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make learning Electronics at home fast and fascinating give you priceless confidence. Some NRI in training equipment v¡ firsts 'ftzt, . T.... óó _y Q º - i.üY8]-. ....~,.'.Va

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a TTyya`` _11117to give you Color Television training I I ISEto give you a unique, exciting digital equipment engineered specifically for education - computer with memory built especially for home train- built to fit NRI instructional material, not a do-it- ing. You learn organization, trouble shooting, opera- yourself hobby kit. The end product is a superb tion, programming as you build and use it. Performs Color TV receiver that will give you and your family the same functions as commercial computers. Lessons years of pleasure. You "open up and explore" the stress computer repair. You conduct a hundred ex- functions of each color circuit as you build. periments, build hundreds of circuits. A solid-state VTVM is included among ten training kits. NRI's "discovery" method is the result of over half a century of leadership simplifying and dramatizing training at home

The FIRSTS described below are typical of NRI's half century of leadership in Electronics home training. When you enroll as an NRI student, you can be sure of gaining the in -demand technical knowledge and the priceless confidence of "hands-on" experience sought by employers in Communications, Television -Radio Servicing and Industrial and Military Electronics. Everything about NRI training is designed for your education ... from the much -copied, educator-acclaimed Achievement Kit sent the day you enroll, to "bite -size" well -illustrated, easy to read texts programmed with designed -for -learning training equipment.

YOU GET YOUR FCC LICENSE OR YOUR MONEY BACK There is no end of opportunity for the trained man in Electronics. You can earn $6 or more an hour in spare time, have a business of your own or qualify quickly for career positions in business, industry, government. And if you enroll for any of five NRI courses in Communications, NRI prepares you for your FCC License exams. You must pass or NRI refunds your tuition in full. No school offers a more liberal money -back agreement, The full story about NRI leadership in Electronics training is in the new NRI Catalog. Mail postage -free card today. No salesman is going to call. NATIONAL RADIO INSTITUTE, Washington, D.C. 20016

APPROVED UNDER NEW GI BILL If you have served since January 31, 1955, or are in service, check GI line on postage-free card. designed from chassis up for your education

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Iirst to give you true-to-life experiences as a Ibeiiost to give you completely specialized communications technician. Every fascinating step training kits engineered for business, industrial and you take in NRI Communications training, including military Electronics. Shown above is your own train- circuit analysis of your own 25 -watt, phone/cw ing center in solid state motor control and analog transmitter, is engineered to help you prove theory computer servo-mechanisms. Telemetering circuits, and later apply it on the job. Studio equipment solid-state multi -vibrators, and problem -solving operation and troubleshooting become a matter of digital computer circuits are also included in your easily remembered logic. course.

FEBRUARY 1972 3 VOLUME I NUMBER 2 FEBRUARY 1972 WORLD'S SLARGEST -SELLING Popular Electronic ELECTRONICS MAGAZINE INCLUDING Elect ronics World

FEATURE ARTICLES

26 NUCLEAR RADIATION-INSIDIOUS POLLUTER Forest H. Belt Many benefits are to be derived from the controlled use of nuclear energy in peaceful applications. Electronics plays o role in keeping pollution down. 37 CLASS "E"-CB OF THE FUTURE? The possibility of a new band for Citizens Radio Service.

40 THE ART AND TECHNOLOGY OF ELECTRONIC MUSIC David L. Heiserman "Synthetic" music is not ersatz or fake. Properly engineered and competently performed it is genuine and eminently enjoyable. 49 COMPUTER CORE MEMORIES STILL HANDMADE 50 NEW IC'S AND CIRCUITS FOR COLOR TV Integrated circuits are coming into their own-along with other solid-state devices-to provide improved TV. 58 FUNDAMENTALS OF SOLID-STATE RECIEVERS Jim White An understanding of basics of receiver design shows how new IC's and circuits can improve performance.

102 GETTING THE MOST FROM YOUR SERVICE DOLLARS John T. Frye Mac's Service Shop answers some questions and provides some good advice on getting your TV in working order. CONSTRUCTION STORIES

32 PRECISION LAB POWER SUPPLY C. H. Ball, Jr. A well -regulated supply of ample capacity (30V and 1.2A) that is a must for the experimenter and service technician.

45 BUILD THE SURF SYNTHESIZER John S. Simonton, Jr. The relaxing sound of the sea on the shore produced electronically. 68 TUNER FOR THE NEGLECTED BAND Jim White

ZIFF-DAVIS PUBLISHING COMPANY POPULAR ELECTRONICS Including ELECTRONICS WORLD, Editorial and Executive Offices February 1972, Volume 1, Number 2. Published monthly at One Park Avenue, New York, New York 10016 One Park Ave., New York, NY 10016. One year subscrip- 212 679-7200 tion rate for U.S., U.S. Possessions and Canada, $6.00; all other countries, $7.00. Second class postage paid at New William Ziff, President York, N.Y. and at additional mailing offices. Authorized W. Bradford Briggs, Executive Vice President as second class mail by the Post Office Department, Hershel B. Sarbin, Senior Vice President and Secretary Ottawa, Canada and for payment of postage in cash. Stanley R. Greenfield, Senior Vice President Subscription service and Forms 3579: P.O. Box 1096, Philip Sine, Financial Vice President and Treasurer Flushing, NY 11352. Editorial offices for manuscript con- Philip T. Heffernan, Vice President, Marketing tributions, reader inquiries, etc.: One Park Ave., New York, Frank Pomerantz, Vice President, Creative Services NY 10016. Arthur W Butzow, Vice President, Production Edward D. Muhlfeld, Vice President, Aviation Division POPULAR ELECTRONICS Including ELECTRONICS WORLD Irwin Robinson, Vice Persident, Travel Division is indexed in the Reader's Guide to Periodical Literature. George Morrissey, Vice President Sydney H. Rogers, Vice President Copyright © 1972 by ZIFF-DAVIS PUBLISHING COMPANY. Lawrence Sporn, Circulation Director All rights reserved.

4 POPULAR ELECTRONICS Including Electronics World EDGAR W. HOPPER ALEXANDER W. BURAWA JOSEPH E. HALLORAN Publisher Associate Editor .I,I rrrti.,.i ng Director WM. A. STOCKLIN ANDRE DUZANT RICHARD J. HALPERN Editorial Director Technical Illustrator Adrerti.4i ag Manager MILTON S. SNITZER Editor JUDITH L. HOGAN MADELEINE LITTMAN Editorial Assistant $orrice ]lonuger LESLIE SOLOMON Advertising Technical Editor FOREST H. BELT STANLEY NEUFELD JOHN T. FRYE Associate Pehllsarr, JOHN R. RIGGS DAVID L. HEISERMAN Managing Editor J. GORDON HOLT FURMAN H. HEBB EDWARD I. BUXBAUM RICHARD HUMPHREY Group Vice President Art Director Contributing Editors Electronics itnd Photographic

THE SCENES

10 STEREO SCENE J. Gordon Hoff Basic troubleshooting for hi-fi 64 COMMUNICATIONS SCENE Richard Humphrey The case for a national CB organization 94 TELEVISION SCENE Forest H. Belt Is the Trinitron tube still a mystery? PRODUCT TEST REPORTS 76 ADVENT 201 CASSETTE TAPE DECK 79 EICO EC -4700 4 -CHANNEL STEREO ADAPTER 80 MIDLAND 13-873 SSB/AM TRANSCEIVER 82 KOSS KRD-711 RED -DEVIL STEREO HEADPHONES 84 SIMPSON 460 DIGITAL VOLTOHMMETER 85 LEADER LS -5 ELECTRONIC OSCILLOSCOPE SWITCH 88 JFD STELLAR -2001 ALL -CHANNEL TV ANTENNA DEPARTMENTS

6 EDITORIAL Milton S. Snitzer 8 LETTERS 23 NEWS HIGHLIGHTS 89 OUT OF TUNE Pioneer PL -12A Record Player, January 1972 VHF Frequency Converter, December 1971 106 ELECTRONICS LIBRARY 112 NEW PRODUCTS 116 NEW LITERATURE

READER SERVICE CARD ON BACK COVER

Midwestern Office Ziff -Davis also publishes Boating, Car and Driver, Cycle, The Pattis Group, 4761 West Touhy Ave., Flying, Modern Bride, Popular Photography, Skiing, and Lincolnwood, Illinois 60644, 312 679-1100 Stereo Review. GERALD E. WOLFE, DICK POWELL DICK GOVATSKI, MANLEY LUDWIG Forms 3579 and all subscription t:orrespondence should be Western Office addressed to POPULAR ELECTRONICS Including ELEC- 9025 Wilshire Boulevard, Beverly Hills, California 90211 TRONICS WORLD, Circulation Department, P.O. Box 1096, 213 CRestview 4-0265; BRadshaw 2-1161 NY 11352, Please least weeks for Western Advertising Manager, BUD DEAN Flushing, allow at eight change of address. Include your old address, as well as Japan: James Yagi new-endosing, if possible, an address label from a Oji Palace Aoyama; 6-25, Minami Aoyama recent issue. 6 Chome, Minato-Ku, Tokyo 407-1930/6821

Editorial contributions must be accompanied by return postage and will be handled wfh reasonable care; how- Member Audit Bureau ever, publisher assumes no responsibility for return or of Circulations safety of art work, photographs or' martuscripts.

FEBRUARY 1972 5 Editorial

Sy Milton S. Snitzer, Editor

NEW DEVELOPMENTS IN AUDIO

When we visited the Audio Engineering Society Show not long ago, we found lots of interest in things old and new. For example, one of the technical sessions featured a paper on a "Modulated Air Flow Direct Radiator Loudspeaker" by Dr. Harry Olson of RCA Laboratories. The low -frequency speaker uses a high -velocity fan to force air through a rectangular opening whose size is varied. The air -flow woofer, strictly a laboratory development, occupies only one -eighth cubic foot. Other papers in the same session were analyses of bass -reflex speaker enclosures. Although this type of enclosure has been with us for many years, its operation is still not fully understood. And just now its characteristics are being studied through the use of computer design techniques. Most of the excitement at the show for audio professionals was in the area of 4 -channel or quadraphonic sound. There were professional encoders which take four separate channels from a master tape, encode it by several different matrixing and signal -handling techniques, and produce a 2 -channel output containing a mixture of the four channels. The two channels can then be cut onto a disc, a 2 -track tape, or transmitted over the air by FM broadcast. We saw and heard equipment from CBS Labs, Sansui, and Electro -Voice. All of this equipment produced some pretty effective demonstrations of quadraphonic sound. Unfortunately, however, each system uses different matrixing arrangements, gain -riding circuits, and phase shifters to produce what each company considers to be the best results. All systems claim good compatibility-that is, the encoded signals can be played back on regular 2 -channel or even monophonic equipment with little or no loss of information. All systems also claim good separation and no degradation of sound quality. What's more, a number of commercial records or demonstration discs have already been pressed using the various encoders, and four -channel broadcasts using both Electro -Voice and Sansui encoders are being made. While all systems claim stereo and mono compatibility (though CBS Records is making separate discs for 2- and 4 -channel use), they are not compatible with each other. That is, a disc encoded with one of these systems will work using a decoder designed for another system, but the results will not be optimum. A step forward in this direction is a recent announcement by Electro -Voice that they have developed a circuit which is fully compatible with the CBS system. It seems everyone is rushing to be there first-which is a little hard on the consumer, who would best be served by one standardized, agreed -upon system that everyone could use. But in the meantime, if you want quadraphonic sound now, there are plenty of equipment and records around to make it worth your while.

6 POPULAR ELECTRONICS Including Electroni:s World 70~4'1 introductory offer to new members of the ELECTRONICS AND CONTROL NGINEERS' BOOK CLUB

107/971 286/515 yyam- ELECTRONIC _ ! INTEGRATED CIRCUITS: CIRCUITS: ' PHYSICAL A Basic Course PRINCIP for Engineers {!üOM ANALYSILES,SAND and Technicians DESIGN by R. G. Hi bbe rd D - by P. M. Chirlian Pub. price, 59.95. ;i! Pub. price. $15.50 Club price, $8.45 Club price, 513.25 L. books 637/458 497/265 of DESIGNING í d R."", ELECTRONIC great pessionalrOW WITH M. SWITCHING. of these INTEGRATED TIMING AND CIRCUITS PULSE CIRCUITS. 00 by Texas 2/e Instruments for by Pettit & Inc. McWhorter Pub. price. $18.50 a Pub. price. $12.50 Club price. 513.50 Club price. $8.95 only 313/059 404/437 HANDBOOK OF SOURCEBOOK SEMI- OF ELECTRONIC to $34.75 CONDUCTOR $g95 CIRCUITS FROM ELECTRONICS, VALUES by J. Markus 3/e Pub. price, 519.75 by P. Hunter Special $1.00 bonus book Club price. 514.75 Pub. price, $27.50 comes to you with your Club price, $21.50 . first club selection 306/470 259/607 ACTIVE FILTERS: 621/616 t¡'""a^ COMMUNICA- LUMPED, 494/754 WAVE I 114 TION SYSTEM `P ENGINEERING t DISTRIBUTED, GENERATION i's- ENGINEERING INIEGRATEO, MANUAL, 2/e AND SHAPING, HANDBOOK DIGITAL & by R. H. Perry 2/e , r by PARAMETRIC by L. Strauss D. H. Hamsher it - by Pub. price, 112.50 : P. f m Pub. price, $16.50 Pub. Drive, $29.50 L. Huelsman Club price, $9.95 '' Club price, $22.50 Pub. Drive, $16.50 " Club price, 513.95 Cltb price, $13.95 209/731 158/215 124/035 - HANDBOOK 654/301 STANDARD AN f HANDBOOK OF ENGINEERING HANDBOOK FOR INTRODUCTION p8ySIf$ PHYSICS, 2/e MATHEMATICS ELECTRICAL TO ELECTRONIC ,% by Condon and HANDBOOK ENGINEERS, COMPUTERS, 2/e Odishaw by J. J. Turna 10/e by G. B. Davis ' - Pub. price, 534.75 - s,'Iiiir, Pub. price, 59.95 by Fink and Pub. price, $12.50 `, Club price, $14.95 - Carroll Il .-. Club price, $8.45 Pub. Club price. 59.30 - price, $32.50 Club price, $24.95 MAIL THIS COUPON TODAY Save time and money by joining the n Y r Electronics and Control Engineers' Book Club ELECTRONICS AND CONTROL ENGINEERS' BOOK CLUB 582 Princeton Road, Hightstown, N.J. 08520

Please enroll member of the Electronics and HERE is at professional club designed specifically to meet your m Control Engi- neers' Book Club andsend see the two books indicated below. I am day-to-day engineering needs by providing practical books to receive the bonus for just 51.00. and my first selection at the in your field on a regular basis at below publisher prices. special Club price shown. These baoks are to be shipped on approval. and I them without How the Club operates: Basic to the Club's service is its publi- mar return both cost or further obligation. If I decide to keep the hooka, 1 agree to purchase as few cation, the Electronics and Control Engineers' Book Club ,: four hooks during the next two years at special Club prices (at Bulletin, which brings you news of books in your field. Sent to least 14e1 below list). members without cost, it announces and describes in detail.the Write Code No. of Write Code No. of Club's featured book of the month as well as alternate selections bonus book first selection which are available at special members' prices. here here When you want to examine the Club's feature of the month, you do nothing. The book will be mailed to you as a regular part of your Club service. If you prefer one of the alternate selections-or if you want no book all at for that month-you notify Name the Club by returning the convenient card enclosed with each Bulletin. Address As a Club member, you agree only to of the purchase four City books over a two-year period. Considering the many books published annually in your field, there will surely be at least four State Zip would that you want to own anyway. By joining the Club, you E33172 save both money and the trouble of searching for the best books. J CIRCLE NO. 19 ON READER SERVICE CARD

FEBRUARY 1972 7 Johnson put it all together Letters } low band and high band channels in any combination O base ADVICE and mobile operation with built- PATENT ATTORNEY GIVES FREE reading non-professional in supply O auto -scan with I am constantly power advice about inventions and patents. Read- push-button "lock out" plus man- ing greatly over -simplified material, the in- ual "lock in" ventor can be lulled into the complacent belief that the whole matter is really quite simple; but patents are extremely' complex matters. Mr. A. S. Dubar, in an Interface new letter [July 19711 mentions the Patent Of- fice "Disclosures Document Program" and Duo.ScanTM writes: "The inventor can then describe his invention to possible manufacturers without fear of loss of his patent office dis- $195 from closure." Nothing could be further the truth. If an inventor does nothing more than he is extremely vul- It,¡,M.. ti disclose his invention, 1-1; nerable to complete loss of his invention and any patent rights he might seek. If he . his disclosure, goes no further than writing if no matter how well it can be proved, another person, by reducing the invention to -_ practice or by filing a patent application, can take over the entire invention both properly and legally. . An inventive concept is not a completed invention. In order for the original inventor to protect his rights, he must diligently Eight VHF FM channels, in any combination perfect his invention or file a patent or file of high and/or low band, keep you on top a patent application. Even then he has no will he granted. the action. Operates mobile or base assurance that a patent of all Beware of over -simplifica- features previously My advice is: with performance tions! found only in professional public safety ALFRED W. BARBER radio equipment. Two ceramic filters give Registered Patent Attorney unsurpassed adjacent channel rejection. Flushing, N.Y. Integrated circuit symmetrical limiting. Vera true! In fact, in November's "Oppor- lets makes it really quiet. 0.4 µV sensitivity tunity Awareness", Duce Heiserman gave you hear what others miss. Powerful tran- quite a bit of helpful information on how important sistor audio produces clear, undistorted to obtain a patent-his most that the very first step is to sound. The new Duo -Scan puts if all point being consult a registered patent attorney. together, for just $169.95 (less crystals). NO CHANGES NEEDED I built "The Drummer Boy" ( July 1971) COMPANY from a kit which I purchased from PAIA Elec- E.F.JOHNSON I happy to report that it 5 6 0 9 3 tronics, Inc. am W E CA, MINNESOTA AS worked perfectly the first rime I turned it on and adjusted it. I connected the Drummer Bov CIRCLE NO. 25 ON READER SERVICE CARD POPULAR ELECTRONICS Including Electronics World 8 to my wife's Thomas organ, and she is very pleased with the way it works. In the October 1971 issue, some corrections to the Drummer Boy were given (Out Of Tune). I can see no reason for making any changes since it works just fine. F. BmESE SWVEARINGEN Miami Springs, Fla.

Reader Swearingen has put his finger on one of the most important benefits that can be derived from purchasing a kit of parts from the sources listed in POPULAR ELECTRONICS COn- struction articles. This is that any errors which inadvertently creep into the article or any The secret of changes that will make the project less costly or operate better will become part of the kit. teaching yourself Ilence, even though a few errors might have been in the published article, the kit and in- music structions that accompanied zt took into ac- It's organized common sense, says count those errors. just this 70 -year -old home -study school. Their word - and -picture instructions take the mystery out MAIL-ORDER PARTS of learning the piano, guitar, or any of 8 It sometimes happens that electronics hobby- other instruments. ists who buy parts via It may seem o(1(1 at first-the idea of teaching mail experience slow yourself music. You might think you need delivery. The result is often a flow of nasty let- an expensive private teacher to instruct you- ters to the supplier, the magazine involves), the and to tell you when you make a mistake. Better Business Bureau, etc., If the parts do not But the fact is, you don't. Thousands have arrive within a reasonable time. learned music with the lessons we give by Being a parts supplier (we furnished the kit mail. So can you. The secret lies in the step-by-step way our for the "Underwater Fish Detector,' August lessons teach you. Starting from scratch, they 1971), I am painfully aware of this situation. show you with simple words and pictures On one hand, I feel- personally responsible to exactly what to do. You learn to play the right the people who have way-by note, from sheet music. Without gim- sent in their hard-earned micks or gadgets. money for the kit; but on the other hand, I How (lo you know you're doing it right? wonder how my suppliers, distributors, and Easy. A lot of the tunes you'll practice first are original equipment manufacturers feel about the simple songs you've heard many times. So spot they have put me in by failing to ship to you'll know when you've "got them right." me for some reason or another. Then, once you get used to playing correctly by note, you move on to more advanced pieces. One company has been promising for months Before too long, you're playing any kind of mu- to ship me 250 potentiometers. Although we sic you like. Popular. Falk. Classical. Hymns. have finally received 150 pots, we are again For more information, just mail the coupon. hearing a story about future delivery delays. We'll send you our free booklet, Be Your Own Music Teacher, and a free Piano "Note- Consequently, we have been torced to ship out Finder." No obligation. about 70 kits without the pot and to ship, at U.S. School of Music. Estab. 1898, Lic. by N.Y. our own expense, the pots when we receive State. them. r I would like to thank our many customers U.S. School of Music for their patience and to assure them that they Port Washington, New York 11050 have not been forgotten. I'm interested in learning to play the instrument W.L. GREEN checked below. Please send me your FREE booklet. Be Your Own Music Teacher, and a free Piano President "Note-Finder." I am under no obligation. Check the Alpha Research Corp. instrument you would like to play: (check only one) Cl Piano Steel Guitar Accordion U -CHANNEL SUPPLIERS Guitar Saxophone Mandolin Where can I buy the %" x 14" aluminum Organ-pipe, Violin Clarinet U -channel specified for the booms in the "Mini - electronic, reed Ukulele Pyramidal UI-IF TV Antenna" article ( December Print 1971 )? No one in my area handles this item. Name Age_ PAUL BOCDANOFF Address Philadelphia, Pa. City State Zip 7'19 your local hobby shop or curtain ron Accredited Member. National Home Study Council ' U. S. School of J'iusic 3'732 supplier. L6)1969 J

FEBRUARY 1972 9 e, Al Stereo Scene By J. Gordon Holt

ONE of the most attractive features of things we do not even care to admit to solid-state circuitry is supposed to be its our best friends (like leaving the tape dependability. Tubes were nice in many switch in the monitor position while trying respects ( and indeed, some tube -type to listen to FM) . equipment sounds as good, if not better, Let's consider first the condition of both than some of the top solid-state components), channels being dead. If this is the case, but it must be admitted that tube -type on one program source only, obviously components often contained the seeds of that is the source of the trouble; their own destruction-what insurance and about all you can do is check to make policies call "inherent vice." They sure it is getting ac (showing signs of life generated large amounts of heat, and heat like a lit pilot light or a wisp of smoke) shortens the lives of resistors and capacitors. and that it is connected to the amplifier. Li addition, tube-type components required If all inputs are dead, though, the trouble rather high operating voltages. is at or around the amplifier. Transistors were supposed to do away Most important: if your system is dead with these problems, which in fact they or operating at lower -than -normal have, almost. Resistor and capacitor volume, do not try to "clear the tracks" breakdowns are relatively rare in solid- by cranking up the volume control. The state equipment; but, while transistors don't trouble may be between the amplifier usually go gradually downhill with age as outputs and the loudspeakers, and the do tubes, they have not thus far proven result could be damage to or destruction all that much more dependable. So solid- of the power amplifier. Alternately, you state components sometimes need servicing, just might manage to break through the too. And, when problems arise, the first "obstruction" in the system, if it happens question the audiophile must answer is to have a barely intermittent condition, "Which component is defective?" and then you could blow your loudspeakers. Almost a third of all home audio system If the amplifier's pilot light is lit, you can "malfunctions" are not even the result of assume it is getting ac power. If not, component failure. They are the result of make sure it is plugged into and making ridiculously simple things like corroded contact with a properly energized wall plugs, broken wires, and-occasionally- outlet, and that its ac switch is on. Sometimes fuses blow without showing any visible evidence. Try another one, and then plug something like a table lamp into a switched ac outlet to make sure the amplifier's power switch is working. asic Hi -Fi You've Got Power. Now, let's say the pilot light goes on, but all input sources are still dead. (If you only have one input source, switch the selector to Trouble - another position and insert a small nail about a quarter of an inch into either of those input sockets. If there's no hum, all Shooting inputs are dead.) First check to make sure

CIRCLE NO. 7 ON RENDER SERVICE CARD--> UNANIMOUS ACCLAIM! First test reports on the Zero 100 by the industry's leading reviewers Brief excerpts reprinted below.. Let us send you the full reports.

AUDIOJuly, 1971 Stereo Review FEELITY Sep,. 1971 Altogether, this new arm strikes us as an The Zero -100 performed just about as we Indeed, everything worked smoothly, excellent piece of engineering: it prob- expected after reading the specifications. quietly. and just as it was meant to. If ably is the best arm yet offered as an Wow measured .08 per cent - that is in there were any "bugs" in the Zero 100, integral part of an automatic player. the band from 0.5 to 6 Hz. Flutter, in the we didn't find them. Garrard's Zero Operation is simple, quiet, and reliable. band from 6 to 250 Hz, measured .03 per 100, in basic performance, easily ranks All told, we feel that Garrard has come cent, both of which are excellent. Thus, with the finest automatic turntables on up with a teat winner in the Zero 100. the Garrard Zero 100 is certainly the the market Its novel arm-which really Even without the tangent -tracking feature linest in a long fine of automatic turn- works as claimed - and its other unique of the arm, this would be an excellent tables which have been around for over design features suggest that a great deal machine at a competitive price. With the 50 years. We think you will like it. of development time, plus sheer imagina- novel (and effective) arm, the Zero 100 tion, went into its creation. In our view, becomes a very desirable "superchanger" the results were well worth the effort. with, of course, manual options.

Popular Electronics Aug,,,,,

Sept. re. 1971 Our lab measurements essentially con- ~ISM The GRA MOPHONE August, 1977 firmed the claims made by Garrard for the Zero 100. We used a special pro - This unit has every imaginable, gadget Reproduction quality was excellent with 'tractor with an angular resolution of about and gewgaw one might possibly desire, no detectable wow, flutter or rumble 0.5°, and the observed tracking error was and it works. And considering how much under stringent listening conditions. End always less than this detectable amount. it does, and how well it does it, at 190 of side distortion, which is always a pos- The tracking force calibration was accu- bucks it doesn't even seem expensive. sibility with pivoted arms, was virtually rate, within 0.1 gram over its full range. The changer has so much in it that an absent, due no doubt to the tangential The Garrard Zero 100 operated smoothly analysis al its innards is almost a case tracking arm. and without any mechanical "bugs." study in record player design.

HI-FI o Fall, 1971

One could go on cataloguing the virtues of the Zero 100 indefinitely.

I *mum 1 For B.page lest reports booklet and a 12.page brochure on the Zero 100 and the entire Garrard series mail to British Industries Company, Oept.B232, Westbury, N.Y. 11590.

A genuine step upward in automatic turntables GARRARD ZERO 900 The only automatic turntable with Zero Tracking. Error $18960 MIg. by Plessey Ltd. Dist. by British'ndustries Co. less base and cartridge

FEBRUARY 1972 ill the loudspeakers are connected (or Now, Find the Circuit You headphones plugged in) and that every tape monitor switch in the system is set where Need-in Minutes! it belongs. Many add-on devices like equalizers have their own monitor ALL NEW! switches, duplicating the function of the one on the amplifier, and it is Over 3,000 advanced elec- easy to remember tronic circuits in one mas- one and forget the other. ter volume. Locate any If everything is still dead, start application in minutes. dismantling. Beats any computer re- Remove all plugs from the trieval system now in amplifier's tape -out and tape -in receptacles, existence - for speed ... set its monitor switch to source or variety and range of cir- input, cuits offered. plug a high-level source (which could be your recorder's preamp outputs) into the JUST OFF PRESS! tuner or aux inputs, and set the source selector appropriately. If you get sound Electronic Circuits Manual now, von may have had the tape recwder by John Markus connections reversed, or you may have a ever 950 pp., 81/2"x11", $19.75 condition whereby the tape output More Than 3,000 Illustrations connections are shorting the signals to For hobbyists . experimenters ... engineers ground. (Some tape recorders, for . technicians. Includes all latest developments in solid-state components...integrated circuitry example, ground their input connection electronic tube designs. First use pays for book when they are set for playback.) many times over. If there is still no sound with this basic 115 new operational amplifier circuits ... 93 system hookup, look for a motor control circuits . 39 lamp dimmer cir- burned -out tube cuits ... 56 automotive circuits ... 23 optoelec- (if you have any in the system) or resign tronic circuits 64 counter circuits-and ... over yourself to the possibility of a power 2,000 more! supply repair. Special Features If your preamp 99 chapters.group similar circuits for easy and power amplifier comparison are separately powered, a further check Complete data on all component values will show which of these is the offender. Concise descriptions of significant circuit features, performance and operating data, Unplug one cable from its preamp output and source citations receptacle and touch its bared tip with Circuits arranged for quick, accurate eval- your finger. If you uation of advantages and drawbacks get hum, the power Many outstanding designs from other amplifier is OK and the preamp is at countries fault. No hum. and the power amplifier is -Partial Contents: Audio Control Circuits... Auto- the troublemaker. motive Control & Ignition Circuits . .. Code Cir- cuits ... Flasher Circuits ... Hobby Circuits ... High -voltage Circuits ... Lamp Control & Dim- One Channel Dead. This is the most com- mer Circuits . Metal Detector Circuits . . . mon malfunction in systems that "used to Power Supply Protection Circuits . Tachom- eter Circuits . . . Telephone Circuits . . . and work fine," and one that can tax the many, many more! patience and ingenuity of any audiophile, particularly when the system happens to 10 -Day Free Trial -Order Today! be a fairly complex one with all sorts of -on McGraw-Hill Book Company hang accessories and a hopeless tangle of identical -looking interconnecting cables. 1 330 W. 42nd St., N.Y., N.Y. 10036 1 Please send me Electronic Circuits Manual You can generalize about such a condition, (040444-5) for 10 days on approval. At the end though, with the thought that, if you 1 of that time I will remit S19.75 plus local tax, 1 postage, and handling or return the book and routinely (or even occasionally) change 1 owe nothing. (This order subject to acceptance 1 by McGraw-Hill.) connections, the trouble is probably a airing error. Otherwise it is probably a 1 Name malfunctioning component. In either event, i Address 1 a simple process of elimination will pinpoint City the 1 1 source of the problem. State Zip Wiring errors generally stem from lack Offer góod only in the U.S. 23 -PE -272 1 of identification of interconnecting cables. 1 1.: Unless they are color coded or tagged at ' CIRCLE NO. 29 ON READER SERVICE CARD both ends, it is easy to pick up one end

12 POPULAR ELECTRONICS Including Electronic: World ELECTRONICS Igtranthanl School of enginrering TECHNICIANS: Mr tenleree en 3.ot)n Ooe

tie orerer al If you really want Rssoriatr in Sciatic to go places.in this Age of Electronics... EARN YOUR DEGREE

Where will you be five years from today? Still The Grantham Educational Program working in a dead-end technician job, OR hold- The Grantham electronics engineering program ing down a comfortable engineering position? is presented in lessons that have been prepared The will deci- answer be determined largely by with great care by expert teachers. The.lessons sions you make now. You can become anelec- place heavy stress on fundamental concepts of Ironics engineer, mainly by logic and mathematics. rather than on superficial STUDYING AT HOME manipulative skills. Since these fundamental ideas are largely unfamiliar to technicians, it is The Grantham college -level home -study program necessary to develop them in a systematic man- is presented at the same level as resident college ner. This is done in the Grantham lessons. engineering courses. However, the lesson mate- The Grantham program for the Associate in Sci- rials are prepared in greater detail and with ence Degree consists of 400 correspondence les- greater care than is normally the case in resident sons, followed by a two-week residential seminar schools. We teach you step by step: emphasis is at the School. on understanding rather than memorizing. Accreditation & G.I. Bill Approval Engineers Will Be Needed - Prepare Now Grantham School of Engineering is a college - level correspondence institution, authorized As you know, during the past two years there has under the laws of the State of California to grant been an oversupply of engineers. Now, probably academic degrees. The School is approved under as a result of that condition, the percentage of the G.I. Bill, is accredited by the Accrediting college students going into engineering has Commission of the National Home Study Coun- decreased by approximately 40%. Also. now the cil, and is an eligible institution under the Fed- demand for engineers is again increasing and is erally Insured Student Loan Program. expected to continue to increase during the fore- seeable future. The situation is developing in such For complete details, mail postcard or coupon. a manner that forecasters see a great shortage of PE -2-72 engineers in the Seventies. Grantham School of Engineering 1505 N. Western Ave., Hollywood, Calif. 90027 You can't become an engineer in a few short Please send me your free Bulletin which explains how weeks: it takes many months. Therefore. now is the Grantham educational program can prepare me for the time to get started-to begin studying-in. a degree in electronics. preparation for the greater demand in engineer- [l I am a beginner In electronics. I] I have a little experience witfi electronic equipment. ing that is sure to come. I am an experienced electronics technician.

Grantham School of Engineering Name Established in 1951 Address 1505 N. Western Ave. City State Zip Hollywood, Calif. 90027 J CIRCLE NO. 22 ON READER SERVICE CARD

FEBRUARY 1972 13 of a cable and trace it back to the wrong socket. So the recorder's input cable may go CUSTOM TAPE to the preamp's tape -out receptacle or the preamp's F\[ input gets the other end of the cable that goes to its auxiliary input. COMPONENTS1 The long-range answer to this problem is to mark your cables properly at both ends- either with identically colored splotches of paint (sold in little bottles in hobby shops) or with tape or paper labels. With the {' ` ..f latter, you can use a ballpoint pen to .. write such things as "preamp tape out left" and "recorder in left" at opposite ends of V.5. the cable. You can also use a more flexible system composed simply of numbers with one cable having 3L at both ends Model 87. Compact, inexpensive, yet highly and its mate having 3R at- both reliable ends. Then two speed, two motor open reel tape no matter how tangled transport ideally suited for most manual record- your cables get, ing/playback applications. Interlocked tape von can always make sure that- what comes motion and record controls, pause and cue out of one component goes into the proper controls. Monaural or stereo head configura- receptacle on another component. On the tions. Available also three motor, electrically controlled series 230 tape transports. other hand, if you have one dead channel in your system now, you may not he immediately concerned with long-range solutions. To locate the trouble, then, first establish whether or not the dead channel is out on one input source only or on all inputs. To do this, simply interc range the input connections from the affected source and note if the malfunction is on one side Broadcast quality transports for all NAB type or the other or if it stays put. If it endless loop tape cartridges. Three models - manual, semi -automatic or automatic for broad- reverses, the trouble affects that source cast, industrial or commercial applications. only and is located either in that Single or dual speed, in monaural or stereo head component or in its configurations. interconnections to the preamp. Check to make sure that both interconnecting cables are properly inserted and that the wires coming from that component actually go to their appropriate preamp inputs. Suppose you do have a tangled mess of cab_es behind your preamp? How do you Matching electronics for above. RP 84, pro- know which end of which cable goes fessional solid state, monaural record and playback preamplifier for tape transports with two where? Set the selector to the desired or three heads. Selectable equalization from source, unplug each cable (at the source), 1-7/8 to 15 ips. A -B monitor switch. Mixing of and touch the bared tip with your finger. line and mike inputs. Bias synch provision for If one doesn't cause a hum, either the multi -channel applications. Phone jack, VU meter, record light. 30-18,000 Hz ± 3dB at 7.5 cable is open or it is shorted internally; ips. Also model PB-10 playback preamplifier or you're not touching the end of the and model PA94F, 8 watt playback amplifier. cable you think goes to that preamp input. For free catalog and price information write To find out which one you are touching, switch inputs until PRODUCTS OF SOUND.PESEAPCI+ one responds to your touch with the requisite hum. If you're still no further ahead of the game, tag that TELE cable at the loose end and take the time COMMUNICATIONS Div ISIDN to unravel it from the tangle. It may not 9600 Aldrich Ave. So. Minneapolis, Minn. -55420 be connected to anything. If the CIRCLE NO. 45 ON READER SERVICE CARD interconnections are all OK, then the defect

14 POPULAR ELECTRONICS Including Electronics World PVT IT TO THE

Leave it to B&K to come up with a new model 179 FET/VOM with features that almost make it unbelievable at its price. Complete DC voltage ranges from .3V to 1000V; DC current ranges .03 to 300 mA; AC voltage ranges .3 to 1000V and AC current ranges .03 to 300 mA. Resistaice 0 to 500 Meg and stable cperation 0° to 40°C. Fastest and easiest to use. The 179 uses Field Effect Transistors for drift -free accuracy. High input impedance minimizes circuit loading. And the 179's super -wide variety of ranges makes this an ideal FET/VOM for shop, lab, production line, or school. Includes mirror scale, and stay -put handle. Now is the time to update your shop witt a stable, prctected FET/ VOM. And the economi:al, yet professional B&K 179 is the instrument that will give the ".------t-7:, most usefulness and - . \ satisfac-ion for your ', money.

Ask your distributor or write us for catalog.

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B&K Model 179 FET/VOM $74.95 The new standard of stability CIRCLE NO. 10 ON READER SERVICE CARD

FEBRUARY 1972 15 must be in the pickup or tuner or whatever CAN YOU QUALIFY else is involved. HELP WANTED Go to the Other End. Now, assuming that for a high paying switching inputs did not reverse the & secure positian affected channel, then there is trouble in CIRCUIT as a... the preamp or later in the system. At this point, it is generally best to start at the DESIGNERS CIRCUIT end of the system and work forward. First, check the most obvious things-unplugged plugs and strands of Salary: DESIGNER? speaker cable shorting across their terminals. Then $12,000 to $17,500 interchange the loudspeaker connections at the amplifier, Requirements: swapping them right for left. If Chances the malfunction then BSEE or EQUAL reverses channels, the speakers and their wires are OK and should be are 1J restored to their original ANY COMPANY connections. (Make sure that the ground EVERYWHERE, USA can and zero terminals of each speaker are connected to the corresponding amplifier connections, to maintain DEGREE REQUIREMENT WAIVED! correct phasing.) The need for Circuit Designers is so great that If the same speaker remains dead when employers will put aside the degree requirement the leads are switched, make the same to move up or hire men with these skills. In connection reversal at the speakers. If this there are these every industry men holding causes the dead channel prestigious positions who do not have a degree to switch sides, in engineering. WILY NOT YOU? that speaker cable has a break in it and should be replaced. If the same channel is UP-TO-DATE TRAINING! still dead, scratch one loudspeaker. Open Our programs are not a rehash of the electronics you already know, but intensive training in the circuits in speaker cables and entire speaker electronics you do not know. They offer you systems are rare, but they do happen. "hands-on" learning of how to design circuits (Most lose just woofer or tweeter.) using the latest devices. Included arc: transistors. If you've IC's, PET's, IC power supply regulators. UJ"1"s... exonerated the speakers and plus more. ARE YOU READY FOR TODAY'S their connections, interchange the channels ELECTRONICS? at the next accessible spot ahead of the power amplifier. \Vith a separate amplifier LOW COST! and Because these courses are highly specialized. preamp, do this between them at the you can choose a curriculum which best suits power amplifier, switching left for right. your needs. And, most important, you can (Make this switch with the system turned learn at a price you best afford. YOU can CAN off.) If the dead channel changes AFFORD TO WAIT ANOTHER DAY? sides, the power amplifier is OK and the trouble is ahead of it-either in the preamp or in one Send for litera- iyoT of the interconnecting cables. To ture FoR check FREE! BFci for the latter possibility, try another cable in you can qualify for training the dead channel. as a CIRCUIT DESIGNER. If the trouble appears to be ahead of this point in the system, it is in the The Center For Technical Development, Inc. preamp. (You've already checked out the 517 E. Main St., Louisville, Oh., 44641 input sources.) A common cause of one - PE22 channel loss here is an intermittent tape Gentlemen, please send me complete details on monitor switch, so check this by gently your CIRCUIT DESIGN courses. rocking it back and forth to see if it lets Name Age the missing signal through in any position. If it does, a squirt of contact cleaner may Address give it a new lease on life. If not, or if the monitor switch is evidently not the culprit, Zip then the preamp or the whole amplifier will need the ministrations of a competent CIRCLE NO. 8 ON READER SERVICE CARD service technician. to POPULAR ELECTRONICS Including Electronics World -

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For eight years we've been telling you about the tremendous _ Mark Ten (Assembled) $44.95 advantages of CDI systems. We've promised, and delivered - ppd better performance for cars, boats and trucks. Hundreds of Mark Ten (Deltakit) $29.95 thousands of satisified customers testify to that fact. However - during these eight years, we've been asked -over and over Kit available in 12 volt only, ppd ground again, "If CDI systems are so great, why doesn't Detroit adopt - positive or negative them?" It's taken a long time, but finally Detroit has recognized Mark Ten l3 $59.95 ppd_ the value of the CDI system. Chrysler, long noted for excellence (12 volt negative ground only) in engineering, is now installing CDIs in new cars. Have you -- seen their ads? Heard their commercials? They're repeating Order today! what we'.ve said for eight years. Cat systems not only improve -_ performance, but eliminate the need for most tune-ups. If Dept PE you're not buying a new car, but want new car perfórmance,__ put a Mark Ten or Mark Ten B on your present automobile. If DELTA PRODUCTS, INC. you're purchasing a new car with no CDI system, install a - P.O. Box 1147 / Grand Junction. Colo. 81501 (303) 242-9000 Mark Ten or Mark Ten B and enjoy the benefits of low main- - tenance and increased performance. Please send me literature immediately: HERE'S WHAT A MARK TEN WILL DO FOR YOU: Enclosed is s__ Ship ppd. O Ship C.O.D. Please send: Mark Ten and Mark Ten B-up to 20% increase in gasoline - _Mark Ten B@ $59.95 mileage El Eliminates 3 out of 4 tune-ups Installs in only 10 minutes El Spark plugs last 3 to 10 times longer T] Dra-_ _Standard Mark Ten (Assembled) @ $44.95 matic increase in performance Promotes more complete -- _6 Volt: Neg. Ground Only _Positive Ground Ground combustión Instant starts in all weather. _ _12 Volt: Specify _Negative Standard Mark Ten (Deltakit') @ $29.95 Mark Ten B Improves combustion, reducing contaminants - - (12 Volt Positive Or Negative Ground Only) Handy switch with redundant contacts for instant return to Car Year Make standard ignition Applicable to ANY 12 volt n egativo ground -- Name engine --Eliminates starting and idle problems ºLonger_ Address spark duration during cranking and idling. City/State_ 71p

Superior Products at Sensible Prices_ CIRCLE NO. 14 ON READER SERVICE CARD 10 Reasons why RCA Home Training is your best invest- ens for a rewardin career in electronics:

1711

I- « -. ;vw+''k yo,,

/yt ' Performing transistor experiments i

_ on programmed breadboard-using Z _ oscilloscope a_

18 POPULAR ELECTRONICS Including Electronics World LEADER IN ELECTRONICS SPECIALIZED ADVANCED tution under the Federally Insured Stu- 1 TRAINING 5 TRAINING dent Loan Program. When you think of electronics, you im- For those already working in electronics mediately think of RCA...a name that or with previous training, RCA Insti- RCA INSTITUTES IS FULLY stands for dependability, integrity, and tutes offers advanced courses. You can 10 ACCREDITED pioneering scientific advances. For over start on a higher level without wasting RCA Institutes is an accredited member half a century, RCA Institutes, Inc., a time on work you already know. of the National Home Study Council. subsidiary of RCA, has been a leader in Licensed by N.Y. State-courses of study technical training. PERSONAL SUPERVISION and instructional facilities are approved 6 THROUGHOUT by the State Education Department. RCA AUTOTEXT TEACHES All during your program of home study, 2 ELECTRONICS FASTER, EASIER, your training is supervised by RCA In- ALMOST AUTOMATICALLY stitutes experts who become personally VETERANS: TRAIN Beginner or refresher, AUTOTEXT, involved in your efforts and help you RCA Institutes' own method of pro- over any"rough spots" that may develop. UNDER NEW GI BILL grammed Home Training will help you learn electronics more quickly and with HANDS-ON TRAINING SEND ATTACHED POSTAGE PAID CARD less effort, even if you've had trouble 7 To give practical application to TODAY! FREE DESCRIPTIVE BOOK with conventional learning methods in your studies, a variety of valuable RCA YOURS WITHOUT OBLIGATION! the past. Institutes engineered kits are included in your program. You get over 250 proj- If reply card is detached, send this coupon WELL PAID JOBS ARE OPEN TO ects and experiments and as many as 22 today. 3 MEN SKILLED IN ELECTRONICS kits in some programs. Each kit is com- RCA Institutes is doing something posi- plete in itself. You never have to take RCA INSTITUTES, INC. apart one piece to build another. They're DEPT. e394-202.0 tive to help men with an interest in elec- 320 W. 31 ST. tronics to qualify for rewarding jobs in yours to keep and use on the job. NEW YORK, N.Y. 10001 this fascinating field. There are chal- Please sand me FREE illustrated career lenging new fields that need electronics FCC LICENSE TRAINING- catalog. I understand that I am under no technicians...new careers such as com- 8 MONEY BACK AGREEMENT obligation. puters, automation, television, space Take RCA's Communications Career electronics where the work is interest- program-or enter with advanced standing and earnings are greater. ing and prepare immediately for your Name 1st, 2nd, or 3rd class FCC Radio Tele- WIDE CHOICE OF CAREER phone License examinations. RCA In- Address 4 PROGRAMS stitutes money -hack agreement assures Start today on the electronics career of you of your money hack if you fail to City your choice. On the attached card is a pass the FCC examination taken within list of "Career Programs", each of which 6 months after completing the course. State ZIP starts with the amazing AUTOTEXT method of programmed instruction. CONVENIENT PAYMENT PLANS Age Look the list over, pick the one best 9 You get a selection of low-cost tui- Veterans: Check here suited to you and check it off on the tion plans. And, we are an eligible insti- card. nd'

Construction of Multimeter. Temperature experiment with tránsistors.

a t tj t o t , , , 1 . n , , , ) + i ' r I'

Construction of Oscilloscope.

