little by processing
a number of prints at the same time, thus making the time seem even less.
Critical Temperature Control. The temperature range of chemicals for
processing black- and -white prints should be 68 °, ± 3 °. Kodak recommends 65 to 75 °F. Why, therefore, is it considered so critical to maintain
the
2° required for color prints? The secret is to compensate for heat
The attraction of color is an amazing phenomenon
NOVEMBER-DECEMBER, 1969
www.americanradiohistory.com
1
@i®
CONVERT TO COLOR
loss with heat gain. To explain this further,
how would chemicals heated to 100° lose
their heat? The answer is by radiation and
conduction to cooler room air.
If we can provide a constant source of
100° heat that is in contact with the chemicals during the time of processing, the
chemicals that are giving up heat to the cooler air would, at the same time, receive heat
from the 100° source. They would thus
maintain the critical temperature constant.
Converting the Darkroom. Would you
like to know how we provided a constant
heat source in the darkroom to process color
prints? Perhaps you will want to do the
same. The first item required is a controlled
source of 100° heat to pre -heat the CP -5
chemicals. We purchased a single -element
hotplate from a local discount house for less
BLACK & WHITE PROCESS
PROCESS STEP
REMARKS
TEMP. F
TIME
TOTAL
TIME
PRINT EXPOSURE 10 SECONDS
than a buck. To control its temperature we
installed a Johnson Model T-7912 Remote
Bulb thermostat between the hot plate's
heating element and the power line. Figs. 2
and 4 illustraté correct placement of the remote bulb on top of the hotplate.
The trick in maintaining critical temperature control of the chemicals is the use of a
stainless -steel developing tray to hold the
chemicals while they are on the temperature
controlled hotplate. The steel tray will conduct the heat from the heating element of
the hotplate to the chemicals.
To calibrate the temperature on the hotplate, we first filled the stainless -steel tray
with water, since water gains heat very slowly and by the same token it loses heat at the
same rate. The heating coils in free air gain
heat rapidly and cool rapidly, but the ceramic base in which the heating coils are
mounted retain heat for some time. One
might expect this condition to cause the temperature to overshoot the thermostat's control limits. However, the location of the
CP -5 COLOR PROCESS
TOTAL
PROCESS STEP
REMARKS
TEMP. F
TIME
TIME
PRINT EXPOSURE 10 SECONDS
1. Developer
68°
1.5
1.5
1. Developer
2. Stop Bath
68°
0.2
1.7
2. Wash
3. Fixer
68°
7.5
9.2
3. Stop -Fixer
100 ±0.5°
2.5
2.5
running
100 ±2°
water
.5
3.0
100 ±2°
.5
3.5
100 ±2°
.5
4.0
100 ±2°
1.0
5.0
100 ±2°
.5
5.5
100 ±2°
.5
6.0
100 ±2°
.5
6.5
100 ±2°
.5
7.0
15.0
22.0
THE REMAINING STEPS CAN BE DONE IN NORMAL ROOM LIGHT
4. Wash
running
water
5. Hypo -Elim.
6. Wash
running
water
7. Print Flat.
8. Dry
Ferrotype
68°
2.0
11.2
4. Wash
68°
2.0
13.2
5. Bleach
68°
10.0
23.2
6. Wash
68°
5.0
28.2
7. Formalin
15:0
43.2
8. Wash
Chart details steps in processing both black -andwhite and color prints. Total time shown is for
handling single print; normally, several prints are
done at same time, thus reducing per print average.
running
water
running
water
water
9. Stabilizer
g
10. Air Dry or Ferrotype 180° Max.
FIGURE 1. BLACK & WHITE PROCESS VS CP -5 COLOR PROCESS COMPARISON.
38
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
remgte bulb and thermal gradients in the
water combine to permit very accurate temperature control. Once calibrated, you can
rely on the CP-5 chemicals being held at
exactly 100° F.
The Thermostats. Before proceeding to
the next step, perhaps you should have a
little more information on remote bulb thermostats. There are two models available:
the Johnson T -7912 and the Penn 7T11 remote bulb thermostats. The basic difference
between them is their range of temperature
control and their accuracy. The Johnson
unit's control ranges from 100 -220 °, -±2.5°,
whereas the Penn unit's range is 80-180 °,
± 1.5 °. It would appear that the Penn thermostat is the better one to use for maintaining temperature required for color processing. We selected the Johnson thermostat
mainly because we wanted the higher temperature range for use on the print dryer.
The ±2.5° accuracy will do nicely for color
processing.
In addition to maintaining relatively constant temperature of the processing chemicals, the print dryer temperature must also
be controlled. Therefore, the next step is to
mount a thermostat on a print dryer. The
thermostat is wired identically as for the hotplate. The remote bulb is positioned vertically inside the dryer between the two heating coils. Reason for placing the remote
bulb in this position is to allow the radiant
heat from both heating coils to offset the
concentration of heat by the heating element's proximity to the dryer's surface. Fig.
3 details the Johnson thermostat mounted on
the print dryer.
Fig. 3. Johnson thermostat mounted on print dryer.
Remote bulb placed inside dryer offsets radiation
from heater elements nearer dryer surface.
To calibrate the thermostat, place a stainless -steel developing tray containing water
on the surface of the dryer. This done, bring
the temperature up slowly until a water temperature of 100 °F is obtained. It should take
about one hour to stabilize the thermostat
and calibrate the exact temperature.
Now that we've completed making and
modifying our heat sources, it's time to give
a little thought to the remaining details in
the process of making color prints.
Before any processing is started, we suggest you purchase the Color Data book E-66,
titled "Printing Color Negatives," published
by Eastman Kodak, or the Kodak Color
Dataguide No. R-19. These provide the detailed information on how to process color
prints, how to correct your filter pack, and
Fig. 2. Thermostat bulb placement
is important to ensure proper
heat control in order to maintain
constant 100° source of heat.
Chemicals held in contact with
heat source give up heat to
cooler air at same time they
receive heat from hot plate.
Quantify of each of
chemicals needed to process
prints to be made during a given
printing period are kept in glass
beakers placed in stainless
steel tray on hot plate.
THERMOSTAT
BULB
ii--_,_THERMOSTAT
THERMOSTAT
CONTROL
39
NovEMBER- DECEMBER, 1969
www.americanradiohistory.com
GM
paint to kill light reflections from the enlarger.
Now let's see what remains to be done
before we can print color. Naturally we
must have suitable containers to mix our
stock solutions from the chemicals in the
CP-5 kit. We used one gallon amber glass
jugs for two reasons: 1) glass will not be
affected by the color chemicals as could occur with plastic containers, 2) amber glass
prevents light from affecting the chemicals.
(Remember how Dektol darkens if left in
clear glass containers ?)
We numbered the stock solution jars 1 to
5 corresponding to their order of usage. We
also numbered the 100- milliliter glass beakers in the same way. We used glass for the
process chemicals because glass is a fair
conductor of heat and will transfer the controlled 100° heat from the hotplate heated
water to the chemicals in a reasonable period
of time.
While on the subject of the CP -5 chemicals, it's advisable to caution you in their
use. Pay attention to Kodak's WARNINGS
CONVERT TO COLOR
how to troubleshoot print defects. The Data guide even provides you with a test color
negative which is indispensable for color filter pack correction.
Test Strips. Fortified with Kodak's
technical information on color, let's turn our
attention to test strips. Kodak recommends
keeping the exposure time constant and varying the light exposure by selecting different
enlarger lens aperture settings. Reason for
this is to eliminate potential problems due
to the reciprocity characteristics of the color
paper. In Fig. 5 you will note how the test strip exposures were made. We made four
masks for a Premier 4-in -1 easel so we could
place them in or out of the easel to make
each test exposure. If you would like to
copy these test exposure masks, Fig. 6 gives
the dimensions and materials to be used. Be
sure to paint both surfaces with flat black
REMOTE BULB
HEATING ELEMENT
110 VOLT POWER CORO
MOUNTING SCREWS
DRYER
THERMOSTAT
CUT POWER CORD TO INSTALL
THERMOSTAT
HEATING
ELEMENT.
THERMOSTAT CONTACTS
110 VOLT POWER CORD
REMOTE BULB
HOT PLATE
[]
!WIRING SCHEMATIC
HEATING ELEMENT
110
VOLT
Fig. 4. Location of thermostat
bulbs both in print dryer and
on hot plate. Electrical wiring
is same for both units. We
used Johnson T7912 thermostat
having control range from
100 to 220 °, ±2.5 °, for print
dryer because its higher
temperature range is more
suitable for dryer. We used
Penn model 7T11, whose range
is 80 to 180 °, ±1.5 °, on
hot plate. Its range falls in
range required and it has
closer temperature limit which
is better for hot plate control.
Be sure all connections are
tight and all splices are
insulated to prevent possible
contact of bare wire with hot
plate or dryer housings to avoid
chance of accidental shock.
POWER CORD
,
i
MOUNTING SCREWS
='_
40
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
i-
-_
f
Fig. 5. Left, how masks are
placed in easel for test
exposures. It is suggested you
follow same clockwise rotation
of exposure at f stops indicated
3.70't
f6.3
5.6
1
-
1
SEC.
10 SEC,
f8
f11
10 SEC.
10 SEC.
in drawing.
_
---
4 B°
-
-
PREMIER 4 -1N -1 EASEL
Fig. 6. Right, dimensions for
making masks. You should be
able to determine best f stop at
fixed exposure within four tests
from any negative to make
good print.
Material:
aluminum;
fiberglass;
or
cardboard
printed on the packages and in the instruction sheets. These chemicals are very dangerous if handled improperly, but no more
so than any chemicals used in photographic
work. So be safe-not sorry -and take
proper precautions when using CP -5. Here
are a few suggestions for safe use of any
dangerous chemicals:
1. Wear rubber gloves at all times.
2. Wear a protective apron to protect
clothing.
3. Store glass containers in rubber or plastic jackets.
4. Provide adequate ventilation at
all
times.
5. In case of an accident, immediately
flush exposed areas with fresh running
water and have someone call a physician at once.
One more thing about darkroom safety,
never touch a water faucet while holding any
electrical appliance! Your enlarger, safe light, dryer, even your electric timer can
cause a shock if normal precautions are not
observed. Again, be safe! Never take chances
PAINT "FLAT BLACK"
R.FINGER GRIP
with chemicals or electrical appliances.
The following is a list of materials you will
need to add to your darkroom to process color prints:
1. Series 10 dark amber safelight filter
2. Color printing filter set
3. Kodak color print processing kit CP -5
4. Kodak Ektacolor professional paper
Into the Darkroom. As soon as stock
solutions are mixed with the CP -5 chemicals, you're ready to set up the darkroom
equipment and get down to making color
prints. A good arrangement for the darkroom, offering maximum convenience, is illustrated in Fig. 7. Note that with the safe light a minimum of 4 feet from both the
enlarger and developing areas, you'll be able
to work with the illumination from the safe light and not have to be in total darkness.
The safety factor of a 4- minute exposure to
the No. 10 safelight of the Ektacolor paper
will provide you time to process the print
through the Stop- Fixer. The remaining steps
can be completed in normal room light.
First step in making the test exposure
strip is to build the basic color filter pack.
The first filter, which always remains in the
pack, is the UV (ultraviolet) filter. To this
filter we add a number of filters to build a
value of 50 RED. A typical combination
would be 40 RED + 10 YELLOW + 10 MAGENTA (10 YELLOW + 10 MAGENTA = 10
RED).
Close -up view details connections fo thermostat
terminals. One side of heating element is connected
directly to one side of power line cord; other
side must be connected through thermostat to
other side of 117 -VAC line.
Insert a sheet of Ektacolor paper in the
easel and cover it with the four masks. Set
the timer for a 10- second exposure, using the
light of the No. 10 safelight. Make separate
exposures at lens aperture settings of 5.6,
6.3, 8, and 11. Remove the mask with identification matching the lens setting for each
exposure and return it to its original loca41
NOVEMBER -DECEMBER, 1969
www.americanradiohistory.com
E111111111111 ,,,,,,,
®Ag
=
CONVERT TO COLOR
1111
,,,,111111 ,,,,
,
,,,,,,,1,111,,1,111,11111,,,,,,111,11,,,,,,.,.,,,,,,1,,,,,,11111111,11,11111,,,,w11.wu,
BILL OF MATERIALS
1 -Set
Color Printing Filters as follows:
40 red, 1
yellow, 1
yellow, 1
-20
1
KITCHEN SINK
5- 100 -milliliter
dJCOLD
O
1
-5
glass beakers or 3 -oz. glass
drinking glasses
-gal. amber glass
-1
tainers
1-Single- element
5
2
STOCK SOLUTIONS
TIMER
1-
-10
-5
-20 magenta, 1-
yellow, -UV filter,
10 magenta,
magenta (Note: this is
the minimum set of color printing filters;
you may want to add to the minimum for
better color correction.)
1
HDTO
,
2- Johnson
or
stock
solution
con-
hotplate
Penn remote bulb
thermostat
(see text)
4 FEET
4 FEET
E
O
1-Kodak
CP -5
color processing kit
(1 -qt.
size)
1-Package Kodak Ektacolor professional paDRYER
ENLARGER
SAFELITE
Fig. 7. This typical darkroom layout provides maximum convenience in working conditions. Safelight is
positioned for safety factor of Ektacolor paper.
tion immediately at the end of the 10- second
exposure period.
With the initial test exposure made, you're
now ready to process your first color print.
Place the print, face up, in the stainless -steel
tray (plastic trays will not conduct heat satisfactorily). Now pre -wet the print with 3
oz. of water heated to 100 °F. This brings
the tray and print up to the proper temperature. Set the timer for 7 minutes and throw
away the water used to pre -wet the print
and place the tray on the heated dryer. (Of
course you have preheated the chemicals by
placing on the hotplate a stainless steel tray
containing water and the beakers containing
the chemicals).
Take No. 1 beaker containing the heated
Solutions used during processing kept in 100 mm
beakers placed on hot plate to maintain proper
temperature. Beakers marked same as brown bottles.
per
1-Series 10 safelight
2- Stainless steel developing
trays, 8 x 10 in.
When packaged in kit form chemicals are
supplied in quart size only. However, the
five chemicals are also available in individual -gal, size packages.
1
Stock solutions are stored in brown bottles marked
to identify the order of their usage. Dark bottles
protect chemicals from damage caused by light.
developer and pour 3 oz. on the center of
the print. Now rock this tray on the dryer
to allow the developer to flow continuously
across the print. In addition to constantly
flowing fresh developer over the print, the
rocking of the tray continually transfers heat
from the dryer into the developer.
Remember -each step will require 5 seconds for draining in addition to specified
process time, so make allowances for draining time in each step. This is a very fast
process, and of the nine process steps all but
two take just 30 seconds each. Only the
developer and bleach steps require more than
30 seconds.
After completing the first color print
you'll be anxious to see the results of your
work. Take a close look at the wet print.
(Continued on page 102)
42
ELEMENTARY EI.ECTRONIC$
www.americanradiohistory.com
s
BEMENTaRY
E.G0ÌP&NiCS
by Carl Kohler
The following exercise is a pseudological
series of theoretical life situations which
might face any electronics enthusiast. The
purpose of this simplified test is to help you
determine, for yourself, approximately how
much self-control you might possess under
various pressures. Unless you take yourself
too seriously, you're in no danger of being
warped by this exercise. At the conclusion
of each of the life situations check one response or write -in your own response to
each situation. You'll find a rather wild
scoring system. Should the results please
you. share them with your family and
friends. But should the final score enrage
you, direct all poison pen letters to me c/o
ELEMENTARY ELECTRONICS and stay off the
Editor's back: by including this feature he
was only proving that he's courageous
enough to try almost anything at least once.
Good Luck and don't hesitate to cheat!
*
*
*
D.
*
*
*
interest in solid -state
a well deserved reputation for having become a minor expert upon the
subject. When you are invited to speak upon your
favorite subject before a large audience of fellow
enthusiasts, you no sooner get to the rostrum than
your mind goes totally blank.
3. Your sincere and dedicated
theory has gradually given you
Would you:
A. Laughingly explain your predicament to the audience?
B. Smoothly switch to a faked -out talk on Ovonics?
C. Tremble, perspire and break into tears?
D. Sprint for the nearest exit?
E.
* * *
constructed and installed a most
original burglar alarm system. you find that because
it keeps shorting out for a variety of technical reasons you aren't getting any sleep.
4. Having designed,
Would you:
A. Replace it with
B.
elec1. For years you have assiduously collected
tronic components that are either no longer on the
market or very difficult to find, carefully stashing
them in a large crate In your garage. One day you
discover that your wife-thinking the crate contained
discarded clothing -gave it to the Salvation Army.
Get fresh with the help at Shop -B?
E.
C.
D.
a more conventional system?
Stubbornly modify it from sound -signal to light signal?
Replace it with a large surly dog?
Refuse to do anything except buy ear -muffs?
E.
*
*
*
Carelessly forgetting to lock the door to your
workroom, you return home from work to discover
that neighborhood children have made a shambles
of all your equipment, supplies and your latest elecscratchbuilt low -power rig with
tronic project
which you planned to operate the 40 -meter band in
your off- hours.
5.
Would you:
A. Calmly begin another collection?
B. Regard the experience as a religious contribution?
C. Become hysterical?
D. Join the Salvation Army, hoping to track down
the crate?
E.
--
*
*
*
--
Would you:
Sternly remind yourself to lock the door after
this?
B. Calmly build another, stronger rig to work skip
with?
C. Rage and fume silently until you had an ulcer of
your very own?
D. Palm off the kids to the Gypsies at wholesale
rates?
A.
There are two electronics supply shops in your
locality. Shop -A is spacious, clean and offers mild
savings with discounts on almost every item. Shop -B
is a hole -in- the -wall but the sales -clerks are young
and shapely females wearing ultra- miniskirts and
provocative expressions who bend over a lot.
?
Would you:
A. Buy all your supplies at Shop -A?
B. Do all your window- shopping at Shop -B?
C. Berate the manager of Shop -A for hiring
clerks?
