HOW TO "READ" FM TUNER SPECIF CATIONS ectronlcs WORLD'S LARGEST-SELL/NG ELECTRONICS MAGAZINE JANUARY 1975/75¢

PROJECT BREAKTHROUGH I World's First Minicomputer Kit to Ri,al Commercial Models.•. "AlTAIR 8800'4t SAVE OVER $1000

ALTAIR eeoo --__ -, ...... W I ~ - "m •••.-:: ••M a n: •~ •, mrn : ; ~ : l l ! ! - - d m ~ m ~ ~ U U B U _., U u 0 U M tt , .- . . . ' .. .. I .• ' ' .' ' I ' ' ' .. ' I I ' . . I ' f t . > f ti 14 ll ti ll 1• t I f • I 4 J t 1 I .. " ' ... - =. F='\. ~~ ;

ALSO IM THIS ISSUE= • An Under-$90 Scientific Calculator Project • CC D's-TV Camera Tube Successor? • Thyristor-Controlled Photoflashers TEST REPORTS: Technics 200 Speaker System Pioneer RT-1011 Open-Reel Recorder Tram Diamond-40 CB AM Transceiver Edmund Scientific "Kirlian" Photo Kit Hewlett-Packard 5381 Frequency Counter

18 101

switched turnover bass and treble controls for more precise tonal compensation tor room acoustics and other program source characteristlce. In thetr respective price rangea, these are unquestionably the finest values in stereo receivers the.world has ever known. Audition their uniqueness at your Pioneerdealer. $<-1"010 -$699.95; SX-939-$599.95. SX-838 - $499.95. Prices Include walnut cabinets. Master control •.,.... capablllty Also new and more Pioneer's engtneers have surpassed moderately priced. themselves wlh a combination of control features never before found Pioneer's most complete and finest In a single reoeiV&r. All !hree units line of receivers ever, presents lncfude: puatrbutton functkm selection equally outstanding values starting at with illuminated readotltB on the $239.95. Shown here are the SX--535 uttra wide tuning dial, FM and audio -$299.95, SX-636 - $349.95, SX-737 2 2 2 muting, loudness contour, hi/low - $399.95. All with walnut cabinets. 2 2 1 filters, dual tuning meters and a U.S. Pioneer E1ectronics Corp., 1 1 1 dial dimmer. 75 Oxford Drive, Moonachie, 1 1 Never before used on a receiver New Jersey 07074 are the twin stepped bees and treble West: 13300 S. Estrella, Los Angeles a 3 3 3 tone controls found on the SX-1010 90248/Midwest: 1500 Greenleaf, ! ' 3 2 2 and SX-939. They offer over 3,000 Elk Grove Village, Ill. 60007/Canada: :&/4-ch. S.H. Parker Co. tonal variations. A tone defeat 2 2 1 switch provides flat response ••3JPK:.tion 1 1 1 instantly throughout the audio ...... _IMPX 1 spectrum. The SX-838 features when you want something better

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SX-535 SX-636 SX-737 Earn an extra $2000 per year Find out how you can earn an extra $2000 or more per year re­ storing only a few color and black and white tubes per week. Full color brochure shows you how to make more money and sat­ isfy more customers on al­ most every call. Write to­ day!

New /Bi/( 467 CRT RestorerI Analyzer $279* With the profit restorer! Profit in the home. After replacing a component TriDynamic true test. The B & K Tri Dynamic method you 've often noticed a less than perfect picture. It's tests all three guns simultaneously. It measures true almost always due to a weak picture tube. The few beam current that passes through G1 aperture, unlike minutes you spend with the 467 Restorer will give other testers that measure meaningless cathode to G1 your customer brilliance and sharpness that will make current. Leakage indication even includes cathode­ her pleased to pay for the improved picture. to-cathode and there's an exclusive B & K focus con­ tinuity test. Profit in the shop. " Sixty-five dollars and the picture still doesn't look as good as it used to!" How many Simplest operation. Exclusive integrated circuitry times have your customers said that to you? You need lets you test all picture tubes with the same, defined­ not hear it again! Use the 467 Restorer on every major on-the-front-panel procedure . . . including " in-line" , job and your customer will thank you for returning his Trinitron and tubes with common G1 and G2. See your set working like new. distributor or write Dynascan. *S ix socke ts included; op tional sockets al so shown. Most-Powerful Rejuvenation, but most gentle too. There's only one CRT Restorer that restores the pic­ ture to like new and analyzes tube condition so ac­ curately that you can safely guarantee restoration for up to five years. You get extra safety from our auto­ matic restoration method that prevents cathode /Bf/fg~J{§~AN stripping. Chicago, IL 60613 • (312) 327-7270 • CIRCLE NO. 7 ON READER SERVICE CARD 2 POPULAR ELECTRONICS JANUARY 1975 VOLUME 7, NUMBER 1 Ponnlar E!~~£!!~!!N!~~® FEATURE ARTICLES THYRISTOR CIRCUITRY FOR ELECTRONIC PHOTOFLASHERS •..••..••....•.•••...... • Michele Frank 39 An SCR trigger provides faster recycling, more flashes and quick recharge. SOLID-STATE IMAGE SENSORS-TV CAMERA TUBE SUCCESSOR? •. • .... Harry Garland & Roger Melen 43 KEYING AND VCA CIRCUITS FOR ELECTRONIC MUSIC INSTRUMENTS, PART I .•••••••• •Don Lancaster 60 HOW TO " READ" FM TUNER SPECS ...... ••.•.•••.••.....••••..•.•••••••••.••.•••.•Julian D. Hirsch 68 LIGHTNING DAMAGE INSURANCE JOBS .• .•••.•...... •..• • ....• • ...•• •• ...•...•. •••. . .. . • John T. Frye 72 How lightning damage occurs and how to prevent it.

CONSTRUCTION ARTICLES

ALTAIR 8800 MINICOMPUTER, PART I •••.•.•...... ••..•.•...•..•. H. Edward Roberts & William Yates 33 The most powerful minicomputer project ever presented- for under $400. AN IGNITION TIMING LIGHT FOR IMPROVING GAS ECONOMY •• ... ••...... • •••....•. Anthony Caristi 50 BUILD AN UNDER-$90 SCIENTIFIC CALCULATOR ...•.•.•..•••••.•...... •••••••...•...•.. Martin Meyer 53 Ten-digit, full-function, pocket-size. IC SPEED CONTROLLER FOR HO MODEL RAILROADS ...... •.....•...... •....•.. Robert D. Pascoe 58 BUILD THE TRANSISTOR IDENTOMETER •..•...... •.....••...... •...... •..... John T. Bailey 69 Identifies leads and polarities and shows up bad devices. SIMPLE SQUELCHING CIRCUIT FOR STEREO FM TUNERS •..••.•••••••.••••.•••• Lawrence N. Dworsky 71

COLUMNS STEREO SCENE ...... • . . ...•...•.•..... •.•...... • •• ...... ••..• •. •.• • ••...... •.••. . Ralph Hodges 22 Mikes and miking. SOLID STATE ...... •... •• •••••••••••••••••••.•.•••.•.•...... , .••• , , , .•••••••••. Lou Garner 88 Predictions for 1975. CB SCENE ...... ••...... •.... .••.•...... •.•...... • •...... •.... • ..• • •••••• .. • Len Buckwalter 92 CB's Red Baron. AMATEUR RADIO ...... • ...... •••• . .• . .. . •. .• ••• .• ••• . • ..•..•..•.... •• . Herbert S. Brier 94 Reception and the atmosphere. TEST EQUIPMENT SCENE ... .••. . ..•...... ••...... • ••. .•.....•. •••• • • ••.•. •• . Leslie Solomon 98 Rejuvenating elderly equipment. HOBBY SCENE ...... •...... •.. • . •...... •••.. ... • .•...•...... ••....•..•.•.. Editorial Staff 102

PRODUCT TEST REPORTS TECHNICS BY PANASONIC MODEL T-200 SPEAKER SYSTEM ...... • .. • . . . .. • • . • • • .. . . . • • .. .. • ...... • 78 PIONEER MODEL RT-1011L STEREO TAPE RECORDER • ...... • . . . . • . • • . • . •• . . . . • . . . . . • . • ...... • . . 79 HEWLETT-PACKARD MODEL 5381A FREQUENCY COUNTER •..•....•.•••.•• , . • . • • . • . . • . . . • • . • • • ...... 80 TRAM DIAMOND 40 AM CB TRANSCEIVER • . . . • ...... • . . . . . • • • • • • • . • . • . • . • • • • • ...... • . • . • • • • • ...... • . 81 EDMUND SCIENTIFIC KIRLIAN ELECTROPHOTOGRAPHY KIT ....•. ; . . . . . • • • • • . • • . . . • • . . • • • • . . • . . • . . • . • 82

DEPARTMENTS EDITORIAL .••...... ••. . .•.....•...... •. . •...... • . •....•...... •.• •• Art Salsberg 4 The Home Computer Is Here! LETTERS ...... 6 NEW PRODUCTS...... 12 NEW LITERATURE ...... • .. • . • ...... • ...... 16 NEWS HIGHLIGHTS ...... • • ...... • ...... • • . • • . . • . • . • ...... • . . . • • . . . • ...... • ...... • . . . . • . . . . 26 ELECTRONICS LIBRARY .• ••.• ...... •...... •.•.•...... •...... •....•...... • 100

POPULAR ELECTRONICS. January 1975. Volume 7. Number I. Pub· Z1fl-Dav1s also publishes Boating, Car and Dnver. Cycle. Flying. Mod­ lished monthly at One Park Avenue. New York . NY 10016. One year sub· ern Bride. Popular Photography, Skung and Stereo Review scnpt1on rate for U.S .. Possessions and Canada, $6.98: all other countries. Forms 3579 and all subscription correspondence should be addressed $8.98. Second class Postage paid al New York . NY and at addi11onal to POPULAR ELECTRONICS. Circulation Dept .. P 0 . Box 2774 . Boulder. ma1 hng offices. Authorized as second class mail by the Post Office De­ CO 80302. Please allow al least eight weeks for change of address. In · partment. Ottawa. Canada and for paymenl of postage in cash. Subscrip­ elude your old address. as well as new- enclosing. 1f possible. an ad· llon service and Forms 3579. P 0 . Box 2774. Boulder. CO 80302. dress label lrom a re cent issue. POPULAR ELECTRONICS Including ELECTRONICS WORLD. Trade Editorial conlributions mus! be accompanied by return postage and 1 1 will be t1andled with reasonable care: however publisher assumes no M~~~~~ 1~::i'id ; ~~i4xe8~n i~:F~6~~~~s ~J~t~~~i~Gog~~~~~~tu~tL respons1bih ty lor return or safety ol art work. photographs. models. or RIGHTS RESERVED . manuscripts. JANUARY 1975 3 &lP-nlar Electronics "

EDGAR W. HOPPER Puhli lu·r

ARTHUR P . SALSBERG J.;,Ju orwl IJ1rector Editorial LESLIE SOLOMON "frcl1111 cul £d11 ur

JOHN R. RIGGS \fmwgi 11g E11itor

EDWARD I. BUXBAUM .· \ r l l)irfcltJr THE HOME COMPUTER IS H ERE! ALEXANDER W. BURAWA Assodfltr l::tlitor For many years, we've been reading and hearing about how JOHN M cVEIGH computers will one day be a household item. Therefore, we 're .·\ 'i:S1sta 11 t Editor especially proud to present in this issue the first commercial type ANDRE DUZANT of minicomputer project ever published that's priced with in reach fl·d111 icul 11/ustmlQr of many households- the Altair 8800, with an under-$400 HERBERT S. BRIER complete kit cost, including cabinet. LEN BUCKWALTER LOU GARNER To give you some insight to our editorial goal for this momentous GLENN HAUSER project, we were determined not to present a digital computer JULIAN D. HIRSCH RALPH HODGES demonstrator with blinking LED 's that would simply be fun to build WALTER G. JUNG and watch, but suffer from limited usefulness. High chip costs ART MARGOLIS Co,1trilmti 11 g Etlitor,\ would have made this a most expensive toy. What we wanted for

JOSEPH E. HALLORAN our readers was a state-of-the-art minicomputer whose ,\ rlrerlisw e /)irectol' capabilities would match those of currently available units at a

JOHN J. CORTON mere fraction of the cost. .-\ tlt1 1rt 1.!ii11g alt''­ After turning down three computer project proposals that did LINDA BLUM not meet these requirements, the breakthrough was made possible ,·\ rlrcrllsm,z Sen 1cr \ftm111;1·t with the availability of the Intel 8080 n-channel CPU (central PEGI McENEANEY processor unit)- the highest-performance, single-chip processor £xcculit.t' :\s:nstuu t available at this time. As a result, Altair 8800 offers up to 65 ,000 STANLEY NEUF ELD words of memory, 256 inputs and outputs simultaneously, buss .4 $..itlJCrfltt• P11M1slicr line expansion, subroutines that are enormously deep, and fast FURMAN H. HEBB cycle time, among other desirable characteristics. Peripheral Cru1111 \'I', E/c,· t rc.>111c~ & Plwto equipment such as a " smart" CRT terminal is expected to be ZIFF·DAVIS PUBLISHING COMPANY available, too. to make up a within-pocket-book-reach Popular Electronics Editorial and Executive Offices sophisticated minicomputer system. One Park Avenue New York. New York t0016 212·725-3500 Unlike a calculator- and we're presenting an under-$90 Hershel B. Sarb1n. President scientific calculator in this issue, too- computers can make Furman Hebb, Execu11 ve Vice President and Treasurer Phillip T. Heffernan. Senior Vice President, Marketing logical decisions for an accounting system . navigation computer, Ed ward D Muhlleld . Senl or V1cePresiden1. SportsD1v1s1on time-shared computer, sophisticated intrusion system, and Philip Sone, Senior Voce President Frank Pomerantz. Vice President, Crea tive Services thousands of other applications. The " power" of Altair8800 is such Arthur W. Butzow. Voce President. Producti on that it can handle many programs simultaneously. Lawrence Sporn. Vice President. Circula11on George Morrissey, Voce President What we 're presenting to you , the POPULAR ELECTRONICS reader, Syd ney H Rogers. Vice President Sidney Holtz. Voce President therefore, is a minicomputer that will grow with your needs, rather Charles B Seton. Secretary than one that will be obsoleted as you move more deeply into Edgar W Hopper. Voce President. Electronics Div computerized applications. With minicomputers exhibiting an Woll oam Zoll . Chairman annual growth rate of some 50%, according to the E.l.A., and with W Bradford Briggs. Vice Chairman predictions that six out of ten computers sold by 1975 will be Midwestern Office min i's, you can be sure that there will be manifold uses we cannot The Paw s Group. 4761 West Touhy Ave .. Llncolnwood. llhnoos 60644. 312 679-1 t OO even think of at this time. GERALD E. WO LFE. GEORG E B. MANNION DAVID ALLEN There'll be more coverage on the subject in future issues. Wes tern Office Meanwhile, the home computer age is here-finally. 9025 Wilshire Boulevard. Beverly Hills. CA 90211 213 273-8050. BRadshaw 2-t t6t Western AdverllSJng Manager, BUD DE AN Japan '. James Yagi Ojo Palace Aoyama . 6-25. Monamo Aoyama 6 Chome. Monato·Ku. Tokyo 407-1 930/682t . 582-2851 , --· • I • ,...... I I • . ' ~ • <' ,,,'. 11 Membe r Aud1. ,B ureau *'"""l°' ··-·- ..0.0 1oec urr of Circulaf1on s

The publisher has no ~now lcdge of any propro tary r1gh ts whoch will be violated by the making or using of any items disclosed 1n this issue. 4 POPULAR ELECTRO NI CS Radio Shack deals ... from the top of its decks! The top of our Realistic® line. An Auto-Reverse Dolby deck for 2-hour stereo recordings without flipping the cassette

The Realistic SCT-7 with Auto-Reverse. What convenience! You can record or play an entire concert, on both sides of the FREE New 1975 tape, for two uninterrupted hours. Or record or play on just one side with Auto-Stop. Or play an entire cassette over and Radio Shack Catalog over without stopping. The SCT-7 does it all-automatically. OVER 2000 PRODUCTS And what features and sound! Dolby* noise reduction system. Bias switch for Cr02 or standard tape. Record edit button to EXCLUSIVES ON EVERY PAGE insert silence between selections. Headphone jack. Big , BEAUTIFUL FULL COLOR illuminated VU meters. And lighted indicators for record, tape Stereo •Quadraphonic •Phonographs travel direction and Dolby . UL listed. What a deal! #14-897. 'Dolby is a trademark of Dolby Laboratories, Inc. TV Antennas •Radios •Citizens Band Kits •Recorders •Tape •Tools Auto Tune-Up •Electronic Parts Test Instruments •More!

1 64 pages of the finest in home and hobby electronics Respected brand names like Realistic, M icronta. Archer. Science Fair - and they're available only at Radio Shack stores and dealers nationwide' See what's really new in electronics by getting this catalog now. The Realistic TR-801 with Digital Timer. It couldn't be easier to use. The unique timer shows the minutes and seconds re­ corded on each cartridge-you always know exactly how much SEND FOR YOURS TODAY! time remains. And pushbuttons control everything. Auto-Stop FILL OUT COUPON BELOW and eject at the end of each program or just program-4. Repeat and continuous play. Pause and fast forward. Manual power­ 467 1975 Mail to Radio Shack, P. 0. Box 1052, eject. It makes you a recording pro. U.L. listed. #14-925. C atalog Ft. Worth, Texas 76101. (Please print.)

Na.me ______Apt. No. ___ There's only one place you can find them ... Street ______

City______~ .U rlad10A TANDY CORPORATION lhaeK COMPANY Smte ______ZIP aMaster Chargee or ] OVER 3000 STORES • 50 STATES • 7 COUNTRIES Bank Americard at L _ -----______----__ _J participating stores Retail prices may vary at individual stores and dealers. CIRCLE NO. 31 ON READER SERVICE CARD JANUARY 1975 5 PE ON THE AIR Just a note of appreciation for the new larger format. You have made a great magazine a lot more enjoyable. Over the years, I have used or adopted a number of ideas presented in POPULAR ELECTRONICS ~I here at radio station KORI (FM), a trick that often saved a great deal of time-let alone Letters the money involved when equated against the cost of commercial equivalents. TOM WIRCH Chief Engineer * The Most Advanced KSLM/KORI (FM) "OPTO-ELECTRIC SYSTEM" Salem, Ore. • The Allison Breakerless System eliminates the Points and Condenser, replacing them wtth an Opto-Electronic RUMOR IS NO SECRET Trigger. using a Light-Emitting Diode and Phototransistor. THE PARTS PROCUREMENT DILEMMA Also completely eliminates wiper-arm "friction" wear. I was surprised to discover, in your Oc­ The only " TRUE " Electronic Ignition ... that you can install tober issue, that Radio Canada Interna­ I would like to build the " Nine-Channel for under $100. Gives 40-times more Timing Accuracy than ANY system using mechanical Breaker-Points! tional is engaged in " clandestine" broad­ Stereo Equalizer" (May 1974) but I am hav­ Unlimited RPM. Smoother running .(No timing fluctuation casting to Russia from Sines in Portugal, ing difficulty finding a dealer who handles as with Magnetic units). Unaffected by Temperature , Moisture, or Vibration! All Solid-State Components. over a station which (as stated on page 56) the 5558 op-amp IC 's required. Another Easier Starting under any condition! Increased Horsepower. is "reported to be secretly owned by the problem is that no pin numbers are shown Sparkplugs last longer. Perfect timing increases engine West German gover·nment." for the IC in the schematic. Efficiency and Gas Mileage up to 30%! There was no need for the author to have • Quick and Easy Installation! JOHN E. RICE Tested and Proven reliability. recourse to rumors about the Sines trans­ Georgetown, Ontario, Canada * mitter, for what he advances as a con­ Only SATISFACTION GUARANTEED! s49?5 • spiratorial secret is published in a more You can obtain these /C's from South­ •complete. • 1-YEAR FACTORY WARRANTY. accurate version ... in the current World west Technical Products Corp. (see the (State Make, Year, Engine Size). (Calif. Res . add Tax) . Radio Handbook, page 92 , with cross re­ Parts List in the article for the address). As e CONVERT YOUR "C-0" UNIT TO BREAKERLESS! ferences as to users. for pin numbering, the omission was inten­ "TRIGGER-UNIT" ONLY $34.95 ALAN BROWN tional. The 5558 is available in several Send Postcard for FREE BROCHURE Today. * Radio Canada International package configurations, all with different ALLISON AUTOMOTIVE CO. Montreal, Can. lead identification. P.O . Box 881-P, TEMPLE CITY, CAL. 91780 CIRCLE NO. 2 ON READER SERVICE CARD In " Supressing Transients in Solid-State AN IC BY ANOTHER NUMBER Equipment" (July 1974), it was stated that The Exar integrated circuit used in my the General Electric 6RS20-SP4B4 thyrec­ COMING UP IN " Private Messages With a Voice Scram­ tor should be available at local electronics bler" project (September 1974) has a new stores. Well , I've tried six different stores THE FEBRUARY part number. It is now called the within a 20-mile radius of my home and XR2208CP. Please advise your readers of haven 't been able to locate one that hand­ this change. les this device. Can you help me with a Popular Electronics JOSEPH B. WICKLUND , JR. mail-order address? Northwest Engineering KENNETH L. METCALF Bothell, Wash. Woodstown, N.J.

Build the First, Low-Cost SETTING THE RECORD STRAIGHT The 6RS20-SP484 thyrector is available from Newark Electronics, 500 N. Pulaski Mr. Lancaster's series o.f articles on elec­ All-Solid-State lV Camera Rd., Chicago, IL 60624. However, there is tronic music synthesizers has served a use­ $25 minimim for mail orders. The GE dis­ fu I service to your readers. However, tributor nearest you is at 200 Main Avenue, " Selecting an Electronic Music Synthe­ Clifton, NJ 07014. AVU Meter with sizer" (October 1974) contains a few in­ accuracies: THE AMATEUR RADIO SCENE No Moving Parts 1. The ElectroComp 101 is manufactured ' by Electronic Music Laboratories (EML), Congratulations on the return of your which has no connection with EMSA; " Amateur Radio" column. I was very 2. The Synthi 100 is manufactured by pleased to see it in the October 1974 issue. I How Phase-Locked EMS (London) Ltd., who also manufacture can hardly wait for the next column to ap­ Loops Work live-performance EM systems that Mr. pear. My only criticism is that the column is Lancaster failed to mention. (The Synthi a quarterly; it should be a monthly. 100 sells for $30,000--not $20,000) ; Edward LeBlanc, VE1AMN 3. Electronic Music Studios of America, Prince Edward Island, Canada Test Reports: Inc., (EMSA) is not a manufacturer but the American distributor for EMS (London) In the October 1974 " Amate.ur Radio" Marantz 4270 Stereo Receiver column there appear to be two discrepan­ Garrard Zero 100 SB Turntable Ltd's products; Ortofon VMS-20E Phono Cartridge 4. EMSA and ARP do not have the same cies in · callsigns. The San Francisco Lafayette Com-Phone 23 CB zip code; EMSA's is 01002. station's callsign should be K101 , not Transceiver JANICE B. ANDRES K-101, while I believe the correct callsign Data Technology Models Managing Director for King Hussein is JY1-nor WJ1. 20 & 21 DMM's. EMSA Inc. Fred Becker Amherst, Mass. North Attleboro, Mass. 6 POPULAR ELECTRONICS The ''NEW LOOK" 1975 LAFAYETTE RADIO ELECTRONICS CATALOG

If you're interested in electronics you NEED this catalog! Completely re-designed for easier­ than-ever ordering, with the newest and best Lafayette and national-brand products for '75. And you get the same quality and service that has made Lafayette a leader for 55 years. Iron-clad guarantees! Lowest Prices! Professional Service! State-of-the-art Equip­ ment! Pick and choose from over 18,000 quality electronics products! Now, more than ever, we're your "Single-trip" shop­ ping center for everything in electronics.

SA VE 0 N EXCLUSIVE LAFAYETTE PRODUCTS PLUS THE BEST MAJOR BRAND NAMES • Stereo and 4-Channel Music Systems • Tape Recording Equipment • Car Stereo and AccessoJies • CB and Ham Gear • Police/ Public Service Receiv­ ers • Car Stereo and Accessories • Antennas • Cameras • TV • PA and Test Equipment• Music Instruments and Amplifiers • Books • Electronic Calculators • Security Systems • PLUS PARTS, TUBES, BATTERIES, HARDWARE - ALL YOU NEED FOR QUALITY LIVING THROUGH ELECTRONICS Lafayette Listen to us, you can't go wrong.

STORES COAST TO COAST Check Your Yellow Pages or Shop by Mall NEWI Bigger Pages Lafayette Radio Electronics 35015 111 Jericho Tpke., Syosset, L.I., N.Y. 11791 More Full Color NEWI D Send me your FREE 1975 Catalog. D Send a 1975 Electronics Catalog to my friend.

NEWI Easier-to-Read Type Name______Apt._ Name______Apt._

Street______Street______

City ______City ______free State ______Zip,___ State ______Zip.___ MAIL TODAY!

CIRCLE NO. 21 ON READER SERVICE CARD ARY 1975 •7 The real way to learn digital electronics! NRI is the only school to train you at home on a real digital computer.

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Learn computer design, construction, main­ tenance and programming techniques on your own digital computer using a professional digital multimeter! Qualified technicians are urgently needed for careers in the exciting new field of digital and computer electronics . . . and the best way to learn digital logic and operations is now available to you in NRI's Complete Com­ puter Electronics Course. This exclusive course trains you at home on your own digital computer! This is no be­ problem and displays the result instantly. ginner's "logic trainer", but a complete pro­ The NRI digital computer is one of 10 kits grammable digital computer that contains a you receive in the NRI Complete Computer memory and is fully automatic. You build it Electronics Course. You build and use your yourself and use it to define and flow-chart a own 3% digit digital multimeter ... while you program, code your program, store your pro­ perform hundreds of experiments, building gram and data in the memory bank. Press the hundreds of circuits, learning organization, start button and the computer solves your operation, troubleshooting andprogramming. 8 POPULAR ELECTRONIC Only NRI offers you five NRl's complete communication TV/Audio Servicing Courses course includes your own CB Training Transceiver

NRI prepares you for a career in the rapidly expanding field of com­ munications ... a field destined to double in the next decade! NRI can train you at home for one of the thou­ sands of service and maintenance jobs opening in AM and FM Trans­ Color TV repair is an­ mission and Reception, TV Broadcasting, Micro­ other big opportunity wave Systems, Teletype, Radar, Marine Electronics, field right now and Mobile Communications and Aircraft Electronics. NRI can train you at You train on your own 23-channel Johnson Trans­ home to service and re­ ceiver and AC power supply; a digital multimeter, pair any color or black for digital experiments and precise testing; bite­ & white TV, hi-fi equip­ size lessons leading to your FCC license and the ment, AM-FM radios, communications field of yout choice. and sound systems. You can choose from NEARLY ONE MILLION STUDENTS IN 5 courses, starting with a basic servicing course with 65 lessons ... up to a Master Color TV course, 60 YEARS HAVE LEARNED AT HOME complete with 25" diagonal solid state color TV in THE NRI WAY. handsome woodgrain cabinet. No other school offers Mail the insert card and discover for yourself why so many choices or so much value. NRI is the recognized leader in home study training. All courses are available with low down payment No salesman will call. Do it today and get started on and convenient monthly payments to fit your bud­ that new career. get. And all courses provide professional tools and equipment along with NRI-designed kits for hands­ APPROVED UNDER GI BILL on training. With the Master Course, for instance, For the career minded, we are approved for vet­ you receive your own 5" wide-band triggered sweep erans benefits. Check box on card for details. solid state oscilloscope, TV pattern generator, 3% digit digital multimeter and a NRI 25" diagonal MAIL THE INSERT CARD FOR solid state television receiver expressly designed for color TV training. YOUR FREE NRI CATALOG No salesman will call YOU PAY LESS WITH NRI TRAINING AND YOU GET MORE FOR YOUR MONEY. 1'.TRI employs no salesmen, pays no commissions. We NRI NRI SCHOOLS pass the savings on to you in reduced tuitions and rJ ~McGraw-Hill Continuing Education Center extras in the way of professional equipment, testing "JC"."'. • 3939 Wisconsin Avenue, instruments, etc. You can pay more, but you can't ltM j Washington, o.c. 20016 get better training. ARY 1975 11 "ISO-TIP" SOLDERING ACCESSORIES areas), and longer battery life. A meter is The Wahl Clipper Corporation has intro­ included for visual as well as audible indi­ duced a line of accessories for its " !so-Tip cation. Address: White's Electronics, 1012 cordless soldering iron. The Soldering Iron Pleasant Valley Road, Sweet Home, Kit (Cat. #7600) includes the iron itself Oregon 97386. (only 8" long and 6 ounces in weight) with a CIRCLE NO. 75 ON READER SERVICE CARD " safety lock" feature to prevent accidental tip heating, a wall mounting bracket, a bat­ tery recharging unit, a #7535 general­ PIONEER FRONT-LOADING CASSETTE DECK New Products purpose tip and instruction booklet. Op­ Pioneer Electronics' Dolbyized Cassette Additional information on new products tional accessories include #7545 fine tip, Deck, Model CT-F7171, features front­ covered in this section is available from #7546 heavy-duty tip, #7595 protective panel access for tape loading and all the manufacturers. Either circle the item's code numbet on the Reader Service Card carrier and the #7585 auto charger plug necessary controls. This allows the unit to inside the back cover or write to the man­ assembly that fits into a car cigarette ufacturer at the address given. lighter for recharging in transit. CIRCLE NO. 72 ON READER SERVICE CARD

ALTEC "STONEHENGE I" LOUDSPEAKER HUNNICUT DIGITAL LOGIC PROBE The Altec Corp. has introduced the The model LCA-2 Logic Circuit Analyzer, Stonehenge I medium-efficiency loud­ made by Hunnicut Digital Electronics, dis­ speaker system designed for use with am­ plays not only the logic state of a test point plifiers with a minimum 25-watt rms power be stacked above or below other compo­ but also the quality of the logic condition. capacity. The floor-standing Stonehenge I nents. Its transport system is powered by a Four lamps indicate voltage/logic levels: features a columnar bass-reflex enclosure, de servo motor, for high starting torque Good " O," Bad "O," Bad " 1," and Good a 12" high-compliance woofer with a and immunity to voltage fluctuations. "1." The LCA-2 is compatible with DTL and 9-pound magnet structure, a front­ Other featu res include separate bias and

TTL. Voltages up to 200 V ac or de, claims mounted d ividing network with equalization for ferric oxide and Cr02 tapes, the manufacturer, can be appiied to the continuously-variable, high-frequency at­ Dolby noise reduction, ferrite tape head, tenuation control, and a newly-designed LED peak-level indicators, memory re­ direct-radiator tweeter. Stonehenge I is wind, switchable level limiter and built-in handcrafted of African Afromosian Teak monitoring amplifier and headphone jack. veneers and complemented with a raw Frequency response: 40 to 13,000 Hz± 3

cocoa fabric snap-on grille, and is finished dB (Cr02 tape); wow and flutter: less than on all four sides. The system at $329, re­ 0.1% (WRMS) ; S/N: 58 dB (Doblyized). quires 1".4 square feet of floor space, and CIRCLE NO. 76 ON READER SERVICE CARD 16" x 37W ' x 14W '. Weight is 75 lbs. CIRCLE NO. 73 ON READER SERVICE CARD KOSS PHASE 2 STEREOPHONES The new Koss " Phase 2" stereo head­ CLARION AM/FM MPX/8-TRACK CAR PLAYER phones allow the listener to control the Clarion's new Model 608 8-track car stereo ambience of the program he is listening to. system incorporates an AM/FM multiplex According to the manufacturer, the listener input. The LCA-2 is supplied with a 4-foot radio. Among the Model 608 's features are can either " move himself into the center of coaxial cable, BNC connector, and three integrated .circuits, v.ertical-head tracking the orchestra" or "expand the musical input adapters. It can indicate polarity/duty to minimize cross-talk, stereo indicator sphere around himself." In either " loca­ cycle of pulse trains as high as 25 MHz. The light, stereo/mono switch, 4-watts rms per tion" he can accentuate selected portions probe measures 5112-in. long and %-in. in of the orchestra, as if he moved toward diameter. $69.50. some of the artists. The Koss Phase 2 em­ CIRCLE NO. 70 ON READER SERVICE CARD ploys Panoramic Source controls, which are thumbwheels at the lower edge of each PORTABLE FREQUENCY COUNTER earcup, and a two-position Ambience Ex­ pander. It can also be used in the conven­ The C-65A Frequency Counter by Great tional stereo mode. The medium-brown American Miniatures is a completely port­ earphones are equipped with a 10-ft coiled able unit with a frequency range of 1OHz to cord and. price is $75. 65 MHz (1 Hz to 65 MHz optional). The channel output, and a removable faceplate CIRCLE NO. 77 ON READER SERVICE CARD counter uses TTL circuitry and a 6-digit for in-dash installation. According to the LED readout. An internal nickel-cadmium company, the tape player has a frequency JOHNSON MINl-SCAN1m POCKET MONITOR power source delivers 5.volts@ 2.2 Ah . A response of 50 to 10,000 Hz, S/N of 45 dB 2.5-MHz crystal oscillator is used as a time min. and wow and flutter below 0.3% . The new Johnson " Mini-Scan" vhf scan­ base, and the unit can be used as a CIRCLE NO. 74 ON READER SERVICE CARD ning monitor weighs only 9 ounces, (255g), secondary frequency standard when calib­ while measuring 5.9" x2.6"x1 .4 ". CMOS scanning circuitry and a newly designed rated against WWV. Sensitivity is 500 mV, WHITE'S LIGHTWEIGHT METAL DETECTOR and short-term stability is 1 part in 106/24 low-drain audio section provide extended hours. Dimensions of the C-65A, costing White's Electronics announces its new battery life. The unit has a four-channel $269, are 6" x 3.5" x 2.9". Weight is 27 lightweight, solid-state metal detector, the capacity and a built-in ferrite bar antenna. ounces. Optional accessories include a Coinmaster IV-4B Series II. This refined Dual conversion and ceramic filters en­ 300-MHz prescaler, ac power supply, bat­ version of its earlier models boas~s added hance sensitivity, adjacent-channel ·rejec­ tery charger, coaxial probe, and a carrying sensitivity, which is governed by a variable tion, and good overall selectivity. The case for any or all of the above. control, a greater tuning range (both of Mini-Scan is used on the 146-174-MHz CIRCLE NO. 71 ON READER SERVICE CARD which aid searches over highly mineralized band. Other features are a squelch control, 12 POPULAR ELECTRONICS - speaker, jacks for earphone or ex­ TURNER "ULTRA-KICKER" CB ANTENNA ternal speaker, and optional flexible an­ The Turner Division of the Conrac Corp., tenna.The unit uses four AA cells and costs long a leading manufacturer of micro­ 19.95. phones for two-way radios, has introduced CIRCLE NO. 78 ON READER SERVICE CARD a line of " Signal Kicker" antennas. The " Ultra Kicker" model·shows an interesting HEATH HOME WEATHER STATION combination of beam and omnidirectional configurations. It has five elements. A A professional-type weather station, in kit center folded dipole receives power from form, is available from the Heath Company. the transmission line, and is surrounded by The ID-1290 Weather Station features a four outer vertical dipoles, which are solid-state thermometer that displays loaded through electronically switched either indoor or outdoor temperature at the stubs. The antenna can be switched to pro­ flick of a switch, a solid-state anemometer vide 8 different radiation patterns in 45-degree steps, but it remains fixed and available. Rise time of the vertical amplifier no rotator is needed. Gain is 6.2 dB over a is 35 nanoseconds, overshoot is 3% or less, half-wave dipole. VSWR is 1.5:1 , and the and the input impedance is 1 megohm front-to-side ratio is 20 dB or better. Cross­ shunted by 35 pF. The.1431 is supplied with over is 0.6 dB. Two other ·models, an om­ a handle/tilt stand, Mylar vector overlay (so nidirectional unit and a rotatable beam, are · the unit can be used as a vectorscope), but available at $79.95 and $119.95 respec­ less probe. It is $399.00. tively. Price of the " Ultra Kicker" is $239.95. CIRCLE NO. 81 ON READER SERVICE CARD CIRCLE NO. 80 ON READER SERVICE CARD with switchable ranges for 0-30 and 0-90 mph, and an electroni.c wind-d irection FANON TRANSISTORIZED MEGAPHONE indicator with individual glowing indicators & to give 16-point resolution around the B K 3" TRIGGERED SWEEP SCOPE The Fanon Model MV-5S is a combination compass. Sensing devices are mounted on Dynascan's new B&K oscilloscope, Model megaphone and warning signal in high­ a single horizontal mast that may be at­ 1431 , has a bandwidth from de to 1O MHz, impact plastic bell and housing. Rated tached to a TV mast. All connecting wires and a sensitivity of 10 mV per division. In output of the amplifier is 5 W with a 300-yd are contained in one cable. The 101290, addition to the triggered sweep, sync is range. Unit has a built-in weatherproof, housed in a simulated walnut panel, may fully automatic. A three-step vertical at­ dynamic mike, pistol-grip talk/signal be mounted vertically or horizontally and is tenuator is included, and sweep time is var­ switch , adjustable volume, and horn alarm. $89.95, less cable. iable from 0.5 µs to 0.5 s per division, in 19 Power is tu rnished by six " C" cells. $69.95. CIRCLE NO. 5 ON READER SERVICE CARD calibrated regions, and 5X magnification is CIRCLE NO. 82 ON READER SERVICE CARD