FEBRUARY 1972 21 n..

: -9

i -

Four channel sound means` four speakers in one room... It's no problem when they look like these... Empire's world-famous speaker systems fit everywhere and reproduce everything. They thrill you to the kind of sound no box -type speaker can deliver. to Empire's stereo cylinder, the woofer faces down for bass so live it gives you goosebumps. There is no ugly grill cloth, the handsome finish goes all the way around, and the marble top is meant to be used. Available in satin walnut or antique oak finish. Priced from $109.95. For information and further details, write Empire Scientific Corp., 1055 Stewart Ave., N.Y. 11530. Garden City, erfl ire_) NION IIOfU11 Mfd. U.S.A.

CIRCLE NO. 20 ON READER SERVICE CARD

22 POPULAR ELECTRONICS Including Electronics World .S . News Highlights 4 ,,;1,,;1_4.3' ,1

RCA Records Comes Out for Discrete 4 -Channel Disc At a recent press conference, RCA Records carne out strongly for the discrete 9 -channel disc pioneered by the Victor Company of Japan (JVC) rather than for any of the matrix methods that have been proposed. They described the matrix method as offering "the compromise of electronically processed sound which only simulates a 4 -channel effect." RCA gave a progress report in which they reported that the disc could become a marketable reality in the not -distant future, after the mechanical compatibility problems have been completely solved. Because of the very high frequencies on the disc (up to about 50,000 Hz), record wear and cartridge design have been problems but these are both headed for solution, according to RCA. The idea is to produce a single record for each release that would be playable on discrete 4 -channel or stereo equipment so that the record dealer will have but a single inventory. Playback equipment from JVC and Pana- sonic were also demonstrated. This equipment is expected to he available in a matter of months when the 4 -channel records hit the market.

Broadcasters and CATV Operators Agree on Rules A compromise agreement between TV broadcasters and CATV operators should pave the way for future growth of cable TV. Cable companies will be allowed to offer two out-of-town broadcasts to big - city viewers in addition to all the local channels and the operator's own programs. In the 50 largest -market cities, copyright restrictions will limit imported programs to those for which local broadcasters have not already bought exclusive rights. Also, some form of compensation to film copyright owners will have to be negotiated by the CATV operators. The FCC is expected to issue new rules shortly based on the compromise agreement which has been worked out.

Sony Plans Color -TV Plant in U.S. Sony Corporation announced recently that it is planning to construct a facility in suburban San Diego, Calif. to assemble color television sets. Operations are scheduled to begin in May of this year. Although the initial production target of the new plant will be 5000 Trinitron color television sets per month, it will have a potential capacity of assembling up to 20,000 sets per month. Time plant will be about 140,- 000 square feet in area and will be constructed in a manner to allow for future expansion. It will be owned and operated by Sony's wholly owned subsidiary, Sony Corporation of America.

Laser Recorder for Business Machines What is claimed to be the first practical laser recorder for use with business machines has been developed by Datalight, Inc. of Bloom- field, Conn. The system, named "Datawrite," uses a low -power laser to write directly on dry process recording media, and therefore produces instantaneous copy. High-speed performance is made pos -

FEBRUARY 1972 23 sible by the use of acousto-optic laser deflection and modulation. This technique uses the interaction of high -frequency acoustic waves with the laser beam in a solid medium to control laser brightness and direction. The system writes alphanumerics, graphics or digital words from computer data at speeds consistent with the fastest digital equipment. Applications include phototypesetters, non -impact printers, digital storage systems and displays.

Holography Inventor Awarded Nobel Prize Dr. Dennis Gabor, staff scientist for CBS Laboratories, has been awarded the 1971 Nobel Prize for Physics for his invention of holography. Dr. Gabor invented the lensless photographic technique of producing three-dimensional images by light -wave interference patterns some 23 years ago. But it was not until the laser emerged much later that practical holographical techniques became possible. Holog- raphy has since become a tool for use in industry, science and government, and has found practical applications in such areas as color television and medicine. Dr. Gabor worked out the mathematical basis for holography when he discovered how to reconstruct images of objects from the light -wave interference patterns. He used this interference principle to construct the first hologram in 1948, which he named after the Greek word "holos" meaning whole.

Teleprompter Guilty of Bribery The Teleprompter Corporation and its board chairman, Irving B. Kahn, were found guilty in New York Federal Court of bribing city officials to obtain a CATV franchise in Johnstown, Pa. Two of the officials involved, the former mayor and city councilman, pleaded guilty to a conspiracy charge at the start of the trial and testified for the prosecution. Lawyers for the Teleprompter Corp. stated that the corporation and its board chairman were victims of economic extortion by the officials in return for an exclusive cable television franchise.

Thermal Duplication of Video Tape DuPont Co. has been granted a U.S. patent on its thermal method for duplication of chromium dioxide magnetic tape. The process, known as thermoremanent duplication, is based on the particular magnetic properties of chromium dioxide, used in the company's Crolyn magnetic tape. The process can duplicate video tape at least 10 to 15 times faster than present electronic methods without loss of quality. Application of the technology should play an important role in the growth of the large consumer market predicted for pre-recorded video cassettes. Sony, Philips, Memorex, Ampex and BASF are companies which hold licenses from DuPont to make, use and sell chromium -dioxide -based magnetic tape products. In addition, the company itself supplies video and audio wide tape stock or finished tape.

Superscope Acquires Japanese Stock In what is said to be the first time in the history of Japan, the Jap- anese government has permitted a foreign corporation to obtain 50 percent of a publicly listed Japanese company. The foreign corporation in this case is Superscope, Inc. and the Japanese company is Standard Radio Corp. Under the terms of the agreement, Superscope has acquired 5,600,000 shares of Standard's capital stock for an undis- closed sum. Standard Radio has been associated with Superscope as supplier of moderate priced Marantz products, manufactured by Stan- dard to Marantz engineering specifications. Marantz is a subsidiary of Superscope, Inc.

24 POPULAR ELECTRONICS Including Electronics World Ecstasy. At a price that won't cause too much agony.

Before the ecstasy of listening to your new stereo or to let you bust your buttons bragging about .it. equipment comes, alas, the agony of shopping for The tuner, though, makes no concessions: It has it-the frustration of wanting this feature, and a sensitive, overload -proof FET front end. And that spec, and finding that your budget won't ceramic i.f, filters that increase selectivity and quite cover it. never need realignment. Plus a tuning meter for Sony has something to ease the pain. The STR- both AM and FM. 6036. An FM Stereo/AM-FM receiver for the man The controls have all the flexibility you'd expect with a small room, a small budget, but big ears from Sony: tape monitor, main/remote speaker nonetheless. selector, switchable loudness, even front -panel It's an inexpensive receiver that doesn't sacri- microphone input jacks. fice performance, specifications, control flexibil- And the control feel is typical Sony, too - firm, ity. sound quality, or even looks. silky -smooth and positive. So the pleasure begins What it does sacrifice, of course. is just a bit of at your fingertips, even before your ears can start power. The STR-6036 .de- enjoying. Your pleasure livers 50 clean watts of ..- -f-- -- , 4. will deepen to ecstasy when IHF dynamic power at 4 you hear the low price. As ohms*. That's quite enough i _ will your dealer's when to drive even most low-effi- you buy one. Sony Corpo- ciency"bookshelf"speakers, I - , . 17 ration of America, 47-47 even if it's not enough to i ;` 00 Van Dam Street, Long rival the power company, Island City, N.Y. 11101. IHF standard constant supply method. The SONY. 6036 Stereo Receiver

CIRCLE NO. 41 ON READER SERVICE CARD

FEBRUARY 1972 25 people relaxed and quit worrying PAOST'YA about fallout and the "bomb" nearly a decade ago. The Limited Test Ban Treaty (June 1963) ended atmospheric testing of nuclear weapons. Only Red China and France have exploded bombs since then with predictable radio -ac li\ e clouds waft- ing across continent and ocean. In spite of the "now" issues, the spectre of harm from nuclear radiation is still with us. Tests of nuclear explosives continue, although most are performed underground. Nuclear power plants dot the nation. The result is that chances of radiation pollution keep mounting. Some scientific authorities say that we relaxed under false assurances. The Atomic Energy Commission keeps telling us that none of today's uses of nuclear energy present any significant danger. Yet, the evidence keeps piling up that potential radiation danger lurks in peaceful uses of nuclear power. \Ve have accumulated more knowledge of the Iliroshima/Nagasaki survivors and their descendants. Some genetic consequences were already acknowledged. We know now that even the grandchildren of the survivors are affected. Abnormalities include birth defects, stillbirths, and heredity - related diseases. Lately, cancers began appearing in the bomb victims themselves, and at a rate greater than the national average for all of Japan. And the incidence of the disease is roughly proportional to the amount of radiation the survivors received during the five-year period following the bombings. Accelerated aging is noticeable in some victims who were exposed to fallout when they were very young. Consequences like these, turning up so long after exposure, require that we re- evaluate our thinking. \Vhat illnesses will workers near radioactivity contract? \Vhat effects will they have on their offspring in the future.

Electronics helps monitor and control contamination you can't see, hear, taste, smell, or feel

BY FOREST H. BELT

26 POPULAR ELECTRONICS Including Electronics World Proponents of more nuclear power put forth a threshold theory which assumes Editor's Note: There are many bene- that there is some small radiation dosage fits to be derived from the peaceful use below which effects are zero. This concept of nuclear energy, especially in the fields is based mainly on the lack of any immedi- of power generation and medicine. Al- ate symptoms when the radiation close is though this article points out the dangers very low. But evidence gathers for the involved, we can take advantage of the minimize the hazards by z theory; that radiation -related dis- benefits and linear other aberrations increase in enlisting the aid of electronics and eases and genetic safeguards in control and monitoring. proportion to the radiation one accumulates, Those involved with the applications of even to the most minute dosage. This means nuclear energy are well aware of the that .radiation might have a cumulative problems in working with such a potent effect. It is possible then that future gener- force. Hence, safe operating practices ations well may carry the burden of any are observed to keep all hazards to an radiation carelessnesses now. absolute minimum.

Radioactive Materials. If neutrons forced out of atoms as a result of nuclear reaction reac i the air, they can mix with nitrogen for more than 25 years. This is an open in- atoms and form carbon-14. This radioactive vitation to leukemia aid cancer. nuclide has an extremely long life and can The isotope cesium -137 also goes to be very dangerous to man. Obviously, then, muscles and bones. Beta and gamma rays in employing nuclear reactors for peacetime from it endure beyond the nuclide's 33 - applications, neutron escapes must be pre- year halflife. (NOTE: Radionuclides are vented. considered to be ineffective after half their The decay of uranium -235 also forms atoms have decayed, although some of variants called isotopes. If the isotopes get their rays remain potent for a longer time.) out of a reactor, they can carry radiation Gamma rays are intensely more penetrating to us in various ways, mainly by concentrat- than are beta rays. They can destroy body ing in our food and water. cells from relatively great distances. Strontium -90, for example, settles to Iodine -1.31 gathers in thyroid and salivary earth where grass absorbs and concentrates glands. This isotope has a half-life of only it in its blades. Cows grazing on the con- eight days, but gamma and beta rays from taminated grass increase the concentration it are energetic. They damage sensitive in their milk. Anyone who drinks the milk throat cells and trigger thyroid cancer. gets a hefty close of the beta rays given off Plutonium -239 is the most hazardous by- by the isotope. Other nuclides collect in product of uranium -235 fission. Its halflife other foods, animals and fish. Many of these is 24,100 years. It is a deadly source of nuclides, in addition to giving off beta rays, alpha and gamma rays that tire so powerful are contaminated with alpha or gamma that they still produce lung cancers when radiation. the isotope has aged 200,000 years! Ex- Beta radiation is not strong. Skin, muscle, posure to fresh plutonium -239, even briefly, and other tissue help to block it when the multiplies cancer susceptibility a thousand- body is externally exposed. Taken intern- fold. ally, however, strontium -90 settles in bone Ionizing radiation produced by atomic and muscle where beta rays freely emanate decay attacks body cells. Radioactive par-

NUCLEAR RABIA TIO ...INSIDIOUS POLLUTER

FEBRUARY 1972 27 tides rip electrons out of atoms in cells. in the air, soil, and buildings. And about 25 Sometimes the shock kills the cell, some- mr comes from inside our bodies. We ingest times it merely fouls up operation. Damag- through breathing, eating, and drinking ing a body cell sets the stage for cancer traces of thorium, potassium -40, carbon-14, and other diseases. Chromosome damage in and tritium; and there is no way to avoid the reproductive cells leaves consequences them. that may linger for generations. Whenever we have an X-ray picture Some cell damage self heals. Some dam- taken, we get a dose of radiation. The age is irreparable. The body often replaces younger we are, the more damage X-radia- dead cells, which leads some experts to tion is likely to cause. A study by Dr. Alice contend that there is a threshold level below Stewart of Great Britain-confirmed by Dr. which radiation will do no somatic or ge- Brian MacMahon of Harvard-relates X- netic damage. True, below certain levels no rays during pregnancy to a rise of cancer immediate clinical symptoms appear, but and leukemia in children age 10 years and radiation doses accumulate and eventually younger. produce effects that are noticeable. X-rays are, nevertheless, beneficial diagnostic tools in medicine. The American Typical Radiation Doses. We cannot see, College of Radiology, however, advocates hear, taste, or feel radiation, but it is always reduction of per -photo dosage; this will around us. We get yearly background dos- help. X-rays, cobalt -60, and other radio- ages of about 125 millirads-more if we live active isotopes also have high therapeutic at high altitudes. (A rad is a measure of value. But in spite of their obvious bene- radiation standing for Radiation Absorbed ficial qualities, they remain sources of haz- Dase and is roughly equal to a Roentgen, ardous radiation. or rem, which is a technical unit of radia- Safety guidelines have been set up by tion. The rad is abbreviated as the letter the Atomic Energy Commission, with aid provided by the Federal Radiation Council, An average of 50 mr of annual back- the National Committee on Radiation Pro- ground dosage is due to cosmic radiation tection and Measurement, and the Inter- from high-energy protons originating in national Commission on Radiological Pro- outer space. Another 50 mr or so comes tection. The guideline doses are represented from potassium -40, thorium, and uranium as "safe" exposures. But in light of recent data and experience, some scientists in the Two -layer plastic radiation suits reduce nuclear and health fields dispute their exposure danger for workers entering safety. contaminated area. Umbilical tube car- The guidelines suggest that the average air and communication ries fresh for the popu_ation at large be less wiring. On leaving area, worker simply dosage shucks the outer suit. (Photo: US Atom- than 170 mr/yr, not counting natural back- ic Energy Comm. Richland Operation) ground radiation. Any one person should receive no more than 500 mr/yr, say the guidelines. Individuals in radiation -associated jobs are permitted an "acceptable" dosage of 5000 mr/yr-40 times the background level. Medical Physicists John W. Gofman and Arthur R. Tamplin of the Lawrence Radi- ation Laboratory in California make a strong case that even 170 mr/yr can induce an extra 32,000 cancer (plus leukemia) cases annually, representing a 10 percent rise over the usual average. Also, genetic effects might add 150,000 deaths and even more deformities and diseases. Naturally, nuclear industries take elaborate precautions to maintain exposure below the AEC maximum. Shielding and special suits are used to block nuclear rays. Remote control handling keeps operators away from

POPULAR ELECTRONICS Including Electronics World critical materials. Instruments monitor radi- FRAGMENT ation levels where contamination might NUCLEUS i exist or develop. Some cities, like New v0 MORE FISSION -- FREE York, monitor nuclear radiation level con- FRAGMENT NEU TNONS _ stantly. Film badges check the daily and NUCLEUS/". 411F RAGMEN TS weekly rad dosages of workers who risk FREE NEUTRONS exposure. But for the ordinary citizen, the NEUTRON only real safety lies in prevention. NUCLEUS,' -A MORE FISSION ---.p FREE FRAGMENT Fission vs Fusion Power. There is cur- NEUTRONS rently a big controversy raging with reference to nuclear -electric power plants. The '1» plants may look clean and harmless, but Nuclear fission occurs when a high- their reactors are sources of radioactive dis- speed neutron splits nucleus of ura- charges into the surrounding environment. nium or plutonium. Tremendous energy There is also the possibility that accidents is released and other neutrons are caused by man or nature (freak tornadoes, knocked loose. If released energy is floods, earthquakes, etc.) could spread sufficient, chain reaction can occur. radiation for miles. Hauling and storing nuclear leftovers that can be fissioned into other reactors. also present pollution hazards. This partic- But plutonium is formidable to store and ular problem worries Kansans around the transport. Lyons salt mines where nuclear waste is Fusion, the thermonuclear reaction used being dumped. And there are dangers near in the hydrogen bomb, offers an alternative. plants where reactor fuels are processed. Its deuterium fuel, a heavy isotope of hy- Many worried citizens want no more drogen, is abundant and relatively inex- nuclear power plants built unless they re- pensive. A little generates a lot of power, lease no contaminants at all. California, and known accessible reserves could last Oregon, Minnesota, and New York City us 50,000 years. But most promising, for have even legislated moratoriums that are equivalent energy released, a fusion reaction still in the courts. produces about a million times less radio- Meanwhile, power companies state that activity than does a fission reaction. we must convert to nuclear power because The problem is that fusion reaction is we have enough fossil fuel to carry us not easy to produce or control. We have through only 200 more years. This is a poor machines that can take care of both jobs on argument considering that we have only 75 a limited basis, but none is ready for com- years' worth of uranium at our present rate mercial exploitation, nor are they likely to of consumption. be for a decade or more. Fast-breeder reactors can develop large The chief radiation danger from fusion quantities of a plutonium -239 byproduct is high-energy neutrons. As already stated,

Nuclear test blast in Nevada near Los Alamos lab had nearby tower that held electronic instruments to measure seismic shock, radiation, etc. (Photo Los Alamos Scientific Lab) t _'-

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..- .. , ~ , , ....1 . 0.1 ...R . o O. . W.I w -. : _ :i:-ir-i.?';.. +:. rez.lra--.+FT9k o . . - neutrons form carbon-14 in air. Also, neu- A Growing Tide. We still test nuclear trons wear out the protective vanadium weapons in spite of the April 1970 Treaty alloys used in reactors. on Nonproliferation of Nuclear Weapons Tritium, produced within the reactor, and our present Strategic Arms Limitation has a halflife of 12.5 years and emits strong Talks. Controversial underground tests con- beta rays. So, it must be kept from continue in Colorado and Nevada. And, in taminating air or water. early November, a giant 5 -megaton thermo- A deuterium -helium thermonuclear re- nuclear device for our anti -ballistic mis- action can make electricity directly. The siles was tested a mile beneath the ground method is being worked out at the Law- on Amchitka Island. Neither earthquakes rence Radiation Laboratory. A plasma is nor tidal waves were triggered and the confined in a straight tube called a "mag- AEC states that no radiation escaped into netic mirror machine." The reaction spews the atmosphere. electrons out of the tube into an expansion Missile submarines such as the USS chamber. Collector electrodes gather posi- George Washington and ships like the car- tive charges and a charge separator picks rier USS Enterprise carry fusion reactors up the electrons. Output terminals feed the for propulsion. No reactor is entirely "clean": direct current to whatever load is provided. so, only "safe" doses of radiation reach the Fusion reaction is a relatively "clean" men who run our nuclear fleet. method of generating power, but mechan- The National Aeronautics and Space Ad- ical problems in employing it on a universal ministration has a nuclear -powered rocket scale are still far from resolved. Conse- called NERVA (Nuclear Engine for Rocket quently, we are stuck with fission reactors Vehicle Application). Nuclear propulsion to produce energy; so, we are also stuck could considerably shorten trip time be- with the dangers they present-unless legis- tween earth and. moon. Astronauts already lation eliminates the use of nuclear power get nearly 1000 mr of radiation exposure on plants altogether. an Apollo trip, mostly from traversing the

Articulated mechanical arms and hands let chemist work with radiopharmaceuticals in safety behind concrete wall and sheets of heavily leaded glass. (Photo: USAEC) ... >-

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_f st,: 30 POPULAR ELECTRONICS Including Electronics World fields also Hopped; the blasts left too much tritium in the oil output. The most exciting excavation proposal to date is the large sea- evel canal to be cut across Central America to replace the soon - outmoded Panama Canal. Then nonuclear blasts appear to be the only economical means for such difficult digging chores-but not without problems. Nuclear tests have been detonated above- ground very little since 1963. Engineers are not sure how to deploy the explosives wwf to achieve the desired results. Seismic shock could tear up nearby towns, and the acoustic shock wave has its own dangers. But worse still is the fact that scientists simply cannot produce a radiation -free nuclear ex- f plosion. The cleanest fusion explosives still (1111111) neutrons and tritium into the atmosphere. The new canal is therefore stymied. So are other excavation projects. Truly sale peacetime nuclear technology awaits fission Emergency radiation team members at or f l ision that does not cause radiation AEC's Hanford Works show how Geiger pollution. 0 and scintillation counters are used to measure radioactive contamination Portable radiological survey instru- should it get out of control of users ments built by private of radioactive isotopes. industry for (Photo: Hanford Oak Ridge National Laboratory. Oregon, Atomic Products Operation) Indi- vidual meters are for neutrons, beta and gamma rays, and alpha particles. (Photo: Oak Ridge National Laboratory) Van Allen radiation belts. A quicker trip through the belts may balance out the effects of radiation from the engine. A new nuclear -electric rocket develops onh a few pounds of thrust. However. it operates continuously o'er a long period of time; so, deep -space vehicles could build up extreme velocities over the long haul. Sys- tems for Nuclear Auxiliary Power, or SNAP, thermoelectric generators already snake electricity for scientific experiments on the moon. Larger versions might serve earth needs. Our SNAP-27 uses plutonium -239, but scientists are working on safer versions.

The Big Ditch. Massive nuclear explosives offer engineering promise. But radiation problems hamper the use of such power. A detonation in 1967, called "Gasbugg)," attempted to boost gas output of a \\ ell in New Mexico. Rulison, a similar project in Colorado, took place in 1969. Unfortunately, the gas released is dangerous: no matter whether fission or fusion explosives were used, tritium or krypton -85 in the gas ex- poses customers to radiation. Decontamina- tion is too costly or impossible. Tests in oil

FEBRUARY 1972 31 PRECISION LAB POWER SUPPLY

BUILD THIS REGULATED SUPPLY WHICH DELIVERS UP TO 30V AND 1.2A

BY C. R. BALL, JR.

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t.e POWER Supply

electronics hobbyist and service The power supply described here meets EVERYtechnician needs a bench power supply. these requirements. Its output is 0-30 volts To obtain best results, the supply should be with a line or load regulation of 0.02% or completely variable from zero to the max- 1 mV; 0-1.2. A with line or load regulation imum voltage used in semiconductor circuits of 0.2% or 1 mA. Transient recovery time is (usually 30 volts), and be capable of deliver- less than 25 microseconds, and ripple and ing enough current to carry normal loads noise are less than 0.25 millivolts rms. Cost

(at least 1 ampere) . In addition, the supply is less than $80. should have excellent regulation (both with power -line variations and load changes), Theory of Operation. The complete minimum ripple and noise, automatic cur- schematic of the power supply is shown rent limiting, and provisions for avoiding in Fig. 1. Ilowever, its operation can he damage in case of inadvertant shorts. better understood by referring to the block

32 POPULAR ELECTRONICS Including Electronics World MI 0-ImA

D7 A14F R8 .38f1

R9 470(1 o I SI V

T D 5* CURRENT R6A R6B o R3 500(1 50R I0K COARSE FINE V 0 O + RIO RI 2 FI -TC3 n 8.55K 35K 2.2K IA 800yF R5 1.2K C7 .12 A14F 10 pF GND o C6 C9 C4 240pF .02pF INF 9V RII 05A 1CI o 2.2K I.IyF I150yF D6# J3 S2 o D8 AI4F *1N4001

I17VAC VOLTAGE RIA RIB 30K 1( COARSE FINE D4#

500yF C5 .475F T6

Fig. 1. The use of a recently developed integrated circuit gives the supply its excellent electrical characteristics. The circled letters indicate the connections to the board if you decide to duplicate prototype.

PARTS LIST R5 -1200 -ohm, 1/2 -watt 10% resistor CI -150-µF, 50 -volt electrolytic capacitor R6-Dual concentric control, 500-50 ohms C2, C4 -0.1-µF, 50 -volt disc capacitor R7 -1000 -ohm, 1/2 -watt 10% resistor C3 -2800-µF, 50 -volt electrolytic capacitor R8 -O.38 -ohm, 10 -watt 5% resistor D5 -0.47-µF, 50 -volt Mylar capacitor R9-470-ohm,1/-watt 1% resistor C6-240-pF, 500 -volt polystyrene capacitor R10 -35,000 -ohm, 1/2 -watt I% resistor C7-10-pF, 500 -volt, polystyrene capacitor RI!, R12 -2200 -ohm, 1/2 -watt 10% resistor C8 -500-µF, 50 -volt electrolytic capacitor RECTI-Bridge rectifier (Varo VS2481 C9 -0.02-µF, 600 -volt disc capacitor Si, S2-Dpdt switch Dl, 1)7, D8-A14F silicon rectifier diode (GE) T!-Power transformer; secondaries: 32V at D2 -D6 -1N4001 diode l.2A and 19V at 0.05A F1 -1A slow -blow fuse and holder Misc.-Suitable chassis, heat sink (Delco ICI-Integrated circuit. (Beco 670-003) 728135.3), power transistor mounting hard- J1-J3-Five-wattt binding post ware and insulator, silicone grease, capaci- M1-0-1-mA meter (requires scale modifica- tor mounting bracket, edge connector tion) (Ampheno! 143-010-03), three -wire line Ql-Transistor (Motorola..L1 PS6.531 or cord, wire, solder, etc. HEP736) Note-The following are available from Beet) Q2-Transistor (Motorola /YI1E3055 or Solid State Systems, P.O. Box 686, Salem, 11 EPS5001) VA 241.5.3: two PC boards (PS30A) at R1-Dual concentric control, 30,000-3000 $4.95; 1C1 (670-003) at 311.50; meter with ohms special scale (650-004) at $8.50; transfor- R2 -8550 -ohm, 1/2 -watt 1% metal film resis- mer (101-050) at $9.70; complete kit of tor parts including all hardware, nameplates, R3, R4 -10,000 -ohm, 1/2 -watt 5% resistor wire harness, etc. (PS.30K) at $78.40.

FEBRUARY 1972 33 SERIES R8 (Re) PASS (+) JI ELEMENT C3 OZ J0 - I O(-)J3 SOURCE FI CURRENT

VOLTAGE CONTROL L / OI OUTPUT AMP. DI TII CI--jTI REFERENCE CCA

T L

R6 Fig. 2. In CURRENT this block diagram CONTROL of the supply, all of the func- VCA ICI I tions enclosed by the dashed lines are contained within the IC. -J diagram in Fig. 2. The ac power is applied to transformer Ti, one of whose secondaries supplies bridge rectifier RECTI and filter C.3 to provide unregulated de for the overall regulator. The other secondary supplies rectifier D1 and filter Cl to create the do power required by the reference voltage regulator in /C1. There are five functional circuits in /C/. In addition to the reference voltage regulator, they are a constant -current source, a voltage -controlled amplifier (VCA), a current -controlled amplifier (CCA), and an OR gate. Transistor Q1 is an amplifier driven Fig. 3. These are actual size foil patterns of the printed circuit boards. They can be made of 2 -oz. epoxy -glass.

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34 POPULAR ELECTRONICS Including Electronics World by the output of the OR gate; and Q2 is the main series -pass regulator. The reference voltage regulator provides a stable reference voltage for the constant - current portion, against which variations in other parameters are compared. The VCA functions as a voltage -error sensing amplifier. One input to this differential amplifier is connected to the positive output of the supply, which is compared to a reference voltage derived from a known current passing through a variable resistance (the voltage-control potentiometer). The preset resistance of the potentiometer multiplied by the known current flowing through it determines the reference voltage. Since the \ CA tries to maintain the voltage between its two inputs at zero, any difference between it them produces a change in the VCA output, thus causing either an increase or a decrease in the drive to Q2. The CCA operates in a similar fashion, except that its inputs are derived from either side of a current -sensing resistor (Rs). Therefore, any difference bet\ceen the voltage set by the current -control potentiometer and the voltage across Rs causes a change in the output of the CCA to increase or decrease the drive to Q2. The OR gate determines whether the voltage or Fig. 5. Completed boards should look current control sets the output of like these. The two dual potentiomet- the power supply. If either the A CA or CCA ers mount big board to chassis front. calls for a change in drive to 92, then that amplifier is in control. Output amplifier QI provides the necessary gain to drip e Q2. Construction. The power supply can be assembled in almost any manner, but the Fig. 4. This shows how components are "mother -daughter" PC board approach used mounted on the boards. The small one in the prototype represents an easy assembly plugs into edge connector on big one. procedure and also allows for variations in the circuit, if desired. Foil patterns for the R37,4* a -R7- v two boards are shown in Fig. .3. They should 2 ICI be fabricated on -oz epoxy -glass board and joined by a 10 -pin edge connector. D3d4 `c02-" The components are installed on the boards as shown in Fig. 4. The layout of the large board is such that several points

. are provided for the same connection of JIHGFEDCAB some components to allow for variations in size among manufacturers. Observe the JI J2 J3 R6 rl polarities of polarized capacitors and semi- a l yr conductors. Dual potentiometers Rl and R6 A\ J _'a -RI2 RI I. r should be to the board before B mounted close f-'Dc9 soldering since they provide support for the 19V C5 =mo.nr. I (TI) I.RIO front end of the large board. Clip off the B -. 1 excess potentiometer terminal lengths after 02 C CB- soldering. The completed boards are shown

K in Fig. 5. The boards and other components are EDGE CONNECTOR mounted in a suitable chassis as shown in

FEBRUARY 1972 35 the photograph. The heat sink for Q2 is S2 MI SI mounted on the rear apron using thermal insulation (cork, rubber, etc.) between heat sink and metal chassis. When mounting Q2, use generous amounts of silicone grease and the insulator washers provided with the transistor. The photographs show hog' the various controls, the meter, and output jacks are mounted on the front panel. Remember that the two power controls also support the mother board (with spacers and mounting -RECT hardware). The line cord is brought out 11UF f through a grommeted hole in the back of the chassis. The large filter capacitor (C3) is secured in a clamp mounted on the chassis, 02 HEATSINK while the power transformer is mounted This shows the completed supply ex- along the back of the chassis. cept that the small board is not The scale of the meter must be modified plugged into the edge connector so to indicate from zero to 35 volts with each that it doesn't hide other parts. 5 -volt step identified. On the current scale, each 0.2 -ampere step should be marked controls (R6) to about midrange; and ro- from zero to 1.5 amperes. tate the concentric voltage controls (RI), noting that the meter indicates between zero Checkout and Use. Before putting the and approximately 30 volts. Place SI in the supply in operation, recheck all wiring and AMIP position, short the output terminals interconnections. Be especially careful with (JI and 13) and rotate the current controls. Q2, making sure that it is insulated from The output current should vary between the heat sink and chassis and that it is prop- zero and 1.2 amperes. erly connected. Set the current control about midrange. Turn on the power and set SI to the remove the short between J1 and J3 and VOLT position. Set the concentric current connect a 15 -ohm, 30 -watt resistor across the output terminals. Place SI in the VOLT position and slowly turn up the voltage con- PROJECT EVALUATION trol until the meter comes to a stop. Note HIRSCH-HOUCK LABORATORIES this point. typi- both the voltage and current at The ripple was well within specs, transition cally from 135 to 250 microvolts depend- This is called the voltage -current ing on load and output voltage. The line point. Now, increase the voltage and note regulation was excellent, with no per- that the current does not change. (The sys- ceptible change in output from 105 to tern is now in current -regulation mode.) Ro- 125 volts input. (We could detect as tate the voltage control back to the point little as 1 millivolt if it had existed, where the voltage just starts to decrease. since we used a stable reference voltage Then rotate the current control toward to buck out the supply voltage and a maximum and note that the voltage does Triplett VOM on its 0.3 -volt scale as a not change. (The system is now in voltage- null meter.) work Load regulation was not as good as regulation mode.) If all these checks claimed. At 5 volts output, the 0.02% properly, the supply is ready for use. regulation would have corresponded to If you want to limit the current flow in 1 millivolt, a barely detectable level. an external circuit, short 11 and J3 and set We measured a change of 18 millivolts the current control to the desired level. Re- from no load to 1.2 amperes, indicating move the short and connect the supply to a source resistance of 0.015 ohm. Good, the circuit. No matter what happens in the but not as rated. circuit, the maximum current flow will be No measurements were made in the limited. As the voltage is brought up to the the constant - constant -current mode, but he voltage to constant -current transition required value, the circuit current can seemed to occur smoothly and as in- read off the meter. The supply can also be tended. used for constant current by presetting the current and varying the voltage. O

ELECTRONICS Including Electronics World 36 POPULAR CLASS "E" CB OF THE FUTURE? OVERCROWDING ON CB CHANNELS MAY BE A THING OF THE PAST IF THE CLASS "E" CITIZENS RADIO SERVICE IS ESTABLISHED B ACK in 1958, the Federal Communica- is to guide the service in an ordered growth, tions Commission recognized the need foreseeing potential requirements. and the right of individual citizens to have What would it be like to operate on the safety and convenience of personal two- class E CB? First of all, a class E CB sys- way radio. And so, it established our current tem is intended to be-and definitely is-a class D Citizens Radio Service at 27 MHz. short-range system. Range would be 10 to In past years, citizens radio has grown 20 miles mobile -to -base depending upon an- beyond the wildest dreams of those who tenna height, location, etc. At 220 MHz created the service. Somewhere around 1,- communications range is essentially limited 800,000 licenses have been issued with to line of sight. Skip communications and about 900,000 currently active. skip interference would be non-existent in As the number of CB users continues to the class E service. Communications qual- grow, it becomes increasingly clear that ity and range would be very consistent since more channels-beyond the original 23- atmospheric conditions have little effect on are required. It is this very real need that 220 -MHz propagation. Also almost non-ex- had led many individuals and groups to pre- istent on class E would be man-made in- sent countless proposals to the FCC for its terference (often found on class D) caused consideration. by such things as ignition noise, diathermy, Last year (see "Communications," Pop- and other industrial radiations. To summar- ULAR ELECTRONICS, September 1971) , the ize, if you've ever heard a very good police Citizens Radio Section of the Electronic In- communications radio system, class E CB dustries Association recommended the estab- would be very similar in performance. lishment of the class E Citizens Radio Serv- Is class E right around the corner and ice at 220 to 222 MIIz. It should be stressed what will equipment cost? No one can really here that the new proposed class E service answer that question. Too many factors are would be in addition to the present class involved and too many details still require D service. Briefly summarizing the EIA pro- further analysis and discussions by the FCC. posal, the new service would utilize a rela- Best industry estimates put the proposed tively unused portion of the amateur service at least a year away even if immedi- 220 -225 -MHz band, and would provide 80 ate rule making were to take place. It takes new channels. Industry sources indicate that a while to put the machinery together for 80 channels would provide uncrowded op- such a significant step in personal com- eration for a minimum of 2.5 million li- munications. censees. If you're currently considering getting Power output to the antenna would be into CB, take a close look at the present limited to 25W, with special public safety class D service which will admirably serve agencies permitted to license a base station the CB'ers needs for years to come. Equip- at 100 W output to the antenna when ment in the $100 class is quite common in using this band to assist in public conven- Class D. It is estimated that class E equip- ience or necessity for safety. Antenna height ment will be in the $250-$300 range when would he limited to 20 ft above the nearest it is introduced. Manufacturers anticipate man-made structure or natural object with- that it will take two or three years after in 500 yards; or 60 ft above the existing the establishment of class E before unit vol- terrain (whichever is higher). ume will enable cost of radios to drop to The proposal suggests guidelines for the $100 or $150. You may find that class D is specific use of channels for various appli- the low-cost way you'll want to go or per- cations, such as highway communications haps you'll choose to wait for class E. assistance, home -to -vehicle, car -to -car, etc. There's also much talk on the air by people The basic reason for such recommendations who want both! QQ

FEBRUARY 1972 37 :-., 4 SABff_ I ,

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.f We've got over 300 good, steady jobs. Jobs in construction, transportation, communications, computers. Jobs for photographers, printers, truck drivers, teachers, typists, TV cameramen and repairmen. Cooks, electricians, medical aides, meteorologists. Motor and missile maintenance men. Jobs for young men. And young women. Jobs in Europe, Hawaii, Panama, Alaska. And just about any place in the States. We'll train you to do the jobs. Train you well, in good schools, under excellent instructors, with the best equipment obtainable. And you get full pay while you train. You also get unusually good fringe benefits, including a chance to continue your education. In many cases at our expense. In all cases with at least 75% of your tuition paid. And if you qualify we'll give you your choice of training. We'll put it in writing, before you sign up. Today's hilly wants to join you.

Army Opportumnes Die 2eE 2.72 Dept 200, Hampton, Va 233.59 I'd like to know more about the tob.trammg and promotion oppartuntties in today's Army.

Name Dawolbm5 Address

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Education L ELECTRONIC ENGINEERING EXPERTISE AND ARTISTIC TALENT TEAM UP TO GIVE MUSIC AN EXCITING NEW DIMENSION MOST people associate the word "syn- the choices of things to do first are virtually thetic" with "fake" and conjure up infinite in number. Vs'hat is more, while the ideas of inferior versions of the genuine piano is ready to play immediately, the syn- article. Perhaps it is only natural, then, thesizer must first lie prepared to play. The that many people do not consider music proper combination of switches must be synthesizers and their electronically pro- thrown, dials have to be turned, and patch duced sounds a legitimate part of real cords have to be plugged in. Only then will music. Electronic music has, admittedly, the synthesizer condescend to utter a peep. undergone rather gimmicky stages of de- Playing a music synthesizer probably will velopment, but that is all over now. not always be as difficult as it is now. This Today's sophisticated music synthesizers leave their gimmicky predecessors behind and take an important place in the evolu- . tion of legitimate music. Music - #-- synthesizers are especially noted . -411-----+' --di-- -#-- for the variety of sounds they can assemble -di-- -41- -1 or synthesize. A skilled performer can mix together a handful of basic tones to make the instrument mimic familiar sounds, including those of other musical instruments. Some of the sounds may not be very musical in the usual sense. But just how "unmusical" they sound depends upon the performer's artistic talent and the listener's personal tastes. A good performer can make a synthesizer sound like a cathedral organ one moment; . v---' and then by changing some plugs and dials, he can make it sound like someone walking ` . across a gymnasium floor in wet sneakers. .. . Then, of course, there are the unlimited number of unfamiliar sounds-too strange to describe-that are possible with the music A synthesizer.