-a
E.
male
* * *
6. You meet a gorgeous
in love with her when
doll and have fallen madly
(Continued on page 101)
43
NOVEMBER- DECEMBER. 1969
www.americanradiohistory.com
HOW TO
BE A PA.
PATSY...
Public- address systems never seem to work
quite as intended, and electronics buffs are frequently
expected to perform major miracles with them.
The following tips should help the miracle- worker.
Ten minutes to starting time. The Royal
Grand Potentate has come all the way
from Crows Canyon for the annual lodge
banquet, and you know what a reputation
he has for laying 'em in the aisles. The MC
makes a perfunctory check of the public
address system with the one-two -three testing routine. Nothing happens!
Normally stable as the Rock of Gibraltar,
the MC is suddenly reduced to panting panic
as he hammers the mike and hollers for the
manager. And then his eye lights up with
the hope of desperation as he spots you, the
lodge electronics hobbyist, at a forward
table. Suddenly it's your tub of transistors.
Enter Thinking. You make sure the
mike's own switch is on, and you work it
back and forth to clear the contacts. You
gently tap the microphone after tightening
the cable connector on the mike head, and
you finally determine the system is truly a
corpse. The connector at the other end of
the cable is firmly snapped into the audio
wall socket. A harried scan of the room
discloses the amplifier on a shelf at the rear.
The red pilot light shows the AC Is OK.
The mike volume control and master gain
pots are set near mid -range so up to here,
all systems are go.
You gently slide the amplifier around and
see no unattached wires hanging loose and
no stray strands shorting the loudspeakerconnection screws. Turning off the power
briefly, you tighten the screws with your
nail file or pocket knife and firmly seat the
two mike connectors.
Two mike connectors? You dash to the
other microphone-the one for the guest
speaker -and Eureka! It works! So while
a hastily recruited lodge brother talks into
the good mike, you identify the defective
channel at the amplifier by disengaging the
mike cable connectors one at a time and
noting when the signal stops. Then putting
your finger on that channel's now -exposed
single (Amphenol) or triple (Cannon) mike
input terminals on the amplifier, you get a
satisfying buzz from the speakers.
So you now know the amplifier channel
is good and the mike or its cable is bad.
K
ELEMENTARY ELECTRONICY
www.americanradiohistory.com
by Eugene F. Coriell,
Lt. Col. USAF -Ret.
By this time, the assistant manager has arrived. In no time at all, he sets up a spare
mike and waves good luck as he hastily departs to answer a paging call.
Pause Smiling. You heave a mighty
sigh. The MC looks ten years younger as
he confidently repeats his test routine-and
promptly ages again as the system howls
into feedback. As the guest speaker enters,
the MC tosses the ball of wax back to you..
So what now, Marconi?
Feedback, hmmm. Maybe in checking
over the amplifier connections, you accidentally advanced the mike pot? No, it's
OK but you drop it a bit. No dice. Another slight drop, and now the howl is gone,
and so is the needed volume. Could the
tone control have been jostled down into
the bass region where feedback is most
likely?
Nope, it's right in the middle of the range.
Then your eye falls on the MC's replacement
microphone and you notice it looks a bit
different from the original. In fact, it's a
non -directional unit and it's picking up some
of the loudspeaker output that was blocked
out by the original directional mike.
So you mentally tick off possible solutions
as the guest speaker is being escorted up the
aisle toward the head table. You could turn
down the gain to reduce system sensitivity
and have the MC buddy up to the mike to
compensate. Or you could raise the mike
higher on its stand and angle it downward,
hoping for a little instant directionality.
But wait a minute. Here comes the assistant manager again and he's carrying the
original mike. Beaming, he puts it back on
the MC's stand and explains he soldered a
broken connection in the connector receptacle. And gratefully you hear the clear,
ringing/tones from the loudspeakers, "Ladies
and gentlemen
Act II. In show business, they'd call this
happy solution a contrived ending. But now
let's put the shoe on the other foot in a
situation where any contriving may be strictly up to you. Let's say that, well in advance,
your lodge had the good sense to make you
their sound liaison man with the hotel. So
NOVEMBER -DECEMBER, 1969
..."
45
www.americanradiohistory.com
PA PATSY
you approach the manager via the publicrelations route and explain that the lodge
has asked you to offer cooperation in meet-
mastergain and tone -control pots set at midrange, you note down the position of each
mike pot for maximum volume before feedback occurs.
All mikes are on for this test. If this
volume is adequate in the empty room, you
figure there should be no howl problem with
a full house, since an audience absorbs
sound. Any additional volume needed then
is obtained by carefully inching up the
master gain without disturbing the individual
mike pots.
Listening critically, you note the absence
of hum but detect some crackling when
using one of the mikes. With the hotel man
nodding assent, you note that the cable is
snug in the mike head and that tapping the
instrument causes no crackling. But flexing
the cable as you walk toward its wall receptacle, you suddenly come to a point that
really makes the system bark.
Too many hotel dish carts have been
rolled over that cable, and your guide notes
ing the sound needs of the meeting. Since
this has probably never happened before,
you have thereby earned a good question and- answer session with one of his aides,
perhaps the hotel engineer.
For your particular table and seating arrangements, where will the mikes be plugged
in and what types are available? Where is
the amplifier located and what are the normal ranges of the gain and tone pots? Can
the mikes be seen from the amplifier location? Where are the speakers to be located?
Sometimes they are fixed in place, with some
or all hidden in the ceiling.
What is the range of movement of any
speakers that can be relocated if necessary
to reduce feedback or fill in
dead spots? And you ask to
have the hotel paging system
disconnected so that Maizie
at the switchboard can't come
booming in over the climax
of the guest speaker's best
joke.
Dress Rehearsal. You
then diplomatically ask to
try out the system with the
types of mikes you want,
placed where you want them.
You ask for the directional
type as feedback insurance,
Rear of S20 reveals two mike inputs of Am phenol type
for right, remote control connector at right of speaker
and this includes the auditerminals. Latter is for pots fo control mike volume.
ence traveling mike. With the
at
the need for a new one. The
other table mike seems to
cause pops, particularly if
Typical of public- address amplifiers is Precision Electronics'
Model S20. Power Monitor (extreme right) is neon
lamp which flickers when pots are set for desired output.
you get too close to it. Sadly
you agree replacement is in
order.
Trying out the traveling
audience mike, you notice it
causes howling when carried under any of the ceiling
speakers. You learn that, unlike some installations, these
speakers have no cut-off
switches. This means that
you'll want the mike man
practically pushing the microphone into the users' faces
i$
)PiLOcomAIIT
www.americanradiohistory.com
Macron=
Two directional mikes in
Shure's Unidyne series.
Left, Model 55S accepts cable
plug -in connector on threaded
collar; right, Model 545 has
cable -mounted connector.
to permit minimum gain setting to discourage feedback.
And this reminds you to have
someone assigned to that
mike, and also an operator
at the amplifier you'll main
tain liaison with as the sound
scout. Here you recall there
may be a union and you
make your arrangements with the hotel man
accordingly.
A Show For Sure. And now you foresightedly consider what to do if trouble occurs on the big night. If the hotel furnishes
an operator (this is unlikely in smaller establishments), you're in his hands. If the
lodge is graciously permitted to handle the
amplifier, any fast fix needed is likely to be
READ
-if
your baby
only because the emphasis
is on fast.
If the system conks out completely, maybe
some wise guy pulled the AC plug or a mike
connector. Or maybe the amplifier innocently blew a fuse. If the fuse isn't plainly
visible, you ask the hotel man for its location, along with a spare fuse which you tape
to the amplifier. The fuse has been known
TABLE
SPEAKER's NIC
Ml's NIC
-9
WALL SPEAKER
WALL
RECEPTACLE
MEMBERS'
MEMBERS'
MEMBERS'
TABLE
TABLE
TABLE
CEILING
CEILING
SPEAKER
SPEAKER
TRAVELING
WALL SPEAKER
MIG
Ideal public- address setup for banquet hall looks something like this, with wall and
ceiling speakers aimed well away from mikes. Properly set up and tested ahead of fime,
PA system should give no trouble when it's call on to deliver its all- important goods.
NOVEMBER- DECEMBER, I969
47
www.americanradiohistory.com
(DAD
PA PATSY
Leaving exposed cables and cords around banquet
hall is asking for trouble. Best bet is to tape down
all floor cables -those for microphones and speakers
-as well as all AC line cords with painters'
masking tape to avoid possible accidents.
to be hidden in the body of the AC plug.
And what if that old devil Hum should
loudly assert his dominion? You'll promptly
try reversing the AC plug in the wall socket,
and make sure the pot on any unused channel-including a phono input
all the
way off. You'll make sure any grounding
wire to the amplifier chassis is tight. If these
tricks don't work and the hum is bad enough
to warrant the interruption, you'll kill each
mike pot in succession. If this points up a
bad channel, you'll plug into a spare channel
if any, or commandeer the traveling mike.
Or you'll turn down the gain on the offending channel and ask the speaker to talk
closer to the mike to improve the signal-tohum ratio. But if the trouble is not in one
of the mike channels, you'll rap the amplifier smartly-just in case- and /or turn down
the tone control to minimum bass and ride
out the storm.
And on banquet night, you'll firmly tape
all exposed cables to the floor and all table
mike cables to the table legs, using 3 -in.
painter's masking tape. Thus do you prevent
mikes, members, and MCs from becoming
accident statistics. And thus does your overall planning assure the Royal Grand Potentate will truly lay 'em in the aisles- because
the sound system will lay no eggs.
-is
Individua! ce1 ing speakers in some halls are
equipped with cif -off switches to control feedback.
Reached with what hotel employees refer to as sky hcoks, switches can save the day for the PA patsy.
48
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
QUICKn-DIRTV
RTY
BATTERY-POWERED R
Herb Friedman, W2ZLF
Just about every organization can use a really portable PA system-one powered by batteries, not the AC line. For whether
it's a teen bash in the church garden, a CB or ham jamboree in the
boondocks (miles from AC power), or a school dance on the terrace
or roof, a battery-powered PA fits in neatly as a round peg in a
round hole.
Using a ten -buck solid-state amplifier as the basis, in less than
an evening you can throw together a lightweight, portable PA system
equal to or surpassing much commercial equipment. The performance of the unit you build will be tailored specifically for your needs,
because you select the quality of the ancillary equipment.
Options Galore. For example, if you need a very lightweight
portable PA of decent quality, you simply build the amplifier into
a small 8 -in. speaker baffle and use a decent -quality, 8 -in. speaker.
If you want a really top-flight system with excellent sound quality,
suitable for good music reproduction, you simply use a large PA
cabinet and high-quality PA- grade, 12 -in, speakers. You can tailor
the system to your individual needs because the amplifier itself is
basically of good quality, thereby allowing you to control overall
performance by your choice of speaker and mvcrophone.
The amplifier, McGee Radio type KA-500, is rated at 4.5 watts
output at 10% distortion. But unlike most solid -state amplifiers
NOVEMBER -DECEMBER, 1969
49
www.americanradiohistory.com
BATTERY -POWERED PA
I
which limit at the clipping point, the KA500 can be driven to 7 watts output, though
with considerably more distortion.
But even with the higher distortion, the
amplifier does a good job in PA service. (PA
system distortion is normally much more
than that of hi -fi systems.) The KA-500's input sensitivity is 15 mV, more than needed
for even low -efficiency microphones. Because a volume control is
used ahead of the amplifier
input, a high -level sound
source, such as a tape recorder, can be used without
fear of overloading the amplifier input. Finally, since
the idling current is only 50
mA at 9 volts, with peak current of less than an ampere,
the amplifier can be powered
by easy -to-obtain D cells.
use the microphone cable's shield as one side
of the power source, since the amplifier will
break into oscillation and may self-destruct.
Use a separate wire for the positive battery
lead even though it connects to the same
ground foil as the microphone shield. (Yes,
the positive battery lead is grounded in this
amplifier!)
Regardless of the cabinet and speakers
used, prepare the amplifier for installation
before you do anything else. All amplifier
connections are made directly to the pads
provided on the amplifier's PC foils; a pic-
Though miniature in size, PC
amplifier can pump out 7 wafts of
"voice power." That's enough for
most groups of under 250 people.
Easy Does It. A typical high -quality
portable PA assembly is shown in our schematic and photos. Even if you don't choose
to utilize the large cabinet and speakers
shown, use the electrical connections shown
in the schematic. In particular, don't try to
11
11
111111111111
AMP
11
11
IN
1111110111111
torial of the PC wiring is supplied with the
amplifier. Begin by connecting about 5 ft of
shielded mike cable to input pads. This
done, connect a red wire to the positive
power supply pad and a black wire to the
negative power pad.
111111
11
,,,:,,,1,.1111111,,,,,11,111,,,1 .::..::.. :..:::::....11,.u11,11:1,11,,,.,:,,,,:::1,,,,,::,1,:,,,,,,,,,,,11,11:,:11:::::1:::::,::::111,111,:1n
1
SPKR1
Simple? You bet it is. Just
add a handful of standard
parts to a ready -made,
goof -proof amplifier and
you and your PA will be
invited to many free
If
dinners.
you wish, a 9-
volt battery eliminator can
be placed across 111 to add
battery boost and charge
SPKR2
when unit is operated
near AC supply.
PARTS LIST FOR BATTERY -POWERED PA
Speakers (see text)
battery (6 D cells in series or equiv.
1 -PA
amplifier (McGee Radio KA -500 or
-see text)
equiv.) -McGee Radio Co., 1901 McGee St.,
C1- 100 -uF, 15 -V electrolytic capacitor
Kansas City, Mo. 64108
Open- circuit phone jack
Portable PA cabinet (Lafayette 4470126 or
J2, J3 -RCA phono jack
equiv.)
Pl, P2 -RCA phono plug
Misc.-Battery holders, terminal strip, screws,
R1- 10,000 -ohm, audio taper potentiometer
spacers, etc.
S1 -Spst switch (can be part of RI -see text)
B1
-9 -V
J1-
21-
11
11111111
1/110111111111111111111111111115
11
ELEMENTARY ELECTRONICS
50
www.americanradiohistory.com
Speaker Connections. To facilitate
changing speakers, solder the center terminal
of a phono jack directly to either the 8- or
16 -ohm speaker output pad and a wire from
the common speaker pad to the jack's
frame. Use the 8 -ohm speaker connection
for a single 8 -ohm speaker or for two 8 -ohm
speakers in parallel (4 ohms parallel impedence). Better results are obtained with
two 8 -ohm speakers if they are connected in
series to the 16 -ohm speaker output. Though
we show a single speaker jack in the photo,
a jack can be soldered to both the 8- and 16ohm pads if desired.
Assuming you use a portable PA case
such as the Lafayette 44 T 0125 shown in
the photo, remove the amplifier board from
the bottom of the cabinet by gently tapping
with a hammer on the underside of the
board. (Four small nails hold the board in
place.) Next, mount the amplifier to the
board using wood screws and 1/4 -in. spacers,
or a stack of washers, at each mounting
screw. You must use spacers between the
amplifier and the board, since the PC board
may crack if you try to mount the amplifier
directly to the board. Leaving room for a
terminal strip, install either three twin -D or
six single -D battery holders near the amplifier. See photo below.
Wire the battery holders in series so that
6 D -cells give 9 V output, and connect the
battery supply and the power wires from the
amplifier to the terminal strip. Make certain
you install capacitor Cl
across the amplifier power
wires at the terminal strip.
(If Cl isn't included, the amplifier can break into oscillation when the batteries age.)
Set the board aside.
Next install the speaker(s)
in the PA case. We suggest
quality PA speakers such as
the Lafayette type 44 T 0102,
shown in our photos. Locate
an area on top of the cabinet
for the volume control and
input jack as far as possible
from the speaker.
Better with Brackets. In
Here's upside -down view of 7 -watt amplifier that's heart
almost all instances the shafts
of battery- powered PA system. Connecting wires are soldered
on the volume control and indirectly to copper pads on printed circuit board;
put jack won't be long enough
center conductor of output plug is soldered directly fo foil,
(Continued on page 56)
making jack integral part of amplifier assembly.
SHIELDED INPUT LEAD
Amplifier
is
mounted directly
on wooden baseplafe supplied
with PA speaker cabinet. Be
sure shielded input lead is
long enough to reach
volume control when baseplafe
is inserted into speaker
cabinet. Class -D battery
holders are positioned like
soldiers for easy battery
replacement. Note that
there's plenty of room to add
battery eliminator for
117 -YAC operation.
BATTERY HOLDERS
NOVEMBER- DECEMBER, 1969
51
www.americanradiohistory.com
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for your money
from NRIAmerica's oldest and largest Electronic,
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ELECTRONICS
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NOVEMBER -DECEMBER,
1969
35
www.americanradiohistory.com
BATTERY -POWERED PA
Continued from page
51
to pass through the top of the cabinet. Rather
than undercut the cabinet, which would
weaken the area around the control and jack,
brackets have slotted holes, allowing the assemblies to be positioned so the control shaft
and plug shell are centered with respect to
the cabinet holes. The power switch can be
mounted directly on the cabinet or it can be
part of the volume control; the option is
yours. No pilot light is provided since it
would only increase battery drain.
After all cabinet components are mount-
Since volume control and input
jack shafts aren't long
enough to pass through
top of speaker cabinet,
mount these components on
control brackets as shown at
left using lock washers.
Secure brackets to
cabinet with #6 machine screws.
Do not use wood screws that
have insufficient length.
photo gives good idea of how long
input shielded cable must be to reach
volume control Rl. Be sure to staple
all leads to cabinet's wooden sides.
This
ed, install the amplifier board and connect
the cabinet components to the amplifier. If
you use two speakers, run polarized zipcord
for the speaker connection. Make the copper
wire the P1 "hot" lead (center conductor)
use Mallory type RB248 or RB 249 mounting
brackets to secure the parts. First, mount the
control and jack on the brackets as shown,
using a lock washer between the part and the
bracket. This done, drill a 3's -in. hole in the
cabinet to clear the control's shaft, and a
5/s- or 3/4 -in. hole to clear the shell of the
connecting phone plug.
Secure the control and jack assemblies to
the cabinet with flat -head #6 screws. The
and the silver wire the ground connection.