Exact now offers a laboratory-quality sweep/function generator at a price you 'd pay for less-useful sine-square oscillators. the price for And you'll get so much more out of the new Model 195 than traditional audio test moving up to a equipment, such as sine, square, triangle and swept waveforms . . . even pulses. This new 2 Hz to 200 kHz instrument is sweep/function the practical answer to many of your signal source needs, whether you 're checking audio equipment, testing bread­ generator boarded circuits or teaching at the high school or college level. just came down An internal sweep generator lets you sweep, either linearly or logarithmically, the entire audio range of amplifiers or to$149.50 speakers without changing ranges or even touching a knob. The Model 195 has three 1000:1 sweep ranges for frequency sweeping plus high and low level sine outputs with amplitude control. Or you can control the frequency by an external voltage (VCF) . The Model 195 is completely portable, operated by a 9-volt transistor battery, so you can forget 60-Hertz hum problems altogether. An optional rechargeable power supply and charger permits con­ tinuous operation from Ni-Cad battery power. This is a true instrument .. . developed by by one of the world's leading designers and manufacturers of laboratory function generators and frequency synthesizers. We accept BankAmericard Find out what the Model 195 can do on and Master Charge. your bench, and move up to a better source of signals. ••1!11111!1!1!!!1!111!1!!!1111111• ® Price: Model 195 $149.50 Optional rechargeable power supply, il!l[i][i][i]I EX~~T complete with battery and charger $25.00 l.liiiimimiiiiiil.I electronics, me. f.o.b. Hillsboro, Oregon. Instruments (A subsidiary of Dana/ab, Inc.) stocked in 36 locations across the United BOX 160, HILLSBORO, OREGON 97123 States. (503) 648-6661 TWX 910-460-8811 JANUARY 1975 CIRCLE NO. 8 ON READER SERVICE CARD 13 Read what the experts sayabout Heathkit Digital-Design Color TV

~~ The picture on the ~~ The plain truth is, with GR-2000 can only be ~~ The picture quality of service and repair costs described as superb. The the GR-2000 is flawless, soaring even for the most Black (Negative) Matrix natural tints, excellent insignificant in-home CRT, the tuner and i-f strip, definition, and pictures repair, the GR-2000 is the and the video amplifier are steady as a rock. It's way all color TV sets will provide a picture equal better than any this have to be made to that of many '' writer has ever seen.'' studio color monitors. (Family Handyman, June, 1974) in the near future ....'' (Elementary Electronics, May-June, 1974) (Popular Electronics, April, 1974) 25" (diagonal) Heathkit GR-2000 Widely reviewed and acclaimed for its outstanding picture and years-ahead engineering. At the touch of a button, the channel number appears on the screen. The optional clock module displays the time right under the channel readout. The totally solid-state varactor tuner eliminates noisy "clunkers" . with contacts that can wear out. Instead, pressing a button silently selects any of the 16 pre-programmed UHF or VHF stations. The unique fixed-filter IF never needs instrument alignment, so pictures retain unmatched clarity and brilliance year after year. And for the ultimate in convenience, add the optional wireless remote control. The GR-2000 can be custom mounted and optional cabinets start at$119.95*. Kit GR-2000, less cabinet, 147 lbs., Exp./frt...... 669.95* Kit GRA-2000-1, Digital clock module, 1 lb., mailable .. .. . 29.95* Now-a newgeneration of Heathkit small-screen color TV with digital readout

GR-500 19" (diagonal) Simulated TV pictures

Famous Heathkit quality in your choice of screen sizes -15, 17 The list of significant advances goes on and on - dual gate FET or 19" (diagonal). They all have GR-2000-inspired digital channel mixer, FET RF amplifier, 4 tuned circuits (instead of the 3 most readout and optional plug-in clock modules. "And in the tradition sets have). automatic fine tuning and preset picture control, hi-fi of the GR-2000, these TV's feature dozens of design innovations. output jack, slide out chassis. The GR-300 and 400 come com­ Each uses a precision in-line gun in the picture tube and a plete with walnut veneer cabinets, cabinets for the GR-500 start slotted shadow mask for a bright picture. The GR-400 and 500's at $39.95. negative-matrix screen provides superior contrast while lumi­ Kit GR-500, less cabinet, 88 lbs., Exp.Ifrt ...... 499.95* nance and video circuits with black level clamps maintain the true brightness of televised scenes. Kit GR-400, with cabinet, 104 lbs., Exp./frt...... 489.95* A factory-sealed static toroid yoke and magnet assembly com­ Kit GR-300, with cabinet, 90 lbs., Exp./frt...... 449.95* pletely eliminates convergence and purity adjustments - and GRA-2000·1, clock module for GR-300, 400 & 500, the picture is superior to sets requiring manual adjustments. 1 lb., mailable ...... 29.95* 14 POPULAR ELECTRONICS & unique new Heathkit products you can build yourself

Heathkit AM/FM Digital Clock Radio- The GR-1075 is no ordinary clock radio. Big, bright Beckman planar gas discharge tubes display the time. The readouts adjust their brightness automatically as room lighting changes. A standby battery power supply keeps the clock on ti me (without the display) if the electricity is inter­ stereo receiver including fixed ceramic filters in the rupted. When the power is restored, the 24-hour AM and FM circuits and a factory-assembled and alarm will be on time-and so will you. You can wake aligned FM front-end with 5 µV sensitivity. With 4 to your favorite station or a gentle electronic "beep" IC's, 41 transistors and 35 diodes, the GR-1075's de­ with adjustable volume. And the radio section uses sign is years ahead of ordinary clock radios. the same design philosophy as our famous AR-1214 Kit GR-1075, less batteries, 10 lbs., mailable, 129.95*

Digital Electronic Car Clock/Timer Desktop Electronic/Sliderule Calculator The GC-1093 is an accurate timepiece for your car, boat or At last, a sliderule calculator that's big enough to use. The IC­ plane. It's an electronic clock and a 20-hour rally timer, both 2100 has finger-sized keys and a bright, V2 "-tall 8-digit display, with quartz-crystal accuracy. Bright V2"-tall digits dim auto­ Cumulative memory and register exchanges virtually eliminate matically at night. 12 voe, scratchpad work. Performs arithmetic mounts on or under the dash. plus trig and arc trig in degrees or Kit GC-1093 radians, common and natural logs, 2 lbs., mailable powers of e, square roots, inverses, 62.95* pi and exponential functions. Kit IC-2100 4 lbs., mailable 119.95*

Dual-Trace Oscilloscope Digital Electronic Clocks A professional scope at kit-form savings. DC-15 MHz frequency with standby power response, post-deflection accelerated CRT, vertical amplifier The GC-1092A is a digital clock with a snooze alarm; the delay lines, time base up to GC-10920 reads the time in 6 digits, the month and date in :oo nsec/cm, guaranteed to 4 digits. Both have standby power supplies to keep the clock trigger up to 30 MHz (typi­ on time (without the display) even during power interruptions. cally up to 45 MHz), 1 mV I GC-1092 A & D, cm vertical sensitivity, true less batteries, 5 lbs., mailable ...... each 82.95* X-Y capability. Kit 10-4510 34 lbs., mailable 549.95*

GC-1092A Time/Alarm GC-10920 Time/Date

~TH KIT ELECTRONIC CENTERS­ -ts of Schlumberger Products Corporation 1r------­ Heath Company HEATH ~ price s slightly higher. Send for your ~ ~ UIZ.: Phoenix; CALIF.: Anaheim, El Cerrito, Los An­ 1 Dept.10·1$mrli11.l§V ~ Pomona, Redwood City, San Diego (La Mesa), FREE 1975 1 Benton Harbor, Michigan 49022 - -·- ••• :odland Hills; COLO.: Denver; CONN.: Hartford 1 D Please send my free 1975 Heathkit Catalog. : ); FLA.: Miami (Hialeah), Tampa; GA.: Atlanta; 1 • Chicago. Downers Grove ; IND .: Indianapolis; Heathkit Catalog­ : D Enclosed is$ , plus shipping. t SAS: Kansas City (Mission) ; KY.: Louisville; LA.: r. Orl eans (Kenner); MO. : Baltimore, Flockville ; the world's I Please send model(s) I IUSS...: Boston (Wellesley); MICH.: De1roil; MINN.: I I ....._apolis (Hopkins); MO.: St. Louis (Bridgeton); largest 1 Name 1 JIEB..: Omaha; N.J.: Fair Lawn; N.Y.: Buflalo (Am­ I Address I ~- New Yo rk City, Jericho (L.1.), Roc hester, White selection of I I fllliliimis; OHIO: Cincinnali (Woodlawn), Cleveland, Co­ I City State Zip I ~ Toledo; PA.: Philadelphia, Pittsburgh; R.I.: I P RI CES & SPECIFICATIONS S UBJEC T TO CHANGE W ITHOUT NOTICE CL-551 I PBaldeoce (Warwick) ; TEXAS: Dallas, Houston; VA.: electronic kits! ...... ioa(Va. Beach); WASH.: Seattle; WIS.: Milwaukee. L .:M.:11:,.0.:,0:,R ~R.:.c :: i .:~·~ _:" ~ o_:v.:______J CIRCLE NO. 5 ON READER SERVICE CARD WIJARY 1975 15 pages of design and applications informa ~ Lafayette stores or write to: Lafayette tion on the broad National line of standard Radio Electronics, Dept. PR, Box 10, Syos­ MOS products, including clocks, cal­ set, NY 11791 . culators, and memories. Complete infor­ mation can be found on National's eight­ and nine-digit calculator circuits, digital AUTHORITATIVE TIME AND FREQUENCY TEXTS clocks for desk-top, alarm and automobile A comprehensive collection of informa­ applications, shift registers-both static tion, theory, and data on time and fre­ New Literature and dynamic, semiconductor memories, quency (T/F) standards has been released including ROM 's, PROM's, and RAM's, by the National Bureau of Standards. character generators, code converters, Monograph 140, ($8.65), "Time and Fre­ ahd microprocessor' elements. Address: quency, Theory and Fundamentals," de­ METHODE ELECTRONICS PC BROCHURE National Semiconductor Corp., Marketing scribes the field of T/F research, from basic "Printed Circuits," a new brochure from Services Dept., Santa Clara, CA 95051. concepts of the measurement of time to the Methode Electronics is a 16-page descrip­ latest developments in precision timekeep­ tion of various types of printed circuitry ing based on atomic and molecular reso­ LAFAYETTE 1975 CATALOG including single-sided etched and coated nances. boards, double-sided etched and plated­ The latest edition of the Lafayette Radio Technical notes supplement the mono­ through types , additive plated-through­ Electronics catalog is now available free graph. NBS Technical Note 649 ($1 .00), hole circuits, and multi-layer and flexible upon request. It contains over 18,000 items " The Standards of Time and Frequency in boards. The brochure is well-illustrated in the consumer electronics field including the USA" is also one chapter in the mono­ with explanatory diagrams and phot.o­ stereo and 4-channel components and graph. It describes the activities of the two graphs. Methode's several multi-paneling music systems, CB, ham, and PA gear, test agencies chiefly involved in the T/F field concepts are described: " crackerboard," equipment, antennas and security devices, -the NBS and the Naval Observatory. scored-array, " nested-array," and web-ma­ musical instruments, cameras and optics, Technical Notes 616 (Revised) ($5.70) and trix panels among them. Address: Methode calculators, and many types of parts re­ 656 ($.35) deal with "Frequency Standards Electronics, 7447 W. Wilson Ave. Chicago, quired in electronic projects. The format of and Clocks: A Tutorial Introduction" and IL 60656. the publication has been changed-page " Standard Time and Frequency: Its Gener­ size has been increased 45%; larger type ation, Control, and Dissemination by the and more color have been used; audio NBS," respectively. A discussion of the 1974 NATIONAL MOS CATALOG equipment has ratings in full compliance broadcasts of radio stations WWV, WWVH, The new edition of National Semiconduc­ with the latest FTC regulations; and major WWVB, and WWVL can be found in the tors Corp.'s MOS IC catalog is now availa­ brand lines have been given expanded latter Technical Note. The publications are ble. This latest book contains over 500 coverage. The catalog may be obtained at available from the.Government Printing Of­ fice, Washington, DC 20402.

RCA LINEAR IC WALL CHART "Quick 'n Easy" C annel Scanning Available from RCA is a quick-reference wall chart giving data on their linear IC's for with <

J Pace S nning Monitors! communications, control, instrumenta­ tion, and information systems applica­ tions. Included on the chart (Form No. LIC-247A) are op amps, arrays, differential amplifiers, broadband (video) amplifiers, voltage regulators and thyristor control devices, AM/FM communications circuits, comparators, and analog multipliers. It SCAN 10-4 SERIES SCAN 150 also includes a cross-reference of direct Rubber antenna replacement types for the products of 12 shown Is optional. other manufacturers. Address: RCA Solid State Division, Box 3200, Somerville, NJ 08876.

1975 RADIO SHACK CATALOG PACE Engineers introduce the revolutionary " SCAN­ Radio Shack's 1975 catalog (No. 250) de­ MATE 150." Only4 3;4 " high, scribes the company's complete line of 2" wide and 314" thick, products for home entertainment, hob­ SCANMATE 150 scans 4 channels in a 10 MHz band byists, and experimenters. The 164-page New compact design scanner for mobile or spread within the VHF / hi / catalog has 100 full-color pages featuring base. UHF model covers 450-470 MHz, VHF FM band. The 4 internal AA Radio Shack's own Realistic stereo and model covers 144-174 MHz, LF covers 25-50 Nicad batteries can be MHz. Each of the 4 crystal channels is tune­ charged with optional four-channel receivers, automatic tu rnta­ able. Either 110 VAC or 12 VDC . Local/dis­ charger. External or rubber bles, tape recorders and players, speakers, tant function switch , lockout switches for antenna jacks provided. headphones, auto stereos and CB equip­ each channel , jack for a remote speaker, Lockout controls are pro­ power cords, mounting bracket and antenna. vided for each channel. ment. Other products included are Radio 1 All of this in an extremely compact size­ Shack electronic calculators, Archer m an­ 4Y2 " x 1Y4" x 6". tennas, and Archerkittm and Science Fair1m electronic and hobby kits. Address: Radio Shack, Dept. R-20, 2617 W. Seventh St., (cp)) ~!o:~A~!?~~~~~5~!!p~~~ue , Harbor Ci ~y·, California 90710 Export: 2200 Shames Drive, Westbury, New York 11590. Available in Canada. Fort Worth, TX. 76107. 16 CIRCLE NO. 27 ON READER SERVICE CARD POPULAR ELECTRONICS D Please send me free literature. Enclosed is$ D Ship ppd. D Ship C.O.D. Please send: Mark Ten B assem­ bled@ $64.95 ppd. Mark Ten B Kit @$49.95 ppd. (12 volt negative ground only) Stan­ dard Mark Ten assembled, @ $49.95 ppd. 6 Volt: Neg. Ground Only 12 Volt: Specify ____ Pos. Ground Neg. Ground Standard Mark Ten DeltakitE @ $34.95 ppd. (12Volt Positive or Negative Ground Only)

City/State ______----,-----,___------Zip ______CIRCLE NO. 12 ON READER SERVICE CARD alllARY 1975 17 If you've ever said... ''There 01ust be a better Send for a free Career Guidance Booklet that could start you on the road to success in a rewarding new career.

It happens to all of us, sooner or must be a way to earn enough extra later. No matter what kind of job we dollars each month to balance the have. family budget. Surely, there must be One day, it suddenly strikes home a way to get the kind of position that we're going to have to work for a where you don't have to worry about living, the rest of our lives. And most job security." of us are horrified at the thought of "Surely," in other words, "there forever being locked into the jobs we must be a better way to earn a living!" now hold. If you, too, have been thinking "Surely," we tell ourselves, "there these same thoughts, you'll find one

18 POPULAR ELECTRONICS . . ,, ~way toearn a I.1v1ng...

of our free Career Guidance Booklets Mail attached postage-free card today. If card is missing, use coupon. ,-ery helpful at this time. We invite you to send for one. ~------~------,International Correspondence Schools XA 702Q Your free booklet will describe I lcs Scranton, Pennsylvania 18515 the opportunities for higher income I Please send me a free Career Guidance Booklet, and a free "Demon· and greater job security you might ex­ I stration Lesson" for t.he field I have checked below. I understand that pect in one of the career fields listed I I am under no obligation. on the coupon and card. It will also Engineering Accounting e:x-plain why JCS can prepare you for DCivil D Business Accountant this new career field ... right in your D Mechanical D CPA Training own home ... in your spare time ... D Electrical D Income Tax Specialist regardless of your education or past D Chemical D Bookkeeping D Industrial experience. Air Conditioning/ D Surveying & Mapping Refrigeratbn/Heating In addition, you will receive a free Automotive D Air Conditioning "Demonstration Lesson" that kts you D Automotive Mechanic D Refrigeration D Heating Specialist see for yourself why preparing for a D Air Conditioning Specialist D Transmission Specialist more rewarding career-the JCS way D Interior Decorating D Body Rebuilding and Design -may be a lot easier than you think. D Diesel/ Truck Mechanic High School Please bear in mind, as you check Business Management D ICS H.S. Diploma Program off your career choice on the coupon D Executive Mgt. D H .S. Equivalency Program or card, that JCS has a long and dis­ D Industrial/Production Mgt. Drafting tinguished record of success. In fact, D Data Processing Mgt. D General I D Marketing/ Advertising Mgt. D Mechanical since 1890, more than 8,500,000 men D Architectural I and women have turned to JCS for T.V. Servicing D Color T.V. Technician MoteVHotel Management I career training. D Stereo-Hi-Fi Specialist D Motel Management D CATV-MATV Specialist D Hotel Executive I Major corporations use D Restaurant/ Club Mgt. I Electronics D Resort Management ICS Career Training D Electronics Technician I D FCC Licensing Airline/Travel JCS has provided training programs D Computer Servicing D Reservations Specialist I D Communications/ Broadcasting D Travel Agent for various divisions and branches of D Passenger Service I companies like Ford; U.S. Steel; D Electrician D Cargo Agent I Chrysler; Mobil; DuPont; etc. I JCS Career Training is approved D Check here for special information, if age 16 or under for Veterans and Servicemen under I the new G.I. Bill, and is accredited by I the Accrediting Commission of the Address------Apt.______I Xational Home Study Council. City______state_____Zip___ I Now it's your turn to discover how I JCS training can start you in a re­ Telephone ..I warding new profession. Just fill in L the coupon or the attached postpaid Approvedfor Veterans' Training. Eligible Institution under the Guaranteed Student card and mail it today for your free Loan------,Program. Accredited Member National Home Study Council. Canadian resi­ Career Guidance Booklet and free dents use Scranton, Pa. address for service from ICS Canadian, Ltd. In Hawaii: -Demonstration Lesson." 931 University Ave., Honolulu, Hawaii 96814. ©1974ICS .MmJARY 1975 21 for voice, might have a gradually de­ scending low-frequency response, and perhaps a bump in the upper mid-range. These characteristics, compensate for an emphasis of lows that most directional mikes exhibit at . close range (" proximity effect" ), and Stereo·Scene also improve articulation. Fine, but I'm usually out in the boondocks worrying about anything but proximity effects. By Ralph Hodges Now and again, I do feel a need for MIKES AND MIKING the mid-range bump (often called "presence boost" ) and wish I had it. LL RIGHT, you want to buy record.) Thus the engineer may use a But under my normal working condi­ A a good microphone so you go minimum of three microphones,-if tions (frequently my first hearing of for advice to the experts-the record­ you count the guitar's pickups-to get the music comes when the tape starts ing engineers. And a fat lot of good the sound he wants from one rolling and the performance begins), I that does you! Recording engineers musician. And today he also has the have neither the ti me nor inclination to today use not one but many micro­ option of using nonacoustic devices mess with such esoterica. (I should phones, all of which they consider that fasten on the instrument and pick mention that proximity-effect com­ " good " for a particular application. up mechanical vibrations. pensation and even presence boost For example, John Woram, a highly All of these implements can be can be cut in or out by switching on experienced studio man and profes­ brought to bear selectively, according the cases of some microphones.) So I sional consultant on recording mat­ to the way his taste tells him an in­ prefer flat frequency response, for the ters, frequently rhapsodizes on the strumentshould sound for a particular kind of recording I do. various characteristics of mikes in recording . Ultimately, recording professional sound recording maga­ studios acquire reputations for the Frequency Response. Fre­ zines. As John tells it, an engineer speciai noises they seem to be able to quency-response data for a micro­ might want to use a moving-coil mike get, or even for the sympathetic touch phone can be obtained by measur­ with a rather undistinguished high­ they give certain instruments. ing its simple electronic output with a frequency response to capture a firm, Recording studios frequently use meter. You don't have to mike a com­ slightly juicy splat from the kick drum microphones in an unorthodox fash­ plex acoustic field as you do with a (the pedal-operated bass drum in a ion. For example, now and again they speaker. But microphone and speaker drum set) , while employing a dead-flat put a mike inside the bass drum. You testing share a common problem : like condenser pickup to bring out the dry wouldn't want to do th is with one of speakers, microphones are d irec­ rustle, sting, and snap of the snare the excellent, but generally fragile rib­ tional, sometimes by accident (diffrac­ drum. In fact, a drum set, which really bon microphones of years past, be­ tion effects of the case on sound trying constitutes only one instrument in a cause the first thud hitting the dia­ to reach the diaphragm, for example) pop ensemble, may have as many as phragm would simply blow it away. and often by design. The two most three to six different microphones Few; if any, condenser mikes available common microphone directional hovering above, around , or in it. could stand the punishment without types in the amateur's inventory are And we can go on. An electric guitar distorting severely. So you take the the omnidirectional, meaning a mike or electric bass consists of the instru­ overload factor very seriously in pro­ that responds equally to sounds im­ ment itself as well as the inductive fessional recording work. pinging from all directions (or tries to, pickups below each string and the Many of these considerations are of anyway); and the cardioid, which de­ amplifier/speaker conglomeration no importance for the amateur record­ scribes a microphone that attempts to from which the sound emerges. The ist. You and I do not and never will respond fully to sounds in front of it engi neer has the choice of miking have on hand the collection of (wherever its front happens to be) and acoustically through its speaker Neumann 's , RCA's, AKG's, Senn­ not at all to sounds approaching from (which is, after all, part of the " sound " heiser's and now Sony's that the big behind it. The polar graphs in Figure 1 of the instrument), or running a direct studios can inventory. We work with illustrate these pickup patterns; im­ feed from the guitar's pickups or am­ two or three mikes at maximum, hang­ agine the circle of the omni to be a full plifier to the recording console. On ing them out in space where they're sphere, and the cardioid's pattern as a occasion he's been known to do both, not likely to get overloaded by any one ripe tomato viewed from the side. either mixing the two signals on the instrument, and we record the per­ Why would you use a directional spot or laying them dowl'l in separate formance as an ensemble effort, not microphone like a cardioid? Obvi­ tracks on the tape for subsequent mix­ as individual instruments. ously, you'd use it if you didn't like ing. And perhaps he wants to mike the For these purposes, I favor the flat­ something coming from behind. This guitar in stereo to give a greater sense test frequency response possible in a could be audience noise or room/ of the acoustic field. (Many engineers microphone. This is not the obvious concert-hall reverberation, particu­ do not, preferring to make a mono re­ choice that it first appears to be, and larly if it echoes, sounds otherwise cording of the instrument and then it's possible that many amateur record­ nasty, or is just excessive. · control its position in the stereo ists (and certainly many pros) would There are other directional types, "spread" by feeding more or less of it disagree. For example, a mike in­ too, such as the bidirectiona,I, to the left or right channel of the final tended for close-up work, especially exhibiting a figure-eight polar re- 22 POPULAR ELECTRONICS Incredible.

Sorry, but when it comes to our The Downward Expander PHASE LINEAR 4000 SPECIFICATIONS new Phase Linear 4000, modesty Gain riding, a recording technique Total Distortion: Less than .25% . 'ails us. How else would you used to improve low level signal to Typically .02% . describe a preamplifier that actually: noise on phonograph discs, Total Noise: High level: 83 dB below • Puts back in what.recording unfortunately compresses dynamic 2 volts. Phono: 72 dB below a 10 studios take out. range that would otherwise be millivolt reference. • Restores dynamics lost in available. The 4000 senses when recording to closely approximate gain riding has been used and Tone Controls: Bass : Monotonically the original. immediatelY. expands the dynamics increasing and decreasing, dual hinge • Vanishes into virtual inaudibility all points, ± 8 dB @ 20 Hz. Hinge points reciprocally downward to precisely switch selectable beginning at 40 Hz hum, noise and hiss inherent the intended level. or 150 Hz. Treble: Monotonically in most tapes, records, and increasing and decreasing, dual Inge FM broadcasts. The AutoCorrelator points, ± 8 dB @ 20 kHz. Hinge points • Lets your music (at last) reach switch selectable beginning at 2 kHz a lite-like level where cymbals The advanced Autocorrelation and 8 kHz. sound like cymbals, kettle drums Noise Reduction System in the like kettle drums. 4000 makes record/tape hiss and Active Equalizer: 6 dB/octave boost • Lets you ... for the first time . .. FM broadcast noise virtually vanish below 50 Hz. hear your music from a . .. without ettecting musical content Peak Unlimlter: (Nominal peak unlimit silent background. of the source material. Over-all noise rate attack threshold, front panel Since its in troduction follows the reduction is -10 dB from 20 Hz to variable) .5 dB/micro second for+ 6 dB Phase Linear 700 and 400 power 20 kHz. Your music comes from a peak unlimited operation. background that is silent. amps, the 4000 pre-amp had to be Downward Expander: Downward good. Consider these features: expansion commences at -35 dB. The Peak Unlimiter Plus ..• Ultimate limit is -41 dB. Unlimiter ~o prevent overload in recording .. . the 4000 is an advanced stereo window is 35 dB wide, upper and lower equipment, studios today " peak preamp with SQ• and Phase Linear thresholds are simultaneously variable. limit" high-level explosive transients differential logic ... its Active Auto Correlator (Noise Reduction of the source material. Incorporated Equalizer gives you a truly flat energy Systems): High frequency noise reduc­ 1n the Phase Linear 4000 is a distribution over the full audio tion commences at 2 kHz and is 3 dB, ighly-advanced circuit that reads. spectrum ... completely passive, reaching 10 dB from 4 kHz to 20 kHz. oeak limiting, immediately routes independent, Step-Tone Controls We ighted overall noise reduction is he signal through a lead network, allow precise tailoring of the music -10 dB from 20 Hz to 20 kHz. and restores dynamics lost in to your listening environment. Size: 19" x 7" x 10"-Welght: 18 lbs. ·ecording to closely approximate It is, in a word, incredible. Ask your • e original. dealer for an audition. Warranty: Three years, parts and labor.

f/JltaM3~ 4000 THE POWERFUL DIFFERENCE

is a 1rademark or CBS Labs. Inc. PHASE LINEAR CORPORATION, P.O. BOX 1335, LYNNWOOD. WASHINGTON 98036 CIRCLE NO. 28 ON READER SERVICE CARD quencies, you could draw Fig. 3 di­ and ranged from dismal to marginal rectly from it. (moving coil), better (ribbon), and best What does all this mean? Well, as (condenser). Improved materials and you may know, the frequency re­ construction have made remarkable Fig. 1. Mike pickup patterns: (left) sponse you hear from a speaker in a strides in narrowing the gap, so that ominidirectional; (right) cardioid. room is a combination of its numerous on a dollar-for-dollar basis you can sponse (or, to continue the three­ frequency responses at various an­ get perfectly acceptable-if not dimensional analogies, a crudely gles, since reflections from room identical-results from any. Of course, formed dumbbell with no place to boundaries ultimately bring to your ribbon mikes are complex in construc­ grab onto), and thesupercardioid and ears the speaker's output at 60 de­ tion and not really available below hypercardioid varieties, which narrow grees, 90 degrees, 180 degrees, etc. $100 apiece. But ;;it around $150 you the cardioid 's tomato down into a And the frequency response of a mi­ might well pick a ribbon over moving pepper {sometimes even a chili pep­ crophone {i.e., what it " hears") is also coil or a condenser. per) shape, usually with some leafy a composite of its various responses Then there is the question of rug­ growth at the stem indicating l~ss than at all angles, since it's picking up the gedness and resistance to acoustic total success in eliminating rearward same sort of room reflections. overload. To my knowledge I've never sounds. Some of these are beloved by It follows (or so it seems to me) that had a mike physically overload, but professionals, either for their pickup the real frequency response of a mi­ then I don't work close up as a rule. If patterns or for other special qualities. crophone is not the simple on-axis you plan to, then you should know that But they are rarely part of the curve, but some kind of summation of moving-coil types are considered best amateur's equipage. the curves in Fig. 3 and many others at shrugging off the very high sound­ Back to frequency response. The besides, all adjusted for the reflectivity pressure levels that come from brass, sound-output pattern of a loud­ of the particular recording environ­ drums, electronic instruments, etc. speaker can also be shown with polar ment. But since you can't predict the plots. But as any casual audiophile nature of the recording environment, knows, the polar pattern wi II not be the you're ultimately best off, I'd imagine, same at all frequencies. Lows tend to with a mike whose response changes ~ o• become omnidirectional, while highs little with incident angle. The mi­ .. , -1 ..z - may begin to "beam" in a tight super­ crophone of Figs. 2 and 3 is not too 0 90° Ir. ,\ bad in this respect. Others will be bet­ ~ v, -...... J \' t"' II" \1,,1 ~ J ter still, and some will be worse. And 5d8 180° for some microphones you may be in­ T - terested in, the relevant data of this 20 50 100 500 IK SK IOK 2 FREQUENCY (Hz) kind will prove difficult to get, I'm Fig. 3. Cardioidfrequency response afraid, even from the manufacturer. on axis and at two angles off-axis. But we all do our best. Some condenser jobs come fairly Microphone Types. There are close, but few condensers can always 27o•t-1-++-+---+---+--+---1~+---+--+---+--7-+--+-i ~0 • only three microphone types that in­ be trusted in these applications. Rib­ terest the serious recordist: moving bons used to have a terrible reputation coil, ribbon, and condenser. The mov­ for going mechanically to pieces at the ing coil closely resembles a speaker slightest provocation, and sometimes (and especially a dome-type tweeter) suffering permanent injury. Many of in construction. In operation its cone the breed are still quite delicate, but (or dome) is shuttled to and fro by im­ Beyer claims that its ribbons can tol­ pinging sound, and the magnet as­ erate sound-pressure levels in excess

SCALE IS 5 DECIBELS PER DIVISION sembly induces an output voltage in of 130 dB-well into the moving-coil A' 5 kHz the coil that moves with it. The ribbon class; and the Group 128 condenser B• I kHz type employs a low-mass diaphragm C' 500Hz mikes are said to be equally rugged. D• IOOHz of corrugated metal foil that is also the As for directional properties, mov­ inductor as it moves within a magnetic ing-coi I and condenser mikes can be Pig. 2. Cardioid pickup patterns field. Condenser microphones consist made to exhipit practically any pickup at four different frequencies. of a light diaphragm in close proximity pattern. The same is theoretically true to a conductive plate. The diaphragm for ribbons, but I don't know of any cardioid fashion. So it is with mi­ is polarized-either by an external de omnidirectional ribbon mikes. crophones, although their directional voltage source or with a built-in (elec­ Incidentally, lest I have frighten~d aberrations are not always the same. tret) electrostatic charge-and as it anyone away with my brief reference Figure 2 shows the polar plots for a moves relative to the stationary plate to prices above, let me say that fine cardioid mike at several different fre­ in response to air-pressure changes, moving-coil and electret-condenser quencies, while Fig. 3 gives its various the varying capacitance modulates mikes can be had for $50 and less. frequency responses for sounds the. output voltage. originating at zero degrees (right in The time was when the high­ Impedance, Sensitivity, Etc. front, or "on axis"), and at several an­ frequency responses of these three These topics frequently form the bulk gles off axis. If the polar plot of Fig . 2 types were a function of their dia­ of microphone how-to-buy articles. I showed the pickup patterns for all fre­ phragms' inherent moving mass~s. plan to give them .very short shrift. 24 POPULAR ELECTRONICS

HIGHLIGHTS ' .

Phillps & MCA Market Video Disc sensor is placep over the dot, and decodes the informa­ ! . ' . tion which can be printed, displayed, or recorded by a N. V. Philips, based in the N~therlands, and MCA, variety of terminal devices. The manufacturer says that Inc., Los Angeles, have reached an agree:rpent for mar­ modules caq be used without any mpdifi.cation of the keting a Philips/MCA video-disc player and compatible TV receiver. This .system has many possible uses. It can discs for consumer use. An official of MCA states that provide data to accompany any televised event-per­ this development will result in the interchangeability of formance ~ecords of a player involved in a sports com­ their Video discs. The companies Will establish a licens­ petition, historical information on dramatic characters, ing organization to negotiate with others for related pat­ even stock market and news reports! ents. It is expected that a liberal licensing po).icy will enable many companies to participate in the viqeo player technologies of both concerns. The Philips/MCA "Under New Proprietorship" video ~ disc player will be manufactured and mark~ted by Philips, while MCA, whose resources µtclude the Uni­ GTE Sylvania and Philco-Ford jointly announced an versal Pictures film library, will produce and market agreement under which the former would acquire the video disc programs. · Philco name and distribution rights for home enter­ tainment products manufactured by Philco-Ford's Home Products Division, and sold in the U.S. and Blank Tape Sales Skyrocketing Canada. The agreement does not involve Philco-Ford's line of home refrigerators and freezers, its Telesound Nearly 200 million blank cassette tapes and 30 mil­ oper.ations, or its automotive products. In another de­ lion · blank 8-track cartridges will be ·purchased thls velopment, North American Philips Corp. acqu~red year, according to the Longines Symphonette Com­ about 85 per~ent, or 15 million shares, of the outstand­ pany, a major producer of such tapes. · The company ing stock in the Magnavox Company. also states that cassettes, tnough now considered a hi-fi medium; are being used for speech recording as well as music. Students are recording their lectures, and Trends in the Microwave Industry businessmen are taping their confer!')nces on cassettes. The microwave products indu~try represents 8 per­ These new demands, according to a Longines sales pro­ cent of the total electronics industry, and generates jection, will push the total cassette purchases in 1976 to $2.2 billion annually in economic activity. This figure is top 340 million. This represents an increase in sales at expected to grow to $2.8 billion by 1983, according fo a the rate of 50 million more new cfssettes per year. report assembled by the Business Communications Company, Stamford, Conn. A large (7.5 percent) an­ nual growth is predicted for the microwave oven field. · RCA Introduces Hybrid OP Amps RCA's Solid State division has introduced a family of Private-Use TV Station hybrid op amps that combine the advantages of MOS/FET's, bipolar transistors, and COS/MOS on a A new television station, available for private use, has monplit)'lic chip. Gate-protected PMOS transistors are opened in New York City. It is part of a new service used in the input circuits of the CA:513D family, to pro­ authorized by the FCC, called Multip'oint Distribution vide.very high input imped;:i.nce, low input current, and Service. The new medium, named "Private Television," high-speed performance. The common-mode input­ is to be utilized by business, government, and enter­ voltage range goes to 0.5 volts below the negative­ ti}inment users to deliver their programs at lower cost supply terminal. A bipolar driver provides voltage gain. than is possible via other available means. . . . Owned A COS/MOS drain-loaded inverting amplifier comprises and operated by the Microband Corp. of America, the the. output stage operating in the Class A mode. The station has its control center located in the Empire State output can be swung within !'Ilillivolts of either supply Building and will provide its full-color private TV rail when used with highly resistive loads, and the gain transmission facilities to various locations throughout of this stage depends on the load impedance. Open loop the tri~state area. . . . The station comes under FCC gain of the op amp is 110 dB and bandwidth is 15 MHz. common-carrier regulations, which restrict its activity The CA3130 series can be used as comparators to program distribution only. · Customers select the (COS/MOS interface), wideband amplifiers, voltage transmission time, as well as the individual receiving regulators and followers, and in timing applications. points, and control the program content. Multiple Dis­ tribution Service (MDS) uses microwave frequencies (2150 MHz) and a system of address-encoding to as­ Data Transmission on Real-Time TV sure program privacy ... . Microband is affiliated with A new system of encoding information on broadcast MDS stations in other cities through a national system TV signals has been introduced by the Atlantic Re­ that plans to use domestic communication sattelites to search Corp., Alexandria, Va. The Data-Dottm system interconnect them in a national private TV network. modifies the video signals to cause asmall dot to appear Stations are presently in Washington, D.C., Chicago, in a corner of the receiver's screen, which carries one or Houston, Baltimore, and Philadelphia. Coverage for more channels. of information. A peanut-sized optical Miami is expected soon.