An Awesome Experience. The neophyte who sits down at a synthesizer console for the first time, is in for an awesome experience. Seeing all those dials, switches. wires, and plugs can make him feel inadequate. new art/technology wedding is still new. The tendency when approaching a synthe- Ilence, it is constantly being improved. But sizer is to equate it with familiar musical even if the mechanical and electrical bugs instruments. And it is this attitude that can are ironed out tomorrow, there will remain defeat a beginner at the outset. a major obstacle: iIow does one write a With a piano, the musician has a choice musical score for an instrument that does of one out of 88 notes to play. IIe can not fit the mold of traditional musical instru- start anywhere and, with one finger, fumble ments? The little black notes that have out a tune. But it is different when he is served musicians fairly well for centuries sitting at a music synthesizer console where cannot begin to manage the task of coin -

AM AND iiGONiIiY 40 POPULAR ELECTRONICS Including Electronics World BY DAVID L. HEISERMAN

municating an electronic sound no one has sizer, then records the next segment. After ever heard before. completing the recording session, playing From a performer's viewpoint, present - the tape straight through gives the impres- clay music synthesizers have two technical sion that the sequences of sounds flow drawbacks. First, most can produce only smoothly from one to the next. At this one particular note at a time. And, second, point, though, the music still sounds like a they can produce only one particular tonal shallow one -finger melody. quality at a time. Unlike a piano player who Just as the tape recorder can take care can play up to ten notes simultaneously, and of pauses for reprogramming the sound. so. run through an entire composition without too, can it make one synthesizer sound like four instruments. By using a four -channel tape recorder, the performer records his basic one -finger melody on the first track. After that, he fills in the other three tracks,

.. 1/11 killItil ii * ' , one at a time, with the desired background, harmony, and rhythm. It is the same old \i trick that can make one singer sound like a quartet. So, the serious composer and solo performer finds that a four -channel tape re- 1 1 \ \II- ''' Ill: \ ¡Bill': ' 4 0 10 corder is just as important as the synthesizer itself. Several groups of accomplished performers, however, have been touring the If ...... ' ...... :: .._.::: country with live synthesizer concerts. By .....'.: ..... using three or four performers and synthe- 03.,_ :r ;::::::::.... Q sizers on stage, one or two of them can be .. playing while the others reprogram and tune their synthesizers to pick up the music when -.¡ '>.'`",--,.-, the others come to the end of a certain segment. "11 sound - From an economic point of view, music 11 synthesizers are very expensive. Professional instruments bear price tags starting at about / 82000. By adding desirable extras and a , good tape recorder, the cost of setting up Portable synthesizer made by ARP a decent studio quickly roils over the 88000 Instruments (Div. of Tonus Inc.) mark. This, combined with the fact that few people have the expertise to handle the synthesizer properly, keeps the systems out of stopping, a synthetic music performer can the hands of the general public. generally play only "one -finger" music and, In spite of the drawbacks inherent in whenever he wants to change the tonal present-day synthesizers, they are exerting a quality of the notes, he must stop the music powerful influence on the evolution of and reprogram the instrument. modern music. As the art and technology of Because of this stopping and starting, a synthetic music progresses, music synthe- tape recorder is a vital part of the synthetic sizers promise to become as popular as the music studio. The performer records a seg- piano. ment of his composition, stops the recorder, patches a new sound into the synthe- How Synthesizers Work. It is the bar - Of IIIGIB8NIG MEG FEBRUARY 1972 41 ranges for the audio tone oscillators run between 2 and 30,000 Hz. BASIC AUDIO INPUTS These oscillators have separate output jacks or selector switches for sinusoidal, RESULTING AUDIO OUTPUT rectangular, sawtooth, and triangular waveforms. The different outputs give the opera- n MIXERS, tor a choice of four basic tonal qualities FILTERS, from oscillator. The sinusoidal wave- AMPLIFIERS, each form produces a pure sound much like that from a tuning fork. Rectangular waveforms produce one basic tone, too; but it sounds rather raspy because the sharp rising and falling edges contain a large number of high frequency harmonics. The sawtooth waveforms have a lot of raspy -sounding harmon- CONTROL AND TRIGGER INPUTS ics only on one edge. Finally, the triangular waveform produces basic notes that have a Basic synthesizer scheme shows audio quality somewhere between that of a sine inputs combined into complex output. wave and a rectangular pulse. Performer controls the final outcome. A performer can change frequency from an audio tone oscillator without stopping monic structure of the sound from a violin the flow of music. Whenever a change is that makes it distinctively recognizable from desired in the basic waveform, however, the sound of a clarinet. In the music syn- the operation must be stopped long enough thesizer, all sounds that emerge begin from to patch in a different waveform or to turn a number of basic tones. By running these a selector switch. tones throng, electronic mixers, filters, and The noise generator produces mixed-up amplifiers, a performer can juggle the har- frequencies that cover the entire audio spec- monic structure of an electrical waveform trum. This "white noise" has a hissing quality. to make it produce just about any kind of By means of filter circuits, all but one narrow sound he chooses. section of the spectrum can be out, Music synthesizers generate three differ- wiped producing a "pink noise." Pink noise sounds ent kinds of electrical signals: audio signals, like static, too; hut it has a dominant fre- control signals, and trigger signals. The audio quency that slices through. It sounds some- signals eventually emerge from the system thing like wind whistling through tree as sounds. Control signals vary the audio branches. The operator has complete control signals to make them change loudness, pitch or quality. The performer can do these Ionic Industries' "Putney" model has things manually, but it is easier and more a joy stick to let the performer con- convenient to let control voltages do the job. trol two different kinds of functions The trigger signals begin and end control at once. Keyboard is also available. sequences according to a preset program. Again, the performer could perform the trigger operations manually, but an electronic trigger circuit does the job better. Most synthesizers get their basic audio tones from a set of tone oscillators and a noise generator. Each of the tone oscillators produces one note at a time, while the noise generator produces a wide range of frequencies at once, the result sounds like pure static. Larger music synthesizers have four or more identical tone oscillator modules in ,41 " them. Each oscillator has a manual control that can be used to adjust the output fre- uuttu. quency. These oscillators also have voltage control inputs to accommodate output frequency control by means of a voltage from some external source. Typical frequency

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The Model Illc synthesizer, made by R. A. Moog, is perhaps the most ver - satile, sophisticated, and well-known system that is on the markey today. over the loudness and dominant frequency patched into any of the voltage -controlled of the pink noise. circuits in the system. After plugging the \Vhile it is possible to vary the frequency output into one of the V -C audio tone and output level of the audio tone signal oscillators, for example, playing up the scale sources manually, it is far more convenient on the keyboard makes the synthesizer pro- to let control signals do most of the work. duce scale -like tores. Depressing the middle - The various kinds of control signal sources C key on the keyboard, however, does not produce voltages that can change the operat- necessarily make the synthesizer produce a ing frequencies of a tone oscillator. And, familiar middle -C note. by feeding the control voltages to special By adjusting a manual control on the voltage -controlled amplifiers, it is also pos- oscillator module, any key on the keyboard sible to vary the loudness of the audio can be made (o produce just about any note signals. desired. If desired, the performer can even Devices that generate the control signals patch t he system so that playing up the include a 4 -octave keyboard, ribbon control- scale on the keyboard makes the synthesizer ler, envelope generator circuit, foot pedal, produce a downward -going scale. and joy stick. Most synthesizers come What is more, the frequency difference equipped with at least one built-in envelope between two adjacent white keys need not generator module, and performers generally be the familiar one -note difference. A con- use at least one keyboard and a ribbon trol on the keyboard lets the performer con lroller. adjust- the frequency differences between The musical keyboard of a synthesizer keys. looks like a short piano keyboard. But the The output of the keyboard can be con- similarity stops at looks. Each key operates nected to circuits other than the audio tone a switch connected to a long resistive voltage oscillators. By patching the keyboard to a divider network. Operating one of the keys mixer or filter module, it is possible to use picks off a voltage from the divider and sends the keyboard to change the harmonic struc- it to a keyboard output jack. The keyboard ture of waveforms generated by other cir- can be set up so that playing up the scale cuits. Or, the keyboard can be used as a makes the keyboard generate stepwise in- stepwise volume control by patching it to creases in output voltage. one of the voltage -controlled amplifiers. This keyboard output voltage can be Thus, the keyboard for a music synthe-

FEBRUARY 7972 43 sizer can perform many different functions. level of a note. Instead of having every new Perhaps it is a case of sentimentalism on the note come on at full volume, for example, a part of musically inclined engineers that a patch cord, run between the envelop gen- synthesizer's keyboard looks like an ordinary erator and one of the V -C amplifiers, can musical keyboard. There is actually no real make the note sweep up in volume. Like- reason why it should not look like a type- wise, a note can be made to decay away writer keyboard-and, in fact, it might be slowly instead of decaying rapidly. By ad- more useful if it did. justing the contour setting on the envelope Another common control device, the rib- generator, a note can be made to sustain bon controller, does about the same kinds of even after the player takes his hands off the jobs as a keyboard. Instead of producing keyboard. stepwise voltage changes, however, it pro- Electronic mixers, audio amplifiers, and duces continuous changes in output voltage. high -quality headphones and loudspeakers A ribbon controller works something like a also play important roles in a music syn- potentiometer, and, by patching its output thesizing system. A performer can make his to a tone oscillator, it can be used to instrument about as complex as his finances produce sweeping, theremin-like tones. will allow. In general, the more add-ons he Optional control devices such as foot buys, the more versatile his instrument be- pedals and joy sticks work about the same comes. In the long run, though, it is actually way as a ribbon controller. A joy stick has the technical and artistic competence of the the added advantage of being a two-dimen- performer-not the complexity of the sys- sional controller. Moving the handle in one tem-that determines the versatility of the direction can vary the output frequency of synthesizer and the quality of the perform- a tone oscillator, while moving it in the other ance. direction changes overall tonal quality. Moving it obliquely, it can produce degrees Synthesizers Vs. Composers. A perform- of both changes simultaneously. er at the console of a professional music Most of the control devices also generate synthesizer has complete control over every a brief trigger signal whenever changes are sound that comes from the system. In made in the control voltage output. Every principle at least, he "plays" the system much time a key is depressed, the keyboard cir- the same way one plays an organ or piano. There is a growing number of electronic music "composers" appearing as construction projects and finished items in a few stores. These devices, costing about $50 for parts and about $30(1 for the finished item, SELECTABLE are close relatives of the synthesizer. OUTPUTS Electronic music composers, however, do SINE not synthesize different harmonic structures. r" Instead. they assemble different tonal pat- J RECTANGLE terns to produce strange sounding and 1._ sometimes pleasing melodies. By adjusting SAWTOOTH SIGNAL dials or switches, they can be made to pro- FROM A CONTROL duce an almost limitless number of different TRIANGLE DEVICE melodies that can run for years without repeating. In a sense, an electronic music In audio tone oscillator, frequency composer works something like a player of the output is adjusted by control piano. Once the user sets the program, the knob or by use of an external signal. instrument takes over all the work of producing the melodies. cuits generate both a control voltage and a Composers occupy an important place in brief trigger voltage. modern elementary music classes, and they These trigger voltages can initiate other are fun to build and use. But an electronic control operations, such as those performed music enthusiast should be aware of the fact by an envelope generator module. The that the versatility of an electronic music envelope generator is capable of producing composer cannot even begin to approach various control waveforms that can be used that of its big brother, the professional music to adjust the attack, decay, and sustain synthesizer. O

44 POPULAR ELECTRONICS Including Electronics World SURFBUILD THE SYNTHESIZER

REPRODUCE Design Analysis. A complete schematic of the Surf Synthesizer is shown in Fig. I, THE SOUND OF but it is convenient to break the unit down BREAKERS into blocks as shown in Fig. 2. There are a noise source; voltage-controlled, low pass AGAINST THE SHORE filter ( VCF); voltage -controlled attenuator (VGA): and random voltage generator. BY JOHN S. SIMONTON, JR. The noise source (Q7) is built around a reverse biased pn junction operating above its breakdown potential. The shot of the most relaxing sounds imagin- noise resulting from the avalanche break- ONEable is the roar of the surf. From Presi- down mechanism is amplified by Q8. dents on clown. anyone who is close enough. Control voltages for the VCF and VCA and has the time, beads for the seashore origlli a to in the random voltage generator when he wants to unwind. lint what is which consists of three astable multi -vi- really nice is to have the sound of the brators (Q/ -Q6) runnin at different rates surf always available at the flick of a and with different duty -factors. The three switch-and now you can. With a "Surf outputs are summed and appear across Synthesizer," you can turn your home into R18. While the voltage across R18 is to a an apartment at Malibu Beach. certain extent random, it is weighted by the The Surf Synthesizer is actually a special- different periods and duty factors of the purpose electronic music synthesis system astables and the different values of the which operates through vour hi-fi amplifier. summing resistor to approximate the "roll" White noise is generated by an inexpensive of the ocean. silicon transistor and voiced by a voltage - If there is a secret to the Surf Synthe- controlled. 1rn-pass filter and attenuator sizer, it is in the \-CF (DI). \Vhen the finder the control of a random voltage VCA is disabled and only the VCF is operat- gel iera tor. ing, the sound is close to that of the surf

FEBRUARY 1972 45 CIS

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R13 RI4 3SsS333 R15 22K 33K 10K

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Fig. 1. The three astable multivibrators develop a composite volt- tage that controls both the voltage-controlled filter (VCF) and the voltage -controlled attenuator (VCA) to form the sound of the surf.

PARTS LIST

B1,B2-9-volt battery R15,R27-10,000-ohm, 1/2 -watt resistor` C1 -C6-30-µ/', 10 -volt electrolytic capacitor R16-39,000-ohrn, 2 -watt resistor C7 -100-µF, 16 -volt electrolyic capacitor R18 -4700 -ohm, 1/2 -watt resistor C8-10-0', 10-volt electrolytic capacitor R19.R20-1-megohin, 1iá -watt resistor C9 -0.1-µF disc capacitor R22 -100 -ohm, 1A -watt resistor C10 -0.005-µF disc capacitor R -24 -1000 -ohm, 1/2 -watt resistor C11 -0.05-µF disc capacitor R32 -470 -ohm, /-watt resistor C12,C14-0.22-µF Mylar capacitor R34,R.35-50,000-ohm trimmer potentiometer C13-9.21cl". 16 -volt electrolytic capacitor SI-Spst switch (:15-1000-µF, 10 -volt electrolytic capacitor Misc.-Case, battery connectors, batter) D1,D2-1 N94 diode (or similar) clamps, output jack, wire, solder, hardware, Q1 -Q6 2N5129 transistor etc. Q7,Q8-2N2712 transistor Note-The following are available from, R1,R4,R5,R8,R9,R12-6800-ohm, 1/2 -watt re- PAIR Electronics, P.O. Box 14359, Okla- sistor homa City. OK 73116: etched circuit board R2,R10.R21-100,000-ohm, 1/> -watt resistor #3711pc at $3.00 postpaid; kit of parts with R.3-3.30,000 -ohm, 1/2 -watt resistor" circuit board and selected transistor for Q7, R6-220,000-ohnr, 1/2 -watt resistor but less batteries and case #3711K at R7,RI7,R23,R29-47,000-ohm, 1/2 -watt resis- $10.95 plus postage for 1 lb; case #3711C tor at $2.50 with kit order. R11,R25,R26,R30,R31,R33-68,000-ohm, 1/2 - watt resistor if the surf sound is not natural enough, try R1.3 -22,000 -ohm, 1/2 -watt resistor changing R3 to 270.000 ohms, R14 to R14,R28 33,000 -ohm, 1/2 -watt resistor* 22,000 and R15 to 15,000.

46 POPULAR ELECTRONICS Including Electronics World RANDOM the anode of D2 increases, its effective re. VOLTAGE GENERATOR sistance less, 01-06 becomes allowing more signal to pass. Capacitor C12 blocks de from the VCF and does not noticeably contribute to the overall frequency NOISE response. GENERATOR 07 Construction. Since there are no very high Fig. 2. Block diagram shows how ran- frequencies involved and parts place- dom signal is filtered and level con- ment is not critical, any method of controlled by integrated random voltages struction may be used. An etched circuit from three sets of multivibrators. board will make the job easier, however. If you decide to use a board, the foil even though there is no amplitude change. pattern is given in Fig. 3. Component lay- If, .on the other hand, the VCA is working out is also shown in Fig. 3. Leave transis- alone, the result only sounds like inter - tors Q7 and Q8 till the last; their selection station radio static fading in and out. and installation are explained later. Be sure The VCF uses the nonlinear V-1 char- to get polarized components properly in- acteristic of a conventional silicon diode as stalled and use a heat ink on the semi- a voltage -controlled resistor. By proper ad- conductor leads when soldering. In fact, it is justment of R.34, diode Dl is ordinarily good practice to save the installation of forward biased, resulting in a loss of high all semiconductors for last so that the heat frequencies through C11, D1, and C13. As from soldering adjacent components cloes the control voltage of the VCF increases, not damage them. it reverse biases D1 and allows less high_ When all of the components except Q7 frequency loss to ground. The high fre- and Q8 have been installed, connect the quencies not shunted to ground naturally positive lead of one of the battery con- become part of the output signal. nectors to the circuit board point marked The operation of the VCA is similar to "+" and the negative lead of the other that of the VCF. Diode D2 is in series to point "G". Solder the remaining lead with the signal and is slightly reverse biased from each connector to either side of by R35. As the control voltage appl.ed to switch SI. Also connect the output jack to points "A" and "G" with wires that will be long enough to reach from the location of the jack to the circuit board when it is installed in the case. To select Q7 and Q8, remember that not every 2N2712 breaks down when its base - emitter junction is reverse biased with 18 volts. However a piece -by -piece survey of over 50(10 transistors indicated that approx-

Fig. 3. Actual size foil pattern and component layout. Take care when installing semiconductors, diodes, etc. See text before installing Q7 and Q8.

G C16 C 05 0 C 03 02'C+ ' 5 3 RIB OC C O +6. 14 1` . tR15tt tRt14t iTR13 r ` ;7T3#2}RUd R91t111111R1`' C+27 R16 R25C2 t RI241 t C+4+71 Ia8.1R19 1 .bOt R28 R35 ¡6 it34 R1 : 9 1.C13 .

FEBRUARY 1972 47 wood screws through the aluminum. Holes were cut in the back of the case to provide clearance for the output jack and the ,..5" "(I ryr,r....r ' power switch. The battery clips were glued to the top of the channel. The circuit board was fastened to the aluminum bottom plate with 4-40 hard- 82 ware and ii" standoffs. The bottom plate was fastened to the wooden ends with #4 screws. JI -SI

o t Setup and Operation. The only adjust- n ments to be made on the Surf Synthesizer é are the settings of R34 and R35. While t' gym. d ,mob o these settings are large y a matter of per- _b Ys +y,Wpt sonal preference, a couple of tips will get you started. . t^UI .. r Connect the Synthesizer to an ampli- A «; rte t y`0 fier and turn both on. With R3.5 set fully clockwise, adjust R34 for the widest and Interior view of author's prototype most natural sounding tone changes. When shows method of mounting boards and you are satisfied with the adjustment of the location of both of the batteries. tone control, you can set R.3.5 for volume changes. You will probably find that the most natural sound results when the Synthe- imately 80% of them were suitable for use sizer is completely muted for short periods as a noise source. Since two of these tran- of time. There is little electrical interaction sistors are used in the synthesizer, there's between R35 and R34, but it will probably a good chance that one can be used for take some twiddling before you are com- Q7. Arbitrarily select Q7 and Q8 and pletely satisfied with their adjustments. lightly solder them in place. Note that the Bear in mind that the quality of the collector of Q7 is not connected to any amplifier used with the Synthesizer Will point in the circuit. Rotate R.34 and R35 greatly affect the final sound. Use an ampli- fully clockwise as viewed from the nearest fier with the best bass response available edge of the board. Run a jumper from the so that the "roar" of the surf can be heard output jack to the low-level input of a hi- as well as the crescendo-like crash as the fi or instrument amplifier and adjust the waves break. It will probably be necessary amplifier's gain about midway. Install two to advance the bass boost of the amplifier 9-volt batteries in the Synthesizer and turn to achieve a really natural sound. on Sl. You should hear a rushing sound from the amplifier. If you don't, unsolder Q7 and Q8 (being careful to avoid over- heating) and interchange them. When you are sure that Q7 has been properly selected, solder it and Q8 permanently in place. This is a good time to check the voltages at the collectors of Q2, Q4, and Q6 to make sure that all three astables are operating. Use any \'TV\l set to a 20 -to-25 -volt scale. The voltage on the collector should go from about g to 17 volts and have a period of several seconds. The Surf Synthesizer ma'. be housed in any convenient case. In the prototype, the case was made of sheet aluminum folded into a U measuring about 5" x 23_" x 3;4". The ends of the U were sealed with walnut blocks hay in. a rabbet cut around each edge. The ends are held in place by #4 World 48 POPULAR ELECTRONICS Including Electronics Computer Core Memories Still Handmade

T IS an ironic fact that one of the most and costly parts of modern com- critical -P w- puters is produced by handwork more ex- - acting than the finest embroidery. This is ~:`i^ Y1 the core memory, the portion of the com- g`-` y puter that stores information for high-speed I d1F . electronic calculation-and transfers. it at r- in billionths of seconds. speeds measured w , of this central memory, , r The performance -. r, more than any other part, determines how efficiently a computer can do its job. to fact, a core memory may account for more than half the cost of a large high-speed computer. The cores are tiny rings of an iron oxide .- material, some less than a fiftieth of an inch in diameter. Each core may he magnetized \ rt in a clockwise or counterclockwise direction to store a unit (hit or binary digit) of Common #7 needle and 00 thread computer information. dwarf cores and wires in typical section Women's deft hands string these tiny of Ampex computer memory. Each core heads together with hair -like wires. tlp to stores unit of computer data. Three three wires may be run through the almost wires go through center of each core. invisible center of the core. The wires carry writes. or erases electric current that reads, Aided by powerful microscopes, skilled As the information in each indi\idual core. women weave hair -like wires and tiny many as ten million cores may be contained ferrite cores into a computer memory. in a single memory. For years, computer designers have sought ways to automate the production of high-speed memories and eliminate this handwork. Various methods F Ii' have been tried at great expense, but none -4 has vet emerged that can equal the com- . bination of speed, economy and reliability 9, that hand -wired cores achieve. Semiconductor memories with higher operating speeds are beginning to be used in some of the newer computers. Such memories have shown up to three times the speed of core memories, though they have vet to equal their economy. But the core will continue its vital role for many years to come. Further increases in core speed, economy and compactness are certain. Be- sides there are more than 50,000 computers in use in the world today that rely on core memories. Since these computers have been designed with cores, it would require radical and expensive changes in the computer itself to replace existing core memories with semic mductors.

FEBRUARY 1972 49 HAT STARTED OUT only a short time ing; while others have large necks, which ago as a sort of token acknowledgement means greater deflection power is needed. of integrated circuits in color TV receivers Although the Americans are indecisive, the is now blossoming into full-scale usage; and Europeans will probably select the thin -neck they are being accompanied by other solid- version using a dual toroidal yoke for both state devices such as plug-in modules, vertical and horizontal deflection. Varactor tuners, and high -voltage doublers Here is what three typical manufacturers and triplers. Add to this, new developments have in store for us. in CRT's and yokes, and it looks as if color TV reception is about to take some giant Motorola. Semiconductor research, devel- strides. Most TV manufacturers have asso- opment, and manufacture for Motorola is ciated themselves with IC producers (either carried out at Phoenix, Arizona, while the separate companies or branches of their own receiver plant is at Franklin Park, Illinois. organization) in order to make maximum Ideas advanced by the R&D engineers at

NEW IC'S AND MANY NEW CIR(L ITS AND NOVEL CIRCUITS WILL SOON BE FOR COLOR TV FOUND IN COLOR -TV RECEIVERS use of semiconductor technology in con- Phoenix are not always immediately evident sumer applications. in the sets from Franklin Park. RCA is now using five IC's in their cur- For instance, the 10 -IC color -TV receiver rent line, and Motorola will soon equal this whose block diagram is shown in Fig. 1 may -in addition to using a new horizontal well represent the solid-state future (but not line frequency switched power supply. the present) for Motorola. Except for the Zenith is also introducing plug-in transistors unshaded blocks, representing the uhf and and IC's, while General Electric has started vhf tuners, horizontal driver and output its first solid-state monochrome production amplifier -damper, the low-level video am- line with some interesting circuit innova- plifier, and the chroma outputs, every other tions. CE is also looking into the possibility circuit is an IC, currently in the works. of an advanced color receiver for next fall. There appears to be no logical reason why Not all the changes are in semiconductor the unshaded blocks could not be IC's circuits. For example, Sickles (G.I.), a TV shortly. Motorola certainly makes some ex- component manufacturer, is using a special cellent high -frequency transistors and Va- alloy in its deflection yoke cores to change ractor diodes, so the front end is a real pos- permeability with temperature and oppose sibility. More than likely, the other blocks convergence drift due to heating. The drift are also being designed. is reduced from about 9% to close to 1%, But making an integrated circuit out of a resulting in a more color -stable picture (lur- discrete -component circuit is not all that ing long hours of use. easy. A lot of sophisticated thinking went As for the color tube itself, the 110° tube into the video detector portion of the IC presently in wide use suffers from one big that is the i -f amplifier detector shown in problem: lack of industry standardization. Fig. 2. Conventional video detectors use a Some are made with small diameter necks, semiconductor diode, which, being non- which can possibly mean more internal arc- linear, often produces "birdies" (undesirable

50 POPULAR ELECTRONICS Including Electronics World S11/11 and difference signals) that disturb the The overall detector is switched at twice picture. The partial circuit shown in Fig. 2 the carrier frequency (with Q3 conducting is a double -balanced, full -wave, synchronous on the positive half cycles and Q4 on the circuit with linear detection and frequency negative half cycles), producing waveform response to 6 MHz. Transistor Q7 is a con- (I)) in Fig. 2. This is the waveform across - stant current source, QI and Q2 form a dif- R1. Note that the original carrier no longer ferential amplifier, and Q.3 through Q6 are exists and the detected modulation is con- carrier operated switches. The three inputs structed of pulses of double the original car- are derived from the video i -f amplifier por- rier frequency. The stages that follow the tion of the same IC. basic detector have a limited frequency re- only the lower - . When positive half cycles of the ampli- sponse and amplify tude -modulated carrier appear at the base frequency components (modulation), thus of Ql, the transistor conducts. The in -phase making the detector self -filtering for any clipped carrier that simultaneously appears high -frequency products. So the detector need not he shielded to prevent spurious radiations of the i -f and harmonics of the i -f from getting into other circuits and causing \ anions types of unwanted moire patterns.

Fairchild -Warwick. IC manufacturer Fair- child Semiconductor and receiver maker Warwick Electronics have combined their skills to demonstrate a complete monolithic color processor on a 20 -pin package. if the idea of a 20 -pin IC frightens you, consider the fact that this single package requires only 42 external components as opposed to the 62 to 77 required by the active 2- and 3 -package systems presently under consideration. This new chroma subsystem (Fairchild Above are RCA hybrid networks built /1A782) includes a 3.58-Mliz oscillator/am- on ceramic substrates for color N. plifier, an oscillator phase control, an automatic phase control detector, and automatic at the base of Q.3, will cause that transistor color control circuit, i -f gain control, to conduct and allow more current to flow chroma i -f amplifier, chroma demodulator, through RI. No current flows through Q4 and color killer. The other necessary ele- since it is switched off by the out -of -phase ments are a :3.58 -MHz crystal, chroma clipped carrier. When the negative half cy- bandpass transformer, oscillator RLC phase - cles of the modidated carrier appear at the reference tuned circuit, phase and color base of QI, it turns off. but Q2 conducts level potentiometers, and assorted resistors through the differential action. The reverse - and capacitors. phase carrier pulse turns Q4 on causing the current through R1 to increase. No current General Electric. The General Electric flows through Q.3 since the in -phase carrier engineers at Portsmouth, Virginia, are pulse is negative at this time. The current proud of their new U-1, a 21 -transistor, 16 - flow through R1 increases for either posi- diode, i -IC monochrome receiver for 1972. tive or negative half cycles of the carrier, Two discrete -component circuits are espe- thus causing a voltage change at the col- cially interesting. lector terminals of switched transistors Q3 The three -stage video i -f strip shown in and Q4. Fig. 3 uses only one transformer (T101) The reverse action takes place in R2 due coupling the i -f to the detector. This circuit to Q.5 and Q6. Curve (A) in Fig. 2 shows is the result of 2 years of work on RC cou- an amplitude modulated carrier as it would pling techniques, providing a minimum of appear at the base of Q1, while Q2 would tuned circuits to process the relatively low- see the same signal inverted. The two level video information. clipped carrier pulses are shown in curves The band shaping is performed by series (B) and (C). inductor L104 and the detector transformer,

FEBRUARY 1972 51 r - r r I -I I SO,VNO I AUDIO . IF, AND »T AMPLIFIER OETECTOR I 1

J I I J FE

r THIRD LOW VIDEO I I V DEO ' I I VIDEO LEVEL If IF DETECT15R VIDEO

I . AA}p..IF 1 I AMPLIFIER STAGES) __I L

r--- r , I I s ... ' xn I VIDEO P i--- C FIROM! CHROMA OUTPUTS ' - -J fi 1MPLIPIFIERz I

: SYNC fhiavor01- 1 r 1 SEPARATOR CHROMA bpMODULATOR 1

I _ 1 SUBCARRIER , I I L J SYSTEM AUTOMAT! r 1 Pt'ASE CONTROL DASHED BOXES .VERTiCJt- BERTICA4- INDICATE THE i OSCILLATOR "OUTPUT L _J AVAILABLE i Y FUNCTIONS IN L J YOKE MONOLITHIC INTEGRATED . CIRCUITS LI HORIZONTAL I HÓRa10)IiTAL 1 AFC - 'RCP"' >r H L YOKE t Fig. 1. Shaded blocks in this diagram of Motorola's experimental color TV receiver are available now as integrated circuits. When design of the remaining circuits is complete in integrated form, the set will be all -IC.

01 180° REVERSE PHASE BASE CLIPPED CARRIER IN PHASE,.á I CLIPPED CARRIER Q3 BASE

Q4 MODULATED CARRIER BASE

Fig. 2. Motorola's unique approach to video detection is a double -balanced, full -wave, synchronous detector, eliminating usual diode detector birdies. b V

52 POPULAR ELECTRONICS Including Electronics World FROM VHF TUNER +22V +22V 8117 270(1

CI 16 1 11°---j- CIII .OIpF .001yT

R102 _ RII0 470(1 150(1 R101 On ITO VIDEO C1061 )DETECTOR R106 RIII R116 .OIyF II CIRCUIT 390(1 270(1 8.2K C109 C113 .001NF .00IyF CI01 C102 1ST IF 2ND IF 39pF 15pF 11104 Q101 3F1 QI02

C104 18pF ,1 R114 RI09 -`\ 2.2K 680(1 101 IL102 47.2 39.75 41.25 4IO35 MHz MHz MHz R105 R118 18011 CIIS 39011 820pF L ------J R108 IF --- AGC - loon INPUT

C08 CI 12 150pF R 112 I 20n RIII 1501 TO RF A6C

Fig. 3. This three -stage video i -f strip by General Electric uses resistor/capacitor coupling and special emitter bypassing to eliminate more standard i -f transformers. Technique provides a minimum of tuned circuits for low-level video information. It will be in GE's U-1 monochrome units. with the emitter bypass capacitors selected tor is used as the buffer between the "oscil- for maximum gain within the bandpass. lator" and output stage, while the other Using a 45-AIIIz i -f center frequency, this transistor acts as a variable -gain feedback circuit places the 45.75-MIIz video carrier amplifier. The circuit arrangement is such at the 50% point on the response curve, that the active portion (4 transistor, 2 di- and the 42.17-MHz chroma carrier at the odes, resistors, etc.) lends itself readily to an correct 50% point on the other side of IC format. the skirt. The i -f age is fed (via R109) to the base Other Things in View. Obviously, these of the second i -f amplifier Q102, with posi- three companies are not alone in their TV tive forward feed age for the r -f stage gen- advances. Other semiconductor and re- erated at its emitter. This approach was ceiver manufacturers are working to devel- used to prevent excessive current drain on ope new IC's and fascinating circuits so that the age kever stage. The overall circuit they can get their share of the multi -million develops maximum gain from three i -f dollar color -TV market. stages and permits 275 lines of horizontal Keep your eye also on what is going on resolution and full 3.5 \IHz bandpass, abroad. \Vith the beginnings of an IC indus- which is substantial enough for color and try in Japan, and with their usual excellent excellent for monochrome reproduction. approach to miniaturization, it is possible to The other GE circuit is a four -transistor expect some really marvelous things from vertical oscillator and output system. In there in the next year or two. One of their this circuit, the so-called oscillator stage and major contributions, the Trinitron color tube the output stage are cross -coupled to create by Sony (with a non -shadow mask and sim- the overall vertical sweep system through ple convergence adjustments) is probably use of positive feedback. A single transis- just a preview of things to come.

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FEBRUARY 1972 57 ECEIVERS, like almost every other oscillator built into the receiver is tuned kind of electronic equipment, have to 5.455 MHz and is coupled to the mixer. grown increasingly complex-primarily When a nonlinear device has two such because people expect so much more of signals fed into it, there are four signals them in terms of performance and ver- at the output: 5.000, 5.455, 10.455 and satility. Almost all of the bands, com- 0.455 MHz. By following the mixer with mercial and amateur, are getting so con- a selective tuned circuit and amplification gested that selectivity poses a real (the i -f amplifier) at the difference fre- problem in the design of a good high - quency (455 kHz) considerable improve- frequency receiver. Single sideband, with ment in selectivity can be achieved as all of its advantages, has brought with opposed to the mere amplification of the it the need for stability far greater than 5.000 -MHz signal alone. Why? Because that required for conventional AM. And, the higher the frequency of a tuned to top it all off, everyone wants receivers circuit, the less selective it becomes. For that are smaller and more compact. this same reason, the sum frequency The appearance of the transistor pro- (10.455 MHz) was passed over. vided the answers to some of these problems. Space and weight could be trimmed Double Conversion. In considering the significantly, while heat, long one of the layout in Fig. 1, a logical question arises: big enemies of electronic equipment, Why not move the local oscillator fre- could be almost eliminated. However, quency nearer to that of the received transistors had problems of their own- signal? This would lower the frequency leaving a lot to be desired as far as of the i -f amplifier and provide even more stability, overload, and circuit design improvement in selectivity. This is true; were concerned. but, as the i -f frequency is lowered, Then along came integrated circuits and problems of another nature arise. field effect transistors. The IC brought The mixer is not selective enough to more space reduction and, in some cases, attenuate aII signals other than 5.000 simplification of circuits. The FET has MHz-especially those close to 5.000 solved many of the overload problems MHz. If, for example, a strong signal at connected with bipolar transistors. The 5.910 MHz appears at the input, it too FET high input impedance has almost will mix with the local oscillator fre- eliminated loading of tuned circuits, re- quency and will also produce a difference sulting in higher Q's and improved se- frequency of 455 kHz. This will be am- lectivity; and the low noise of FET's has plified in the i -f amplifier, producing what improved sensitivity. So it is now pos- is called an image of the other 455 kHz. sible to design and build a solid-state Images can appear anywhere in the tun- receiver that is equal to, or even better ing range of the receiver. than, its vacuum tube counterpart. Most electronic experimenters choose to buy factory built receivers because they feel the task of constructing one is beyond their capabilities. This is not necessarily the case. They build many other electronics projects that are just as complicated. Perhaps a better understanding of just how a solid-state receiver is designed and how it works would cause many to try constructing one for Finiilaineiital s themselves.

The Basic Superheterodyne. A block dia- of gram of the basic superhet system is shown in Fig. 1-applicable to simple Solid -State BCB units, FM receivers, CB rigs, radio control, etc. Assume that the input circuit of the Receivers mixer is tuned to 5.000 MHz. A local

58 POPULAR ELECTRONICS Including Electronics World Thus, it can be seen that moving the However, double conversion receivers local oscillator frequency closer to the are not without their drawbacks. Every received signal brings the images closer time an oscillator is added, chances of and makes it more difficult for the tuned spurious responses increase considerably, circuits to attenuate them. Adding more so quite a few single conversion receivers tuned circuits between the antenna and are still to be found. But, instead of a the input to the mixer will help, and this low i -f frequency, they use a frequency is one reason for adding an r -f amplifier. as high as 9.000 MHz to reduce the image However, as receivers are called upon to problem. The development of excellent get signals of higher and higher fre- crystal filters for this frequency range has quencies, the number of tuned circuits helped to solve the problem of selectivity needed to solve the image problem be- for these single conversion units. comes prohibitive. One solution is to use double conver- R -F Amplifier. An r -f amplifier is in- sion as shown in Fig. 2. Now, with the cluded in high -frequency receivers for same 5.000 -MHz input, the first local two main reasons: to increase the level oscillator is tuned to 11.000 MHz; and of the antenna signal to a point where it the output of the first mixer is 6.000 MHz, will override the noise generated in the the difference frequency. The image fre- mixer, and to offer discrimination to quency is now 17.000 MHz, which is far spurious signals. Too much amplification enough away from 5.000 MHz to be can create problems with cross -modula- attenuated. tion and blocking. which can occur when To get a lower i -f frequency for better one stage of the receiver (the r -f or mixer) selectivity, the second mixer is fed by is overloaded. a local oscillator at 6.100 MHz, and the The circuit of an r -f amplifier using a difference frequency of 100 kHz is am- dual -gate FET is shown in Fig. 3. The plified and detected. FET works well as an r -f amplifier be- In addition to solving the image prob- cause of its excellent "square -law" be- lem, double conversion can be a real haviour, which means that a frequency asset in improving stability. An oscillator applied to its input appears at the out- is always a source of frequency drift in put along with the frequency's second a receiver, and the higher the frequency, harmonic-and no other harmonic. If the the greater the problem. In some double circuit is tuned (as in an r -f amplifier), conversion receivers, the first local os- the second harmonic is of no importance cillator is crystal -controlled for stability, since it will be eliminated. The square - and the second, working at a much lower law behaviour of a FET is much better frequency, takes care of the tuning. Over- than that of a bipolar because the latter all stability is thus considerably improved. has characteristics similar to a diode, resulting in more harmonics. In the circuit shown in Fig. 3, the signal is applied to one gate of the dual - gate MOSFET, while automatic gain control is applied to gate 2. This use of feedback to control the gain on the second gate is one of the big advantages of the dual -gate FET. As mentioned previously, the FET also has a high input impedance New semiconductors, so that it does not load the tuned cir- new IC's, and new circuits cuit and it makes possible a very high Q to prevent spurious signals. make much better Mixer. As its name implies, the mixer receivers possible stage takes two signals, mixes them, and provides outputs which are the sum and difference of the two. By selecting the proper output, a high frequency can be BY JIM WHITE, W5LET converted to a much lower one. Any nonlinear device can be used as

FEBRUARY 1972 59 a mixer: diodes, bipolar transistors, or quency can be shifted, either by con- FET's. Usually the diode is not used at ventional tuning, or by bandswitching in- lower frequencies because there is a ductance and capacitance. Such an oscil- signal loss in conversion, and the char- lator normally would be too unstable, but acteristics of a bipolar limit its useful- in this case it is phase -locked to harness when handling strong signals. monics of a very stable crystal oscillator. Here again, the dual -gate MOSFET is Though somewhat more complex, this ar- preferred-even over the junction FET or rangement offers excellent stability, a re- single insulated gate FET. The second duction in the number of crystals needed gate is used for the local oscillator input (usually only one or two), a much wider (see Fig. 4). With the r -f input on gate range of frequencies, and simplified 1, the signal and the oscillator are well switching. isolated. This eliminates a problem called A block diagram of a phase -locked "pulling," which means that the tuning of oscillator is shown in Fig. 6. A precision the mixer causes a shift in the frequency 500 -kHz crystal oscillator drives a har- of the oscillator. monic generator, which provides good, A mixer using a junction type FET is strong harmonics to frequencies well shown in Fig. 5. Like the circuit in Fig. above 30 MHz. These harmonics, appear- 4 it provides signal gain while converting ing at every 500 kHz, are fed to a phase the input to the i -f frequency (conversion detector which also receives the output gain), but the isolation of the oscillator of the tunable oscillator. As long as the frequency is not as good as provided by tunable oscillator is at an exact multiple the circuit in Fig. 4. of 500 kHz, the output of the phase detector is zero. However, if the oscillator Local Oscillator. In the simple super- drifts, the output voltage of the detector, heterodyne, the tuning range of the local which is coupled to a variable capaci- oscillator must maintain the difference be- tance diode connected across the oscil- tween its own frequency and that of the lator tuning coil, brings the oscillator fre- input so that the i -f frequency is always quency back to the correct value. With the prescribed amount-in the case of proper design, a phase -locked oscillator the example used here, either 455 kHz has extremely good stability-even bet- above or below the signal. This fre- ter than some crystal oscillators operat- quency difference must be maintained ing at higher frequencies. throughout the frequency range of the For those interested in a simpler ap- receiver if the i -f amplifier is to pass and proach, Fig. 7 is a crystal -controlled oscil- amplify (called "tracking") the mixer out- lator using a junction FET. The circuit in put. the drain is tuned to the crystal fre- Many modern double conversion re- quency. For multi -band operation it is ceivers use a crystal -controlled first local necessary to switch crystals and tuned oscillator to improve stability at high fre- circuits. quencies. The second local oscillator, As mentioned previously, many receiv- operating at a much lower frequency is ers have a tunable second local oscillator tunable. In addition to providing stabil- that determines the frequency stability of ity, this method assures the same tuning the receiver. In the circuit shown in Fig. range on all bands and makes calibration 8, a buffer stage is included to provide easier because the oscillator's tuning more isolation and minimize "pulling" of range is the same on all bands. Several the oscillator. The oscillator uses a single - types of communications receivers used gate MOSFET, while the buffer is a con- by amateurs utilize this principle, and ventional bipolar transistor. often as many as a dozen crystals are used in the first local oscillator. I -F Amplifier. No mention has been made If more expanded coverage is desired, so far about the use of integrated cir- the designer must include more crystals cuits. Why? Simply because there does and a more complex switching arrange- not seem to be any IC that equals the ment. Some of the more expensive and performance (in the circuits discussed so complicated receivers, designed to re- far) of the devices suggested. With the ceive signals between 500 kHz and 30 i -f amplifier however, it's a different MHz, have a first oscillator whose fre- story. There are several IC's available

60 POPULAR ELECTRONICS Including Electronics World (.455MHz)

R.F. INPUT MIXER I. F. DET. AUDIO - - OUTPUT (5MHz)

Fig. 1. This is a simple single -conversion LOCAL superheterodyne as used in most receivers. OSC. The i -f is 455 kHz, which is somewhat stan- (5.455MHz) dard, but other frequencies could be used.

(6MHz) (100kHz) _ R.F. FIRST SECOND INPUT - DET. AUDIO - bUTPUT (5MHz) MIXER MIXER

Fig. 2. Double conversion superhet uses a crystal -controlled local LOCAL LOCAL first OSC. OSC. oscillator and a variable second for actual tuning. Image rejection is better (11MHz)- (6.IMHz) than in single -conversion type (above).

Fig. 3. Here, the dual -gate To MOSFET r -f stage has its gain MIXER controlled by a negative voltage which shown is applied to gate 2.

Fig. 4. This mixer also uses a R.F. AMP dual -gate MOSFET, with the local I. F. oscillator signal applied to gate 2 of the transistor; r -f on gate 1.

TOR.F...1i CORRECTION VOLTAGE AMP.

TO FIRST. TUNABLE PHASE OSC. DE T. T MIXER 1.0 (500kHz)

CRYSTAL HARMONIC OSC. GEN.

Fig. 5. This circuit shows how a Fig. 6. This tunable oscillator is junction FET can be used as mixer. locked to harmonic of crystal fre- There is less isolation than when quency and kept on frequency by the dual -gate MOSFET is employed. the action of the phase -locked loop.

FEBRUARY 1972 61 Fig. 7. Typical crystal -controlled oscillator using a junction FET. The tuned circuit in the drain is set to the crystal frequency. For a different frequency, both crystal and the tuned circuit components must be changed.

+ R EG.

TO Fig. 8. This tunable circuit is MIXER used as second local oscillator with a buffer stage to provide isolation from the mixer circuit.

CERAMIC +6-15V FILTER Fig. 9. This IC i -f stage provides INPUT -I 0.8 volt output from an input as low as 50 microvolts. The circuit AUDIO also has agc range of 60 decibels. .01 pF

.0I p F

+ 6V 100K 1.6K .OIyF

OIPF

47K 8.2 K

Fig. 10. The integrated circuit used MFC- 4010 OUTPUT

in this i -f strip costs only $1.50 CERAMIC CERAMIC and provides 70 dB gain at 455 kHz. FILTER FILTER

AUDIO OUTPUT

1 TO T--"T BFO

Fig. 11. This simple product detector for CW and SSB applications uses a back-to-back dual diode arrangement.

AUDIO H AUDIO INPUT IuF Fig. 12. There are many available integrated circuit devices that can be used in the audio amplifier stage. Some will provide up to 5 watts output.