Note which speaker terminal has the copper
wire and connect a phono jack at the speaker with its center conductor connected to the
copper wire speaker terminal; this jack will
be used for connecting the second speaker.
Make certain the same terminal on the second speaker has copper wire, and that
this wire connects to J2's center conductor.
Mikes and Batteries. High -impedance
crystal or ceramic microphones are out for
this hookup, since the 10 -k volume control
loading will wipe out the mike's low -frequency response. Any dynamic mike with
an impedance in the range of 50 to 50 k
ohms will work satisfactorily; best results
are obtained with 250- or 600 -ohm mikes,
though the differences will be small.
While ordinary D cells can be used, the
alkaline type will give 3 to 5 times the life
per set of batteries. If you prefer an AC
power option, any 9-V supply capable of
delivering 800 mA peak current can be
used.
ELEMENTARY ELECTRONICS
56
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9/6
PRODUCT TEST]
HEATHKIT MODEL GR -681
Remote Control
Color TV Set
You can buy a good color TV just about
anyplace. But regardless of how much
you're prepared to spend, you can't buy a
great, production -run color TV. The only
way you can get truly great color performance is to build the set yourself . . . a
Heathkit color set; in particular, the Heath kit 295- square-inch, short neck, model
GR -681. (Short neck means that the color
set is no larger than a black -and-white TV of
equivalent tube size.)
Many of us in electronics, particularly
those who handle literally mountains of
equipment, have used the Heath color TVs
as the standard of comparison for color sets.
For the Heathkits produce neither garish
nor washed -out color; rather, they're known
for their soft, fully saturated color pictures.
In the GR -681 chassis the Heath people have
maintained their superb color reproduction,
and they have added excellent color stability through the use of automatic fine tuning (AFT).
A complete GR -681 color set really consists of three separate kits. The basic kit is
the GR -681 color chassis that includes a
wired remote control with power on /off,
and channel switching. The second kit is the
GRA -681 -6 wireless remote control, which
allows remote wireless control of the power
on /off, volume level, channel, tint, and color
(hue). The wireless control can be added
during the construction of the chassis or at a
later date, though for reasons we'll explain
later the wireless control should be added at
the time the chassis is built.
The third kit consists of the optional enclosure, supplied with a fully-assembled and
finished cabinet. For those who prefer custom mounting, Heath supplies custom cutout and mounting instructions in the assembly manual.
Features & Features.
You name it
the GR681 has it. Fact is, it even
sports a feature you haven't
thought of: a built -in dot
generator so the user can
do his own color alignment
or trimming. (And you
save approximately $35.00
each time you do your own
color adjustments.) Other
features include automatic
...
Completed chassis (tuner and
convergence panels are not
shown). High -voltage (horizontal) section (lower right),
supplied aligned, has performance certification sticker.
NOVEMBER -DECEMBER, 1969
57
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@/@
HEATH KIT COLOR TV
Finger points to motor drive for VHF tuner, which
is part of basic chassis package. Same motor and
wiring are used if you add wire less remote control.
CRT degaussing, a front -mounted color
convergence panel (behind the speaker on
a swing-down door), pushbutton and manual tuning, both 300- and 75 -ohm antenna
inputs, a low-pass filter for the tuner, and
-best of all -AFT.
By way of explanation, AFT is akin to
the AFC of an FM tuner. When the AFT
switch on the back of the brightness control
is pushed in, both the vhf and uhf tuners
are electronically locked to the correct tuning via varicap capacitors in the tuner oscillators. Even if you haven't adjusted the
manual fine tuning correctly, the AFT locks
the tuning. In fact, the manual fine tuning
is only used to check the AFT when construction is completed; it need never be
touched again. Since color reception is extremely sensitive to oscillator tuning, the
importance of AFT is obvious.
Critical IF amplifier printed- circuit board
is
supplied completely wired and aligned. Other
circuit board: are non-critical and user -assembled.
A small but convenient feature is an audio
output jack for connection to your hi -fi
equipment -this, incidentally, in addition to
the normal speaker output jack.
Can You Build It? Naturally, when you
consider that the GR-681 chassis kit represents $500.00 worth of individual parts,
you might have some reservations about
tackling a color TV kit. Fear not, for the
GR -681's assembly manual is perhaps the
finest kit manual ever produced, as is the
assembly layout. It is so good, and so easy
to follow, that a section which appears to
be picked up from an earlier kit sticks out
like a sore thumb. This is the convergence
panel, which has a few components that
barely fit into plate. Luckily, this problem
is not true anywhere else in the kit. Further,
the convergence panel is non -critical and
you won't go wrong.
As long as you have the ability to read,
and you use two proper-wattage soldering
irons, you will end up with a working color
set. Fact is, proper soldering is the key to
construction. Use a 40- to 50 -watt iron with
a Vs- or '46-in. chisel tip on the printed circuit boards, and a 100- to 200 -watt iron or
250 -watt gun for the chassis connection$.
You can't get a good chassis connection
with a 40 -watt iron, and a high -wattage iron
or gun will ruin the PC boards. Consider the
cost of the correct soldering irons as part
of the kit cost.
Actually, all the critical work has been
done at the factory. The vhf and uhf tuners,
the IF amplifier board, and the high-voltage
section are supplied completely factorywired and aligned. You assemble only the
color and sync circuit boards, convergence
panel, power supply, and interconnections.
Several factory- assembled wiring harnesses
are provided.
Wireless Control. When wireless control
is used, the tint and color controls are adjusted by small motors mounted on the backs
of the controls. The motors are supplied with
the remote control kit, not the color chassis,
and it's one frustrating and difficult job to
substitute the motor controls after the kit
is completed. Hence, it's advisable to purchase the remote control kit with the chassis
kit. Then, when you get to the installation
of controls FJ and FD, you can install the
motor controls from the wireless control kit.
The remote control takes roughly 20 minutes
to install if you have the motors in from the
beginning. Otherwise, you suffer through
an hour or two of sweat and tears.
58
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
zs
.
Remember, it takes time to build a color
set-from 25 to 40 hours, depending on
your experience. And don't forget to add
another hour or so for first color alignment.
We say first alignment, because unlike a
store- bought color set with a short burn-in
time that can produce color drift, you'll be
wanting to allow the Heathkit to burn -in for
two weeks. After this, you'll again align
the color circuits, obtaining color performance that will make everyone jealous.
Once you get the hang of the color convergence controls you can do a color touchup alignment in about 15 minutes. Do one
every six months and you'll maintain great
color reception.
The user's color adjustments are really the
heart of the GR -68 l's performance. Using
only the built -in dot generator -the only test
Tuning meter built into wireless control makes for
easy adjustment. You simply press transmitter
button and adjust coil for maximum meter reading.
equipment needed for any adjustment -you
very quickly become expert at adjusting color convergence. Color loses its mystique,
becoming just another box with controls. At
any time you are sufficiently competent and
confident to reach in back of the set to make
a fine color correction or convergence adjustment.
Of course, because of the multitude of
controls common to color TV, the question
arises, "Isn't it difficult for a newcomer with
no experience in color to get a good color
picture ?" The answer is no, due entirely to
the excellent manual. Before anything is
touched all controls are preset as described
in the manual. When power is first applied
you have something on the screen and are,
in fact, well inside the ball park.
Construction of the color chassis was
strictly "no sweat." It worked as soon as we
applied power. Our only problem was that
the tuner conked out after 15 minutes operation. But from the rather good, color-illustrated service manual, we were able to
isolate the trouble. (The tuner was later
replaced under Heath's liberal replacement
policy.)
Performance. As we said previously, the
color reception is great -magnificent, if you
prefer that term. The set is rock stable, and
is less sensitive to interference than a good
quality b&w set we used for comparison.
Both H and V circuits locked up hard, and
at no time since the set was first turned on
have we had vertical roll or horizontal
breakout.
'Ile convergence panel, as we mentioned
earlier, swings down to let you make adjustments from in front of the screen. It also
contains the vertical, AGC, color -killer, sync,
and dot-generator controls.
An 4djustable color killer insures b &w
reception that is really black and white.
Even the sound is notably good. In fact,
no matter how we consider the GR -681,
great color reception is synonymous with
Heathkit.
Last, the GRA- 681 -6. This wireless remote control takes two or so hours to build
and plugs into the color chassis after a small
wiring harness is added (and this harness
should have been made part of the original
assembly). It is an ultrasonic receiver that
responds to six ultrasound frequencies generated in a battery -powered, hand-sized
transmitter. Each frequency determines a
particular function or functions. Four frequencies determine the rotation of the tint
and color controls; the fifth frequency
switches channels; the sixth frequency controls the receiver's sound level and power.
The remote receiver has a built -in tuning
meter for alignment of each channel. Total
alignment time is five minutes or less; you
simply peak six coils, in turn, for maximum
meter indication when the matching transmitter button is depressed.
Summing Up. As we said, if you want a
great color TV set, you have to build a
Heathkit.
Price, as mentioned before, is $500.00,
and for additional information write to
Heath Co., Dept. 139 -68, Benton Harbor,
Mich. 49022.
NOVEMBER-DECEMBER, 1969
59
www.americanradiohistory.com
Is interviewed by cocnselor in neigh.
borhood employment center. In=ormotion obtained is later fed to 18M 1130 computer.
Applicant'
In an age when problems caused by
overpopulation are more acute than
ever, the major role that computers play
in solving these problems can hardly be
overestimated.
Typical is ways the computer enters
into the areas of unemployment and
under-employment. For example, now
local or neighborhood employment
agencies and social servi_es can get in
touch with a central employment agency
service that gathers data on job opportunities from around the country and
matches them up with their local clients.
The neighborhood employment agency
is linked electronically by a keypunch
system that feeds all the qualifications
of the client into a computer at the central agency. The computer, in turn,
sends back all informaron about jobs
and training opportunities or other data
that the client needs.
Within seconds information that includes duties, salaries, location, requirements, starting date, narre of employer,
and all other employment information
is available. The central computer also
automatically demands verification from
time to time of all jobs filled or not
filled. In this way the computer's memory bank is kept up to da-e, and precious
weeks of waiting and writing are eliminated.
Information on jobs is supplied to the
central agency by various state and
4kt+
i8U511WICK dt'l's.
ELEMENTARY ELECTRONICS
fin
www.americanradiohistory.com
Brain of IBM 1130 computer at agency's data processing center. Machine searches its memory bank, supp lies information in seconds.
private organizations along with individual employers who are looking for
specialists in various fields. An applicant at the local employment agency
may choose up to three occupational
code numbers, covering such jobs as
receptionist, bookkeeper, typist, clerk,
claims adjuster, mail clerk, bank clerk,
nurse, truck driver, carpenter, painter,
and welder, to name only a few. These
code numbers are used to trigger the
computer's memory bank that has previously recorded data on job openings.
Information sent back from the central agency supplies the local employment center's client with the necessary
information that he needed. Nor does
the system stop here. For having found
the unemployed person a job, it also follows up on an applicant's progress after
placement and training.
Our photos show several of the steps
involved in matching available applicants with available jobs in the Greater
New York area. Basis of the entire
operation is an IBM 1130 computer,
which explains why we call the process
job- hunting the 1130 way.
A tongue -in -cheek conclusion: No
longer does the pessimistic Malthusian
theory of the need of war and famine
for overpopulation hold meaning as
long as the machine and especially the
computer come to the rescue
-C. Hansen
ow"
11111.100fti
Above, right, applicant lakes test to determine aptitude in
math and English. When tests are completed, finding; are
coded, then speeded to 113G computer (below). Nambers
are key to operation; computer deals in numbers, not names.
Below, left, neighborhood employment agency in poverty
area is in constant contact with main computer center. Local
businessmen are told of computer's employee-finding potential (center); counselor instructs job applicants fright).
NOVEMBEfl-DECEMBER, 1969
61
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Here's a job you can keep! A U.S. Steel technician
removes a latent charge from a 17 -ft. high
accelerator, part of a million -volt electron
microscope. But don't worry about him being
zapped. After unit is fired, almost all of the
charge is used up- efficiency is good!
entists at United States Steel's Fundamental Research Laboratory soon will
take a penetrating look into the unknown
and unseen secrets of the moon. To do so,
they'll bombard lunar specimens with a
stream of electrons on the nation's most
powerful electron microscope.
The million -volt super tool, located at
Monroeville, Pa., is key instrument in an
unique collaborative study of lunar surface
material. The National Aeronautics and
1
000 -kV
Peek-a -Boo
Space Administration has contracted for the
study with U.S. Steel; Case Western Reserve
University, Cleveland; and the University
of California, Los Angeles.
Arranged by Professor S. V. Radcliffe of
Case, the cooperative investigation will combine the efforts of experts in several scientific
disciplines in order to ensure its complete
success. Experts in petrographic analysis,
headed by Professor D. T. Griggs of U.C. L.A., will select samples of greatest interest
for study which will then be prepared for
transmission electron microscopy by Professor A. H. Heuer at Case.
Unlike conventional microscopes, the
unique instrument has the capability of looking completely through a specimen with its
electron beam and not just at a magnification of its surface. Scientists are eagerly
anticipating the opportunity of examining
the entire depth of thicker -than-normal specimens of the lunar material. The scientific
value of thicker specimens is that they are
more truly representative of the natural state
of the material; they are easier to prepare
and far more accurate appraisals can be
made from them.
To attain its vast power, the microscope
uses a million -volt accelerator. Though the
accelerator stands 17 feet high and weighs
15 tons, its precision stabilization system
maintains the DC voltage constant to within
0.0004 percent. An accelerated stream of
electrons is fired through the microscope's
magnetic lenses at approximately 94 percent
of the speed of light. This velocity gives the
electrons a penetrating power of up to ten
times that of beams used in standard electron microscopes and makes it possible to
examine much thicker specimens.
ELEMENTARY ELECTRONICS
62
www.americanradiohistory.com
COVER STORY
UTILITY
AMPLIFIER
Only crie IC, but you can get up to
biter than
b t Ed
a
watt output
Morris, W2VLU
HOW MANY TIMES hale 'It_ been
frustrated because you ,gad to make
do with a compromise -en, im an experiment because you dión t have the
one that was called for? Noe undoubtedly know what we mear. You saw an
article describing an e:cperimeynt you
would like to try tha: deperd_ on a
small amplifier. So you hac to improvise by borrowing ; ?) the murçgster's
phono or your wife's trarìsislcr radio.
End result was that you "curd up with
Excedrin headache no. 279 and became an expert at defining frustration.
Seriously, moss experienced servicemen and experirn iters are well aware
of the true value of a good universal
utility amplifier for test purposes.
Many, in fact, keep one on hand for
just such applicat ons. The neophyte,
however, may no- realize how handy,
and at times atsolutely necessary,
such a unit can le. Therefore, for the
relative newcomer in electronics, here
NOVEMBER -DECEMBER, 1969
63
www.americanradiohistory.com
UNIVERSAL AMPLIFIER
are the details on how to build a top -notch
utility amplifier for the embryo test bench.
Also, building this up -to -date, solid -state Universal Utility Amplifier, should give any old
pro excuse enough to retire his older,
vacuum-tube versions.
Reasonable Power at Low Cost. Our
utility amplifier can be built for just about
$15.00, and that is based on having to buy
all new components. When using the selfcontained battery pack of four inexpensive
AA cells, it delivers audio power in excess
of 300 milliwatts. This same basic unit can
be modified to provide a maximum power
output of one watt, but more on that later.
The integrated circuit (IC) we used has
fairly high sensitivity. When operated as a
class B amplifier, with just 35 millivolts input, an output of about 150 milliwatts can be
developed when using a 3 -volt supply, or 400
milliwatts when using a 6-volt supply. If a
CA3020A is substituted for the CA3020 we
used, an output of slightly more than one
watt is available when a 12 -volt supply powers the unit.
The amplifier has both high- and low impedance inputs that are switch -selectable
from the front panel. The high input has an
impedance of 55,000 ohms, while the low
input impedance is 1000 ohms.
With just a few hand tools you can easily
build our IC utility amplifier in three to five
hours. Considering its small size and portability in contrast to its large performance, it's
an extremely useful, versatile, and handy
piece of equipment to have on the bench.
How It Works. An RCA integrated circuit is the basic component of the complete
amplifier. Both the CA3020 and CA3020A
are multifunction, low -cost, wide -band ICs
that can be used as power amplifiers and
drivers in portable and fixed communications
equipment. They are designed to operate
from a single supply voltage which may be
as low as 3 volts. The maximum supply
voltage is dependent on type of circuit operational requirements.
As used in the Utility Amplifier, the IC
comprises the total complete amplifier assembly without requiring any other transistors
or diodes. It serves as buffer, phase inverter,
driver, power amplifier, and voltage regulator-and all in that little metal container.
A few additional external components are
required to couple audio signals and to set
the operating conditions for the internal circuitry of the IC.
A functional block diagram (below) of the
IC, indicates the relationship of its various
sections. The voltage regulator is of basic importance in its operation. It provides accurately controlled voltages to the differential
amplifier so that the proper idling current
for the class -B operation is effected in the
output stage. The differential amplifier operates in a class-A mode to provide required
gain and phase inversion for the class -B
driver and output stages.
The drivers are emitter followers which
shift voltage levels between collectors of the
differential amplifier transistors and the bases
o1` the output transistors. They also provide
the drive needed by the output transistors.
The output -stage transistors are large, high current devices and are able to deliver peak
currents better than 250 mA. The emitters
of the output transistors are brought out to
pins 5 and 6 so that more complete stabilization of the idling current of the amplifier can
be effected.
By adding resistors externally between
pins 5 and 6 to ground, effectiveness of
internal DC feedback supplied to the bases
of the differential amplifier is enhanced.
To visualize the operation of this "mightymite" package, let's trace a signal from the
input jack of our amplifier to the output
through its self- contained speaker. Audio
AC INPUT TO TERMINAL.
No.10
PUSH PULL
OUTPUT
TO
LOAD
ALTERNATE AC INPUT
TO TERMINAL No. 3
Function block diagram for
CA3020/CA3020A lCs shows
relation of voltage regulator
to differential amplifier and
indicates signal flow through IC.
CA3020 and CA3020A are
identical except for power output;
CA3020A accepts higher voltage
and produces greater output.