26 PQPULAR ELECTRONICS DISPLAY: LED Matrix: 4x16 LED Matrix. 4 chan­ MODES: Normal: for most troubleshooting and nels: with 16 divisions per channel useful for deter­ testing applications. Storage: on all 4 channels mining extensive time relationships. stores the information In a 16x4 bit high speed RAM TIME BASE: Range: from .5 u sec. to .2 sec. and displays the signal continuously. Triggering: from channel one Input signal; positive PULSE CATCHING: Single-shot storage or negative edge selection using SYNC switch; also capability: can catch and store a one-time occurlng an automatic sweep for checkfng DC steady-state pulse In the memory and display It for as long as signals. desired. Range Selection: using three controls-a poten­ POWER: Battery: operation using rechargable tiometer for Initial sweep rate and two switches for NICads. AC: operation using an AC-(Adap­ X1000 and X20 selection. ter/Charger) for use with normal 11 O v .a.c. OR, IF YOU REALLY WANT TO * PRICE: MS-416 (fully assembled) ...... $189.50 SAVE, BUILD YOUR OWN MS-416 (kit with easy-to-follow manual) ....$127.50 MS-416 FOR JUST $127.50

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28 JANUARY 1975 er. etrain 1ou on two TV's nstead of one keep both)

With Sylvania's Master TV Career Pro­ need to make it in the world of gram, you get not just one but two TV electronics. sets. Color and Black & White. Both Throughout your training, solid-state. Both designed to give you Sylvania makes that extra effort to go the solid, practical experience you one better. need. Both yours to build, learn with Send the card or mail in cou­ and keep. pon today for our FREE Catalog. And With all Sylvania Career Pro­ go with Sylvania. grams you get our exclusive Autotext r------, method of instruction, a modern, SYWANIATechnical Schools Home Study Di vision 694-501-0 step-by-step approach to learning, Sylvania Technical Systems, Inc. which gets you through the basics of 909 Third Avenue electronics quickly and easily. New York, N.Y. 10022 An optional Cassette System, a Please send me FREE illustrated ca reer catalog. I understand that I am under no technique that adds an extra dimension obligation. to learning. It's almost like having an Name ______~ instructor right in your own home. As you play the tapes, he'll guide you through your lessons, explaining as Address ______you read , going over schematics and reinforcing everything you learn' City ______Plus a choice of Programs that can lead to any numberofcareergoals. State ______Zip __ In TV, communications, automation, I digital and solid-state electronics. And Age I in fields you haven't even dreamed of. Veterans: Check here o I Plus specialized advanced train­ L------J ing and carefully-engineered Project Kits for that "hands-on" training you [?ii~ SYLVANIA

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* DISPLAYS UP TO 16 LINES (of 32 Ch aracters) AT ONE TIME. * 1,024 Ch aracter - Two Page Memory Capac ity - STANDARD. * Plug-In Circuits to adapt the terminal to any requirement at lowest possible cost. • Requires +5 Volts DC@ 2.5 Amps, ·5 and -12 Volts@ 20 Ma. * Use with any TV set

• Up to date, low power consumption STATIC type MOS Memory. • No compl icated refresh or power-down circuits needed.

At last we can tell you about the most versatile, video· allows either the keyboard, or the computer to access the display terminal kit available anywhere; the Southwest terminals memory and display data on the sc reen. Technical CT-1024. Our t erminal is designed around a basic mother board and a 6, 144 bit memory that will display For those applications where it is useful, we also have an two pages of data on any standard television set, or moni· "off line edit", or "screen read" plug-in circuit #CT-E. tor. The two pages consist of 16 lines with 32 characters on This allows you to compose a program, or message on the each line. Input may be any source of parallel ASCII code; terminals display screen and transmit it out a line at a time keyboard, computer, etc. If the system is to be used for a when you are finished and satisfied that everything is cor· display, teaching aid, deaf communicator, or other si milar rect. purpose; this is all you will need. If you would like the convenience of complete cursor con· Other applications of a terminal system such as remote time trol, we have our #CT-CM plug-in board. This gives you share, RTTY, etc require an interface having a serial output. Move Right, Move Left, Move Up, Move Down, Home Up, For these applications you ad d our# CT-S plug-in UART Era se to end of line and Era se to end of frame functions. card to the mother board . This allows you to transmit and These are operated by keyswitches, or any other type receive ACSCll coded data in serial form at a rate of 110 switches you may wish to use, giving you complete manual baud. (300 and 600 baud options are available). The control of the cursor. standard RS -232 type interface connects directly to your transmitter FSK modulator, modem system, or what have If the term in al is to be part of a computer system, you you. might prefer our automatic cursor control circuit # CT-CA. This plug-in not only allows you to control the cursor and If you are going to use the CT· 1024 directly with a com· to perform the functions listed above, but makes possible puter 1/0 port that requires a parallel ACSCI I input, then computer control of t hese same functions t hrough the you will want our parallel interface card, #CT-P which machines software.

# CT-1024 Terminal System Kit with 1024 Memory Card- less cabinet or power supply ...... $175.00 PPd # CT-E Screen Read Plug-in Card Kit...... $ 17.50 PPd # CT-M Manual Cursor Control Plug-in Card Kit ...... •...... $ 11 .50 PPd # CT-P Power Supply for CT-1024- 115-230 Volt Primaries...... $ 15.50 PPd # KBD-2 Keyboard Kit - 53 Keys ...... $ 39.95 PPd FREE-1975 Catalog-Circle our number on the "Bingo" card.

SOUTHWEST TECHNICAL PRODUCTS CORPORATION

219 W. RHAPSODY

SAN ANTONIO, TEXAS 78216 CIRCLE NO. 34 ON READER SERVICE CARO 32 POPULAR ELECTRONICS Popular Electronics JANUARY, 1975

EXC:LUSIVEI ALTAIR 8800 The most powerful minicomputer project ever presented-can be built for under $400

------~- ---=----=------~-- ­ ALTAIR aaaa • • • • • .J • • • .. • • ...... -• • - • - - -­ - - ­- ­ - -

BY H. EDWARD ROBERTS AND WILLIAM YATES

HE era of the computer in every tral processing unit is a new LSI chip T home- a favorite topic among that is many times more powerful than science-fiction writers- has arrived! previous IC processors. It can ac­ PROCESSOR DESCRI PTION It's made possible by the POPULAR commodate 256 inputs and 256 out­ Processor: 8 bit parallel ELECTRONICS/MITS Altair 8800, a full­ puts, all directly addressable. and has Max. memory: 65.000 words (all directly blown computer that can hold its own 78 basic machine instructions (as addressable) against sophisticated minicomputers compared with 40 in the usual Instruction cycle time: 2 µs (min.) now on the market. And it doesn't cost minicomputer). This means that you Inputs and outputs: 256 (all directly ad­ dressable) several thousand dollars. In fact, it's can write an extensive and detailed Number of basic machine instructions: in a color TV-receiver's price class program. The basic computer has 78 (181 with variants) -under $400 for a complete kit. 256 words of memory, but it can be Add/substract time: 2 µs The Altair 8800 is not a " demon­ economically expanded for 65,000 Number of subroutine levels: 65,000 strator" or souped-up calculator. It is words. Thus, with full expansion, up to Interrupt structure: 8 hardwire vectored the most powerful computer ever pre­ 65,000 subroutines can all be going at levels plus software levels sented as a construction project in any the same time. Number of auxiliary registers: 8 plus electronics magazine. In many ways, it The basic computer is a complete stack pointer, program counter and represents a revolutionary develop­ system. The program can be entered accumulator Memory type: semiconductor (dynamic ment in electronic design and think­ via switches located on the front or static RAM , ROM . PROM) ing. panel, providing a LED readout in bi­ Memory access time: 850 ns static RAM ; The Altair 8800 is a parallel 8-bit nary format. The very-low-cost termi­ 420 or 150 ns dynamic Ram word/16-bit address computer with an naI presented in POPULAR ELEC­ instruction cycle time of 2 µs. Its cen­ TRONICS last month can also be used . JANUARY 1975 33 matter) is shown in Fig . 1. It consists of the following subsystems: PARTS LIST CPU. The heart of the computer is the CPU , or central processor unit. See fig. 2. The CPU performs all the calculations, generates system tim­ Cl, CS to ClJ--0.1-µF disc capacitor ing, and makes all decisions. Of par­ C2--0.0J-µF disc capacitor ticular importance are the decisions C3, C4-JOO-pF disc capacitor the CPU makes concerning what de­ Cl4 to C20--0.00l-µF disc capacitor vice should have access to the data ICl-8080 central processing unit IC (Intel) buss. It makes these decisions by IC2toIC5-74L741C sending status information at the be­ IC6 to IC14-8T97 IC Fig. 1. Basic block ginning of each computer cycle, tel­ diagram of computer ICJS, IC17-7402 IC parts and operation. ling the memory and the input/output IC16, IC32 , IC33-7404 IC what to expect for the rest of the cycle. ICJB to IC20, ICSl-74123 lC The CPU contains the program 1C21-7473 JC timer, sometimes called the P counter. IC22 to IC24, IC50-7400 IC This device keeps track of the current IC25-7430 lC In an upcoming issue, we will de­ location in the memory that the proc­ IC26-74l0 LC scribe how to build a low-cost CRT­ essor is using. Also located in the CPU LC27 to IC3l , IC39 to IC41-7405 LC type terminal that can be used with the is the arithmetic unit. IC34, IC35-81 l l IC IC36-74L30 LC The CPU used in the 8800 computer, computer and can also be mated with IC42 to IC49-74LOO re any time-sharing computer by tele­ the Intel 8080 LSI chip, is relatively ex­ IC52-7406 IC phone. pensive in quantities of one. It was IC53 to IC58-81 l l LC (optional) selected, however, because it serves LEDi to LFD36-Panel-type, red light­ About the Computer. A computer is to create a minicomputer whose per­ emitting diode basically a piece of variable hardware. formance competes with current (Note: Following are resistors Y2-watt, By changing the bit pattern stored in commercial minicomputers. In prac­ 10% tolerance) the memory, the hardware (electronic tice, a lower-performance processor RI, R3, R9to R31, R56-1000ohm circuitry) can be altered from one type would have been adequate for the ma­ R2, R4, R7, RS-330 ohm R5, R33 to R37-2200 ohm of device to another. When the bit pat­ jority of the tasks the user might wish R6-7500 ohm tern , and thus the hardware, is to initially define. But the problem with R32-100ohm changed, we have what is referred to the lesser-power approach is that rela­ R38, R48 to R55-10,000 ob.m as " software." Any type of variable in­ tively little money would be saved, and R39-200,000 ohm struction (programming)-such as it would be doomed to near-future ob­ R40 to R47-470 ohm Basic, Fortran, Cobol , Algol-is gen­ solescence for practical purposes. R57 to R92-220 ohm erally classified as software. Our intent here was to produce a SI to SJ6, S25-Spst miniature toggle To cause it to vary the hardware, you processor with more than enough switch must communicate with the compu­ power to handle any job. Sl7 to ~Spdt spring-loaded, momen­ ter. In the case of the 8800, this is done Still another consideration was tary-action miniature toggle switch XTAL-2-MHz crystal by setting the bit pattern on the front­ programming. The larger the instruc­ Misc.-Metal case; power supply (see panel switches in accordance with a tion set, the easier the computer is to text); line cord; multiconductor ribbon set of instructions (provided with the program. The 8080 chip has 78 in­ cable; mounting hardware; solder; etc. Intel 8080 LSI chip). For example, the structions, which is almost twice that Note: The following items are available 8800 computer will automatically add of the next power level CPU available from MlTS, Inc., 6328 Linn N .E., when a specific bit pattern (10000010) (Intel's 8008), wh ich is really designed Albuquerque, NM 87108 (Tel.: 50.S­ is received. By setting address and for use as a buffer. 265-7553): partial kit No. 8800PK (in­ data switches, a complete program of The CPU contains eight general­ cludes pc boards and all electronic com­ up to 78 steps in the basic computer purpose registers, P counter, arithme­ ponents (but not case, switches, or can be inserted into the processor. If tic unit, accumulator, stack pointer, power supply), $298; complete kit No. 8800K (contains all parts, including extensive programming is to be per­ instruction decoder, and miscellane­ ready-to-use case, switches, and power formed , an assembler or higher lan­ ous timing and control circuits. The supply), $397; Completely assembled guage is used. With an assembler, the arithmetic unit is of special interest and tested Model 8800A computer (in­ person doing the program simply because it contains the circuitry re­ cludes 90-day warranty), $498. Prices do types the word " add" on the device. quired to perform arithmetic in both not include postage or delivery charge. (In Basic and Fortran, a + is used in­ decimal and binary formats. Both kits include detailed assembly and stead.) The stack pointer is the register that operating manual. A FREE set of etch­ Fundamental programming con­ keeps track of the subroutine ad­ ing and drilling guides, component­ cepts are simple enough to master in a dresses. The 8800 computer is capa­ placement diagrams and miscellaneous relatively short time. However, to be­ ble of performing an almost unlimited informaticn is available from the kit sup­ plier (send self-addressed 8Y2" x 11" en­ come an efficient programmer re­ number of subroutines, a feature not velope with 40c postage). Check sup­ quires a lot of experience and a large available with other microprocessors plier or manufacturer for latest ICI amount of creativity. and absent in many minicomputers. price, available separately. The block diagram of the basic 8800 The instruction decoder is the core computer (or any computer, for that of the variable-hardware concept. It 34 POPULAR ELECTRONICS j.I! t ? • t t t

..:~t e9-. H IS .,.- ~·-= ~r "1JT ' ' 1~i l Os- READ/WRIT£ TIMING ANO ANO MULTIPLEXER l~~'if'· CONTROL ; I - ,. TEMPORARY RE81STER DECIMAL Ill .,., ARITHMETIC !! Z 1a1 I !ii •-4 RE81STER !: :s a ,...._ ,. L I H ACCUMULATOR "' (8) E 0 11 •Ill I ~f I ,.. c I n • f-::::i "' STACK POINTER - -4 • PRO&RAM COUNTER ' INSTRUCTION READ/WRIT£ t- ~ DECODE ANO CONTROL ir ACCUMULATOR ~· - LATCH (8) ' INCREllENTER OECREMENTER - t ALU INSTRUCTION (8) RE81STER

ADDRESS LATCH I (IS) --- •

• TEMPORARY I FLAG (S)I REGISTER 110 BUFFER (8) - ADDRESS DRIVERS ANO LATCH CUil j ' j

I I ,, I . ) I ' J ' I I ) •) ' ' ~ ' ' Al5 Al4 AIS Al2 All MO A9 A8 A? A•8 M A4 Al•• M. A l Af• 01 oe os 04 01 02 01 of '. +5V Fig . 3. The logic associated with the CPU ([Cl) is shown A i,~1------~ ;------A ,,~ at left. All of the buffers · IC6-Ice j and latches are on a single > I Al5 Al5 pc board. Connecting wfring ------ADDR DS8L is thraugh a 100-line biiss.

D~l------..,.....~~------DO~ : ! ~ ob1 ------DO DSBL ICI 8080 decodes the instructions and sets up the various registers, gates, etc ., in the CPU for proper functioning. All system timing comes from the CPU . (The logic associated with the CPU is shown in Fig. 3, while the system clock is shown in Fig . 4.) Memory. A computer memory stores the various binary O's and 1 's that make up its language. These O's and 1 's are known as bits. Some memories are organized to store 4, 16, 24 , or 32 bits to a word , while others-specifically those in the 8800 computer- are organized to store eight bits to a word. Each time the CPU requests data from the memory, a complete word is transmitted. The • 1------4 >------PSYN C term byte is interchangeable wi th the 1------1 ;------PDBIN

1------1 ~------PWA IT 1------~)------P"WR 1------1 ~------PHLDA 1------1 )------PINTE

READYI------<. 1------RDY HOLD HOLD Printed circuit boards are INT IN T designed so that the various RESET RESET mating pads are aligned.

~ ICl2-IC14 Multi-conductor 1ibbon cable interconnects the boards.

36 POPULAR ELECTRONICS term word in an 8-bit processor. (The basic 8800 memory is shown in Fig 5.) The time required from when the ir-+-----t~- +5V address first appears until the data is RI R3 stable is called "access time." In most modern semiconductor-memory minicomputers, it ranges from 15 ns to Cl 30 µs. With proper adjustments, any R2 R4 XTAL I +sv memory speed can be used in the8800 ...__-~o computer, although standard memory time is 850 ns for a static random­ R& access memory (RAM) and 420 ns for a R6 dynamic RAM . Higher-speed memo­ ries will not appreciably affect 2 the performance of the computer, while slower-speed memories will re­ <1>2-...,--. sult in an overall reduction in system Tl--:--...... I------~--­ speed . .,,, In addition to semiconductor RAM 's, the processor will also service ROM 's (read-only-memories) and Fi.g. 4. Computer operation is controlled by PROM 's (programmable read-only signals from thi8 2-MHz clock circuit. memories). Access time should be reinforced for the particular memory used. standard low-power load per expan­ rent instruction. An automatic stop Any conventional memory can be sion card . occurs when power is turned on (in­ used in the computer if the input load­ terrupts are disabled). ing on the buss does not exceed 50 Front Panel. The front-panel logic 2. RUN : Starts the processor at the TTL loads and if the buss is driven by permits the following functions: current address. standard TTL loads. Normal expan­ 1. STOP: Stops the processor im­ 3. EXAMINE: Causes the data stored sion loads to the buss would be one mediately after it completes the cur­ at the location (set by the switches) to

IIC41 I l>)Cl•---ROY IC48, IC4!:_IC38, IC41 p~~~~~I ...+------....,_-;:::::.:... IC47 PROTECT STATUS .,,, I PROT------;-----' UNPROT------....:_____,...... , A,o------­ ~7---...... ---.--­ or"' ' IC34, IC35, . IC53,IC&8, '--.---001

IC45, IC46 IC40,IC41 ~ A8 --"'~---;. OI O

Oi i A9

OI 2 o:n "CE20 OI4 Ar~ OIS Ci1 OI6 OI7 AJSt I Rl7- R24 +sv MEMR----~0 ------~-1------_,

Fi.g. 5. The basic memory contains u p to ei.ght 256 x 4 RAM's.

JANUARY 1975 37 be displayed in binary by LED 's. are in various stages of design or un­ various mating pads on both are 4. EXAMINE NEXT : Steps the p dergoing tests] aligned. Multi-conductor flexible rib­ counter once and displays the word bon cable Interconnects the boards. stored at the next location. Assembly Details. The basic com­ The front panel control board con­ 5. DEPOSIT: Causes the information puter employs four printed circuit tains the circuitry for the interfacing preset by the switches to be stored in board assemblies, each of which con­ between the control switches located the memory. tains one functional element of the on the front panel and the CPU . In ad­ 6. DEPOSIT NEXT: Stops .the p basic system. Because the boards are dition to the interconnections ·to the counter and loads the memory. large and very complex, we are not actual processor, this board accepts 7. SINGLE STEP : Steps the program publishing etching and drilling guides memory address switches AO through one instruction. or component-placement diagrams. A15 (also on the front panel). The first 8. RESET: Clears the CPU and sets Instead, you can obtain a set of guides, eight of these switches (DO to D7) are up a starting address of 0. diagrams, an Instruction set, buss used to put data into the CPU . The 9. CLEAR EXT: Clears all input/ out­ points, and miscellaneous informa­ EXAMINE/ EXAMINE NEXT, DEPOSIT/ put devices; occurs automatically tion by sending a stamped self­ DEPOSIT NEXT, SINGLE STEP, and RUN/ when power is turned on. addressed 8Y2'' x 11" manila envelope STOP switches are also wired directly 10. PROTECT/ UN PROTECT: Allows with 40c postage to MITS, Inc. (See to the front panel control board. selective protection/unprotectlon of note below Parts List for address.) Re­ The third board contains the Intel blocks of memory. When a block of quest the PE8800 package. 8080 central processing unit LSI chip, memory is protected , it Is Impossible The front panel display board ac­ two-phase clock and buffers, and the to write over that block, but Its con­ commodates the 36 LED indicators various lines going to the buss. (The tents can be read out. and their associated drivers. Address buffers are tri-state, high-input­ There are 36 LED status indicators line Inputs AO through A16, data lines impedance, high-output-level de­ on the front panel, 16 of which are DO through D7 , and the various status vices.) This board also has four dual-D used for the address buss, 8 for the lines originate on the CPU board. The flip-flops wired as latches for the eight system status latches, and 8 for the boards have been designed so that the bits of status Information. All Input data buss. The four remaining LED's and output wiring to and from the CPU are used for indicating memory­ board is via a 100-line buss. protect, interrupt, system-wait, and SM APPLICATIOllS FOR TIE The basic memory board contains hold status. ALTAIR ... COMPUTER 256 eight-bit words of random access Power Supply. Four power Listed below la only a small aampllng of memory (RAM) . It is directly expand­ sources are required to operate the the thousands of poaalble appllcatlona able to 1000 words. This board also computer: + 5 volts at 2 amperes, -5 for the computer. The Altalr 8800 la so contains the input/output data-gating, volts at 500 mA, - 12 volts at 500 mA, powerful, In fact, that many of these ap­ address-decoding , memory-wait, and and + 8 volts at 6 amperes. The first pllcatlona can be performed simultane­ memory-protect circuits. The mem­ ously. It can be used as a: three are regulated , while the last is ory-wait circuit allows the mem­ • Programmable scientific calculator unregulated . Thethree regulated lines • Multichannel data acquisition sys­ ory time to stabilize the output data to power the processor. The unregulated tem the processor, while the memory­ line powers the peripheral cards that • Automatic control for ham station protect circuit prevents accidental can be used to expand the system , • Sophisticated Intrusion alarm sys­ overwriting of the memory. All con­ each of which has its own 5-volt reg­ tem with multiple combination nections between the CPU and the ulator on board. This reduces electri­ locks memory board are via the 100-line cal noise and obviates the possibility • Automatic IC tester buss. of total system failure due to the fail­ • Machine controller The four boards, along with the ure of only one regulator. • Digital clock with all time-zone con­ power supply, mount in an 18-in. deep version Expansion. The basic computer is by 17-in. wide by 7-in. high (45.7 x 43.2 • High-speed 1/0 device for large designed for almost unlimited computer x 17.7-cm) metal cabinet. The various peripheral and memory expansion, • Digital signal generator operating switches and LED indi­ using a buss system where all • Automated automobile test an­ cators go on the front panel. When all input/output connections merge into alyzer this is done, the computer cabinet's a common line. Hence, an external • On-board mobile controller interior will appear to be almost card can be plugged into any slot and • Autopilot for planes, boats, etc. empty. However, the internal cabling it will function properly. The only qual­ • Navigation computer system is arranged with connectors to ification is that each card have an ad­ • Time-share computer system accommodate 17 more boards within dress decoder to allow the specific • "Smart" computer terminal the case, all connected to the main • Brain for a robot card to take what data it needs from buss lines. The added boards can be • Pattern-recognition device the common buss and put data on the • Printed matter-to-Braille converter used for memory, input/output de­ buss as required. The processor buff­ for the blind vices, control devices, etc. All you ers are designed to drive 300 external • Automatic drafting machine have to do is plug the boards into the cards, which should be adequate for • Automatic controller for heat, air connectors and the computer does most applications. Bear in mind that conditioning, dehumidifying the rest. only 17 cards will yield 65,000words of • Controller for sound systems Part 2 of this article, next month, will memory. • Digital filter describe the operation of the com­ [Editor's Note: At this writing, a • Signal analyzer puter and present some sample number of different peripheral devices programs. ~ 38 POPULAR ELECTRONICS HE ELECTRONIC flash system BY MICHELE FRANK T brought " stop action" photo op­ pertunities to camera enthusiasts. It also eliminated the need tor changing spent \\ashbu\bs \han\<.s to the stor­ age properties of the electrolytic capacitor and the use of long-life · gaseous lamps. The next major ad­ vance in electronic flash technology can be pinpointed to 1965 when Hon­ eywell Photographic introduced an automatic electronic flash, freeing photobuffs from having to set f-stops for each shot that was at a different distance. Now electronics has created another plateau in automatic flash technology by adding thyristor control-an SCR that both triggers the flash and stops capacitor dis­ charge when the subject receives suf­ ficient light. The result? More flashes per battery charge, faster recycling time for the next shot, and short re­ charge time.

~ Flash of Light. For background, here are the various steps that go into producing the electronic flash of light. First, voltage from a battery, the usual power source in an electronic flash, is converted to ac by means of an oscillator circuit. (This oscillator, by the way, is what causes the charac­ teristic " whine " you hear in the elec­ tronic flash unit.) Once the ac is gen­ erated, it is stepped up to a higher voltage by a transformer. Then the ac How a is converted back to de by a rectifier, simple SCR trigger after which it is stored in the flash unit's main electrolytic capacitor. provides faster recycling, (Capacitors in modern flash units are capable of storing potentials of about more flashes per charge 350 volts.) The flash capacitor is con­ nected to a gas-filled tube. Xenon is and quick recharge the usual gas used , although some for the latest breed of other types are available. automatic electronic flashers

39 At this stage, everything is set for triggering the flash. What is now needed is a high-voltage pu lse to 100 ionize the gas in the flashtube to make it conductive so that energy can 9-0 ENERGY flow through the tube, where it will be eo SAVED converted to light. Th is high-voltage . pulse is created as the camera's shut­ 70 ter contacts close, causing a small 60 trigger capacitor to release its charge into a spark coil connected to the wall 50 of the flashtube. After the charge on the f lash capac itor has been ex­ 40 hausted, the gas becomes de-ionized 30 and no longer conductive. The re­ charging cycle can then begin. Once 20 the cycle is complete, as indicated by the ready lamp on the flash unit, the 10 flash can again be fi red. ()_ A B c Automatic Flash. Film exposure is based on two factors: time and inten­ sity. Wi th the pre-1965 photoflashers, Energy used by three e~ectrqnic flask units shooting the time factor (flash duration) was tke·.Same sce.ne. At (A), the manual unit:Uses fixed at about 1/1000 of a second for atl the poltage stored in flash capacitor tg most units. Hence, intensity had to be i§lymtnfLW the scene. Proper expQsure is .obtained controlled by changing the camera's '.by~ $e~ting thef---StOp on the camera. In unit (BJ~ lens opening (f-stop). ~ a: <]Jienc:h, tub~ ~ypB., expos'ure w11:t1 controll.ed by-the The Honeywell 660 automatic flash flash unit. pnty 4.5 percl}nt <)[ (.~ e.r.wt'!iY; 'µ)fis u.sed • . to .exp0se thefilm. Flq,_sh_14n£t (QJ use.d tlie same employed the first " quench circuit" ' i:fm~nt of time· and energy .a.it (BJ to illuiinina.f,e the and operated on the variable of time. - ~11,(bj_ect poperly but U)1//18ed eneTfJ'JI re.mq,_ined in the Now, inst ead of just one flash ,dura­ :'fl4'6h c(!,pacitQ"r, resulti'fq} in 'fes'S'ba:@.ry drain tion of perhaps 1/1000 second, the a:a "We}l- a$ a fatfter recy<;'f:ing _t;i'-m;e between 11hots. flash unit would give a burst of light

with a duration of anywhere between 1 40 POPULAR ELECTRONICS TRACES FROM AN ENERGY-SAVING FLASH UNIT 1/1000 and 1/30 ,000 second. The ex­ posure control was taken from the camera, and the photographer put in the flash unit. The photographer had only to set an f-stop on his camera, following the recommendations of the manufacturer based on the light intensity from the flash unit and the ASA of the film. The flash unit would then control the duration of the light. Here's how it works. Light emanat­ ing from the flash tube is reflected from the subject back to the flash unit, where it is detected by a photo­ cell. The photocell is connected to a small timing capacitor whose value has been carefully selected based on known criteria (f-stop to be used with a given ASA of film, lignt intensity, and distance) that add up to an ex­ posure analog. The amount of light falling on the photocell can be biased either by using small apertures or neutral-density filters placed before it. By so doing, the photocell can be fooled into believing that it takes two, three, or four times as long to illumi­ nate the scene. Responding to the amount of light falling on it, the photocell regulates the charging of the timing capacitor. Once the timing capacitor has reached its full charge in a quench-tube circuit, it closes another switch that allows the current flowing from the flash capacitor to be shunted to another tube, with a lower series resistance. Here, the energy is expended in the form of light and heat. This second tube is never seen by the photographer, and its light never plays a part in the photographic pro­ cess. It is just a convenient way of dumping the unneeded energy flow­ ope traces show results ing from the flash capacitor. With this sizing various working approach, flash durations of up to ,ic:;s;o:-11ees by regulating a set of 1/70,000 second have been obtained ~ · front of a Braun 2000 with small electronic flash units, per­ · . then measuring the mitting us to record such things as ash waveform with a bullets piercing wood , balloons ·plier and scope set to breaking, etc. per division. Effective All of this was enough to send most ration varies from photographers into fits of ecstasy, but ,_.c..-.,·-=-.m of 111000 s (equivalent unit on manual or at it still left one problem. Even though ·mllm working distance) to the quench-tube idea brought ,_..._..,... • of 1132,000 s (using unit enormous flexibility to electronic working distance). flash units, they were still energy was­ the waveform on middle ters. There was no feasible way to .:s is from firing of We used a high-speed oscilloscope dam up the energy flowing from the tube. This is a to check flash duration of the flash capacitor to the flash tube. The id'Bl:=neri.stic of some, but not Braun 2000, set to give briefest result was that a photographer could -~ at.est energy-saving flash of 1/32, 000 s. Measurement obtain only a limited number of · s using thyristors. from pulse width at half height. flashes per battery or charge. In the case of the rechargeable nickel­ 41 cadmium battery, this was usually supply the small amount of energy charge. (On manual, these same bat­ about 40 to 60 flashes. necessary to recharge the ca.pacitor. teries would deliver only about 60 Battery power can i::>e conserved flashes per charge. Since no one Enter Thyristor Control. In the fall -meaning more flashes per charge. shoots exclusively at distances of 2.5 of 1972, Braun introduced the first One series-type thyristor flash unit ft (0 .76 m) , the more usual number of series-circuit, thyristor-controlled known to us recycles in about 2.5 flashes per charge is about 100 to flash units. The much-sought-after seconds after illuminating a scene 10 200. breakthrough came in the form of a ft (3.05 m) away. In doing so, it uses Thyristor-controlled electronic small si I icon controlled rectifier only 22 percent of the energy in the flashes are not likely to glut the mar­ (SCR) called a " thyristor." Operating flash capacitor. However, if this same ket in the near future. This type of as an electronic switch , this little unit is fired at a subject 20 ft (6.1 m) flash makes sense only with the more solid-state wonder can handle the away, it will have used up 90 percent high-powered flash units. The low­ load flowing from the flash capacitor of the stored energy and will require 6 powered flash units generally require and stop it at the precise moment that seconds to recharge. At distances of the entire flash charge on the the exposure control circuit says the 2.5 ft (0 .76 m) , the recycling time capacitor to illuminate scenes greater subject has received enough light. In­ would be only about 0.25 to 0.33 sec­ than 10 ft (3 .05 m) away; so, there stead of having a parallel circuit that ond. In the manual mode (with the would be no energy savings by build­ simply reroutes the energy from the photocell covered), or at distances at ing into them a thyristor circuit. Only flash capacitor, we now have a series the very end of the electronic flash 's flash units where a small amount of circuit that allows the leftover energy ability to properly illuminate the energy would be used in a shot would to remain in the flash capacitor. scene, the thyristor does not receive make the thyristor circuit practical The thyristor has many advantages, the reversing pulse from the timing and necessary. among them: It can switch on and circuit. Instead, it opens after the vol­ Another thing barring the universal remain on until the current flowing tage in the flash capacitor has drop­ use of the thyristor in electronic through a de circuit drops to ze ro (or ped to near zero (usually about 1.5 photoflash units is that this type of near zero). It can be made to open if it volts). , SCR is expensive and can be tricky to receives a very brief low-energy pulse Battery conservation goes hand in make. Quality control must be very from the opposite direction. The hand with the storage of energy in the tight, which reduces the number of pulse to shut down, of course, comes flash capacitor. Before the thyristor devices available. This means that from the timing circuit with its small made its appearance in flash units, it thyristor suppliers are having a rough capacitor connected to the photocell. was necessary each time to supply time trying to keep up with the de­ Used in an electronic flash unit, the enough power to bring a fully de­ mand. Manufacturers tell us that they thyristor performs two jobs. First, it pleted capacitor up to full charge. are having troubles trying to get stops the current flowing from the Now, the thyristor has reduced the enough thyristors just to meet the main flash capacitor, thus regulating requirement so that only fractions of demand for flash units now in pro ~ the duration of the flash in the same the earlier power are required to re­ duction. manner the parallel quench circuit charge a partially discharged When you do see a thyristor­ did. And it allows the unused energy capacitor. In some cases, if the flash controlled flash unit, you can bet you to remain in the flash capacitor, unit is used exclusively at the closest will have to pay more for it than you rather than being wasted. This, in working distances ~where the dura­ are accustomed to do for " conven­ turn, provides another advantage. tion of the flash is briefest), it is not tional" flash units. The type of sophis­ Recycling times can be shortened uncommon to obtain 700 to 1000 tication built into these flash units because the battery can very quickly flashes per nickel-cadmium battery does not come cheap. Perhaps when semiconductor manufacturers can crank out this type of SCR the way other manufacturers crank out resis­ tors, a price reduction can be anticipated-but not before then.

Who Makes Them. If you want to look for one of the new thyristor­ controlled flash units, ask for any of the following in your local photo store: Argus Model 1272 or Model 1275; Auto Spiralite Thy 1000; Bell & Howell Model 880; Braun Vario Com­ puter 2000 F022 or F027; Honeywell Auto Strobonar 470; Metz Mecablitz 402 or 217 ; Rollei Model 36 RE or Model 140 RES ; or the Vivtar Auto Thyristor Model 292 or Model 352. Canon, Minolta, and Nikon also mar­ ket this type of electronic photo flash unit outside the U.S. ~ 42 POPULAR ELECTRONICS 4.~~<.

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AN EXPERIMENTAL TV camera LENS moves across the sensor. The number has been developed that is no of elements in an array determines the larger than a pack of cigarettes. ICIII resolution of the picture. The effect of Equipment is being installed at resolution on picture quality is shown supermarket checkout counters that in Fig. 2. Here, the same picture is CRT PISPLAY _ IC IMAGE SENSOR can automatically read price tags. Fig. 1. An image-sensor system. scanned by five different linear arrays. There is even a machine that enables The array with the lowest resolutlon blind people to read ordinary printed A linear array can be used to pro- (32 elements) produced the picture at material. All of these developments duce a two-dimensional picture, but the right, while the picture on the left are made possible by the use of solid- only one line at a time as the image was produced by an array with 512 state image sensors—a special type of integrated circuit. ,a_.;_.'.-_»;w-~»_.-.==-" . ‘I I ...... _.._=_ "~ -in--_ An image sensor can contain hun- =_--='=_-'-‘aw;-;—.-‘r.-__* -l “ dreds, even thousands, of individual ii photosensitive elements on a single chip of silicon. It is normally mounted in a standard IC package that is cov- ered with a transparent top. When a \==..‘§’ scene strikes the image sensor, usu- ally through a lens as shown in Fig. 1, the individual elements of the sensor .__ Q-ra- can be scanned electronically and their outputs displayed.