Electronics World 62 POPULAR ELECTRONICS Including that certainly do an excellent job here. the pitch can be varied tc suit the What do we expect the i -f amplifier to operator. do? Amplify, of course; but it is here that In receiving SSB signals, we must re- we seek to achieve much of the receiv- member that the carrier was suppressed er's selectivity. It is possible to provide at the transmitter so that the receiver amplification very simply with an IC; must supply the carrier. This is done by but selectivity must be added, usually in the beat oscillator operating with the the form of a crystal or mechanical filter. sideband to produce audio: Just as with Recently, also, ceramic filters have been CW, the beat oscillator must be posi- used and they offer some advantages, es- tioned properly as far as frequency is pecially in size and cost. A ceramic filter concerned for best results. approximately 1/4" square and 3/4" long Why a product detector? Because the can be bought for less than $15 and it can regular diode detector most often used be combined with an IC to make a very with AM will introduce severe distortion good i -f stage. unless a proper balance is maintained Generally speaking, most crystal filters between the signal and the beat oscilla- used today are of the higher frequency tor. This is difficult to do. In most receiv- types (up to about 9 MHz) and the me- ers lacking a product detector, it is nec- chanical filters are for lower frequencies essary to reduce the signal input with the (to about 500 kHz). r -f gain control. With a product detector, Space does not permit a description of which is really a mixer -type demodula- all of the IC's that are available for an i -f tor, the requirements as to the ratio be- amplifier. One typical example, however, tween the received signal and the beat is shown schematically in Fig. 9. De- oscillator is much less critical so the signed for AM use only, it provides 0.8 audio is much "cleaner." volts, peak -to -peak with inputs as low as One very simple product detector cir- 50 microvolts at pin 2. It has an ex- cuit. with back-to-back diodes, is shown tremely good agc network as well as an in Fig. 11. The beat oscillator must be AM detector. The agc range (referred to stable and also must have sufficient out- pin 2) from 50 microvolts to 50 millivolts put. Because of the need for exception- is 60 dB. The IC is in a TO -5, 8 -pin case ally good stability in the BFO, many and with four capacitors and some means manufacturers use crystal -controlled os- of achieving selectivity, it makes a good cillators. Usually two crystals are pro- AM i -f strip. The IC is an LM -372. vided so that the frequency will be correct A schematic of an i -f strip built around for either upper or lower sideband when a new, low-cost IC recently announced receiving SSB. by Motorola is shown in Fig. 10. It is ex- trer''l r small. but provides a gain of up Audio Amplifier. The use of an IC in the to 70 dB at 455 kHz. The IC is about $1.50. audio portion of a solid-state receiver is the only logical approach. There are Product Detector and BFO. Most modern many available to do the job. One pos- receivers use one form or another of a sibility is the circuit shown in Fig. 12. It product detector for SSB and CW recep- uses a minimum of parts and operates tion. To understand why a product detec- with a 12 -volt input. An RCA unit uses a tor is desirable, we must review some maximum of 9 volts. The General Elec- basic facts about these two modes of tric PA -234 provides 1 watt; the PA -237, transmission. First, with both SSB and 2 watts. CW, something must be added at the receiving end to produce audible signals. Other Considerations. There are many With CW we have a carrier, but no audio other factors involved in the design and modulation. So an oscillator is built into construction of a solid-state receiver. Not the receiver with a frequency very near all of them can be covered here, but most the i -f. When the two are mixed (beating of them have to do with mechanical de- against each other) a signal in the audio tails. For instance, it is almost imperative range is produced. It is the same princi- to use printed circuit techniques, and the ple as in the mixer stage except that the construction should be good and solid. output is an audio beat. Usually the beat The power supply must be of the well - oscillator is variable in frequency so that regulated, solid-state type. O

FEBRUARY 1972 63 Communications

. Scene. ..S .1111111111:. ' I By Richard Humphrey

T IIE Citizens Band-and unless mention Radio Relay League is hard to say. At is to the contrary, we mean the 27 - first glance, you'd say that the basic job MHz class D band-has gone through its of such an organization should be the adolescence and should now be ready to same as the ARRL's: to represent its undertake the responsibilities of members in all the necessary ways. This communications adulthood. makes sense. But then the similarity ends. This demands the creation of a national It's just a different scene, that's all. It can organization to put together and propose be argued that more "communicating" rule changes to the Federal Communications is done on 27 MHz than on all the ham Commission, to promote the interchange bands combined. of news and information of interest to the Yes, a national CB organization CB community, and to figure out some should represent its members. But for fm -ti 1.f self-policing, possibly like that their reasons and not what somebody else wr i by the amateurs. thinks is good for them. Whether or not such a group should be patterned after the amateur's American Who Speaks for the CB'er? Some of the efforts to weld Citizens Band licensees into a national group have been mildly successful, others have had a brief moment of glory then died, some just never seemed to get off the ground. This is not to underrate their efforts-or the work of groups like The REACT, which, after all, is primarily interested in help in emergencies and doesn't enter into the discussion; or the Case publications devoted either entirely or in part to CB activities; or even industry - oriented groups with obvious aims. for a The point is, no one speaks for the Citizens Band population as a whole. And such a speaker is needed, For instance, magazines devoted to National amateur radio and many groups with the same interests make valuable contributions; but when the chips are down, it's the CB ARRL that's snapping at the FCC's kneecaps for rule changes-or defending some ham wrongly accused of TVI. Organization The need for a national organization to carry the CB torch was pointed up by the application last year by the Electronic Industries Association to the FCC to establish 80 CB channels in the

64 POPULAR ELECTRONICS Including Electronics World 220 -222 -MHz band. If the idea is approved by the FCC, the Electronic Industries Association possibly will have rendered the CB'ers a valuable service. But shouldn't this petition for rule changes have been submitted by a Citizens Band association rather than an - association representing the manufacturers of CB equipment? And there's no reason \vhv the EIA could not have clone most of the leg work for a CB organization in such a circumstance. It's perfectly ethical and is common practice in many communications areas. To carry the argument a bit further: the Electronic Industries Association Ska da0d 5`ete° petition sparked a vigorous protest in the September (1971) issue of QST. (The Sddáe` `daP°` 2:0e6*/ ARRL got into the battle to protect the eyoFM 1r

66 POPJ'.AR ELECTRONICS Including Electronics World To each hirown.

Not everybody needs a concert grand piano, nor does everybody need the best cartridge Shure makes to enjoy his kind of music on his kind of hi-fi system. Eventually, you'll want the renowned V-15 Type II Improved, the peerless cartridge for advanced systems and ample budgets. But, if your exchequer is a little tight, consider the M91E, widely acclaimed as the second best cartridge in the world. With a sharply circum- scribed budget, all is tar from lost. Choose any of the four models in the M44 Series, built for optimum performance in the easy -to -take $18-25 price range. Write for a complete catalog: .-...r.1: ti Shure Brothers Inc., S 222 Hartrey Ave., Evanston, Illinois 60204. H V R E CIRCLE NO. 38 ON READER SERVICE CARD

FEBRUARY 1972 67 The two r -f transformers, T2 and T3, are conventional 262 -kHz types with trim- Tuner mer capacitors to bring their frequency down to the 160 -190 -kHz range. The antenna coil, Ti, is a TV horizontal Ividth coil with 30 turns of #28 enameled wire added as the coupling coil. for the The tuner has three controls: RI5 for audio gain, R18 for r -f gain, and S2, the standby switch. The ac control switch, Sl, is mounted on R15. Neglected Construction. The prototype of the tuner was built on a 7" X 9" X 2" aluminum chassis (the same as the transmitter) and the general layout is shown in Fig. 2. The large holes for tubes, transformers, etc. Band were made with chassis punches, while all the smaller holes were drilled. Mount the components so that interconnecting leads are as short BUILD THIS COMPANION as possible. A number of terminal strips were used below the chassis to TUNER FOR THE support most of the components. The trimmer capacitors for T2 and T.3 were soldered LICENSE -FREE TRANSMITTER directly to the appropriate terminals on the transformers. DESCRIBED LAST MONTH The 30 turns of #28 wire on T1 are wound directly on top of the coil and in the same BY JIM WHITE/W5LET direction as the turns on the coil. When wiring T6, the oscillator coil, be sure to follow the manufacturer's recommended connections or the converter will not oscil- a\IONTH, late. LAST we described a one -watt transmitter for the 160 -190 -kHz band. This month, as promised, we will discuss a Adjustments. \Vith the power turned on, companion long -wave tuner. make sure that all four filaments heat up, The circuit, shown in Fig. 1, uses four and carefully check for the presence of conventional vacuum tubes and requires only an audio amplifier and antenna to make This bottom view of the tuner shows it a top-notch receiver. Headphones can be how point-to-point wiring was used. connected directly to the audio output if The adjustment for T6, the oscilla- desired. Both VI and V2 are r -f amplifiers tor coil, is near top right corner. and are adjusted to the same frequency as the transmit ter you will be receiving. The very low power of the transmitter makes it necessary to have a sensitive tuner, so two r -f stages are used. Also, two r -f stages provide a better rejection of strong BC13 signals that can creep into a low - frequency converter. The use of two fixed tuned stages also eliminates the problem of tracking, with its increase in cost. Following the two r -f stages is V.3, a converter stage, where the input frequency is changed to 455 kHz. This is then amplified by V4. Diode DI is both the a-rn detector and age device. The power supply is a conventional half -wave type.

68 POPULAR ELECTRONICS Including Electronics World if you go for four channel...

snnut " 1

you don't have to go for broke

Buy yourself a miracle for as little as $209.95. That's all The QS500 features three balance controls for front -rear it takes to get your conventional two -channel stereo to do and left -right, separate positions for decoding and synthesiz- anything any total four -channel receiver and control center ing, two -channel and four -channel tape monitors, electrical can do, now or in the future. rotation of speaker output, alternate -pair speaker selection, The Sansui QS500 and QS100 converters are complete and four VU meters. Total IHF power for the rear speakers Four -Channel Synthesizer -Decoder -Rear -Amplifier -and - is 120 watts (continuous power per channel is 40 watts at Control -Center combinations that transform standard two - 4 ohms, 33 watts at 8 ohms), with TH or IM distortion below channel stereo totally. The only other equipment you need 0.5% over a power bandwidth of 20 to 40,000 Hz. In its own is another pair of speakers. walnut cabinet, the QS500 sells for $279.95. You can decode any compatibly matrixed four -channel broadcasts or recordings and reproduce them in four authentic channels. You can detect the ambient signals An alternate four -channel miracle -maker is the modest present in most two -channel recordings or broadcasts and but well -endowed QS100, with total IHF music power of 50 propagate them through the rear channels. In Sansui matrix- watts (continuous power per channel of 18 watts at 4 ohms ing, the exclusive phase -shift technique prevents the can- and 15 watts at 8 ohms). In a walnut cabinet, it sells for cellation of some signals and the change in location of $209.95. _ others that occur in many matrixing systems. And the 'exclusive phase modulators restore the effect of the live sound field. You can plug in a four -channel reel-to-reel or cartridge deck or any other discrete source. In the future - if you should have to - you can add any adaptor, decoder or what - have -you for any four -channel system for disc or broadcast that anyone's even hinted at. And a full complement of streamlined controls lets you select any function or make any adjustment quickly and positively.

SANSUI ELECTRONICS CORP. Woodside, New York 11377 Gardena, California 90274 SANSUI ELECTRIC CO.. LTD., Tokyo. Japan Sansui Audio Europe S. A.. Antwerp, Belgium CIRCLE NO. 36 ON READER SERVICE CARD

FEBRUARY 1972 69 JI ANT T2 T3 V2 6BJ6

CI i 470pF

C2 .OIuF RI R2 R6 100K 6 611 IK

C24 .2PF)

R17 R16 1011 47011

D2 S2 + + STANDBY C23A T 30yF 70pF 117 VAC I

ALL FILAMENTS

PARTS LIST C20,C21-150-pF, 500 -volt disc ceramic ca- C1-470-pF, 500 -volt mica capacitor pacitor C2-C.5,C11,C12,C16-C19 0.01-µF, 500 -volt, C22 -0.01-µF, 400 -volt capacitor disc ceramic capacitor C23-Dual 30-µF and 70-µF, 150 -volt elec- C6 -0.02-µF, 400 -volt capacitor trolytic capacitor C7-C10-25-280-pF compression trimmer C24 0.2-µF, 200 -volt capacitor capacitor DI-Signal diode (14V34A or similar) C13-150-pF; 500 -volt silver mica capacitor D2-600V. 750mA rectifier diode C14-500-pF, 500 -volt silver mica capacitor JI-Coaxial connector C15 -0.02-µF, 500 -volt disc ceramic capacitor 12-Phono connector

plate and screen voltage on the tubes. Con- one of two ways: if you have a well -cali- nect an audio cable from 12 to an audio brated oscillator that tunes to 160-190 kHz, amplifier. The first adjustment is that of things will be simplified; or if you have T6, the oscillator coil. This can be made built the companion transmitter, you can by using a conventional BCB radio in close use it. In either case, connect a VTVJM proximity to the receiver. Assume you want across C6 (in the age line) with the nega- to tune to 175 -kHz. Add this to the i -f tive lead to the line. Now with the appro- frequency (455 kHz) and the result is 630 priate long -wave signal injected into the kHz. Tune the BC13 radio to 630 kHz and antenna circuit, you should get some indica- slowly adjust the slug of TO until you hear tion on the meter. Adjust C7, C8, C9, and the signal from the oscillator. Lock the TO CIO for a maximum indication. Then adjust slug with a jam nut or a drop of cement the slugs of T1, T4, and T5 to further in- on the threads. crease the meter indication. You may have The other adjustments can be made in to decrease the signal generator output or

70 POPULAR ELECTRONICS Including Electronics World 1 4 DI V3 V4 IN34A 66E6 6BJ6

1 C15 .029F L L

R7 27K 150 pF 1 C13 .019F I.OIyF 150pF J2 AUDIO OUT

/ C21 CI4 15opF C22 500 RO R9 RII R12 RI4 .OIyF pF 10K IK IOOK 6611 IK

C6 Fig. 1. Schematic and parts list for the low -frequency tuner .02yT are shown here. Although transistors could have been employed in the design, readily available vacuum tubes were chosen. Note that two r -f stages (V1 and V2) were used in design because the low power of the transmitter requires a very sensitive tuner. The converter stage is V3, and V4 is the amplifier.

RI,R4,R10-100,000-ohm, Y2 -watt resistor T2,7?-267-kIIz miniature i -f transformer R2,R5,R11-68-ohm, 1/, -watt resistor (Miller 12111 or similar) R.3,R6.R9,R12 1000 -ohm, '/2 -watt resistor T4.T5-155-kIIz miniature i -f transformer R7 -27,000 -ohm, 1/2 -¡watt resistor (Miller 12Ci or similar) R8 -10,000 -ohm, i6 -watt resistor TO Oscillator coil aleissner 1.4-1028 broad- R 13,R 14-1-megoh nr, 1/2 -watt resistor cast type R15-1-mego/rm, audio taper potentiometer T7-Transformer; secondaries: 125V at with switch Sl 50m.4 and 6.3V at 2A R16 -470 -ohm, 2 -watt resistor 1'1,1/2J'4-6BJ6 tube R17-10 -ohm, 1 -watt resistor V3 -613E6 tube R18 -10,000 -ohm, 2 -watt linear taper potenti- Ali.sc.-Chassis (Bud AC406 or similar), 7 - ometer pin miniature tube socket (4), knobs, ter- R19 -100,000 -ohm, I -watt resistor minal strips, ground lugs, rubber grom- SI-Spst switch on R15 mets, line cord, mounting hardware, short S2-Spst slide or toggle switch length of #98 enamelled wire for TI, short TI-TV width coil, 0.5-5 mlI (Miller 631.3 or length of thin coaxial treble for antenna similar) connector.

Fig. 2. This view of the top of the tuner shows how components were arranged on chassis for the prototype.

move the transmitter farther away to keep from overloading the receiver.

Operation. With the low -frequency tuner properly aligned and with a long antenna connected to it, adjust the audio gain (R/5) for a comfortable level and operate the r -f gain control (R18) so that the received signal does not overload the receiver. To use the transmitter and tuner together, 12 V2 52 T3 I RIO you can interlock the standby switches.

FEBRUARY 1972 71 "He's a good worker. ,Im I'd promote him right now if he had more education in electronics."

Could they be talking about you?

Home You'll miss a lot of opportunities if you try to get along full-time job and family obligations. But CREI in the electronics industry without an advanced edu- Study Programs make it possible for you to get the cation. Many doors will be closed to you, and no additional education you need without attending amount of hard work will open them. classes. You study at home, at your own pace, on But you can build a rewarding career if you supple- your own schedule. You study with the assurance that ment your experience with specialized knowledge of what you learn can be applied to the job immediately. one of the key areas of electronics. As a specialist, CREI Programs cover all important areas of elec- you will enjoy security, excellent pay, and the kind of tronics including communications, radar and sonar, future you want for yourself and your family. even cable TV engineering. You're sure to find a pro- Going back to school isn't easy for a man with a gram that fits your career objectives.

72 POPULAR ELECTRONICS Including Electronics World ..

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FEBRUARY 1972 75 Product Test Reports

ADVENT CASSETTE TAPE DECK To disengage power from both the motor (Model 201) and electronic circuits, a separate switc (A Hirsch -Houck Lab Report) must be operated. The PAUSE lever, when pulled toward the user stops tape motion instantly without dis- engaging the recording interlock. Upon re- leasing the lever, tape motion resumes without the perceptible initial "wow" that is characteristic of most other recorders. Pull- ing the PAUSE lever slightly to the right locks it in place; a slight push to the left releases it instantaneously. A separate RECORD button must be depressed simultaneously with the PLAY button to set the deck to the recording mode. A red light comes on when the deck's electronics are ready to record. The fast -fore and and rewind system in the 201 is unique. A spring -loaded lever which is normally centered is pushed to the The Advent Corp. Model 201 cassette left or the right to move the tape rapidly in tape deck is an improved and considerably the indicated direction. It does not latch modified version of the company's original and, as a result, must be held in position Model 200. It has built-in Dolby Type "B" during the entire winding operation. I-Iow- circuits to provide a noise reduction figure ever, the deck has by far the fastest high- of from 6 to 10 dB. Like the Model 200, the speed tape movement of any we have seen 201 has switchable bias and equalization for in a cassette deck; so, the non -latch feature standard and the new chromium -dioxide poses no hardship. tape formulations and an illuminated VU The cassette snaps into an open well that meter which can be used to display individ- keeps it completely visible during operation. ual channel signal levels or be left to indi- An EJECT lever, when activated, pops up the cate the higher level of the two channels. cassette vigorously. When the end of tape The Model 201 cassette deck, in its wal- travel is reached, the motor stalls and the nut base, measures 1314' x 9'4" x 41" and entire transport shuts down and disengages weighs only 131 pounds. It is priced at mechanically to prevent the formation of fiat $280. An optional external microphone pre- spots on the rubber pressure wheel. amplifier can be obtained for an additional The inputs and outputs (for line level $20.00. sources only), together with the output level control, an 18 -volt do jack, and a recording - Description. The Model 201 deck, un- level test button for calibration of the Dolby like most cassette units, is made entirely in system are recessed into the left side panel the United States. Of the walnut base. There are no microphone Pushing the PLAY button powers the motor inputs, but Advent offers an optional exter- and the electronic circuits. The STOP button, nal microphone preamplifier which plugs when activated, shuts oil the transport but into the 18 -volt de jack to obtain its power. maintains power on the rest of the system. On the top panel of the deck are two in -

76 POPULAR ELECTRONICS Including Electronics World truly

25 -MHz BANDWIDTH remarkable DELAYING SWEEP

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10 -mV SENSITIVITY Í- A590 FOCU9 RRRuANCE CTEr.EpulPrnENT DUAL TRACE & G'{ OW J SIGNAL DELAY LINE l:Y%alAetE TMIE/CM- - w1 B f' 51'''/,1,,,.i. ALL FOR ONLY .. .

CH1 j =YARIABLE X975 = TtYE/CM

VARIANCE VOLTS/CM J9' The new Telequipment D67 _ ... ' Oscilloscope offers the .0011,10.1 14' R z . performance you have always ] Olít .07 InPu- 2 ; >411> desired at a price that is several 4 orr or. 9 *1.1.5(1G: hundred dollars lower than any 1 zT. our other comparable model. w 0100 CH2 ¿Mt, OR .1` / e TELEC]LFNAENT i!Y/' osaposeo Ppe 067 ¡ In addition to its impressive array " of specifications, the D67 has Iv ,, other features not usually found in low-priced scopes: regulated power supplies, FET inputs to keep vertical trace drift to a minimum, fully solid-state design resolution analysis of pulse to improve reliability, transistors sequences. And if some of the Telequipment Oscilloscopes are in sockets to make servicing pulses are jittery, that won't be marketed and supported in the easier and faster. a problem because the delayed U.S- through the Tektronix network Bright displays are obtained by sweep can be triggered. Those of 56 Field Offices and 32 using 10 -kV high voltage on the who have a need to view Service Centers. The instruments rectangular 5 -inch CRT which has television signals will be pleased are warranted against defective a big 8 x 10 cm display area. with the D67's ability to trigger parts and workmanship for one at TV field and line rates. year.. For more information call A wide range of sweep rates your nearby Tektronix field from 2 s/cm to 0.21,s/cm (40 ns Even if portability is not a prime engineer or write: P. O. Box 500, with X5 magnifier), delayed sweep, consideration, you are certain Beaverton, Oregon 97005. 3% accuracy and 14-ns risetime, to like the D67's light weight- make the D67 ideal for high it weighs only 25 lbs. Telequipment Oscilloscope prices start as low as $245.

U.S. Sales Prices FOB Beaverton, Oregon

TELEQUIPMENT <9> TELEQUIPMENT a subsidiary of Tektronix, Inc. CIRCLE NO. 44 ON READER SERVICE CARD

FEBRUARY 1972 _ 77 »., It:,-c t í' S;i,1 a?! t ._.--.- l . ti : t .ii':. : 1 ' .- ... } L'jt... : _.,-: -t', 4 .{~: : ,..( l kY- I S : n z !¡ .__ ? _ ii a .. _. : I - 1 AOVENT201.: ... ' áT -_.I f ;tf }I.`.._-_ 3_ _.. _ -

.^?fS'.:,;:: I,t. f..:i¡irt*-tzrt.,.. l t'M.i$== w' a..- -. t ü. ?, ,, ..!.U, RECORD/IL-.-_:: `.... '4:, .1 . i '`.: , PLAYBACK RESPONSE - s.. , ' _.. :i¡:.1tÑ . i j j 1I -t t 4 t:-:r::.. i:- I. 3M ER/BT :-. _ 'll~ :i::-;.:._-r~~t- :.it (-30dB) , >~ s . .. N0 DOLBY =E i.,..i_ `i_ . 1_ .Ir-_ iY tÍt_ -i_i 3xt.42..:4-:::::--::-....:-t ...... 7ili_., x: ,...... _ ...... ';i. i! 1 _-:Y ; -«. r.... . i ^ t i É :: ,¡ ...... ' 31..',,.. ..._}lii?:¡r- Ill -.4.11'.,.:_ _,.. :: .:. ' __ r...... " 1:: iileí i':.t' ..... __1;1'.:_ {t.':::::::,',:.- ... . jJli._f,t ..Ith`:-i?: .:tll:. ..- !., ._. .... ! t'.!t:ii:.::^1::'...,..._ .. ..::ll...... ::. ...I_:'!::f::::...:i:t'..:!_ .##,.,. .... ic ./;...... _.?:(í ... _ ! i H :-i H1,:.. : ' -_! - ..í! ,...Ill . i.l....-: ...... 1` . _l...... 5E,.1...- _ _ -- i7.'I _.... -::#m -.:' - ...... -.'1: 'St .. ..._ ...I ..._..' ...... _... . : ...... i;_._^ ._ ...... _ I ... ..;. . _ .t;r..._rli:!-.1.:.--!-i-,-`If t -, ...... :_ - - :-:i...... _...... __-__:_:.... :. .._: -z 20 ttri 00 FREQUENCYooHz

.. li:{-'i:`r.??1 =if4.:.u.l .:i`11-.----71±,--1 }'' fii ..1{ ::.'.'..-1.;`_-{.. _.. .. -;_ :ur i il:^ }_,.._.z -L:....._----L`:ts :I 'a:a::: -i ..nf-. - l'.1-7.:,.111...,:::4. i;' :1!. _ f,i.:! i{:i =_ . : »7 ?t ? . _ _. j ? -i i "1_.-7-:: c^:: .'` .'t i. 1_ _.`' t.. '? - t 11 11. .. t? t'--;tr. -; f1 2 i . ' , ADVENT 201, ( 7 . ,;. '.., Pl :lti"._ f: . i:! ;iil. : t:: :LL'- r.ffiz4 _:,t: .. ::::... =_'r Í' j....*?1 i :1 : .x: 1=7-77771-_--11 .:!:7'1,! ... ` t,fl -_-.-::-- t-:..::.. ,.'i 11 PLAYBACK RESPONSE -{ ii.V'ui;üii;i::= r-:: iii:' F^ -,_._:.c... :: I.._..-_. _ ii --;!üü':- ..-- BASF TAPE C -- - t::: t...... h'',. - : , ,:: ,;: . . ---,'1::-.L.1-:. -- ? I t :a:__-. H4411" ply., i . -:-.r _li z.t(:.:-IF: tkiüii'ü.= ü_... i?? _ 1; -:: :!a 7r i1, i ? 1 :. ::--: ,.-: ::1:;.::: . ..--11.11 a' ,-::, a, :: 1 .:.... .7.... J-1- .. . H.dS.. -::_ j:::Í_: '¡:j.P":.:. _.[vL'.. ..._... ` -{ St:::IY-^ - y3. :f .... :-- i.. .: .. {-- .,. _.... ._.. ?:.'.[i_r1 -, _ :;?i .. i:::: itcW . .1: _ t::....li'd.. . .. _.- .. _=3- `,. : _dl i i, , ._...... _-_.. - .<_ . .-]'`C:._:.. ?1¡: It ... _...... _ ._ ...... ;,'yi;?!fj::-- ...... _...... _._ .c_:.:. ...:::..._- _ - _1t iit'k? t-1., i::7t i1if._...- -:"1.-1_=-. Tt f",'=,: - , idod 0000 20000 FREQUENCY. Hz Record/playback (top) and playback only (directly above) curves show the Ad- vent 201 tape deck's very flat frequency response over range of 50-10,000 Hz. put level controls and a master recording Dolby circuits switched in, the S/N ratio level control which operates both channels improved to 54 dB. And, using Advocate simultaneously. Near the controls are a Crolyn tape, it was 53 dB without and 57 rocker switch which can be set for stereo or dB with the Dolby circuits switched in. mono recording and three lever switches. Distortion at 0 VU was 1.9 percent and One of the lever switches is used to turn on did not reach the standard 3 percent refer- and off the Dolby circuits. Another connects ence level until a +3 -VU signal was applied. the VU meter as desired. And the third Since the signal-to-noise ratio of a tape re- switch is used to optimize the recorder for corder is usually expressed relative to the 3 either regular or chromium -dioxide tape percent distortion level, the Model 201 pro- formulations, adjusting both bias and play- vided a 60 -dB S/N ratio with chromium - back equalization. On the underside of the dioxide tape-a truly remarkable figure for Beek are screwdriver controls for adjusting the narrow track and low 134-ips tape speed. bias and Dolby recording levels. It is equalled by few 71_-ips reel-to-reel recorders. Test Results. In our lab measurements, the overall frequency response on record User Reactions. In listening tests, the and playback, using 3M EH/13T tape, tested Advent Model 201 cassette deck was as im- out at 31-15,000 Iiz -x-1.5 dB. \Vith other pressive sounding as its bench measurements tape formulations, minor differences in high - suggested. Noise was inaudible at even very frequency output can be expected. Using high volume levels. The buyer of a 201 re- Advocate "Crolyn" tape, frequency response ceives a demonstration cassette recorded on was extended slightly (31-15,500 Hz ±2 his purchased deck from a 15-ips master dB). Playback response with a BASF test tape. The only hiss we heard when playing cassette was 100-10,000 Hz ± 1 dB and, at this demo cassette-and then only at very 40 Hz, was +3.5 dB. Unweighted wow and high levels-was transmitted to our record- flutter checked out at 0.17 percent. A 0-VU ing from the master tape itself. recording level required a 31 -mV input, de- The overall sound quality obtained from livering a 530 -mV output level. the Model 201 can be described only as The signal-to-noise ratio when standard superb. This deck sounds as good as most tape was used was 48.5 dB, referred to 71/2-ips reel-to-reel recorders selling in the 0 VU, the standard Dolby level. With the rarefied $500 and higher price range. Flutter,

78 POPULAR ELECTRONICS Including Electronics World usually the weakest link in a cassette system, It has lower distortion than most reel-to-reel could not be heard from the Advent 201 recorders we have tested and a S/N ratio cassette deck. matched only by a couple of the very In summary, the Advent Model 201 cas- best reel-to-reel machines. In addition, it sette deck is among the finest such mechan- is simple and convenient to operate, and its isms we have tested to date. Its frequency fast forward and rewind speeds make acces- response is more than equal to the task of sible any portion of a C60 cassette in less dubbing from discs or FM tuner/receivers. than 45 seconds. Circle No. 75 on Reader Service Card

EICO 4 -CHANNEL STEREO ADAPTER quadraphonic sound. An extra stereo amplifier is not needed since the Sound/4 is (Sound/4 Model EC -4700) compatible with all existing 2 -channel equipment and program sources. The EC - Now that quadraphonic sound is making 4700 simply accepts the two present speaker an all-out hid for a permanent place in the outputs and mixes them to deliver the two hi-fi market, a number of 4 -channel stereo conventional front outputs plus the am- converters are making their appearance. bience signals required for driving the two The latest such entry is the Eicocraft Model rear channel speaker systems. EC -4700 "Sound/4" stereo adapter made The adapter can be used with 4-, 8-, by Eico Electronic Instrument Co., Inc. or 16 -ohm amplifier outputs. A small book- Unlike the systems which use active cir- let provided with the unit explains the cuitry to recover the ambience information complete setup, including the very easy present in most two -channel stereo sources, method of properly balancing the four the Sound/4 employs a passive network speaker system outputs. that requires the addition of only a pair of The Sound /4's appr xich to proving the speaker systems for the rear channels to value of quadraphonic sound was tested convert any existing stereo system for with a conventional good -quality stereo The best of two worlds... Short Wave Listening Communications Radio

4~1

"-1 1 7 = Drake rü í'. -Fe . Drake ($J MODEL 1.1 MODEL -5 -g mV i SW 4-A SPR-4 International Shortwave Programmable Broadcast Receiver Communications Receiver Precision tuning dial eliminates guesswork, permits Programmable to suit any interest: SWL, Amateur, Direct Frequency Dialing on SW and standard AM Laboratory, Broadcast, Marine Radio, etc. All solid Broadcast Crystal lattice filter for adjacent station state Direct Frequency Dialing: 150-500 kHz plus rejection and good AF response Dual conversion any (23) 500 kHz ranges, .500 to 30 MHz FET Solid state AF output S -meter Preselector gives Circuitry Linear dial, 1 Id4z readout 3 band- superior sensitivity by peaking antenna and RF stages widths: 0.4 kHz, 2.4 kHz, and 4.8 kHz for: CW, SSB, Crystal -controlled H. F. Oscillator stability Am- AM Power: 120 VAC, 220 VAC, and 12 VDC Cry- for LW, BC and seven SW bands. pified AVC constant AF output. $299.00 stals supplied $499.95

540 Rüchard StreetMiamisburg, R. L. DRAKE COMPANY L DRAKE° Ohio 45342

CIRCLE NO. 15 ON READER SERVICE CARD

FEBRUARY 1972 79 system to which had been added a pair of low-cost, limited -frequency -response speakers for reproduction on the rear channels. The resulting sound was quite pleasant. The added "ambience" effect from the two speakers to the rear certainly added a new

dimension to an already good stereo setup. LEFT i \Ve conclude that the use of rear speakers that were as good as those in the front GNO would have vastly improved our already pleasant test setup. GNO The EC -4700 is available in both kit a1GHT . pK3HT and wired versions. \Ve received the former. It went together quickly and without a hitch. Once the innards are assembled 4 3 and wired, the entire adapter tucks away REAR ,AMP FRONT into a small plastic box which can easily 48» 41111. be concealed behind almost any amplifier or receiver. And for maximum ALL coo convenience. s Ú It J - . Eico provides, with their Sound, 4's, all SPKR 4 -CHANNEL" STEREO ADAPTOR the necessary speaker -to -adapter cables LfiEAR STEREO needed. EICOCRAFT Model EC4700 The Sound/4 is priced at $9.95 in kit form, $19.95 factory -wired.

Circle No. 76 on Render Service Card

MIDLAND SSB/AM TRANSCEIVER meter, external -speaker jack, and public- (Model 13-873) address facility.

Technical Highlights. A total of 31 transistors (three of which are FET's), 65 diodes, and one IC are employed in the transceiver. Except for a common front end (r -f stage, heterodyning mixer, and frequency synthesizer), there are separate receiving sections for SSB and AM. Single conversion to a 7.8-MIIz i -f is used for SSB with selectivity and sideband selection The Midland Communications Co. Model obtained with an 8 -pole crystal -lattice filter 13-873 Citizens Band transceiver provides that provides a 350 -2700 -Hz bandpass and operation on all 23 Class D channels us- an adjacent -channel rejection and unwanted ing single sideband or AM. It thus pro- sideband suppression of 60 dB. vides all the advantages of SSB operation, Dual conversion is used for AM: with still while permitting communication in the 7.8 \IIiz i -f converted down to 455 the AM mode with stations not equipped to kHz through a ceramic filter, providing a handle SSB traffic. 50-dB adjacent -channel rejection figure. Im- The Model 13-873 is a solid-state CB age rejection in either mode is 70 dB. transceiver capable of a 10 -watt peak in- A performance figure that points up put power level when operated in the SSB an advantage of SSB over AM is that of mode. Either upper- or lower-sideband op- the weak -signal sensitivity, which on SSB eration can be used, providing 46 working is 6 dB better than on A\I as indicated by channels instead of the 23 channels to which the comparative measurements of 0.25 µV AM is limited. The carrier input power on SSB and 0.5 µV on AM for 10 dB S+N N. for AM is 5 watts. The squelch operates in both modes The transceiver has adjustable squelch, with an adjustable sensitivity of 0.25-750 fine tuning control (clarifier), noise blanker µV. The noise blanker is most effective for superior noise suppression, dual-purpose for SSB where it suppresses impulse noise

80 POPULAR ELECTRONICS Including Electronics World by at least 40 dB. An excellent age setup are used in combinations of two for produc- maintains a relatively uniform a -f output ing different frequencies in the 19.2-MIIz measured as a 4-d13 change with an input - ranges as required for heterodyning to each signal change of 100 dB (1-100,00 µV) CI3 channel and the particular sideband. on SSB and of 80 dB (10-100,000 11.V) Three r -f amplifiers, including the power on AM. amplifier, raise the SSB signal level to a A little over 100 µV is required to obtain peak -power output level of 4 watts when the an S-9 meter reading. The meter also dou- transceiver is operated from a 13.6 -volt do bles as a relative output -power indicator sot tree. during transmit. In either case, it shows a The unwanted sideband and the carrier steady reading in the AM mode, but xvith suppression were both found to lie 60 dB. SSB, it deflects tip and clown according to The distortion products \vhich are primar- the modulation level. A transmute indicator ily indicative of the possible broadness of lamp responds in a similar manner. the signal and the maintenance of good For SSB transmissions an initial 7.8 -MHz tin Wall tecl-siclebancl suppression at maxiluUM carrier signal is obtained from a crystal - output were at least 22 dB down. This is controlled oscillator that also serves as a about pair for the course with transistors. BFO to provide carrier re-insertion on re- For AM operation. the synthesizer's ceived SSB signals. The filter method of output signal is heterodyned with the SSB generation is employed, using a bal- 7.8-\1IIz carrier oscillator signal (other- anced modulator where the carrier is nulled wise used for SS13) to provide an on -chan- out. This leaves suppressed -carrier double- nel AM carrier sig lal that goes to the sideband signal, one sideband of which 's same r -f amplifier as used for SSB. In subsequently rejected by the same 7.8 -MHz this case, both the driver and p.a. are filter used in the SSB receiving section. collector -modulated by the a -f output stage The resulting SSB signal is converted to of the receiver. On AM, the transceiver put the CB range by heterodyning it with oscil- out a 3.5 -watt carrier with modulation lator signals from the frequency synthesizer. limited to 85 percent. The synthesizer employs 14 crystals which When used for SSB,. the receiver must ` the tape that , .I turned the cassette into Until TDK developed gamma ferric oxide, cassette recorders were fine for taping Iec:ures, conferences, verbal a high-fidelity . memos and family fun-but not for serioús high fidelity. i T .ccA.marn-K c-1/o.o

medium ° Today you can - choose among EZ 14' 1. high-gjality E miiamERU! A _. stereo cassette cecks, .E 20 10 -..n1112.10n0.111,7 "."» ".» The new magnetic oxide used ii TDK Super Dynamic tape distinctively differs from standard formulations in such El "'OK -,`:s 50 C-SC) important properties as cosrciye torte, hysteresis -loop . H L.. _ ---'- squareness, average particle Iengjh (only 0.4 micron!) and particle width/length ratio .These add up to meaningful ®- performance differences: response capability from 30 to t 20,000 Hz, drastically reduced background hiss, higher output.level, decreased distortion and expanded dynamic range. In'response alone, there's abcút 4 to 10 db more TDK SUPER DYNAMIC (SD) TAPE output in the region above 10,0001íz-and this is immediately evident on any cassette recorder, including ° older types not designed for high uertormance. There's a difference it clarity and cr spness you can hear.

° j Available in C6IISD and C9OSD lengths. TbK. ELECTRONICS CORP. LONG ISLAND CITY, NEW YORK 11103 CIRCLE NO. 43 ON READER SERVICE CARD

FEBRUARY 1972 81 be tuned to the exact frequency of the crystals must be held closer than usual, so transmitted signal; otherwise, the signal that the clarifier adjustment will not result in at the receiver will have an unnatural voice operation outside the legal tolerance of sound. This is handled by the fine-tuning ±0.005 percent. With the Midland unit, (clarifier) control which shifts the fre- the maximum deviation at the extreme quency ±550 Hz. It alters both the receiver settings of the clarifier held within 0.0022 and the transmitter frequency so that, when percent on all channels. an SSB signal is properly tuned in, trans- Although designed for mobile service, missions can be made precisely on the same the transceiver can also be employed as a frequency. The end result is that inter- base station when powered by an acces- communication between two or more sta- sory ac -powered 12 -volt dc supply. tions may be held right on frequency with- The Midland Model 13-873 CB trans- out the need for constant retuning. ceiver, including push -to -talk microphone, Since the transmitter frequency is con- do power cable, mounting bracket, and hard- trolled as described, the tolerance of the ware sells for $369.95. Circle No. 77 on Reader Service Card

KOSS RED -DEVIL STEREO HEADPHONES (Model KRD-711) (Hirsch -Houck Lab Report)

Stereo headphones are available in many styles and are marketed over such a wide t, price range that many people have difficulty in deciding which ones to buy. As with i most products, there is a rough, but not rigid, relationship between list price and quality in the headphone market. But the price "spread" among stereo headphones is so great that most buyers settle for some medium-priced unit which they hope will prove to be satisfactory. The Koss Electronics Inc. Model KRD- 711 "Red Devil" phones are one example of good quality units available at low cost. Falling near the lower end of the Koss price scale, they nevertheless have many of the sonic qualities of much more expensive We made measurements of the frequency phones. response and impedance of the Red Devil, The earpieces are a bright red, molded using a homemade coupler to simulate the plastic (hence the name Red Devil). The human ear cavity. The frequency response, headband. molded from red polypropylene measured in this manner, is usually more plastic and fitted with a foam -padded top, irregular than it seems to be in a subjective is a simple but comfortable design. The evaluation; but it does tend to show trends removable ear cushions are of neoprene in response. foam construction, fitting snugly but com- The output in the range from 20 to 1000 fortably over the ears and effectively ex- Hz was very smooth and uniform within cluding external noises. ±3 dB, attesting to the effectiveness of the Because of its construction, the Red Devil ear seals. It rose at higher frequencies (with is unusually lightweight, 12 ounces (less the expected irregularities due to the cou- cord). The coiled cord extends to 10 ft and pler) and was still very strong at 17,000 is fitted with a standard stereo phone plug. IIz-which is well above the 15,000-Hz cali- The nominal impedance of the Red Devil is bration limit of our microphone. 20 ohms per channel-which means that The measured impedance was higher the phones can be driven from the speaker than the specified 20 ohms, averaging about outputs of any amplifier in which the aver- 280 ohms at the low and middle frequencies age program level does not exceed 5 volts. and about 500 ohms at 20,000 Hz. Sensi-

82 POPULAR ELECTRONICS Including Electronics World i /- : ;,';=.j; . '.. ran _L

p , u c " «ice .°

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Now you can get information on Air Force opportunities by calling this number anywhere in the country-toll free. And it can be a real hot line as far as your future is concerned. For instance, any job you're trained for, any skill you learn in the Air Force will he valuable to you in or out of the service. Air Force skills are lifetime skills. Right now, your Air Force Recruiter has a special listing of select jobs that he can guarantee to you before you join up. No more chance, just choice. Give the Air Force a call. It could he the most important call you ever made. (^ In New Jersey call 800-962-2803.) Find yourself in the Air Force.