ELEMENTARY ELECTRONICS
64
www.americanradiohistory.com
Carrying case opened, showing
location of batteries. Three AA
cells mount in clips in
cover to clear controls.
signals, fed in through the
high -impedance input (J1),
are coupled via Cl to the input of the buffer amplifier.
(C1 also blocks buffer-amplifier DC from the input of
differential amplifier.) Output of this stage (pin 1) is
coupled to the input of the
differential amplifier (pin 3)
through the gain control (R2)
and capacitor C3. Resistor R3 establishes
the operating conditions of this stage.
When input channel selector switch S2 is
in Chan A position, the high -impedance
input is selected. When S2 is placed in
Chan B position, audio signals fed in through
low- impedance input terminals BP1 and BP2
are coupled through R1, which serves as
gain control for low- impedance input, to C3.
They are then fed to pin 3, the input connection to the differential amplifier.
Because of the extended frequency range
of the CA3020/CA3020A ICs, capacitor C4,
a high -frequency AC bypass capacitor, is
connected to pin 3 to prevent oscillation at
TO
R4
C4
BI(-)
ICI
TO Bl(+)
R3
CI
C3
TO
JI
stray resonant frequencies of the external
components, especially the output transformer. Pin 2, the other input to the differential
amplifier, is placed at AC ground potential
by capacitor C5.
Output of the differential amplifier is
internally connected to the driver and from
the driver to the output transistors in the
output section of the IC. The output signal
appears at pins 4 and 7, where it is coupled
to the speaker through transformer T1,
which matches collector -to-collector impedance of the output stage of the IC to the
voice coil of the speaker. As previously dis-
cussed, R3 stabilizes the push -pull power
stage.
Mechanical Construction. For greater
versatility and applicability, we made our
amplifier assembly portable. The Kodak
M2/M4 camera case that we selected to
mount our Utility Amplifier in serves very
well as a housing for the unit. This lightweight, foam-padded interior, rigid body case
makes an ideal housing for many small electronic instruments. We purchased ours from
the photographic section of a local department store for less than $5.00.
Start the mechanical construction by
mounting the battery holder in the upper
half of the case, close to the hinge. It should
be located so as not to interfere with switches
and controls, etc., when the case is closed.
A red paint marker (use some of your best
girl's nail polish) on each of the battery
clips near the positive end will ensure that
the batteries are properly inserted.
Front Panel. The front panel is a 31/2 x
Amplifier circuit card detailing location
of components. Wiring on underside of
board can be hard wired or etched foil.
piece of G -10 grade, epoxy -glass
printed circuit board. The copper -clad side
is used as chassis ground. Epoxy glass sheet
can be easily cut and drilled with simple
hand tools.
Layout and drill all of the holes for the
components that are mounted directly on the
panel. The large hole for the speaker can be
cut easily with R hand nibbler. An alternate
method to make the speaker opening and
grille would be to drill a series of closely
spaced holes in a pattern similar to the perforated metal grille we used in our model.
Thoroughly clean the copper side of the
61/2 -in.
NOVEMBER- DECEMBER, 1969
65
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UNIVERSAL AMPLIFIER
board after all the drilling has been completed. Either copper cleaner or an abrasive
cleaner such as Comet can be used. This
prepares the surface for easy soldering.
Gently sand the epoxy side of the board with
a medium -fine grade sandpaper to condition
the surface for painting.
Wash the board and thoroughly dry it before painting. Follow manufacturer's directions for applying the spray paint. When
spray -painting it's best to apply several light
coats of paint instead of a single heavy coat.
Be sure to allow each coat to dry completely
before applying the next. Fora really professional job, "fog" on the first few coats,
and follow this up with an additional 3 to 5
light shiny coats. The results are well worth
the extra work.
R«««m,«««««««««w«
«««l«««
.«.«mmt««««««««« «i««m«mmni«««
««««««
Add a finishing touch to the front panel
by applying dry-transfer letters or decals. If
you use dry-transfer letters allow the final
coat to harden overnight before applying the
characters. This will prevent the possibility
of a slightly tacky finish from adhering to
the letters on the transfer sheet. Apply a clear
acrylic spray as a finish coat to protect the
lettering from abrasion. Be sure the first
coat of acrylic is very light, since excess
solvent in a heavy coat could dissolve the
transfer letters or decals.
Electrical Construction. Although the
layout of the amplifier isn't critical, consideration should be given to the high gain
and wide bandwidth of the IC. It will oscillate if there is sufficient coupling between the
input and output circuits due to stray wiring
capacitance. The newcomer would be wise to
follow our layout. The more experienced
experimenter may want to modify the layout
to best suit his needs. In any event, good
mum«««««««m««««m«««r«««««m««««««m«n«««««n««««««««i««mmu«
«««i««««««i«««
mi«««wn«««t«m««
S1
(SEETEXT).
61
BOTTOM VIEW
PARTS LIST FOR UNIVERSAL UTILITY AMPLIFIER
B1
volt battery 4 -AA 1.5 -V alkaline cell batSi, S2 -Dpdt miniature toggle switch (Lafayteries (Lafayette 9976294 or equiv.) (see text)
ette 9976162 or equiv.)
BPI -Red binding post (Lafayette 99T6121 or
Spkr-21/2 -in.,
10 -ohm speaker (Lafayette
equiv.)
9976097 or equiv.)
BP2-Black binding post (Lafayette 9976120 or
Output transformer; 125-ohm CT pri., 8-
-6
equiv.)
C1- 0.1 -uF,
75 -V ceramic disc capacitor (Lafayette 99T6069 or equiv.)
C2- 15 -uF, 25 -V electrolytic capacitor (Lafayette 3478459 or equiv.)
C3, C5
-uF, 25 -V electrolytic capacitor (Lafayette 9976054 or equiv.)
C4- 0.01 -uF, 75 -V ceramic disc capacitor (Lafayette 3376905 or equiv.)
ICI -RCA type CA3020 (see text)
J1 -BNC chassis mounting connector (Lafayette
3272122 or equiv.)
Rl, R2 -5000 -ohm potentiometer, audio taper
(Lafayette 3371121 or equiv.)
R3- 510,000-ohm, 1/2 -watt resistor
R4 -0.56 -ohm, 2 -watt resistor
-6
Tlohm sec. (Lafayette 3378571 or equiv.)
1-Battery holder for type AA cells (Lafayette
3475009 or equiv.) (see text)
1- Carrying case (Kodak M2/M4 camera case
or equiv.)
-31/2
x 61/2 -in. G -10 epoxy glass printed
circuit board (cut from Lafayette 1973704
sheet or equiv.)
1-1.3 x 1.9 -in. piece pert board (cut from
Lafayette 1973606 or equiv.)
1 -Heat
sink for IC (Wakefield NF-209 or
1
equiv.)
Misc.-Spray paint, sandpaper, bolts, nuts,
wire, solder, hand tools, dry transfer letters
or decals, push -in terminals, etc.
5.11
IR
ELEMENTARY ELECTRONICS
66
www.americanradiohistory.com
practices for high- frequency wiring should
be followed. 'Nough said?
Mount the potentiometers, switches, and
input terminals and jack on the front panel
which is detailed in our photo. The speaker
is mounted with machine screws. A 21/2-in.
square piece of perforated aluminum is
mounted between the speaker and the front
panel to serve as a grille, unless you drill
your own grille directly in the epoxy glass
board as mentioned earlier.
Transformer T1 is mounted as shown in
our photo by soldering its mounting tabs to
the copper side of the board. Clean the tabs
so that the solder will flow evenly on them.
Perform the soldering quickly, using a
medium- powered soldering iron (50-100
watts). Remember, too much heat will blister the paint on the reverse side of the board.
Next, mount the balance of the components on a 1.3 x 1.9-in. piece of perf board
as shown in our photo on page 65. All
low- powered soldering iron (20-50 watts)
should be used for this operation. Complete
the soldering as quickly as possible to avoid
too much heat -this could damage the IC.
After the various components have been
positioned on the card and wiring links have
been made between them, check for errors
in circuitry before soldering connections.
Also, check that electrolytic capacitors have
been properly polarized, that there are no
shorts, and that the wiring to the IC is correct, thus avoiding having to replace components. Once they're soldered it's hard to
remove them, especially ICs.
The completed card is mounted on the
rear of the front panel, as shown' in Fig. 3.
We used '/a -in. squares of plastic, cemented
to the panel as stand -offs and then cemented
the circuit card to them. We used this method, rather than screws, which would interfere with the lettering on the operating side
of the front panel. Now connect the mounted
circuit card to the controls
and other components on the
panel Capacitor C2 is wired
in at this time. Use very
SPKR
flexible stranded test lead
wire for leads from the battery holder to the amplifier.
Check the completed assembly for possible shorts,
cold solder joints, etc. Insert
the batteries in the holder,
making certain that polarity
of each of the cells is correct,
and you are ready to test the
Ji
unit. Connect the input to
Si
R1
TI
an audio oscillator (if none
is available, a microphone
and
Rear view of front panel locating controls, speaker,
will do, or the output from a
circuit board on which IC and its components are mounted.
tuner). Turn the amplifier on,
letters.
transfer
with
marked
and
painted
Front panel is spray
and if all is well you should
music!" Be sure to check
"beautiful
hear
excepthe
with
components
of the remaining
inputs.
low
and
high
tion of C2 are mounted on this card. Capac- both
input
works, check the input
one
If
only
congain
between
itor C2 is self-supported
that doesn't work.
the
channel
for
circuit
trol R1 and BP1 by its leads.
or replace any
wiring
to
corrections
Make
perf
on
a
amplifier
Though we built the
inputs operboard, an interesting variation would be to defective parts. If neither of the
then for
polarity,
for
battery
check
first
ate,
technique.
construct it using a printed circuit
short cirpossible
or
for
joints,
ELEsolder
of
cold
issue
'69
/October
September
The
cuits that may have developed when the
MENTARY ELECTRONICS contains an article
circuit
panel was inserted while mounting the
of
a
printed
that details construction
board which can be used as a guide to assembly in the case.
This done, check the wiring once again.
technique for making this one. Push -in clips
all
are used to mount components to the board If all these tests reveal no errors, check
IC
the
to
connected
components
the
external
and as terminal points.
correct
Use a battery clip as a heat sink when with an ohmmeter to be sure of their
circuit
soldering the IC circuit leads. A well-tinned, value. If all checks prove OK and the
67
NOVEMBER-DECEMBER, 1969
www.americanradiohistory.com
UNIVERSAL AMPLIFIER
wiring is correct in every respect you will
have to replace the IC.
Higher Output Power. As mentioned
earlier, should you prefer more than the 300
milliwatts output power, the power of our
basic amplifier, you can raise it to 550 milliwatts or even 1 watt very simply. To raise
output to 550 milliwatts, all that's required
is to increase the battery voltage from 6 to
9 volts. This can be done by substituting a
standard 9 -V transistor radio battery for the
four AA cells.
It's possible to achieve the 1- watt -or-better
output by using a CA3020A IC in place of
the CA3020 and raising the battery voltage
to 12 volts. Do this by doubling up on the
AA cells, using 8 ,rather than 4 (you will
need an additional battery holder to do this).
The CA3020A has a higher voltage rating
than the CA3020. This permits using 12 -V
supply instead of 9, the maximum for the
CA3020 in push -pull class B operation. It's
,W.....1..1..,w.w1..1..111..wMw..,.11.1...w.1w.....111ffill.,......ww,.w1
the higher voltage that provides the increase
in output power. The CA3020A has the
same pin connections as the CA3020 and
can be placed in the circuit without having
to change any of the wiring.
A word of caution: if you elect to make
your Utility Amplifier with the higher output
be sure that the speaker and output transformer you use in the output circuit can
handle this much power. We suggest that in
the event you go to the higher output, you
bring out the output leads through a suitable
jack or binding posts on the front panel. The
output leads are connected to pins 4 and 7 of
the CA3020A.
Now that you've assembled this easy -tobuild, simple, useful, and inexpensive portable Utility Amplifier, we're certain you have
thought of its many potential applications.
Some of the uses that come to mind immediately are the audio amplifier of a phonograph; a low- powered stereo amplifier (using
two of the amplifier assemblies); the modulator section of a low- powered amateur
transmitter; or, as an amplifier in intercom
systems. No doubt you can dream up other
applications.
...........................................in...w....,111.111. .11.1.,............,....,1A....1111...,...,11M..IP
the big push
IN read OUT
A.B. Dick Co. officials predict print -out bottlenecks in computer data transmission networks
will soon be a thing of the past. Reason: the
company's new Videojet 960 printer, which employs an electronically controlled stream of ink
droplets to print 3000 words a minute-15 times
the rate of printers now in use.
Stock transactions will take place at
some of the fastest rates in history once
automated quote boards are installed on
the Amex Trading Floor. Above, Frank C.
Graham, Jr. (left) and James J. Maguire
of Amex discuss automated quote board.
68
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
Q/3
PRODUCT TEST
KNIGHT -KIT MODEL KG -392
Electronic Rhythm Section
Combo Sideman
Among the things that are more fun doing with someone else is music. While
it may be fun to play alone, it's a lot more
pleasure if you're part of a crowd. But if
you can't rustle up a rhythm section for some
practice, you can do the next best thing by
creating your own aggregation with Knight-
Kit's Combo Sideman.
An electronic device that synthesizes a
drummer with bass drum, snare, and high hat cymbal, the Knight-Kit KG-392 Sideman consists of a rather flat metal enclosure
having rubber feet. It provides six switch selected rhythms tailored primarily for modern music (no waltzes!). The six rhythms
are shown in the accompanying chart. A
second control determines the rhythm's
tempo, while a third control establishes the
volume level. Internal trimmer potentiometers allow the user to shift the overall range
of the tempo and volume controls to suit
personal preference.
A pushbutton switch provides for start/
stop (on and off), while a second pushbutton labeled solo provides a continuous "drum
roll" as long as the button is held down.
Three phone jacks provide the signal output,
on /off footswitch control, and footswitch
control of the solo effect. Supplied with one
pre -wired output cable and one footswitch
that can be used for either on /off or solo, the
unit is powered by a transistor radio type
9 -volt battery. A handy clip inside the cabinet retains a spare battery.
A Look at the Circuit. The sounds created by the Sideman are actually shaped and
frequency -equalized noise -the same technique as used in all other rhythm generators
regardless of price. The bass drum effect
is a voltage -keyed oscillator. A single transistor is biased almost to the point of oscillation. When a voltage pulse is applied to the
base circuit, the oscillator is "kicked on"
by the pulse and then decays relatively slowly as the oscillations die out.
A three -stage transistor circuit generates
"white noise" for the snare and cymbal effect. The noise is fed to a tuned amplifier
which is held at cut -off. When a voltage
pulse is fed to the base of the transistor
amplifier, the amplifier is turned on. The
noise signal is then passed through the tun-
The circuit board for the
Knight -Kit Combo Sideman is
¡am packed with oscillator and
multivibrator circuits. Be sure
you handle this board with care to
avoid damaging the components.
Just imagine building this kit
from scratch as a construction
project -it'd never get done.
NovEMaEa-DECEMSER, 1969
www.americanradiohistory.com
V®
KNIGHT -KIT COMBO
ing circuit which shapes the noise frequencies to sound like a snare of high -hat cymbal, depending on the degree of decay. The
voltage level of the applied triggering pulse
determines the amplifier's output level and
decay rate, which is differentiated by the
listener's ear as a snare or cymbal.
Five Multivibrators. The rhythm is detemined by a "clock" multivibrator and four
multivibrator frequency dividers. The clock
multivibrator (MV) provides what can be
called sixteenth notes. The clock's output
feeds a MV frequency divider which generates square -waveform eighth notes. Depending on which of the MV collectors the
divided signal is taken from, the MV output
"starts" either on the first Me or on the second Ms. The same thing is done through
three more dividers so that at the final MV
the output pulse is equal to a whole note.
The assorted MV outputs are then combined through the rhythm switch to provide
the desired rhythm. For example, in Position B the first MV divider provides '/8 -note
high -hat effect, while the 'A note triggering
provides the bass drum and snare on every
second high -hat beat.
Since the effects are triggered by the leading edge of the MV waveforms, the MV out-
Position A
Position
Position
B
C
Wide parts layout combined with preformed wiring
harness totals up to 45 minutes of assembly time.
Troubleshooting is easy because you see everything,
puts really provide the delay necessary for
keying in the appropriate effect at the right
time. In the Position B illustration, the
rhythm selects the '/s -note MV output to
key in the high -hat cymbal. The snare and
bass effects are keyed by the MV divider
following the '/s divider, so they are keyed
in on every second beat. When we get to
Position E, which is somewhat complex,
feedback is thrown into one MV divider to
produce an "unnatural" time
delay of approximately 14.
While the idea is somewhat
complex, the actual circuitry
is not.
The outputs from the three
effects circuits are combined
in a preamplifier and fed
Position D
through a volume control(s)
to the output jack. The output
level is more than sufficient
for all instrument amplifier
inputs, and will be adequate
for some extra -sensitive hi -fi
amplifier auxiliary inputs.
(Continued on page 100)
Position E
Position F
Just in case you're not a boob like
the Editor, here are the rhythms
generated by the Knight -Kit
KG -392. If you can read music,
start humming: otherwise, listen
and enjoy as we boobs do!
70
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
what makes
SUPER
by Len Buckwalter, K1ODH
The road to radio reception is littered with
circuits that electrified the world, had a
flash of greatness, then faded in the zenith
(and RCA, too). One of the first was the
Branly detector -merely a glass tube filled
with metal filings that clung together when
they picked up a radio wave.
This was vastly improved by
Marconi who added a clapper to strike the glass and
shake loose the filings. Now
the receiver could respond to
Morse code. Soon there was
the cat's whisker, the TRF
(tuned radio frequency) and
regenerative receivers. But
today these circuits are practically museum pieces except
for SWL receiver projects in
this magazine.
All were short- circuited by
Major Edwin Armstrong's
World War I development of
the superheterodyne receiver.