Area vs. Image Array. The photo- sensitive elements of an image sensor can be in either a linear or an area array. In a linear array the elements are in a single line; in an area array, they Fig. 2. Photos of displays show how resolution affects picture are in a two-dimensional matrix. quality. Number of elements in array increases from right to left. JANUARY 1975 43 e\ements. ihe impro\/ement in quality 2500-element area array is shown in sor. A small camera containing the from right to left is ob\/ious. Fig. 3. "The sensor is e\ectronica\\y image sensor is used to scan a printeo The advantage of an area array over scanned and its video output is dis­ page. The outputs of the sensor con­ a linear array is that the image doesn't played on a CRT. The array used is a trol a 144-element tactile display that a have to be scanned from top to bottom Reticon Model RA50X50 {Fig. 4). blind person can feel by fingertip. This to produce a two-dimensional picture The reading aid shown in Fig . 5 was reading aid, known as the Optacon An example of an imaging system developed at Stanford University and (Optical to Tactile Converter) is being using a lens to image a picture onto a has a 144-element (6 X 24) image sen- produced by Telesensory Systems Inc.

SILICON

(Al (Bl

Fig. 3. Solid-state Fig. 6 With normal light on piece imaging system of silicon (A), resistance is high. using a 50 by 50 More light lowers resistance (B). sensor array. The image can be seen Types of Image Sensors. Inte­ on CRT in front. grated circuit image sensors can be built in a ·number of different ways. The two most common types are the charge-coupled device (CCD) and the MOS scanned photodiode array. Both types make use of the inherent light sensitivity of silicon. The light sensitivity of silicon can be observed by performing the simple experiment shown in Fig. 6. When a strong light is sh ining on the sili­ con device, the resistance of the silicon is seen to decrease. What is being observed is . the process of

i Fig. 4. Close-up photogeneration. When light interacts of the Reticon with silicon, current carriers (both RA 50 x50 sensor. holes and electrons) are generated, The background is reducing the resistance. In fact, each photo of the array photon that interacts produces one magnified many times. hole and one electron (sometimes called a hole-electron pair). Silicon is not uniformly sensitive to an wavelengths of light. In fact, silicon image sensors are generally much more sensitive to red light and the

...... J "'0 Q ;; z "' " ::i"' ... Q ".... ~"' ..J "' ... "' ...,,, ::i m :!': z "' "' 0 "' ,,,0.. "'

0.2"00 o.4oo o.soo o.aoo 1.000 1.200 WAVELENG "J; H (MICRONS) Fig. 5. Reading aid for blind is used by scanning letters with sensor Fig. 7 Spectral response of in right hand andfeeling them with left hand on tactile display. silicon to various colors of light. 44 POPULAR ELECTRONICS

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75 CONSTRUCTION AN· IGNITION Tiit/i/NG LIGHT FOR INIPROVING GAS ECONONIY

BY ANTHONY CARISTI

OWADAYS, everyone knows how under conditions of bright daylight, The stepped-up voltage from the N important it is to get the best gas and it is battery-powered (from the secondary ofT1 is again stepped up by economy possible from an au­ car's battery)to make it independent the voltage-doubler circuit consisting tomobile. One of the more important of the ac line. of 01 and 02. It is then passed into factors that affect economy is engine flashtube FT1. · timing. In addition, proper timing is About the Circuit. The heart of the required on all automobile engines so timing light's circuit (Fig. 1) is de-to-de Construction. Perhaps the most that exhaust emissions do not exceed converter transformer Tl. It alternately demanding part of the construction allowable limits. switches current between transistors process is the winding.of T1 . Even so , Timing changes for a variety of 01 and 02, while stepping up the bat­ the job is not difficult, only time­ reasons. As the parts of an engine tery potential to about 125 volts. A fer­ consuming. The transformer should wear, the timing tends to become re­ rite pot core was chosen for this cir­ be wound in the following manner: tarded. If ignition points are replaced , cuit to keep down project size and Start by winding the feedback loop timing is also .disturbed. Furthermore, cost. (its leads are labelled 1 through 3 in it is virtually impossible to set the point The primary winding of T1 (wound Fig. 1) on the bobbin supplied with the gap exactly the same as it was when around the pot core) is done by the ferrite core. Use No. 30 enameled wire. the timing was la~t set. " bifilar" method that gives tight cou­ This winding coneists of 10 turns of Using a dwell meter is a far more pling and accurately locates the wire, interrupted at the 5th turn for a accurate method of setting point gap center tap . The tight coupling is es­ center-tap connection. Connect and than using a feeler gauge, but even sential to keeping the voltage spikes solder 5-in. (12.7-cm) lengths of this will not guarantee proper ignition across the transistors to an absolute stranded hookup wire to the ends an d timing. The fact is, the best way to minimum. (In this type of circuit, the center-tap of the winding. Label the check ignition timing is with a timing spikes can easily exceed ten times the leads 1 at the first turn, 2 at the center­ light. supply voltage if a poorly designed tap, and 3 at the final turn. Then wrap The timing light described here can transformer is used causing transistor the winding with a layer of thin Mylar be built for only a few dollars. Yet, it is failure.) By using a bifilar winding for or plastic tape. designed to perform as well as a the primary, the voltage spikes across Next comes the bifilar-wound pri· commercial unit costing $25 or more. 01 and 02 are well below the 60-volt mary winding . This consists of 27 Its light output is bright enough to use rating of the transistors. double turns of No. 30 enameled wire 50 POPULAR ELECTRONICS sembly_ Be sure to accurately count the number of turns as you go. How many turns you wind will determine the de potential applied to the flash­ tube. When you are finished winding, attach 5-in . lengths of stranded hookup wire to the winding ends and label them 7 and 8. Then wrap the turns with tape. Now you can begin assembling the circuit proper. A printed circuit board is recommended for component mounting (see Fig _ 2 for actual-size etching and drilling guide and com­ ponents placement diagram). Transformer T1 is mounted on the board with the aid of a 6-32 x 1-in . machine screw, fiber washer, (at the top of the transformer), and a 6-32 nut. Do not overtighten the hardware

~:f. - "( ' or you will crack the core, render­ r3z.52H fertite -core anamk . ing it useless. (Note : Capacitor C4 RE '22J3'-.6:12hoQbfµ '(See_'ex-tf ~: mounts on the board atop C3 as shown 7F1asnligbJboay (s~ , text); 'colo(7;. '\ \:l;ed 'test'-leaskcables; ·a1ilgator ­or,':· in Fig . 3) e:k&lil'~clips 'Witll:irts.U!attcf6oois:( 2) ; .:·-~-­ When the circuit board assembly is i>~i- grottim:er;;printetl cii~uit board;.>! completely w ired , temporarily con­ w-, .Corritnk ' Sifas'tic® - cement;' .i nect to the appropriate points on it red rn:~ llard_ware; -stranded"hooktip < and black hookup wires for the posi­ ~ -Nb.:.10!ano No. 36-enaiilele'd Wire;·: ; · -•iYAA:.SiiiY:I< p1Jig ~tiie c"ortnect

HE inexpensive four-func­ Scientific calculators may be capa­ 200-decade scientific calculator costs T tion calculator is an emi­ ble of obtaining nth roots and nth only $89.95 in kit form. It is 33/s'' wide, 611 nently practical tool for everyday powers; trigonometric functions long, and 1112'' thick. home and primary-school use; how­ (sine, cosine, tangent, etc.); natural ever, high-school students, engineer­ and common logarithms; degrees-to­ What It Does. What can you, as an ing and science majors in college, and radians conversions; and many other electronics experimenter, do with practicing engineers and scientists functions. As a general rule, these cal­ such a calculator? The answer is, just require more sophisticated equip­ culators also feature at least one level about anything you want to do in prob­ 'Tlent. Fortunately, there is a new of store/retrieve memory, a 10-digit lem solving. For example, suppose ::>reed of calculators that is rapidly mantissa with two-digit exponent, and you wanted to know the equivalent re­ ;Jaining popularity in professional and separate displays to indicate negative sistance of a network of three resistors advanced-student circles. Going by quantities (in both mantissa and ex­ (560 ohms, 390 ohms, and 670 ohms) such names as " scientific" and ponent) and overflow and disallowed in parallel. By hand, this problem ·· slide-rule" calculators, they expand functions. might take you 10 minutes or more. :Jy several magnitudes the number of Most scientific calculators with the With the calculator, less than 30 sec­ 'Jnctions and the information­ capabilities described above sell for onds is needed to get the answer "'andling capacities of "ordinary" cal­ $150 or more at this writing. But the (171.1638788.) . :Jlators for limited uses. POPULAR ELECTRONICS full-function, Approaching a more difficult prob- JANUARY 1975 53 ·"" ..., ~a .!.N > -N ... 0:: . [fil - + .. ~ 110, - I ~ -~ ~ E1 _,_ ~,. > = o · ... .. co O> (,) .., .a; ... H ..;;;: ""' ...... -~i ~"' 'i ff! ...~· :..Gi11 0 I ~ ~ ~"' CD 0 0:: c - -"' ...... > (!; + .... CJl ~ N ·I'-: co ~~ : 0 -=I ...> ,.!."'

"'(,) . - "' !2 "' ... H "' .,. ,, = ' ·' ~ ~· ·~ ~ Q ...> ! "'~ "'

!! !!? ~ ~ ! ~ =~ O> ID co "' ... 0::1 otDrt'>"l;f"IOI'-- o_ "' O> "'.,. "' 0 0 0 0 0 0 0 0 0 0 0 "'(,) c 0 "'"' H "' 11 ,.,:. "' - 0 ... co 0~,.4 ~ .,. N > "' N "' N "' "' ~1 '*'I - ... "' "' "'"' "' (,) j :z ~@

(,) z ... ::E H...... ~-5 > ~ :E .,. "' Cl) 21 "' "'~ N °'! ... I~~,,. II• "' - "' "' ... +-(,)"' O::N I "'0:: "'..: ;:; ~ H "' I• !::: ~ "' o~ 11 o- 21 ~ ~ !: ~ !2 .,. "' "' "' - "'"' "' - ~~{ 000000 iOOOOOO1 T"':- ; ... Q\ ..1 00 0000 ~OOO' rO'> - --1· rll• coC: - N IO ~ >- >- >- >- Ir~ ~ 00:: oo H "'D >- -~~ + N,.._IL. "' --u ..;.::1. Fig. 1. IC1 and IC2 are special MOS O> ! C's that accept the keyboard commands, "'... ·~"',.; · "'~ perform the required operations , ,0-.... and deliver a signal for the 14-digit I 11 ~ I l'lllll I LED display. The other ! C's form rt) :.:-J-, i:t::NJ-O > the interface between the MOS and LE D's . "'...... ,.,...:~ ID + The two-way transistor power supply generates "' I the negative voltage needed by I C1 and IC2. 11• +:11.- ~~~~- ~ ;;!; - -- ~tfi=_..,.,x ... tt :;­ 54 POPULAR ELECTRONICS The POPULAR ELECTRONICS cal­ only a 7-volt battery is used in the cal­ culator has built ihto it two levels of culator, a two-transistor (01 /02) dc­ nested parentheses, each of which de­ to-dc voltage converter is requ ired . In fines a variable before executing a conjunction with T1, R4, and C2 , the function command. This permits the 01 /02 circuit forms a push-pull power problem to be " written " into the cal­ oscillator. The output of T1 is rectified culator exactly as it is written down on by 01and02. It is then filtered byC3 to paper. When a new parenthetical deliver the -7 volts required. Transis­ statement is opened, the previous re­ tor 03 is the power-saver switching sults and functions are stored in the regulator, while potentiometer R3 calculator until that level of paren­ permits adjustment of the battery's theses is closed later in the problem. low-voltage cutoff point. So, a complex problem like Rectifier diode 04 converts the ac from the plug-in charger to pulsating de for charging the two batteries. x =sin 1 ~3 Zener diode 05 keeps the voltage from + v' (a + b) 2 - (c + d)2 exceeding the approximately 8 volts ~ required for recharging. An optional where a= 4, b = 5, c = 2, and d = 3 can resistor (R1) is used to limit the charg­ be solved quickly with the aid of the ing current to a safe level. parentheses. The keystroke sequence would be: 1, +, (, (, 4, +, 5, ), x2 , -, (, 2, Construction. There is no practical +, 3, ), x2 , ) , Vx, = , 1/x, sin, xY, 3, =. way of assembling the calculator When the last keystroke is executed, without the aid of a printed circuit the display will read the answer, board. Unfortunately, since the board 8.70831579 -09, which means that the must have conductors on both sides mantissa is the number shown raised to the negative ninth power of 10 (10-9) , which means further that the calculator employed another bu ilt-in feature-automatic scientific nota­ tion. (The calculator goes automati­ cally to scientific notation whenever the solution is an excessively large or an excessively small number.) Note that in the above sample prob­ lem no memory or external scratch­ pad was required to find the solution.

About the Circuit. The schematic diagram of the complete scientific calculator is shown in Fig . 1. Special MOS integrated circuits IC1 and /C2 are the heart of the circuit. They ac­ cept keyboard entries, perform all mathematical operations demanded, and deliver a multiplexed output to the Jem, suppose you wanted to know the driver circuitry for the 14-digit LED equivalent impedance of a 560-ohm display. (The display consists of 10 resistor and a 25 .5-mH choke at 2500 mantissa digits, two exponent digits, Hz. The solution, 687.5569736, takes one negative-sign digit for the expo­ about a minute with the calculator, nent, and a final digit that combines considerably more time with paper the disallowed-function, minus-sign, and pencil. and radian-function notation to the To" give you a better idea of how left of the mantissa.) practical the calculator is, you can Buffers /C3 through /C5 drive the 14 throw away your logarithm and trig­ digit-enable lines, while /C6 and /Cl onometrytables. You won 't need them are the segment drivers for the dis­ again because they are only a few play. Note that all similar segments are keystrokes away in your calculator driven simultaneously, with the digit -all figured out to an accuracy of nine selector choosing the correct digit of decimal places. And that goes for n as the moment. well. (A more detailed list of the Because the MOS chips require capabilities of this calculator is given both positive and negative 7 volts de in the box.) referenced to common to operate and JANUARY 1975 and the components must be mounted as close to the board 's sur­ face as possible, there is no practical way of making this board at home. While you might be able to make the required double-sided board at home with all points properly registered, there is no known method that can be used at home to plate-through the holes. Hence, you will have to pur­ chase the pc board from the supplier listed in the Parts List. Shown in Fig. 2 is the component­ placement guide for the main board assembly. The view is from the com­ ponent side of the board . (The two sides of the board are readily identifi­ able because the bottom side on which no components are mounted bears the legend BOTTOM.) Fig. 2. Component Start assembly by installing and placement on the soldering into place the fixed resis­ component side tors. Then proceed to installing the of the pc board. three electrolytic capacitors, the diodes, and the transistors, taking care to observe proper polarity and basing. Mount the transistors close to the board's surface. Use a fine­ pointed soldering tip, thin-strand sol­ der, and a minimum of heat. Fre­ quently clean the soldering tip with a damp rag to remove excessive buildup of solder. This will minimize the possi­ bility of solder bridges between the closely spaced foi I conductors. Do not touch or remove the MOS /C's (IC1 and /C2) from their carriers until in­ structed to do so. If you inspect T1 , you will note that there are three pins in one of its cor­ ners. These pins serve as the i nstalla­ ti on " key." Install and solder into place the transformer. Potentiometer R3 mounts in the upper-right corner of the board. Then install IC3 through Straighten a strip of 24 Molex the board . This time, use a 2-in. IC7 in their respective locations, care­ Soldercon ·~ connectors but do not (51-mm) length of masking tape. (The fully observing the notch code. As you remove the connector strip. Force the upper strip of connectors is for the proceed, carefully inspect the board end pins of the strip through a 2Y2-in . display interconnect, while the lower for the presence of solder bridges. If by Ve-in . (16- x 3.2-mm) piece of mask­ is for the keyboard interconnect.) you locate a solder bridge, reflow the ing tape from the non-adhesive side. Straighten four Soldercori strips, solder and remove the excess. Mount the connector strip in the holes each consisting of 14 connectors. In­ Install the two flat (negative) battery just below the five IC's at the top of the stall these in the holes for IC1 and IC2 . contacts as shown. Solder them at board, pressing down to seat the tape Then, before breaking away the con­ both ends and on both sides to the firmly against the board 's surface. Flip nector strips, make sure the connec­ copper conductors. (Note: There are over the board and solder the protrud­ tors are straight and that the IC pairs small holes in the board and the bat­ ing pins to the copper foil. Be very are parallel to each other. Now, before tery contacts are dimpled. When careful to avoid solder bridges. Flip you even consider opening the carrier properly installed, the contacts are over the board again and, using long­ in which IC1 and IC2 are packed, care­ positioned with their dimples engag­ nose pliers •.bend the connector strip fully read and become familiar with ing the holes.) Install and solder into back and forth until it parts from the the procedures for handling MOS de­ place the spring-type battery contacts, connectors. Be careful to align the vices by reading the instructions given making sure that the pin-connector connectors properly. in the box on page 57. side is vertical to the plane of the In the same fashion as described With yourself properly grounded board. Mount and solder into place above, mount a strip of 20 Soldercon and all conditions for good MOS· jack J1. connectors along the lower ed~e of device handling met, open the carrier 56 POPULAR ELECTRONICS With the IC's still in the carrier, deter­ in the case, secure the two together Checkout and Adiustment. Plug mine which is which and the locations with small nuts over the threaded the recharger into J1 and let the bat­ of pins 1. Pin 1 is near the small bump posts. (Note: Because of possible in­ teries charge for a few hours. Then on each IC. To be absolutely certain of terference between nut and close-by disconnect the charger. Remove the pin 1 on each IC you can use a small foil conductor near the left post, pre­ tape from the power switch and set it magnifying glass to check the IC leads cede the nut here with a thin insulating to ON . The right-hand mantissa digit near where they enter the packages. washer.) and its decimal point should come on, Only pin 1 in each case has a tiny hole Place the power switch in the OFF displaying 0. Leave the power applied drilled through it. position, and tape it in place until the and, after about a 30-second delay, the With the forefinger of the hand you .batteries have been installed. The bat­ 0 and decimal point will blank out, have grounded pressed against the teries are marked with +and - signs. being replaced by a minus sign in the metal plate on top of IC1 remove the IC The + sides are protected by sleevings exponent display. This indicates that from its carrier. Check to make sure its that extend beyond the bodies of the the battery-saver feature is working. leads are in straight lines. Then care­ batteries. The sleevings are notched in Press the clear (C) key to restore 0. fully install the IC in its appropriate such a manner that the batteries will fit to the display. Feed in the numbers 1 connectors on the board. First engage into their respective locations in only through O; operate the + / - and EE the pins along one side of the IC in the one way. Slip the batteries into place. (enter exponent) keys; feed in 88 ; and connectors. Once this is accom­ This completes construction. press the+/- key. The display should plished, work the leads along the now read -1234567890-88. Press the other side into their connectors. Apply degrees-to-radians key; a small fi rm , even pressure to the IC to seat it diagonal bar segment should come on in its connectors. Do not force the IC to the extreme left of the display. Op­ into the connectors or subject it to tor­ erate this ·key again , and the bar sional forces or you might misalign or should extinguish. Press the C key. even break off pins. If insertion is dif­ Press then key. The display should ficult, replace the IC in its carrier. now read 3.141592654. Depress C. Then, insert and remove an old IC in Now, with 0. displayed in each case , the connectors several times to press log (common logarithm), ·1 n " form " them. Any DIP IC wiil do; just (natural logarithm), and 1/x (recip­ make sure to cover all connectors. rocal). In each case, before depres­ Now, install the IC from the carrier. sing C, the disallowed function indi­ Repeat the above procedu re for IC2. cator, an inverted L, should show at The display comes as a completely the far left of the display. wired assembly, with its 24 connector To adjust battery-low indicator pins already mounted in place. Just potentiometer R3 , it is necessary to make sure that the pins are in a first fully charge the batteries. Plug the straight line. Carefully fit the display­ battery charger into J1 and the ac out­ board pins into their respective con­ let. With the power switch set to OFF, nectors on the main board. Press the charge the batteries for about 8 hours. display board into place so that it rests Then use the calculator for about 4 on the five upper IC's with a sl ight tilt. hours. Then, with the power ON, adjust The keyboard also comes as a com­ R3 with a thin-bladed screwdriver plete asserribly, including connector through the hole in the bottom of the pins. Straighten any out-of-line pins main board, until the battery-low indi­ and engage them in the connectors cator (an L at the left of the display) along the lower edge of the main comes on. board. Gently seat the keyboard as­ Install the back of the calculator sembly in place until the narrower por­ case by inserting the two bottom tions of the upper two plastic posts on " hooks" into their respective slots at the keyboard assembly engage the the bottom end of the calculator. The smaller of the holes above the top end simply snaps into place. A nar­ negative-terminal battery contacts on row slot at the top of the case is pro­ the main board. vided to permit the case to be Slide the entire assembly into the reopened as desired with a coin or top half of the calculator case until the screwdriver blade. Simply twist. two small plastic tabs on the bottom The calculator can be operated from end of the keyboard engage the fully charged batteries for about 4 to 5 molded slots in the case top. At this hours. When the charge runs down, t ime , two threaded plastic posts simply plug in the recharger. Recharg­ should appear through the holes im­ ing takes 8 to 10 hours. The battery mediately above the negative battery charger can also be used as a conve­ contacts on the main board, and J1 nient battery eliminator. However, should slightly protrude through its under no circumstances should the slot in the case. recharger be used if there are no bat­ Holding the board assembly in place teries in the calculator. ~ JANUARY 1975 57 CONSTRUCTION

IC Speed Controller for HO Model Railroads Precision low-cost device provides full control flexibility and simple speed indication option

BY ROBERT D. PA SCOE

ITH A PAIR of integrated­ ual indication of how fast the train is wiper at potentiometer R2 and the de W circuit operational amplifiers moving on its tracks. The faster the voltage across capacitor C3 . Op amp and a handful of parts, you can build a train moves, the brighterthe light from IC2 is connected in a voltage-follower precision speed controller for HO­ the lamps. configuration. The de voltage across gauge model railroads at minimal C3 , the reference for the regulator, is a cost. The solid-state controller tea­ About the Circuit. Operational am­ product of the time a constant current . tures forward/ reverse, stop, in­ plifier IC1 , in conjunction with transis­ is " pumped" into the capacitor. The crease-speed, and decrease-speed tors 01 and 02 (see schematic dia­ two current " pumps" in this system switches for full control flexibility. In gram), forms a voltage regulator cir­ are made up of the 03 and 04 circuits, addition, optional lighted pushbutton cuit. The output voitage from this cir­ with 03 the negative and 04 the posi­ switches can be used to provide a vis­ cuit is determined by the voltage at the tive pump. 58 POPULAR ELECTRONICS TO OP AMPS +v QI RI HEP703 .7IL

Cl +

1000 pF

C2 Q3 R3 Q4 HEP801 4.7K HEP801 C3

+ IOOpF

R4 4,TK

s3 L s2 I SJ I STOP r DEC. r INC . r Controller circuit is variation of a power supply regulator. Potential on C3 determines track voltage level.

PARTS LIST

Cl-1000-µF, 50-volt electrolytic capacitor Q2-2N4400 transistor (or use Motorola S4-Spst slide or toggle switch Ci, CJ..:--100-µF, 50-volt electrolytic capac­ HEP-736) S5-Dpdt, center-off switch itor Q3 , Q4-HEP-801 FET (Motorola) Tl-26.8-volt, I-ampere transformer Dl-D8-1N4003 (or similar) silicon diode Rl-0.7-ohm resistor (four 3.3-ohm, Y2-watt Misc.-Heat sink for QI; suitable enclosure; Fl-0.5-ampere fu se resistors in parallel) fuse holder; socket(s) for IC I and IC2 ; 11-13-6-volt pilot lamp (optionally in Sl-S3) R2-I0,000-ohm potentiometer pe1forated board and solder clips; line IC 1, IC2-74I operational-amplifier inte­ R3 , R4-4700-ohm, Yi-watt resistor cord; strain relief or rubber grommet (for grated circuit (or use dual version) Sl-S3-Normally-open pushbutton switch line cord exit hole) ; dry-transfer lettering JI, J2-Banana jack (one black, one red) (Use SwitchcraftNo. LUS-05-01 if built-in kit; machine hardware ; hookup wi re; sol­ Ql-HEP-703 power transistor (Motorola) 6-volt lamp is desired) der; etc.

Depressing increase speed switch terminals and sockets for IC1 and IC2. specified in the Parts List, the voltage S1 causes the output voltage at the Series-pass transistor 01 must be change rate is about 2 volts/second. tracks to increase. Conversely, de­ mounted in an aluminum heat sink Increasing the values of R3 and R4 pressing S2 causes the output voltage with about 9 sq in. (58 sq cm) of rad iat­ decreases the rate of change, and to decrease. And pressing stop switch ing area. vice-versa. ~ S3 causes the output voltage to im­ You can mount the circuit board as­ mediately drop to zero. sembly and transformer in any suita­ A visual indication of the speed at ble enclosure. The control switches which the train is moving is obtained and potentiometer are best mounted by observing l:low bright the light is on the top of the enclosure, wh.ile out­ from lamps/1-/3. One of these lamps is put jacks J1 and J2 are more conve­ (optionally) inside each pushbutton niently located on the rear of the en­ switch. The greater the track voltage, closure, as is the exit hole (strain re­ the faster the train is moving on the lieved or rubber-grommet-lined) for tracks, and the brighter the lamps. the line cord. The three-diode current limiter composed of 05-07 holds the current In Use. The upper voltage limit to the being fed to the tracks to approxi­ tracks is determined by the setting of mately 1 ampere. Hence, the circuit is potentiometer R2. To adjust R2 , de­ protected in the event the train tracks press increase-speed switch S1 for 10 should accidentally be shorted to seconds. The glow of the three lamps each other. will increase in brilliance during this interval. Set R2 for the desired upper­ Construction. Owing to the simplic­ limit track voltage. ity of the circuit, the entire controller, The speed at which the track voltage except for T1 and the switches, can be increases and decreases is deter­ So why should the experimenter have mounted on a piece of perforated mined by the two current pumps (03 to start from scratch when we can board with the aid of push-in solder and 04) . With the components give it to them in kit form! :JANUARY 1975 59 BY DON LANCASTEFI

PART t

The keyer

combines pitch

and envelope iaformati.on in

an amplifier to shape a realistic mode.

PQEYING circuits go by many A very few older orga111.s did netem­ one Individual keyer can be lWPPlied LfU narnes. In organs, they are called ploy keyers. They slmp.ly ¥>Plied and with eac;h note in a polyphoniclWSfem. simply keyers: in traditional electronic removed the supply voltage to ~nd We can use much more sophisticated synthesizers, they are often called from oscillators or .u.sel the keys keying circuitry if we need only a.f.ew , voltage-controlled amplifiers (vca's), themselves al!! off/on note controllers. rather than on.e for each note. Keying envelope shapers, or modulators. Enveiope shaping ability is very lim­ or envelope shaping can take place Functionally, they are electronic m1..n­ ited by this means. At the other ex­ either before or after the tinbre or tipliers. All of them do the same job­ treme, some true computer compos­ tone-quality circuitry, working either -they combine pitch information with ing circuits and programs completely with the raw frequencies as gener­ the envelope information to produce a specify the amplitude and frequency ated or the final highly structured har­ realistic note or note sequence. instantaneously. With these excep­ monic tone. Organs usually employ Done properly, this sets the attack, tions, virtually every other electronic fixed formant filters; and a polyphon­ sustain, tailback, decay, and snubbing music system generstes tones and en­ ic instrument is usually keyed first of any note on an individual basis. En­ velope information separately. These and vol.ced later. In synthesizers, the velope control can also introduce two signals are then routed into a cir­ note will more often be colored by a such special effects~ percussion, the cuit that provides a combtnation of the patchwork of voltage-controlled "bite" on the leading edge of a horn desired loudness and frequency. oscillators (vco "s) and filters (vcf's), sound, echos. tremelo, and noise The keyer or vca might work on any and then envelope shaping takes modulation. note in a monophonic instrument, or place. 60 PflPlllAR ELECTRON!' of the tone or waveshape without be­ the direct current through the diode. If having like a low-pass filter. there is no current, the diode is an To be useful in a circuit, the keyer open circuit. For small direct currents, should ha\/e a medium-to-high tone the impedance presented to ac signals input impedance and a low output im­ is given by the ratio 26/1, where I is the pedance so that it can drive output current in milliamperes. So, a diode and timbre circuitry without difficulty carrying a 0.5-mA current "looks" like and does not load down the tone 52 ohms to a low-level ac signal routed source too heavily. The impedance at through it. the envelope input would ideally be In Fig. 2A, one capacitor is used to infinite so that large-value resistors couple a tone into the diode and use and economical small capacitors the envelope information to set the di­ could be used for attack-sustain-de­ rect current through the diode. The cay shaping. This is particularly im­ disadvantage of this circuit is that it portant on polyphonic instruments will thump as the envelope appears in where a hundred or more keyer cir­ the output. A second diode and equal cuits might be needed. positive and negative signal swings Keyer design is no simple task, since (Fig. 28) from the envelope circuitry it shares all the woes of any faithful overcome this disadvantage. The two electronic analog or digital multiplica­ diodes are in series across the en­ tion problem. Let us look at some velope circuit but in parallel with the popular approaches to keyer design. tone input. Two more diodes (Fig. In this first part of our two-part article 2C) eliminate the extra coupling on keyers, we will discuss diode, capacitor. differential-amplifier, four-quad rant Input impedance is low, output im­ multiplier, and gain block keyers. Next pedance is high, and a wide voltage month, JFET, MOSFET, Transcon­ swing into a medium resistive load is ductance-amplifier and CMOS keyers. needed for the envelope input. But if the diodes are identical and if the con­ Diode Keyer. The diode keyer is trol voltages are also identical, and if by now, fairly obsolete. An ordi­ the ac signal level is low enough, the nary silicon diode has its small-signal diode keyer can operate without in­ (50 mV or less) ac impedance set by troducing intolerable distortion, and it

What a Keyer Does. Any keying cir­ 1cuit must simply control the gain of 1the tones fed through it. In Fig. 1 are 1 shown some good and some bad things keyers do. The keyer must be­ •: have as a linear, electrically bilateral 1'variable resistor. Ideally, it must intro­ 1 duce no coloration or significant dis­ tortion of its own (Fig . 1A). A keyer must be transient-free. This means that no ringing or overshoot can be permitted as in Fig. 1B. It also means that no feedthrough of the en­ velope information to the output can be permitted (Fig. 1C). The result of feedthrough is a loud thump and other response-recovery problems later on in the circuit. Any keyer circuit in which the de output level changes as a ~ unction of the envelope command is ,bound to be a bad design and will hump badly. A keyer must treat positive and _, egative signal swings equally, am­ ~ l ifyi ng or attenuating them with equal gain (Fig. 1D). And the keyersys­ em must have a wide enough fre­ ~uency respqnse to follow faithfully the envelope and pass all frequencies JANUARY 1975 61 ' will not cost much to make. (A diode available current and because 01 's similar devices exist, the RCA CA3000 keyer will always add some distortion.) output impedance is equal to the input series linear IC 's offer many differen­ Various transistor schemes have impedance of 03, which yields a sec-· tial-amplifier possibilities. An ordi­ been used in keying setups. They are ond 2:1 attenuation. nary 741 or 5558 operational am­ basically diode keyers that use the It is important to note that the gain is plifier can be used to eliminate the base-emitter junction$ of transistors directly proportional to the emitter common-mode thumping on the last as the multiplier elements. They ease current. Change the voltage on input stage. The differential-amplifier vca the loading and impedance problems, Y, and the gain changes, and the offers good input and output imped­ but they can introd.uce thumping if product of the envelope and tone ances, controllable gain, and large they are not properly designed. Today, input signals is obtained. This type of signal swing. The envelope signal we have much better methods. circuit is called a vca. It bilaterally and must be referenced to a negative sup­ at high speed gives the product of the ply, and the input impedance might Differential Amplifier. In Fig . 3A is two input sig·nals. be a bit lower than we would like it to shown a differential amplifier. It is the One obvious problem with this cir­ be . Dynamic range is good and distor­ most commonly used amplifying cir" cuit is that the de drop across 03's tion is low, but the system becomes cu it at this time and is found in almost collector load res istor follows the en­ a bit complex if a separate circuit all linear integrated circuits. A differ­ velope, resulting in two output is used for each polyphonic note. The ential amplifier normally amplifies the term$-the desired shaped tone and differential-amplifier vca is a very difference between two input signals. an undesirable thumping from en­ good choice for monophonic synthe­ In Fig . 3A, one input is tied tq ground velope feedthrough. In Fig. 38, a sec­ sizer circuits. to provide single-ended-input opera­ ond load resistor, in the collector cir­ tion. This circuit can be used as a cuit of 01, has been added. This cir­ Four-Quadrant Multiplier. A four­ keyer by routing the tone signal into cuit has two outputs, one of which is quadrant multiplier is a true electronic input X and the envelope into input Y. in-phase and the other out-of-phase multiplier that provides the product of If a fixed voltage is applied to input with the input. Both outputs bounce the envelope and pitch inputs directly. Y, some emitter current will appear in up and down together. No offsets are needed on the envelope 01 and 03. Input A goes to 01 and A good differential amplifier ignores input, and the output is normally ref­ comes out of the transistor's emitter. the common-mode up-and-down erenced to ground. The emitter signal drives 03, which is bouncing of the input signals. It is only A typical four-quadrant multiplier operated as a grounded-base stage, the difference between the two signals circuit is shown schematically in Fig. and an amplified version of the input that matters. So, by simply adding still 4. The multiple paths through all the signal appears at 03's collector. another differential amplifier stage to differentially-arranged transistors The gain of the circuit in Fig. 3A is the one shown in Fig. 38, the output provide for automatic cancelling of obtained from the formula IR/104 stays ·at a fixed de level regardless of common-mode feedthrough and where R is the 03 collector load resis­ the envelope and is a thump-free rep­ thumping . As a someti mes handy tance in kilohms and I is the emitter lica of the desired signal. gimmick in some advanced synthesiz­ current in 03, the 104 comes about Differential amplifiers are widely ers the phase of the tone signal is re­ because 03 receives only half the used in synthe$izer vca's. While many versed by inverting the envelope. are too costly if you are considering using one for each note in a poly­ phonic system. Aside from this, ttre four-quadrant multiplier is just about the best you could hope for.

Gain Block. Several linear IC's offer remote-controlled gain capability that can be used as a keyer circuit. Motorola's MFC6040 is a typical ex­ ample of such a circuit (Fig. 5). It costs about $1 . Its circuit is one more variant on the differential-amplifier theme +16V

\Mil 1.0,uf 5 To~ 1NPur /Ootn V

fff;];,Efo.DPE\,.J f-3.5 //OJ..TS= 01>/ r5.S'V

with common-mode bucking. Typical voltage gain, wide open, is 3:1 or 10 dB; attenuation can go as low as 70 dB below full output. Typical four-quadrant multiplier in a multiplier of your own design. The output swing of the MFC6040 IC's include Motorola's MC1595 and The only real disadvantage with the can be up to 6 volts peak-to-peak. One Analog Devices' AD532. Alternatively, four-quadrant multiplier is its cost. potential disadvantage of the circuit you can use the much lower priced None of these IC's is inexpensive. is that the attenuation is somewhat Signetics 5596 as the key component Some exceed $20 each and obviously nonlinear. ~

SCANNING MONITOR RECEIVERS HF/FM •VHF/FM • UHF/FM

Now-the "Sentinels", a stJries of fine monitor receivers joins the big, world­ wide-accepted line of SBE communica­ tions equipment. Single or dual band models of these versatile, applicatlon­ oriented SBE scanners provide coverage of the most widely used VHF/UHF bands. For example, the six different receivers available give FM reception and positive scanning operation for business, indus­ 8 channels-continuous "scanning''. trial (including RCC and other mobile tel­ Receiver locks on first ch;rnnel Big audio volume-3 to 4 watts. ephone), law enforcement, fire, highway on which signal appears. • Fractional microvolt sensitivity • Squelch • Built-In speaker • Jack emergency, traffic advisory, marine-in­ Priority channel feature: Receiver for external speaker • Crystals used shifts instantly to designated chan­ cluding intership I Ship-to-shore I Coast are readily available types not included). nel whenever carrier appears on it Guard/Weather - many other services. Complete w/ plug-in telescoping anten­ regardless of existing channel status. SIX MODELS: na, mobile mounting bracket and cord, Channel lock-out buttons: Unwanted plug sets for 12VAC and 115VAC. Sentinel I: Hi-144-171 MHz, Lo, 30-51 MHz. channels can be locked out. Sentinel II: 144-171 MHz. Write for Brochure Manual advance button allows chan­ Sentinel Ill: 30-51 MHz. nels to ba scanned manually. Sentinel V: 450-470MHz. Base or mobile (AC or DC). Use in Sentinel VI: Hi-450-470MHz, car or home/ office. Operates both [Seel LINEAR SYSTEMS, INC. Lo-144-171 MHz. on 12VDC for mobile and llSVAC for 4l> Sentinel VII: Marine, 156-164MHz. home station. 220 Airport Blvd., Watsonville, CA 95076.