FEBRUARY 1972 83 tivitv, as with most stereo headphones, was top -of -the -line Model PRO-4AA phones more than adequate for high -volume listen- made by Koss. Apparently, the Koss people ing with any amplifier. At the very high have engineered the Red Devil for low- level of 114 dB, distortion was only 1.0 cost production without sacrificing quality. percent at 400 Hz. This makes the KRD-711 one of the best In listening tests, by itself and in com- sounding stereo headphones at or near their parison with a number of othe phones price of $29.95. (Note: Koss is currently (most of which were more expensive), the offering a jet-black version of these head- Red Devil proved to be one of the best phones as their Model K-711 at the same sounding of the group. In fact, its sound price. Their performance and construction quality was remarkably close to that of the are identical to those of the Red Devil.) Circle No. 78 on Reader Service Card

SIMPSON DIGITAL VOLTOHMMETER whi e the other three ranges drop down to (Model 460) 10 megohms each. The five ac voltage ranges have an input impedance of 1 megohm at 150 pF. The five ac and do current ranges have a 200 -RA to 1000-mA (one ampere) capability, all with 3 -ampere overload protection. Of the six resistance ranges, the 200 -ohm range uses 2-mA test current, the 2K range uses 200 RA, the 20K range is 20 ttA, the 200K range is also 20 RA, the 1-megohm range is only 2 µA, and the 20-megohm range is 200 RA. All together there are a grand total of 26 of the most useful test ranges. The non -blinking 31f2-decade readout display uses the popular single -plane seven - While examining a large pile of brand- segment readouts that are easy to read. Be- new test equipment, some of which we first cause the 460 has automatic polarity seeking, previewed at the National Electronics Week either a "4-" or "-" sign will be displayed show held in Miami Beach last year, we on the left side. dependent on the polarity happened upon the Simpson Electric Co. of the voltage applied to the probe tip. Model 460 portable digital VONI. Its price Measurement accuracy is also high. De tag of $395 seemed a bit steep, but we did voltage measurements are within 0.1%. ac not let that deter us. In fact, it made us is from 0.5% between 40 Hz and 10 kllz curious to find out just why almost $400 and 1% from 10 to 20 kHz. De current was asked for the instrument. measurements are within 0.2%, while ac Having used an elderly Model 260 meter - current is measured within 0.7% of the read- movement VOM made by Simpson in our ing. lab for quite a number of years, and know- Resistance measiu-ements are within 0.5% ing that it had proven to be a very good except for the 20-megohm range which is meter, we expected much of its 1971 rela- 1%. All of the above readings are {- 1 digit. tive, the Model 460. After using the 460 for Overrange capability is 150% to protect the a while, we feel that it lives up to the rigid instrument from mishaps. standards set down by its now classic relative. Special Features. Having used digital multimeters before, we were surprised by Operating Ranges. The ranges of the new this one on a couple of points. First, it con- DVONI cover just about any need you are tains its own rechargeable nickel -cadmium likely to encounter on your testbench. There batteries that can provide up to seven hours are five de and five ac voltage ranges from of truly portable operation. When the 460 is 200 mV full-scale to 1000 volts full scale. plugged into the ac power line, even while The 200 -mV range has a 100-megohm input it is being used to make measurements, its resistance, the 2-V range has 1000 megohms, internal batteries are automatically being

84 POPULAR ELECTRONICS Including Electronics World charged. Second, this is the first digital instrument we have seen that also contains an analog meter (I)z inches, edgewise mounted) 4 -CHANNEL that displays peaks and nulls at a glance during alignment procedures. (Try that on most other DVO\I's and see how difficult nulls and peaks are to locate.) SOUND! As an added bonus, the analog meter is ADD IT TO YOUR STEREO SYSTEM also used in conjunction with a front -panel pushbutton to test the battery at any time. IN JUST ABOUT 15 MINUTES! The meter scale is suitably marked. Finally, -Tj<

LEADER ELECTRONIC OSCILLOSCOPE SWITCH (Model LS -5) Only

ELECTRONIC 6995* SWITCH Il teIICNYe PATES IRNH Complete Add -On System Quatravox,,, 4 -Channel Synthesizer CM -2 Two MC -500 Bookshelf Speaker Systems In Oiled Walnut Cabinets ;. Nationwide Supermarket of Sound LEAO¢q Ask for

FREE AND ALLIED RADIO STORES If you work with an oscilloscope, you are Catalog! It A TANDY CORPORATION COMPANY already aware of how important it is as a 2725 W. 7th St. Ft. Worth, Texas 76107 piece of testbench equipment. You know * PLUS APPLICABLE SURCHARGE/REVALUATION CHARGE. also how much of a problem it can be when CIRCLE NO. 2 ON READER SERVICE CARD

FEBRUARY 1972 85 +9V 05 R2 POSITION

SCOPE NPUT SYNC F TO 03 SECOND CHANNEL SI DC AC =

RI h GAIN

OUTPUT TO SCOPE

L- FROM OTHER CHANNEL

One channel of the dual system. FET stage Q2 is protected by a diode -connected bipolar while switching takes place in the common transistor amplifier Q3. you try to "see" what goes on between the switch also provides a trigger pulse (de- input and output of a particular circuit. rived from the signal on channel 1) to lock Because of changing signal levels and the the external oscilloscope to the viewed need for sometimes constant readjustment signal. of the scope controls, it becomes a bit tedi- The partial schematic shown here gives ous to keep swapping the scope leads be- the basic operation of one channel. (The tween test points. two channels are similar.) After passing Then, too, when working on digital through the ac -dc selector switch, the signal equipment, it is necessary to know the re- is passed to gain control R1 and the lationships between the various pulses run- gate of FET input stage Q2. Diode -con- ning through a particular circuit. There nected transistor Ql protects the sensitive is no convenient way this can he determined gate against accidental overvoltage which when using a single -beam scope. could puncture the gate junction of the Now, with the Leader Instrunlenls Corp. FET. The output of the FET is coupled to N'lodel LS -5 electronic switch, you can a conventional bipolar transistor amplifier, hook up test leads to both input and output Q3. The vertical position of the input signal points of a circuit, or between any two logic (on the scope screen) is determined by the points, and display both signals simultane- source bias of Q2, determined by the set- ously on a single -beam scope with the ting of position control R2. The output of capability of positioning each trace as de- Q.3 is made via emitter follower Q4, which sired on the scope face. This solid-state also accepts the switched signal from the switcher provides a choice of four switching other stage. frequencies- 1.5, 5, 30, and 50 kHz, to Transistor Q3 is switched on and off by avoid "breaking up" the displayed trace a square wave generated in a switched - regardless of the harmonic relationship speed multivibrator. The two outputs of between the input signal being viewed and the latter are arranged so that, while one the selected switching speed. stage is operating, the other stage is turned Frequency response is do to 300 kHz and off. The external scope then displays first 2 Hz to 300 kHz in the ac mode. Each one signal, then the other, at such a rapid channel has its own ac-dc selector switch. rate that they both appear to be on at one Input impedance is 100,000 ohms, and each time. The scope sync signal is taken off channel has a gain of two. Both gain and via FET stage Q.5, with this signal fed to a positioning controls are provided for each front -panel connector. of the two switched channels. The electronic The power source is a full -wave bridge

86 POPULAR ELECTRONICS Including Electronics World It's old enough to vote. You haven't seen one like it since 1954.

1 Now you've got to . ktt. service it. ; - 1, t ,., ' - ..J - -= r ; o z

No sweat. PHOTOFACTs gives you complete serv- The cost? A bargain either way. Photofact-of-the- ice data on 87,000 different radio/TV circuits ... Month Club members pay just $13.50 a month-a including Rip Van Winkle, here. S56.00 a year saving for the entire service package. Sams Photofact is the most comprehensive Radio/ And if you need a Photofact on Rip Van Winkle, TV/Audio circuit source in the world. Photofact above. the price is only $3. supplies complete service information on over 1. Ask your Sams Distributor, or ... 87,000 models produced since 1946-color and 2. Fill. out this coupon for membership in the b -w TV, AM and FM radios. stereos and record Photofact-of-the-Month Club service changers. Plus service data on auto radios and ... get data on up to 65 chassis tape players, CB radios, modular hi-fi and tape renew every month, delivered in 6 handy file folders plus "Bonus" corders. Quite a package! ... monthly certificate coupons toward a file cabinet of your And more data month, keeps coming. Every Photo - choice. fact produces new Photofact data containing easy - to -follow service information on up to 65 of the latest chassis. HOWARD W. SAMS & CO., INC. 4300 West 62nd St., 81K Indianapolis, Indiana 46268 This data includes the manufacturers' own printed PE 022 Please enroll me as a new member of the Photofact-of- board callout numbers, detailed circuits. photos, the-Month Club. I agree to pay S13.50 per month for my standard notation schematics, replacement parts membership and understand my subscription will begin with the 6 current Photofact Sets, plus the Photofact lists and descriptions, etc., etc., for each model. Index, free, to be delivered by my Sams Distributor. It'll save you hours of time and frustration. Narre And it's available in two ways: (1) Photofact-of-the- Business name Month Club members receive regular monthly de- Address City State Zip liveries of the latest data; (2) or you can purchase My Sams Distributor in whatever you need service data as you need it Sign here from your local electronic parts distributor. L CIRCLE NO. 35 ON READER SERVICE CARD FEBRUARY 1972 87 followed by a pair of transistor voltage workbench also incorporates a special regulators. mounting bracket to facilitate direct mount- Built with the usual high -quality mech- ing on almost any scope. The instrument is anical construction featured in all Leader 51" x 4" x 31", and we'ghs 3 pounds. It instruments, this excellent addition to any retails for 569.95. Circle No. 80 on Reader Service Card

JFD ALL -CHANNEL TV ANTENNA the TV receiver is included with the anten- (Stellar -2001) na. The power supply can be mounted via a pair of built-in tabs, or you can peel away the protective backing and firmly press the exposed adhesive surface against the back of your TV cabinet. A high signal-to-noise ratio is maintained by amplifying the signal directly at the antenna, properly matching the amplifier to the actual antenna, using an amplifier that has linear characteristics, and using reactive filters so that overloading the active Over the years, TV receiving antennas elements is virtually impossible. The combi- have been getting bigger and bigger. nation signal-splitter/power supply package The more sophisticated antennas sport doz- has provisions for both vhf and uhf connec- ens of rod -like elements and metalwork that looks like something out of a Baroque dream. With the introduction of the Stellar -2001, JFD Electronics Corp. is reversing the trend in antenna design. Instead of resem- bling the end product of a child's construction set, the Stellar -2001 has a futuristic spade shape that measures only 34" wide by 2731" long and a mere 394" thick. The antenna itself is not spade shaped; it is the all -plastic weatherproof shell enclosing the "antenna" that accounts for the wing -like shape. Aside from compact size and neater appearance, the great advantage of the Stellar -2001 is its almost nonexistent wind loading effect. Weighing only five pounds, the new vhf, uhf antenna can he installed almost anywhere by one person. It can he mounted flat against a roof, on the usual 1W' -diameter This look TV mast, new in antennas features or even inside an attic. All mounting a PC antenna and low -noise solid-state hardware, plus a liberal supply of weather- amplifier. Wind loading is very low. proofing adhesive that is used to seal screw entries through a roof, are supplied with tions to the TV receiver; another separate the antenna. output is also provided for feeding a second receiver. Technical Details. According to the peo- Coaxial cable (7.5 -ohm) is used between ple at JFD, the innards of the Stellar-2001 the antenna/amplifier and the signal -split - contain a large printed -circuit device that ter/ power supply. However, the splitter takes the place of conventional aluminum supply package's output is rated at 300 elements plus a built-in low -noise solid- ohms to provide the proper impedance state amplifier. Power for the amplifier is match to TV receiver input terminals. fed up the same coaxial cable down which the TV signal travels to the receiver. A small Use Tests. We installed the Stellar -2001 power supply that mounts on the back of on a short, stubby mast in the same area

88 POPULAR ELECTRONICS Including Electronics World as a far larger log -periodic antenna array. Switching hack and forth between the two antennas showed little, if any, difference POLY-PLANAR IS in signal quality. The real test. however, came with big-wind Doria \vhich hit the east coast last August. \Ve (and many of BUILT-IN SOUND our neighbors) lost aluminum elements from our log -periodic antenna and also had degradation in signal quality due to the ON A BUDGET. severe rain causing leakages in the antenna. Switching to the Stellar -2001, we found that the picture was perfectly steady and showed no signs of the violence nature was stirring outside. Although not a deep -fringe antenna, the Stellar -2001 provided satisfactory reception almost 50 miles away from the TV Walls, ceilings, doors, transmitting antenna complex. But more floors, closets-any

11 ;l important is the fact that this new antenna surface at all-become i has good looks-rather handsome. in fact- hi-fi speaker systems that will not begin to show aging for a very with Poly -Planar. -1 long time. Price of the Stellar -2001 is 875.00. It is also available as the Stellar -2001K, which THE SPEAKER YOU DON'T is identical but also includes 50 ft of 75 -ohm coaxial cable fitted with a weather boot, HAVE TO SEE TO HEAR. for $85.00. Both antennas, of course, include all mounting hardware, brackets, and The Magitran Company weather sealer, plus excellently written and 311 East Park Street Moonachie, New Jersey 07074 illustrated mounting and hookup instruc- CIRCLE NO. 31 ON READER SERVICE CARD tions. Circle No. 81 on Reader Service Card TccER MONEY -SAVING 1972 CATALOG FOR THE MAN IN ELECTRONICS 91 .,a +es TRIGGER'S GREAT SELECTIONS Send for this reliable buying guide to carefully selected: 1 Amateur Gear Stereo Hi - Out of Tune1 Fi Electronic Kits CB Radio Tape Recording I.. Electronic Parts Antennas Product Test Reports, January 1972. In Tubes Transistors 4 1 Tools Books Test Gear I our report on the Pioneer PL -12A Record t t',,s Count on TRIGGER for the ; 014615"f...---11--4451461:"- Player, two serious errors appear in the best in electronics. Write for second paragraph, left column, on page 80. Free 1972 Catalog today The high -frequency resonance noted was SEND FOR IT TODAY! in the vicinity of 15,000 Hz (not 1500 r FREE TRIGGER Electronics, Dept. PE -2 Catalog 11z); channel separation reduced to be- 7361 North Ave., River Forest, III. 60305 tween 2 and 8 d13 above 12,000 Hz (not Send FREE 1972 TRIGGER Catalog 1200 Hz). Our sincerest apologies for our Naar goof. PRINT

"VHF Frequency Converter," Decem- Address ber, 1971. The IC used should be CA3018 not CA3023. The \16970 can be substituted. City State Zip CIRCLE NO. 46 ON READER SERVICE CARD FEBRUARY 1972 89 Announcing the CIE ELECTRONICS LABO ` AUORY

Light-years ahead of any other way to learnelectronics.'-_

so -

11. -FY _ B y

90 POPULAR ELECTRONICS Including -World Electionirs Electronic "kits" are out! Now you can have your own electronics laboratory.

You'll perform hundreds of exciting experiments like these with authentic electronic components used by industry.

1i H ' uY,

MU. -. , - integrated on a Working with basic single transistor Observing transistor operating as shunt - Assembling circuit iden- circuit-Student learns best installa- fed amplifier - Student has installed an printed circuit board-Circuit is used in latest IBM System tion and troubleshooting techniques. He oscillator and shunt -fed amplifier. He tical to one 360 computers. Student is constructing has constructed a basic single transistor takes various measurements and ob- a Darlington circuit, first step toward understanding serves the transistor operating as an am- an oscillator combined with more complex solid-state circuitry. plifier. This is a typical solid -slate circuit. pair output amplifier. Prepare now for a high income career in the fast growing field of electronics. Rock- Electronic miracles are changing to- We are so certain that our Labora - Electric, IBM, North American day's world with breathtaking speed. tory Course will successfully prepare well, Raytheon and Westinghouse. you And with this electronics explosion you for a First Class FCC License Once you're enrolled with CIE listing of many has come a brand new need ... a examination, with Radar Endorse - will get a bi-nonthly open in for thousands of electronic ment, that if you fail the exam we will high -paying, interesting jobs demand testing, technicians, trained in theory and refund all tuition payments. designing, manufacturing, practice to build the products, oper- You get your FCC License, or you operating and repairing. be creat- ate them and service them. get your money back! More and more jobs will Don't wait for something to ed in the next few years. Start today You'll have high -paying new "happen" in your present job. Start to get ready for an exciting, job opportunities industry working right now to get ready for career in electronics ... the Electronics is in its infancy. Every- a career you'll really enjoy ... at of tomorrow. you turn you find new prod- $10,000... $12,000 or more a year. where ucts and equipment using space-age Don't put it off. Send now Experience with experiments circuitry. Computers. Improved for 2 FREE BOOKS is your best teacher radar for air traffic control. Mobile Mail the postpaid reply card for our Step-by-step learning cannot com- microwave communications. These School Catalog plus a special book pare with learning -by -doing. Now and many more examples of elec- on how to get your FCC License. If you can learn "why" as well as tronic technology have created thou- card is missing, use the coupon be- "how." You'll find out for yourself sands of new jobs - in companies low, of write to: Cleveland Institute the right way as well as the wrong like American Airlines, American of Electronics, 1776 East 17th Street, way to use electronic components, Telephone and Telegraph, General Cleveland, Ohio 44114. Butdo it now! to construct your own circuits, to discover trouble spots and learn r 1 how to fix them. CI CCleveland Institute of Electronics This new CIE course, Electronics G 1776 East 17th St-eat. Cleveland. Ohio 44114 Technology with Laboratory, teaches Please send me without cost or obligation: you electronics by making it work Approved 1. Your 44-page book, -How to Succeed in Electrorics." 2. Your book, -How to Get a Commercial FCC License."

before your eyes. And you do it your- under new I am especially inteested in: Electronics Technology with Laboratory self, with your own hands. G.I. Bill Electronics Technology O Industrial Electronics Electronic Communications First Class FCC License Importance of FCC License 'and Broadcast Engineering Electronics Engineering All CIE courses our money-back warranty are approved under the new G.I. An FCC License is a legal require- Name Age If jobs. And it Bill. you seemed (please print) ment for many important on active dety since January 31, is not easy to get! Address But more than 9 out of every 10 1955, or are In service now, check CIE graduates who take the Govern- box on card or City State Zip ment licensing exam pass it! coupon for G.I. Bill information. Check here for Cl.. Accredited Member National Home Study Council Bill information. A Leader to Electronics Training ... Since 1934 PE26 L CIRCLE NO. 9 ON READER SERVICE CARD FEBRUARY 1972 93 Television Scene

By Forest H. Belt

a rash of advertising, there are DESPITEstill people who don't know what a Trinitron is. A few think it's some kind of TV set. Others know it's something special from Sony, but they're not sure what. The Trinitron is a picture tube for color television. Sony introduced the first color receiver using a Trinitron several years ago, a 7 -inch model that never got into production. But more recently, both 9- and 12 -inch versions have been imported in quantity. And just this past winter, a 17 -inch model appeared in the U.S. The "large- screen" Trinitron resembles its predecessors, but incorporates definite changes. The Trinitron CRT is touted as being simpler than American color tubes. The advantage isn't all that obvious to a viewer; but inside the cabinet, the Trinitron operates \vith comparatively few circuits. For example: Any color set has critical adjustments to register the primary red, blue, and green rasters accurately on top of each other. The term is convergence, and Fig. 1. Standard triad dot pattern the object is to keep colors from fringing (top) and Trinitron stripe pattern. black -and -white pictures. An ordinary color set, American or Japanese, has seventeen differs from the usual picture tube in convergence adjustments. A receiver using several important ways: (1) The Trinitron the Trinitron has only a half -dozen or so. phosphor screen is deposited in narrow Credit for simplification goes to the way vertical stripes instead of tiny dots. (2) The the Trinitron picture tube is structured. It mask behind the Trinitron phosphor is a grille of vertical slots instead of a shadow mask of round holes. (3) The Trinitron emits three beams, one for each primary color, but from only one electron gun; the Trinitron- ordinary color CRT has three separate guns. (4) The beams in a Trinitron are side -by -side whereas in a conventional color tube they are spaced in a triangular Still A relationship. (5) Special plates converge Trinitron beams electrostatically; a conventional color CRT converges electromagnetically, with a yoke of coils Mystery around the neck of the tube. (The newer

9d POPULAR ELECTRONICS Including Electronics World a PHOSPHOR large -screen Trinitron uses convergence DOT SCREEN yoke, controlled by only three adjustments.) PERFORATED Stripes Instead of Dots. First, consider SCREEN MASK the phosphor. Compare the two photos in Fig. 1. The dots arranged triangularly belong to the phosphor of a conventional color tube. Each triad of dots contains one RED GUN ELECTRON red clot, one green, and one blue. BEAMS The stripes in the other photo are a GREEN Trinitron phosphor. Each stripe is one color. GUN A They line up red, green, blue, red, green, BLUE blue, and so on. GUN Either kind of phosphor needs some sort electron beams of mask between it and the source of the beams. Otherwise, any electron beam could phosphor "splatter" onto adjacent dots or stripes, stripes thus activating the wrong color. In the aperture conventional picture tube, a perforated grille metal screen (Fig. 2A) confines the size of each beam. Because the metal sheet "shades" the edges of the beams, the name shadowmask has become accepted. The Trinitron electron beams get similar treatment. The masking metal screen (Fig. 2B) contains vertical slots rather than round holes. Sony calls the mask an B aperture grille. The phosphor stripes are very narrow compared to the beams. Each beam spreads across two slots in the grille. Fig. 2. At top is shadowmask scheme; But the angle at which each beam strikes the below, Trinitron CRT aperture grille. grille slot nevertheless directs it to the correct phosphor stripes. through straight, strikes the slotted How this works is illustrated in Figs. 3 masking grille exactly perpendicular. The and 4. Back in the Trinitron electron gun, wide beam spreads over two of the aperture the red and blue beams bend, cross, and slots-and then some-but the metallic aim outward, while the green beam grille blocks all except what can get through remains straight. As they pass between the those two slots. The aperture grille convergence plates, the'red and blue beams positioning lets the green beam straight are directed hack toward the ce inter axis. If through to illuminate two green phosphor convergence is correct, all three beams stripes. cross again precisely at the aperture grille. The red beam, having been bent lou can see the effect on individual outward and then back inward, strikes the beams in Fig. 4. The green beam, coming aperture grille from an angle. The slots-

Fig. 3. The gun in a Trinitron emits and controls all three color beams; in ordinary color -TV picture tube, three separate guns are used to make beams.

GI G2 convergence focus plates

1 1

B J1 r) i - B cathodes G -1 G R

FEBRUARY 1972 95 the same ones that let two green beam - segments through-pass only enough red beam to illuminate two red stripes of phosphor. The angle of the red beam just ELECTRON REAM suits the positioning of the red stripes with ( 'twin ). respect to the grille openings, and the red aperture beam does not touch green or blue stripes. 5 /grille The blue beam approaches from the =2:1c:31 angle opposite the red. The slotted aperture passes hvo beams just wide phosphor enough, and at the correct angle, to hit only blue phosphor stripes. pi I R B rG RG l B R G< Of course, all the while, the three beams are being swept from side to side and from top to bottom to form a raster. As you view the front of the Trinitron picture tube, the picture looks about like it does on any ELECTRON BEAM regular color CRT-unless you inspect it <(red) closely. Then you can see the individual lighted vertical stripes, just as you can see individual phosphor dots on the screen of a t..t:. conventional color tube if you look closely. s

Three From One. The sketch in Fig. 3 shows the gun structure of a Trinitron. Conventional color picture tubes have three separate electron guns, each with its 1G B R G B R G B own heater, cathode, grid 1, grid 2, and focus anode. The three heaters share common base connections, and all three focus anodes go to one base pill. But the ELECTROW BEAM other elements in all three guns have their ( btuá ) separate base connections. In early Trinitrons-the 9- and 12-inch- only the cathodes are separate. Grid 1 is common to all three cathodes, and thus t.y+:

96 POPULAR ELECTRONICS Including Electronics World curvature of the phosphor screen and ABOUT YOUR aperture grille. Compared to a typical color tube, the SUBSCRIPTION Trinitron converges with extreme simplicity. Your subscription t0 POPULAR ELECTRONICS iS is striped instead of Because the phosphor maintained on one of the world's most modern, dotted, slight vertical misconvergence efficient computer systems, and if you're like 99% hardly matters. So, adjustments are reduced of our subscribers, you'll never have any reason to a bare minimum. Once mechanical to complain about your subscription service. when do arise, is adjusted with four We have found that complaints (static) convergence the majority of them occur because people have neck magnets, a mere two controls shape written their names or addresses differently at the parabolic signal for dynamic different times. Far example, if your subscription convergence. It takes four magnets plus were listed under "William Jones, Cedar Lane, thirteen controls to converge other color Middletown, Arizona," and you were to renew it as "Bill Jones, Cedar Lane, Middletown, Arizona," tubes. our computer would think that two separate sub A new 17 -inch Trinitron gives up some scriptions were involved, and it would start send- of the simplicity of small -screen models. ing you two copies of POPULAR ELECTRONICS each month. Other examples of combinations of names For one thing, ill., electron gum is more that would confuse the computer would include: complicated. Each cathode has a control John Henry Smith and Henry Smith; and Mrs. grid (Cl) of its own. That necessitates extra Joseph Jones and Mary Jones. Minor differences in circuits, and alterations in the way video addresses can also lead to difficulties. For exam- and color signals are fed to the Trinitron. ple, to the computer, 100 Second St. is not the same as 100 2nd St. Otherwise, the gun in the larger Trinitron So, please, when you write us about your sub- hasn't been changed much. scription, be sure to enclose the mailing label Scanning the wider screen also brought from the cover of the magazine-or else copy your problems that necessitate more elaborate name and address exactly as they appear on the mailing label. This will greatly reduce any chance convergence. The plates inside the tube of error, and we will be able to service your still get high de for basic convergence, but request much more quickly. no parabolic signal. Instead the I7 -inch Trinitron has a small yoke of convergence coils around the picture tube neck. Even so, FREE! RADIO SHACK adjustments are much simpler than for Accessories & Parts Catalog conventional picture tubes. A mere half - dozen controls sloes the entire job. NEW 1972 Edition! Whither Color CRT's? The Trinitron is THE buying guide for kit the first drastic change in picture -tube builders. CB'ers. installers, technology since color television came on experimenters. fix -it men, hobbyists, electricians - the market. It represents a major step anyone in electronics in 1"" 119 Pu + toward making color receivers easier to any way! adjust and repair. Trinitron chassis Electronics A to Z-Antennas, represent the start of a design t end to Batteries, Capacitors, Diodes, minimize critical stages, which in the long Educational Kits. Fiber Optics. ?", run eliminates nuisance maladjustment. Grille Cloth, Hi -Fi Speakers, IC's, Jacks, Knobs" Other sections of both color and L -Pads, Mikes, Needles, Oscillators, P -Boxes. monochrome receivers could benefit from Quadracs, Resistors. Semiconductors, Telephones, similar Ultrasonic Alarms, VHF Antennas, Wire, Xenon attention. Strobe, "Y" Adapters, Zener Diodes plus our \leanwhile, what else can be clone for Science Fair and Knight -Kit electronic kits! picture tubes? The most sought-after r innovation is a fiat with little Dept. PE -181 screen, 2725 W 7th St. thickness. The Trinitron design boasts short Fort Worth. Texas 76107 neck length as well as small neck diameter. Send me your FREE 1972 Catalog 9215 Butt the front -to -back dimension of Please PRINT Clearly Trinitron receivers subtracts little from Name Apt 9 other designs. Whoever comes up with a picture tube under 6 inches from screen to Street or Rte. & Box socket will have taken a giant step toward City the ideal of a hang -on -the -wall color State Zip _J picture tube. OO CIRCLE NO. 3 ON READER SERVICE CARD

FEBRUARY 1972 97 GC ELECTRONICS Rockford. 111. 61101 C CALECTRO sonE:º ak 1.11. ~Mi+., .1 r._s.t_ aB d""»átd ..n4Trt{1bI,IR1er«Es+ ._ are ontfQaaar .oee ' y t° 1 -ft{ ""», "11'."1'4'11 P ? reP-a ` Ilit sG 1191..b-1: kiesax.l.1 _-a' '' ' 111:1:11 n,bn ^t II11 ?,."('r,Isr" [^ t:po:Tlll cejaarirac:; Ip . ,.: 11iwiw LHfig; l e D.;a. 7'5313i17: ;o. add; t°a + rwti!xd a1111F--t

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CALECTRO ELECTRONIC ACCESSORIES include:

Everything for the hobbyist and electronics enthusiast. There's even a handbook showing hundreds of Calectro items, plus tips, hints and "do-it-yourself' projects. See the Calectro line-up at any of these Calectro distributors:

ALABAMA Glendale: Logan's Glendale Venice: Sun Electronics Electronics Albertville: Elect. Parts & Supply Co. Goleta: Dow -Radio -Milo Ventura: Lombard's Alexander City: Cherokee Elect. Supply Hayward: L Inc. Walnut Creek: E. C. Wenger Mission Anniston: Lafayette Radio Inglewood: Inglewood Electronics West Covina: Electronics Points Elect. Inglewood: Sterling Home Elect. Westminster: J. K. Electronics Birmingham: Five Electronics Birmingham: Lafayette Radio La Habra: A. B. C. Electronics Westwood Village: Sterling Birmingham: Mitchell Electronics La Mesa: Heathkit Electronics Whittier: Oxbow Electronics Electronics Selectronic Supply Co. Electronic Dist. Ltd. Whittier: Whittier Birmingham: Lancaster: Woodland Hills: Heatnklt Elect. Center Dothan: Azar's Elect. Supply Lawndale: Electronic Dist. Hills: Woodland Electronics Gadsden: Southeastern Radio Parts Los Altos: Alco Paramount Woodland Yucca Valley: Mission Electronics Huntsville: Electronic Center Los Angeles: American Elect. Supply Mobile: Elect. World Inc. Los Angeles: Calif. Electronics Supply COLORADO Mobile: Grice Electronics Los Angeles: Federated Electronics Arvada: Team Electronics #51 Montgomery: Handey's Elect. Center Los Angeles: Heathkit Electronics Aurora: Alphatronics Lafayette Parts Montgomery: Southeastern Radio Monterey: Zac-Kit Corp. Boulder: Lafayette Elect. Parts Radio Selma: Roes Electronic Mountain View: Lafayette Boulder: Rocky Mtn. Elect. Supply Radio Tuscaloosa: Radio Parts, Inc. National City: Lafayette Boulder: Team Electronics #59 Lewis Electronics N. Hollywood: :Colorado Springs: D & M Electronic ALASKA Norwalk: Elliott Electronics Anchorage: Elect. Corp. of Alaska Supply Oakland: Brill Electronics Colorado Springs: Romar Inc. Anchorage: Team Elect. #31 Ontario: Lafayette Elect. Polar Electronics Denver: Denver Walker Elect. Fairbanks: Orange: Vans Electronics Juneau: Alaska Radio Supply Denver: Heathkit Elect. Center Oxnard: Advance Electronics Denver: Lafayette Assoc. ARIZONA Oxnard: Dow Radio -Milo Denver: Team Electronics #67 Flagstaff: Jean & Trox, House of Sound Pacoima: Panorama Electronics Denver: Team Electronics #73 Mesa: Hi -Fi Sales Palo Alto: U. S. Electronics Durango: L. B. Walker Radio Phoenix: Dalis Radio & TV Supply Palo Alto: Zack Electronics Ft. Collins: Pioneer Elect. Inc. Phoenix: Electronic Dist. Paradise: Reed Electronics Ft. Collins: Sound Shack Inc. Phoenix: Heathkit Elect. Ctr. #2B Pasadena: Dow Radio -Milo Ft. Collins: Team Electronics #56 Co. Phoenix: J & S Electronics Pomona: R. V. Weatherford Greeley: Greeley-Walker Elect. Phoenix: Sterling Electronics Porterville: Western Assoc. Stores Pueblo: Pueblo Radio TV Supply Sierra Vista: Trade Mart Sound Dept. Redondo Beach: Sterling Home Tucson: South, Arizona Wholesale Elec. Electronics CONNECTICUT Yuma: Yuma Radio & TV Supply Redwood City: Heathkit Elect. Center Bridgeport: Hairy of Bridgeport Ridgecrest: Miller Elect. Supply Danbury: Danbury Hi Fi T. V. ARKANSAS Riverside: Mission Electronics Danbury: Sound Service Arkadelphia: Mid State Supply (2 locations) Groton: Frances Blytheville: Bluff City Distributors Sacramento: Dunlap Electronics Groton: Lafayette Radio Crossett: Launius TV -Electric Sacramento: Lafayette Radio Hartford: Hatry of Hartford El Dorado: Industrial Elect. Supply Sacramento: Lombards Electronics Hartford: Scell Elect. Inc. Ft. Smith: Carlton Bates Co. Sacramento: Norcal Electronic Inc. Kensington: Modern Electronics Ft. Smith: Carter Electronics Sacramento: Zac-Kit Corp. New Britain: United Electronics Supply Hot Springs: Prince Electronics San Bernardino: Mission Electronics New Haven: Hatry Electronics Hot Springs: David White Elect. San Diego: Dow Sound City Old Saybrook: Zack Supply Jonesboro: Bluff City Dist. Co. San Diego: Lafayette Radio Elect. Stamford: Atlantic Electronics Little Rock: Lafayette Radio Assoc. San Diego: Western Radio & TV Supply Torrington: TV Lab. & Comm. Magnolia: Elect. Supply Inc. San a rancisco: Hauer tiectronic Supply Waterbury: Hatry of. Waterbury N. Little Rock: Carl's Electronics San Francisco: L Inc. Pine Bluff: Lafayette Radio Elect. San Francisco: San Francisco Radio DELAWARE Dover: Lafayette Radio Elect. Pine Bluff: David White Electronics San Francisco: Zack's Electronics Wilmington: First State Elect. San Gabriel: Valley Radio Center CALIFORNIA. San Jose: Alco Paramount Elect. Corp, (2 locations) Anaheim: Heathkit Elect. Center Radio Electric Service San Jose: Peninsula Electr. Supply Wilmington: Anaheim: Henry Radio San Jose: Cluement Electronics Anaheim: Orvac Electronics DISTRICT OF COLUMBIA San Luis Obispo: Mid -State Elect. -Fi Anaheim: United Sound & TV Co. Washington, D.C.: German Hi Supply Bakersfield: Cletes Electronics Supply Washington, D.C.: Silberne Ind. Sales Santa Barbara: Lectronic Kits & Parts Bakersfield: Lafayette Radio Elect. Santa Barbara: Lombards Electronics FLORIDA Bellflower: Giant Electronic Supply Santa Cruz: Santa Cruz Electronics Cocoa Beach: Sunset Electronics Roper Electronics Bellflower: Santa Maria: Lombards Electronics Clearwater: Stereo City Berkeley: Al Lasher's Electronics Santa Monica: Apollo Electronics Daytona Beach: Electro -Supply Co. Berkeley: Cal Hi -Fi Santa Rosa: Fred Plante Electronic Inc. Daytona Beach: Lafayette Assoc. Lafayette Radio Berkeley: Simi: Glens Electronics Eau Gallie: Florida Elect. Supply Corp. Berkeley: Zac-Kit Simi Valley: Village Electronics Fern Park: 21st Century Elect. Buena Park: S.J. Radio Electronics S. Lake Tahoe: Alpine TV & Supply Ft. Meyers: Lafayette Radio Burbank: Electronic City City: 2002 The Sound Odyssey Ft. Walton Beach: Grice Elect. Electronics Studio Burbank: Varsity Sunnyvale: Sunnyvale Electronics Gainesville: Public Radio Shop Camarillo: Camarillo Electronics Tarzana: 2002 The Sound Odyssey Hialeah: Heathkit Elect. Center Campbell: Alco Paramount Temple City: G & M Wholesale Elect. Hollywood: 21st Century Elect. Canoga Park: Sandy's Electronics Thousand Oaks: Sandy's Electronics Jacksonville: Fowkes Electronic Costa Mesa: Marvac Electronics (2 locations) Mart Supply Culver City: Electro Torrance: Cash Electronics Miami: Electro -Standards Lab Trading Post Culver City: Elect. Torrance: L. A. Elec. Radio Sales Miami: Mountain Electronics t. Los Angeles: mark Papel Stereo Last Torrance: Signal Electronics Miami: 21st Century Elect. Dow Sound El Cajon: City Torrance: Home Electronics Miami: Walder Electronic Dist. Center Sterling tl Cerrito: Heatnklt Electronic Tujunga: Electra Mart N. Miami: Davis Communications B. Supply Fontana: C. Radio Tustin: A. B. & B. Electronics Orlando: Olson Electronics Fresno: Dunlap Electronics Upland: Mission Electronics Orlando: 21st Century Elect. Fresno: Electronic Eng. Dist. Vallejo: Zac-Kit Corp. Panama City: Audio Sound Co. Electronics Fresno: Sparky's Van Nuys: Lafayette Electronics Panama City: Lafayette Assoc. Store Glendale: Eagle Electronics

98 POPULAR ELECTRONICS Includin7 Electronics World GC ELECTRONICS Rockford, III. 61101 C CALECTRO

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Pensacola: Electronic Supply Greenwood: Electronic Center Greenfield: Sdylee Elect. Supply Pensacola: Grice Electronics Indianapolis: Electronic Dist. Inc.. Hyannis: Lafayette Radio Pensacola: Gulf Radio & TV Indianapolis: Graham Elect. Supply Hyannis: Lafayette Radio Elect. St. Petersburg: Xetex Electronics (2 locations) Lawrence: Malco Elect. Inc. Tallahassee: Lafayette Radio Indianapolis: RaDisCo., Inc. Lexington: Wholesale Elect. Supply West Palm Beach: Lafayette Radio Kokomo: Thatcher & Assoc. Medford: Medford Music 'Lafayette: C. W. Y. Elect. N. Adams: Elect. Supply Center GEORGIA Lafayette: Lafayette Radio Supply N. Dartmouth: Lafayette Radio Alban Rodd Elect. Michigan City: Lafayette Electronics 'N. Dartmouth: Radio Shack Assoc. Albany: Southeastern Radio Pts. Muncie: Muncie Elect: Supply Northampton: C & I Dist. Inc. Athens: Southeastern Radio Pts. Muncie: Standard Radio Parts Peabody: Cramer Electronics Atlanta: Heathkit Elect. Center Rensselaer: Midway Elect. Peabody: Tee-Vee Supply Co. Atlanta: Chas. S. Martin Dist. South Bend: Radio Dist. Co. Pittsfield: Pittsfield Radio Co. Atlanta: Southeastern Radio Pts. Terre Haute: C. T. Evinger Co. Pittsfield: Seiden SoundLafayette Augusta: Dixie Radio Supply Co. Valparaiso; Jess Bowman & Assoc. Raynham: David Dean Elect. Brunswick: M & M Elect, Springfield: Del Padre Elect. Dist. Columbus: Lafayette Radio & Elect. IOWA Wellesley: Cramer HiFi Macon: Clark Elect. Dist. Co. Ames: Electronic Supply Wellesley: Heathkit Electronics Electronics Macon: Southeastern Radio Pts. Cedar Rapids: Team #21 West Newton: A. W. Mayer Co. Savannah: Electronic 21 Davenport: Union Supply Co. Worcester: Wholesale Electronics Assoc. Savannah: Lafayette Assoc. Des Moines: Lafayette Worcester: Worcester Radio Dist. Savannah: Parts Unlimited Des Moines: Team Electronics #12 Savannah: Southeastern Radio Pts. Dubuque: Team Electronics #7 MICHIGAN Electronics Ft. Dodge: Team #16 Ann Arbor: PentICHIG Inc. Elect. Inc. HAWAII Iowa City: Hagen Ann Arbor: RadioTronics Team Electronics Hilo: Radio TV Corp. Mason City: #10 Bay City: Bay TV Lafayette Co. Honolulu: Electrical Equip. Co. Sioux City: Molstad Dist. Bay City: Radio-Tronics Team Honolulu: Lafayette Assoc. Sioux City: Electronics Benton Harbor: Collar Distributing Honolulu: Precision Radio Ltd. Waterloo: Team Electronics #20 Birmingham: Nutrrtnics Inc. IDAHO KANSAS Dearborn: West Side Radio Barton Electronics Boise: Kimball Electr. Coffeyville: Norman Electronics Detroit: Coomes Dist. Biose: Service Electronics Co. Garden City: Team Electronics #46 Detroit: Caldwell: A.Gem Supply Hutchinson: Lett Elect. Inc. Detroit: Electronic Parts Co. Heathkit Elect. Center Lewiston: Columbia Electric Hutchinson: Team Electronics #54 Detroit: United Electronics Detroit: Radio Elect. Supply Co. Twin Falls; Manhattan: Acme Elect. Center Mission: Heathkit Electronic Center E. Detroit: Heathk& Team Electronics #74 ILLINOIS Santa Fe Electronics Escanaba: Electronics Olathe: Inc. Belleville: Lurtz Topeka: Seabrook Radio & TV Flint: Shand Electronics Berwyn: B. B. & W. Inc. Topeka: Team Electronics #64 Grand Rapids: Radix Parts Inc. Bloomington: Team Elect. #72 Amateur Radio Equipment Grand Rapids: Radix-Tronics Assoc. Wichita: Carbondale: Lafayette Cliffs Wholesale Elect. Iron Mountain: J &1R Electronics Elect. Supply Wichita: Carbondale: Suedekum Wichita: Lafayette Radio Jackson: Fulton Radio Supply Team Electronics #43 Carpentersville: Team Electronics #48 Kalamazoo: Electronic Supply Corp. Radio Doctors Wichita: Champaign: Wichita: Team Electronics #53 Kalamazoo: Kaltronics Inc. Chicago: Gemco Kalamazoo: RadioTronlcs Chicago: Heathkit Elect. Center KENTUCKY Kalamazoo: Warren Radio Chicago: Joseph Electronics Covington: Holub Dist. Co. Lansing: Fulton Radio Chicago: K & M Audio Inc. Laconia: Holub Lafayette Livonia: Northwest Elect. Chicago: Olson Elect. Western Lexington: Tel-Rad-Elect. Ind. Livonia: Robbie Electronics Chicago Heights: Heights Electronics Paducah: Paducah Elect. Supply Menominee: Team Electronics #29 Downers Grove: Heathkit Electronic Paducah: Warren Radio Midland: Radio Pares Co. Center LOUISIANA Muskegon: Elect. Dist. E. Moline: Team Electronics #61 Muskegon: Western Elect. Supply Alexandria: House of Elect. Evanston: Tri-State Electronics Niles Radio Supply Baton gouge: Davis Elect. Supply Niles: Evergreen Park: Playback, inc. Port Huron: Main T. V. Supply Glendale Heights: Allied Radio Shack Baton Rouge: Sterling Elect. Gretna: Sterling Elect. Royal Oak: Reno Radio Joliet: Mainline Supply Parts & Service Metairie: Pelican Elect. Supply Saginaw: Philso Kankekee: Mainline Supply St. Joseph: Heathkil Electronics Monroe: C & 0 Elect. Lombard: Stier Industries Southgate Center: Radio-Tronics New Orleans: Columbia Radio Supply Lombard: Team Electronics #70 Hgts.: L.R.E. Electronics New Orleans: Shuler Supply Co. Sterling Moline: Lofgren Distributors Traverse City: Dynatronics Inc. Niles: Joseph Electronics Shreveport: Industrial Elect. Supply Assoc. Warren: J K Electronics Oak Lawn: Eland Electronics Sulphur: Lafayette Ypsilanti: RadioTronics Peoria: Warren Radio Co. W. Monroe: Brooks Supply Rantoul: Music Box MAINE MINNESOTA Trigger Electronics Schack Electronics River Forest: Bangor: Consumer Electronics Brooklyn Center: H Elect. Radio Rockford: H & Rockland: Amateur Equipment Co. Duluth: Northwest Rockford: J & M Electronics Lafayette Assoc. Duluth: Team Electronics #41 Elect, South Portland: Rockford: Lafayette Waterville: Lafayette Assoc. Edina: Schaak Electronics Rockford: Team Electronics #69 Hibbin: Allied Elect Corp. Rock Island: Team Electronics #22 MARYLAND Hibbing:ns: Team Electronics 24 Springfield: Team Electronics #71 Aberdeen: Harco Electronics Heathkitm Electronics Center Urbana: Lafayette ElectronicsHopkins:Baltimore: AmateuricaRadio Mankato:cap: Team Electronics #23 Waukegan: Badger Elect. Baltimore: American Dist. n AllieddcRadioRadio Corp. Waukegan: Chester Electronics Baltimore: Henry 0. Berman Co.Minneapolis:C Minneapolis: Electronics Center Inc, Empire Electronics Supply Minneapolis: Schaak Electronics INDIANA Bethesda: Lexington Park: Bill Raleys Sales (2 locations) Anderson: Elect. Supply Center Minneapolis: Team Central Supply Anderson: Seyberts Radio City: Lafayette Radio Minneapolis: Team Electronics #1 Bloomington: Stansifer Radio Ocean Rockville: Capitol Radio Wholesalers Minneapolis: Team Electronics #5 Lafayette Assoc. Crawfordsville: Rockville: German Hi Fi Centers Team Electronics #13 East Chicago: Acro Dist. Co. Minneapolis: Rockville: Heathkit Elect. Center Moornead: learn tlectronlcs #14 Elkhart: Warren Radio Lafayette Radio Elect. Schaak Electronics Evansville: Hutch & Son Elect. Salisbury: Rochester: Towson: Baynesville Elect. Rochester: Team Elemronics #3 Valley Sound Evansville: Ohio Electronic Dist. Inc. Electronics Wayne: Ft. Wayne Elect. Supply Wheaton: Roseville: Schaak Ft. Team Electronics #4 Ft. Wayne: Harvey's St. Cloud: MASSACHUSETTS St. Paul: Allied Radio Corp. Ft. Wayne: Lafayette Assoc. Lafayette Radio Associate Billerica: St. Paul: Schaak Electronics Ft. Wayne: Pembleton Elect. Elect. Supply Boston: O'Donnell St. Paul: Team Electronics #2 Ft. Wayne: Warren Radio Boston: Yankee Electronics CIRCLE NO. 21 ON READER SERVICE CARD

FEBRUARY 1972 99 GC ELECTRONICS C CALECTRO Rockfo,rl, Ill. 61101 snowman.. s -11i! urax.+a..w w m1á16: :Lill a ( GC 1101