You can measure its success
by counting the superhets
you probably now own. It's
the standard in the TV set,
FM radio, transistor portable, car receiver and table
radio. If you're a ham,
CBer, SWL or radio -control
fan, chances are your receiver is a superhet. The same is
true if you run a radar,
loran, aircraft navcom or
just about any receiver that
picks up radio signals and
turns them into audio, video
or needle indications. Why is
it so super?
Wide as a Barn Door.
It goes back to quirks in the
receivers" tuning circuits, mainly the variahle capacitor- and-coil combination. These
components, hopefully, select one frequency
from many (in the antenna, for example)
and slice away undesired signals. How well
any tuning circuit can isolate frequencies is
a measure of selectivity.
Simple tuning circuits suffer
poor selectivity for at least
three reasons: unfavorable
tuning ratios; resistance introduced by the coil; and operation at high frequencies.
An example of the first
problem- tuning ratio-is
apparent in the photo of Fig.
1. It's the dial of a cheap
transistor radio. Notice how
the numbers are spaced. Between 6 and 7 (600 and 700
kHz) there's about onequarter inch; and from 11 to
16 there's also a quarter -inch
span. Signals in the upper
end of the band, therefore,
are apparently compressed.
How does dial crowding occur? The reason is in the
tuning rate of the variable
capacitor in relation to its
companion coil (Fig. 2). At
the high end, the tuning rate,
or speed, of the variable
capacitor becomes relatively
faster than for the low end
of the band. Thus, for a
given amount of dial twisting, more stations whiz by
at the upper end. There are
technical solutions to the
problem.' There's permeability (coil) tuning (done in a
car radio), band-switching
'ïI
NOVEMBER-DECEMBER, 1969
www.americanradiohistory.com
SUPER SUPERHET
the coil (in expensive receivers) or selecting
whole tuning circuits for each frequency
(done in TV tuners). But these remedies
are costly, only partly effective, or both.
The second big problem resistance-also
lowers tuning efficiency at the higher end of
a band. Any tuning circuit resonates to a
frequency by virtue of an LC ratio; there's
a given amount of coil inductance (L) to
capacitance (C). A signal on a particular
frequency may be tuned either by a large
capacitor and small inductance
vice versa. But here's the flaw. If a circuit uses
a relatively high inductance (more L than
C), efficiency is poor. It's because the resistance of the coil becomes a major value in
circuit operation. Resistance not only causes
a broadening of the circuit's selectivity, but
a drop in signal voltage. (See actual scope
tracing in Figs. 3A and B.) You'll notice it
when you tune a table radio to the high end
of the band-unmeshed capacitor plates
mean low capacity, high inductance, and
usually poorer reception.
The Gang's All Here. Radiomakers in
the 1920s fought these problems by piling
tuning circuits into the "tuned- radio -frequency" receiver. Old radio catalogs advertised the "4 -gang TRF" that boasted of
reception without man -made interference
(meaning other stations on nearby frequencies) . The set had a line -up of four radio-.
frequency amplifiers simultaneously tuned
by a 4 -gang variable capacitor. Adding more
-
-or
Fig.
1.
Nobody notices the odd spacing of the
typical low -cost superhet until they try to locate
a station at the high end of the dial. Blame this
on the
capacitor's tuning rate, not the superhef.
tuned circuits could certainly improve selectivity and gain, but another obstacle stood
in the way. It's the third major problem of
tuned circuits, which is operation at high
frequency.
Broadcasters and communicators were
reaching for ever-higher frequencies where
tuned circuits alone couldn't provide adequate selectivity to pick apart two close spaced signals, It's an electronic fact that as
frequency rises, the response of a tuning circuit retains the same proportions, or response curve, but appears relatively wider
to a signal of fixed width. This is illustrated
in Fig. 4. A voice signal 8 -kHz wide is
easily selected by the tuning circuit at a low
frequency, while the same signal wallows in
Fig. 2. Tuning circuit consists of variable capacitor
(under thumb) and antenna coil (under finger).
Tuning is lousy at high end of the dial.
the wider gap of the higher tuning circuit.
Everything about the two circuits is the
same -efficiency and LC ratio -only tuning
frequency is different. Yet the higher-frequency circuit allows a garble of signals to
enter the receiver.
Job for Super -Man. Then came the
concept that touched off the revolution. If
higher frequencies and variable tuning cause
trouble, why not get rid of them? That's the
secret of the superheterodyne. First, incoming antenna signals are juggled downward
in frequency. Then, tuning circuits can
operate on them with high selectivity and
sensitivity. As we'll see, the superhet's amplifiers will be mainly fixed- tuned, so energyrobbing tuning ratios can be avoided. To see
how the idea operates, first pick apart the
word itself.
The prefix "super" is short for "super-
72
ELEMENTARY F+LSCTSoNICI{
www.americanradiohistory.com
Scope photos show effect of introducing resistance in a tune:: circuit. Curve at left
shows good selectivity. Note how narrow the "spike" is at tcp. Fig. 3B (right)
shows same circuit setup except that resistance added to circuit broadens curve.
(Fig. 3A)
TUNING CURVE
DESIRED SIGNAL
DESIRED SIGNAL
r_
UNDESIRED
SIGNAL
REJECTED
D SIGNAL
iI
I
(
1
I
1
.9
MHz
1.0
LOW
1.1
90
100
HIGH
BAND
110
MHz
BAND
Fig. 4. Low- and high -band response curves have
same shape. Selectivity, though, is poorer on
high band because signals appear closer together.
emerge the three most important frequencies
(Fig. 5) for comprehending the superhet:
RF or Radio Frequency. This is the
original signal from the station. It's picked
out of the air by the antenna, and selected
by the first receiver stage. But it won't remain a high frequency for long.
IF. This is the "supersonic" signal. Since
the term supersonic is too aeronautic, not
sufficiently electronic, it's referred to as the
sonic." It refers to a new signal born within
the superhet. It's dubbed supersonic because
it's lower in frequency than a radio signal,
but higher than an audio frequency.
"Heterodyne" literally means "different
Fig. 5. Three major frequencies found in superhet:
A) the radio frequency picked up by antenna,
shown here without modulation; B) local oscillator
signal higher in frequency than input RF signal;
C) IF signal which is the result of subtracting RF
signal from local oscillator output.
forces." In the superhet it refers to a technique that mixes two different frequencies
to generate a third one. From this brew will
NOVEMBER -DECEMBER,
1969
www.americanradiohistory.com
.917p7{.,p
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SUPER SUPERHET
"intermediate frequency," or simply IF. This
is the desirable low frequency that all RF
signals must become.
Local Oscillator. This is the circuit that
creates the third essential superhet signal, the
local oscillator frequency. It's a generator
within the receiver to produce a steady (unmodulated) signal.
With these three signals, we can restate
the main idea behind a superhet: The incoming RF signal is mixed (heterodyned)
with the local oscillator frequency to produce
the IF signal on some lower (supersonic)
value.
There's a musical analogy for the process:
Strike adjacent notes on a piano and there's
a "sour" sound. It's because the original
tones mix and produce a third one, or "beat"
tone that imparts the dissonant sound. The
beat note occurs as a difference frequency
between the two original notes. In the super het, the RF signal is equivalent to one piano
note, the Local Oscillator equivalent to the
adjacent note. The IF signal is the beat note
produced by mixing the original tones.
Enter RF. To start the process, examine
the front end of the superhet shown in Fig. 6.
We'll assume the radio is tuned to a broadcast station in the lower end of the band, at
710 kHz. In a typical table radio, the incoming RF signal is tuned by a variable
capacitor and loopstick (or some other type
of antenna coil) . The signal is applied to the
Mixer stage where the heterodyning process
takes place. (Some people call this stage the
IF FREI.
455 kHz
GANGED TUNING
OSCILLATOR TUNE
Fig. 6. Here's the block diagram for the front end
of a superhet receiver. Dotted line for ganged
tuning means both variables are on the same shaft.
irsk=tS;,
,.d<£-
i
"Converter" or the "First Detector. ") Whatever the name, the stage combines the
710 kHz station with a steady signal from
the Local Oscillator. That oscillator signal
is on 1165 kHz. Why the odd number?
Recall that the goal of the superhet is to
convert the high RF signal to a low IF which
is on a fixed frequency. The value will be
455 kHz, a standard IF frequency for home
AM radio. Thus, a 710 kHz signal mixed
with an oscillator signal of 1165 kHz produces the 455 kHz difference frequency.
This is the result of a mixing or heterodyning
action.
Tricky Tracking. Now tune the radio to
1560 kHz on the BC band. Somehow the
Local Oscillator must rise to the occasion
and produce 2015 kHz. Simply subtract
1560 (RF) from 2015 (Oscillator) and
Fig. 7. Author points out the local oscillator tunable capacitor. Smaller number of plates is the
tipoff. Larger capacitor tunes in radio signal.
there's 455 again (the IF). How the Local
Oscillator adjusts to each signal is done by
tracking. The variable capacitor -the one
that is manually tuned -is a two -section unit
with two sets of plates on one shaft. (See
Fig. 7.) One section tunes the RF signal in
the antenna circuit as the other simultaneously tunes the Local Oscillator.
It's akin to two runners trying to maintain
a given separation. If the leader speeds up,
the follower adjusts his pace to keep a constant distance. In a receiver, the local oscillator tracks the air signal to maintain a
455-kHz span. You can recognize these
multiple, or gang- tuned, circuits in a schematic diagram by the dotted line between
circuits, as shown in Fig. 6. As the larger
section selects stations from 550 to 1700
kHz, the other section produces oscillator
signals from 1005 to 2155 kHz- always
74
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
,-4;:
..
PENTAORID
CONVERTER
TYPE 12BE6
IF AMPLIFIER
TYPE ISBAS
T2
POWER
DIODE DETECTOR,AVC,
AUDIO AMPLIFIER
TYPE 12AV6
T3
AMPLIFIER
0.002 TYPE 5005
1
TS
400 V
12
0.02
100 V
1200
0.47
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50
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RECTIFIER
TYPE 35W4
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400 V
Na 40 OR 47
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LINE
NOTE
TYPE
TYPE
12AV6
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5005
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ce"
Fig. 8. Here it is! Probably the worlds most produced circuit is the 5 -tube
superhet schematic diagram shown here. It has remained unchanged for decades.
Transformers T2 and T3 are 455 -kHz IF units often called IF tins."
455 kHz above the RF value.
The Super's Heart. If the Mixer is the
mathematical brains of the superhet, the IF
Amplifier is its heart. For it is here that most
of the receiver's extraordinary sensitivity and
selectivity are created. Although an IF amplifier may consist of one to four stages, the
basic benefit is the same. It is fixed -tuned
to a single frequency (the IF) so there's
no problem with unfavorable tuning ratios as
in the old TRF circuit. And it operates at
relatively low frequency where selectivity is
good and amplification can be more efficient.
A single -stage IF amplifier can be seen in
Fig. 8.
In fact, it's possible to have too much of a
good thing. The IF amplifier in a table radio,
for example, is aligned by adjusting its tuned
transformers to 455 kHz (Fig. 9). Unless
the manufacturer used care in his design, the
high sensitivity of an IF stage may trigger it
into oscillation to the accompaniment of
shrieks and howls. In an FM receiver, precise alignment may produce such sharp IF
selectivity that quality suffers because of
"side -band cutting "
part of the signal
fails to squeak through. In a TV set, IF
alignment is extremely critical to preserve a
balance between low and high frequencies
which create large and small detail in the
the stages are conventional and there's much
more to be said about the superhet's special
circuitry. The second detector (the mixer is
the first detector) is merely a rectifier that
slices away the upper or lower half of the
IF signal voltage (either positive or negative
portion) as the first step in the detection
process. (Otherwise positive and negative
halves of the IF signal would cancel each
other later on.) The output of the detector
is the desired audio frequency, which is
boosted in the audio amplifier and finally
reproduced in the speaker.
Killing the Image. The superhet is the
reigning monarch among receivers, but it
-a
picture.
Second Detector and Audio. To complete the superhet, we need only add a second detector and audio stages, as shown in
Fig. 8. We won't go into detail here because
Fig. 9. Author points out IF tins -These IF coil
units received their name from the galvanized-iron
shield used years ago. Today, aluminum is used.
NOVEMBER- DECEMBER, 1969
75
www.americanradiohistory.com
[email protected] SUPER
SUPERHET
:z
DESIRED SIGNAL
100 kHz
--4._z_
also suffers from certain electronic faults.
A major one is images, ghostly interference
which springs from a superhet's basic operation. We've seen that an IF amplifier is
poised, ready to grab and amplify any signal
on 455 kHz. The problem is that for any
given setting of the tuning dial there are two
possibilities for creating 455 kHz.
For example, if the set is tuned to 1600
kHz, the Local Oscillator will match it with
2055 kHz, so the 455 -kHz difference is produced. But a dangerous possibility exists if
there's also a station on 2510 kHz in the
vicinity. Like the desired signal it can mix
with the oscillator to produce 455 kHz
(2510 2055 = 455). And it can happen
even though the antenna-tuning circuit is actually tuned to 1600 and is expected to reject
the interfering signal (see Fig. 10). There's
so much gain in the IF amplifier, plus poor
selectivity in the RF tuning circuit, that
"images" often bull their way past the receiver front end and into the IF strip. These
are the mysterious police or aircraft stations
heard in FM radios, or teletype and other
out-of -band signals in CB and ham sets.
There's a cure for images, but it's neither
simple nor cheap. One technique is to raise
the IF frequency from, say 455 to 1600 kHz.
The idea is that the higher the IF value, the
more distant in frequency a signal must be
to create an image. This removes the objectionable signal so far from the band of
operation that even poor selectivity of an RF
tuning circuit is able to reject it. There is,
however, a limit. As you'll recall, selectivity
of an IF amplifier is good because of low
operating frequency. An attempt, therefore,
to remove the image by raising the IF frequency can become self- defeating. Good
receivers, though, capture the benefits of
both high and low IF frequencies.
Takes Two to Tango. The dual conversion circuit, found in much CB, ham and
communications equipment contains two IF
amplifiers. One is tuned to a high IF frequency to obtain the benefits of good image
rejection. The second amplifier is at a low
frequency to net high selectivity. An example
of how the system operates is shown in
Fig. 11. Note that a second local oscillator
is required for the two-step conversion.
RF Amplifiers. Now return to the front
IMAGE SIGNAL
2510
--
455 kHz
DESIRED
SIGNAL
455 kHz
IMAGE SIGNAL
/v
2055 kHz
Fig. 10. The problem with superhet circuits is
images. Two different frequency signals may mix
and create 455 -kHz IF signals that interfere.
1ST IF
2 MHz
-
Fig. 11. Dua -conversion superhet operates by two stepping down to the low IF-27 MHz to 2 MHz and
then from 2 MHz to 262 kHz. Used a lot in CB rigs.
end of the receiver to examine another
image -killer. It's the RF Amplifier. The stage
places more tuned circuits before the mixer
so an image signal out of the band is less
likely to get through. Another benefit is that
the RF stage also boosts the superhet's sensitivity, or ability to amplify weak signals.
The table radio of the last few decades, however, has rarely included an RF stage. Local
AM stations are usually strong enough to
drive the mixer directly and the additional
components are hardly worth the added expense in very low -cost receivers.
An RF amplifier, however, is almost always found in the car radio, FM tuner and
TV set. An important reason is that as RF
frequency rises much above 15 MHz, atmospheric noise decreases and internal circuit
noise becomes increasingly a problem. This
is `minimized by adding a well-designed RF
amplifier. It can produce less internal noise
than a mixer stage. And it's mostly in the
first stage where a receiver's "signal -tonoise" ratio is determined. Tune a cheap
short -wave receiver, with no RF stage, and
you'll probably hear the speaker grow quiet
on higher bands, a giveaway sign of poor
sensitivity.
There's a similar reason for an RF amplifier appearing in virtually every car radio.
It's because mobile operation imposes a spe-
76
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
efi
IF AMPLIFIERS
9NVERTER
LIA
TYPE
2N1526
TYPE
TYPE
T2 2NI524
T;
T3 2N1524
Ti
19
14
Fig. 12. It figures that the
transistor would make it big
with the superhet circuit.
Some circuit design had to
come about fo reduce costs.
The first stage, "converter,"
combines the functions of
mixer and local oscillator.
18
at 10.7 MHz. It pushes images that far from the desired
frequency. In television, the
RI?
SECOND
standard IF frequency is apDETECTOR
II
TYPE
proximately 41 MHz.
C3
1N295
All- American Five. Duru
ing 1968, about 40 million
RI5
POWER
AUDIO
radio sets were sold in the
DRIVER
AMPLIFIER
U.S.A. And chances are that
circuitry in these radios will
TYPE
262614
6
be virtually the same as in
Ts
o
SP
Fig. 8 if it's a tube model; or
R4;
similar to Fig. 12 for transisCI6
torized models. These diaR10
grams are representative of
C13T "lI
the most popular superhets
now in use.
The tube model is somecial stress on reception. A car is often driven times called the "All- American Five," which
between cities where borderline signal refers to a 5 -tube line -up found in zillions
strength is encountered. Every bit of sen- of AC /DC table radios. That title is being
sitivity is needed under mobile conditions. taken over by the 5- transistor equivalent.
Which IF? The standard automobile ra- What's next? Probably the All-American
dio has an IF frequency of 262 kHz instead IC- assuming that the integrated circuit
of the standard 455 for home sets because isn't made in Japan.
An All- American Onel Although most
listening is often done between cities. In a
given city, the FCC assigns AM stations a commercial superhets have about five stages,
minimum spacing on the dial of 20 kHz. An there's an ingenious circuit which uses just
ordinary table radio has little trouble sepa- one tube! Its secret lies in a compactron tube
rating such stations. But if you drive between which combines three amplifiers in a single
cities, you could pick up two AM stations glass envelope. It makes possible a one -tube
from different cities with only 10 kHz circuit that fulfills all requirements of a true
spacing. Now the set requires additional superhet. You can easily build and align it
selectivity to pull them apart. This is done for the standard broadcast band, as we'll see
by the choice of a lower 262 kHz IF. You in a moment. This is a homebrew project
could object and say that a lower IF value you can thrust under the nose of some electronic egghead and çhallenge him with:
aggravates the image problem. It would
it weren't for the use of an RF amplifier in "Quick, name the circuit!" When he says
car radios. It improves selectivity and helps TRF or regenerative, you snicker back,
"Superhet." You can prove it by tracing out
cut the images.