CIRCLE NO. 32 ON READER SEP.VICE CARD JANUARY 1975 63 TUBE & TRANSISTOR TESTER

NTS DIGIT L GR-20110 SOLID STATE COLOR TV WITH 315 SQ. IN. PICTURE AND VARACTOR DIGITAL TUNING As ah NTS sttJ.aent you'll acquire the know-how that better equipment that gets you better equipped for comes with first-hand training on NTS professional the electronics industry. eqL,lipment. Equipment you'll build and keep. Our' This electronic gear is not only designed fQr train­ eourses includ.e equipment like the 5" solid-state ing; it's field typ~ - like you'll meet on the ic:>b, er osoillos.00p&, tran~istor ana tut>e--testef, vec:;t<:>r moni­ when you're making ~ervice calls. And wltb. NTS tor sc:;ope. 74 sq. in. B&W nl, and solid state stereo easy-t0-read, profusely illustrated lessc:>ns y0u learn AM-FM receiver. The unrE:fue NTS Digital GR-2000 the theory behind these teols of the trade. color TII with first ever featui:;,es like silent varactor ChQose from 12 NTS courses c:ov.ering a wide range ciio'de ti.Jning; digit~'! channel selection, (With Op­ of fields in electronics1 each complete with _equip­ tional digitar c:;Lock,~ ar.id big 315,sq. in. ultra r.ec;;tan­ ment, lessons, and manuals to make your training g,IJl~r s~reen 1 This is Just a s~mpliA. 9 ·ot the kind ef m0re 1pr-actlc:al and lntere_stin-g. -lmulatedDt eceotloni------~--~---- 0 COLOR TV SERVICING 0 B&W TV AND RADIO SERVICING The better 0 ELECTRONIC COMMUNICATIONS 0 FCC LICENSE COURSE etter 0 ELECTRONICS TECHNOLOGY NTS TRAINING EQUIPMENT FEA~ 0 COMPUTER ELECTRONICS 0 BASIC ELECmONICS TURES SOLID•STATE COMPONENTS. 0 AUDIO ELECTRONICS SERVICING PROJECT METHOD COURSES DOpt . 205-025 MAKE LEARNING EASIER, Hrs FASTER, MORE EXCITING. ­ Add•oao,______Apt.__ EE Pleale ru1h new color talog plUI complete detall1 ,...,-..:;: Clly______Sl•I•------­ C0Ufl8 checked. Pleaao 1111 In ZIP coda for IHI.or .orvlce 0 OBLIGATION. O Chttcll for lnlc>rmallon o~ QI Biii 0 SALESMAN WILL CALL O Ch•1>k II lnlot111tod ONLY In Clau.room Tr1rn1no In Loo Ana•••• P l!'>o'l\01l1111r Cl#'>,_1 .....,"';...,., NEW NTS GR 2000 DIGITAL r­ .,. "'O COLOR TV. SOLID-STATE. 0 0 :z 0 0 > "'> 0 ~ "'~ 25" DIAGONAL. VARACTOR :l Cl QQ V> 0 0 ,., DIODE TUN NG. c: -2 "''iD' :E !." =r- > ;: - r (/) -n t""' (') g'Q' CD ;; al 2!. c: Pl 3 c:: :::;.: "'O ,, VI 0 ... )> 2­ ... 0"' :l II> {!} 6 .. 2 ~ ITI ar V> al ,. VI ~ ..... en -< ID ... n I :; VI ~ 0 ~ 0 !?.."' :c - ::0 w 0 - ITI ...... 0 ;c "ti t""' ~ :;: -- Q. en :> s::: :;.> ' New Fully Illustrated Color Cat81og Tells All "c ­.... About These NTS "Extr•" :!. ;; • Job Placement •Graduate Q. Consultation Association (/) ;; • Business Consulta- • Mechanics & ~ tlon Service Science Bulletins, i • Student Guidance Plus Much More ~ APPROVED FOR VETERAN TRAINING Clanroom Training Avallable Los ' "'O at Angeles < r- .. .., j; NTS oc:cupln a city block In aunnr, Soulhem Calllomla ~ 3 i with over a million dolla,. In lac Hiies devoted eac:lu· > 0 )> ;:; ~ alvely to techntcal tralnln9. Chack box on rave,... aide ;; !!. :. z 0 for detalla. ?= c: ~ ... ~ J> :~~ ;= . "'"'.... NATIONAL~SCHOOLS I ' TECHNICAL-TRADE TRAINING SINCE 1905 Resident and Home-Study School• ~ 4000 So. Figueroa St., Loa Ar111ele1, C1llf D0037 ~~'" ' HIGH FIDELITY SPEAKERS SOL.ID STATE STEREO AM FM RECEIVER AMPLIFIER

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NTS R.esident & Home Study Schools . . . p1.1tS mate inta yourtraini.Og,,so you get more out of 4000 Souto Figueroa St.,.Los Angeles, Calif. 90031 HE tuner is the " radio" portion tion, · caused by a signal reflecting T of your music system . Although from various structures and reaching most tuners cover both the AM and FM HOW TO the antenna from different directions broadcast bands (and proposed gov­ and at slightly different times. The ernment legislation will make this 11 tuner specifications related to low mandatory), the following comments multipath distortion are capture ratio apply specifically to FM tuners. "REA0 (the lower the better, with most good The tuner's function is to separate tuners under 3 dB and the best reach­ one desired signal from the many in­ ing 1 dB or less), and AM rejection tercepted by the antenna, amplify it (ratings in excess of 50 dB are good, millions of times, convert its fre­ and a few are as high as 70 dB). You quency modulation to an exact fac­ FM should be aware that no tuner can be simile of the original program, and (if it completely immune to multipath dis­ is a stereo program) subject the de­ tortion and that the best cure for this tected signal to a complex process and most other FM reception prob­ which separates it into left and right TUNER lems is a good directional antenna stereo channels. which can be rotated to obtain best Like amplifiers, most tuners tend to results. sound pretty much alike on ordinary The tuner distortion rating should program material. Many people place SPECS be well under 1%, and most good tu­ great store in numerical specifications ners are rated between 0.2% and 0.5% for such characteristics as sensitivity in mono, and about twice as much in and selectivity. Actually, neither of BY JULIAN D. HIRSCH stereo. Stereo channel separation var­ these is easy to reduce to a single con­ ies with modulating frequency, but is venient number that defines that as­ often specified at 400 Hz or 1000 Hz, pect of the tuner's performance. where it is greatest. Comprehensive Numbers are used, of course; but they signals of a few microvolts, and some­ ratings include a definition of separa­ are frequently misunderstood or mis­ times the highest possible tuner sen­ tion over a range of frequencies, such interpreted. sitivity is needed in such locations. In as 100 to 10,000 Hz . If the separation most urban and suburban locations, exceeds 20 dB over most of the audio Sensitivity. This refers to the ability the tuner receives from its antenna range, you can be assured of a satis­ of a tuner to receive a weak signal with hundreds or even thousands of mi­ factory stereo effect. Many tuners in acceptably low noise and distortion. crovolts from dozens of stations. all price ranges have 30 to 40 dB of The IHF Usable Sensitivity rating is separation over most of the audio most often quoted, although it does Selectivity. Clearly, high sensitivity band. not correspond to a really listenable is not likely to be an important tuner signal. Most good tuners have an IHF rating for the city dweller. What about Operating Ease. Many important sensitivity of less than 3 µ,V, and some selectivity? FM stations in any given tuner differences relate to their ease of are as low as 1.5 µ,V. Although in prac­ area are assigned to channels at operation, rather than their electrical tice it would not be possible to detect 400-kHz intervals (alternate channel performance. The tuning dial should any real difference between two tu­ spacing). If you are located close to a be legible and well calibrated. (Some ners whose sensitivities differed by a -powerful FM station and wish to re­ tuners, even high-priced units, are dif­ factor of two (all else being equal), ceive a far-off station only 400 kHz re­ ficult to set accurately to a known fre­ there is a tendency to make much of moved, you will need high alternate­ quency because of inadequate dial differences of a few tenths of a mi­ channel selectivity. Most FM tuners calibration.) The tuning " feel" should crovolt, a quite insignificant amount. have selectivity ratings between 45 be smooth and positive. Tuning indi­ More meaningful is the 50-dB Quiet­ and 60 dB, which is generally ade­ cators, whether meters or lights, ing Sensitivity rating included in a quate for interference-free reception . should give an accurate indicati.on of proposed IHF tuner standard, but not If you have a " problem," there are correct tuning. lnterstation-noise rriut­ yet in wide use. Our test reports in some tuners whose alternate-channel i ng circuits should be free from bursts POPULAR ELECTRONICS do include it, selectivity is 90 dB or more. They are of noise as one tunes through a station however. This is usually in the range of expensive, but well worth it if you need (although many are not). All of these 3 to 7 µ..V and represents the weakest their special qualities. characteristics are easy to judge for mono signal that can be received In strong-signal areas, some tuners yourself and require no technical without excessive background hiss. are subject to spurious responses knowledge. For stereo reception , all these sensitiv­ -signals appearing on the dial in un­ There are several tuners with digital ity figures should be multiplied by a expected places and sometimes inter­ frequency readouts instead of the factor of ten, which may explain why fering with a desired signal. The rele­ usual slide-rule dial. This eliminates stereo sensitivity ratings are not vant ratings-image rejection, spuri­ any problems of dial calibration but widely publicized! ous rejection, i-f rejection-are also adds appreciably to the cost of the Of course, these sensitivity numbers expressed in decibels, with the higher tuner. Compensating for their higher have no absolute meaning to the con­ numbers being better. prices is the fact that most digital sumer who cannot know the actual re­ tuners also have above-average per­ ceived signal strengths in his area. In Capture Ratio. A major cause of dis­ formance in most other respects relat­ rural locations, one can indeed find torted FM sound is multipath recep­ ing to high fidelity. ~ 68 POPULAR ELECTRONICS OST experimenters have a Identifies leads on unknown Mdrawer full of unidentified tran­ sistors which a r e of littl e u se unless transistors, indicates Pf\lP or NPN the leads and type (pnp or npn) can be determined. Actually, that's the polarity, anti shows up bad devices only really important information needed to apply a transistor in a circuit-assuming it is " good" to begin with. Of course, it's nice to BU\\.1> TME. TRANSISTOR IDENTOMETER

BY JOHN T. BAILEY

know what the transistor's beta is, but this is not essential in many applica­ tions. The ldentometer was designed to provide a quick check of a transistor's leads and type. It operates on the basis that bipolar transistors will operate, but poorly, if the emitter and collector leads are interchanged without also reversing the power supply. Since a transistor has three leads, it is possible to connect them in six different ways. With a transistor plugged into the test circuit, the ldentometer has a switch to make the six different connections. When the right one is selected, an indicator light comes on. The light also tells whether the unit is npn or pnp.

Circuit Operation. A schematic of the circuit is shown in Fig. 1. Note that T1 has two secondaries, one serving as the power supply for the 01 -LED1 and 02-LED2 circuits and the other for the unknown transistor. Transistor 01 saturates when the upper secondary voltage is in the positive half cycle and its base is positive. Transistor 02 saturates when its collector has a negative voltage and its base is negative. The two transformer secondaries must be in phase as shown by the small dots at terminals 1 and 3. The circuit is equivalent to an exclusive OR logic device, which has an output only when the two inputs are at different levels. The high or low signal requirements are provided by the transistor being tested and the instantaneous polarity of the ac line at the moment. The combination is one polarity for npn transistors and the opposite polarity for pnp types. 69 02 IN4001 PARTS LISTS Tl SI DI, D2----:IN4001 diode D3, D4-1N914 diode LEDi, LED2-Light-emitting diode (Calec­ tro K4-559 or similar) Ql-HEP736 transistor Q2-HEP715 transistor Rl-R3-1000-ohm, ~-watt resistor R4-I8,000-ohm, ~-watt resistor Sl-Spst switch S2-3-pole, 6-position rotary switch (Mal­ lory 3236.J or similar SOI-Molded transistor socket Tl-12-volt, 300-mA filament transformer (Radio Shack 273-1385, modified per text) R4 SOI Misc.-Plastic case (Radio Shack 270-231), 18K Insulated miniature alligator clips (red, green, and yellow; Radio Shack 270-378), · knob with pointer, line cord, mounting S2 hardware, press-on type, etc. ,rl r. [n GREEN Fig. 1. Transisto1· being tested I I I I I is plugged into 801 or connected REo6??= l I J I l l l to color-coded alligator clips. YELLow,..-:::::;2= 1 1 1 1 1

This distinction provides the type totype and use the pc boards shown then be spaced three ori each side, on identification. in Fig. 2, certain mechanical modifi­ 3/a-in. centers. With the correct phasing of the 3-4 cations must be made to two of the Wind 46 turns of #34 enamelled secondary of T1, the exclusive OR components. Transformer T1 must wire around the original core. There signals are accepted by the LED have i!s four terminals cut to a size is enough room to do this, although it driver that can react to a compatible that can fit into the pc board. As will take a little patience. Be sure that signal during its half cycle of the ac. shown in Fig. 3, two more tabs must the new winding is wound in the same Diodes 03 and 04 prevent slight be added to terminate a new winding. direction as the 12-volt winding differences in the voltage levels from The molded plastic form of this already on the transformer to ensure turning on the drivers. transformer allows adding the two correct phasing. (Don't scrape the new terminals (3 and 4 on the enamel off the wire.) If you should Construction. To duplicate the pro- schematic). The six terminals will wind the new secondary the wrong 1--­

RED 52,Y

YEL.*' 52,X •2 52,3 GRN

52,2 g L.ED2,K L.ED1,A g Fig. 2. Foil pattern for main pc board is at left, with component layout at right. Foil pattern above is for rotary switch.

70 POPULAR ELECTRONICS way, it is easier to route the ends to the correct terminals than to start Simple over or modify the pc board. The terminals of S2 must be Squelching modified as shown in Fig. 3 so that · the switch will fit the pc board as Circuit~ shown in Fig. 2. .a.Or Now you are ready to assemble the circuit on the main board as shown in StereoFM Fig. 2. The front panel is marked as shown in the photograph with the six Tuners switch positions identified. Install S01 and mount the LED's in small rubber grommets, properly identified. BY LAWRENCE N. DWORSKY ANY inexpensive stereo FM If the tuner being used has an ex­ M tuners have no automatic ceptionally low output impedance " squelch" to eliminate between-sta­ -less than 600 ohms or so-the be­ ADDED SECONDARY 46T #34 ENAMEL tion hiss. However, they invariably tween-station muting may be insuf­ have a stereo indicator lamp that can ficient with this setup. In this case, a ~CLIP~FF be used to trigger a very simple 100-ohm resistor placed in each out­ squelching circuit like that shown in put line of the tuner (see phantomed

BEFORE AFTER the schematic. portion of schematic) should remedy SWITCH LUG The add-on squelch circuit shown the problem. Since most amplifiers DETAIL employs an inexpensive photo Dar­ have a relatively high input imped­ Fig. 3. Add a winding and lington amplifier (HEP1001), operat­ ance, these resistors shou Id have no terminals to the transformer ing with its base connection "float­ effect on system performance. and alter switch lugs as shown. ing". The Darlington amplifier switch­ No power switch is needed with the Then mount the switch on the front es from a very high resistance in dark­ add-on squelch circuit because bat­ panel. Connect the larger board to it ness to a very low resistance when tery drain is very low. Even when with spacers. Note that the large illuminated by relatively low light operating at full capacity, the drain is board has a small spacer supporting levels. When the photo transistor is less than 10 µA. So, the battery wi II last it from the holed rilled near the center switched to low resistance, essen­ ju st about its shelf I ife with power con­ of the rotary switch board. tially the supply voltage from the bat­ ti nuously on, which eliminates the Drill three small holes for the tery is applied across the gate-source bother of having to remember to turn colored test leads and put grommets terminals of both HEP 802 FET's. This on an extra power switch. in the holes. The leads are terminated pinches off the FET's and causes them When installing the squelch circuit, with color-coded insulated alligator to present a very high source-drain re­ use only shielded audio cable to make clips. From the top of the panel, the sistance across the outputs of the the hookups between tuner, squelch­ lowest test lead (green) is on a line tuner, effectively doing nothing. er, and amplifier. Also, mount the Dar­ from the emitter terminal on S01; the When there is no light present, the lington amplifier as close as possible center lead (yellow) is the base; and photo transistor presents ahig h resist­ to the stereo indicator lamp in the the upper lead (red) is the collector. ance to the gates of the FET's. The tuner. This transistor is very sensitive; source-drain resistance of the FET's so, care must be taken to insure that it Operation. Connect the three therefore drops to about 200 ohms, " sees " light from only the stereo indi­ color-coded test leads to the u n­ effectively short-circuiting the outputs .cator lamp and not from any other known transistor in any order, turn on of the tuner. light sources. ~ the power, and rotate S1 until one of the LED's illuminates. Make sure that this only occurs at one position. The position of the switch will then identify the leads and the LED will indicate the type. If the transistor being tested is not good (either open, shorted or leaky), neither indicator may come on or one or both may light at more than one switch setting. The ldentometer will not check FET's, nor will it work "in circuit." When checking power transistors, particularly germanium types, there may be some unpredictable results due to the high leakage current associated with these transistors. ~ JA,.UARY 1975 71 easily bridge open switch contacts of ,, MAC'S SERVICE SHOP a radio or TV receiver. Most people don't understand this. " What kind of damage does light­ ning do? " IGHTNING DAMAGE " Mark Twain remarked that one th ing you could lie about and get away with was to tell something you heard a INSURANCE JOBS parrot say. Lightning stories are like that. No one can prove you 're lying. By John T. Frye, W9EGV I've seen lightning strike a horizontal antenna and reduce itto a line of little copper beads in the grass below. " T'S TIME we furthered your edu­ dence that the failure was caused by When a conductor carries a heavy cur­ I cation by discussing light­ lightning, (2) authorizes a repair of the rent, forces are developed by the ac­ ning-damage insurance jobs that set, or (3) because the cost of repair is companying magnetic field that tend come into the shop, " Mac announced prohibitive, makes some cash or re­ to crush the conductor. This is called to Barney his assistant, during their placement arrangement with the in­ the 'pinch' effect. Another time I saw a afternon Coke-break. sured. The company pays for the esti­ rubber-covered copper wire that had " A man can 't even enjoy a Coke mate in the last two cases; the cus­ been hit by lightning and reduced to around here without having it laced tomer pays in the first. At any rate, the a rubber tube with no wire inside at with knowledge, " the red-headed bill is made out in triplicate: one for all. Stranger still, the rubber insulation youth grumbled, "but go ahead-if the customer, one for the insurance seemed to be intact and hardly you must. " company, and one for our files. The scorched. More common effects in­ " That's what I like: an enthusiastic customer pays us, and we give him clude the fragmentation of line bypass listener," Mac said , lighting his pipe. two receipted copies of the bill. He capacitors, melted power switch con­ " There are three entities involved in turns one over to the insurance com­ tacts, fused conductors on pc boards, this kind of a job, and each must be pany, and they send him a check." vacuum tube envelopes shattered, considered : the owner of the dam­ " Why might a person think lightning aged electronic equipment, his insur­ had damaged his equipment?" ance company, and the service shop " Such circumstantial evidence can called upon to assess the nature and vary all the way from a coincidence in extent of the damage and possibly to which the set would not operate im­ repair it. Let's run quickly through the mediately after a heavy thunderstorm chronology of such a job;then we'll go to much stronger evidence in which a back and discuss interesting features. ball of fire comes out of the TV set at ADJUST N0. 4 OR " First, an insured who thinks light­ the same time there is a snap of light­ LARGER ning has damaged his radio, TV , ning from a nearby stroke, followed by TO GROUND hi-fi, amateur station, CB transceiver, smoke curling out the rear of the etc., should promptly report this to his cabinet." SAME SPACING AS FEEDERS insurance agent, who will instruct him 'That last rem inds me of Thoreau 's to get an estimate of the damage from remark: 'Some circumstantial evi­ Fig. 1. A spark gap arrestor to protect ham antenna is easily made. an established service shop. (That dence is pretty strong, like finding a doesn't mean the insured's brother­ trout in the milk.' How does lightning ruptured filter capacitors, shorted in-law who tinkers around with elec­ usually reach the equipment?" windings in power transformers, an­ tronics in his spare time!) At the shop, " In the case of a receiver attached to tenna input coils of radios and TV sets a technician carefully examines the an outside antenna, the stroke or in­ badly charred, flash burns on the equipment to see if the set failure was duced voltage surge can come in on chassis in the vicinity of line cord tie­ caused by lightning, the extent of the the feedline, but more often it enters points or the power switch, and tubes. damage, and the probable cost of re­ via the power line. A bolt doesn 't have with burned out filaments. These are pairing the set. This information is re­ to strike the line for this to occur. All it some of the things the ad juster will layed to the insurance agent, directly has to do is strike in the vicinity. After expect to see. " or through the owner, and the agent all, the current of lightning strikes has " I imagine the action the insurance calls an adjuster to look at the set. It been esti mated to be as high as company takes depends a lot on the may be a few days before the adjuster 200,000 amperes , with 15,000 to policy the owner has. " calls at the shop; but when he does, he 20,000 amperes being an average " Right. The usual home owner's will want the technician to show him value ; and the voltages producing the policy comes in a variety of types, in­ hard evidence that lightning did the strike are estimated to be as high as cluding various deductible amounts damage ; so all such evidence should 100,000,000 volts. Lasting only mi­ with matching premiums. Naturally, be carefully preserved for his inspec­ croseconds, such a strike produces a the higher the deductible the lower the tion. tremendous field that induces a volt­ premium. TV, amateur, and CB anten­ " The adjuster reports to the insur­ age surge on the primary of a power nas, rotators, and towers are not ordi­ ance company, which, based on his line that can leap across to a trans­ narily covered by policies that are writ­ recommendation , either (1) denies all former secondary and enter the house ten to cover the house, garage, and responsibility due to a lack of evi- through the ac wiring. This surge can household goods. Even then, with 72 POPULAR ELECTRONICS such a policy, TV sets, radios, and cause I intend to ca.II things exactly sistance increa:>es until the voltage hi-ti's are only covered for their actual as I see them. Invariably, he then drop across it is sufficient to stop the cash value. The guy who has never backs off." arc. Various resistance and gap types read his policy carefully may be very "What do you think is the best in­ of lightning arrestors are manufac­ chagrined to discover the total loss of surance policy?" tured for use with telephone lines, co­ his beloved but ten-year-old hi-fi does " That's easy: prevention. You rarely axial cable, twin-lead, etc. not entitle him to a brand-new stereo recover your entire loss through in­ " But remember I said most damage system at the expense of the insur­ surance; so the best thing to do is try from lightning occurs when a surge ance company. He may do well to re­ to protect your equipment from light­ comes in on the house wiring. That's cover the cost of a new stereo car­ ning damage. You could, of course, why I think it is an excellent idea tridge. follow the practice observed in the old to install a secondary service light­ French provinces and keep some ning arrestor, such as G.E. Model wood from a lightning-struck tree 9L15CCB007, called a Home Light­ under your bed , secure in the belief ning Protector, right at the service en­ you're fully protected because 'light­ trance. Otherwise, pull the plugs on all ning never strikes twice in the same electronic equipment when you're place'; but I'd suggest you employ going to be gone for several days or tl7VAC STEP·DOWN more scientific methods. Start by mak­ when you 're home and a thunder­ POWER TRANSFORMER ing sure your house wiring is properly storm is building." grounded and protected against over­ " Do you think a high antenna tower loads with fuses or circuit breakers. invites lightning damage to the Install U.L.-approved arrestors on all home?" TV lead-ins, antenna rotator control Fig. 2. In pmver-line arrestor, wires, and coax feed lines. Ground current is reduced by resistor. metal towers or metal masts mounted " But there's another way to go. If he on poles or other wooden supports. has ham, CB, or hi-fi equipment worth Make a good common ground. If you $500 or more, he can insure it for full don 't know how-most people replacement value with a separate pol­ don't-order "Lightning Protection icy usually labeled a 'perso·nal line Code 1968," NFPA No. 78, from the floater' or an 'inland marine floater.' National Fire Protection Association, Then, if his equipment is destroyed, 470 Atlantic Avenue, Boston, MA the company will pay enough to buy a 02210, for a postpaid price of $1 .37. " ' ...... __ _ new system comparable to the one he " How do lightning arrestors work?" had before. Such policies cost from 'There are many types, but all are ------80¢ to better than $2 per $100 of de­ intended to do one job: carry a heavy clared value per year, depending on surge of lightning-induced current in Fig. 3. A metal antenna tower, the individual company and the item a· conductor safely to ground, while properly grounded, provides a cone insured. Jewelry, cameras, tools, serv­ leaving that conductor virtually dis­ ofprotection for the house. ice instruments, and similar equip­ connected from ground at all other "Quite to the contrary, if the tower is ment in the home can be insured with times. Let me sketch a couple of metal and properly grounded or has these policies." . common types. Shown in Fig. 1 is a the metal mast properly grounded, it " Seems to me the technician is homemade spark gap arrestor for use actually provides a cone of protec­ pretty important in this operation." on the open-wire feeders of a ham an­ tion as shown in Fig. 3. Note that the That he is. Actually I do many insur­ tenna. Gaps are spaced just wide apex of the cone is at the top of the ance jobs here without ever seeing an enough notto arc with full power from grounded antenna, and the radius of adjuster. Local agents know me, and the transmitter, but voltage from a the base is equal to the height of the they also know the average adjuster nearby discharge will start the arc that tower. A direct strike of lightning to is unqualified to assess damage to carries the heavy current safely to any object inside this cone is very un­ sophisticated electronic equipment. ground. When the surge subsides, the likely." They're content to use my report as arc stops. "All right, let's recapitulate: quiz the basis for settling the claim. I'm "Things are different when the con­ your insurance agent and read your sure this arrangement prevails in ductor normally carries heavy current policy carefully to see exactly what many other communities, and it puts a and high voltage, as does a power line kind of protection you have for your lot of responsibility on the technician, primary. Once the arc is started by electronic equipment. To protect that especially when the equipment be­ lightning, the follow-current from the equipment, use lightning arrestors on longs to a long-standing customer generator would keep it going until all leads entering the house, including who feels 'taking' an insurance com­ the arc electrodes were melted . The the power leads. Make good grounds pany isn't really stealing. When one of arrangement in Fig . 2 prevents this. and bond them together. Pull plugs these starts hinting he wants me to The nonlinear thyrite resistor 'has during storms or when you 're going to declare his equipment a total loss a resistance which decreases expo­ be away from home, and don't try to when it isn't, or to say the damage was nentially with increasing current. con the service technician into help­ caused by lighning when there's no When carrying the heavy discharge ing you defraud the insurance com­ evidence to support this, I suggest that current, it is a virtual shortcircuit; but pany. If he goes along with that, he 'll he take his set to another shop be­ with the lower follow-current, the re­ cheat you, too!" ~ JANUARY 1975 73 It takes more

Bell & Howell Schools introducesleamabout three As you put the set together, you'll discover fascinating learn-at-home programs featuring how advanced integrated circuitry works, how to some of the finest equipment available as your trouble-shoot it and much more. Upon completion "teachers". Choose the program you prefer­ of the program you'll have gained the specialized then mail card for free details today! occupational skills to service color 1V's plus the principles that you can apply to repair a variety of Experience is the best teacher, without a doubt. home electronic equipment. And you'll have the And when it comes to learning electronics, we feel it's foundation to understand and work with new product hands-on experience with state-of-the-art equipment applications as they're developed, too! that counts the most. That's why with Bell & Howell Schools' learn-at-home programs you work with some of II. Use professional communications equipment as you delve into Communication Electronics • the most up-to-date equipment. Equipment that's being used today-and will be used tomorrow. So the skills and Here's how to pick up skills in the Vital field knowledge you acquire will be useful for years to come. of two-way radio, widely used in public safety, marine, Of course, with all our learn-at-home programs industrial and transportation areas. Bell & Howell you'll have plenty of lab manuals and basic principles to Schools Communication Electronics Program can work with. And you'll also get exciting "teachers" to help help prepare you for the FCC licensing exam, right make electronics come alive . . . through to 1st class radiotelephone operator. And teach you skills in two-way radio, radar or commercial Lab Starter Kit gives you hands-on experience broadcasting. with the very first lesson. For a refundable deposit, you get to use the We get you started with the basics in an exciting special two-way radio equipment lab way! At the very beginning you get a fully-assembled featuring an FM transceiver, volt-ohm meter as well as design panels, modular frequency meter, and connectors, experimental parts and battery. So you don't modulation meter. All just read about electronics principles, you actually see regular, first-rate commercial them at work! grade test equipment. You build your own Electro-Lab '°B- electronics training system. Whatever program you choose, you get your own home laboratory including oscilloscope, digital multimeter·and design console to give you actual experience in wiring, soldering, assembling, testing, trouble-shooting and circuit analyzing. I. Learn new skills in the field of Home Entertainment Electronics including building the new generation color TV . What better or more exciting way to learn digital electronics! Once you have the basics under your belt and get into color theory and servi ce, you'll build a 25" diagonal color 1V and probe into the digital technology behind digital channel numbers that flash on the screen . .. a digital clock that flashes the time to the second and an automatic channel selector.

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74 POPULAR ELECTRONICS than books to

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JANUARY 1975 77 varied the drive level to maintain a constant 90-dB sound-pressure level (SPL) at a distance of 1 meter from the woofer, the distortion was somewhat Product higher than we have measured on some other speakers of the same size, but it was not audible on program Test Reports material. The tone-burst response was fairly good. There were no signs of severe ringing or generation of spurious fre­ quencies throughout the operating TECHNICS BY PANASONIC MODEL T·200 SPEAKER SYSTEM range of the system . Efficiency was (A Hirsch-Houck Labs Report) moderately low, as wou Id be expected Compact, inexpensive system with room-filling soun.d. of an acoustic-suspension design. An input of 1 watt in the midrange pro­ approximation, of its total energy out­ duced a 90-dB SPL at a 1-meter dis­ put over the frequency range. Averag­ tance . This corresponds to about ing and warble-tone measurements 80-dB SPL in the normal listening area were used to minimize the effects of of a typical room, which is about as standing waves. At frequencies lower loud as most people would care to lis­ than about 300 Hz, close microphone ten to music in their homes. spacing was used, and the two test The electrical impedance of the sys­ curves obtained were joined together tem was 5 ohms at 20 HZ and between to provide a composite frequency­ 100 and 200 Hz. It peaked at 18 ohms at response curve. the 62-Hz bass resonance point. At The response of the woofer was frequencies higher than 1000 Hz, the notably smooth, with a resonant peak impedance was typically 15 to 18 of about 3.5 dB at 75 Hz and no sign of ohms. irregularity up to several hundred hertz. The tweeter also had a rather User Comment. The general shape flat response curve (although it is of the measured response curve for normal to find some irregularity at the T-200 was confirmed by our simu­ high frequencies with the measure­ lated live-versus-recorded listening HE Technics Model T-200 is the ment methods we used). Its output fell test in which the T-200 was used to T least expensive of a new series off smoothly at frequencies beyond imitate the sound of a specially re­ of loudspeaker systems from 10,000 Hz , with no sign of a peak corded program played through a ref­ Panasonic. It is a compact system that throughout its entire range. The over­ erence speaker, our "live" orchestra. measures 21 3/4 in. by 12 in. by 101/2 in. all response was a very good ±4 dB The T-200's midrange and highs were deep (55.2 x 30 .5 x 26 .7 cm) and from 45 Hz to 14,000 Hz. virtually perfect, but there was a weighs slightly less than 30 lb (13.6 The bass distortion at a constant slightly full quality in the lower mid­ kg). The oiled walnut cabinet con­ 1-watt drive level was between 3% and range and upper bass range. This ap­ trasts with an attractive sculptured, 5% from 100 Hz to 60 Hz. When we peared to correspond with the fact acoustically transparent grille that is available in either blue or brown. The two-way system contains a 10-in. (25.4-cm) acoustic-suspension woofer that crosses over at 1800 Hz to a 13/4-in. (4.45-cm) cone-type tweeter. The rated dispersion angle of the tweeter is 120° in both the horizontal and vertical planes. A switch is pro­ vided on the rear of the cabinet to permit the tweeter level to be set for normal or 3 dB attenuation. (Flattest overall response is obtained with max­ 20 50 100 200 500 lk 2 k imum tweeter output.) The system has FREQUENCY - Hz a rated nominal impedanceof8 ohms. The retail price of the Technics ~f Model T-200 speaker system is $99.95 . iv Laboratory Measurements. The response of the speaker system was measured in a " normal " listening room by a method that yields a good 300 Hz 1800 Hz 7000 Hz 78 - POPULAR ELECTRONICS 50 ting the original sound in an A-8 com­ 30 parison. The highs were obviously

20 peak-free and very well dispersed. (/) ::; Listening to this speaker system, :i:: 0 10 8 one is apt to find it difficult to bei'ieve that the sound is coming from an in­ 5 4 expensive compact system. It gives a 3 room-filling sound suggestive of a much larger system and provides ex­ ceptionally good musical balance and overall smoothness. The T-200 illus­ •oooo' trates most effectively how the proper FREQUENCY (Hz) combination of conventional drivers and crossover components by a that the average woofer level was a " shelf" response cut) was applied at knowledgeable designer can produce few decibels higher than was the aver­ frequencies below 1000 Hz with an a total sound character that is greater age tweeter level. octave-band equalizer, the speaker than the sum of its parts. When a 3- to 4-dB attenuation (a system did a near-perfect job of imita­ CIRCLE NO. 65 ON READER SERVICE CARD