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Paul: Team Rockaway: St. Electronics #44 Lafayette Radio & Elect, Asheville: Freck Radio & Supply Paul: Team Springfield: St. Electronics #66 Federated Purchaser Charlotte: Dixie Radio W. St. Paul: Team Springfield: Route Electronics #58 Elect. Inc. Charlotte: United Electronic Supply Willmar: Team Electronics Trenton: Dist. Co. #25 Jackson Concord: Mac Victor Elect. Supply Trenton: Nidisco Inc. MISSISSIPPI Durham: Vickers Elect. Supply Union City: Nidisco Co. Columbus: Bluff City Dist. Co. Gastonia: Skillet Dixon Inc. Wanamassa: Reyal Electronics Greenville: Bluff City Dist. Co. Greensboro: Lafayette Assoc. Greenville: Electronic Workshop NEW MEXICO Greenville: Pair Electronics Inc. Hickory: Freck Greenwood: Parham Electronics Albuquerque: Electronics Parts Co. Radio & Supply Hattiesburg: Gillilands Teague Elect, Albuquerque: 4Tronics New Bern: Lafayette Radio Elect. Raleigh: Lafayette Jackson: Lafayette Assoc. Albuquerque: Sterling Electronics Electronics Jackson: Swan Electronics Inc. Clovis: Electronic Parts Shelby: Freck Radio Meridian: Hooper Elect. Supply Farmington: Lektronix Supply Statesville: Electronic Center Pascagoula: May Elect. Dist. Co. Las Cruces: Mannie's Statesville: Mac Victor Elect. Supply Elec. Supply Winston-Salem: Tupelo: Bluff City Dist. Co. Santa Fe: Sepco Inc. Lafayette Radio Tupelo: Mid Southern Electronics Winston-Salem: 21st Century Elect. NEW YORK NORTH MISSOURI Albany: Lafayette Radio DAKOTA Cape Girardeau: Suedekum Elect. (3 locations) Bismarck: Team Electronics #30 Grand Team Supply Albany: Seiden Sound Forks: Electronics #26 Columbia: Missouri Cable Co. Amherst: Heathkit Electronic Ctr. Mandan: John Iverson Co. Minot: John Grandview: Truman Corner RCA Sales Bayside: Jean Electronics Iverson Co. Minot: Team Electronics Joplin: Four -State Electronics Bellerose: S & R Electronics #32 Kansas City: Manhattan Radio & Bethpage: S & R Electronics OHIO Equip. Co. Binghamton: Morris Electronics Akron: Fox Radio Parts Kansas City: Radiolab Co. Bronx: Bay Elect. Dist. Ashtabula: Morrisons Electronics Kansas City: Team Electronics #50 Bronx: Post Tronics Corp. Cincinnati: Holub City: Lafayette Store Kansas Team Electronics #63 Brooklyn: Brooklyn Electronics Cincinnati: Newark-Herrlinger Poplar Bluff: Tri-State Elect. Buffalo: Dymac Inc. Cincinnati: United Radio Audio Ctr. St. Joseph: Acme Radio Buffalo: Purchase Radio Elect. ..(2 locations) St. Louis: Heathkit Electronics (3 locations) Cleveland: Communications World Louis: Sickle Co. St. Van Radio Buffalo: Radio Equipment Corp. Cleveland: Fox Elect. Radio Parts Sikeston: Baileys Supply (3 locations) Cleveland: Heathkit Electronics Springfield: Assoc. Lafayette Commack: S & R Electronics Cleveland: Warren Radio Springfield: Norman Electronics Co. Corning: Chemung Electronics Defiance: Dick DeWolfe Elect. Springfield: Team Electronics #57 Dunkirk: Barker -Higbee E. Liverpool: Television Parts Co. MONTANA Elmira: Chemung Electronics Lancaster: Lafayette Radio Elmira: JPB Specialty Co. Billings: Teama Electronics #33#4 Electronics Bozeman: Farmingdale: Harrison Radio Corp. Lima: Hutch & Son leElctronicss Flushing: Great Falls:T Lafayette Assoc. Allen Electronics Mansfield: Fox Radio Parts Greatt:Falls: TeamaElectronics #3S Flushing: Jean Electronics Mansfield: J. R. Electronics Glenn Falls: Seiden HavHavre: Northern ElElectrons Sound Mansfield: Servex Eelctra Dist. Hempstead: Davis Electronics Corp. Marion: : Electronicl Parts Semen Electra Dist. Missoula: Northwest Dist. Herkimer: Herkimer Electronics Minster: Gudorf & Moorman Missoula: Team Electronics #37 Hicksville: Electronics City Sandusky: Servex Electra Dist. Ithaca: Lafayette Assoc. Sebring: Collins Dairy Store NEBRASKA Jamaica: Harrison Radio Corp. Springboro: Franklin Electronics. Gering: Corr & Johns Radio TV Jamaica: Jean Electronics Toledo: Fox Radio Parts Lincoln: Team Electronics #27 Jamestown: Warren Radio Warren: REM Elect. Supply Omaha: Omaha Electric Kingston: Lafayette Radio Washington Court House: Hutch & Omaha: Team Electronics #28 Lake Grove: Towne Camera & Elect, Son Omaha: Team Electronics #34 Lindenhurst: Barstan Electronics Woodlawn: Heathkit Elect. Center Omaha: Team Electronics #47 Merrick: Electronics Unlimited Wooster: Servex Electra Dist. Scottsbluff: D & H Electronics Newburgh: Action Audio Inc. Youngstown: Armies Electronics Scottsbluff: Joachim Radio Supply New Hyde Park: Electronic City Youngstown: Clark Electronics Zanesville: Thompson Radio NEVADA New Paltz: Vista Camera Supply New York: Adson Radio & Elec. Las Vegas: Lafayette Radio Elec. OKLAHOMA New York: Consolidated Radio Las Vegas: Metcalf Electronics Bartlesville: Cummins Elect. New Vork: Harrison Supply Reno: Dunlap Electronics Radio Enid: Radio Shack New York: Heathkit Radio Reno: Lafayette Electronics Midwest City: Radio Supply New York: Hone Electronics Oklahoma City: Radio Supply Inc. NEW HAMPSHIRE New York: Midway Radio & TV Corp. Oklahoma City: Sterling Electronicse Concord: Evans Radio Inc. New York: Sylvan Wellington Co. Oklahoma City: ebng Home Elect, Niagara Falls: Market Radio & TV NEW Oklahoma City: Webb Electronic JERSEY Niagara Falls: Radio Equipment Bayonne: J & E Electronics Sales Inc. Olean: Radio Equipment Corp. Berlin: Midstate Radio Supply Stillwater: Hamilton Electronics Patchogue: T &. M Electronics Bloomfield: Tulsa: Lafayette Assoc. Berger Electronics Peekskill: Action Audio Supplies Tulsa: Team Electronics #77 Plattsburgh: G F Bricktown: & Elect. Parts Unlimited Plattsburgh: Lafayette Camden: Renco OREGON Poughkeepsie: Higgins & Sherr Eugene: Thompson's Lafayette Chatham: Music World Elect. Elect, Poughkeepsie: Lafayette Portland: Electronic Supermarket Cherry Hill: Dee's of N.J. Riverhead: D & S Electronics Portland: Electronic Cherry Hill: Renco Wholesale Mart Rochester: Heathkit Electronics Portland: H & R Denville: Lashes Electronics Inc. Radio Supply Rochester: Rochester Radio Supply Portland: Northwest Radio Englewood: Gorman Bros. Supply Rome: Rome Electronics Portland: Portland Radio Fair Lawn: Goodman Inc. SuPPIy -Shaw, Schenectady: Seiden Salem: Wasson's Fair Lawn: Sound Lafayette Heathkit Electronics Staten Island: Dist. Hackensack: Nidisco Inc. Electronic Corp. Tonawanda: Purchase Radio PENNSYLVANIA Hanover: State Electronic Pts. Troy: Trojan Electronics Allentown: Federated Purchasers JerseyCity: Nidisco Y Inc. alts: Altoona: Diamond Electronics Kearny: Kearny Electronics Wappingers Falls: Lafayettey Radio Ambridge: Television Parts Co. Newark: Parts Unlimited Westbury: Heathkit Elect. Center Bristol: Powell Electronic Sales Northfield: Rainbow Electronics Went Seneca: Purchase Radio Butler: Backer Electronics Paramus: Leonard Radio Woodbury: Harvey Co. Butler: Television Parts Co. Passaic: Nidisco Inc. Radio Woodside: Boro Elect. Inc, Chambersbur A Rahway: Ovad Parts Edwardsville: ArlaCns E#87ronicS Red Bank: Monmouth Radio Supply NORTH CAROLINA Erie: Mace Electronics Ridgefield: Nidisco Inc. Asheville: Bak.erElectronics, Inc, Erie: Warren Radio

100 POPULAR ELECTRONICS Including Electronics World GC ELECTRONICS C CALECTRO Rockford, III. 61101 terr 1. ...me. umE:.p Vwerrrum ro 17:::I .::::a i 7iEi1 nnt11R7P nnl il:oaq_am .r:: ,. r,,,.....lan.á.0 ....11lult.iliant :::nnenrnmaí: .... F rslil

Eynon: Symphony Inc. Corpus Christi: Lafayette Radio Virginia Beach: Lafayette Radio Greensburg: Lafayette Radio Corpus Christi: Sterling Electronics Elect. Johnstown: Lafayette Radio Dallas: Crabtree's Woodbridge: Lafayette Radio Kingston: Artco Electronics (4 locations) WASHINGTON Lancaster: Atomic Eeectra Co. Dallas: Heathkit Elect. Center McKeesport: Barno Radio Co. Dallas: Lafayette Radio Bellingham: Lafayette Radio Elect. Meadville: Warren Radio Dalias: Sterling Electronics Everett: Evergreen Electronics Monroeville: Heathkit Electronic Derfson: Denison Radio Supply Mt. Vernon: Skagit-Whatcom Elect. Center Demon: North Texas Elect. Seattle: ABC Communications American Mercantile New Brighton: Television Parts Co. El Paso: Frontera Electronics Seattle: Seattle: Citizens Band Service Oil City: R & S Elect. El Paso: Sunland Supply Co. Electronic Supply Co. Philadelphia: Herman Miller Co. Ft. Worth: Crabtree's Seattle: Pittsburgh: Cameradio Ft. Worth: Swieco Elect. Ctr. Seattle: Empire Electronics Pittsburgh: Heathkit Electronics Georgetown: Cap -Cam Dist Seattle: Heathkit Elect. Center Pittsburgh: House of Audio Houston: Heathkit Seattle: Pacific Elect. Sales Co. (2 locations) Houston: Mi -Tee Elect. Corp. Seattle: Pearl Radio & Elect. Co, Pittsburgh: Radio Parts Co. Irving: Crabtree's Seattle: Radio Supply Co. Pittsburgh: RPC Electronics Jacksonville: Lafayette Radio Seattle: Seattle Radio Supply Pittsburgh: Samson Dist. Co. Kileen: L & M Sales Co. Seattle: United Electric Pottstown: Harry Overholtzer Co. Laredo: Lafayette Assoc. Store Seattle: Western Elect. Supply Reading: George D. Barbey Co. Longview: Cole Electronics Seattle: Herb Zobrist Co. Scranton: Hart Electronics Longview: McLendon Radio Comm. Spokane: Alltronic Din. Sharon: Sharon Elect. Supply McAllen: McAllen Radio Supply Spokane: Don's Stereo Center State College: Alvo Electronics Midland: Lafayette Radio Spokane: Frank's Electronics State College: Cons. American Corp. Richardson: Martin Whsle Elect. Spokane: Northwest Elect. Trevose: Trevose Elect. San Angelo: F & 0 Electronics Spokane: Prudential Dist. Inc. Upper Darby: Resco Electronics San Antonio: Lafayette Radio Taconee: Wible Radio Supply Wilkes-Barre: Hart Electronics Corp. 12 locations) Yakima: Yakima White Electr, Willow Grove: Resco Electronics San Antonio: Sterling Electronics WEST VIRGINIA York: Sol Kessler's Hi -Fi Shop Texas City: Abcor-Lafayette Beckley: Halley Electronics Texas City: Electronic Supply Bluefield: Electronic Materials RHODE ISLAND Victoria: Wicks Radio Equip. Charleston: Electronic Materials Westerly: Lafayette Radio Waco: Waco Communications Clarksburg: Lafayette Radio Assoc. SOUTH CAROLINA UTAH Fairmont: Lafayette Radio Columbia: Dixie Radio Supply Logan: House of Sound Parkersburg: Stephenson T.V. Supply Columbia: Southeastern Radio Parts Manwill Electronic Supply Ogden: WISCONSIN Greenville: Dixie Radio Supply Salt Lake City: Kimball Electronics Appleton: Electronic Expeditors Greenville: Hemcor Inc. Salt Lake City: Manwill Supply Co. Greenville: Sawyer Elect. Corp. Appleton: Team Electronics #38 Salt Lake City: O'Laughlins Trudel"s Spartanburg: Dixie Radio Supply West Provo: Alpine Electronic Supply Appleton. Spartanburg: Hemcor Radio Supply Beloit: Lafayette Assoc. Cedarburg: Echo Communications Inc. SOUTH DAKOTA VERMONT Eau Claire: Team Electronics #6 Rapid City: Blackhills Elect. Supply Brattleboro: Lafayette Electronics Green Bay: Electronic Expeditors Rapid City: Chris Supply Burlington: Ind. Elect. Sales Green Bay: National Electronic World Rapid City: Team Electronics #40 Burlington: Lafayette Green Bay: Team Electronics #52 Sioux Falls: Team Electronics #11 VIRGINIA Janesville: Thomi:son Electronics Watertown: Team Electronics #19 Kenosha: Chester Alexandria: TV Workshop Electronics Supply TENNESSEE Annandale: Arcade Electronics LaCrosse: Team Electronics #17 Madison: Superior Radio Parts Athens: Reeves Electronics Arlington: Arlington Electronics Madison: Team Bristol: Lafayette Radio Elect. Blacksburg: Scotty's Radio TV Electronics #8 Madison: Team Electronics #62 Chattanooga: Curie Radio Supply Bluefield: The Three S Inc. Manitowoc: Team Electronics #39 Jackson: Bluff City Dist. Co. Centreville: Lafayette Radio Assoc. Milwaukee: Acme Radio Supply Johnson City: Freck Radio & Supply Charlottesville: Graves Elect. Inc. Milwaukee: Heathk it Electronics Johnson City: Lafayette Elect. Charlottesville: Wyse Electronics Milwaukee: Radio Parts Johnson City: L & S Electronics Colonial Heights: Lafayette Radio Milwaukee: Team Electronics Knoxville: Smith Electronics Supply Assoc. #15 Milwaukee: Team Electronics #68 Memphis: Bluff City Dist. Co. Falls Church: T. V. Workshop M ilwa.ikee: Team Electronics Memphis: Electronic Comm. Fredericksburg: Lafayette Radio, #75 Oshkosh: Team Electronics Memphis: Lavender Radio & TV Assoc. #76 Racine: Team Electronics #55 Memphis: Elect. Hampton: Electronic Sales Inc. Wholesale Schofield: Team Electronics #18 Millington: Millington Electronics Harrisonburg: Miles Music Co. Sheboygan: Team Electronics #65 Murfreesboro: Electronic Service Co. Lafayette Radio Elect, Lynchburg: Ivausac. Forward Electronics Nashville: Electra Dist. Co. Nee port News: Hannan Elect. Supply Union City: Bluff City Dist. Co: Newport News: Roanes Radio & TV WYOMING Service Gaspe): Fleming Supply Co. TEXAS Norfolk: Avec Electr. Corp. Casper: Hathaway Elect. Supply Arlington: Arlington Comm. Ctr. Norfolk: Lafayette Radio Arlington: Elect. Hobbies Inc. Norfolk: Radio Parts Dist. Co. CANADA Austin: Lafayette Radio Portsmouth: Distributors, Inc, Downsview, Ont.: Cesco Electronics Austin: Wholesale Elect. Supply Richmond: Avec Electr. Corp. Hamilton, Ont.: Western Radio Supply Bay City: Lafayette Assoc. Richmond: Lafayette Radio Ottawa, Ont.: Wackid Radio TV Labs Bellaire: Tele -Radio Inc. Richmond: Meridian Electronics ' Toronto, Ont.: Gladstone Electronics Brownsville: Electronic Center Roanoke: Avec Electronics Toronto, Ont.: Radio City Brownwood: Lafayette Radio Salem: Lafayette Radio Assoc. Montreal, Que.: l:esco Electronics Clear Lake City: Lafayette Radio Springfield: Springfield Audio Ctr. (3 locations). Corpus Christi: Ford Elect. Corp. Staunton: Southern Electric Corp.

GC GC ELECTRONICS ELECTRONICS DIVISION OF HYDROMETALS, INC. <212) ROCKFORD, ILLINOIS 61101` U.S.A. CIRCLE NO. 21 ON READER SERVICE CARD FEBRUARY 1972 101 19 MAC'S SERVICE SHOP Getting the Most from your Service Dollars By John T. Frye, W9EGV, KHD4167

I1' \VAS coffee break time at Mac's Service But be that as it may, it seems evident we're Shop. The owner and his redheaded as- going to be putting out more money for sistant, Barney, were seated side by side on service than we put out for manufactured the service bench, while Matilda, the office articles. Since such a high percentage of our girl, was enthroned on a high stool where income is going to be spent for service, it she could keep an eve on the front door. She would seem to behoove us to give some had baked and brought in a big platter of thought as to how we can get the best re- what- she called "man cookies"-huge sugar turn on those service dollars." sprinkled affairs almost the size of 45 -rpm "That seems logical," Matilda agreed. records-and these were disappearing fast "After all, we have magazines and books along with the coffee. devoted to explaining how to get the most "You know," Barney mumbled with a full value for the dollars we spend for things. mouth, "I don't see how a girl with such a_ Perhaps we need something similar to tell tart disposition can bake such sweet and people how to get the most value for money tasty cookies." spent for service." "Watch your smart Irish tongue or you'll "Say, whose side are you on?" Barney de- taste no more of them," Matilda retorted. manded, reaching for another cookie. "All right, you two," Mac interrupted "Don't forget we're in the service bsuiness." quickly; "I want your opinions about some- "\Ve, as well as everybody else, are also thing. Last night I read that in 1970 this in the consuming business,' Mac reminded country passed a milestone: for the first him. "But I like Matilda's idea about telling time the cost of services accounted for the customer how to get the most for his more of the gross national product than did service dollar. \Ve may not be able to help manufactured goods. What's more, the U.S. much with the plumber, electrician, dentist, Department of Labor predicts that by 1980 doctor, or automechanic but we should be seven out of every ten workers will be enable to tell how to get the most out of gaged in service rather than manufacturing." dollars spent for radio and TV service." "Ilow about that!" Barney exclaimed. "It looks like we're in the right business." Pick a Good Technician. "The first thing "I'm not so sure that's altogether good," to do is pick a good service technician," Matilda said thoughtfully. "It seems to me Barney led off, "and that's not easy. To coin the production of manufactured goods ac- a phrase, `Only another technician knows tually contributes to the real wealth of the for sure.' The layman lacks the technical country, while services make a necessary knowledge necessary to evaluate the work but more intangible and hard -to-measure a TV technician performs. He is likely to contribution. Some services, I'm sure, add be much more impressed by the simple nothing to the nation's wealth." problem of locating a shorted capacitor "I understand what's bothering you," quickly than he is by a brilliant job of track- Mac said with a nod. "I've some reserva- ing down an elusive intermittent condition tions of my own about an economy that's calling for complete mastery of theory plus becoming more and more service -oriented. a great deal of experience.

102 POPULAR ELECTRONICS Including Electronics World "However, there are some things a cus- AR guarantees its tomer can look for in selecting a service shop. Has it been in business long? is it published specifications well equipped? If the state has licensing, is there a license hanging on the wall and do At Acoustic Research we believe the technicians wear license badges? If the that the publication of complete state has a certification program, how many performance data on our high fi- of the shop technicians are certified? Are delity components is obligatory. any of them graduates of factory training Otherwise, our guarantee would schools or of other recognized training have little meaning. institutions? "Read the advertising carefully. If the Find out just what AR guarantees its word `Free' is tossed about recklessly, look that products will do. Mail the out. Are parts and labor both guaranteed or coupon below, and detailed tech- only parts? For how long? Finally, if the nical literature will be sent to you customer knows one honest andJ capable free of charge. service technician in any mechanical field, ask him to recommend a TV technician. A Acoustic Research, Inc. good mechanic usually recognizes and re- 24 Thorndike Street spects capable work in an adjacent field." Cambridge, Mass. 02141 Dept. PE -2 What Customer Should Do. "Now let me Please send measured performance data tell what the customer should do before he on AR products to calls us," Matilda urged. "The first thing he Name should do is get out his operator's manual and read it carefully. Is the set plugged into Address an active socket? is the antenna attached properly? Are the controls correctly set? Is CIRCLE NO. 1 ON READER SERVICE CARD the circuit -breaker closed? If everything checks out and the set still will not function, a service technician should be called. "Before calling, however, the caller Technical should get together pertinent information: what is the make, model, and serial number excellence of the defective unit? Is it connected to the cable or to an indoor or autdoor antenna? in electronics Exactly what is the complaint? Is it with the picture, the sound, or both? Is only the On our small, friendly campus color at fault? In what way is reception the emphasis is on Living as abnormal? Is this condition present on all well as Learning. Extra -curric- channels or on only some? Which ones? Is ular social activities, student the trouble always there or it is intermittent? clubs, a student operated radio If the latter is true, how soon does it appear station, student government, after the set is turned on? If it goes away new dormitory and a full sports by itself, when does that happen? Does any- program help provide a world thing you do to the set change the con- of your own in which to prepare dition? Did you see or smell any smoke for tomorrow. Associate Degree around the set? Was there a popping, snap- in Engineering Electronics. B.S. ping sound? When will you lie home so the obtainable. G.I. approved. technician can call?" "i iey, Matilda, that's pretty good," Barney admitted with grudging admiration. "\Vitt the answers to those questions, the technician should be able to make a shrewd guess as to the trouble and have proper service in- VALPARAISO TECHNICAL INSTITUTE formation and parts with him when he calls. Dept. PE, Yellowstone Trail, Valparaiso, Indiana 46383 That saves his time and the customer's money." CIRCLE NO. 48 ON READER SERVICE CARD

FEBRUARY 1972 103 "Yes, and the customer can save more sit over in a corner and watch, that's fine, time and money by having everything ready but a good way to squander her money is for that call," Mac suggested. "I mean all to keep peppering the technician with ques- the stuff should be removed from the top tions such as 'What is chat thing? What of the set; adequate lighting should be pro- makes it do that? How much longer will it vided; and the kids should be corralled take von to fix it? Are you sure it isn't the in another part of the house." color power tube as my cousin Willie "I lear, hear!" Barney applauded. "And thinks?' Neither should she regale the tech- the customer herself should not try to en- nician with a detailed recital of experiences tertain the service technician with a lot of she has had with other `incompetent and small talk. Anything that diverts his atten- crooked technicians.' She might be giving tion from what he is doing simply increases him ideas!" the time necessary to do it. If she wants to "\Vhen the job is done, she should receive a dated and itemized bill," Matilda added. "Before paving that bill she should rrS f make sure the set is operating satisfactorily ? on all channels. The original complaint Ur',, -j should be stated on the bill, especially if it was intermittent in nature. Then if thé 4h M KITS FEATURED IN trouble comes hack after the technician leaves, it will be a matter of record that POPULAR: the complaint was not corrected. On the other hand, the technician cannot be held ELECTRONICS responsible for an entirely new trouble that AND FROM OTHER SOURCES' shows up later." "That brings us to the matter of trusting Psychedelic Strobe. Light $17.50 the service technician," Mac said. "My "UT" Stereo Amplifier $80.00 own practice is to pick a man I think I .FET Preamp $44.50 ° can trust and the r to trust him until I am SCA Adaptor $14.50 that trust is misplaced. \Ve all Ultrasonic Alarm $37.25 convinced Regulated Powér Supply $39.50 know that a radio and TV service technician can deceive a customer in dozens of < Prices plus postage and insúrance, different ways if he is so inclined. \Ve also t Also: know that if he charges what his knowl-

Psychedella I Color Organ, Sonolite, edge is worth, he does not need to resort Nixie Readouts, Frequency Counters, to a Sports Timers, Ultrasonic Alarm, etc. to such shabby business make good living. Iluman nature being what it is, there is always a tendency to meet expectations. !WRITE FOR FREE CATALOG If someone obviously distrusts you and ¡ 'Southwest Technical Products expects you to try to cheat him, his hos- h 219 (PE) W. Rhapsody tility arouses your own, and there's always ' San Antonio, Texas 78216 the temptation to give him the business CIRCLE NO. 42 ON READER SERVICE CARD just to prove you can. If your ethics do not FREE 111tInlosh CATALOG and FM DIRECTORY Get all the newest and latest information on the new McIntosh Solid State equipment in the McIntosh catalog. In addition you will receive an FM station directory that covers all of North SEND TODAY! America. I McIntosh Laboratory Inc. e I 2 Chambers St.., Dept. PT272 Binghamton, N.Y. 13903 . o.. .. . t NAME ADDRESS 114 FM/FM STEREO TUNER CITY STATE ZIP MX and STEREO PREAMPLIFIER L CIRCLE NO. 30 ON READER SERVICE CARD

104 POPULAR ELECTRONICS Including Electronics World hermit this-and ours do not-von still do Build this magnificent not give hint any breaks. On the other hand, you have to be a dirty dog to take ad- Schober Theatre Organ vantage of a customer who trusts von and for only treats you with friendliness and respect. You're much more likely to throw in a $1730! 'Includes few little extra touches in servicing the finished walnut receiver of such a customer." console. Amplifier, speaker system, optional accessories Putting it all extra. Only Together. "Okay, let's put $1256 if you all this together," Matilda said, plucking a build your own pencil from Mac's jacket console. pocket and start- You couldn't touch an organ like this in a store for less than ing to jot shorthand on the hack of a service $3500-and there hasn't been a musical instrument with this vast variety of genuine Theatre Organ voices since the days tag. "Americans arc spending more money of the silent movies! If you've dreamed of the grandeur of for service than they do for authentic big -organ sound in your own home, you won't find merchandise. a more satisfying instrument anywhere-kit or no kit. That means getting the most for their You can learn to play it. And you can build it, from Schober Kits, world famous for ease of assembly without the slightest service dollars is becoming increasingly im- knowledge of electronics or music, for design and parts quality from the ground up, and-above all-for the highest portant. They can do this by (1) picking a praise from musicians everywhere. service shop as carefully as they do a new Send right now for your copy of the full -color Schober catalog, containing specifications of the five Schober Organ car or a new living room suite, (2) calling models, beginning at $499.50. for service only xvhen they are sure they need it, (3) having all pertinent information The sC/,o/,PI.Organ Corp., Dept. PE -40 at hand when they call for service, (4) hav- 43 West 61st Street, New York, N.Y. 10023 Please send me Schober Organ Catalog and free 7 - ing things ready for the technician when inch "sample' record. Enclosed please find $1.00 for 12 -inch L.P. record of he arrives, (5) allowing him to work with a Schober Organ music. minimum of distraction, and (6) trusting NAME him and his judgment. While we've been ADDRFSS thinking in terms of radio and TV service, CITY STATE ZIP the same L general principles apply to all CIRCLE NO. 37 ON READER SERVICE CARD kinds of service, from dealing with auto mechanics to doctors." QUICK -PICK Pat. Pend. "That's a good summary, Matilda," her Makes removal of transistors and capacitors employer said, "but now the coffee and cookies are all gone, perhaps we'd better from a "forest" of parts easy quit talking about sere ice and start prac- ticing it." "It sure is tough working for a doggone slave driver," Barney muttered, starting to gather up the coffee cups.

Precision Roofs

Seven (7) tools elanrp on over 25 different outlines of transistors or can capacitors. Therefore, it can he used on hundreds of types of transistors and capacitors. Makes an excellent heat sink while unsoldering or replacing parts. Permits more attention to he given the soldering operation. Will leare botl, hands free to unsolder the !earls. .4 slight pull on the Quirk-Piek trill re - more the part when the leads are free. Colored handles permit Quick size selection. Packaged in an attractive carrying case. 995 set 7 Picture streaked? Call Speedy TV Shop Lendell Products of tools postpaid for immediate service. 939 S. 7th St. DeKalb, Illinois 60115 CIRCLE NO. 27 ON (READER SERVICE CARD FEBRUARY 1972 105 'sill.] Í At LEAST! HOME PR* =

!EVERiYONE CAN I v , AND AFFORD. Model FC-100 k, rMlna N, WIRE$4925 Electronics Library Start your custom Burglar/Hold-up/Fire Alarm System with the FC-100. IC PROJECTS FOR THE AMATEUR & Add on Sensors, Alarms EXPERIMENTER and Accessories to suit your 1- own needs. This book, put together by the staff of 73 Mag- "Do -it -Yourself" Installers azine, offers the reader an opportunity to Handbook included. No technical knowledge needed - learn about integrated circuits by doing. It con- No soldering. tains complete details on the operation and 100% Professional in Design, Reliability, construction of 35 IC projects for the hobbyist, Performance. experimenter, and student. Detailed are such items as a digital counter, audio mixer, signal 'Fail Sate'-SYSTEM BY EICO and marker generators, code -practice oscillator, in "Do-it-Yoursell."Home Protection A New Concept audio filter, ac switches, and many more. In r. FREE 32 PAGE. EICO CATALOG addition to schematic diagrams, the book is For latest catalog on EICO Test Instruments, Stereo, EICOCRAFT illustrated with photographs, waveforms, and Projects, Environmental Lighting, Burglar/Fire Alarm Systems. and name of nearest EICO Distributor, check Reader Service some printed circuit board drilling and etching Card or send 25c for First Class mail service.. /7 guides. EICO, 283 Malta Street, Brooklyn, N.Y.11207 C0 7 Published by Tab Books, Blue Ridge Sunlnlit. CIRCLE NO. 16 ON READER SERVICE CARD PA 17214. 192 pages. 86.95 hardbound, $3.95 .softbo timid. r STEREO IN YOUR HOME ANOTHER SUPERB VALUE by Walter G. Salm This book reviews many of the developments in from stereo since it was popularized in the late 1950's. It covers the entire spectrum of stereo Olson and offers tips on how to install systems, make Electronics recordings, evaluate equipment, and what to ONLY look for when buying equipment. Discussions are included on how stereo and tape recorders work. commercial recordings are made, tapes and records are produced, and FNi and TV X18 antennas can be used in a stereo system. For SOLID STATE those interested in 4 -channel stereo, a discus- DC POWER sion of 8 -track cartridges is included. SUPPLY Published by Vertex, Auerbach Publishers, Inc.. 1101 State Rd., Princeton, A'J 08540. Hard Now convert your Auto Tape Player, Radio or CO to cover. 2.31 pages. 88.95. house current. Delivers a well filtered and stabilized RCA RECEIVING TUBE MANUAL, RC -28 12 volts DC @ 2 amps from 110-120 volts AC. Fuse protected against overloads or shorts. Containing some 100 pages more than in the Olson Electronics, Dept. 12, 260 S. Forge St., previous edition, this revised and updated man- Akron, Ohio 44308 ual corers more than 1600 tubes. Included o I enclose $18, plus $1 for postage and handling. for the first time a e technical data on indus- Send me the BA -161 DC Power Supply. trial receiving tubes and new entertainment - o Send me the next seven issues of the Olson type receiving tubes. Data for monochrome Catalog, without cost or obligation. FREE and color TV picture tubes are presented in Name chart form. Comprehensive text and circuit Address sections, the latter containing 35 schematic City diagrams and parts lists, are included as always. State Zip Published by RCA Commercial Engineering, L Harrison, N) 07029. Soft cover. 784 pages. CIRCLE NO. 32 ON READER SERVICE CARD $2.50.

106 POPULAR ELECTRONICS Including Electronics World The Cobra 880 Base Station - either Channel 9 or the selected channel, Solid State CB Two Way Radio the receiver automatically locks on the with Exclusive Channel 9 Scan -Alert active channel. The receiver resumes New Cobra 880 combines a lot of good scanning after the transmission is completed. And if ideas into one package. It. combines you want to respond to a Cobra's famous rugged construction with Channel 9 call, just slide one switch, with- total solid state design to give long life out upsetting your channel selector set- and reliable performance. Adds AC or DC ting. The Cobra 880 combines normal and operation to keep working in all power emergency guarding-and makes it easy. situations. Leaf digital with clock auto- Here are some more good ideas matic turn -on and turn-off features. Acid in Cobra 880: puts you on guard-with Scan -Alert! the With Scan -Alert, you'll be able to work 23 Channel operation with crystal your own channels and guard Emergency frequency synthesizer RF Gated Noise Channel 9-at the same time. Blanker and Automatic Noise Limiter Scan -Alert is a Cobra exclusive that Illuminated Channel Selector O Com- alternately changes the channel of the bination Relative Power, SWR and S receiver from your operating channel to meter O Dual Conversion Receiver, with Emergency Channel 9. The Channel FET RF stage Dynamic microphone, Indicator light and the Channel 9 indi- with coiled cord and plug P.A. and cator light flash alternately. As Scan - external speaker jacks O Transmitter Alert automatically switches between modulation indicator light Meets FCC frequencies. When a signal is received on requirements $22995

1 \J

GOac,A Bao

COBRA 880 Product of DYNASCAN CORPORATION 1801 W. Belle Plaine Chicago, Illinois 60613

See your local GB Dealer or write us for more information. CIRCLE NO. 6 ON READER SERVICE CARD

FEBRUARY 1972 107 More kits than ever...over 354.,.a11 in your The most advanced color TV kit we've ever offered. ..P -...,-.

é ct

Magnificent Mediterranean Console. Here's the finest TV cabinet we offer, a perfect choice for a GR-900. Has -deep, grained pecan veneers on hand -rubbed furniture grade hardwood solids.Two - scalloped double -hinged doors hide the 7V screen when not in use. Assembled GRA-405-25, 100 lbs.....179.95* "

The new Heathkit GR-900 25V Color TV has UHF/VHF detent - Wireless Remote for your GR-900. more features The ultimate in armchair viewing. Gives you tuning & varactor UHF tuner, angular tint control - eight function across -the -room control of than any other color TV kit! Better performance than any other set. on/off, three preset volume levels, power- tuning lup or down), color, tint, UHF/VHF UHF/VHF detent power tuning. Push a button and you scan the channels in either direction channel selection. Also activates Custom with detest action locking in on VHF channels 2-13 and any 12 preselected UHF stations. Wall Mount doors.. A pushbutton selects either UHF or VHF mode, and a lighted dial indicates tuner position. Kit GRA900.6, 6 lbs. 79.95* And you can have full remote -control selection too for just a few dollars more. New voltage -controlled varactor UHF tuner and specially designed VHF tuner with MOS Field Effect Transistor contribute to better fringe -area reception, increased sensitivity. New angular tint control. A switch now gives you either "normal" or "wide angle" color demodulation to reduce tint and flesh tone change when changing stations and when programs change. Other deluxe features include "instant on" operation with override for conventional on/off operation; automatic fine tuning; adjustable tone control, and an output for playing TV audio through your stereo hi/fi system. Exclusive Heath MTX-5 ultra -rectangular tube. It's the largest color screen you can buy anywhere, with a full 25 inch meas. diag., 315 sq. in. viewing area. You see virtually everything the station transmits, in the corners and at the sides. The specially etched face plate cuts glare, and reflection, increases contrast without sacrificing brightness, and each dot is projected through a matrix screen to stand out crisply against a solid black background. Modular solid-state circuitry. Plug-in circuit boards and plug-in transistors make assembly, adjustment and servicing easy. There are 46 transistors, 57 diodes and four ICs - making this one of the most reliable sets we've ever designed. noise Other features include automatic chroma control, adjustable video peaking, adjustable New Custom Wall Mount Touch button on limiting and gated AGC. the flame or on your Heathkit Remote unit and the folding tambour doors Exclusive Heath self-service built-ins. Your Heathkit GR-900 includes built-in dot generator, Control open to reveal your color TV. Kit includes -out convergence panel for set-up and periodic adjustments. A handy volt -ohm meter tilt everything needed to build your Heathkit in helps you check your work during assembly, and can be used in included the circuitry GR-371MX or GR-900 into a wall. the manual for any servicing. Like all Heathkit color TVs, the GR-900 gives conjunction with Kit GRA-402-25, walnut finish, There are four beautiful Heath cabinets to choose from you complete installation flexibility. 50 hm 114.95* electronic wall mount with hide -away tambour doors. Or you can cus- plus the new built-in Kit IGtA.407-25, unfinished, We think you'll agree, the GR-900 is truly the most impressive color tom install your GR-900. 50 lbs - 109.95' receiver we've ever offered. Kit GR-900, TV less cabinet, 125 lbs. 599.95* World 108 POPULAR ELECTRONICS Including Electronics FREE '72 HEATIIKIT Catalog The better -than -ever '72 Heathkit Catalog has the world's largest selection of fun -to -build, money -saving electronic kits...including color j TV, stereo/ hl fl, organs, home appliances, 3 n radio ports- 11, f000 1 engine tune-up tools, control, i bles, shortwave, marine gear, metal locator, instruments, hundreds more. If you --1111911111447 seeingdon't'' 1 %11) have this catalog, you've missed _ over 50 new kits, introduced since the last edition. Send today for your free copy. ¡

New Heathkit Digital Multimeter 229.95`

A kit -form multimeter that meets lab specs. Has 31/2 digits for 100 uV resolution on the 200 mV range, 1V on 1000 V. Five overlapping ranges measure voltage from 100 uV to 1000 V on DC (either polarity); 5 ranges cover MOW measure 100 nA to to 500 Von AC; 10 ranges r: 2A AC or DC; and 6 ranges measure resistance > from 0.1 ohm to 20 megohms. Input impedance is approx 1000 megohms on 2V range, 10 megs on higher ranges, with overload protection Agy built-in. DC calibrator supplied permits 0.2% d accuracy without external equipment. Can be 4 n lab calibrated to 0.1%. For lab performance at . your IM -102 today. 4 a budget price, order ® ® Kit IM -102, 9 lbs. 229.95* ^-

e ¢.

The most powerful' and sensitive stereo receiver they've ever tested. experts as the best Heathkit AR -1500 AM/FM/FM-Stereo Receiver - ranked by independent watts 4 ever. Here's 180 watts dynamic music power, 90 watts per channel into 8 ohms, 120 per channel into 4 ohms. Less than 0.1% intermod distortion, less than 0.25% harmonic I linearity, separation, and O'.)- IN a) ' distortion. FM selectivity greater than 90 dB, outstanding phase low distortion result from two computer -designed 5 -pole LC filters. A 4 -gang 6 -tuned circuit image front end offers rock -solid stability, 1.8 uV sensitivity, 1.5 dB capture ratio and 100 dB adjustable and IF rejection. Automatic FM squelch is both noise and deviation activated, fully New Heathkit 10 MHz for sensitivity. MOSFETS in the RF and Triggered Sweep Scope. ZZ9.95* The AM section, overlooked in most receivers, boasts two dual -gate LC fitter in the IF, and broad -band detector Here's a five -inch triggered sweep scope at Mixer stages, one J-FET in the oscillator, 12 -pole and high-fidelity per- a price you can't afford to pass up. Has for good overload characteristics, proper AGC action, no IF alignment wiring har- DC -10 MHz response, calibrated attenuator, formance. The AR -1500 is an easy kit to build, ten plug in circuit boards, two AC -DC fun. 50 ns sweep rate with magnification, nesses and extensive use of pre-cut wiring with installed clip connectors make assembly 50 mV It's the ideal coupling, sensitivity. Built-in test circuitry uses the signal meter to make resistance and voltage checks as you go. instrument for general service and design the set features include Black Magic panel lighting that hides the dial markings when work ...and its quality design, easy assembly, Other tuning; pushbutton function controls; outputs for two separate speaker simple operation and self-service capability is not in use; flywheel of FM multipath; inputs for phono, tape, make the Heathkit 10-103 one of the greatest systems, bi-amplification, oscilloscope monitoring level The AR -1500 is the scope values on the market today. Order one tape monitor and auxiliary sources - all with individual controls. for your shack, shop, lab or classroom, now. critics choice, and with no reservations, the best stereo receiver we've ever designed. 379.95* Kit 10-103, 37 lbs. 229.95' Kit AR -1500, less cabinet, 42 lbs. 24.95* ARA -1500-1, walnut cabinet, 6 lbs.

Send for your FREE 1972 Heathkit Catalog today HEATHKIT

CALIF.: Ana = HEATHKIT ELECTRONICS CENTERS- ARIZ.: Phoenix, 2727 w. Indian School Rd.; -r HEATH COMPANY, Dept. 10.2 Schlumberger 2309 5. Flower St.; Red- 49022 heim, 330 E. Ball Rd.; El Cerrito, 6000 Potrero Ave.; Los Angeler, Benton Harbor, Michigan (La Mesa), 8363 Center Dr.; Woodland Hills, wood City, 2001 Middlefield Rd.; San Diego FREE Heathkit Catalog. 4705 16th Please send 22504 Ventura Blvd.; COLO.: Denver, 5940 W. 38th Ave.; FLA.: Miami (Hialeah), W. I Downers Grove, I is S plus shipping. Ave.; GA.: Atlanta, 5285 Roswell Rd.; ILL.: Chicago, 3462.66 W. Devon Ave.; Enclosed Rockville, 55421 224 Ogden Ave.; KANSAS: Kansas City (Mission), 5960 Lamar Ave.; MO.: Please send model(s) Nicholson lane; MASS.: Boston (Wellesley), 165 Worcester 5t.; MICH.: Detroit, 18645 W. 101 Shady Oak Rd.; Name Eight Mile Rd. & 18149 E. Eight Mile Rd.; MINN.: Minneapolis (Hopkins), MO.: St. Louis, 9296 travois Ave.; N.J.: Fair lawn, 35.07 Broadway (Rte. 4); N.Y.: Buffalo 1 Address Dr.; New York, 35 W. 45th St.; Jericho, L.I., 15 Jericho Turnpike; I (Amherst), 3476 Sheridan City State lip OHIO: Cincinnati 10133 Springfield Pike; Cleve. I Rochester, Long Ridge Plaza; (Woodlawn), to change without notice. Blvd.; Pittsburgh, 3482 Wm. Penn Prices & speciftrations subject land, 5444 Pearl Rd.; PA.: Philadelphia, 6318 Roosevelt 'Mail order prices; F.O.B. factory. CL -029 R Hwy.; TEXAS: Dallas, 2715 Ross Ave.; Houston, 3705 Westheimer; WASH.: Seattle, 2221 Third Ave.; WIS.: Milwaukee, 5215 fond du Lac. r_ CIRCLE NO. 24 ON READER SERVICE CARD 111 FEBRUARY 1972 Electronics. The antenna rotor system has many of the best features of rotors in the company's line. The rotor itself is housed in a heavy-duty die-cast aluminum enclosure, painted gold to match modern color antennas. Quick unit mounting is made possible through positive -grip U -bolt clamps on the aluminum housing. And a positive braking system is featured. The control is fully automatic and of the same type used with the well-known AR -22 rotor. After New Products, the desired direction is set, the unit stops automatically and with greater accuracy. The dial face is illuminated when the systeul is in WELTRON CASSETTE RECORDER MOTOR operation. Address: Cornell-Dubiler Electronics, Recently introduced by the Weltron Co. is 150 Avenue "L", Newark, NJ 07101. a new do replacement motor for cassette recorder and player decks. Model 70-70(1 operates TOYO 4 -CHANNEL CARTRIDGE PLAYER on Ci 9 volts dc with a clockwise rotation. The Four discrete channels of sound, through four universal cassette motor operates at 232( rpm separate amplifiers, are featured in the Model at 6.5 volts or 2400 rpm at 9 volts. Address: 707 "(audio" cartridge tape player made by Weltron Co., 514 E. Peabody St., Durham, NC 2770'1

CADCO SINGLE -CHANNEL FM PREAMP A high -gain, ultralow-noise single -channel FM preamplifier, Model IPA-SCA-FM, has been announced by Cadco Systems. This is a 22 -dB gain indoor mounting single -channel amplified filter designed to boost weak off -the- '1'oyo Rodio Co. of America, Inc. The system is also iulb compatible with existing 2 -channel stereo material, and with the addition of '['ovo's Model QC -1 4 -channel decoder, will CADCU matrix out the ambience information to provide

{ the two rear channels for 4 -channel stereo from moon ,PA-SCA-17.1 AMPIIFI.TER, a 2 -channel source. Featured are pushbutton mode selector, automatic and manual program selection for both 2- and 4 -channel operation, rear balance control, and phase selector switch air signal levels for main channel and SCA to keep front and rear speakers in -phase m ith channel uses. The preamplifier has a 1.:3 -dB each other. An optional cassette adapter is also maximum noise :3 figure and dB bandwidth available to allow the Model 707 to play con- products of ±500 kHz. The unit has its own ventional cassettes. Address: To\o Radio Com- built-in 117 -volt ac power supply and 75 -ohm pany of America, Inc., 1842B W. 169th St., input and output. Addess: Caddo Systems, Gardena, CA 90247. 4444 Classen Blvd., Oklahoma City, O1: 7:3118. CB UNIT FROM DYNASCAN LAFAYETTE ELECTROSTATIC HEADPHONES Dynascan Corporation has introduced a new The Model F-2001 electrostatic stereo head- mobile CB two-way radio with an exclusive phones available from Lafayette Radio Elec- emergency channel 9 "Scan Alert." This feature tronics Corp. deliver three octaves of sound enables the operator to simultaneously monitor beyond conventional phones. The F-2001 has channel 9 and any of the other 22 channels of a self -energizer with speaker/phone switch and his choice. The Cobra 28 has a full .5 watts of color -coded speaker cables. The energizer con- input power with Dyna-boost speech com- verts audio signals into dc polarizing voltage's pression, r -f noise blanker, automatic noise which charge the diaphragm. Also included is limiter, PA system output, delta tune, channel an adjustable vinyl cushioned headband. Fre- quency range of the headphones is .5 Hz to :35,000 Hz; nlpedance 4-16 ohms. Address: Lafayette Radio Electronics, 111 Jericho 'Turn- \ . f t - . - pike, Syosset, NY 11791. IT? 1411 CORNELL-DUBILIER ANTENNA ROTOR A new economy -priced rotor, the Model AR - 20, has just been introduced by Cornell-llulºilier .`1s

112 POPULAR ELECTRONICS Including Electronics World indicator lights, power/S meter, as well as IC's and FET's to reduce cross -modulation. CONTROLLED The unit measures 2 x 6" x 8A" and weighs QUALITY 41/. pounds. It 'operates on 12 volts de, only but may be used with an optional power pack CRYSTALS by on 117 -volt ac. Address: Dynascan Corp., 1801 \V. Belle Plaine Ave., Chicago, IL 60613.