There are several other IF frequencies the diagram (in Fig. 13) this way:
Broadcast signals in your
RF Tuning.
now in use, mainly depending on the band
of operation. A low value of 455 kHz is area enter the antenna. The one you want
not practical for the FM broadcast band (88 to hear is selected by the tuning circuit of
to 108 MHz). It would make the receiver coil Ll and variable capacitor C3A. But we
extremely susceptible to images since image need better selectivity than is possible in an
frequencies could exist directly within, or RF tuning circuit.
Local Oscillator. This is a job for a low
near, the FM band. Effective rejection would
Part of tube VIA functions as a local
IF
frequency
is
IF.
So
the
impossible.
be nearly
14
I
-if
77
NOVEMBER-DECEMBER, 1969
www.americanradiohistory.com
:
EI:f.,Ma1F
t.44,.11**
(g/0
ly tuned to 455 kHz and thus accepts only
that frequency from the mixer plate (11). All
else is sliced away and the IF frequency is
amplified by triode V1B. The output of the
SUPER SUPERHET
oscillator to heterodyne the incoming RF
signal to 455 kHz. The oscillator is formed
by a tapped coil and variable capacitor (L2C3B). These components help drive the tube
into oscillation; cathode (pin 10), grid
(pin 2) and oscillator plate (pin 3). Notice
that tuning capacitor C3 is a 2-section variable with a dotted line to show ganging.
When the RF section is tuned, oscillator frequency also changes, and maintains its generated signal exactly 455 kHz above the incoming station.
IF amplifier in most commercial circuits is
another IF transformer for additional selectivity. But this is a simple circuit for the
experimenter so an untuned choke coil
(L3) appears instead.
Detect and Listen. The 455 -kHz signal
detected into audio by diode D1 and
fed to the remaining triode amplifier (V1C)
and to the loudspeaker for listening. Sorry,
no AVC circuitry.
Now that you can prove that a superhet
can be a one -tube wonder, how about trying
your hand at building it? It may not blast
is now
Y111111111111111111111111111111111111111111111111111wuw1111111111:11111111u1111111111u1111w.:11
TANT
Q
=
J1
n
=
C1
=
tio
C2
L1J
47pF
NC
9 0p
O
C3A
°op
T2
T1
455kHz
47pF
C5
'1)
Ó1
SPKR
=
O
R2
470K
ypF
R6
C10
25pF
10v
R7
)
C11A
TRIMMERS
+
30pF
1K
0116
30VF
1500
150V
60íT051 VIEW
Fig. 13. You can build your very own superhet receiver using only one vacuum tube, the
well -known 61(11 compactron tube. Look hard and you will be able to find almost all the
functions of the superhet in the above circuit as you would in the famous all- American
Eve circuit. But don't rush into the construction until the next issue is published.
Then we will give you complete details, photos, diagrams, and parts list.
Mixer. Combining RF and local oscillator signals also occurs in tube V1A. As the
electron stream from the cathode is varied
by both oscillator and antenna signals at the
grid (2), a resulting mixture appears at the
plate (11) . Several possible combinations
exist at the plate -as various signals add
and subtract. But only the 455 kHz difference frequency is extracted. The reason is
the..:
IF
Amplifier. Transformer Tl
is sharp-
forth on weak AM signals, but it performs
respectably well on local stations. Selectivity
is about as good as that of an ordinary table
radio. The project is ideal for an experimenter trying to squeeze the most performance out of the fewest parts. Need more help
than offered by the schematic diagram? Then
wait until the next issue of ELEMENTARY
ELECTRONICS for the complete construction
details. In the meantime be sure you understand all there is to know about superhets.
18
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
Spacecraft
flights
to other planets
require the
services of
by Wes Robinson
imagine sterilizing a bullet in a laboratory,
loading it into a germ-free rifle breech,
firing the rifle and hitting the target with a
lead slug still as clean as the moment it came
out of the laboratory.
A comparable feat of far greater magnitude faces space scientists who are planning
to send unmanned spacecraft to other planets. By international agreement, the United
States has committed itself to land only
sterile probes on the soil of neighboring
planets. A craft landing on Mars, for example, must be 99.9999 per cent clean. The
reason: man doesn't want to reach the surface of a distant planet only to rediscover
transplanted biology from his own planet.
Bugacide. The killing of microorganisms
on a spacecraft can be almost as much a
matter of bookkeeping as it is microbe war -,
fare. Contamination samples are taken from
THE
BUG
KILLERS
first stages of spacecraft assembly
through to the completed vehicle. Results
of the "bug- count" sampling are fed into a
computer, which keeps records of the microbial buildup. As the spacecraft becomes
more complex, organisms begin to be added
between attached surfaces, and bug counts
must be taken with greater. frequency. The
sterilization heat cycle for a particular
planetary landing vehicle will be based on
the computer -calculated germ load for that
the
vehicle.
Counting the number of microorganisms
on a spacecraft bound for another planet is
tough enough, but biologists also must predict all possible events which might affect
the lander's sterility on its outward journey.
Each potential event, such as a meteorite
striking the vehicle and dislodging some
bugs still alive but trapped within the struc-
Facts and Photos courtesy of Boeing Magazine
NOVEMBER -DECEMBER, 1969
81
www.americanradiohistory.com
These and other problems have led engineers to ask the advice of biologists, metallurgists, manufacturing specialists and research scientists before they put even preliminary designs on paper.
Born to Die. At Boeing,
the task of spacecraft sterilization begins in the laboratory. Here, Dr. Richard 01son and a small staff of assistants grow "bugs " -batches
of microorganisms -and then
think of ways to get rid of
them. In the search for methods of sterilization, the microbes are baked, smashed,
irradiated and subjected to
rarified atmospheres. The results of this mayhem are cataMicroorganisms are treated with loving care provided they can surlogued and routed to others
vive being shot from guns like cereals. Bugs shown above made it.
studying planetary quarantine.
Dr. Olson's group is conture, is assigned a "probability number" centrating on killing one strain of germs in
based on analysis and research. A computer particular, a tough little bug of the aerobic
then adds up all these probabilities, and (oxygen -liking) spore-forming classification
comes out with an overall probability figure called Bacillus subtilis. From an aerospace
for contaminating a particular planet with biologist's point of view, spore- forming ora particular spacecraft at a particular time.
ganisms are troublesome. The spores resist
Heat Wave. Sterilization is an absolute
the sterilizing effects of dry heat and prove to
term-either you have it or you haven't. be much tougher to kill than normal cells.
To achieve it requires that a spacecraft liter- Dr. Olson believes that if these aerobic spores
ally be baked at 257 degrees Fahrenheit. This can be eliminated, all other organisms autorequirement has caused problems.
matically will be destroyed in the process.
No large interplanetary vehicle ever has
Boeing's sterilization research work is dibeen oven-baked completely, although small rectly applicable to the proposed Viking
vehicles and parts of larger spacecraft have. project, a NASA assignment to land an unCertain spacecraft materials tend to resist manned probe on the surface of Mars in
heat and, in so doing, may protect "bugs" 1973. A team composed of researchers and
that have lodged under the surfaces of those designers from Boeing, General Electric and
materials. Some strains of microorganisms Hughes Aircraft is hoping to win the Viking
are tough to kill with heat. Heat can make bid over teams headed by McDonell Dougsome spacecraft materials brittle.
las and Martin Marietta. Although GE's
primary concern will be with
the spacecraft's entry into
the Martian atmosphere, the
company's sterilization experience on the now -canceled
Voyager program also will
prove valuable.
They're Everywhere. Experiments also have helped
describe and suggest solutions
to the sterilization problem.
Boeing researchers, for example, found that micro-organisms buried within a solid
propellant fuel might survive
some rocket firings. How Thousands upon thousands of microorganisms are grown in the
(Continued on page 99)
laboratory, cataloged in canisters and marked for extinction.
THE BUG KILLERS
ELEMENTARY ELECTRONICS
82
www.americanradiohistory.com
BEGINNER'S
CPO
Learn as you build with
oscillators are all about
circuit that'll clue you in on what
/ by Wayne Kiser, WA9VKP
a
Getting started in electronics is almost
always an exciting experience -almost, we
say, because that first step can be so complicated that the poor beginner becomes
confused and discouraged.
Here's a simple project that will make
that first step easy for you or someone you
may teach. Schematic symbols are the language of this new adventure. But how hard
it is for the newcomer to relate symbols to
the parts they represent! Reason is that parts
placed on a chassis or on a printed circuit
board don't look much like the neat drawings in a book. Even so, a simple schematic
like that of an audio oscillator can help
form the mental links necessary.
Tail Chasing. What's an oscillator? An
oscillator can result when part of the output
voltage is fed back into the input of practically any amplifier. The same effect results
when a dog chases his tail. He goes round
and round but doesn't get anywhere. In the
case of the oscillating circuit, however, this
changing voltage can be fed into a speaker,
causing sound. The circuit we show here is
that of a typical audio oscillator. And to
understand it better, we suggest you draw
the schematic on a board (see Parts List)
right now, studying the symbols and the
hookup of the circuit as you do so.
Here's how it works: when the key is
closed, current flowing through the 12,000 ohm resistor (R1) into the base -emitter junction of the npn transistor (Q1) causes a
11
7
Schematic for Beginner's CPO. It's best to
buy parts first, arrange them as per schematic,
then draw schematic on wood block.
B1
PARTS LIST FOR BEGINNER'S CPO
battery IEveready 1015
Q1
-2N170
-1.5 -volt penlight
or equiv./
C1- 0.1 -uF capacitor
411-
SPKR
L
transistor
Q2 -2N107 transistor
R1- 12,000 -ohm, 1/2 -watt resistor
R2- 100 -ohm, 1/2-watt resistor
3/4 -in. wooden block
1 -51/2 x 51/2 x
Fahnestock clips
Telegraph key
Miniature PM speaker
Misc.-Wire, solder, staples, battery holder, etc.
J
w,.
IIIIIIIIMHWRII.
83
NOVEMBER -DECEMBER, 1969
www.americanradiohistory.com
BEGINNER'S CPO
collector-emitter current to flow. But since
the collector current of Q1 must flow
through the base-emitter junction of the pnp
transistor (Q2), Q2 is similarly turned on
and its collector-emitter current flows
through the speaker voice coil.
When current begins to flow through the
speaker, a voltage is developed across it.
Result is that the terminal connected to the
collector of Q2 becomes more positive than
the terminal connected to the key. This
positive voltage is coupled through the 100 ohm resistor (R2) and
the 0.1 -uF capacitor
(C1) back to the base
of Ql, causing additional base -emitter current
to flow in both transistors. This is the tail
chasing, because additional collector current
flows, and this in turn causes additional voltage to he developed across the speaker.
Repeat Performance. This cumulative
action continues until the capacitor is fully
charged. At this point, the like charges on
both sides of the capacitor begin to repel
and the voltage at Q l's base becomes more
negative. This decreases current flow in the
collector of the npn transistor (Q1), and
this in turn causes the collector current of
the other transistor to decrease as well.
Eventually, the voltage across the speaker
reaches zero. When this happens, current
again flows through R1 into the base -emitter
junction of Q 1 and the cycle begins all over
again.
Completed CPO, with speaker connected, but less key. Staples hold
most parts in place; Fahnestock clips
and battery holder are nailed to board.
Parts replace symbols in this schematic.
Study the appearance and construction of
the few parts used. By now you should know
what each part is and how it works. When
explaining the workings of components to
other people who haven't much previous
knowledge, though, be extra careful not to
give too much information at one time.
The final step is to place the parts on the
schematic you drew earlier and solder the
connections. The wires can then be stapled
directly to the wooden block.
Connect the speaker and the key, and the
oscillator is ready for work. The completed
project can be useful in learning the code,
or, through use of transistor sockets instead
of direct connections, for testing which
transistors are npn's and which are pnp's.
Hot News For
Your New Flame
A new ultraviolet fire detector that reacts to
the first trace of flame, then flashes an immediate alarm has been developed by Honeywell's
Apparatus Controls Division. Because this new
detector is sensitive only to ultraviolet radiation,
it responds only to an actual flame or explosion.
It can't be fooled by heat or infrared radiation
or even sunlight. In fact, it can stare at the sun
all day without giving an alarm, since it actually
has trouble telling day from night.
84
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
all NEW
BASIC COURSE in
ELECTRICITY &
ELECTRONICS.
PART
1
UNDERSTANDING
DC SERIES CIRCUITS
HAT YOU WILL LEARN.
This
part one of a brand new
W iscontinuing
series and contains a thorough description of
the series circuit and its basic
connections. It also explains how
total', resistance, total current,
and voltage drops are determined in such a circuit. You will
learn how to reduce a voltage to
a desired level by the use of a
dropping resistor, identify series connections in complex electronic circuits, and determine
total resistance and total current
in a series circuit. (Turn page)
* This series is based on Basic Electric i '" ctronics, Vol. 1, published by Howard W. Sams & Co., Inc.
85
NOVEMBER -DECEMBER, 1969
www.americanradiohistory.com
[email protected]®
r
Basic Course
o
v
V
WHAT
IS
A
SERIES CIRCUIT?
A series circuit is an electrical circuit in which all the components are connected end to end.
Voltage and Current
I----1v
o-
-1
a-
a
o-- o--o-- o---
a-
o - o--
CD-
ONE UNIT LENGTH
+
TWO UNIT LENGTHS
Do you recall the voltage distribution which occurs across a resistance? If
one volt is applied across one unit length of wire, for example, what will happen
to the voltage distribution across the same size wire that is twice as long? One half volt will appear across each unit length. One -half the total voltage will
be dropped across each of the two units. Since the resistance is doubled, the
current will be one -half as much.
o
VOLTAGE DISTRIBUTION
Voltage will be distributed across the unit length of resistance in the manner
shown in the diagram. Doubling the voltage will cause twice the current to
Current Depends on Voltage
1V
o----
o-
2V
o---
o--
_
0o--H--1V
ONE UNIT LENGTH
o- o-
0--
o-
o---
I
1V
+
o--
---I
ONE UNIT LENGTH
flow through the resistance. One volt is distributed (dropped) across each
half of the resistance, increasing the current that flows through its section.
An example of a series circuit is the manner in which the vacuum -tube
filaments of some radio and television sets are connected. As you can see in
the following diagram, each filament requires 12 volts and a current of 0.15
ampere. This identifies another characteristic of a series circuit
components in a series circuit have the same current flowing through them.
Another application of the series circuit is the economical series -string
Christmas -tree lamps. The number of lamps needed in a string or the amount
-all
ELEMENTARY ELECTRONICS
86
www.americanradiohistory.com
Vacuum -Tube Filaments in Series
(s\
_
+
(\
12V
12V
12V
1V
12V
"+
129V
+(\
+(.\
f
12V
12V
12V
12V
12V
FILAMENTS = 80n EACH
drop reof voltage to apply can be determined by Ohm's law. If the voltage
120 -volt
a
to
connected
be
is
to
string
the
and
volts
15
quired by each lamp is
in
series.
are
required
lamps
outlet, then eight
Symbol Designations
voltage
Care must be used when referring to voltage in a series circuit. A
the IR
from
value
drop across one resistance among many may be a different
be
identified
should
for
example,
drop across the others. A voltage across Ri,
E total).
as that voltage. The source voltage should be designated, as ET (for
a series
of
parts
all
in
same
is
the
current
Since
RT.
Total resistance becomes
I.
as
circuit, it remains
Identify All Parts of
Circuit
R5
R6
1
a
I=
E1
Et
P;
Rr
+
__2
Ì
Er = El + E2
T
WW,
1/\MM,
R1
R2
Total Resistance in the Series Circuit
Current in a series circuit is determined by the values of total resistance
and total voltage. The total source voltage is distributed proportionally across
each of the series resistances, depending on their 'ratios to the total resistance.
Total resistance in a series circuit is the sum of the resistances between the
terminals of the source. That is, RT will equal R1
+ R2 + R3 + etc.
Total Resistance
P1
R3
R1
Rt =
R1
P2
+ R2 + R3
The lamp shown above does have a resistance, even though it is not a resistor. Therefore it is marked as R2 for calculation purposes.
NOVEMBER -DECEMBER,
87
1969
www.americanradiohistory.com
Basic Course
Ql. Can the circuit on the opposite page he called a series
circuit?
Q2. The symbol for total voltage is
Q3. If R1 is 4.5 ohms, R2 is 6 ohms, and R3 is 6 ohms in the
diagram above, what is RT?
Your Answers Should Be:
Al.
Yes. All elements are connected end to end.
A2. The symbol for total voltage is ET.
A3. RT = 16.5 ohms. (The total resistance in a series circuit is the
sum of all the resistance values across the source.)
Total Voltage in a Series Circuit
In addition to determining the total resistance of a series circuit, the total
voltage must be calculated if there are two or more voltage sources in series.
Total voltage is found in the same manner as the total resistance; that is, the
sum of the individual voltages equals the total voltage.
Total Voltage
3V
3V
1I11+
II
o
--,Ill+
3V
Er-E1+E2+E3-9V
C
There is a separate problem in the calculation of total voltage, however.
Some of the voltage sources may Le in opposition to others, in which case the
total voltage will not be the simple numerical sum of all the voltages. If the
polarities of all the voltage sources are in the same direction, the voltage values
are added together. If the polarities are in opposite directions, the values are
subtracted, and the polarity of ET is that of the larger voltage source.
¡
Simplifying
a
Series Circuit
R1
1
i
E1
E2
+ll1-
+I
R3
o
E3
ET =
El +
E2 + E3
Rr=R1+R2+R3
88
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
11
iyC
..,
circuit with more than one source and more than one load can be
redrawn to show a circuit with only one source and one load.
A series
Q4. How must you treat the following series circuit to find
the total source voltage?
oilII
-El
+
liii
.3V
10V
7V
14V
26V
-,or
+
-o
E5
E4
E3
E2
IINN+
--
Q5. What is ET for the circuit below?
Q6. What is RT for the circuit below?