PIONEER MODEL RT·1011L STEREO TAPE RECORDER tional flexibility in adapting the re­ (A Hirsch-Houck Labs Report) corder to any type of tape. They Logic-controlled recorder handles 10 %-inch reels. separately control recording bias and equalization. Each has positions shut-off switch in the event of tape for STD (standard) and LH (low breakage and when the tape runs out. noise/high-output) tape formulations. Two large illuminated meters indi­ A table in the comprehensive instruc­ cate both recording and playback tion manual provided with the.record­ levels. The meters monitor the line er suggests switch setting combina­ · outputs so that the playback indica­ tions for many popular tapes. Alterna­ tions vary with the setting of the tively, optimum conditions can be de­ playback level controls. Located termined by recording and listening. above the meters is a red light that The last lever switch connects the comes on whenever one or both line outputs to either the source channels is set to the RECORD mode. (input) signal or to the playback Below each meter is a standard jack amplifier's outputs. for 600- to 50,000-ohm dynamic mi­ Concentric control knobs are pro­ crophones. vided for independently adjusting the Locking pushbutton switches con­ recording levels in the two channels. trol ac power, tape tensioning for 7-in. One pair of controls is for the mi ­ HE U.S. Pioneer Electronics (17.8-cm) and 101/2-in . (26.7-cm) tape crophone inputs, while the other is for T Model RT-1011 L stereo tape re­ reels, and tape speed. Other pushbut­ the line inputs. A third pair of concen­ corder features three motors, three tons are labeled REC, PLAY, REWIND, FAST tric controls permits the playback heads, solenoid-operated transport, FORWARD, and STOP. For easy identifica­ level to be adjusted in each channel. and 71/2 and 33/4 ips (19.05 and 9.53 tion, the REC button is red, .while the A stereo headphone jack is located cm/s) operating speeds. This quarter­ STOP button is larger than the others. on the recorder's front panel.,The line track recorder is designed to accom­ Although the pushbuttons energize inputs and outputs and a DIN socket modate tape reels measuring up to solenoids, they are designed to that repeats the two are located on the 101/2 in. (26.7 cm) in diameter. The mechanically lock into position to rear of the recorder. transport is " logic controlled" so that permit the recorder to be set up in The recorder can be operate<;! verti­ any operating mode or speed can be advance for recording. When line cally or horizontally. It measures 17. in. selected from any other without hav­ power is later applied by an external high by 16 7/8 in. wide by 8 15/16 in. ing to first press the STOP button. Yet, clock timer,the deck goes directly into deep (43.2 x 42 .9 x 22.9 cm) and the tape is fully protected against its recording mode. weighs 49 lb (22.3 kg) . It comes with breakage and spilling. Five lever switches supplement the walnut side panels, a 101/2-in . metal pushbuttons. Two place the channels reel , and two reel-hub adapters for General Description. The record­ individually into the recording mode professional-size reels with large er's tape loading procedure is simpli­ when the REC button is pressed. This is center holes. fied by a guide roller arm that locks out a safety feature that prevents acciden­ The retail price of the Pioneer Model of the way when it is moved to its limit tal tape erasure. It also serves as a RT-1011 L stereo tape recorder is so that the tape takes a straight-line means of recording on one channel $599.95. path across the heads, over the cap­ while playing back through the other stan, and over a tensioning arm as it for echo and sound-on-sound (the lat­ Laboratory Measurements. Using goes to the take-up reel. The tension­ ter requiring external patching). Ampex test tapes , we found the ing arm also serves as an automatic Two more levers provide excep­ playback equalization of the tape re- JANUARY 1975 79 prise, the flutter was reduced when the guide roller arm was locked in its loading position. (It normally plays an important part in reducing flutter.) The flutter measurements were then 0.08% and 0.12% respectively. Wow was the residual of the test tapes, measuring 0.01% to 0.02%. The tape transport operated smoothly and appeared to be fool­ proof. When going from either fast speed to PLAY, the tape came to a stop in about a second and paused for 2 or 3 seconds before going into play. The FREQUENCY (Hz) manual explains how the PAUSE con­ trol can be used to eliminate even this corder to be very accurate at both loaded at 70 mV. This should be quite small delay if desired. speeds. It was within ±0.5 dB from 50 adequate for most recording situa­ The headphone outputs had very Hz to 15,000 Hz at 7V2 ips and within tions. good volume levels, even with 200­ ±0.8 dB from 50 Hz to 7500 Hz at 3 3/4 A standard Dolby level tape played ohm high-impedance phones. ips. (These are the frequency limits of back with a full-scale +3-dB meter in­ the test tapes.) dication. The meters were somewhat User Comment. Despite an ability to We used 3M No. 207 tape for the slower in responding than are true VU accommodate 10V2-in. reels, this is balance of our tests. We measured the meters. They indicated 65% of their very much a home tape recorder-an record/playback response with all four steady-state values on 0.3-second outstandingly fine one. In ease of load­ combinations of switch settings. Al­ tone bursts as compared to 99% for a ing and handling, it is about as simple though the differences were slight, we true VU meter. and straightforward as any machine concluded that the LH bias and STD At a 0-dB recording level, the we have used. Its frequency response, equalization settings yielded the flat­ playback distortion was 1.0% at 7V2 ips distortion, and noise levels are among test overall frequency response. and 1.2% at 33/4 ips. To reach the stan­ the best we have measured and would Using a-20-dB recording level at3 3/4 dard 3°/o reference distortion level, it do justice in most respects to any pro­ ips, the overall response was within was necessary to record at+12 dB (far fessional recorder. ±2.5 dB from 20 Hz to 13,500 Hz. At a off the meter scales) at either tape Due to the calibration of the deck's 0-dB recording level, tape saturation speed . Referred to this level, the un­ meters, it is eminently practical to (expected at this speed) caused a weighted noise was -62 dB at 7V2 ips. maintain average music recording sharp drop-off in response beyond With IEC A weighting for better corre­ levels near the 0-dB mark. The meter 7000 Hz. At 7V2 ips, the response at the lation with subjective effects, the pointers can be permitted to swing to -20 dB level was a very flat 2.5 dB from noise was -70.5 dB. It is interesting to full-scale and beyond on peaks with­ 20 Hz to 24,500 Hz. It was within ±1 dB note that the S/N ratio at 33/4 ips was out serious risk of over-recording. from 25 Hz to 21 ,000 Hz. Saturation only 0.5 dB lower than at 7V2 ips. At Needless to say, the deck did a flaw­ was less of a problem at higher record­ maximum gain through the mi­ less job of recording from phono­ ing levels at 7V2 ips. Hence, the 0-dB crophone inputs, the noise level in­ graph and tuner sources as well as of response did not begin to fall off ap­ creased by a negligible 3 dB. playing back commercially recorded preciably until we reached 12,000 Hz. The tape speeds were 0.4% fast at tapes. At a surprisingly reasonable The line inputs required 43 mV for a 7V2 ips and 0.4% at 33/4 ips. In fast for­ price, the Pioneer Model RT-1011 L of­ 0-dB recording level. This produced a ward and rewind, an 1800-ft (550-m) fers an impressive combination of maximum playback output of 0.5 volt. tape passed in 84 seconds. The un­ high performance and operating ver­ The microphone sensitivity was 0.18 weighted rms flutter was 0.12% at 7V2 satility. mV for 0 dB, while the amplifiers over­ ips and 0.16% at 33/4 ips. To our sur­ CIRCLE NO. 66 ON READER SERVICE CARD

HEWLETT-PACKARD MODEL 5381A FREQUENCY COUNTER ity are more critical when complex fil­ Seven-digit, laboratory-grade instrument operates to 80 MHz ters are involved since they don't work modern electronic systems-filters in properly unless they are tuned " on the

. ~ ~ ~. stereo rec.eivers and speaker cross­ head." overs; SSB, RTTY, and SSTV filters in Although there are many reliable -: ::. El [I '-/ S : ' ham gear; digital systems in frequency frequency counters, it is nice to see - '~ synthesizers and calculators-a good that one more big name (Hewlett­ .-::•. I ... frequency counter is an important Packard) has entered the relatively f! . ' (~·:.... item to have on the electronics work­ low-cost market with their Model a!'D!>lhl• eQlo\ Ol:>f'l'l!:OUFNCY CCIUl11 i R 11•, Kn•• ·~-:~ Joll. 1) bench. A frequency counter is essen­ 5381A Frequency Counter ($249). ~~ ~*~~ -~ """ ~~.~-- ~ tial for checking the accuracy of dials This 7-digit (LED) laboratory-grade on r-f and a-f signal generators. instrument has a frequency range of ITH the increasing number of Though they are usually "within the 10 Hz to 80 MHz (which means it can W frequency sensitive circuits in ball park," dial accuracy and resetabil­ be used in the CB and ham ranges). 80 POPULAR ELECTRONICS Sensitivity is 25 mV up to 20 MHz and wide, and 9.75" deep. It weighs 4.75 lb not have to worry about the accurate 50 mV to 80 MHz. Accuracy is±1 count and has a built-in ti It stand. settings on the various frequency plus or minus the time-base accuracy. generators since the excellent accu­ The time base uses a 1-MHz crystal User Comment. We had the oppor­ racy of the 5381A, even with 5% to 8% that ages less than 0.3 ppm/month, tunity of using the 5381A for several power reductions, enabled us to make ±10 ppm from 0° to 40°C, and ±1 ppm weeks on a variety of electronic critical adjustments. for a·103 line voltage variation. equipment. After aligning a number of A number of CB rigs have been Gate times can be selected manu­ SCA traps and half a dozen or so filters checked and aligned with each other, ally and the resolution is 10 Hz at the in SSB and SSTV rigs, and checking a after which, communication between 0.1-second gate time, 1 Hz at the number of countdown circuits in digi­ units was improved due to the closer 1-second gate time and 0.1 Hz at the tal projects, we really got to like the r-f alignment. The tone-alert acces­ 10-second gate time. The input impe­ look of the seven-digit, easy-to-read sories were also re-aligned so that the dance is 1 megohm shunted by 50 pF. display. In the MHz mode, reading the systems worked as they did when Even at the mostsensitive settings, the value down to three decimal places brand new. input to the counter will handle up to was easy, while in the Hz mode, reso­ For use at even higher frequencies, 200 volts (peaks ac plus de) without lution was 0.1 Hz. Hewlett-Packard also has a Model harm. The 5381A was in regular use in the 5382A, a 225-MHz version, which Physically, the 5381A is quite pleas­ shop even through the so-called costs $450. ing in appearance, with a clean, un­ "brownout" days when the power line cluttered look. It is 3.5". high, 6.25" had considerable variations. We did CIRCLE NO. 67 ON READER SERVICE CARD

TRAM DIAMOND 40 AM CB TRANSCEIVER and 70 and 90 dB i-f signal rejection at Has output circuit protection, SWR bridge and noise blanker 10-10.04 MHz and 455 kHz, respec­ tively. Spurious-signal rejection mea­ and weighs 6 pounds (2.7 kg). It retails sured 55 dB minimum. for $209.95. The noise blanker is a parallel-gate setup in which an IC is used at the The Receiver. According to our front end and for gating the output of tests, the double-tuned receiver has the second mixer. It can be turned on excellent sensitivity and selectivity. and off while simultaneously shifting The sensitivity measured 0.3 µV for 10 in and out of the circuit a series-gate dB (S + N)/N at 30% modulation and type a-f automatic noise limiter (anl). 1000 Hz. Adjacent-channel rejection This noise-reducing setup proved to was nominally 60 dB, while good be extremely effective. It attenuated communication quality was main­ noise pulses of 30 to 40 dB above a HE Tram Diamond 40 is a 23­ tained with a 6-dB overall bandpass of 0.25 µV signal down to near inaudibil­ T chan nel crystal-synthesized 450 to 2400 Hz. ity in the presence of the signal. Its use mobile transceiver designed for AM The bipolar r-f input amplifier is drops the overall gain on weak signals operation on the Citizens Band . equipped with shunt diodes that serve by 4 to 6 dB, but the sensitivity­ Among its special features are a as protection against overloads. The versus-S/N ratio is unaffected. microphone-gain control, final­ first conversion to a 10.0- to 10.04­ (A noise limiter is simply an audio­ amplifier protection circuitry, built-in MHz i-f is accomplished with the aid of frequency signal peak clipper. Usually SWR bridge, switchable noise blanker a FET mixer. A bipolar-transistor set to provide 100% modulation, it (in addition to the usual AM-type noise mixer is used for the second conver­ clips any signal level that exceeds that limiter), and a theft-deterrent mobile sion to a 455-kHz i-f. Selectivity is ob­ required for full modulation. The mounting bracket. An edgewise meter tained by using a ceramic-filter bypass blanker, on the other hand, interrupts ·movement indicates relative signal at the emitter of the second mixer and the r-f signal path momentarily during strength on receive and relative out­ a ceramic filter at the input of the two­ high-level noise pulses ahead of the put power or SWR on transmit. Also stage 455-kHz i-f section. selectivity circuits. A limiter is a simple included are the usual adjustable Application of dual age voltages to device that operates well enough, but squelch, Delta tune, public-address the r-f stage, plus a single loop to the because of its clipping action can facility, and detachable microphone. second mixer, provides an exception­ cause a-f signal distortion when clip­ The transmitter operates at full legal ally flat output response level. Only a ping takes place. The blanker is more power when the transceiver is con­ 4-dB output change occurred with a sophisticated, operating only for short nected to a nominal 13.8-volt de power 20-dB input signal variation (at 1-10 noise-signal durations. Because it in­ source. The power source can be µV). A 3-dB change occurred with a terrupts the signal path, it is not distor­ either a positive- or a negative-ground 60-dB input change (at 10-10,000 µV), tion producing.) system. Reverse-polarity protection is and a 6-dB change with an input ex­ The push-pull class-B output am­ provided in either case. Stability of cursion of 80 dB (at 10-100,000 µV). plifier is driven by an IC. In our tests, it critical circuits under varying source Approximately 50 µV of input signal delivered a 3.5-watt output at 5.5% dis­ voltages is assured by means of a was needed to register S9 on the tortion at the onset of clipping with a built-in electronic voltage regulator. meter. 1000-Hz test signal. With clipping, the The transceiver measures 8 in. by Other measurements indicated an output was4.5 watts at 10°/o distortion. 63/4 in. by 21/2 in. (20.3 x 17.1 x 6.4 cm) 80-dB rejection of the primary image A · thermistor-compensated squelch

JANUARY 1975 81 was adjustable for thresholds of from synthesizer mixer for the transmitter. creased the adjacent-channel splatter 0.25 to 300 µV. The r-f power output amplifier em­ to -40 dB. With speech at normal mod­ ploys a triple-tuned output-matching ulating levels, the splatter was some­ Frequency Synthesizer. The section. Collector-modulation of the what less. Setting the gain control to crystal frequency synthesizer in the driver stage and power amplifier is the point where the modulation starts Diamond 40 employs six crystals in the accomplished with the receiver's a-f to make the transmitter-on lamp blink 16.965- to 17.215-MHz range. Four of setup plus a speech amplifier for the slightly will usually hold the modula­ the crystals are cut for the 9.545- to mike. (The latter is automatically tion within acceptably safe limits. 9.585-MHz range for the receiver and switched in for this mode.) The fail-safe setup in the transmitter four are cut for the 10.0- to 10.04-MHz With operation from a 13.8-volt functions as follows: If the antenna range for the transmitter. During source the r-f carrier output measured line is badly mismatched to the trans­ transmit, the frequency tolerance held 4.5 watts. The distortion measured 9% mitter, the resulting SWR will produce to within 440 Hz on any channel. at 100% modulation at 1000 Hz, and a large reflected voltage from the SWR The Delta-tune circuit for the re­ the frequency response was 270 to bridge. This voltage is then used to ceiver is detented at its center posi­ 2700 Hz at the 6-dB points. Adjacent­ disable the transmitter drive and thus tion, allowing the CB'er to " feel " when channel splatter, using a 2500-Hz protect the output transistor from it is set to the middle of the channel. standard EIA test tone, was -50 dB. damage under improper load condi­ Advancing the mike gain control for tions. This is a protective scheme we The Transmitter. A triple-tuned an additional 6-dB input-signal level (a would like to see more of in transmit­ bandpass-coupling network mini­ practice the operating manual advises ters. mizes spurious responses from the against) caused clipping and in­ CIRCLE NO. 68 ON READER SERVICE CARD

sary lead wire. Calling it a kit is really a EDMUND SCIENTIFIC KIRLIAN ELECTROPHOTOGRAPHY KIT misnomer, as one does not truly Experimental photography prm'ides fascinating results. " build " it. For example, the variable voltage step-down transformer and the high-frequency induction coil are fully assembled. What one does is set up the system from assembled com­ ponents. 1· The high-quality step-down trans­ .I former, which is plugged into a 117-V ac source, provides output voltages that can be varied from three to eight volts. It includes an on-off switch. The I high-frequency induction coil, which is fed the step-down transformer's low ac voltage, converts the voltage to a high-frequency, high-voltage output. High frequencies are developed by a set of vibrating contacts that interrupt the input at a rapid rate. Though out­ Electrophotography kit is set up on put voltage from the induction coil is top of carton in which it is received. very high, the secondary's output cur­ rent is quite low, being limited by core HOTOGRAPHY with electricity and degrees of brilliance. Some ob­ saturation. Nonetheless, great care P goes back to the 19th century. servers describe it as a pulsing energy should be taken when operating the But it wasn't until Czechoslovakian source. Scientific interest revolves device to avoid a shock. researchers in 1939 published " elec­ around interpreting the corona or Setting up the " Kirlian " kit is simple trophotographs" of leaves displaying " bio-energy" force, which displays enough. Assuming a suitable dark­ strong corona patterns that some in­ changes as a resu It of anger, illness, or ened room for photographic develop­ terest in the field emerged. It was the fear in a human; lack of water in a ing purposes, here are the assembly Russian scientists, the Kirlians, how­ plant; etc. steps: The cardboard shipping con­ ever, who truly developed the method The Edmund Scientific Company's tainer is used as a support for setting in depth over the years, creating a " Kirlian " Electrophotography Kit (No. up, folding one side's flaps inside and wide range of patented apparatus for 71 ,938) at $49.95 uses the principle poking a pencil-size hole in the closed use in various fields. described, opening up a new world of bottom to pass the high-voltage lead. Kirlian photography permits one to photography for experimenters. Placing the high-voltage induction view brilliant emanations from or­ coi I inside the carton, the high-voltage ganic or inorganic objects, made visi­ What It Is. Edmund 's " Kirl ian " lead is pulled through the hole so that ble photographically only when the photography kit consists of a variable it protrudes from the carton. Now the subject is placed in a field of high­ low-voltage transformer ; a high­ carton is resting on its open side, the frequency electrical currents. Using voltage, high-frequency induction closed top acting as a platform with color film, the images are spectacular, coil ; metal electrode; glass plate ; the electrode lead protruding. revealing all colors, shades, patterns photo changing bag ; and all neces­ The twin power leads of the induc- 82 POPULAR ELECTRONICS ti on coil are brought out from the bot­ won't cause eye irritation; do not op­ tom edge of the carton and plugged erate in the presence of anyone with into the jacks of the variable low­ implanted devices such as heart pac­ ~jm voltage step-down transformer that is ers or around children or anyone not positioned outside the carton. Strip­ familiar with normal electrical safety ping about one inch of insulation from precautions.) the high-voltage lead protruding from Either 35-mm film or Polaroid 4 x 5 the carton top, the lead is bent 90 de- sheet film type 58, may be used. The ~ film is placed directly on the glass dielectric plate, centering it over the metal electrode under the glass. The emulsion side is placed face up. An ~ object to be photographed " Kirlian " style is placed directly on the film. For 346Vlays small objects, such as a coin, one's finger is placed on the object to pro­ vide a ground. To Save On Comments. Setting up the Edmund Kirlian Photography Kit was an easy Instruments, job. But in our haste we did not follow Kirlian photograph of a directions to tape down the glass Burglar Alarms, begonia leaf showing the dielectric. After using the system a corona around the edge. while, the glass moved, which allowed an associate to be jolted by a dis­ Automotive & charge. With the glass covering the grees, with the excess wire pushed metal electrode, however, only a mild back into the carton. The square, tingling sensation was felt. Following Hobby metal electrode is then placed on top this, we taped down the hot lead and of the HV electrode lead and the wiped the glass on both sides to be ElectronicsI perimeter of the metal is taped to the sure that moisture and dirt would no! carton with masking tape. Next, the provide an electrical path. The more you know about glass dielectric plate is centered atop We used black-and-white sheet film electronics, the more you'll the electrode and taped down. (ASA 32) , taping it to the glass. How­ If a suitable darkroom is not availa­ ever, 35-mm film, black-and-white or appreciate EIGO. We have awide ble, the photo changing bag should be color, can be used . For the latter, the range of products for you to used. Here, a hole is poked through cassette should be taped close to the choose from, each designed to the bottom to accommodate the edge of the glass, securing the leader provide you with the most high-voltage lead. The lead plus com­ to a bulk-film reloading 35 mm cas­ pleasure and quality performance ponents on top are placed inside the sette, which is taped to the opposite bag , with the bag and its contents rest­ end of the glass. Using a 3/8" wood for your money. The fact that ing on the carton. dowel as a handle, tapering the end to more than 3million EIGO products Completing setup, the following fit the bulk-film cassette, five clock­ are in use attests to their quality tests should be made before photo­ wise turns of the spool (done in the and performance. graphing an object. The stepdown dark) will withdraw sufficient unex­ transformer control should be set to posed film. its maximum, eight volts. Powering A user must experiment with expo­ "Build-it-Yourself" and save the device, you should hear " buzzing" sure. Recommendations by the man­ up to 50°/o with our famous of the interrupter contacts of the ufacturer are a fair guide, but best ex­ high-frequency coil. Next, the user's posure varies due to humidity, film electronic kits. hand should be placed on the glass dampness, object density, etc. Typical For latest EICO Catalog on Test dielectric plate. The result should be a exposures will be 12 to 15 seconds slight tingling sensation due to when the voltage control is set at Instruments, Automotive and Hobby capacitive coupling of the high­ eight. We started at six volts, feeling Electronics, Eicocraft Project kits, frequency current. In the dark, a that there's more control over expo­ Burglar-Fire Alarm Systems and name corona discharge should be seen from sure if time is a bit longer. of nearest EICO Distributor, check reader your hand; maybe, a crackling sound There's no doubt that " Kirlian " service card or send 50¢ for fast first heard . (Caution: Do not operate photography is fun. You 'll be amazed class mail service. equipment if the glass dielectric plate at the results, especially with color EIC0-283 Malta Street, is damaged ; limit skin area exposures film. Edmund Scientific also has a Brooklyn, N.Y. 11207 to about one minute per day; use in a $9.95 starter kit and a more expensive Leadership in creative electronics well ventilated area to prevent ozone " professional" kit. The former uses a since 1945. buildup; use a pair of glass-lensed piezoelectric demonstrator. sunglasses when viewing the corona so that shortwave ultraviolet rays CIRCLE NO. 69 ON READER SERVICE CARD CIRCLE NO. 14 ON READER SERVICE CARD JANUARY 1975 83 From Cleveland Institute of Electronics learn by doing! Perform more than 200 exciting experiments with CIE's fascinating ELECTRONICS LABORATORY PROGRAM!

84 POPULAR ELECTRONICS You get your own 161-piece electronics laboratory... with authentic electronic components used by industry!

You learn how to construct circuits and Testing and troubleshooting are an im­ Modern space-age components like this connect them with a soldering iron, which portant part of your learning experience. IC (integrated circuit) are professional . is part of your CIE laboratory equipment. Included in your laboratory is a precision quality and can be used again and again This "hands on" experience is extremely " multimeter" to diagnose electrical and in many of your projects. Lesson by lesson, valuable in applying what you learn. electronic troubles quickly and accurately. piece by piece your knowledge grows! Prepare now for a high income career in Electronics ... the Science of the Seventies. Electronic miracles are changing you complete our Laboratory Course, facturing, Inc., Scottsbluff, Nebraska, today's world with breathtaking which provides FCC License prep­ moved from TV repairman to lab speed. aration, you'll be able to pass your technician to radio station chief And with t.his growth in electronics FCC exam or be entitled to a full engineer to manufacturer of elec­ technology has come a brand new refund of all tuition paid. This war­ tronic equipment with annual sales need ... a demand for thousands of ranty is valid during the completion of more than $500,000. Ed Dulaney electronics technicians, trained in time allowed for your course. says, "While studying with CIE, I theory and practice to build the You get your FCC License - or learned the electronics theories that products, operate them and service your money back! made my present business possible." them during the Seventies. Marvin Hutchens, Woodbridge , Don't just wait for something to You'll have high paying Virginia, says: "I was surprised at the "happen" in your present job. Get job opportunities relevancy of the CIE course to actual ready now for a career you'll really Electronics is still young and growing. working conditions. I'm now ser­ enjoy with a good income and plenty In nearly every one of the new excit­ vicing two-way radio systems in the of opportunity for advancement. ing fields of the Seventies you find Greater Washington area. My earn­ electronics skills and knowledge are ings have increased $3,000. I bought Experience with experiments in demand. Computers and data pro­ a new home for my family and I feel is your best teacher cessing. Air traffic control. Medical more financially secure than ever "Hands on" experience helps to re­ technology. Pollution control. Broad­ before." inforce basic theory. When you casting and communications. With a learn by doing, you discover the CIE Diploma and an FCC License Send now for 2 FREE BOOKS "how" as well as the " why." You'll you can choose the career field you Mail the reply card or coupon for our find out for yourself the right way as want .. . work for a big corporation, a school catalog plus a special book well as the wrong way to use elec­ small company or even go into busi­ on how to get your FCC License. For tronic components. How to construct ness for yourself. your convenience, we will try to have your own circuits, to discover trouble Here's how two outstanding CIE a representative call. If coupon is spots and learn how to fix them. And students carved out new careers: missing, write: Cleveland Institute of with CIE's special Auto-Programmed® After his CIE training, Edward J. Electronics, Inc., 1776 E. 17th St., Lessons, you learn faster and easier Dulaney, President of D & A Manu- Cleveland, Ohio 44114. Do it now! than you'd believe possible. CIE's fascinating course, Elec­ @ tronics Technology with Laboratory, Cleveland Institute of Electronics, Inc. teaches you Electronics by making C I E 1776 East 17th Street, Cleveland, Ohio 44114 it work before your eyes. And you do Approved Accredited Member National Home Study Council it yourself, with your own hands. under Please send me your two FREE books: G.I. Bill 1. Your illustrated school catalog, "Succeed in Electronics. " Importance of FCC License 2. Your book, "How to Get a Commercial FCC License ."

~nd our Money-Back Warranty All CIE career I am especially interested in : O Electronics Technology with Laboratory Many important jobs require an FCC courses are ap· O Electronics Technology O Industrial Electronics License and you must pass a Gov­ proved for educa­ D Electronic Communications O First Class FCC License O Broadcast Engineering o Electronics Engineering ernment licensing exam to get one. ti ona I benefits Name ______Age ___ But, a recent survey of 787 CIE under the G. I. Bill. If you are aVeteran ( PLEASE PRINT ) graduates reveals that better than 9 or in service now, Address ______out of 10 CIE grads passed the FCC check box for G. I. License exam. Bill information. City ______State _____..ip___ That's why we can offer this fa­ D Veterans and Servicemen: Check here for G.I. Bill information-. PE-72 mous Money-Back Warranty: when ..______, ------­ CIRCLE NO. 9 ON READER SERVICE CARD JANUARY 1975 87 Solid State

By Lou Garner

LOOKING INTO THE CRYSTAL BALL

F YOU 'VE been a regular reader of this column, you SGS-ATES L 120 and L121 (SGS-ATES Semi-conductor I know that I enjoy playing an annual guessing game with Corp .. 435 Newtonville Ave.. Newtonville, MA 02160). Both the electronics industry, predicting what new semiconduc­ devices are offered in 16-pin DI P's, both are priced at $6.00 tor products or technological advances will be introduced each in unit quantities, and both are intended for control each year. For nearly two decades, my predictions have functions in industrial and consumer applications. The proven accurate better than 90% of the time. Because of L 120 is a Triac/SCR phase control and the L 121 a this record , some have accused me of being an inspired Triac/SCR burst control. prophet. Not so! • The development of one or more new solid-state Actually, my annual predictions are based on an extrapo­ transducers . WOW! We really hit the jackpot on this one. lation of known developments in the industry. A " guessti­ Several manufacturers introduced new solid-state trans­ mate" of where present trends are leading and what could ducers during 1974, with the National Semiconductor be done with present technology. The method is similar to Corporation now offering so many types that it recently that used by science-fiction authors, but extended to the published the industry's first catalog/handbook on pres­ immediate, rather than the distant future. sure and temperature transducers. Entitled Transducers: Sometimes, my predictions have proven early by a year Pressure and Temperature , the 160-page volume is much or so-simple examples of over-optimism and expecta­ more than a mere listing of device specifications and op­ tions that the industry would move faster in some areas tions. It covers general transduction theory as well as the than in others. Just as often, however, I've goofed in the theory of operation of IC transducers in particular, and opposite direction, predicting a new development which is includes a number of useful tables plus a lengthy glossary announced before the colum appears in print. of transduction-related terms. The book's applications Let's see how I fared with the predictions made in section d iscusses automotive, medical, and audio uses, January, 1974. As you may recall , I predicted: cable fault location, and even musical instruments, such as • A substantial drop in the prices of digital electronic an electronic clarinet that comes on like a Sousaphone. watches from the present hundreds of dollars . Score one Copies of the book are available without charge on let­ for the OM! Surprising just about everyone and catching terhead request to the Marketing Services Department, some manufacturers with their inventories up, National National Semiconductor Corporation, 2900 Semiconduc­ Semiconductor Corporation's Novus Consumer Products tor Drive, Santa Clara, CA 95051. Division (1177 Kern Avenue, Sunnyvale, CA 94086) intro­ • The introduction of low-cost (about $100) prepro­ duced a line of si x digital electronic watches in early fall grammed business calculators. Another winner! Virtually with a list price on one model of only $125.00 all major calculator manufacturers have introduced i[lex­ • Comparable reductions in the prices of digital electronic pensive special purpose models. Casio, Inc. (Consumer clocks. Score another! At the same time that Novus an­ Products Div.. One World Trade Center, New York, N.Y. nounced its new low-priced electronic watches, it also 10048), for example, offers one model, the Mini Root, announced a line of three digital electronic alarm clocks. which can supply square roots at the touch of a button and The lowest priced model in the line lists at $34.95! which provides automatic percentages for figuring mark­ • LED's atprices comparable to those of miniature incan­ ups and discounts, at a list price of only $54.95. The Cole­ descent lamps in small quantities. Another home run Parmer Instrument Co. (7425 North Oak Park Ave., (bull's-eye, or whatever)! Recent advertisements in these Chicago, IL 60648) offers a metric conversion computer pages offered type MV50's at six for a dollar, MV5024 with full 5-function capability at a list price of only $84.50. equivalents at eight for a dollar, MV5222 equivalent green And these are but a small sampling of the models intro­ LED 's at five for a buck, and Mini-Red LED 's similar to the duced during 1974! MV50 at a whopping ten for a dollar. • Digital electronic test instruments, such as VOM's and • The introduction of control-function /C 's as stock items. frequency meters, at prices comparable to those of in­ Chalk up another score! Space limitations prevent our struments using moving-coil meter movements. Is there listing all of the various control I C's now available through any doubt? major distributors, but two moderately priced types which • Development of a new semiconductor manufacturing should be of interest to serious experimenters are the technique or a refinement in current techniques which will 88 POPULAR ELECTRONICS improve quality, increase yield rates, and lower costs. I admit to "hedging" slightly on this prediction, offering two alternatives. However, fortunately for the OM , both options were fulfilled during 1974. Nearly every major semiconduc­ tor manufacturer was able to improve production tech­ niques to the point of boosting product quality while, atthe same time, lowering prices. In addition, several firms in­ THE LARGEST troduced new techniques. RCA, for example, introduced a COLLECTION EVER technological advance for the semiconductor industry by Over 3,600 circuit diagrams, complete combining MOS and bipolar devices-PMOS, bipolar and with component values, in one handy COS/MOS-on a sing le chip. The first device offered based volume, all clearly indexed and cross­ on the new technology is the CA3130 operational amplifier. referenced for speedy answers to your immediate design needs. Supplied in an 8-lead T0-5 package, the CA3130features a gate-protected p-channel MOSFET input stage with an extremely high input impedance of 1.5 x 1012 ohms and a complementary-symmetry (COS/MOS) output stage capa­ ble of swinging the output signal voltage to within a mere 10 mV of either supply voltage terminal. In addition, the device offers a wide 15-MHz bandwidth and has a sink and source current capability of 20 mA. Short-circuit pro­ tected, the CA3130 has a broad range of applications, including ground-referenced single-supply and fast sample-hold amplifiers, long duration timers and mono­ Whatever your project-'a hi-fi system, a burglar alarm, stables, high-input-impedance comparators and wide­ a solid state metal detector, an automatic timer-you name it, you'll find the circuit that best meets your band amplifiers, voltage-followers and regulators, peak needs in this, the largest single-volume collection of detectors, single-supply full-wave precision rectifiers, and illustrated circuits ever to be published. photo-diode sensor amplifiers. 131 CHAPTERS, each devoted to a particular type of • The announcement of an unusual new solid-state circuit, present 3,600 individual circuits, all with essential construction and adjustment details, design precautions device. Another score! Not one, but several unusual new and other practical data. The advantages and disadvan­ devices were introduced during 1974, many of which were tages of the various circuits are also given so you can discussed in t'hese pages (including the CA3130). In mak­ decide quickly and easily what best meets your needs at the moment. ing the original prediction, I suggested that one possibility FAST, EASY USE. The Index has over 10,000 entries was a special type of LED, speculating that it might have that list-and cross-reference-circuits by all their differ­ bilateral switch characteristics. In fact, a family of unusual ent names, by performance parameters, by applications, and by a host of other relevant categories. Perfect for new LED's was introduced by Litronix, Inc. (19000 Home­ super-fast looking or leisurely leafing. stead Road, Vallee Park, Cupertino, CA 95014)-the RCL-200 series. These devices do not have switching ' ~~~Pi.e 9'.<>N.T~tiTS 9'.ladrapnonJ'.6 ~ i rc~its, ; :. ~; : !,ai:f~': characteristics as we speculated, but do incorporate a recorder circuits ... c1t1zens band c1rc;uits ·. .1 .· • ·rnei:i,'r; ·surjng circuits .. .. filter circuits .•. atnpli itcuitffe~: built-in bipolar current-regulator IC, permitting their use . .• code .circuits ... te_!ephone circurt ., sign.al!, on de supply voltages of from 4.5 to 12.5 volts without an ' generator 9ircu[ts ... flasher c;;ircuits ~Witching external current limiting resistor. cirquits ., . . anqthousaflds more!