RUSTRAK AC VOLTAMP RECORDER r1;,;'CflVSTEK! that measures both ac A low-cost recorder Crystals voltage and ac current has been introduced as The "On -Channel" the Model 2:30 by Rustrak Instrument Die. of FOR Culton Industries:Inc. The recorder is furnished CITIZEN BAND a leather with a clamp -on transducer and 23 Channels and "Mars" HAM OPERATORS Commercial 2 -Way Marine -Monitor .11 See your Distributor for Speedy "Zip Certificates" carrying case witth handle. The single instrument is designed to read and record three vol- '3'CBVSTEfl tage and three current ranges. Voltage ranges 60 Hz with formerly Texas Crystals are 0 to 150, :300, and 600 volts at Div. of Whitehall Electronics Corp. an accuracy of :3 percent full-scale. Current 1000 Crystal Drive 4117 W. Jefferson Blvd. ranges are 0 to 25, 100, and 300 amperes at Fort Myers, Florida 33901 Los Angeles, California 90016 60 Hz with accuracy of four percent full-scale. CIRCLE NO. 11 ON READER SERVICE CARD The clamp -on transducer has a built-in dial to easy switching of ranges and functions. facilitate Y ear The recorder, plus transducer, clip leads, carry- Our 51st 1 rolls of paper, is priced at ing case and 2 t.AFAY;j Instrument Div., tros o 8159.00. Address: Bnstrak Gulton Industries, Inc., Nlunicipal Airport, Manchester, NI 10310:3. vµt /

LOW-COST LASERS FROM METROLOGIC SrETorm Your One Dependable aluminum cathode, helium -neon GW Two new For lasers developed by Metrologic Instruments Siurce feature longer life and low cost, thanks to the Everything In aluminum cathode which provides constant F Electronics power output and high beam positional stability. The tubes, designated MT 710 and MT 711, have power outputs of 1.5 m\V and 2.4 n1W, ° respectively. The company is guaranteeing L., FA ' r1 9000 hours or one year of operation with the 1972 CATALOG 720 new units. Address: \letrologic Instruments, Cartridge and Tape Inc., 14:3 Harding Ave., Bellmawr, \ 108030. 4 -Channel Stereo Equipment Players CB Gear PA Systems Tools Cameras Auto Accessories Books musical Instruments TENNA 2 -WAY MOBILE RADIO and Amplifiers An inexpensive emergency 2 -way radio for motorists was recently announced as their Lafayette Radio Electronics Dept. 35022 "HELP 9" by Teniur Corp. The HELP 9 P.O. Box 10, Syosset, L.I., N.Y. 11791 a 'practical method of providing represents Send Me the Free 1972 Catalog 720 35022 security and safety by providing 2 -way voice communication on channel 9 of the Citizen's Name Band reserved by the Federal Communications Address Commission for emergency calls. It is de- City in immediate con- signed to place the motorist State ____ Zip tact with help in cases of accidents, car failure, or criminal action. IIELP 9 features simplicity CIRCLE NO. 26 ON READER SERVICE CARD 113 FEBRUARY 1972 of operation, with a single on/off/volume control. Transmission or receipt is governed by a thumb switch on the microphone. Address: Tensa Corp., 19201 Cranwood Pkwy., Cleve- land, Oil 44128. AN ASTRO PLANE IS LOVE HEATHKIT CASSETTE DECK KIT The 11ea/h Company has announced their entry into the cassette age with the introduction of their Model AD -110 cassette deck kit. The All -110 has six pushbuttons that control all

THE PATENTED CB

"OMNI" °-I BASE ANTENNA $29.95 tape functions, separate level controls and meters, tape counter, automatic shutoff, and record safety interlock. Technical specifications match y- or exceed those of many open-ree machines T ¡sic `r1;: - 33-35 WEST FULLERTONAVENUEo 394 ADDISON. ILLINOIS 60101 that operate at ips. The all -solid-state cir- AVANTI cuitry employs a two -transistor do motor regu- RESEARCH & DEVELOPMENT, INC. ' lator and an IC voltage regulator in the ;,..,. 5 'THE PACESETTER IN HIGH PERFORMANCE ANTENNAS amplifier circuit. The transport mechanism comes CIRCLE NO. 4 ON READER SERVICE CARD preassembled for easy kit assembly. Optional microphones a e also a ailahle. Address: Ileath Co., Benton harbor, NII 49022.

r LINER SERVICE PIONEER REVERBERATION AMPLIFIER VHF, UHF, FM or IF Modules ... To supplement existing stereo systems, U.S. Pioneer . . . All Makes Electronics Corp. offers the Model SR -202\V solid-state reverberation amplifier. mast hr. Service!

1 YEAR GUARANTEE

VHF -UHF -FM $ 9.95 UV -COMB. $16.95 IF -MODULE $12.50 Major Parts charged at Net Price P.T.S. is overhauling more tuners for more technicians than any other tuner company in the world! LIKE TO DO IT YOURSELF? Send one Dollar (redeemable) for our The rested) amp blends signals from 60 pages of top information music sources with a reverb effect that greater TUNER REPLACEMENT GUIDE AND adds PARTS CATALOG acoustic realism. The SR -202W can be used to For fastest service, send faulty tuner with supply a variety of effects. A tubes, shields and all broken parts to: five -position mode selector can be set to add reverb to speakers PTS 'ELECTRONICS, INC. onh or to the recording sound of a tape deck. " cuiaioe 7.i4 Sewse" Revell) can be used HOME OFFICE- without altering the sound /lox 272 Bloomington, Ind. 47.101 Tel. 812. 824.9331 recorded on tape call W EST- and be omitted simply by Box 41354 Sacramento. Calif. 95841 Tel. 916. 482.6220 setting the selector to off. A -pane] SOUTH - front indi- 1100 7332 Longview. Tex. 75001 Tel. 214. 753.4334 cator shows the amount SOUTHEAST- of reverberation se- Box 6881 Jacksonville. Fla. 32205 Tel. 904. 389-9952 lected a EAST- by setting separate time control. Ad- Box 3180 Springfield. Glass. 01103 Tel. 41:1, 734.2737 dress: Pioneer 178 MOUNTAIN- Electronics, Commerce Rd., S,. 4245 Denver, Colo. 80204 Tel. 303. 244-222818 Carlstadt, NI 07072. CIRCLE NO. 33 ON READER SERVICE CARD 114 POPULAR ELECTRONICS Including Electronics World THE ONLY CB MICROPHONE MADE ESPECIALLY FOR ttM/i TAN$CIVS

The microphone that carne with your AM/SSS set wasn't made for single side band. Turner makes one thai is. The only one. We call it Side- kick 100. Sidekick 100 has a dynamic cartridge with an integrated -circuit: amplifier which provides low impedance and a perfect match for the latest AM/SSB transceivers, You'll get full modulation and a powerful signal every time. l Sidekick 100 also is the best match any AM transis- per for conventional torized transceiver on the market. This handsome new microphone is chrome and black with all the features it takes to provide out- die-cast metal , standing performance. Rugged, case. 300-3,000 Hz frequency response range. Touch -to -talk front bar with slide lock for extended transmission. Self-contained 9 -volt battery. Output level -23 db. Get more out of single side band. Put the Sidekick 100 into it. Write'for details. Turner Division. Conrac Corporation. 909 Seventeenth Street N.E., Cedar Rapids, Iowa 52402. Telephone (319) 365-0421.

TURNER DIVISION C o N R A C CORPORATION

CIRCLE NO. 47 ON READER SERVICE CARD

115 FEBRUARY 1972 CHEMTRONICS 1912 CATALOG Complete descriptions, general and unusual applications, illustrations, tables, and pricing for all products are featured in the 12 -page, 1971- 1972 catalog from Chenrironics Inc. Listed a e such items as tuner sprays, circuit coolers, in- sulating sprays, contact and control sprays, cleaners and conditioners for tape heads, electronic glues and cements, solder, and paint sprays. Address: Chenitronics Inc., 1260 Ralph New Literature) Ave., Brooklyn, NY 112:36.

AMPEX CASSETTE BROCHURE BEARCAT MONITOR BULLETIN A 6 -page brochure, No. T694, describing the The all -new "Bearcat Ill" scanning monitor :362 series extended -frequency blank audio cas- receiver is illustrated and described in a two - settes is available from Ampex Corp. The :362 page bulletin ( No. 1071) available from E/eclro series is a high-performance cassette that de- Corp. The bulletin fully describes the F\I pub- livers up to six times more sound in the upper - lic safety/business hand receiver and presents frequency range than do standard cassettes. information on plug-in r -f modules and crystals. Address: Ampex Corp., Stop 7-1:3, 401 Broad- A complete list of technical specifications and way, Redwood City, CA 9406:3. a price/band coverage table for all one- and two -band models of the Bearcat Ill are also SPERRY METERS AND TESTERS provided. Address: Electra Corp., :300 South Country Line Rd., Cumberland, IN 46299. A. W. Sperm/ Instruments Inc. recently announced the release of their latest comprehen- DESCRIBES 21 INSTRUMENTS sive folder, No. PF -45. Described in the folder DYNASCAN is the company's complete line of snap -around D!/rascan Corp. has just released a new catalog volt -ohm -ammeters, master electrical kits, mul- describing the Beth line of test equipment for titesters, and accessories. Address: Sperry In- electronics servicing, laboratory, and industrial struments, 245 Marcus Blvd., Hauppauge, NY applications. A total of 21 instruments, en- 11787. compassing a wide range of equipment from a 1(10 percent Mutual Conductance Tube Tester RCA LASERS AND IR DIODES to a new DC-to-10-\IIIr triggered sweep "Gallium -Arsenide Injection Lasers and Infra- oscilloscope, are described. \ddress: Dyna- scan, 1801 \V. Belle Plaine Ave., Chicago, IL red -Emitting Diodes" catalog ( OPT -100 \ ) has just been made available by RCA So/id Stale 6061:3.1:3. Div. It contains data on the RCA line of room - ALCOLITE temperature infrared -emitting diodes, single - INDICATOR SPECIFICATIONS diode lasers, injection -lase arrays, and stacked - Specifications, ratings, and physical dimensions diode lasers. Data on gallium -aluminum - of the Alcolite "Elfin" 7 -segment neon in- arsenide laser diodes and arrays, and cryogenic dicator are detailed in Catalog EL -77 put out laser arrays, are also included in the I2 -page by Alco Electronic Producis, Inc. Of special revised catalog. Characteristics, operating con- interest is the section describing Elfin New siderations, and applications of all listed de- Generation Hybrid Circuits for Cold -Cathode vices are given. Address: RCA Commercial Neon Displays. Address: Aleo Electronic Prod- Engineering, Harrison, NJ 07029. ucts, Inc., Lawrence, MA 0184:3.

Sonar LISTEN TO: POLICE, FIRE, & WEATHER REPORTS! for lndusttlialCommercial,.Utiiity & Govt. Use. SENTRY 3 CHANNELS BROADCAST BAND CRYSTAL CONTROLLED _ Designed and engineered for simplicity of operation, compact

enough to fit a shirt pocket yet pówe,rful enough to deliver a . VHF MONITOR clear clean signal-it's dependable OperatesO on three crystal -controlled VHF channels plus broadcast band Adjustable squelch Completely solid state for long life use Visible RECEIVERS WITH battery indicator to show battery condition at all times Built . ADJUSTABLE SQUELCH in antenna í5r/e H x 21/2"W x 13í," D.Wt. 11' oz. N. Y. 11207 With Battery, - j. SONAR RADIO CORP., 73 Wortman Ave., Bklyn, Á E Earphone, & Ls H IOSTpB`E s óClCt S11E Please send information on VHF Monitor Receivers. less Crystals 95J $ Dept. 426 1i . KE Name 9(h I $5yÓ0 ea. VatS Address FR103SA FR-106SA (IN FOUR\I // (150-175 MHz)I MHz \ FRED. `3 City State Zip 30-50 ead ------CIRCLE NO. 40 ON READER SERVICE CARD

1 i6 POPULAR ELECTRONICS Including Electronics World ELECTRONICS MARKET PLACE

at NON -DISPLAY CLASSIFIED: COMMERCIAL RATE: For firms or indi- GENERAL INFORMATION: First word in all ads set in bold caps viduals offering commercial products or services, $1.50 per word no extra charge. All copy subject to publisher's approval. All MUST (including name and address). Minimum order $15.00. Payment advertisers using Post Office Boxes in their addresses number must accompany copy except when ads are placed by accredited supply publisher with permanent address and telehone advertising agencies. Frequency discount: 5% for 6 months; before ad can be run. Closing Date: 1st of the 2nd month pre- !e+'. 10% for 12 months paid in advance. READER RATE: For individ- ceding cover date (for example, March issue closes January to Hal Cymes. POPULAR ELECTRONICS uals with a personal item to buy or sell, $1.00 per word (includ- Send order and remittance Avenue, New York, ing name and address.) No minimum! Payment must accompany Including ELECTRONICS WOIRLD, One Park MY. DISPLAY CLASSIFIED: 1" by 1 column (25/a" wide), $185.00. New York 10016. 2" by 1 column, $370.00. 3" by 1 column, $555.00. Advertiser to supply cuts. For frequency rates, please inquire.

MECHANICAL, ELECTRONIC devices catalog 100. Greatest Values FOR SALE -Lowest Prices. Fertik's, 5249 "D", Philadelphia, Pa. 19120. SENCORE, B&K Test Equipment Unbelievable Prices. Free Catalog Radio, 265 East 149th Street, Bronx, FREE! bargain catalog. Fiber optics, LED's, transistors, diodes, and Price Sheet. Fosdham rectifiers, SCR's, triacs, parts. Poly Paks, Box 942, Lynnfield, N.Y. 10451. Mass. 01940. ELECTRONIC Ignition. Various Types. Information 100. Anderson N.H. 03239. GOVERNMENT Surplus Receivers, Transmitters. Snooperscopes, Engineering, Epsom, Radios, Parts, Picture Catalog 250. Meshna, Nahant, Mass. 01908. BU/LO YOUR OWN SPACE-AGE TV CAMERA ROCKETS: Ideal for miniature transmitter tests. New illustrated e OLY Kte t s0LID5TATE CAMERA KITI Ideal fa experimenle,s, catalog. 250. Single and multistage kits, cones, engines, launch- harm, ecmoli ,doetry, etc. High quality flaked by aw ers, cameras, information. Fast six yes ml lob Geld bung Folly Gaaaueed Connects trackers, rocket aerial technical to ay T. o., wishoot worifrcaeá, ,yep4 exp.cm,mmlim service. Estes Industries, Dept. 18-K, Penrose, Colorado 81240. mmd Ikil 51.18, Seria D creolero wish rid,em $149.10 patesid aerobe. in USA 6 Goode pass sicken tib $116.550) or WRITE for CATALOG. Free. ¡ PHONE LOWEST Prices Electronic Parts. Confidential Catalog DIAL aoa-^earn KNAPP, 3174 Ave. Largo, Fla. 33540. 8TH S.W., Obey ale- kin, pan and plans avaibNe including saxer WI, lave J seómma kit et. Ml. tail* viccm tubes, tome. pions, radio Machine, 68731 WE SELL CONSTRUCTION PLANS. TELEPHONE: Answering 1301 BROADWAY ATV Research DAKOTA CITY, NEBR. Speakerphone, Carphone, Phonevision. Auto Dialer, Touch Button Dialer, Central Dial System. TELEVISION: $35.00 Color Converter, ELECTRONIC COMPONENTS -Distributor prices, Free catalog. Box Micro- Video Tape Recorder, $25.00 Camera. HOBBYIST: Electron 2581. El Cajon, California 921)21. scope, 96 Hour Tape Music System, Ultrasonic Dishwasher, Radar -Oven. Plans $4.95 each. NEW ITEM: $75. Electronic DEALERS WANTED! Citizens Band, AM, SSB, Two-way Radios & Pocket Calculator, $7.50. COURSES: Telephone Engineering Accessories. USA and Export models. We ship around the world. $39.50. Detective Electronics $22.50, Integrated Circuit Engi- Send letterhead to: Baggy's Radio P.O. Box 778, 6391 neering, $49.50. NEW SUPER HOBBY CATALOG plus year's sub- Westminster Ave., Westminster, Ca. 92683. 714-894-3301. scription to Electronic New Letter AIRMAILED $1.00. Don Britton Enterprises, 6200 Wilshire Blvd., Los Angeles, Calif. 90048. AMATEUR SCIENTISTS, Electronics Hobbyists, Experimenters, Students ... Construction Plans -all complete, including draw- ings, schematics, parts lists with prices and sources ... Radar- radar. Detect motion of peo- JETCO ELECTRONIC INDUSTRIES, 1NC. Build your own ultrasonic doppler Dept. PEC, 3933 Barranca Dr.. El Paso. Texas 79935. ple, automobiles, even falling rain drops. Transistorized, uses 9 Tele- battery -$450 . . . Long -Range "Sound FIND COINS -GOLD -RELICS -TREASURE... volt transistor Y scope" -This amazing device can enable you to hear conversa- metal locators by JETCO! '' Nve t tions, birds and animals, other sounds hundreds of feet away. Lightweight Very directional. Transistorized. Uses 9V battery -$3.50 . Easy to Use priced from^- yri` 1,:,E1s=r Robot Man -Moves hands and arms -53.50... Or send 250 coin Comes Complete Other items include Psyche- Made in USA (no stamps) for complete catalog.

. . . 46 projects. 5 yr. Guarantee delic strobes, light shows, lasers different Immediate Delivery! , r Technical Writers Group, Box 5994, State College Station, FREE 4 Write for Catalog. Raleigh, N.C. 27607.

ANTIGRAVITY, experiment and theory; Rushed -$2.00. U.S. In- INVESTIGATORS, latest Electronics Aids. Free Literature. Clifton, quiries. Intertech 7A5, Box 5373, Station -F, Ottawa, Canada. 11500-L NW 7th Ave., Miami, Florida 33168. LEARN the facts of electronics and your privacy. Send for the ELECTRONIC PARTS, semiconductors. kits. FREE FLYER. Large cat- Tron-X Manual, P.O. Box 38155, Hollywood, CA 90038. $5.95. alog $1.00 deposit. BIGELOW ELECTRONICS, Bluffton, Ohio 45817. JAPAN HONG KONG DIRECTORY. World products information. RADIO-T.V. Tubes-36C each. Send for free catalog. Cornell, $1.00 today. Sekai Shogyo Asnai, Hillyard, Washington 99207. 4213 University, San Diego, Calif. 92105.

NEW SEMICONDUCTOR LIGHT EMITTING DIODES -bright red lights replace light bulbs. Typical life 100 years. Operate at 1.65 DEALERS WANTED! volts, 50 milliamps. Order 2 for $2.98 NOW. Data sheet and in- CITIZENS BAND, AM, SSB, Two-way Radios & Acces- the structions included. Monsanto Company, Hobby Section, 10131 sories. USA and export models. We ship around Bubb Road, Cupertino, California 95014. world. Send letterhead -to: BAGGY'S RADIO CONVERT any television to sensitive, big -screen oscilloscope. P.O. Box 778, 6391 Westminster Ave., Only minor changes required. No electronic experience neces- Westminster, California 92683 sary. Illustrated plans, $2.00. Relco-A33, Box 10563, Houston, 714-894-3301 Texas 7701E.

117 FEBRUARY 1972 We can supply .Japanese re- 7475 Quad Bistable Silicon Power Rectifiers DECADE COUNTER KIT placement transistors, recti- Latch ..1.40 PRV IA 3A 304 12A Consisting of: fiers and SCR's in Quantity. 7476 Dual Mast -Slave 11( FF 100 .06 .09 .30 1 -Nixie tube 6 socket (8754) Phone or send us the part ...... 1.00 .50 1 7490 numbers o specifications 7490 Decade Counter ...1.50 200 .16 7492 Divide By Twelve ..1 85 .07 :35 .80 1-7475 VARIABLE CAPACITANCE 7481 16 bit read/write 400 .09 .20 .45 1.20 1-7441 DIODES memory 2 00 600 .11 .30 .70 1.50 709C OPER AMP $ .70 (Similar to 1N5463A) used to 7409 Hex Inverter 40 741 OPER. AMP. $1.00 tune VHF, color TV, & FM 7447 BCD to seven de- 800 .15 .40 .85 1.80 723 VOLTAGE broadcast sets coder/drivee ..2.00 1000 ..$1.00 74121 Monostabl multi- .20 .55 1(10 2.20 'REGULATOR 51.25 PROGRAMMABLE UJT's vibrator 90 Silicon Control 'Rectifiers Similar 013T, with NIXIE TUBES PRV 3A 7,8 20A 704 too 7S T R 1 A C 5 data Similar to Raytheon 50 .25 .28 .60 PRV IA IOA 15A 20A 8754. with socket & 100 .38 3.50 ER900 TRIGGER D I OD ES 100 .40 .70 1.00 1.20 data sheet $3.00 .30 .85 These bidirectional trigger di 200 200 .50 .60 1.10 8.50 odes one of the best and .70. 1.10 1.40 160 cheapest methods to trip Derr 300 .90 1.35 1.80 2.00 Terms: FOn Cambrid gt'. Mass. 300 .60 .68 1.30 SCR's and'triacs melt cheek or Money 'Order. .. .4/1 400 1.10 1.60 2.60 2.40 Wt 400 .70 .75 1.50 9.50 8 TTL IC SERIES (DIP) gib. are.500 ce[ipaekagedesy No ('.e. Ó. 500 .80 .85 1.70 1.50 2.00 2.20 2.80 7,441 BCD Decimal Minimum Ortler $3.00 ).'s. 600 .90 1.20 1.90 11.00 Decoder 1 75 Press Fit Rated companies 30 days net Send $.20 for our Latest catalog featuring Transistors and Rectifiers; 325 Elm St. Cambridge, Mass. ,SOLID .STATE SALES Post Office Box 74A Somerville, Mass. 02143 Tel. (617) 547-4005 CIRCLE NO. 39 ON READER SERVICE CARD

EUROPEAN and Japanese bargains catalogs. $1 each. Dee, P.O. SURPLUS regulated power supplies. 12 to 24 volt at 3 amps. Box 9308, North Hollywood, Calif. 91609. $8.00. Details and other items. Superior -Racine, Inc., 1006 State St., Racine, Wisconsin 53404. BURGLAR ALARM SYSTEMS. We manufacture intruder -fire detection systems, radar and perimeter types. Accessories available. PYROTECHNICAL chemicals, casings, tools, supplies, fuse, Free Literature. Inquiries for dealership and wholesale prices literature. Giant, illustrated catalogue/handbook includes must be on letterhead. U.S. and Canada only. Microtech Asso- formulas, instructions -500, with samples -$1.00. Westech, ciates,Inc., Box 10147, St. Petersburg, Florida 33733. Salt Lake City, 84108.

VHF ignition coil 60 times faster than conventional. Connects ". ISTENINkTO$JEJ LS1N YOUR(CAR! direct to any CD system. Molded epoxy $9.95. Perkins Electric, ra RKS with R' V CÁR-Potta lr or HOME RA- 1022 Newton, DIO! .lust PLUGS In -No wiring -3 minute Denver, Colorado 80204. hookup! Switch Instantly from regular to ALL POLICE -FIRE -EMERGENCY -COMMERCIAL - 2 METERS TAX I CABSTATE-CITY-GOV'T wayy Radio -Surplus, new, used, panel or portable. Send for list. calls in YOUR AREA. DUAL-HI-LOW Hanchett, Box 5577, Riverside, CA a MILLION Radio Cars/stations. USE 92507. Far tvhrt anytime -always works: ELIMINATE distributor points with magnetic SEND ONLY $2.00 1.2shs7 99 Sii;11;,! miIt.tstr"; pickup system using send 511.119 for ppd Del in USA. COMPLETE. ready to use with In- your C.D. ignition or our complete system. structions. One Year service Warranty -10 DAY MONEY BACK TRIAL Rugged and reliable, III retndl. AMAZING OFFER Rood Only by mail - uses standard inexpensive parts. SES-1 plans for use with your WESTERN RADIO Dept. BPE-2 KEARNEY, NEBR. 68847 C.D. $4.50. SES-2 plans our complete system $5.50. Both for $7.50. SES Enterprises, Box 607, Ferndale, Wash. 98248. CONSTRUCTION PLANS: Laser . . . $2.00. Investigation Aids - 2 -FM Microphone Transmitters . . . $1.00. FM Telephone Trans- HOBBYISTS! Logic IC project kits. Combination Lock, $5.95. mitter ... $2.00. Sound Telescope . $2.00. Space Monitor - Catalog free. John Huntley, 1351 Mahoney, Rodeo, Calif. 94572. Missile Tracker . $2.00. Free equipment and kit catalog. Howard, 20174 Ward, Detroit, Michigan 48235. GUARANTEED MONEYSAVER! "How to Use Bargain Transistors" explains how to build 100 projects with old, unmarked and CLEARANCE SALE rectifiers, transistors, 1000's other items. Cat- surplus semiconductors. 132 pages, illustrated. $3.00. alog 15C. General Sales Company, 254 Main, Clute, Texas 77531. Capstone Corp., 9 Danbury Rd., Wilton, Conn. 06897.

OVER 1,000 new electronic parts, list $240.00, yours $19.95. PSYCHEDELIC Equipment. Catalog/Handbook. Send 500. One Trip 28 Music pages $1.25. All postpaid. Hobbytronics, 921 East 19th, Beyond, P.O. Box 2043, Dearborn, Michigan 48123. San Angelo, Texas 76901. TREASURE! Patented home -built metal locator. Easy plans rushed FREE catalog, parts, circuit boards for POPULAR ELECTRONICS -$2.00. Inco-7R1, Box 5373, Station -F, Ottawa, Canada, K2C projects. PAIA ELECTRONICS, Box C14359, Oklahoma City, Ok. 311. 73114. SOCKETS Transistor and I.C. Send for catalog. Star Displays, DIAGRAMS -Radios $1.50, Television $3.00. Give make and mod- Inc., 1655 W. 11th Avenue, Eugene, Oregon 97402. el. Diagram Service, Box 1151PE, Manchester, Conn. 06042. BURGLAR and Fire Alarms from $31.95. We manufacture home 1972 ELECTRONICS Catalog McCord Electronics, Box 41Z, and commercial units -retail and wholesale (dealers wanted). Sylvania, Ohio 43650. Tri-Western Industries, Inc., P.O. Box 556, San Jose, Calif. 95106. NOW! Enjoy the great outdoors in comfort with your pocket size UNUSED Synchro Transmitter: 115/90V, 60 cycles AC. 201; Price electronic Skeeter Skat mosquito repeller. $9.95 postpaid USA. list. A. Chu, Box 86, Fort Lee, N.J. 07024. Satisfaction guaranteed. Detectron, Dept. G-2, P.O. Box 243, San Gabriel, Calif. 91778. FREE catalog new electronic devices! World's smallest trans- STEREO headphones individual volume controls, limited quantity mitter $19.95! Telephone Answerer $49.50! Telephone Recording Device $19.95! Lie Many available, $12.95 + $1.25 mailing and handling, N.C. residents Detector $19.95! more! Sonic Devices, add 3% sales tax. Neal's Enterprises, 2703 Belmar St., 69-29E Queens Blvd., New York 11377. Greensboro, N.C. 27407. TELEPHONE parts, resistors, capacitors. Brochure-100. Comet ELECTROENCEPHALOPHONE teaches alphawave control. J&J Enter- Communications, Dept -B, 639 50th Street, Brooklyn, New York prises, 24120-E 3rd West, Bothell, Wash. 98011. 11220.

TV TUNER REPAIRS -Complete Course Details, 12 Repair Tricks, INSTANT CIRCUITRY -apply on two enclosed PC boards, no liq- Many Plans, Two Lessons, all for $1. Refundable. Frank Bocek, uids. Price $3.00. Security Systems, P.O. Box 4754, Colorado Box 833, Redding, Calif. 96001. Springs, Colorado 80910.

RECONDITIONED Test Equipment. Reasonably priced, list avail- INTEGRATED CIRCUITS, 74N series, low, low, prices. Send for able. Walter, 2697 Nickel, San Pablo, CA. 94806. free list. B&A Supply, Box 24211, Fort Lauderdale, Florida 33307.

118 POPULAR ELECTRONICS Including Electronics World construction plans -alternator adapter -ultra -sensitive metal de- PHONE PATCH -EASY TO INSTALL tector -x-ray fluoroscope machine -silver recovery unit -coin A Phone Patch PIIP-I hooked up to your phone in cleaner/electroplater-chemical formulary (home products) conjunction with recorder will automatically boat - engage the ireordera upon tricking up your tele- radar unit -radar oven -infra -red viewing system -plans phone receiver. Your recorder is now ready to $5.00 each -Plus Many ord the entire conversation. Upon completion of More! -ask for our Free color catalog- the e call and replacement of the teletrltone receiver. Creative Products, 1551 East Loop 820, the recorder automatically shuts off and you have Department EB, Fort fin udio record of what has been said. Ideal for Worth, Texas 76112. confirming orders Or statements. Perfect for confirming messages taken try your answering service. NET: $19.95 ELECTRONIC HOBBYISTS and professional builders love TELECO. 1351 Pearl Street, Santa Monica, CA 90405 our 30 film resistors; 160 electrolytics and 1% micas. Great catalog 35C. Electrovalue-America, Box 276, Swarthmore, Pa. 19081. JOHNSON CB RADIOS. Low discount prices, prepaid shipping. COMPUTER MasterCharge. Free list. Hughes Electronics, Box 6487A, analyzes your car's economics. Write: DoubleM, Box Asheville, N.C. 28806. 491, Janesville, Wisconsin 53545.

SUPREME twenty different radio -television volumes, $50 value, only $19.95, postpaid. Supreme Publications, 1760 Balsam, PLANS AND KITS Highland Park, Illinois 60035. KITS -Color organs, synchronizers, strobes. TV REPAIRS costing you money? You need Dial -A-Fix! Odds are Workshop, Box 393Z, Bethpage, New York 11714. 4:1 you can repair your set in minutes. No experience necessary. Color or black & white. Send $2.98 for revolutionary diagnostic KITS AND EQUIPMENT-FM Wireless microphone transmitters, aid. KRK Enterprises, Dept A-2, Box 176, Ilion, New York 13357. FM Telephone transmitters, Infinity transmitters. Security Elec- tronics, P.O. Box 265, Huntington, W. Va. DESIGN and modify transistor circuits faster with new engi- 25707. neering layout form. Ideal for experimenters, engineers, service- ONE TUBE DX'ER Handbook -50C. Coil Winding -50C. Catalog. men, inventors. 10 forms, instructions Ph x 14" on eye -ease Laboratories, 745-L Cordone, Reno, Nevada 89502. paper. $3.00 postpaid. Incline Company, Windsor, Vermont 05089. BRAINWAVES-Build your own machine. We have plans, kits. Write: Extended Digital Concepts, Box 9161, Berkeley, Calif. PANORAMA of industrial and government electronic surplus in 94709. our monthly picture catalogs. Startronics, Box 17127, Portland, Oregon 97217. COMPUTER designed antenna plans. All -channel, UHF, VHF, one - channel, or any combination. Also television amplifier and quad- ELECTRONIC ORGAN KEYBOARDS, tone generator kits, etc. All rasonic hi-fi adaptor plans available. Build your own for a frac- types of components for building your own organ. Send 20C for tion of the manufactured cost. All plans $2.00 each. Satisfac- list. Devtronix Organ Products, 5872 Amapola Drive, San Jose, tion guaranteed! Computer Electronics, P.O. Box 2892, Champaign, Calif. 95129. Illinois 61820. COLOR TV psychedelic light show. Modify your set for RESISTORS -High quality, low prices, Free flyer. Kingtree, Box double 3092, Columbus, Ohio 53210. entertainment. Complete plans, $5.00. Send make, model. Audio Research Co., 9364A Jamacha Rd., Spring Valley, CA 92077. FREQUENCY Counter components SN 7441N/$1.70, SN 7475/ $1.40, SN 7490/$1.40, Amperex neon readout tube $3.00, Set COMPUTER BOARD $7.00. Free flyer. Davek, P.O. Box 104, Vestal, N.Y. 13850. SPECIALS INTEGRATED circuits, factory fresh at surplus prices. Displays and electronic experimenters project books. Marco Enterprises, POD 216, Dayton, Ohio 45401.

OSCILLOSCOPES USM 81, like Tektronix 535, D.C. to 15 MHz, with dual trace plug-in (other plug-in's available) $325. Testron- ics of Texas, 609 Riverside Drive, Fort Worth, Texas 76111. Day (817) 624-4511, Nite 332-4881. Open 5:00 P.M. till 10:00 P.M. Honeywell Computer boards, 41/2"x12". Tran- sistors, diodes, zeners, capacitors, precision INEXPENSIVE Antenna, amplifier, and quadrasonic equipment. resistors, heat sink, trimmers etc. 2 Different See Plans & Kits. boards $1.00. 3 lb. Stock No. F9082 DELTA Capacitive Discharge Ignitions. Free literature. Dealer inquiries invited. Southland Communications, Box 3591, Baytown, /1#4#30''...14 Texas 77520. )'.;33 . .1.. ryÍi'V4kif4n1 BATTERIES six used rechargeable 11/2V $3.00. Trowbridge, P.O. Box 418, Oaklawn, Ill. 60453. 10, 49".q BURGLAR Alarm Systems equipment, dealers and private. Write: United Security, Box 2428, Dublin, Calif. 94566.

CAR AIR Purifier. Cleans smog particles out of Air. Amazing, Honeywell Boards 51,á" x 6". Loaded with late no. proven, electrostatic principle. Makes driving a pleasure. Kits or transistors. diodes, resistors and capacitors. 2 differ- plans. Catalog 35C. CSDC, 15446 Sherman Way, Van Nuys, Cal. ent boards. $1.25. 2 lb. Stock No. F9094 91406. COMPUTER GRADE CAPACITORS (BRAND NEW) ANTIGRAVITY device. Brochure 350. AGD, Box 16126-E, Wichita, 40,000 mf.i. 10 volts 1.25 ea. 6/7.00 Stk. No. F202í, Kansas 67216. 70,000 mfd. 10 volts 1.75 ea. 6/0.00 Stk. No. F2118 6000 mfd. 55 volts 1.50 ea. 7/9.00 Stk. No. F2117 3,750 mfd. 75 volts 1.75 ea. 6/9.00 WE SELL Construction Plans, Kits and Wired Units -120 volts Stk. No. F2116 at 3,000 watts of electricity from ANY alternated vehicle using MINIMUM ORDER $3.00 Lots of other our special adapter! Operate electric drills, lights, items -seed for free flier; all mer- heaters, port- chandise fully guaranteed. saws, AD -DC TV's Please include postage; able and many more AC devices! Arc weld 1/4" excess will be refunded. steel plates! Fully charge 6,12,24 volt batteries in minutes! Will not harm alternator! Installation takes only ten minutes! Send DELTA only $9.45 for complete kit, $11.45 for assembled unit or $14.95 ELECTRONICS CO. BOX 1, LYNN, with voltage indicating light, comes on when alternator is pro- MASSACHUSETTS 01903 ducing 120 volts! Plus Many Other Products Just as Useful! - CIRCLE NO. 12 ON READER SERVICE CARD FEBRUARY 1972 119 RECEIVING & INDUSTRIAL TUBES, TRANSISTORS. All Brands- Biggest Discounts. Technicians, Hobbyists, Experimenters -Re- FIDELITY Turn- HIGH quest FREE Giant Catalog and SAVE! 2ALYTRON, 469 Jericho pike, Mineola, N.Y. 11501. OVER 20 YEARS Successful Discounting of Audio Equipment -receiving tubes, foreign - insures best value and service. Specialize in Stereo Components, SAVE money on parts and transmitting Refunded first order. Tape Recorders, Cassettes, Magnetic Cartridges, Sleep Learn domestic. Send 250 for giant catalog. Newark, N.J. 07105. Equipment, etc. Low Quotes, Free Catalog. DRESSNER 1523PE United Radio Company, 56-P Ferry Street, Jericho Turnpike, New Hyde Park, New York 11040. TUBES "Oldies", latest. Lists free. Steinmetz, 7519 Maplewood, 46324. DIAMOND NEEDLES and Stereo Cartridges at Discount prices for Hammond, Indiana Stanton, Empire, Grado and ADC. Send for free Shure, Pickering, ELECTRONIC TUBES, Semiconductors, Equipment, Telephones, All brand new and factory sealed. LYLE catalog. merchandise Public Address, Intercoms, CB, Walkie -Talkies, etc. Quality Mer- P.O. Box 69, Kensington Station, Brooklyn, CARTRIDGES, Dept. P, chandise Only! Serving Engineers, Purchasing Agents, TV/Hi-Fi New York 11218. Servicemen and Hams for 28 years, Domestic and Exonrt. Write for Catalog or call (212) 925-7000. BARRY ELECTRONICS, 512 HEGEMAN "OMNI-DIRECTIONAL" SPEAKERS $100. Creighton Broadway, New York, N. Y. 10012. Audio Labs, Haven PI., Linden, N.J. 07036. TUBES receiving, factory boxed, low prices, free price list. Transleteronic, Inc., 1306 40th Street, Brooklyn, N.Y. 11218A, McGEE RADIO COMPANY Telephone: 212-633-2800. World's Best Selection of Speakers Almost Every Size From 1'/2 to 18" TAPE AND RECORDERS WOOFERS - TWEETERS - CROSSOVERS Gold MANY HIGH FIDELITY KITS. STEREO TAPE RENTAL for particular people. Free catalog. Coast Tape Library, Box 2262, Palm Village Station, Hialeah, Fla. McGee's 176 Páge Catalog 33012. Sent Free Upon Request STEREO TAPE TRANSPORT -7" reel -2 speeds -pause control - NORELCO HI -Fl SPEAKERS made for famous manufacturer -50 to 15,000 Hz -with rec/play and erase heads, without case. Send m.o, or check for $19.50 An Added Full Line of Norelco Hi -Fi Speakers to Alsheimer Audio Electronics, 218 Columbia St., Utica, N.Y. For The System Builder 13502. $2.50 for prepaid shipping and insurance. at McGEERADIO COMPANY, BUY Irish Tape Open Reel & Cassettes & 8 -Track Blanks 71, 1901 McGee Street PE, Discount Prices. Write: Direct Mail Cassette Corp., Box Plainview, N.Y. 11803. Kansas City, Missouri 64108 RECORDING TAPE made by top American manufacturer, guaran- HI-FI system designed especially for you. Professional help in teed not "seconds" or "white box"; 2400' mylar, $2.29: 1800' selecting your components. For information write: Donald mylar $1.69; 1200' acetate $.79. Send for information and quan- Daugherty, 5754 Backlick, Springfield, Va. 22150. tity pricing. Alsheimer Audio Electronics, 218 Columbia Street, Utica, New York 13502. STEREO Components at lowest prices. Send for free catalog. Carston, Box 1094-A, Danbury, Conn. 06810. low OLD Radio Programs on cassettes or reels. Nigh quality, prices, thousands to choose from, professional equipment. catalog 50C. Remember Radio Inc., Box 2513, Norman, Okla. WANTED 73069.

Radio Vault, QUICKSILVER, Platinum, Silver, Gold, Ores Analyzed. Free Circu- OLD Radio Programs. Catalog $1.00. (Refundable). lar. Mercury Terminal, Norwood, Mass. 02062. Box 9032, Wyoming, Michigan 49509. Mercury, CASH immediately for old Gold, Silver, Platinum, VIDEO Tape r/ºin. wide from the number one manufacturer. Re- Watches, Diamonds. Free information. Rose Industries, 29-PB conditioned and guaranteed. 30 minutes $5.50, 60 minutes $9.25 East Madison, Chicago III. 60602. plus shipping. EHI, P.O. Box 20643, San Diego, Calif. 92120.