Q7. What is IT for the circuit below?
El
,DI+
i
R3
R2
B
111
24V
7V
A
RI
N
+
+1111
3V
13V
E4
E3
E2
Il'+
R
MM
2n
1n
Q8. In which direction will current flow in the circuit above?
Q9. Could the total resistance be represented by a single
resistor?
Q10. What is the total resistance in each circuit (a, b, and c )
below ?
A
vr
h
R2
R1
4a
On
E1
6V
6V-
R3
T
I
R2
R1
1
+
E2_
El
16e
4n
B
E2
1111
30V
ilii+
C
19V
15V
R2
R1
114e
6n
E3
+f1l1
`
15V
R4
R3
18e
31e
E2
9-
f
l+
R5
E3
9V-TT
Q11. What is the total voltage in each circuit?
Q12. Draw an equivalent circuit, containing only one source
and one load, for each of the circuits. Label the value
and polarity of the source and the value of the resistance.
Your Answers Should Be:
A4. You must first add all the voltages having a polarity in one
direction (negative to plus) . Then add all the other voltages
having a polarity in the other direction. Subtract the smaller
from the larger. This will determine the amount of the overall voltage (ET) and its polarity.
(Continued on next page)
NOVEMBER -DECEMBER,
89
1969
www.americanradiohistory.com
Basic Course
o
(Continued from previous page)
..E1
E2
26V
FIRST:
-
E4
o
14V
10V
Er _ El +E2 + E4
= 26
7V
3V
40V
SECOND:
Er
+14 +10
= E3
FINO:
+ E5
Er = 50V
= 7V + 3V
= 50V
-
10V
= 40V
= 10V
-
A5. ET = 24 + 7 13 3. That is, 31- 16 =15. Therefore, ET15 volts, negative to positive left to right.
A6. RT= R1 +R2+R3 +R4.RT =15 ohms.
A7. IT = ET /RT. IT -.15/15, or 1 amp.
A8. The current will flow away from the negative terminal and
into the positive terminal of ET.
O. Yes. Once the total resistance has been found, it may be represented by a single resistor.
A10. (a) 104 ohms
(b) 120 ohms
(c) 100 ohms
111. (a) 12 volts
(b) 60 volts
(c) 109 volts
Al2. A
o
B
1E r
RI
T.
1040
60V
RT
120a
C
R1
100a
Examples of devices having several voltage sources in series are flashlights
transistor radios, battery sleeve or tube, and automobile batteries. (See
diagram top of next page.)
Current in a Series Circuit
1f a series circuit has an RT of 170 ohms and an ET of 34 volts, what is the
current in the circuit? The current will be equal to ET /RT or 0.2 ampere
(34/170). If a series circuit has three sources (all aiding one another) and
two resistances, current can be determined by:
1T_
E2
o
E3
RI+R2
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ELEMENTARY ELECTRONICS
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Voltage Sources in Series
TRANSISTOR RADIO TV
1
I
I
I
BATTERY TUBE
6V = 3 CELLS /BATTERY
AUTO BATTERY
FLASHLIGHT
Voltage Drop in
a Series
Circuit
in the
The voltage drop across each resistance in a series circuit is found
the
and
value
resistance
if
the
a
resistor
same manner as the voltage across
is
expression
law
Ohm's
The
known.
are
resistor
the
current flowing through
by
current
E = IR. Voltage across a resistance is determined by multiplying
resistance.
circuit. After
The current is the same through each resistance in a series
drop across
voltage
the
determine
to
is
used
finding the current, the value of 1
each resistance in the circuit.
Q13. What is the total voltage of a source having eight 1.5 -volt
flashlight cells connected in series?
Q14. What is the total voltage of a source having fifty-five 2volt lead -acid cells connected in series?
Your Answers Should Be:
A13. Eight 1.5 -volt dry cells connected in series will develop
12
volts.
A14. Fifty -five 2 -volt lead -acid cells connected in series will provide 110 volts.
Determining Voltage Drops
the total
The sum of the voltage drops in a series circuit is always equal to
applied voltage.
Voltage Drops Equal Applied Voltage
+
R2 = 15n
F
=
110V
Ir5AMPS
-
g1 = 7n
EA1
=5x7
EN2
= 5 x 15
= 75V
= 35V
WM,
91
NOVEMBER- DECEMBER, 1969
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I
aBasic Course
\11
o
In the previous circuit, 5 amps will cause a 35 -volt drop across
the 7 -ohm
resistor and a 75-volt drop across the 15 -ohm resistor. Eut + ER° = ET.
Polarity Across the Loads
Current leaves the negative terminal of a voltage source, flows through the
circuit, and returns to the positive terminal. This direction of current
flow
occurs because of the voltage polarity. One of the terminals of the source
is
negative (repels electrons) with respect to the other. The opposite terminal
is positive (attracts electrons). In the diagram, for example, P1 is
30 volts
negative with respect to P3.
Polarity Across Loads
-
1.
T
R2 = 45n
P3
22.5V
30Y
.:1
+
R1 =
P
15a
7.5V
P1
C
Voltage in a circuit exists only between two points -never at one point only.
Therefore, voltage is expressed as being across two points in a circuit, or in
terms of one point with respect or in reference to another point. The point at
which current enters a resistance is negative with respect to the point at which
it leaves.
A common ground is used as the reference point for expressing voltages
unless otherwise specified. If a ground symbol is shown (see the diagram
below), it becomes the common reference point for all voltage points in the
circuit.
o
ference Point
P1
R2
P2
-MA/A,
14n
16n
R1
R3
P3
P00
i
E1
1
50V
T
Current will flow from P1 to P2 to P3 through the source to ground and from
ground to P1. In this case, I is equal to 1 amp. This means P1 is +16 volts
with respect to ground. P2 is +14 volts with respect to P1 (thus 30 volts positive to ground). P3 to ground (in either direction) is +50 volts (the source
voltage or the drop across the three resistors).
o
Q15. What is the value of ET in the circuit below?
92
ELEMENTARY ELECTRONICS
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IT in the following circuit? Which way will current flow with respect to Pi and P2?
Q16. What is
R2
R3
R4
^MMt
'WAN
E31
eM/ñ//1
30V
.-
RI
1
4a
P2
Pl
Q17. What is the total resistance of the following circuit?
RI
R2
^WM
N\/Wÿ
57K
160K
+
R3
h
74V
33K
R4
i
100K
Q18. What is the voltage, with reference to ground, for all the
points (P) on the following diagram?
R2
R1
P3
520o
440a
P4
R3
65K
R4
40a
Your Answers Should Be:
A15. 15 volts.
A16. IT = ET/RT. ET = E3
-
(E1
E2) = 15V
R4 = 30 ohms
RT = 11
R2
R3
IT = 15V/30 = 0.5 amp
Since the 30 -volt source is larger than the
+
+
+
combined 15 volts
of the other two, the current will flow from P2 toward P1.
A17. RT = 370K.
That is, RT = R1 + R2 + R3 + R4 = 370K
ET
A18. IT = ITT
P2
P3
-
66V
66K
= 0.001 amp, or 1 ma
= +66V, P2 = +65.56V.
= +65.04V, P4 = +0.04V
Voltage Division in a Series Circuit
Voltage reference is one of the most important concepts to be learned in
electricity or electronics. An understanding of how much voltage exists between two points in a circuit often reveals the purpose of the circuit and how
it works.
As an example, a schematic of a vacuum -tube circuit is shown below. The
figure on the right shows a vacuum tube in series with a load resistance, R1.
93
NOVEMBER -DECEMBER, 1969
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10
Basic Course
f
o
The figure on the left shows how the tube can be considered as a variable
resistance. The output of this circuit is taken at a point between the tube and
the load resistance.
Voltage Reference
B+
P2
-
{i --- ;
+300V
10K
10K
P1
OUT
OUTPUT
VARIABLE
FROM
3K TO
17K
ELECTRONIC
GRID
CONTROL
J
CATHODE
r
In effect, the grid varies the resistance of the vacuum tube. P2 is always
+3O0V (to ground). P1 is a positive voltage (to ground) ; its value depends
on tube resistance at any particular instant. The tube resistance changes from
3,000 to 17,000 ohms. Since 300 volts is always across the tube and load resistance, the output voltage at P1 (with respect to ground) is large when tube
resistance is high and small when tube resistance is low.
o
VOLTAGE DIVIDER
Current is the same through all elements in a series circuit. In the circuit
on the opposite page the 300 volts can also be used for other purposes and in
other circuits. Yet, 300 volts is often too much voltage for some circuits. A
voltage divider is used to reduce the 300 volts to a level acceptable for use in a
lower -voltage circuit. To select the correct resistors for use in a voltage divider,
you must know how much voltage is required by the lower -voltage circuit. A
voltage divider, therefore, is a series of resistances whose values are such that
the desired output voltages are obtained at the various points with respect to the
voltage reference point. In some cases, a voltage dropping resistor is connected
in series with a load to obtain the desired voltage.
Voltage Dividers
+300V
1
-12V
R2
200K
R(DROP)
311
+110V
R(DROP)
P1
RI
LOAD
100K
OV
2A
B
10V
LOAD
C
50
MA
-
94
ELEMENTARY ELECTRONICS
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174 !.;
Q19. What is I in the voltage divider of part A above?
Q20. How much voltage is available at Pi in part A?
Q21. R (drop) in part B above is a(an)
Q22.
Q23.
Q24.
Q25.
resistor.
to ground.
Load voltage (part B) is
- - - ampere(s) flow through R (drop) in part B.
ohms.
R (drop), part C, is
watt(s).
The load in part C dissipates
Your Answers Should Be:
0.001 amp, or 1 nia.
100 volts. E = I X R1. 0.001 anip multiplied by 100,000 ohms.
R (drop) in part B is a voltage dropping resistor.
Load voltage (part B) is -6V to ground.
Two amps flow through R (drop) in part B. (Current is the
same throughout a series circuit.)
A24. R (drop), part C, is 2,000 (or, 2k) ohms.
If the voltage across the load is 10 volts, R (drop) must have
100 volts across it. 100 volts divided by 0.05 amp (circuit
current) is 2,000 ohms.
A25. The load in part C dissipates 0.5 watt.
A19.
A20.
A21.
A22.
A23.
P = IE. (Current through the load multiplied by the voltage
across the load.)
PRACTICAL APPLICATION OF THE SERIES CIRCUIT
In addition to hhat )ou have learned, there are mangy other applications for
a series circuit. They exist in almost every electrical device used.
Reducing Output Voltage of a Battery
A voltage -dropping resistance eau be used to lower the output of a 12 -volt
battery to operate a 6 -volt device (radio, meter, lamp, etc.). The dropping
resistor (when in series with the load) must have a value in ohms which will
Reducing Voltage with
+lIIl
a
Rheostat
T=?
u=?
12V
ADJUST
RHEOSTAT FOR
6V ACROSS
LOAD
4
RHEOSTAT
LI
12V RANGE
OR BETTER
permit the desired amount of current to flow through the device. It must also
have the proper wattage rating as determined by its current and voltage drop.
95
NOVEMBER- DECEMBER, 1969
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0
Basic Course
o
r
A rheostat (variable resistor) is quite often used as a dropping resistor in
this application.
The circuit on the previous page requires many careful adjustments and a
common -sense application of Ohm's law and power equations. Solutions to the
voltage- current -resistance problems are no more difficult than those you have
already solved.
Steps in the Adjustments of the Rheostat
1. Determine the approximate current the load will draw. The device should
be marked with its voltage and current requirements. The information can also
be found in the service manual for this particular component.
2. Be sure the multimeter is set on a voltage scale which will read the source
voltage (12 volts in this case) .
3. Adjust the rheostat for 6 volts across the load.
NOTE: The rheostat must be of high enough wattage to
carry the load current.
4.
5.
Be sure the device can be switched on and off.
Put a fuse in the device. The fuse should be capable of carrying the cur-
rent requirements of the load, while protecting it from an accidental overload.
o
Q26. If you do not know the current through the load and
the rheostat, and you do not have an ammeter which will
measure the current, how do you find the power required
for the rheostat?
Q27. How do you determine the size of the fuse?
Q28. Why should the multimeter be set to the range which can
read the voltage of the source?
Your Answers Should Be:
A26. You know the voltage drop across the rheostat, and you can
measure the resistance of the rheostat from the end of he
wiper contact.
Power =
E2
A27. The fuse must be able to carry the calculated current and
should be able to carry normal surges. Normal surges are determined by the characteristics of the device (load).
A28. The voltage range of the multimeter must always be set to
the scale that you know will not be exceeded. Voltage greater
than the range of the meter can cause excess current through
the meter and, therefore, cause possible damage.
96
o
ELEMENTARY ELECTRONICS
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Speed Control for an Electric Motor
Motors, such as the one used in an automobile for the defroster fan, are
sometimes connected to a switch having four positions (OFF -LO- MED -HI).
The low and medium positions are separated from the high position by fixed
resistors. Assume the motor turns at three speeds which require 3V at 1 amp
(LO), 4.5V at 1.5 amps (MED), and 6V at 2 amps HI). This cirçuit is shown
below.
Speed Control Circuit
OFF
%
HI
t
R1
02
20
ln
LO
1MEO
MOTOR
In the LO position the series resistance equals 3 ohms, which permits 1
ampere of current to flow. The 3 ohms is not the only resistance in the circuit.
The motor adds its resistance in series with the circuit. In the MED position
of the switch, the series resistance is 1 ohm. Again, the motor resistance is in
series with it.
Q29. What is the resistance of the motor when the switch is
in the LO position?
Rt
R2
2
i6Vb
L
Q30. What is the resistance of the motor when the switch is
in the HI position?
46V
HIi
Q31. What is the power requirement for each of the two resistors, R1 and R2?
Q32. What type of switch would be the one most likely used?
NOVEMBER-DECEMBER, 1969
97
www.americanradiohistory.com
o
Basic Course
Your Answers Should Be:
A29. The voltage applied to the motor in the LO position is
The current is 1 amp. Therefore:
R=
j
E
=
í
3
3V.
= ohms
A30. 3 ohms again. The full 6 volt is across the motor.
A31. It is determined by the largest amount of current which will
flow through the resistors.
PR2 = I112 XII ER2 = 1.5 X 1.5 = 2.25 watts
Pr = (ER1 T ER,) X IT. ER1 = RI X IT,
and ER2 = R2 X IT.
= 2V, ER2 = 1 X 1 = 1V.
PR1
1 amp X 2V = 2 watts, PR2 = 1 watt.
Therefore, R1 must have a power rating no smaller than
2 watts. The rating of R2 must be no smaller than 2.25 watts.
A32. The most probable selection for the switch would be a rotary
ER1
=
=
2 X 1
or wafer type.
o
WHAT YOU HAVE LEARNED
1. The basic electrical circuit is a series circuit.
2. A series circuit may have more than one source and load.
3. Current in
a series circuit is the same through all components.
4. Total resistance in a series circuit is computed by finding the sum of all
the resistances. That is, RT = RI + R2 + R3 plus whatever additional
resistors may be in series.
5. Total source voltage in a series circuit is the sum of the individual sources
6.
7.
8.
9.
10.
if their polarity direction is the same, or is the difference of the sums of
the opposing potentials. The larger will become ET and will control the
direction of current.
A series circuit may be represented with an equivalent circuit.
Total voltage drop in a series circuit is equal to the source voltage, or ET.
To describe a voltage at any given point you must identify its polarity
with respect to a reference point.
A voltage divider is a series circuit which employs a dropping resistor to
provide a desired voltage output.
When a dropping resistor is used to form a voltage divider, it must have
a safe power rating.
This series is based on material appearing in Vol. 2 of the 5- volume set,
BASIC ELECTRICITY /ELECTRONICS, published by Howard W. Sams & Co.,
Inc. @ $19.95. For information on the complete set, write the publisher at
4300 West 62nd St., Indianapolis, Ind. 46268.
o
ELEMENTARY ELECTRONICS
98
www.americanradiohistory.com
The Bug Killers
Continued from page 82
ever, certain liquid rocket propellants turned
out to be self -sterilizing. Researchers also
discovered that the broad panels of solar
cells, used to generate electric power on a
space flight, could provide shade and comfort to some germs. Solar cells are a spacecraft necessity, so Boeing is examining a potential antidote: the intense ultraviolet radiation in space may be a natural bug killer.
"The trip through the disagreeable environment of space might very well help us
decontaminate some parts of the spacecraft," Dr. Olson said.
Dropping the Other Shoe. There are
other tests, too -violent tests. Dr. Olson and
his staff have loaded test samples with microorganisms, then drop- hammered them onto
a steel base plate with the force of a locomotive crunching into a concrete wall at 100
miles an hour. The purpose is to see how
many organisms would live if hard impact
on a planetary surface becomes inevitable.
Dr. Olson also has put germs into plastic bullets and fired the bullets into sterile steel
canisters at velocities of 550 to 3100 feet
per sec. The findings: the higher the impact
force, the fewer organisms live through it.
Hey, Look Me Over
Continued from page 22
Boeing also conducted tests to see if
microorganisms, given a reasonably comfortable entry and landing, could actually
survive in a Martian environment. Data
from Mariner 4, a spacecraft which flew to
within 2400 miles of Mars, set the specifications for simulating the environment of
trace of water, basic limoanother planet
nite soil, a 70 per cent carbon dioxide atmosphere, strong sunlight, low temperature
and a reduction of atmospheric pressure. A
mixture of organisms, including Bacillus
subtilis spores, spent eight days and nights
in this environment, provided by a space
chamber. Dr. Olson found that as long as
the microorganisms are shaded in some way
and not exposed directly to solar radiation,
they will survive. Even now data from
Mariners 6 and 7 is backing up their find-
-a
ings.
However, the Boeing biologist had some
encouraging words. "We know very little
about Mars, only the information Mariners
4, 6 and 7 managed to give us," Dr. Olson
said. "These probes showed there is probably
less than one per cent water on the planet.
If this is true, terrestrial organisms most likely will not be able to grow and spread."