trofitting, but will be offered later as an optional accessory ADDRESS------~------by one or more major manufacturers. CITY------STATE ____ZIP ___ • A low-cost electronic calculator designed specifically This offer good only in the U.S. and Canada. 23-A651-4003·3 for the children's market. As I visualize this product, it will L------~CIRCLE NO. 22 ON READER SERVICE CARD JANUARY 1975 89 be a basic 4-function calculator, but will be sold with a Rx rWNM-, booklet slanted to teach a child not only to use the cal­ I I BP2 culator, but to relate to standard mathematical tech niqu.es . r It may also include several " game" features. The selling price probably will be well under $20.00, based on present values. • An increasing variety of multipurpose consumer and + :.r-~r--., office electronic products. Typically, a combination alarm RI I eK clock/calendar/calculator or a combination intercom/ dic­ tating machine. ~I • The development of low-cost portable electronic games. I --~~~~~~--o--~ These would be based on calculator technology, but would + 18V be self-contained and , unlike Magnavox's Odyssey, would POWER SUPPLY CT not require a TV set. 18V R2 • The development ofa high-output orhigh-intensity LED. -o 2e0Jt A standard LED can be pulsed at currents many times higher than its average continuous rating (typically, 1 A for a 50 mA LED) . If designed specifically for pulse applica­ tions, it may be possible to use a LED as a light source for L i near scale ohmmeter uses two special purpose photography (such as infrared mic­ intergrated circnits. When the circuit is rophotography), or even as a warning light. properly balanced (via range switch and • The development although not necessarily the commer­ potentiometers), the meter rea.chng is cial production, of solid-state energy control centers for pmportio11cil to the 1111.known resistor. homes and offices. With the increasing energy crisis, over­ all heating/cooling efficiency becomes more and more im­ course, depending on whether a DIP, TO, or minidip type portant. There are many ways in which solid-state circuitry device is used. Range selector S1 is a single-pole, four­ and devices could be used to increase the efficiency of position rotary switch, R1 a conventional linear poten­ building heating/cooling systems. Typically, controls to tiometer, and R2, R3, R4 and RS are small trimmer pots, monitor temperature and humidity, adjusting energy flow although full-sized controls may be used. A dual 18-volt to maintain the proper levels without waste, controls to regulated (or zener stabilized) de power supply is required adjust blower speed to an optimum level for heating or for operation, while the readout instrument should be a cooling, and warning systems to alert the user to system high-impedance VTVM or FET VM. inefficiencies (such as clogged filters). In his letter, Guenther writes that he assembled his That does it! Next January, we 'll check our score. model as part of a home-built FET voltmeter, providing a pushbutton switch between IC2 ' s output and the Readers Circuit. If you 've used an ohmmeter to any voltmeter's input to prevent an off-scale reading when the extent, you 've probably been frustrated on several occa­ test terminals are open. sions when trying to interpolate a value at the " squeezed " Except for establishing the readout voltmeter range, the end of the nonlinear scale found on most such instru­ reference voltage adjustment, R1 , is completely noncriti­ ments. A little frustration apparently was too much for cal , according to Guenther. He suggests calibrating the reader M. J. Guenther (1169 Prairie Rd ., Por.t Coquitlam, instrument by using mid-scale value precision (1% or bet­ B.C., Canada), for he put on his thinking c_ap and devised a ter) resistors as test units to adjust each range potentiome­ linear scale ohmmeter, which he proceeded to build and ter. In his model , Guenther used test resistors (as Rx) of 50, has been using for some time. His circuit is illustrated 500, 5,000, and 50,000 ohms, adjusting R2, R3, R4, and RS, above. respectively, to provide ranges of 0-100, 0-1 ,000, 0-10,000 Guenther's design features a pair of op amps, IC1 and and 0-100,000 ohms. IC2, a reference voltage source, established by R1 , various ranges, selected by S1, and a voltmeter readout. Test ter­ Device/ Product News. If my discussion of field-effect minals BP1 and BP2 are provided for checking unknown transistors and their applications in last November's col­ resistance (Rx) values. umn stimulated your interest in these versatile devices, you The reference voltage obtained from R1 , stabilized by may want to investigate recent offerings by Siliconix, Inc. voltage follower IC1, is applied to IC2's non-inverting (2201 Laurelwood Road , Santa Clara, CA 95054) : these input. At the same time, IC2's output is coupled back to its include a pair of vhf/uhf FET's and a new series of inverting input through a voltage divider consisting of the monolithic matched dual FET's. unknown resistor, Rx, and a preselected range resistor, R2 The new vhf/uhf devices are basically the popular U310 thru R5. The net resu It is that IC2's output voltage is equal n-channel high-frequency JFET supplied in epoxy T0-92 to the reference voltage plus the reference voltage times or ceramic OD-81 package configurations. These devices the ratio of the unknown and range resistors. When a may be used as amplifiers, oscillators or mixers. voltmeter is used to check the potential difference be­ Siliconix's new dual JFET's, designated the E410 family, tween IC2's noninverting input and its output, the initial are epoxy-packaged n-channel devices intended for low­ reference voltage is cancelled , giving a reading which is and medium-frequency small-signal differential amplifiers directly proportional to the unknown resistor's value, the requiring matched gate-source voltage, high common­ basic requirement for a linear scale. mode rejection ratio and low output conductance. The Guenther used type 741C op amps in his model, but three units, types E410, E411 and E412, have a maximum suggests that a single type 747 dual op amp or other 741 G-G voltage of ±40 V, a maximum G-D or G-S rating of - 40 types may serve as well. The pin connections will vary, of V, and a maximum gate current of 50 mA, with a total 90 POPULAR ELECTRONICS package dissipation of 350 mW. Their common-mode re­ jection ratio is at least 70 dB. In addition to its new FET's, Siliconix also has an­ nounced a new line of low-capacitance, high-impedance diodes intended for circuits requiring clipping, clamping , New or over-voltage protection. Identified as the PAD family (pico-ampere diode), the new devices feature minute leak­ The 1975 age currents ranging from 1 pA (PAD-1) to 100 pA Engineering (PAD-100) and extremely low interelectrode capacitances of 0.8 to 2.0 pf. The typical forward voltage drop for all Manual & units is 0.8 volts, the maximum forward current is 50 mA, and the total device dissipation 300 mW. Purchasing A new series of low-voltage varistors has been intro­ Guide! duced by GE 's Semiconductor Products Department A 11 must 11 for (Bldg. 7, MD #49, Electronics Park, Syracuse, NY 13201). Performing somewhat like back-to-back zener diodes, hobbyists, experimenters, these devices are ideal for protecting costly power transis­ repairmen and technicians! tors against transient voltage peaks when used in high­ ... Thousands of hard-to-get electronic .rx.r: current inductive circuits, such as power supplies, inver­ parts and supplies. Order now! ·~- ters, converters, alarms, solenoid drivers, and audio am­ ~, ­------plifiers. Physically similar to disc ceramic capacitors, the .Send $1 to Allied Electronics new devices, designated the " ZA" series, are offered with Dept. PE75, 401 East 8th St. ratings from 26 Volts de, 20 Volts rms to 81 Volts de, 60 Fort Worth, Texas 76102 Volts rms. Motorola's Semiconductor Products Division (P .O. Box 20924, Phoenix, AZ 85036) has announced five new rug­ gedized r-f power transistors which should be of interest to hams and other communications buffs. Designed for 40-to-110-MHz mid-band international mobile radio appli­ cations, the new devices, types MRF 230 through MRF 234, are drivers and final amplifiers rated at 1.5, 3.5, 7.5, 15 and . 25 watts output, respectively. Individual device gains are kept within 10 dB, while operation at VSWR 's of up to 30 :1, at any phase angle, can be tolerated. Unit prices range from $2.30 for the MRF 230 to $16.90 for the MRF 234. Back East, RCA's Solid State Division (Box 3200, Somer­ ville, NJ 08876) has introduced three new families of medium-power transistors and eight new general-purpose IC op amps. The RCA29/SDH , RCA31 /SDH and RCA41 /SDH series are single-diffused hometaxial-base versions of the RCA29, RCA31, and RCA41 epitaxial base series, respectively, and are intended for a wide variety of switching and amplifier applications, such as series and shunt regulators and driv­ ers and output stages of high-fidelity amplifiers. All the devices are supplied in JEDEC T0-22AB packages. The RCA29/SDH series has typical turn-on and turn-off Send for FREE Tiger booklet (20 times of 2.3 µsand 6 µs, respectively, with a minimum beta pages) which answers all your of 15, measured at 1 ampere. VCEo ratings range from 40 to questions. 100 volts, depending on type. Featuring similar turn-on and turn-off times, but a minimum beta of 10, measured at 3 amperes, the RCA31 /SDH series is offered with compar­ able V cEo ratings. Finally: the RCA41 /SDH series has typical Name·------~------~ turn-on and turn-.off times of 3.2 µsand 3.7 µs, a minimum beta of 15 at 3 amperes, and voltage ratings of 40 , 60, and Address------~ 80 volts, depending on type. Designated types CA107T, CA207T, CA307T, CA101T, City CA101AT, CA201T, CA201AT and CA301AT, RCA's new IC op amps are direct replacements for standard industry State______Zfp.______types such as the 107, 207, 307, 101, 101A, 201 , 201A and 301A in packages with similar terminal arrangements. CLIP OUT THIS AD AND SEND TO­ These are dual-supply, high-input-impedance devices suitable for use in sample and hold, comparator, low­ TRI-STAR CORP. frequency waveform generator, long-interval timer, sum­ ming amplifier, and multivibrator applications. All eight P. 0. Box 1727 Dept. E types are furnished in 8-lead T0-5 style cases. · ~ Grand Junction, Colo. 81501 CIRCLE NO. 35 ON READER SERVICE CARD JANUARY 1975 91 easy if I were a 5-channel tape recor­ der, but Morgan has been doing it for 8 years and easily sorts out the audio bedlam. As the 100 horses of the Cessna engine struggled to lift us into the air, I regretted the box of Oreos I CB Scene had eaten the night before. " Hey, here comes Eddie Ricken­ backer!" It was the first CB voice of the flight. Morgan wheeled the plane around and headed toward a row of By Len Buckwalter, K10DH · boats moored below, then lowered CB'S RED BARON the plane's right wingtip to point out a single cabin cruiser. "That's the city HERE we were at 1,000 feet, a Volkswagen car radio!). Back in the police," he explained. " They monitor T our wings at a crazy angle, the minuscule baggage compartment is a channel 13. " Morgan exchanged ground rushing up, when all of a typewriter-size vhf radio and the rest pleasantries with the floating police sudden .... of the cabin is criss-crossed with the and I was suddenly impressed at the That's how it felt when I recently microphone cords and dangling good fortune of CB-equipped boat­ took a ride with one of the world 's headphones. With all this electronics men in the area. Maybe the U.S. Coast rarest birds-a flying CB reporter. His aboard, no wonder Morgan was con­ Guard won't hear CB distress calls, name is Morgan Kaolian, and he pilots cerned about poundage. but there's a good chance they'll be a flivver of a plane on weekends for a The CB installation turned out to be intercepted by this channel 13 local radio station located near the big something less than you 'd find search-and-rescue team. boating areas of New York and Con­ aboard a Boeing and more like a typi­ On an average weekend Morgan necticut. Morgan's become something cal hobbyist's shack-a disarray saves about two boats in distress. It's of a legend in these parts because he that's understood only by the person most efficient if the boat has a CB rig buzzes through the air for 18 hours who grew it. Since the Cessna's Lil­ because its captain simply calls on every weekend to deliver half-hourly liputian cabin was already bursting channel 13 and may speak directly to broadcasts of weather, fishing, sea with instruments, the CB set was the aerial angel-of-mercy himself. The conditions and road traffic, plus a few stuffed into a map pocket behind range of a CB "air m.obile" is very surprises. When I caught wind that the backrest of a seat. The tiny great with its lofty antenna, and talk­ Morgan depends heavily on CB, I de­ knobs of the CB rig peeked out of ing distances of 50 miles are average cided to investigate, and maybe the pouch like a baby kangaroo. The (or double that when altitudes rise to wangle a free hop in his flying antenna installation, though, was an three or four thousand feet) . If a boat machine. aircraft-type spike loaded for CB has no CB , Morgan may flit to a Most people think flying reporters channel 13 and permanently mounted nearby boat and direct it to the crip­ are in helicopters. Not. so in this case. on the fuselage. Power for the rig was pled craft. When radio communica­ The plane is aviation 's Model A; a picked up through the aircraft's tions won 't work he relies on more two-place Cessna-150 that cruises 12-volt de buss in automobile fashion. sensational feats. He'll drop written about 90 mph, squeezes 15 miles As we taxied out for take-off, the instructions in a sandwich bag or fly from a gallon of gas and emits about pilot clamped on headphones and down low and shout directions. as many decibels as an overweight handed me a pair. The "cans" were a " Won 't the noise drown out your wasp. A helicopter, on the other hand, comfortable set-until Morgan turned voice? " I asked, with some doubt. noisily chomps the air, costs upwards up the audio with a wicked smile. All " No, I kill the engine gliding down." of $80 an hour to operate and is usu­ the plane's radios feed into the Morgan's uncanny skill at skim­ ally an expensive big-city bird . phones simultaneously. Trying to ming the waves reaps another Morgan's mini-machine slashes the catch the voices of the control tower, bonanza for CB'ers in the area. It's cost, and CB takes a share of the ground controller, CB receiver, vhf fish-spotting by air. To demonstrate, credit in the electronic department. receiver and AM monitor would be he lowered the Cessna's nose and When I first spoke to Morgan on the phone he asked me how much I weighed. " One hundred ninety," I re­ pli.ed , wondering if the beefy figure Flying reporter would ground me. The reason he Morgan Kaolian uses asked is that the plane is loaded to CB for much of his the gunnels with radio equipment and aerial communications. sprouts antennas like a flying por­ cupine. A two-way vhf link on 161 .7 MHz carries his voice to the ground for retransmission over WICC, an AM station on 600 kHz. In the instrument panel there's an AM receiver so he can monitor the radio announcer for cues (but a closer look reveals it to be 92 asked me, " Do you have any aversion to low flying?" As the sea rapidly filled the windshield, I replied, " N­ n-n-no." Blue fish, he explained, are visible as they break the surface, while bunkers expose themselves by thrashing about. Sc.hools of fish below the surface look like dark holes. If he spots any giveaway signs, he'll report them to CB'ers below who call in. He's even been known to as­ sist unlucky anglers with a helpful " Follow me." The plane was now over land and flying parallel to a busy interstate thruway. Although he gives traffic re­ Antenna, on plane's fuselage, ports on his regular AM broadcasts, I is cut for channel 13. wanted to see the interaction be­ tween a CB-equipped plane and an the church is on Brooklawn Road? automobile in motion. We raised a Some fellow is on his way to a wed­ mobile who described himself as a ding and he's lost. " yellow Chevy pickup truck with a load " Where are you?" asked Morgan. When the driver gave his location, Morgan swooped down like a hawk on a hapless hare. " Is that you in the red Corvette?" 'That's me." " Well just keep going, the church is straight ahead ." Chalk up another save for CB. Morgan even saw the man going to the wedding! The airport runway lights were al­ ready glowing as our Cessna touched down at the end of the day. Moments before we had listened on channel 10, with its CB-equipped truckers talking of roads and loads, or inviting each other to coffee at the next stop. I was surprised by one trucker who asked CB set is carried in another driver if he had a " reefer." pocket behind seat. Morgan quickly explained that he meant a "refrigerated " truck. (He of lumber travelling on Route 1. Sec­ seems to know a little about every­ onds later, over a tangle of roads thing, which may explain why he's choked with homeward-bound vehi­ also called the " Flying Mouth." ) A cles, Morgan started circling. " Do you twist of the selector to CB channel 9 Catalog see it?", he asked me. All I could see brought remarkable silence, consid­ VALUE PACKED WITH was traffic-but it seemed he spotted ering that it's often misused and our THOUSANDS OF everything below about an hour be­ receiving range in the air was so ELECTRONIC BARGAINS fore I did. great. " I see you! " peek-a-booed the yel­ Morgan and his aerial antics via CB low Chevy. Finally, looking like a may serve as an inspiration for other Tonka Toy, the teeny mobile with its pilots and communities. He's spread­ matchstick load of lumber caught my ing tremendous goodwi II for CB and eye . Morgan nudged me and , with a proving the medium's worth in public gleam in his eagle eye, said ; "I esti­ service. The only precaution is that mate he's going 30 miles per hour." this sort of activity should be done Olson Electronics Dept. 13 He squeezed the CB mike and fired only by experienced airmen. Morgan 260 S. Forge St. , Akron, Ohio 44327 I the question. has a good luck charm (an "evil eye" ) I Name I "I'm going 30 miles per hour" an­ pinned to the roof of his cabin, but his I swered the yellow pickup. 8 years of accident-free reporting is Street I Morgan's ability to interface with also helped by 4,000 hours in the air City ______I road traffic has even rescued lost and his experience as a military flier. State ______Zip _____ I souls on the ground. One time on CB Thanks to him we can say CB is on I he heard; ·:Does anyone know where land, at sea-and in the air, too! ~ \t~t~~------jCIRCLE NO. 26 ON READER SERVICE CARD JANUARY 1975 93 Other waves leave the antenna at var­ ious angles from the tangent. Let us look at two of the signals. The wave with the higher departure angle, also Amateur called the wave angle or angle of radiation, first enters the D layer, where it is attenuated to a degree in­ Radio versely proportional to its frequency. This is due to the fact that each time the signal collides with an electron or By Herbert S. Brier, W9EGQ ion, part of its energy is lost in excit­ ing the particle. Since the D layer is so RECEPTION AND THE ATMOSPHERE dense, much attenuation takes place here. D-layer absorption is so great at AVE you ever turned your solar energy, the D layer disappears low frequencies (5 MHz and below) H receiver on and tuned across a after sunset. The E layer, which like that most of the signal doesn't make it band only to find that it was com­ the D reaches its maximum ionization through this layer. This is why 160 pletely dead? This has probably hap­ level at noon, is at a minimum around and 80 meters are usually " dead " dur­ pened to every amateur at one time or midnight, when the free electrons re­ ing the daytime, but can open up at another. The first reaction is, " Oh , no! combine with the ions in the absence night. · Something's gone wrong with my re­ of solar radiation. The F, and F2 layers If the signal is strong enough , ceiver!" In most cases, though, the merge into a single F layer after sun­ and/or of high enough frequency, it fault lies not in the gear but in the set, at a distance between those of the will pass through the D layer with a propagation conditions affecting the individual layers. Sincethedistribution good degree of strength. It will then band or bands. Why are bands so of atoms at this height is so thin, the travel up to the E layer. If the E ioniza­ fickle and unpredictable? recombination process is much tion is high enough, and the wave The reasons for such occurrences slower than in the D or E layers. Max­ angle is below a critical value, it will lay in the interaction of the atmos­ imum ionization occurs at noon, and be reflected back toward the earth at phere, the sun, and radio waves. Let's tapers off very gradually after that, re­ about the same angle as the incident consider the nature of these relation­ maining at a fairly high level through one. The wave will then pass through sh ips, and how they affect radio com­ the night. A minimum is reached just the D layer and reach the earth at a munications. before sunrise, at which point the good distance from the transmitter. Our atmosphere consists of four ionization increases rapidly. Within an If the E layer is not highly ionized, distinct regions-the troposphere, the hour or two, it is back to daytime the wave will pass through it and stratosphere, the ionosphere, and the levels. reach one of the Flayers, although its exosphere. Two of these strata di­ The final stratum, called the exo­ direction may be modified by partial rectly contribute to the propagation of sphere, is made up mostly of protons bend ing. When the wave reaches the radio waves. The troposphere, which (hydrogen nuclei), and other charged F layer, it will be reflected back to­ extends from 0 to 7 miles, (0 to 11 .2 particles that have been carried from ward earth if the wave angle is less km) can act as a waveguide for vhf and the sun as part of the " solar wind ." than the critical value, and the fre­ uhf signals, but has little effect on hf This reg ion acts as a primary shield quency is below the " maximum usa­ transmissions, as does the strato­ . against the buffets of solar distur­ ble frequency," or MUF. If the angle sphere, which extends from 7 to 25 bances, but its effect on radio prop­ and/or frequency is greater than miles (11 .2 to 40 km). From 25 to ap­ agation is not great. these values, the wave will pass into proximately 250 miles (40 to 400 km) When the transmitter, at T, causes space. If the wave is sent back, it will we find the ionosphere. In this region, the antenna to radiate, the waves will pass through the other layers, and rarified gas molecules and atoms can leave the antenna at various angles. perhaps be sent back up by the E lose some of their·electrons when ex­ The one that travels straight up enters layer, and reflected down by the F cited by solar radiation. They disas­ through the ionization layers and es­ layer at another point. The greatest sociate into ions and free electrons, capes into space, never to return. range available from a " single hop" having positive and negative charges, respectively. Since the ions are thousands of times more massive than the electrons, they tend to be much less mobile. The electrons, however, tend to cluster in layers-the D layer, at 37-57 miles (60-92 km) , the E layer, at 62-71 miles (110-115 km) , the F1 layer, at 99 miles (160 km) , and the F2 layer, found between 130 and 261 miles (210-420 km), depending on the season, the degree of ionization, and other variables. (See diagram shown at right.) At night, the picture changes Signals may be reflected by a layer of the ionosphere or escape slightly. In the absen.ce of the ionizing into space. R ange is determined by layer height and wave angle. 94 POPULAR ELECTRONICS spots, the ionization level go up. For further information on modern There is an 13leven year sunspot cycle. vhf operation, try the VHF Handbook The last maximum occurred about 5 For Radio Amateurs, by Herbert S. years ago, and we are now well into Brier, W9EGQ, and William I. Orr, the waning period. W6SAI , Radio Publications, Inc., Wil­ As we are well into the waning year ton , Conn., or FM and Repeaters , of the cu rrent sunspot cycle, the 14-, ARRL, Newington, Conn. These 21-, and 28-MHz bands will normally books are available from most be dead after dark for the next few amateur equipment distributorl). months-except for unpredictable In addition, do not hesitate to put "short-skip" propagation conditions out a couple of CO's on an apparently that can occur at any time on these dead band. One of the never-ending bands. In addition, unless you have fascinations of amateur radio is hs better-than-average 3.5- and 7-MHz unpredictability. Also, th·e bands are Rick, WB9EWQ , uses a Heathkit antennas, signals on these frequen­ often open to remote localities; and Electronic Keyer urith HW-16 cies become weak and "hard to work no one ever finds out because of the and HW-101 transceivers. as the evening progresses. If your an­ lack of activity at the right times and tenna system is less than top-notch, places. Evidence of this is furnished off the F layer is about 2500 miles you may hear operators with good in practically every amateur contest. (4000 km), and about 1250 miles 3.5- and 7-MHz antennas having no (2000 km) from E-layer reflection. trouble working stations you can News and Views. Send news, The range available from this iono­ barely copy. Unless you can put up comments and pictures for possible spheric reflection (also called sky­ better low-frequency antennas, the publication in this column to: Am­ wave propagation) depends on the easiest way to cope with the situation ateur Radio, Herbert S. Brier, c/o height of the layer(s), the degree of is to do more daytime operating. Al­ POPULAR ELECTRONICS , One Park Ave., ionization, the angle of radiation and though the 28-MHz band will often be New York, NY 10016. ~ transmitter output power. In the dia­ dead, even in the daytime, the 3.5­ gram are two sky waves received at R1 to-21-MHz bands are and should con­ and R2. The angle of radiation of the tinue to be useful for distances from SELECTED CONTESTS wave reaching R1 is much greater 100 to several thousand miles from than that appearing at R2, and the morning to night for the next few ARRL VHF SS Contest; 2:00 P.M. local time, Saturday, Jan 7, to midnight, local range, as you can see, is much less. years. time, Sunday, Jan. 8, 1975. Exchange: While it is possible to cover the dis­ You will also feel the effects of sea­ number of contest contact; " A" if your tance to R2 by mqre than one hop sonal influences. Since the earth is power input is less than 50 watts, " B" if with a higher angle of radiation, the closer to the sun in winter, F2 ioniza­ it is 50 watts or more; your call letter; multi-hop signal will be weaker. Each tion is more intense and higher MU F's " check" last two digits of year licensed ; time the wave hops, it loses about 6 are the rule. E-l~yer MUF's are gener­ ARRL section. dB or one " S" unit of strength. A ally lower in winter than in summer. International DX Contest (ARAL) ; two-hop signal would thus be 12 dB The F1 layer often disappears entirely 0001 GMT, Feb. 4 to 2359 GMT, Feb. 5, weaker than one which arrives after a during the winter, while it demon­ and same time March 4 and 5; phone. single jump. strates MUF's of about 5 MHz in the Same times, Feb. 17 and 18, and March 17 and 18; CW. Send signal report and Amateurs who wish to work DX are summer. Night-time MU F's during the name of your state or province to each interested in having antennas which winter of the minima may drop to less DX station worked. Receive signal re­ radiate the larger portion of applied than 4 MHz, as you will notice over port and power input. Score: add the power at low angles. It has been the next few months. number of different stations worked on found that the median wave angles If hf conditions deteriorate to the each band and multiply by number of for distant signals arriving at the re­ point where few contacts are possi­ different countries worked. ceiver antenna on the hf bands ble, and you are looking for more Novice Roundup (ARAL) ; 0001 GMT, are-28 MHz, 9 degrees; 21 MHz, QSO 's, investigate the amateur vhf Feb. 4, to 2359 GMT, Feb. 12; operate a 12-14 degrees; 14 MHz, 15 degrees; 7 scene. If your attention has been total of 30 hours. Novices can work · MHz, 30 degrees ; and 3.5 MHz, under focussed on the frequencies below 30 anybody. Others work only novices. Ex­ change call letters, signal reports, and MHz, you cannot imagine the popula­ 45 degrees. For horizontal dipoles, name of ARRL section. Novic.e scoring: the following heights will give the de­ tion explosion that has taken place on add the number of different stations sired radiation patterns: 28, 21 and 14 the amateur frequencies above 50 worked to the highest code speed re­ MHz-70 feet; 7 MHz-70 to 90 feet; MHz-·especially on the 144-148-MHz corded on your ARAL code-proficiency and 3.5 MHz-90 to 140 feet. These band. This is due to the wide avail­ certificate. M!Jltiply by the sum of sec­ heights are not absolute, since there ability of low-power vhf FM transceiv­ tions and countries (other than ARRL are times when a lower or higher ers about the size of a big box of sections) worked. height would be more desirable. candy. When these units are used in Cqmplete literature and last-minute conjunction with the vhf repeaters rule changes for each of these contests are available from ARAL, Newington, CT Solar Influences. Th13 degree of that have sprung up all over the coun­ 06111 , upon request accompanied by try, ultra-reliable local communica­ ionization is dependent on the ac­ an addressed return enve.lope. Affix 8 tivities of the sun, and the proximity tions have become an ·actuality for cents postage for 3rd cl)s:s return, 30 of the earth to the sun. Sunspots are any operator within 25 or 30 miles of a cents for first c;lass . Send seores to directly related to the levels of solar repeater. Antennas need not be same address. radiation. When there are many sun­ elaborate. JANUARY 1975 97 used. To reduce this loading effect, we began using a 10:1 divider to increase· the input impedance. But this, natur­ ally, reduced the signal level available Test Equipment to the scope. We then had to crank the vertical gain way up, and sync some­ times became unstable.The circuit Scene shown at (B) uses a form of bootstrap­ ping to produce an input impedance somewhere around 1000 megohms. By Leslle Solomon The circuit has unity gain, while the REJUVENATING ELDERLY EQUIPMENT upper frequency equalization is de­ termined by the setting of the 5000-ohm potentiometer. LTHOUGH most of us would circuit right into the old generator, tak­ The rise time is quite fast, and is A. like to purchase the best test ing the required power from the inter­ estimated at about half a micro­ gear that we can afford, we often have· nal supply. Any silicon switching second. The circuit was built on a nar­ to compromise when it comes to cost. transistors and diodes can be used. row pc board and mounted within an This means that many workbenches The input potentiometer (Rt) is ad­ old metal cigar tube container, as a may have test gear whose specifica­ justed for the best output waveform . probe. We have had no circuit loading tions are not much better than the Once set, this control requires no problems. equi.pment being tested . In which further calipration . Potentiometer R2 Although we have shown only a case, we may be violating one of the is used to set the output amplitude. couple of relatively simple ideas, there basic rules of good engineering (and Diode 01 protects the 02 emitter-base are many more. Where do these ideas servicing): test gear must be at least junction while· diodes 02 and 03 pre­ come from? When we receive our one order of magnitude more accu­ vent the clamp voltage from reverse quota of construction and ham rate than the device being tested . biasing. 01 . The input is driven from magazines, besides reading those ar­ In many instances, a few more years the maximum output of the old ticles that interest us, we take a look at can be squeezed out of the old gear square-wave generator. all the circuits, searching for ideas simply by " swiping" partial or whole Another piece of gear that needed that may sometime be useful. Once we ~ircuits out of magazines like POPULAR help was an old oscilloscope. Al­ see something that could be of use, we ELECTRONICS . Although most of us though it had the usual I-megohm im­ clip it out and file it in a set of folders never build even a small percentage of pedance, we found that it did load that are categorized by applications­ the various circuits we see, we should some of the newer circuits, especially audio, test gear, power supplies, etc. If take a close look at them with an eye where CMOS or bootstrapping were you don't like the idea of cutting up for ideas to improve our present test equipment. Over the past few years, +2ov------e-----­MAX we have found many circuits that 2.2K IOK

could be used to upgrade our test IN gear. The ,best part of this approach is Circuit (A) can be the very low cost involved. (The few used to improve hours of bench time required to as­ the waveform on a semble the circuits are actually enjoy­ square-wave generator; able when you're accomplishing while (BJ can be added something.) to an oscilloscope to Consider an elderly square-wave reduce input impedance. IK generator. This old timer might do

very well at the lower audio frequen­ -&v__..______~______,

cies; but as the frequency goes up, the (A) output square wave probably resem­

bles a badly warped triangle wave, at -----~INl"'------+15V · best. You can try to improve the high­ 68K frequency response by using the out­ put to drive some digital logic, such as a flip-flop. This would work, but you will need a 5-volt power supply, and the frequency will be halved. A Schmitt trigger circuit would probably work fine. However, you might want to try the circuit shown at (A). It converts the battered old waveform into an im­ pressive square wave with fast rise 62K IOOK and fall times, reaching way out in fre­ quency. The amplitude is also con­ stant over the entire span. We built this (B) 98 POPULAR ELECTRONICS magazines, then start a card file, re­ cording the title of the article, the magazine, the month and year, the page number, and the idea you have in mind. At some later date whe.n you are looking for help, all you do i·s look in your files under the proper"heading, find the article, break out the solder­ ing iron, and update.

Circuit Loading. Several times in the past, we have mentioned that measur­ ing voltage with a VOM is not the same as measuring it with a VTVM , VTM , DMM or any other high-input­ resistance instrument. Let us take the case of a circuit hav­ ing a 10-volt power supply and a series output resistance of 50,000 ohms. If you are using a VOM with a 20 ,000-ohm de resistance, the current flow through the circuit will be 10/ (7 x 4 10 ) , with the 70,000 ohms being the sum of the 50 ,000-ohm series resis­ tance and the 20,000-ohm VOM resis­ tance. The current is then 1.43 x 10- 4 amperes. The voltage drop available 1 to the VOM (1.43 x 10- ) (2 x 10 1) or 2.86 volts. The error is then (10-2.86)/ 10 times 100 or 71.4%. If you plug the VTVM 10-megohm input resistance into the above equa­ iions in place of the 20,000 qhms of the VOM, you will find that the current now becomes 9.95 x 10- 1 amperes. The voltage drop across the VTVM is now 9.95 volts, and the error is qnly 0.5%. llitlnfosh CATALOG You can use the de resistance of your own VOM and VTVM (or other and FM DIRECTORY high input resistance voltage instru­ Get all the newest and latest information on the new Mcintosh Sol­ . ment) to determine for yourself just id State equipment in the Mcintosh catalog. In addition you will receive an FM station directory that covers all of North America. how inaccurate those volt~ge mea­ surements have been in the past. You will see that the higher the input resis­ tance of the voltage measuring device, the greater the accuracy. ~

MX 113 FM/FM STEREO - AM TUNER AND PREAMPLIFIER ,------­ Mel ntosh Laboratory, Inc. --, I East Side Station P.O . Box 96 Binghamton, N.Y . 13904 SEND I Dept. PE NAME------'------­ TODAY! 1 ADDRESS------~ I c1Tv_____ sTATE.____z1p___ ------_.J If you are in a hurry for your catalog please send the coupon to Mel ntosh. For non rush service send the Reader Service Card to the magazine. CIRCLE NO. 23 ON READER SERVICE CARD JANUARY 1975 99 highly simplified manner. Short-answer, ~"'mli;;> multiple-choice questions and problems t~~ spend a conclude each chapter. Published by Prentice-Hal/, Inc., En­ ~m~ dime glewood Cliffs, NJ 07632. 462 pages. ~~ . · save a mint.'· $14.95, hard cover. Invest a dime and send for our catalog. Illt. We'll prove to you that you can DIGITAL COMPUTERS: have selection and convenience and Electronics Library still get a great price. CIRCUITS AND CONCEPTS by Deem, Muchow, and Zeppa For an immediate FREE copy ofour THE COMPLETE SHORTWAVE LISTENER'S This is a sophisticated text for the techni­ 64-page catalog, in­ HANDBOOK cian, engineering student, or practicing cluding pull-out engineer who wants to know how digital "Hifi Primer" sec­ by Hank Bennett systems operate, !ind how such systems tion, mail the coupon Here is a thorough, " hands-on" discussion below to the location can be designed at minimum cost and of all the facets of shortwave radio listen­ parts count. Among the topics covered are ~r::::r;rn~ 1i"i;-1 ing . The author, using his own SWL experi­ number systems, Boolean algebra, logic ence, and that of others, answers ques­ symbology, code and data representation, tions such as " What' SWL's hear, " " Why Karnaugh maps, and simplification of logi­ Wliiiiiiiii they listen, " and " How to get started ," cal expressions. Circuitry is not neglected. --­ among others. The purpose of the book is A thorough description of the RTL, DTL, to expose newcomers to the hobby, and to TTL, ECL and CMOS logic families is in­ ==Midwest provide the experienced listener with valu­ cluded. Shift registers, combinational and able information to hunt down new sta­ sequential circuits, decoders and encod­ tions. ers, timing and control operations are =:=:um The reader is introduced to the terminol­ analyzed and implemented to realize Wholesale ogy and the hardware of the hobby, as well mathematical operations in the serial and & MAIL ORDE R DIVISION as propagation phenomena. Tips are given parallel modes. Memories are given special . 1626 Ogden Ave. (US 34) , Downers Grove, Ill. 60515 on the selection of a receiver, installation consideration. 3309 E. Carpenter Frwy. (Texas 183), Irving, Tex. 75062 of an antenna, and times and frequencies for the reception of various parts of the Published by Reston Publishing Company, Box 537, Reston, Va . 22090. 376 pages. I NAME I world. The more exotic " sports" of FM and $14.95, clothbqund. I AD DR ESS I TV DX 'ing are given special attention. Chapters are also devoted to amateur and L•TV/STATE ZIP PE ·.5.01 J CB radio, logbooks, reports, card swap­ MODERN RECORDING TECHNIQUES CIRCLE------NO. 25 ON READER SERVICE CARD ping, and radio clubs. Perhaps the most valuable aid in the by R. E. Runstein book is a thorough list of foreign stations, This new work introduces the reade r to the by country, which includes exact frequen­ equipment and practices found in today's cies and times of transmission. There is multitrack recording studios. In the first also included a discussion of the DX pos­ chapter, the acoustical, mechanical. elec­ sibilities for the various frequency bands trical and magnetic means of transforming given the time of day, the season, and the a live performance! into a disc are outlined. point in the 11-year sunspot cycle. If you Later chapters describe consoles, mi­ are entertaining notions of involving your­ crophones, mixing, noise-reduction and self in shortwave listening, there are few monitoring. Finally, automated mixdown, sources which can whet your appetite as disc cutting and pressing, and quad­ well as this. raphonic disc systems are presented. Published by Tab Books, Blue Ridge Sum­ Published by Howard W. Sams & Co., 4300 mit, Pa . 17214. 281 pages. $.9.95 hard­ W 62nd Street, Indian polis, Ind. 46206. 368 cover; $6.95 paperback. pages. $9.95, paperback.

TRANSISTOR FUNDAMENTALS BASIC ELECTRICITY: ATEXT-LAB MANUAL AND SERVICING (Fourth Edition) by B. Larson by P. Zbar. The text covers the fundamentals of elec­ Designed as a programmed text for an in­ tronic devices to instruct readers in servic­ troductory electricity laboratory course, ing circuits and systems in which they are this volume presents basics of theory as found . Among the topics discussed are well as practical applications of electricity. diodes, power supplies, bipolar transis­ The reader is introduced to the passive cir­ tor~. bias circuits, ac amplifiers, FET's, cuit elements and their properties. Ohm's IC's, oscillators, vacuum tubes, and the os­ Law, series and parallel circuits, and vol­ cilloscope. Troubleshooting methods for tage dividers are ·explained with actual cir­ each of these components and networks cuits the reader can assemble. Kirchoff's are given. Packaging and conventions for Laws, Thevenin's and Norton's Tt)eorems, the various active elements are given. The and maximum power transfer are explored. emphasis in this book is on servicing, Time constants, reactive circuits, impe­ rather than design, with circuits reduced to dance, and ac analysis conclude the CIRCLE NO. 10 ON READER SERVICE CARD I the bare essentials and presented in a course. If the book is used as a lab manual, 100 POPULAR ELECTRONICS students who follow it should gain a basic working knowledge of electrical networks. Published by McGraw-Hi/I Book Co., 1221 Avenue of the Americas, New York, NY 10020. $6.95, soft cover. "mpzilla VHF HANDBOOK FDR RADIO AMATEURS by Herb Brier and William Orr · 1s l;ere... This guide to the "line-of-sight" frequen­ cies begins with a short history of vhf ex­ ploration and. experimentation. The most popular vhf bands include more than 13 MHz of spectrum space, more than four Why spend $750 to $1200 dollars for times the capacity of the hf bands. Since ___,,,__;,;.;.;;;;,...,;.__ _ ;,&, · 1a n amplifier? T he Great many amateurs are rnovi ng higher and q Amer ican Sound Company '. se ll s one with a full comple­ higher to avoid congestion and ORM, th is · ~ mentary series connected out­ book will be a valuable reference work for .! put for much less. In short newcomers to the high bands. Vhf propa­ JAMPZ ILLA is here. In the gation, caused by ionospheric reflection, ';September 1974 Popu lar Elec­ moonbounce, tropospheric, auroral, and , ! t roni.cs, H i.rsch-.Houck Labs ,says ... so lidly in the audio meteor effects is explained. The Oscar , -..!monster amplifier class . serie'! of satellites is examined, and special ··using 8 ohm loads ... TH D was less emphasis is given to earth-station config­ . than 0.01 % for all power levels ... up urations. The very popular FM scene, in­ to 200 watts . . '(per channel)' ... all in all we cannot imag ine a less expensive way of obtaining several hun­ cluding repeaters, mobile links, and tone­ dred watts.' Yes, we, your friendly GAS company, have the goods encoding controls is discussed. Design 'complete with a fan for ultra cool operation. Available with d irect mad­ theory and construction practices for an­ - ing power meters in kit ($375) or ful ly assembled ($525) . Also the tennas, solid-state amplifiers and receiving ''same amp but no meters in kit ($340) and assembled ($475). Write us for complete specs, or read Popular Electronics, September 1974. circuits are explained and illustrated. Published by Radio Publications, Box 149, Available directly from Wilton, CT 06897. 336 pages. $5.95, soft cover. THE GREAT AMERICAN SOUN'D COMPANY. INC. 8780 Shoreham Drive, West Hollywood, California 90069 ELECTRONIC TEST EQUIPMENT CIRCLE NO. 17 ON READER SERVICE CARD -AND HOW TD USE IT by J. Risse A guide to the practical uses and proper operation of test equipment, this book gives principles, functions, and applica­ Plug in...wire. tions for tube anc:l sem iconductor testers, signal generators, capacitance

SOLID STATE IGNITION SYSTEMS New Coot;"eotal Sp~~t~l~le as s3oo by R. Graf and G. Whalen SOCKETS® and BUS STRIPS · ·offer expanded, flexible bread­ Fundamentals of the various electronic ig­ i,, boarding without shorts or nition systems that are becoming more and kfh. burnt fingers. Simply SNAP/ FRee more popular in today's cars are dis­ tl 1 LOCK together as many METRIC cussed , and the conventional Kettering -~,.· QTs as you need and you TO '_.;I can test ICs, transistors, ENGLISH system is examined. Inductive-discharge 4· • resistors, capacitors and and capacitive-discharge using solid-state ;,"1 more. Just plug-in, connect SLIDE components are covereo by° describing Y with solid #22 AWG hook­ RULE repre~entative types offered by auto man­ up wire - no soldering or patch cords needed! And QTs Convert ufacturers and supply houses. Trigger lengths, area are totally ·reusable. 10 different methods: from breaker-point (with CDI) to Weight, volum~ sizes. Prices from $3 for QT Sock­ Instantly. magnetic " pointless" systems available as ets •. _ from $2 for Bus Strips. Yours FREE an option on most new American cars are With minimum Write or phone today for FREE Selection Guide, $5.00 order/ ihc; luded . with applications, photos, drawings, specs, socket sizes and ordering Information. Published by Howard W. Sams & Co., 4300 W 62nd Street, Indianapolis, IN 46206. 136 Continental Specialties Corporation =$=•• -­ • ;, • • • .44 Kendall St., New Haven , CT 06509, 203/624-3103 pages. $4.50. 11 . CIRCLE NO. 11 ON READER SERVICE CARD JAN~ARY 1975 101 SAVE! MONEY. • TIME • FREIGHT hr QUAL!TY STEREO EQUIPMENT CJ 1 AT LOWEST PRICES . .hr YOUR REQUEST FOR QUOTA­ fJ 1 TION RETURNED SAME DAY. hr FACTORY SEALED CARTONS­ fJ 1 CUARANTEEC AND INSURED. TONE CONTROL FOR BACKGROUND MUSIC hr SAVE ON NAME BRANDS LIKE : CJ 1 A.D.C. KLH Q. I purchased a low-cost, general· A.R. SHURE utility, solid-state preamplifier and DYNACO KOSS power amplifier (o supply back­ SONY FISHER groundmusic on myopen patio. Now' · AND MORE THAN 50 OTHERS find thi!lt ~ need some form ·of tone BUY THE MODERN WAY control to get a better sound. Is there BY MAIL-FROM a simple way to do this? A. The tone control shown here can be inserted between the preamp and the power amplifier. You will have to get the power supply from the a~plifier .