CASH for Electronic Tubes, Semi -Conductors, Equip- QUICK ... "OPEN -REEL" prerecorded tapes-all labels -2,500 titles -save Transmitters, Scopes, Vacuum Variables etc.) ment (Receivers, 30% -catalog $1.00 (refundable) Stereo-Parti, 55 St. James Send Lists now! Write: Barry Electronics, 512 Broadway, New Drive, Santa Rosa, Calif. 95401. York, NY 10012. (212) 925-7000.

x 1700 feet. Used. On computer B&K model 445 CRT Tester and rejuvenator. Robert Bezak, 303 VIDEO TAPE, 1 inch x 1 mil. 656, Martinsburg, W. Va. Mapeat Lane, New Castle, Penna. 16101. reels. $12.00 each. LAHILL, P.O. Box 25401. SUPPLIES AND ELECTRICAL SCOTCH TAPE #150, 1800 foot, 7" reel, polyester, $1.95, post- EQUIPMENT paid, $22.50 dozen (48 @ $1.75). Recorders, cassettes, open reel music tapes (100-page discount catalog 250, Saxitone Tape PLATING Equipment, Portable Platers, Supplies and "Know - Sales, 1776 Columbia Road, Washington, D.C. 20009. How." Build your own tanks for nickel, chrome, etc. Easy -to - sizes. Schematics, install PVC liners. Rectifier components -all RENT 4 -Track open reel tapes -all major labels -3,000 different for plating. Parts lists, formulas, operating instructions all -free brochure. Stereo-Parti, 55 St. James Drive, Santa Rosa, you 25%-75%. Some good units for sale. Guaranteed to save Ca. 95401. Write for details. Platers Service Company, 1511 -PE Esperanza, Los Angeles, Calif. 90023. SOUND TRACKS for slides made easy. Send 25C for "Slides with Sound." Synchronizer, Box 12375, North Kansas City, Missouri TUBES 64116. MEMOREX recording tape, audio & video lowest prices, write for Systems Co., Box 1181, Melrose Park, RADIO & T.V. Tubes -36C each. Send for free Catalog. Cornell, free information. Bergetz 4213 University, San Diego, Calif. 92105. III. 60161. Electronics World 120 POPULAR ELECTRONICS Including RECORDING? Dubbing? Editing? Use the "Dubie" control. Inte- grate two or more recorders into your music system. End tan- FAIRCHILD'S gled cables, ruined tapes. Brochure F-5, Dubie Co., 1509 POPULAR "IC" Oklahoma, Norman, Okla. 73069. TWINS -. RTL914' & RTL923

o RTL-914 Dual 2 Input Gate Complete catalog! p RTL-923 .1K Flip Flop "VISIBLE" LIGHT 6,000 EMITTING DIODES STEREO Micro mini, axial lead $ .88 2 for $1.45 Jumbo, TO -18, 2 leads red 1.00 2 for 1.75 TAPES BRAND NEW! LINEAR IC AMPS Type Description Sale Sale 703 RF-IF, Pop Rock Jazz Folk Country 14 hookups, TO -5 . . $1.19 3 for $3.00 and Western Classical Complete 709C Operational Amp .... .59 2 for 1.00 new A 710C Differential Amp .59 2 for entertainment guide. must for o 711C Memory, 1.00 every owner of an open reel, 8 -track Sense, Amp... .59 2 for 1.00 723A Voltage Regulator (DIP) . cartridge, or cassette 1.49 3 for 3.75 player/recorder. TVR-2000 Hi -power 723 (DIP) 1.59 3 for 3.95 Send 50f in coin, check, or money 13741C Freq. Comp. 709*** .95 3 for 2.50 order to Ampex, 2201 Lunt, Elk Grove 748C Freq. Adjustable 741*'. .95 3 for 709-709 Dual 2.50 Village, Ill. 60007. ATTN: Dept. 144 709's (DIP) ... 1.49 3 for 4.00 " 741-741 Dual 741's (DIP) ... 1.98 3 for 5.50

State 1st, 1 [ AMPEX] 2nd choice, Dal In Line, TO -5. STEREO TARES TELEDYNE -FAIRCHILD 16 -TRANSISTOR STEREO PRE -AMP "BC" Only $2.49 LOW REPAIRS AND NOISE! Type 739. 8 transistor per channel. For 3 SERVICES , magnetic stereo phone and tape recording devices. 508 input imp., 20,000 input gain. Provides RIAA 101 band shape. Supply volts: 6 to 18V. Dual In Line $6. TV Tuners rebuilt and aligned per manufacturers specification. package. Specs, diagrams. Only $9.50. Any make UHF or VHF Ninety day written guarantee. TTL "IC DIP" PRICE SLASHES! Ship complete with tubes or write for free mailing kit and dealer m brochure. JW Electronics, Box 51C, Bloomington, Indiana 47401. Factory Marked! Factory Testedl °Factory Guaranteed! Type Function Sale SN7400N Quad 2 input NAND gate $ .39 DO-IT-YOURSELF SN7401N SN7400 with open collect .39 5N7402N Quad 2 input NOR gate .39 SN7404N Hex Inverter .39 5N7410N Triple 3 input NAND gate .39 PROFESSIONAL ELECTRONICS PROJECTS -$1.00 up. Catalog 250. SN7420N Dual 4 input NAND gate .39 PARKS, Box 25665A, Seattle, Wash. 98125. SN7430N 8 Input NAND gate .39 o SN7440N Dual 4 input NAND buffer .39 5N7441N BCD -to -Decimal driver 1.50 SN7446N BCD -to -7 seg. dec./driver 2.25 PERSONALS rT SN7447N BCD -to-, . dec./driver 2.25 U sr17473N Dual 1.1( Master slave flip-flop .88 o SN7474N Dual D triggered flip flop .69 o SN7475N Quad blstahle latch 1.50 INVESTIGATORS, latest Electronics Aids. Free Literature. Clifton, SN7476N SN7473, with preset -n -clear .88 SN7481N 16 11500-K NW Ave., -bit memory (scratch pad) . . 1.50 7th Miami, Florida 33168. 5N7483N 4 -bit bleary full adder 2.25 (l SN7490N Decade counter 1.50 COMPUTER Dating Explained. Free information, House of Hoke, Box 101 -PE, Sebring, Florida 33870. 4,000 BIT MAKE FRIENDS WORLDWIDE through international correspon- E. MEMORY dence. > Illustrated brochure free. Hermes, Berlin 11, Germany. j. ilwwrr.owr $9.95 .itt;;sc:.ki :_- horn IBM Computers, ::luli:r:u.n: Guaranteed/ INSTRUCTION Rlh},mG .fRhnr_.,,i.. W/Spec Sheets "PIK-A-PAK" OF FACTORY IC KITS LEARN ELECTRONIC ORGAN SERVICING at home all makes includ- Front Factory To You! No Test! With Diagrams! ing transistor. Experimental kit -trouble -shooting. Accredited 24-709, 710, 711, NHSC, Free Booklet. NILES 723. 741 asst. cases ... $2.98 BRYANT SCHOOL, 3631 Stockton, 24-7400 Serles, Dual in line. asst. 1.98 Dept. A. Sacramento, Calif. 95820. 24-Linear & 7400 Series, asst, cases 1.98

LEARN WHILE ASLEEP, Hypnotize! Strange catalog free. Auto- COUNTING SYSTEM WESTINGHOUSE suggestion, Box 24-ZD, Olympia, Washington 98501. AM.FM ° .1 -pc. 41;;; kit SOLID F. C. C. 1st phone license training in 5 weeks. R.E.I.'s $6 99 STATE intensive training produces outstanding results. For information 3 for TUNER and free brochure call toll free: 1-800-237-2251, or write home $18 office, Radio Engineering Incorporated Schools. 1336 Main Includes S\7490 dec Street, Sarasota, Florida 33577. Florida residents call (813) ' silt counter, 557476 latch, 955-6922. 557a41 BCD decoder -driver. and a \isie' tube that indi- HIGHLY effective home study courses in cates0 to 9, instruc- Electronics Engineering tions. Technology and Electronics Engineering Mathematics. Earn your Degree. Write for Free Descriptive Literature. Cook's Institute of Terms: add postage. Rated: net 30, cad's 25 fí . C4l Electronics Engineering, (Dept. 15), P.O. Box 10634, Jackson, Phone Orders: Wakefield, Mass. (617) 2.15-31129 Miss. 39209. (Established 1945). Retail: 211 Albion St., Wakefield, Mass. (0e P.O. BOX 942 E SC ASSOCIATE DEGREE IN ELECTRONICS through correspondence POLY PAKS Lynnfield Mass. 01940 instruction. G.I. Bill approved. Free catalog. Grantham, 1509 N. Western, Hollywood, California 90027. CIRCLE NO. 34 ON READER SERVICE CARD

FEBRUARY 1972 121 LIBERTY PAYS %- MORE! INVENTIONS WANTED WILL BUY FOR CASH INVENTIONS wanted. Patented; unpatented. Global Marketing ALL TYPES: Service, 2420-P 77th, Oakland, Calif. 94605. * ELECTRON TUBES * SEMICONDUCTORS INVENTORS! Don't sell your invention, patented or unpatented, * TEST EQUIPMENT until you receive our offer. Eagle Development Company, Dept. * Military Electronic Equipment 9, 79 Wall Street, N.Y., N.Y. 10005. WIRE-WRITE-PHONE COLLECT PATENT Searches including Maximum speed, full airmail report We pay freight on all purchases-on above only! and closest patent copies, $6.00. Quality searches expertly ad- ministered. Complete secrecy guaranteed. Free Invention Pro- LIBERTY OFFERS MORE! tection forms and "Patent Information," Write Dept. 9, Washing- PRESTEL FIELD STRENGTH METER ton Patent Office Search Bureau, 734 15th St. N.W., Washington, D.C. 20005. (Model 6T4G) New Products." Only FREE "Directory of 500 Corporations Seeking For information regarding development, sale, licensing of your $142.00 patented/unpatented invention. Write: Raymond Lee Organization, F, 230-GR Park Avenue, New York City 10017. F.U.B. New York Model MCI6 INVENTORS: Protect your ideas! Free "Recommended Proce- Larger loud speaking dure". Washington Inventors Service, 422T Washington Building, model -2.5 microvolt Washington, D.C. 20005. only 3317.00 F.O.B. New York FREE PAMPHLET: "Tips on Safeguarding Your Invention." Write: * Never Anything Like It! United States Inventors Service Company, 501-H Thirteenth * 1 -Man Can Do A Better lob than Street N.W., Washington, D.C. 20004. 3 in the Same Time! * A Gold -Mine for Antenna Installers! Calibrated from 40 to 230, and 470 to 860 in 4 Bands GOVERNMENT SURPLUS Megahertz, from 10 to 50,000 Microvolts. Nothing makes it easier to properly and speedily find the correct place to install TV, FM and Communication Antennas. You can measure Where to Buy in Your Area. Send and hear the signals with this 41/2 volt battery economically GOVERNMENT Surplus. How and powered unit. $1.00. Surplus Information, Headquarters Bldg., Box 30177 -PE, Washington, D.C. 20014. LIBERTY ELECTRONICS, Inc. 548 Broadway, New York, New York 10012 ELECTRONIC Equipment and Parts. Big 36 page Free Catalog. Phone (212) 925-6000 Send for your copy today! Fair Radio Sales, Box 1105-P, Lima, Ohio 45802. CIRCLE NO. 28 ON READER SERVICE CARD

JEEPS Typically from $53.90. . Trucks from $78.40 . F.C.C. TYPE EXAM . Guaranteed to prepare you for F.C.C. Boats, Typewriters, Knives, Airplanes, Clothing, Multimeters, 3rd, 2nd, and 1st phone exams. 3rd class, $7.00; 2nd class, Oscilloscopes, Transceivers, Photographic, Electronics Equip- $12.00; 1st class, $16.00; complete package, $25.00. Research ment. Wide variety, condition. 100,000 Bid Bargains direct Company, 3206 Bailey Street, Sarasota, Florida 33580. from government nationwide. Complete sales directory and surplus categories catalog $1.00 (Deductible on orders from FCC 1972, First and Second tests, $8.95. Electronic Tutoring, Box 820-1, Box 24190, Cleveland, Ohio 44124. separate included catalog). Surplus Service, Holland, Michigan 49423.

EXAM GOVERNMENT SURPLUS. Complete sales directory $1.00. Surplus F,C.C: Publications, Box 26062Z, Los Angeles, Calif. 90026. . MANUAL the Original Test -answers exam manual that prepares you at home for FCC First and Second class licenses. Includes Up - BOOKS Dated miltiple choice tests and key Cnm Schematic diagrams. PLUS - "Self -Study ur Ability Test." -- ONLY: $9.95 Postpaid' h erll1 FREE catalog aviation/electronic/space books. Aero Publishers, COMMAND PRODUCTIONS P.O. BOX 26348-P 329PE Aviation Road, Fallbrook, California 92028. RIDIO.IiGINNRING O0111010 SAN. FRANCISCO,, CALIF. 94126' FREE book prophet Elijah coming before Christ. Wonderful bible CATHODIC Protection instructions $1.00, F.F. Knapp, P.O. Box evidence. Megiddo Mission, Dept. 64, 481 Thurston Rd., Roches- 854, Scottsdale, Arizona 85252. ter, N.Y. 14619.

ELECTRO.OPTICS. The now technology. Free brochure. Epi, Education Dept., Box 413 Mountain View, Calif. 94040. MAGAZINES SPECIALIZED CORRESPONDENCE COURSES: Integrated Circuit Engineering $49.50, Telephone Engineering $39.50, Detective JAPAN PUBLICATIONS GUIDE Business, pleasure, education. Electronics $22.50, Anti -Detective Electronics $27.50. Don $8.00. INTERCONTINENTAL, CPO 1717, Tokyo 100-91. Britton Enterprises, 6200 Wilshire Blvd., Los Angeles, Calif 90048.

YOU CAN understand ELECTRONICS theory and operation-with HYPNOTISM unique self -study texts. One -idea -per -page method, 1,000 color illustrations insure comprehension. Complete 7 -volume course, $14.95. (Or try introductory volume-only $3.00.) Money -Back "MALE -FEMALE Hypnotism" Exposed, Explained! "Secret Method" Guarantee. Unitext, Box 188-A, Glen Ridge, N.1. 07028. -They Never Know! $2, Rushed. Guaranteed! Isabella Hall, Sil- ver Springs, Florida 32688. DRAFTING, Blueprint Reading, (electrical, mechanical, architec- tural). Home courses, $25.00. Send $2.00 first lesson. Prior, SLEEP learning. Hypnotic method. 92% effective. Details free. Inc., 23-09 169th Street, Whitestone, N.Y. 11357. ASR Foundation, Box 7545PL, Fort Lauderdale, Florida 33304.

122 POPULAR ELECTRONICS Including Electronics World IMPOSSIBLE? BARGAINS IN SURPLUS ELECTRONICS AND OPTICS

SURPLUS TTL INTEGRATED FEATURE ITEM! CIRCUITS, BRAND NEW IN ORIGINAL Texas Instruments MANUFACTURERS CARTONS TMS-1802 "Calculator a Chip". This is B & F has one of the worlds largest g-1969 on inventories of surplus integrated tomorrows technology today, and at a fraction circuits. All are new, meeting all manufacturers original - of list price. This calculator logic unit - specifications, and in factory ' a 3,520 bit low prices should r.1970 - consists of packaging. The program speak for themselves. Manufactured read-only memory, a 182 bit by Texas Instruments, National, - _ random memory, a Signetics or Philco, no choice. All - °-1 ° . _ 1971decimal- arithmetic logic packages are 14/16 lead silicone Dual In-Line Pak. =dr - - _ 5 - unit, plus timing, control, NEW LOWER PRICES! and output decoders. The Thi' uu.ew^n " dn.kea'"""" me ""'"'. "' c^mpo ITEMS AT In 1969 features are: eight , ury for implementation of an 8dirit, ^iimr. 95Q e digits four opera - 401 $1.75 theerro,l' required 0,/ensof blyd,r d,.,k, lb1970 de v 7400 7409 7450 7406 7470 7413 7480 74141 root t ion s three r e g i 6- imrlutiented on a 9nr1, 1105/ SruJr. 7401 7410 7451 7407 7472 7442 7483 74151 9e it naa leeit ters floating or fixed 7402 7411 7453 7416 7473 7443 7490 point decimal constant or chain operations automatic 7403 7420 7454 7417 7474 7444 7494 roundoff leading zero suppression internal keyboard 7404 7421 7460 7426 7486 7475 7495 encoding and debouncing decoded display outputs single 7405 7430 7437 74121 7476 7496 phase clock operations 28 pin DIP package internal power 7408 7440 7438 74122 7477 74107 on clear.

S2.00 S2.50 S2.75 S3.75 S5.75 S9_75 Every TM -1802 is a brand new Texas Instruments factory 7448 7445 7441 74150 7485 74166 7489 packaged, fully guaranteed unit. The only devices required to 7491 7447 7491 74152 74182 74198 74170 build a calculator are a battery, clock generator, keyboard, 7492 7448 74123 74153 74199 74181 display drivers, and eight digits of display, all available from B & 7493 7483 74154 2501 F. Full schematics, specifications and instructions from T.I. are 74180 74145 74192 included. 74194 74193 Texas Instruement TMS 1802 Calculator Chip . . . . $29.00 HOT NEW INTEGRATED CIRCUIT ITEMS! Texas Instruments keyboard $19.00

T.1. SN25391, SN26392 Drivers, 4 required . . .1 for S 3.00 7413 Dual NAND Schmidt Trigger S 1.75 All parts for clock generator S 4.75 7485 Magnitude Comparator 3.75 Readouts, eight required 1 for S 3.50 Dual One W/clear 2.75 74123 Shot O Complete package, except battery $88.00 74153 Dual 4 Line to 1 Data Selector/multiplexer 3.75 7489 64 Bit Random Access Memory 9.75 74170 4 x 4 Register File 9.75 74181 Arithmetic Logic Unit 9.75 .. SPECIAL! SHARP 74182 Look Ahead Carry Generator 3.75 MODEL EL8A CAL- MOS Memory 9.75 2501 256 Bit Random Access CULATOR 74166 Parallel In Series Out Synch Shift Reg 5.75 -9 74198 8 Bit Shift Reg., Shift Right/left 5.75 The response to last months 74199 Same as 74198 5.75 l 234-5 s 7. offer of the Sharp QT -8 2513 MOS 64 x 7 x 5 ASCI Character Generator - generates 64 .. .'i. calculator was overwhelm- alpha -numeric characters on a 5 x 7 matrix of lamps (or on ing, and within a short a CRT) $25.00 period of time we ex- stock so 20% discount on all orders for 100 or more integrated circuits. All hausted their entire that this model is no longer with FREE mail over We /.C.'s postpaid, air on orders $50.00. available. Because of this strive to ship I.C.'s by return mail. Free data sheets on all items. unprecedented response, Sharp has offered B & F a special quantity purchase SANKO AUDIO AMPLIFIERS on the model EL8A, which is. the new pocket size a pur- We have made fortunate version of the QT8. We can chase of Audio Amplifier Sanko offer this model at only a 11 you Hybrid Modules. With these few dollars more than tile 1¡t Kon can build your own audio amp- QT8, a remarkable buy at only S192.50. ifiers at less than the price of SI-1025A I Don't forget, you can charge this, as well as other items to 111 discrete components. Just add a Mastercharge or BankAmericard. Fully guaranteed by Sharp !MOW POWER IC power supply, and a chassis to and B & F. act as a heat sink. Brand new a model EL8A $192.50 units, in original boxes, Sharp electronic calculator, guaranteed by B and F, Sanko

. '.v and the Sanko U.S. distributor. - Available in three sizes: 10 watts 0 80 PAGE CATALOG - Free with any order or send $0.25 RMS (20 watts music power), 25 watts RMS (50 watts M.P.) and 50 watts RMS (100 watts M,P.) per channel. 20 page manu lecturers instruction book included. Sanko amplifiers have proved ALL ITEMS POSTAGE PAID IN THE U.S.A. so simple and reliable, that they are being used for industrial applications, such as servo amplifiers and wide band laboratory Charges Welcoml: BankAmericerd - Masrercharge - $10.00 min. amplifiers. 0 10 Watt RMS Amplifier $ 4.75 B. & F. ENTERPRISES 25 Watt RMS Amplifier $14.75 Phone (617) 532.2323 50 Watt RMS Amplifier $22.50 P.O. Box 44, Hathorne, Massachusetts 01937 CIRCLE NO. 5 ON READER SERVICE CARD FEBRUARY 1972 123 GREGORY ELECTRONICS Reconditioned 8 Used PRO SPORTS ACTION FILMS FM 2 -WAY RADIO SAVINGS Partial List-Send for New Catalog SAVE -A -DOLLAR on every print you buy-February Special! '71 Indy, NFL, NHL, NBA, or '70 World Series. On 200, reels. Regu- GENERAL ELECTRIC larly $14.95 each color; $7.95 each B&W; Super 8/Reg. 8. SPORTLITE, Elec. Dept., 20 N. Wacker Dr., Chicago 60606. VOICE COMMANDER III FULLY SOLID STATE FM RECORDS Transmitter-Receiver POPULAR organ albums factory direct. Concert Recordings, Lyn- 132 to 172 MHz wood, Calif. 90262.

1 WATT OUTPUT CHAPEL Records Club-Free catalog. 1000-B Richmond, China Lake, Calif. 93555. 1/2 MICRO -VOLT SENSITIVITY W79 ORGAN albums. New and old releases. Catalog. Doric Records, Size: 9.5" x 5.3" x 1.7" P.O. Box 605, Alamo, Calif. 94507.

High performance, completely self- contained two-way FM radio. Com- STAMPS 1ñ pact, lightweight, easily operated YOURS FREE! 88 DIFFERENT COUNTRIES!! Incredible collection and hand -carried. Housed in high - Includes recharga- of genuine postage stamps-from Afghanistan to Zambia! Own impact 2 -section case. All external ble nickel cadmium battery pack and valuable stamps nearly 100 years old, moon stamps, etc. Also, hardware polished stainless steel. charger. (Crystals & exciting stamps on approval, returnable without purchases, tuning, add $50.) cancel service anytime. But this Valuable Collection plus Big Proper chargers available separately. Illustrated Catalog are yours to keep - FREE! Send 10C for $15. each. $148. mailing. H.E. Harris, Dept. SS -25, Boston, Mass. 02117. Lots of 5 More than 15,000 units in stock ... less 10% ..$133.20 WOW! 110 All Different Germany 10C. Commemoratives, Air- Lots of 10 mails, High Values, Big Catalog, bargain lists. Also, fine stamps send for new 1972 catalog. less 15% ..$125.80 from our approval service, which you may return without purchases and cancel service at any time. Jamestown Stamp, Dept. GREGORY ELECTRONICS CORP. A22EG, Jamestown, N.Y. 14701. 749-P Rt. 46, Saddle Brook, N.J. 07662 FREE! thousands of +- - Plums; (201) 489.9000 Big Bargain Catalog-New Edition listing packets, albums, ac- CIRCLE NO. 23 ON READER SERVICE CARD bargains including U.S. & B.N.A. stamps, cessories and supplies. Also, find stamps from our approval service which you may return without purchases and cancel AUTHORS' SERVICES service at any time. Jamestown Stamp, Dept. E22EG, Jamestown, N.Y. 14701.

AUTHORS WANTED BY RUBBER STAMPS

NEW YORK PUBLISHER RUBBER Address Stamps $2.00. Signature $3.50. Free Catalog. Leading book publisher seeks manuscripts of all Jackson's, Box 443-G, Franklin Park, Illinois 60131. types: fiction, non-fiction, poetry, scholarly and juvenile works, etc. New authors welcomed. For complete information, send for free booklet P-56. Vantage Press, 516 W. 34 St., New York 10001 EMPLOYMENT INFORMATION

EXCITING Overseas jobs. Directory $1.00. Research Associates, MUSIC Box 942-E, Belmont, California 94002.

ELECTRONICS/AVIONICS Employment Opportunities. Report on jobs now open. FREE details. Aviation Employment Information SONGS - POEMS Service, Dept. EW, Box 240, Northport, N.Y. 11768. Wanted for publishing and recording consideration. BUSINESS OPPORTUNITIES Accepted songs will be published & recorded at our expense for information write to I MADE $40,000.00 Year by Mailorder! Helped others make money! Start with $10.00-Free Proof. Torrey, Box 318-N, Ypsi- Talent, 17 -PE Longwood Rd.; Quincy, Ma. 02169 lanti, Michigan 48197.

$200.00 DAILY In Your Mailbox! Your opportunity to do what POEMS & LYRICS OF RELIGIOUS. REVERANT & mail-order experts do. Free details. Associates, Box 136.1, Hol- NATURE WANTED FOR IMMEDIATE INSPIRED land, Michigan 49423. RECORDING. WE ARE ONLY INTERESTED IN SONGS OF HOPE. GOD'S LOVE, THE COMFORT START small, highly profitable electronic production in your OF HIS WORDS AND WISDOM. SEND TO: basement. Investment, knowledge unnecessary. Postcard brings CATHEDRAL RECORDING CO. facts. Barta-PEL, Box 248, Walnut Creek, California 94597. Valuable lists, T11`'' P.O. BOX 78, STUDIO PE MAILORDER MONEYMAKING KIT. Home Business. concrete information, detailed steps. Capital unnecessary. Free NO. WEYMOUTH, MASS. 02191 details, pictures. Prudential, Box 327 -PE -2, Boston 02199.

124 POPULAR ELECTRONICS Including Electronics World FREE CATALOGS. Repair air conditioning, refrigeration. Tools, supplies, full instructions. Doolin, 2016 Canton, Dallas, Texas 75201, IÁEXPENSIVE, Home-Auto Fire, Burglar Alarms, Extinguishers. POPULAR ELECTRONICS 20Ó% Profits. Nation's Watchdog, Williamsburg, Ohio 45176. Including Electronics World PIANO TUNING learned quickly at home. Tremendous field! Musi- cal knowledge unnecessary, GI Approved- Information Free. FEBRUARY 1972 Empire School, Box 327, Miami Florida 33145. ASK for money. Never repay. How? $print, Upper Main Street, ADVERTISERS INDEX Dept. EW, Farmington, Maine 04938. READER EARN high profits selling shoplifting/robbery/burglary protection. SERVICE NO. ADVERTISER PAGE NO. National, Box 212 -PE, Stoneham, Massachusetts 02180. I Acoustic Research, Inc. 103 2 Allied Radio Shack 85 BIG EARNINGS selling Hertel Bibles. New 3 -dimension cover, finest reference edition sells fast. Demonstrator furnished. Big 3 Allied Radio Shack 97 commissions. International Book, Dept. PE, Box 118, Wichita, 4 Avanti Research & Development, Inc. 114 Kansas 67201. 5 B. & F. Enterprises 123 G B& K Division, Dynascan Corporation 107 MAILORDER MILLIONAIRE helps beginners make $500 weekly. 7 British Industries-Garrard II Free report reveals secret plan! Executive (1K2), 333 North Michigan, Chicago 60601. CREI, A Division of the McGraw- HIII Continuing Education Company 72, 73, 74, 75 MAILORDER-How to prepare your own catalog for pennies. Free 8 Center for Technical Development Inc., The 16 catalog! Obie-BGA, New York Brooklyn, 11219. 9 Cleveland Institute of Electronics 90, 91, 92, 93 10 Cobra Communications, Dynascan Corporation 15 II Crystek 113 TREASURE FINDERS 12 Delta Electronics Co. 119

14 Delta Products Inc. 17 15 Drake Company, R.L. 79 TREASURE FINDER locates buried gold, silver, coins, treasures. 16 EICO 106 5 powerful models. $19.95 up. Free catalog. Relco-A33, Box 10839, Houston, Texas 77018. 17 EICO 65 18 Edmund Scientific Co. 126 FREE: letco Electronics 24 -page Treasure Finder Catalog. 13 Electro -Voice. Inc. FOURTH COVER Find Gold, Silver, Coins, Metals, Minerals, relics. Jetco, 19 Electronics and Control Engineers' Book Club 7 Dept. PEC, 3933 Barranca, El Paso, Texas 79935. 20 Empire Scientific Corp. 22 FISHER DETECTORS introduces new 1972 models! Free litera- 21 GC Calectro 98, 99. 100. 101 ture. FRI, Dept. PE -2, Palo Alto, CA, 94303. 22 Grantham School of Engineering 13 23 Gregory Electronics Corporation 124 TREASURE Hunters! Prospectors! Rockhounds! Find Hobbyists! 24 Heath Company 108, 109, 110. Ill gold, silver, relics with world famous Detectron Metal Detectors. 25 Johnson Company. E.F. 8 Free information. Delivery immediate. Detectron, Dept. 2 -PE, Box 243, San Gabriel, Calif. 91778. 26 Lafayette Radio Electronics 113 27 Lendell Products 105 28 Liberty Electronics, Inc. 122 MUSICAL INSTRUMENTS 29 McGraw-Hill Book Company 12 30 McIntosh Laboratory Inc 104 31 Magitran Corp. 89 30% DISCOUNT name brand musical instruments. Free catalog. National Radio Institute SECOND COVER, I. 2. 3 Freeport Music, 127-N Sunrise Highway, Freeport, N.Y. 11520. National Technical Schools .. 54, 55, 56, 57 32 WHOLESALE! Professional Amplifiers, PA Systems, Guitars. Free Olson Electronics 106 Catalog. Garvin, Escondido, Calif. 92028. 33 PTS Electronics, Inc. 114 34 Poly Paks 121 REAL RCA Institutes. Inc. 18. 19. 20. 21 ESTATE 35 Sams & Co.. Inc.. Howard W. .- 87 36 Sansur Electronics Corp. 69 FREE ... NEW ... 256 -page Spring Catalog! Describes and pic- 37 Schober Organ Corp. The 105 tures hundreds of farms, ranches, town and country homes, busi- 38 Shure Brothers. Inc. 67 nesses coast to coast! Specify type property and location pre- 39 Solid State Sales 118 ferred. UNITED FARM AGENCY, 612 -EP West 47th St., Kansas 40 Sonar Radio Corp. 116 City, Mo. 64112. 41 Sony Corporation of America 25 42 Southwest Technical Products 104 MISCELLANEOUS 43 T D K Electronics Corp. 81 44 Tektronix. Inc. 77

45 Telex Communications Division 14 46 Trigger Electronics WINEMAKERS: Free illustrated catalog yeasts, equipment. Sem- 89 plex, Box 12276, Minneapolis, Minn. 55412. 47 Turner Division. Conroe Corporation 115 U.S. Air Force 83 STOP unauthorized keys that work your locks. Send $2.00, Luse U.S. Army 38. 39 Enterprises, Dept. P.E., 2902 East Altadena Avenue, Phoenix, U.S. School of Music Arizona 85028. 9 48 Valparaiso Technical Institute 103 YOUR Classified or Display Classified Ad in these columns will be CLASSIFIED ADVERTISING 117. 118, 119, 120 seen, read and regularly responded to by America's largest 121. 122. 124. 125 audience comprising Electronics Professionals and Hobbyists. Cost is low, results high. Send copy and payment now!

FEBRUARY 1972 125 MEW IDEAS!' LIVE IN THE WORLD OF TOMORROW-. ...IOW! NEW -PRODUCTS,- NEW MATERIALS; - UNUSUAL & PHYSICAL' LIENCE BUYS.. UNIQUE HARD -TO -FIND BARGAINS FOR FUN, STUDY OR PROF' o K

$15,000 RANGEFINDER HELIUM BALLOONS MAKE A "BALL" TREMENDOUS WAR sUlttLUS VALUE "41 Anytime there's a halloon the air is Tes- rellene ro Milton. dlark 57. 510,1 (1. yEr, s_ " tire. golly when the "air" Is Ile - -. mule, Erect linage Coincidence Range- I --"' 3 Mint trhichWhich nt, kes a balloon perky and 25 the finder -range! from 100-1t1,110í1 yds.. fadventurous Now here'. times dograte to 12 -arre mes, optics av un-2Sr various colored balloons of 4. al alone worth more than price, ,..---..5`.4._.. -_ 5. or 0" diameter when inflated. With 4r.0 lows precision .pílete Instrument. j.1 n pr,.ssol'Ixed lbs sq. , . them, ,300 .Í'X7^ Ha. Yellow. anos neutral. oat, T1 0 t: containing 21 liters of helium to In riring & clear war glans tillers. \an- inflate :Ill 25. For adtrlta or hills' Par- , rXt".: " he'iring tinR -aura).. bazaars or just teco- magneticagnetr ties, give u (ItRX.'las 0.11. & In lns1\fit_ ' i " ,.nstl':,ling "Ilgliler than air". Helium 0.0.i. a_t box, Luso'.. ^ o . ii is a safe nootoxle inert gas, No. 85,208AV ...... 15hop9. IA t.-200...... , ,^ .:;; -p l2 Stock No, 71,289AV 53.00 Ppd 51.250 HAND HELD 50 CM MODEL No. 85.213AV (Shpp9. Wt. -11. -lbs.) $600.00 F.O.B. NUMERICAL INDICATOR TUBES Hest; -toed as dried tfne. side -view I ad- PRECISION MICRO SCREWDRIVERS orn devices for basic counter tl corn - puler circuits. Gas WhathatWhat rold'ralbndr Set of IU lo( quality Professional sorely. erica) adout takes use t of ,n ,trivtw vilh blade widths ranging from mode. I0 ( cathodes In shapes nu- 11.0 lo: (.Haba: i-or Hoe Precision n'ork, merals 0-0, Also give visual digital Ms. intricatetr'icate assembly. Invaluable for hobby- ' play of volts. t -veles. etc. High ,clear. ists, camer a. instrument and eleclronics ,Y j/Y q I,Ilfty. long IIre: hide -:angle viewing ir Pal''.. teed foul watchmakers. newel- ! with trrightaess and stahilily. e Handy ,ivivel ler..e 'Iii TUBE W,o DECIMAL: sldtsi tempered Steel blades. Width Of /l /f No. 41.593AV 55.95 Ppd. rle'lyudriVe ir oagh acretie Socket for above: CM'vrrrf'art . u-tlumngh Plantic No. 41.616AV ....80C Ppd. Stock . TURK W DEC -TO -LEFT: Stock No. 41.6]1 AV 54.00 Ppd. No. 41.618AV 55.95 Ppd. Socket for above: No. 41.617AV 801 Ppa. POWER HORN BLASTS A MILE S8.95 ELECTRONIC STROBE Fright,' prowlers. uggers. viciose Ilandsi2Od solid stale electronic`electrons strOSe ,log. oath 118 decibels, Aunt press and light at fantastically price. Pro. this P1'1mn Powered our kel-sited metal Mires bright psychedelic effects like horn ran h, heard a tulle away to signal Xenon for hell, Or fort. eat for, homing Ill larger. far more expensive sea- strobes. via Ills Just to X 4 X IaM- floats,. hiking. camping, hunting. Bash Pni'oxi- shore. rooting. for your leant, Can IC thi,'k. A,i)u.lahle heard over U'Nell, and constr. noises to n Iately 7.10 flashes per u second. Slake ou motion neck. Poster. ome alive. gnil fired drill, lunch hunk ormer- Great to take with You to parties, anc)'. Weighs only :( n' but contains dances, outing. etc. Requires 2 9v hp to 100 mile-Ptereing 1las10. :\ 1-0:11 transistor haft. (not Incl. ). tnstructl ens. balafli n. Stock No. 41.443AV ...... 58.95 Pea. Stock No. 41,423ÁV ....$3.25 Ppd. 4 REPLACEMENT LAMPS AV 2 Refill Cartrs.(P-41,424ÁV) 52.75 Ppd, P -41,444ÁV 1 00 Ppd. "FISH" WITH A MAGNET BLACK -LIGHT MIGHTY MITES GO treasury hunting o, the bottom! Relatively small (12''l fixtures give sur- Fascinating fun & so ollrnts prod:,ble: prisingly Aright black'lighl. 51fr'''or'- 'lie a line t0 our 5. -II.. Sl:tgnel-dine hay, lake ocean. : finished reflector makes Instant star, t overboard In rive'. or Ire H -watt. high-into:1,d , hulk Iok Troll it 0101.0 1...U.0111 -your 'll'eas,0e,1' like MI -waiter. lip 01 MOO hour's of Wall elm he 01 111011rd Motors.bur's. anchors. safe, long black -light to Other metal valuables. -11,. a21agnet -wave 1Ní0/1Á1 is surplus-Alnico50 Bally turn on parties. 111110 &11íi, rV51 Typo -govt. 0. psychedelic decors, holiday der- ta tin $at). Lifts over Ihs, on 1ant1- oralior s. Shockproof end -ºos , mowe notch greater sleigh is tinier water. (Or safe.e. easy r'e nlacenlent of h,rlh and Ppd. _ tarter. Stands upright or hOri20n1:11. No, 70.751AV .. Sí/2 lbs...514.00

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PSYCHEDELIC LIGHTING HANDBOOK NEW ! ELECTRONIC DIGITAL COMPUTER KIT! 11111 Information packed Pages: Fully Sulo'e problem.. play g:uuex. predict explains latest In psychedelic lighting weather with this actual tvorkinr, del Iummeni, technlilues. developments. giant eleelronir ,l o'ains. Amazing nett. Covers all f:re,Is of Psyrheil,llc It'r- tam wayy to learn all tout computer strobes. ofa production including logic, decimal. lo. tOt i, ink lights. projectors. crystals. or. nary st!telltt. of 110 4115;MvL game slid,s, miles,'., color organs. po- your Progranmling alter completing larized color. light linxes. 5tio,eVinlon. simplified 110 page instructve booklinclude' .. etc, Shows how to 'Psyrhedeliee" par- seep -byI1.aas -step dia- .1Hp8""'" ties, musical groups. shows or how to grams. Circuits easily changed. Newhall Iff//1/lIÍ. set up -electric taps" for private from illuminated control Refl.ter 2 gatherings. St.," x I I' looseleai' paper '0" halt, toot im l.,. Nell we'vet t, , for seen -tor hone, sehOol. Indstry. :. ,._. Stock No. 9100AV 53.00 Ppd. Stock No, 71,434AV (11'X121/=^XT") $31.50 Ppd. AMAZING NEW Wankel Engine KIT!

. Thrill to the fun of building your own MAIL COUPON FOR sale -through l,olol'ioe,l model of levo- lationl,ry plstnntss type Rogan,. right. for which Gil 'errmly mild S.5í toll. hone nab' engine experts think e-o- GIANT FREE CATALOG!. mically modifiable to meet new póñu - tlun standards. Replaces. inton, der. crank Luhlies with of:ilinl THAN erlio nmovr,l for Hying eh:ln,. 148 PAGES MORE hers, ,:dl,r than r m'enitonal: lower BARGAINS! part.. greater samem 'p(ied 4000 UNUSUAL less horsepower. Feat: bashing pros, Completely new Catalog. Parboil with huge -TiberI fall hell. st lek-,hilt m,-011 !witch. selection Of telescopes. microscopes.icstopes.r, binocu- IteO. "-I.',V lull1. inut Inel.l, la'' ,agnets. magnifiers. prisms. plhOlo corll- No. 71.424AV (41/2^x5"xS") 56.75 Ppd. 0400` Poilritis, , allogy and l'nhlne Lighting items. Pmts. kits accessories -many bard -to -get sto- plus hargaius. 100's of charts. illustrations. NEW LIGHT -EMITTING -DIODE KIT For hobbyists. experimenters. schools. imlustry. Bargain kit Ideal for economical expo'''. "tenting with amazing I...O.s,I: the Lilly solid sate monochromatic lamps that EDMUND SCIENTIFIC CO. I0,' volt Cge 1)(.. last up to 12151 N.J. 08007 hiii''l,, Used In tit -Igoe readers. charge 300 Edscorp Building, Barrington, ter recognition. h1.01ied detectors. all Please rush Free Giant Catalog "AV" kinds of elecl,'o-8Plivnl applications. hie [nets :1 i..t:_it s: g: alum :e-nrtoide Name ,511,1:11111111, 511' . i, f1I,R11 11:10t: 2 vi!i. her red emitting .(1(100 A°1: I infra -'red /11 Address Hitting' kí00 A": 11 resistors; I 2inm pl +tc fibre optic light Pine: Stern. City State 7ip Stock No. 41.59 ]AV 55.95 Ppd

ORDER IV STOCK MOMEE. SEND CNECB O. MONET O11DEE MONEY -RAC[ GUAR/Mitt.. EDMUND 3.00 EDSCORP BLDG¿. ' SCIENTIFIC CÓ. BARRIN,GTO_,NNEW JERSEY 08007 CIRCLE NO. 18 ON READER SERVICE CARD 126 Printed in U.S.A. SYtwiIHE MOSI 1MPORIANI DISCS IN YOUR ENTIRE COLLECTION! Stereo Testing I Spectacular Sound I -- .....-. ::::11 STERE TEST Nowt9Rnna, REC$RD Model SR12 _ - --, :-- -s BINAURAL IKJME DLABÓIVaTORv lL9Eo STEREO TEST DEMONSTRATION

RECORD RECORD

The most complete . most sophisticated ... most Binaural recording re-creates the directions, distances, versatile Test Disc available today. Whether you're an and even the elevations of sounds better than any other avid audiophile who'll settle for nothing but peak recoraing method. The super -realism of binaural record- performance from his stereo components ... a casual ing is accomplished by recording the acoustical input for listener who'd like more insight into the challenging each ear separately, and then playing it back through

world of stereo reproduction . . or a professional stereo headphones. Thus the sound intended for the left technician who needs precise standards for lab test- ear cannot mix with the sound for the right ear, and vice versa. ing . .. the SR12 is a must for your record collection. Binaural recording offers the listener the identical acoustical perspective and instrument spread of the original. Make these important stereo checks BY EAR . Frequency response track- The sound reaching each ear is exactly the same as would Separation , Cartridge have been heard at the live scene. ing Channel balance Hum and rumble Flutter Cartridge and speaker phasing Anti -skating adjustment "Gun shot test" for stereo spread Multi- STARTLING REALITY. The Binaural Demonstration Record purpose musician's "A." Equal -tempered Chromatic offers 45 minutes of sound and music of startling reality. octave Guitar -tuning tones. You'll marvel at the eerie accuracy with which direction and elevation are re-created as you embark on a street

tour in binaural sound-Sounds Of The City . Trains, 7 . Attention critical TEST EQUIPMENT checks Planes & Ships ... a Basketball Game, a Street Parade. professionals: SR12 is also designed to be used as a a Street Fabrication plant, The Bird House at the Zoo-all highly efficient design and measurement tool. In the demonstrating the Incredible realism of binaural sound following tests, recorded levels, frequencies, etc. reproduction. have been controlled to laboratory tolerances-afford- ing accurate numerical evaluation when used with MUSIC IN BINAURAL. The musical performances pre- oscilloscope, chart recorder, output meter, intermodu- sented on the Binaural Demonstration Record transport lation-distortion meter and flutter meter. you to the concert hall for a demonstration of a wide variety of music. Selections total 23 minutes, and Include Sample waveforms-illustrating both accurate and examples of jazz, organ, and chamber music. faulty responses are provided in the Instruction The Stereo Review Binaural Demonstration Record is the Manual for comparison with the patterns appearing ultimate in sound reproduction. It has been made without on your own oscilloscope screen. compromise.

SEND NO MONEY - YOU WILL BE BILLED $5.98 EACH, POSTPAID Use the postage -paid order card located at the top of the flap to the #'s on the Information Service Card to the right. Either way, right to order your records. In the event the card has already been your selections will be mailed to you along with an invoice for detached you can also place your order by circling the appropriate the regular price of only $5.98 for each record ordered, postpaid.

SR12 STEREO TEST RECORD - Circle #110 BINAURAL DEMONSTRATION RECORD - Circle #113

Popular Electronics i.On the attached postage-free card, print or type INCLUDING Electronics World your name and address on the lines indicated. READER SERVICE 2e Circle the number(s)that corresponds to the (free information) key numbers) at the bottom or next to the Here's an easy and convenient way for you to advertisement or editorial mention that is of interest get additional information about products to you. (Key numbers for advertised products also advertised or mentioned editorially (if it has a appear in the Advertisers' Index.) reader service number) in this issue. Just follow the directions below ... and the material will 3. Simply cut out the card and mail. No postage be sent to you promptly and free of charge. required. PROBLEM: Two stereo phono cartridges are about equal in tracking ability, and all other pertinent specifications are about on a par. Both are priced in the $65-70 range. Which one should you choose?

-J

You have chosen a highly -rated, very popular cartridge. But to get flat response at home, you'll have to add a capacitor to each input, or measured lengths of cable of specific capacity. This will "kill" i the peak you see here, but the Hi -C) mechanical resonance that caused it will remain. It won't sound bad, but it could be better!

il. == _ , :.. _.. >Q,, __. ,1.- +,z eiesiaiseiies- issiiseiissii Congratulations! You have chosen the newest magnetic cartridge on the market. The dual -magnet STEREO -V Model V140E by Electro -Voice. It offers flatter response with no need to monkey around with I. capacitors or special cables. And it equals or exceeds every other performance "i specification of its famous rival. Because STEREO -V cartridges are new, and sound so great, they may be in short supply. j'" ,. Even so, don't accept a substitute, no ;r matter how well-known. Fame is no sÍestelesileee'iiTi'liif`i=i`i=fFiiissisessesiii guarantee of perfection.

NOTE' Respon..e shown horn 50010 50 000 Ht d.m,l-. 0' :n.. r OS ST It 120 h wl n. .no.,n ncv ,, nc, .5 CharaCler.it,< ol !cc. ,e

d. } i

II you would like to know more about STEREO -V'' cartridges, B new STEREO -V models permit you to we have a new catalog describing the complete line, select the tracking ability that best sults your each designed to give you optimum performance no matter record player. But no matter which cartridge what kind of record player you use, or what your budgetary you choose, from 519.95 to 5150.00, you'll get limits are. It's at leading sound showrooms, or write flat response over the entire audio range. ELECTRO -VOICE, INC.. Dept. 224P, 630 Cecil Street. Buchanan. Mich,Oan 49107 In Canada: E V of Canada 110. 345 Herber: 5lreel. Ganano0ue. Onta.lo In Europe: EIocI,OVO,Ce, 5.4., LysaS(,asse 55. 25E9 Nidau. Sw,Ire,land. Jlecrolen a GULTON subsidiary CIRCLE NO.- 13 ON READER SERVICE CARD