Even so, Dr. Olson afid his group are
working hard to make the odds one million
to one against an Earth bug finding a new
N
home on some other world.
ceiver input. You can install it on the back of
your SWL receiver with a screwdriver. Adaptable to any shortwave listening doublet, the
TRS -57 is $7.43 and more information can be
had from Mosley Electronics, Inc., 4610 N.
Lindbergh Blvd., Bridgeton, Mo. 63042.
Are You a Solid -State Experimenter?
Heathkit's new IP -28 regulated power supply should appeal to experimenters who work
with solid- state circuitry. Without using the
Mosely TRS -57 Transformer -Balun
Heathkit IP -28 Regulated Power Supply
band reception, eliminating the need for an additional antenna to receive local stations and
distant cities. On regular shortwave bands, the
TRS-57 acts as a balun to ptovide balanced re-
sensing terminals it delivers up to 30 VDC at
1
amp maximum load with less than 50 -mV
variation. There's a Remote Sensing feature
that reduces the voltage variation at the load
99
NOVEMBER- DECEMBER, 1969
www.americanradiohistory.com
to less than 20 mV. A front panel rocker
switch selects either 1 -10 VDC or 1 -30 VDC
ranges, and the output is continuously variable.
The IP -28 also has variable current limiting in
two switch -selected ranges from 10 -100 mA or
10 mA to 1 A. A 31/2-in. meter can be switched
to read either voltage or current, with two pilot
lamps indicating which is being monitored.
Styled in beige and brown like the rest of their
instrument line, Heath says the IP -28 goes together in about 8 hours with circuit board -wiring harness assembly. Price is $47.50 and you
can get more specs from Heath Co., Benton
Harbor, Mich. 49022.
lmmnnunolmullowttottnilinniontninuittoninnininanun111111111111111i1111111111InnninonnwrwrommunnimminnmumE
:nnn111111111111m1111m,nm1111111111111111111111m,m111mmn,1111111nnnm,nn,nm,nmmmn,n,mmm11nnn,mmmm11,m1mnmm11m111mnm:
&
Howell has devised the Road Runner cassette
tape player kit to keep them off your back. Besides the Road Runner cassette, six batteries
and earphone, the kit contains two original
tapes with stories, travel facts, behavior tips,
sing -along songs and games, all set to original
music. There's also a travel booklet and a special prerecorded cassette tape bonus offer. The
package comes in a sturdy travel carton with
handle and sells for $38.88. If you bought the
elements separately they would come to $45.00.
The Road Runner cassette features touch control for fast forward, play or stop, easy drop -in
cassette loading, and a rugged case. You can, of
course, use all standard cassette tapes in the
Road Runner. At your local dealer or write to
Bell & Howell, Video and Audio Products Div.,
7235 N. Linder Ave., Skokie, Ill. 60076.
Building the Kit. The KG -392 can rightfully be considered a kit only by the wildest
stretch of the imagination. The entire electronic circuit is supplied preassembled on a
printed circuit board; the wiring is also preassembled in a color-coded harness. The
builder simply drops the harness into position and solders about 30 connections.
An experienced builder took about 45
minutes to complete the kit; figure an hour
and a half for a beginner. One helpful assembly note: unlike the case with most kits,
you do not wrap the connections in the Sideman-the wires are prestripped for Via-in., so
don't try to strip to 1/4 in. Simply tack solder to all connections -even the selector
switch-and you'll have no problems.
How It Sounds. The KG -392's performance is quite good. The cymbal sounds like
a cymbal, the snare is reasonably a snare,
and the bass drum really booms. In fact,
the bass is excellent when the unit is fed
through a high quality music or hi -fi amplifier. With an inexpensive music amplifier, of
course, the bass comes out as a "klonk"
rather than a "thud" because the cheap,
small speaker cannot handle the low bass
tones and it frequency doubles and triples.
A complete set of level and effect controls
are provided which the user can easily adjust
(with no fear of causing damage) to the desired effect -balance and quality (such as
bass pitch and length).
The KG -392 Combo Sideman, priced at
$49.95, is supplied complete with output
cable, footswitch, and battery; an optional
AC power supply will be available. For additional information, write to Allied Radio
Corp., Dept. JR, 100 N. Western Ave.,
Chicago, Ill. 60680
Bell & Howell Rood Runner Cassette Kit
Beep -Beep! Beep -Beep!
Do the kids bug you on road trips? Bell
Knight -kit Combo
Continued from page 70
100
ELEMENTARY ELECTRONICS
www.americanradiohistory.com
Elementary Egotronics
En Passant
Continued from page
Continued from page
30
or lose a clear Knight. Here is the analysis:
A. If 42 KxB, Q -R6# 43 K -N1, RxN! 44
QxR, Q -N7 mate.
B. If 42 KxB, Q -R6# 43 K -K1 (43 K -B2,
QxRP# wins) RxN #! 44 QxR (44 K -Q1, R -Q6
wins) N -N7# wins the Queen.
C. If 42 KxB, Q-R6# 43 N -N2, NxN (or
43
. QxP #) 44 QxN, R -K8 #! 45 K -B2,
R-K7# 46 KxR, QxQ# wins.
D. If 42 NxB (White must recapture or
counter -attack) R -K7! 43 QxN (43 R -B8# only
delays it a move or two) Q -B7# 44 K -R1, QxN
mate.
E. If 42 N -B5, Q-R6 43 QxN, Q -N7 mate.
Q -R6 as
F. If 42 N -B5, Q-K8 (or 42
in E) 43 QxQ (43 QxN, B -R6 mate) RxQ 44
R -B8# K -R2 and Black still has mating threats
and a Bishop to the good.
Obviously, Black's 41st was a great deal more
than a simple capture!
....
Problem 21
By W. von Holzhausen
l
A
Ar
1e
i//i
''O/%//
''//%%
r4,/
//////
A
'//O/
she informs you in no uncertain terms that she adores
chess players but has immense contempt for men who
waste their time with electronic projects.
Would you:
tactfully discontinue the rela-
A.
Reluctantly and
tionship?
B.
Hopefully build her an electronic chess set?
Ask if she knows any girls who build oscillators?
Hit her in the mouth?
C.
D.
E
* * *
Alone one evening, you are enjoying a little
SWLing when you suddenly begin hearing a broadcast
identifying itself as emanating from an alien space7.
craft orbiting earth and from what the weirdly- voiced
broadcaster says, you realize it's no put-on.
Would you:
A. Feel quietly elated about the experience?
B. Decide it was only the result of that third martini?
C.
Visit
D.
Complain to the FCC?
a
psychiatrist?
E
German Chess Weekly, 1899
Black
43
so traumatic now, was it?
If you selected: mostly A- responses,;
you're Mister Keen; mostly B- responses,;
you're a cool character; mostly C-responses,
you could add tranquilizers to your present
diet; mostly D-responses, you're a real
loser. If you chose to write -in your own responses, you're probably a lot more creative
than you ever realized, man!
That wasn't
pommimumuminmmtumuumontnnumnremonlmminnummommunnumnonmrtmmnminnammmnumnnei
¡,.
W
ffi
White
White to move and mate in two.
Solution in next issue.
Herr Holzhausen's key is mighty shrewd!
Solution to Problem 20:1 Q-R6
If 1 . . . KxN 2 Q-R6 mate. If
1
1
....
.... PxN
K -N7 2 N -Q3 mate. And if
2 Q -R 1 mate.
News and Views. Three Americans flew to
Natanya, Israel, to compete in that city's Eighth
International Tournament. And they finished
one, two, three -Samuel Reshevsky, Pal Benko,
and Rev. William Lombardy.
101
NOVEMBER -DECEMBER, 1969
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Mark Ill Calibrator
Continued from page 36
on the IC pins, to a minimum. Keep the
iron well tinned and complete the soldering to the IC pins as quickly as possible to
avoid damaging the IC by excess heat. Also,
doublecheck each wire against the schematic
before soldering to be sure you are correct.
It's difficult to change connections on the
ICs. And the extra heat that may be applied
because of changes required to correct your
wiring can permanently damage the IC.
After mounting and wiring all components
on the board, give it a thorough inspection
to be sure there are no errors in wiring, cold
solder joints, or shorts created by excess
blobs of solder or clippings of wire. Mount
all of the controls to the housing, taking care
not to mar the lettering or the vinyl covering.
Mount the battery holder as shown in our
photo and then the circuit card. Use several
nuts as spacers to keep the wiring from
shorting to the housing. Connect the
switches, JI, and the battery to their respective points on the circuit card. You may
want to put a dab of red to identify the positive contacts of the battery holder.
Testing and Aligning. Now we're ready
to enjoy the benefits of our hard ( ?) work,
but first let's check out and align our calibrator. Insert three AA cells in the battery
holder, taking care to observe correct polarity. Before doing so, be sure power switch
S2 is
oi.
Loosely couple the output of the calibrator through a 10 -50 pF capacitor to the
input of a receiver that has been warmed up
and is operational. Place output selector
switch S3 of the Mark III to the 100 7jcHz
position and turn its power switch on. If the
unit is working you should be able to pick
up strong marker signals at 100 -kHz intervals across the band. Nett tune in one of the
marker signals and turn Ident switch S1 on.
The marker signal should pulse on and off
about twice a second. Repeat these steps with
S3 placed at the 50- and 25-kHz positions
and observe markers at these intervals.
If you cannot receive the marker signals
first check battery polarity, then for shorts
that may have developed in mounting and
interconnecting the controls and the circuit
card. Then check the circuit around the 100 kHz crystal oscillator. Check the polarity of
capacitors C4 and C5, as well as for voltage
at pins 8, 9, and 11 of ICI and pin 11 of
1C2. If everything checks out you may have
a defective IC, which may have been damaged in soldering.
If you cannot get marker signals when S3
is placed in the 50 -kHz or 25 -kHz positions,
check wiring to IC2. If this proves correct,
IC2 will have to be replaced. If you cannot
get the identification pulses when Si is
closed, check the switch and also for wiring
errors in the 2 -Hz multivibrator.
WWV Calibration. To be most useful,
the Mark III must be accurately calibrated.
Once this is done it should remain on frequency. Calibrating with WWV is very easy
to do. Tune your receiver to the 5 -, 10 -, or
15 -MHz WWV signals-whichever you receive best in your location. Set S3 on the
calibrator to 100 kHz, loosely couple its output to the input of the receiver, and turn
on the calibrator. Adjust Cl until the output
of the Mark III zero beats against WWV's
signal. That's all you have to do to calibrate
the unit.
.11111111111111/1111,,,,,, 111?1,/1111,1111,111111111,111,11111111111111,1111111111111,1111111111111111111.11,,,11111111
Darkroom to Color
Continued from page 42
It appears too dark and too blue, doesn't it?
The secret of viewing wet color prints is to
use transmitted light, i.e., to allow the light
to come through the wet print from the rear.
This method is satisfactory for quick viewing, but it's best to dry the print completely
before making any color corrections to the
filter pack.
We strongly advise referring to the Kodak
Color Dataguide for color correction. The
color viewing filters contained in the Data-
guide are indispensable for modifying the
filter pack. However, you can also use a
color printing filter or follow the correction
guides furnished with the set of filters. With
a little practice you can become an expert in
modifying the filter pack.
The total cost of converting to color
processing should be less than $75.00. This
includes the CP -5 processing kit and 25
sheets of Ektacolor professional paper.
Since the secret of tray-processing of color
lies in the heat conductivity of stainless -steel
trays, here's a money -saving tip: Sears -Roebuck has stainless-steel cake pans 9 x 13 x 2
in. for less than $3.00 that are ideal for color processing.
ELEMENTARY ELECTRONICS
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NOVEMBER- DECEMBER, 1969
103
www.americanradiohistory.com
You can earn more money
if you get an FCC License
...and here's our famous CIE warranty that
you will get your license if you study with us at home
SATISFIED with your present income?
The most practical thing you can do
about it is "bone up" on your electronics,
pass the FCC exam, and get your GovernNNOT
ment license.
The demand for licensed men is enor-
mous. Ten years ago there were about
100,000 licensed communications stations,
including those for police and fire departments, airlines, the merchant marine, pipelines, telephone companies, taxicabs, railroads, trucking firms, delivery services, and
so on.
Today there are over a million such stations on the air, and tfie number is growing
constantly. And according to Federal law,
no one is permitted to operate or service
such equipment without a Commercial FCC
License or without being under the direct
supervision of a licensed operator.
This has resulted in a gold mine of new
business
for licensed service technicians. A
typical mobile radio service contract pays
an average of about $100 a month. It's possible for one trained technician to maintain
eight to ten such mobile systems. Some men
cover as many as fifteen systems, each with
perhaps a dozen units.
Coming Impact of UHF
This demand for licensed operators and serve
Ice technicians will be boosted again in the
next 5 years by the mushrooming of UHF
television. To the 500 or so VHF television
stations now in operation, several times that
many UHF stations may be added by the
licensing of UHF channels and the sale of
10 million all- channel sets per year.
Opportunities in Plants
And there are other exciting opportunities
in aerospace industries, electronics manufacturers, telephone companies, and plants operated by electronic automation. Inside industrial plants like these, it's the licensed
technician who is always considered first for
promotion and in -plant training programs.
The reason is simple. Passing the Federal
government's FCC exam and getting your
license is widely accepted proof that you
know the fundamentals of electronics.
So why doesn't everybody who "tinkers"
with electronic components get an FCC License and start cleaning up?
The answer: it's not that simple. The government's licensing exam is tough. In fact,
an average of two out of every three men
who take the FCC exam fail.
There is one way, however, of being pretty
certain that you will pass the FCC exam. And
that is to take one of the FCC home study
courses offered by the Cleveland Institute
of Electronics.
CIE courses are so effective that better
than 9 out of every 10 CIE -trained graduates
who take the exam pass it. That's why we can
afford to back our courses with the iron -clad
Warranty shown on the facing page: you get
your FCC License or your money back.
There's a reason for this remarkable record. From the beginning, CIE has specialized
in electronics courses designed for home
study. We have developed techniques that
make learning at home easy, even if you've
had trouble studying before.
In a Class by Yourself
THESE CIE MEN PASSED THE FCC
LICENSE EXAM
NOW THEY
HAVE GOOD JOBS
Matt Stuczynski,
Senior Transmitter
...
Operator, Radio
Station WBOE
"I give Cleveland Institute credit for my
First Class Commercial
FCC License. Even
though I had only six
of high school
algebra, CIE's AUTO weeks
PROGRAMMEDt
lessons make electronics theory and fundamentals easy. I
now have a good job in studio operation,
transmitting, proof of performance, equipment servicing. Believe me, CIE lives up
to its promises
Chuck Hawkins,
Chief Radio
Technician, Division
12, Ohio Dept.
of Highways
Your CIE instructor gives his undivided personal attention to the lessons and questions
you send in. It's like being the only student
in his "class." He not only grades your work,
he analyzes it. Even your correct answers
can reveal misunderstandings he will help
you clear up. And he mails back his corrections and comments the same day he receives your assignment, so you can read his
notations while everything is still fresh in
your mind.
It Really Works
Our files are crammed with success stories
of men whose CIE training has gained them
their FCC "tickets" and admission to a higher
income bracket.
Mark Newland of Santa Maria, Calif.,
boosted his earnings by $120 a month after
getting his FCC License. He says: "Of 11
different correspondence courses I've taken,
CIE's was the best prepared, most interesting, and easiest to understand."
Once he could show his FCC License, CIE
graduate Calvin Smith of Salinas, California,
landed the mobile phone job he'd' been after
for over
a
"My CIE Course enabled me to pass both
the 2nd and 1st Class
License Exams on my
first attempt...I had no
prior electronics training either. l'm now in charge of Division
Communications. We service 119 mobile
units and six base stations. It's an intéresting, challenging and rewarding job. And
incidentally, I got it through CIE's Job
Placement Service."
ENROLL UNDER NEW G.1. BILL: All CIE
courses are available under the new G.1.
Bill. If you served on active duty since
January 31, 1955, OR are in service now,
check box on reply card for G.I. Bill
r
information.
Cleveland Institute of Electronics
1776 E. 17th St., Cleveland, O. 44114
year.
Please send me without cost or obligation:
Year 40 -page book' "How To Succeed In
Electronics" describing the fob opportunities in Electronics today, and how your
courses can prepare me for them.
Your book on "How To Get A Commercial
Mail Card for Two Free Books
Want to know more? The postpaid replx card
bound -ìn here will bring you free copies of
License."
FCC
our school catalog describing opportunities
in electronics, our teaching methods, and our
courses, together with our special booklet
"How to Get a Commercial FCC License.'
If tard has been removed, just mail the coupon at right.
I
am especially interested in:
°
FCC
2 NEW
CIE CAREER
COURSES
1. BROADCAST (Radio and TV) ENGINEERING... now Includes
Video Systems, Monitors, FM Stereo Multiplex, Color Transmitter Operation and CATV.
2. ELECTRONICS ENGINEERING...covers steady-state and transient network theory, solid state physics and circuitry, pulse
techniques, computer logic and mathematics through calculus.
A college -level course for men already working in Electronics.
Elcic
Electronics
Technolog
Broadcast
Engineering
First Class
Name
Coetronmmunications
Industrial
Electronics
Electronics
Engineering
License
MUSE
0111en
A ddre ss
City
State
Zip
One_
Check here for G.I. Bill information
CIE
Cleveland Institute of Electronics
177E East 17th Street. Clov llanO,Chio 44114
i
EL -17
tELEMENTARY ELECTRONICS
104
www.americanradiohistory.com
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of success in obtaining a
Government FCC License
The Clevelani: Institute of Electronics hereby warrants that
upon completion of the Electronics Technology, Broadcast
Engineering, or First -Class FCC License course, you will be
able to pass the FCC examination for a First Class Commercial RadioTelephone License (with Radar Endorsement) ;
OR upon completion of the Electronic Communications
course you will be able to pass the FCC examination for a
Second Class Commercial Radio Telephone License;
AND in the event that you are unable to pass the FCC test
for the course you select, on the very first try, you will receive a FULL REFUND of all tuition payments.
This warranty is valid for the entire period of the completion time allowed for the course selected.
.
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www.americanradiohistory.com
°
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PRINTED CIRCUITRY
no increase in price, the ''Edu -Kit"
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
now
TV sets.
A Printed Circuit is 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.
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