Department 217S -ev----. 12 ~ast Delaware ONE-TRANSISTOR PUSH-PULL OUTPUT RI Chicago, Illinois 60611 8 . 2K Is it possible to arrange a one­ 312-664-0020 q. transistor push-pull output to drive Cl~CLE NO. 18 ON-READER SERVICECARD two speakers~ne In the emitter cir­ cuit and one in the collector? A. This circuit can be used to drive a pair of 4-ohm speakers with a 1-watt output. Ad just the value of Rt to give the voltage drops shown across the speakers and the output stage.

the horizontal (external) input of the Write Today for Our A ONE-TIME SWEEP GENERATOR scope; and you can set the desired FREE Au~io Catalog Q. I need some kind of r-f sweep sweep rate with the potentiometers. DIX IE is one of t he oldest and largest aud io compo· generator to align the i-f of a receiver nent mail order ho uses in the country. Our prices on The varactor can be any one in the brand name components are actua ll y LOWER th8n I built. I have no need for a commer­ " Discounters" . ·See our new catal og or ca ll uS for a range of about 50 pF. Use a Miller 9003 price quote. Everyth ing shi pped factory-sealed wit h cial unit-just something simple for full man ufacturer's warr anty. · coi I with a range of 380 to 1000 kHz for this one-shot alignment. ~ 455-kHz i-f or a Miller 4505 (10 to 14 [• , •J • m ~ f•"u' • ~o~ A. You could try the basic circuit MHz) for a 10.7-MHz i-f. Other coils M1n1r Ch1r111 I BankAm1rlc1 rd shown here. The UJT OL!tput goes to honored on mill orders can be used for other ranges.

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NON·DISPLAY CLASSIFIED: COMMERCIAL RATE: For firms or indfviduals offering commercial products or services, $1.80 per word (including name and address). Minimum order $27.00. Payment must accompa'1y copy except when ads are placed by accredited advertising agencies . Frequency discount; 5% for 6 months; 10% for 12 months paid in advance. READER RATE: For individuals with a personal item to buy or sell, $1.10 per word (including name and address.) No mi nimum! Payment must accompany copy. DISPLAY CLASSIFIED: 1" by 1 column (2-1 /4 " wide), $215.00. 2 " by 1 column, $430.00. 3" by 1 column, $645.00. Advertiser to supply cuts. For frequency rates, please inquire. GENERAL INFORMATION: First word in all ads set in bold caps at no extra charge. All copy subject to publisher's approval. All advertisers using Post Office Boxes in their addresses MUST supply publisher with permanent address and telephone number before ad can be run . Advertisements will not be published which advertise or promote the use of devices for the surreptitious interception of communications. Closing Date : 1st of the 2nd month preceding cover date (for example, March issue closes January 1st. Send order and remittance to POPULAR ELECTRONICS,-One Park Avenue, New York, New York 10016, Attention: Hal Cymes.

CONSTRUCTION PLANS: Laser ... $2.00. Rocket Tracking HEAR POLICE/FIRE Dispatchers! Catalog shows exclusive FOR SALE Transmitter ... $2 .00 . Space Moni to r-Missile directories of " confidential " channels, rece ivers. Send 10 Tracker. .. $2.00. Free Catalog . Electro-Research , P.O. Box cent stamp. Communications, Box 56-PE, Commack, N.Y. 20285, Ferndale, Michigan 48220. 11725. FREE! Bargain Catalog-1.C.'s, LED's, readouts, fiber CD IGNITIONS, VHF/UHF monitors, crystals, CB rad ios, CONVERT any television to sensitive, big-screen osclllo­ ~~:~c~a~:.1c~~t~:2~~.rt~y~nl~:~ : ~ea~~~o0~~~~tors, parts. Southland, Box 3591-B, Baytown, Texas 77520. :~~~~~n~;'~e~~~~;rych1 ~~~t~!t::~~~:.. $~~ ~,~~~~:r~~ GOVERNMENT Surplus Receivers . Transmitters, Dept. A-33, Box 92102, Houston , Texas 770100. Snooperscopes, Radios, Parts, Picture Catalog 25 cents. Meshna, Nahant, Mass. 01908. YOU WILL SAVE BIG MONEY! Surplus, Clearouts, HA 5,, . Bankruptcy, Inventory, Deals. Catalog $1 {redeemable). LOWEST Prices Electronic Parts. Confidential Catalog ETCOA Electronics, Box 741, Montreal, H3C 2V2. U.S. Free . KNAPP, 3174 8th Ave . S.W., Largo, Fla . 33540. ® modular Inquiries. ELECTRONIC PARTS, semiconductors, kits. FREE FLYER . SYNTHESIZER BURGLAR-FIRE alarm supplies and information. Free Large catalog $1 .00 deposit. BIGELOW ELECTRONICS, catalog . Protecto Alarm Sales, Box 357-G, Birch Run , Bluffton , Ohio 45817. Michigan 48415. RADIO-T.V. Tubes-36 cents each. Send tor tree catalog. KITS COM PLETE CONSTRUCTION PLANS-TELEPHONE: Cornell, 4213 University, San Diego, Calif. g2105. Answering Device. 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DIP .69 ALL DUAL-IN-LINE 1301n UOIOWAY ATV Research DAllOtA cnY, NISR . 68731 7427 .35 74145 1.15 741 Comp. op amp mDIP .35 7430 .22 74150 1.09 747 Dual 741 DIP .79 7432 .29 74151 .89 MEMORIES DIGITAL ELECTRONICS: Complete schematics, parts 748 Freq adj741 mDIP .39 7437 .45 74153 1.29 1458 Dual Comp op amp mDIP .69 7438 .39 74154 1.59 1101 256 bit RAM MOS $1.75 lists, theories - Discrete Component Digital Clock, 3900 Quad amp DIP .65 1103 1024 bit RAM MOS 4.95 $3.00 - Sound Sensitive Switch , $'1 .50. Increase technical 7440 .19 74157 1.29 3905 Pree. timer DIP .65 7441 1.09 74161 1.39 5260 1024 bit RAM low power 3.95 competence , hobby skills - Complete Course in Digital 8038 Function gen. DIP 5.95 7489 64 bit RAM TTL 2.75 7442 .99 74163 1.59 75451 Dual prl. driver mDIP .39 Electronics is highly effective, $10.00. Free literature. 7443 .99 74164 1.89 8223 Programmable ROM 4.95 75452 Duel prl. driver mDIP .39 74200 256 bit Ram·tri·state 7.95 DYNASIGN , Box 60A7, Wayland, Mass. 01778. 7444 1.10 74165 1.89 75453 Dual prl. driver mDIP .39 7445 1.10 74166 1.65 MECHANICAL, ELECTRONIC ·devices catalog 10 cents. 75491 Quad seq driver DIP .79 7446 1.15 74173 1.65 75492 Hex dig. driver DIP .89 LED'S AND OPTO ISOLATORS Greatest Values - Lowest Prices. Fertik's , 5249 " D", 7447 1.15 74177 .99 OatashfMl$SYPflli9donreqoes1 MV10B Red TO 18 $ .25aa. Philadelphia, Pa. 19120. 7448 1.15 74180 1.09 Add S.50 fOf itams Ins tNn Sl.00 7450 .24 74181 3.65 MV50 A)Cial leads .20 SOUND SYNTHESIZER KITS-Surf $12.95, Wind $12 .95, 7453 .27 74182 .89 MV5020 Jumbo visible red .33 ME4 Infra red diff. dome .60 Wind Chimes $17.95, Electronic Songbird $6.95, Musical 7454 .39 74190 1.59 CALCULATOR & CLOCK CHIPS w/data 74193 MAN1 Red 7 seg..270" 2.50 Accessories, many more. Catalog free . PAIA Electronics, 7460 .19 1.39 5001 12 DIG 4 funct fix dee 3.95 7464 .39 74194 1.39 5002 Same as 5001 exc btry pwr 7.95 MAN2 Red alpha num .32" 4.95 Box J14359, Oklahoma City, OK 73114. · 7465 .39 74195 .99 5005 12 DIG 4 funct w/mem 8.45 MAN3A Red 7 seg. .127" .79 7472 .36 74198 2.1 9 MM5725 8 DIG 4 funct chain & dee 2.79 MAN3M Red 7 seg. .127" claw 1.15 7473 .43 74199 2.19 MM5736 18 pin 6 DIG 4 funct 4.95 MAN4 Red 7 seg. .190" 2.15 DISCOUNT PRICES MAN5 Green 7 seg..270" 2.95 0 111 lhHU wpptiod on •1qont MM5738 8 DIG 5 funct K & Mem 7.95 B & K, SENCORE, LEADER and RCA Ad.cl S.50 tor lt•ms less th&o $1.00 MM5739 9 DIG 4 funct (btry sur) 6.95 MAN7 Red 7 sag. .270" 1.35 MM 5311 28 pin BCD 6 dig mux 6.95 MANS Yellow 7 seg..270" 3.95 Test Equipment MAN66 60" high dir. view 4.65 CMOS MM 5312 24 pin 1 pps BCD 4 dig mux 6.95 RAYTHEON, ICC / MULLARD Tubes MM 5313 28 pin 1 pps BCD 6 dig mux 7.95 DL707 Red 7 seg..3" 2.15 TELEMATIC Test Jigs 74COO $. 39 74C42 2.15 MM 5314 24 pin 6dig mux 8.95 MCD2 Opto-iso diodes 1.09 74C04 .75 74C76 1.70 MM 5316 40 pin alarm 6 dig 8.95 MCT2 Opto-iso transistor .69 Free Catalog 74C08 .75 74C173 2.90 74C10 .65 80C97 1.50 FORDHAM RADIO SUPPLY CO., INC. ON ORDERS OVER $25.00 DEDUCT 10% • 558 Morris Ave. • Bronx, N.Y. 10451 • 4000 SERIES RCA-EQUIV. All items are new, unused su rplus parts - tested functional. CD4001 $ .55 CD4017 2.95 Satisfaction is gua ranteed. Shipment will be made via first class CD4009 .85 CD4019 1.35 mail - postage paid - in U.S., Canada and Mexico within three FREE CATALOG. Parts, circuit boards tor POPULAR CD4010 .85 CD4022 2.75 ELECTRONICS projects. PAIA Electronics, Box 014359, days from receipt of order. Minimum order - $5.00. California CD4011 .55 CD4023 .55 ,, residents add sales tax. Oklahoma City, OK 73114. CD4012 .55 CD4025 .55 CD4013 1.20 CD4027 1.35 (408) 659-4773 INTERNATIONAL .ELECTRONICS UNLIMITED CD4016 1.25 CD4035 2.85 P.O. BOX 1708 MONTEREY, CALIF. 93940 USA

JANUARY 1975 CIRCLE NO. 19 ON READER SERVICE CARD 103 CRYSTALS, Scanners. $3.88, include make and frequency. CARBON FILM RESISTORS. Brand new as low as 2-1 /4 FREQUENCY COUNTER for under $75. 00; provisions to G Enterprises, P.O. Box 461 PC, Clearfield . UT 84105. cents . FREE samples and specifications. COMPONENTS 200MHz, Nixie or LED readout 8 digit; uses standard IC 's, FREE CATALOG . Kits , Components . audio equipment . CENTER- PE , Box 134, New Yo rk, NY 10038 . complete details $3.00 , postpaid. East Coast Electroriics, Electronic Supply Pacs. Box 175. Floral Park N.Y. 11 001. 7.000 SEMI CONDUCTOR S. 100 's El ectronic Circuit Kits , 50 Scott , Hamburg, New York 14075. PRACTICAL App lications of Digital IC's . tOO 's of tips , Technical Reports, Energy Co nservation. Computers. Cat. COMPUTER countless uses. 8 E>i t word , powerful instruc­ circuits, projects. on TTL. 443pp $t9.95. Money Back 50 cents. E/S Lab , Box 738, Co llege Park. MD 20740. tion set. Complete $225. Broc hure 10 cents. RAECO , Box Guarantee. GEA. P.O. Box 285, Northfield, Oh io 44067. UNSCRAMBLER S: Fits any scanner or monitor. easi ly 14, Readvi lle, Mass . 02137. ALPHA/THETA BRAINWAVE biofeedback instrume nts . adjusts to all scramb led frequencies. On ly 4" square TEN Batteries 1-1/2V. Send $2 for batteries and price list. Analog instruments from $125; digital processing systems $29 .95, fully guaranteed . Dealer inquiries welcomed. PDQ Electronics, Box 33071 , District Hts .. MD 20028. from $225. BioScan . Box 14168-E. Houston. Te xas 77021. El ectronics, Box 841 , North Little Rock, Arkansas 72115. ELECTRONI C SURPLU S 1974 Catalog 25 cents . Refund ­ SURPRISE! Build inexpensively. the most Unusual Te st LE ARN DESIGN TE CHN IQUE S. Electronics Monthly able w/o rder . At lantis. Box 12654P. Tucson , AZ 85711. Newsletter. Digital. linear construction projects, design Instruments . Futurist i c Gadgets using Numerical theory and procedures. Sample copy $1 .00. Valley West , Reado4ts! Catalogue Free! GBS, Box 100A. Green Bank. SUBSCRIBE NOW: West Virginia 24944. Box 2119-B, Sunnyvafe, California 94087. ELECTR ONIC ORGAN KI TS, KEYBOARDS and many BURGLAR-FIRE ALARM compo nents. hard ware. Free ~E~RN THE SECRETS OF YOIJR TELEPH~" components. Independent and divider tone generators. All Catalog- In formation. Si lmar, 133 S. W. 57 Ave .. Miami , diode keying . l.C. c irc uitry. Supplement your Artisan Florida 33144 . Organ, 35 cents for catalog . DE VTRON IX ORGAN WE SELL MONEY MAKING CO NSTRUCTION MANUALS '!' PRODUCTS. Dept. C .. 5872 Amapo la Dr .. San Jose . Calif. - Reclaim GO LD . SILVER for EXC ELLENT lu ll or part time 95129. money!!I - PLUS. we buy scrap gold & silver- ALSO. we ELECTRONI C IGNI TI ON : Capacitor. transistor. pointless. sell 99.999% pure SILVER BARS!ll - Co lor Catalog 25 Auburn sparkplugs. Information 10 c ents. Anderson cents - Airmailed 50 cents - Cre ative Products, De pt. Engineering . Ep som , N.H. 03234. PE-175, 4913 Northridge NE , Albuque rq ue. New Mexico 87111 . WHOLESALE Scan ners. CB , Cryst als. Di rectories . SSS /AM, catalog 25 cents. G- En terprises . Bo x 46 1P. DIGITAL IC Manu al-Latest Ed ition-1 500 types by Clearfield . Utah 84105. types/diagram number $3.95. 32-function digital Stories • History • Comics • Facts • Games computer kit- IC , transistors , instructions. $14.00. IC 1 1 CALCULATOR OWNER$: Use Your + -x...;- calculator to appli cations manual-numerous circuits- Analog /Digital. '1 Code Numbers • Projects • And Many More compute squaie roots, trigonometric functions. logarithms , $3.95. El ectronetics. P. 0 . Box 127, Ho peda le , Mass. 01747. ll - One ~·ear subscription only $ 3.00 ­ an~ more! Ouickly, Accurately, Easily! Send today for the L ETRONJCS --- _..... - P.0.80X3411 ~ firSt and Best Calculator Manual now in use through­ AMEllCA 111111!1 ..__ LOS ANGELES, CA. 90029 ' qut the world ... still on ly $2.00 Postpaid with Uncon­ ALPHA/TlnTA BRAINWAVE ~~~~ ditional Money-Back Guarantee ! Ma11mann Optics and BIOFEEDBACK INSTRUMENTS The only biofeedback instruments ava il­ DESCRAMBLERS several models that work with all Electronics. Dept . 23A, 836 South 11 3. West Allis. scanners and tunable receivers. Automatic Activated Wisconsin 53214. (} able with powerful built-in digital pro· f'.l '"' cessing. AlphaScan 400 shown at $225; Phone Patch , Proximity Alarm Kit. Telephone Scrambler FREE 1975 Electronics Catalog. McCord Electronic s. Bo x ... .. ,o.,..:;,.. tf others fmm Sl 25-S795 . Write for free Kit. Tone Signaling Kits. Jinni-1 Sem iconductor Tester with 276-N , Sylvania, Ohio 43560. ' -~~ literature including our booklet, "Some LED readout indicators, other k its, parts, plans. Catalog 25 AUTORANGING DMM , deluxe VOM's , logic probes and Techn ical Considerations for EEG Biofeedback lnstrument> tions." cen ts , KRYSTP.~ KITS. Box 445. Bentonville, Ark . 72712. mOre. Lowest prices. Free catalog . Electro Industries. 4201 BioScan Corporation, Bo x 14168-E, Houston, Tex. 77021 ELECTRONICS parts, low prices, free flyer: DARTEK Irving Park , Chieago, Illinois 60641 . "EL ECTRONIC INSTRUM ENTATION FOR THE LIFE SC IEN CES" ELECTRONICS, Box 2460, Dartmouth , Nova Scotia, Canada. U.S. Inquiries. ARE YOU PREPAR.ED? 10,000 cu bi c foot . pull ring ignited ELECTRONIC COM PONENTS-all kinds , send for free emergency Smoke grenades are now available! 3 for $7.50. catalog. Epic. Box 20152A, Minneapolis, Minn . 55420 . WHO LESALE BURGL AR ALA RM supplies. Catalog $1.00 9 for $20.00. Postpaid . Pacific Aero Supply. Box 601 , (refu ndable). Ellin . 161W Bonad , Chestnut Hill , Mass . Malibu, Calif. 90265. QUALITY military and industrial surplus electronics. Send 02167. 25 cents for last 3 of our monthly picture flyers. US only . PYROTECHNICAL chemi cals, casings. too ls, supplies. Startronics. Bo x 17127, Portland. OR 97217 . ELECTROEN CEPHALOPHONE/Brain activity co ntrol. Z.J. fuse . Price List 50 cents. Westech. Logan. Utah 84321 . COM PUTER SCHEMATICS . 256 bits, expandable to Daszewski Lab .. 36 1 Garretson Ave .. Perth Amboy, N.J. TELEPHONES UNLIMITED, equipment. supp lies . Catalog several K. Many other schematics avai lab le. SP 08861 . Tel: (201) 826-3061. Please send 25 ce nts or se ll­ 50 cents . Box 1654E, Costa Mesa . Calif. 926 26. Electronics. Box SE. Prospect Heights, Illinois 60070. addressed envelope with inquiry .

7400 $ .18 74182 .89 LM300 LINEAR $ .79 7401 .19 TTL 74184 2.30 Christmas SPECIALS LM301 H/N .30 7402 .i9 7475 .75 74185 2.19 LM302H Voltage Follower .75 7403 .19 7476 .47 74187 6.00 LM304H Negative Volt Reg 1 .1 O Digital LCD Watch H04 .21 7480 .50 74190 1.50 LM305H Positive Volt Reg 1.00 7405 .22 7482 1 .75 74191 1.50 ;~ , Liquid Crystal Display LM307H/N Op Amp (Super 741) .35 7406 .39 7483 1.11 74192 1.35 Constant on-Shock Proof LM308H/N Micro Power Op Amp .99 L 7407 .39 7485 1.10 74193 1.35 I s:4s\ . uses Field ·effect display LM309K 5 Volt Regulator/Amp 1.25 7408 .25 7486 .44 74194 1.39 Accuracy to 1 Minute' a-Year. LM31 OH Improved Volt Follwer 1 .35 7409 .25 7488 3 .00 74195 .95 ~' LM311 H/N Hi-perform Volt.Comp. .89 7410 . 19 7489 2.75 74196 1.25 5 Year Warranty $149.95ea LM318N Hi-Speed Op Amp 2.00 7411 .29 7490 .79 74197 .99 .Ml! Unassembled Kit · 99.95ea LM320K To 3 Neg. Regulator 1.50 7412 .40 . 7491 1.29 74198 2.19 California Res.· Add 6% Tax LM324N Quad 741 Op Amp 1.75 7413 .79 7492 .79 74199 2.19 USA MADE LM339 Quad Comparator 1.65 CALCULATORS 7416 .39 7493 .79 74200 6.95 LM340K Positive Volt Regulator 1 .89 7417 .39 7494 .89 5m8-4 Function 9V $29.95 LM370N A 6 C - Squelch Amp 1 .55 7418 .25 7495 .89 CMOS 6 Month Warr. Red Led ea LM373N AM/FM $$ B Strip 3.30 7420 .19 7496 .89 CD4001 $ .55 SL8M-4 Function Memory $53.00 LM380N 2 Watt Audio Power Amp 1 .15 7421 ,35 74100 1.50 CD4002 .55 %-Add (ln Disc.-Tilt Lens ea LM555N Timer .75 7423 .35 74107 .47 CD4007 1.25 LM565-LM566-LM567 Phase L.L 2.00ea 7425 .39 74121 .55 CD4009 .85 5m-20-5 Function Memory$39.95 , Constant-9V-1 Yr.W. ea LM703H RF/IF Amp .45 7426 .29 74122 .47 CD4010 .65 LM709H/N Op Amp .29 .35 74123 .99 CD4011 .55 7427 - ~ -----=- TIME-Temp Display LM723H/N Voltage Regulator .55 7429 .40 74125 .60 CD4012 .55 ' / 11 ;( 6 digit LED Display LM741H/N Comp: Op Amp .30 7430 _22 74126 _79 CD4013 1.10 ; 1<:J,. J~ Liquid Crystal Temp. Display LM747H/N Dual Campen.Op Amp .79 I ~-- 7432 .29 74141 1.15 CD4016 1.25 1 115 Volt-1 Yr. Warr. $39.95 LM748N Freq. Adj. 741 .40 7437 .45 74145 1.10 CD4017 2.50 IC sockets -Kit from $29.95 LM1310P Stereo Demodulator 3.50 7438 .39 74150 1.05 CD4019 1.25 LM1458N Dual Comp. Op Amp .65 8 pin DI L .22 36 pin DI L 70 PROJECTS 7439 .50 74151 .89 CD4020 1.50 1. LM1556N 5TimesFaster741 1.85 14 pin DI L .26 40 pin DI L 1.90 8263 $ 7.00 7440 .19 74153 1.29 CD4023 .55 LM2307P Current Controlled 05 Cit. 3.15 1.25 CD4025 .55 •16 pin OIL .29 WIRE WRAP 8267 4.00 7441 1.08 74154 LM3065NT.V.-FM Sound System .75 18pinDIL.46 LEVEL#3 2513 12.00 7442 .99 74155 1 .19 CD4027 1.25 LM3900N Quad Amp .50 7443 .99 74156 1.29 CD4030 .60 22pinDfL .65 14pinDIL .46 2518 7.00 LM3905N Precision Timer .65 7444 1.10 74157 1.29 MC3022 2.00 24 pin DI L .68 16 pin DI L .55 2524 6.00 LM7522 Core Memory Sense Amp. 2 .50 7445 1.10 74160 1 .65 74COO .35 28 pin DI L .99 24 pin DI L 1 .05 7805 2.00 LM7524 Core Memory Sense Amp. 1 .50 7446 1'.10 74161 1 .39 74C04 .69 Satisfaction Guaranteed. All Items 100% Tested LM7535 Core Memory Sense Amp. 1.00 7447 1. 10 74163 1.59 74C20 .65 $5.00 Min. Order - 1st Class Mail - No Charge LM75451 Dual Peripheral Driver .49 7448 1.10 74164 1.89 74C173 2.50 California Residents - Add 6% Sales Tax LM75452 Dual Peripheral Driver .49 7450 .24 74165 1.89 Wholesale Outlets - Write for S~ial Discounts LM75453 Dual (LM351) .65 7451 .27 74166 1.65 8000 SERIES 7453 .27 74170 3.00 8091 .59 ..,..,.,..,..,L~D_S_-1powER SUPPLy KITS 7454 .39 74173 1.65 8092 .59 MV10 5 / 1 Variable Power Supply 1.85 8095 1.39 7459 .25 74174 8123 1.59 MV50 6/1 5 to 25 Volt 1 Amp 7460 .19 74175 1 .85 8130 2.19 MV5024 5/1 Less Ch~ssis . $19.95...Qer Kit 7470 .45 74176 .89 MAN-1 1 g5 FIXED POWER SUPPLY 8200 2.59 · 1 Amp - Specify one of the 7472 .36 74177 .89 8210 3.49 Jl/NE~ MAN-3 .95 ten available voltages plus 7473 .43 74180 1.05 8223 4.00 P.O. BOX 822, BELMONT, CA 94002 MAN-4 1.95 Plus Voltage: 5-6-12-15-24 7474 .42 74181 3.50 8288 1'15 8520 1 .29 MAN-7 1.00 Minus Voltage: 5-6-12-15-24 20% Discount for 100 :ss26 s.oa D L33 1.95 Less - Chassis $16.95 per Kit Pieces Combined 7400 8880 1.33 o~~~~~ (4161 692-8097 DL747 2.50 104 . CIRCLE NO. 20 ON READER SERVICE CARD "ALL LED" MONSANTO THE SIMPLEST! FINEST! SMALLEST! READOUTS rllll '­ 6-FUNCTION AC-DC ~2 Sf)l CALCULATOR KIT! ~ 4 • ~ ~~ ~ll!N . 6~ MAN-64 • Lightweight, pocket size • True credit "balance . CHAR. SALE . Quantity Extra large display • Slmpllfied Indexing HT. EACH Discounts ...... ~. • 8 functions plus, minus, • Merk up and Mark down MAN-1 .27 3 for$ 9. 20-Yeus of Mo1tey·B•ck times, percentage, constant• Constant multlpllcatlon -2 3 • 4 GUARANTEES ,;.llliilliil~· • Floating decimal and division MAN- 3 . 12 3 for S 2.50 20-Years of Eco•omyl •W•lllJli•!'!ll •Chain and Mix calculations • AC adaptor jack MAN· & ,60 3 for 12, LOWIEST _."ICES! l Designed specifically for P oly Paks under the Daltone MAN-64 .4 3 for $ 9 . 80 brand. IMAGINE! only 2112 x l x 411z 11 • Slides easily MAN · 7 .27 3 tor$ 3. 48-HR. SERVICE into your vest pocket, brief case, or handbag. We • 35 LED matrix hunted everywhere to find a calculator kit that can be small, do the many functions, with fine engineering design and SIMPLE TO BUILD! WHY? Because it bas the fewest parts in a kit. Imagine the pc board only has the chip, 4 resistors, two transistors, two driver ic's with the 9 digit readout. SIMPLE! You bet it is. The entire kit is even packed in a multicolor attrac­ tively designed b ox that in itself tells the mini calcuta. tor stor y. Kit includes: attractive black case with red filter; Flex Key (type 20SK-66) 1 8 key keyboard that measures o nl y 21/z x 2" with 2 switches, o ne for ON­ OFF, one for K constant; MAIN pc boa.rd : readout board; famous Cal Tech 5030 26-pin calculator chip; NATIONAL two 75491 ic drh•ers; Hewlett Packard 9 digit array: ac jack; 9 Volt batter y connector resistors; two tran­ LINEAR o$29.9S sistors; back protective plate; necessary wire plugs; OP AMPS Buy 3 for $7S. --=====:..; easy instructions. ( Less 9 v.,lt standard battery and 0 LM-309K 1.50 c.... PC board• AC adapter) EASIEST KIT TO BUILD 0 LM-319 1.19 0 LM-320 1.25 0 LM-340 2.50 1 0 LM-380 1.39 GET KEY THE PARTS! ~::~~ar~~T ta~ Tuc~ncbu.;t;oo~as~a1~~ i:~;rct~h~p~ ~~d~;i; 0 LM -381 1 : :~ First time ever offered! Mini design makes this unit 8 t: : ~g~M 2 1 CASE ~~'~(:~!:;· :~P: .::: :~;:~::. ;::;v~::::t ~::~~~:f! 0 LM-709 :~~ =~hg~fblj~!~ !~";:~~ s N~tf~~;3 :1~~k~~ip~~b~id aa1::od~?~:d chip is National 8·digit MM5725 . O $16.95 0 LM-710 , z9 C?J?struct.1on. Easy to read numbers. Three pressure sen· BASIC KIT 0 3 - same as Basic /Jl except calculator 0 LM-711 .29 s1t1ve ~witches, for .HOLD, HOURS. SECONDS 12 or 24 Calcul81Dr 0 LM-723 0 c hip is National 6-diglt MM5736 and 75492. O $16 .95 61 h~ur s m rear of uni~. THIS IS NOT A KIT! Completely :;: _wired r ~ady to, go. Size: 5 x 2 x l l/z ". Gift boxed, With 1 12 DIGIT BASIC Ji4 - Key parts include: C'f6 001 80 LM-741~= = ~~~ •31 ~~sct{eu~~~~atf~~~e booklet. Wt, lf2 lb., 11 0/VAC. 60 0 LM-741CV ~~~fi~; 3 g!~~~ r2~~~~its8io~ac!~~~::~:.ed d~~i:~j~·~~~~h: 8 ~==:~:: 1 Wild Rover Keyboard with ON-OFF switch diagrams. 0 LM- 1307 :;::~~ ~---'•------'35 WATT AUDIO 0 $3.98 . ~ Sale $24.95 D 0 LM- 1458 .99 AMPLIFIER BASIC 2 for $ 7 ~r 8-DIGIT MINI CALCULATOR BASIC KIT # 6 - world's 0 LM- 1496 ::: For Class AB use. Basic includes: Signeuc U L.M-3028 1 ~~ smallest. Needs least amount of components to complete 0 LM -3900 kit. Includes CT·5030 chip, mini case, with lens, ke~·- 0 LM-4250C 2::: ~:,g.. ~~f~~ n:is;~fr ~~h c~~";~~e~~·::YT~S~ 1 ~~dr:it \\~;~a~n·{3e!l:ttcop;~k"a~J )'.i t¥~~fu!spedfae:rt:~:: .88 ~8Jt2~ ~~~ ~~~·~~~~ici·:~a~~c~~~~in~~~ ,d rv'<>~ 0 555 0$19.95. 0 562 ~:= circuit and parts board layouts. .q't-' / 11 0 565 8-DIGIT TEXAS INSTRUMENT" BASIC KIT i/7 ­ D sea 2 .so BRAND NEW LOWEST PRICES 0 includes Texaskeyboard, 1KS14 9, standard 4-function. D 567 With T-1 calculator chip TMS-0128, p .c. board, case, D RC4195 ~.~~ :~:~:~..~Lt:CTRI~ :.;:-'~TJ. $2.50 lens. Microswitch (on·off). 9 -digit ANTEX array; in· 0 4139 l.91 Delivers 3.5 wstta continuous, 10 watts peak. \V1tn e ludes diagram, $19, 95. O beat ainks: micro-mini size: 3/4 xl/ 2xlf2". 9 to 30V sup­ MINI CALCULATOR BASIC KIT JI B - 4-Function S:\me ply. High sensitivity, 8 to 16 ohms. as KIT i! 6 except less pcrcent:lJ:rt! and constant. Includes CT·50~ll chip, D $17.95. SSS CLOCK CHIPS as Lo w as $6.99 TIMERS ON A "DIP'' WITH DATA SHEETS D ANY CASE for above Calculator Basics $2.50 3 fOf" $6. 2 u Seconds 0 ll!M5311 · &·digit 28·Pln $6. 99 to 1 - hr. 0 MM5312 4·di&it 24·Pln 6.99 CALCULATOR ACCESSORIES (Mini DIP) D Texas Instrument Keyboard . , ..... $6.95 3 for $18. B==:~~~ ~::=:: I D Wiid Rover Keyboard ...... , , $6.95 3 for $18. o 2 for $1 O MM5316 :4-digit:::::: 40·Pln, alarm :6 :.::99 D P.C. Boards "stated" In above kits . $2.SO 3 for S 6. Sale good till O MM5316-A no alarm 3.95 AC ADAPTERS FOR CALCULATORS 0 CT7001 4· 6·dlg;t s 9.9S Feb . 15, 1975 Alarm & Calendar O 9-Volt Charger & Converter ...... $2.95 3 for S 7. D 1.2 VDC @ 2A for Nlcad Batteries . $2.95 3 for S 7. LC:,':E:i:.:~c:~ 'CALCULATOR CHIPS' O CT 5001 12·Disits . 40 pin ...... $4.95 3 for $12. O CT 5002 9-Volt version of 6001 6.50 3 for $18. O CT 5005 12·Digits, 2 8 -pin, with 3-function memory 7 .50 3 for $21. O CT 5030 4-Function w ith % 9.95 3 for $24, D CT 5031 4 ·Function Only 6 .95 3 tor $18. D TMS-0128 4-Function by Texu.. . . 9 .95 3 for $24. I O MM 5725 8-Digits, 4 · funct. LED . 4.95 3 for $12. f/ Firir;i,S736A:;t·~:-:;~:~ , . • :~ ::12. t/TimQJJ. iill£~is% TAKE 25% Ecd'ti'O'Air-fW"l1;,7ci:s Type Sale Order by t)'pe number~ S11ec sheets on renuest " O!'llL\"" • Factory Marke d 0 SN7400 $.19 0 SN7430 .24 0 SN7472 .42 0 SN74107 .49 0 SN74161 1.59 0 SN7401 .19 0 SN7432 .28 0 SN7473 .52 0 SN74108 .95 0 SN74163 1.75 4 WATT GUITAR AMP S~L~TATE 0 SN7402 0 SN7403 :~: B ~=~:~~ B ~=~:;: :~~ B ~:;:~ ~~ ::~ B ~=~:t:: ~::~ With Tremolo 0 $7.95 AMPEREX 0 S.N7404 ::: 0 SN740S :~I B~:;::~ 1:~g B~:;:~: :~~ B~:;:~~1 ::: 8 ~:;:f ;~ f::: Musical instrument amplifier at low, low price! Peak SN7406 power output 1 0 watts. Two input circuits are equal. 0 0 5N7407 : ~: B ~:;::~ ~:gg B ~:~::~ 1:~: B ~=~:f~~ 1:g; 8 ~:~:~~: ~:~: ized for normal or solo guitar. The four controls are 0 SN7408 ,27 0 SN7444 1.00· 0 SN7482 .99 0 SN74125 .65 0 SN74176 1 .25 0 SN7409 .27 0 SN7445 1.00 0 SN7483 1.19 0 SN74126 .89 0 SN74177 1.25 ~~i~~E!fh~?eN~~:!i~!i~ ~~5J~!r S:o~~~o~~~ 0 SN7410 .19 O SN7446 1.10 0 SN748S 2.50 0 SN74139 1.25 0 SN74180 1.10 foot switch connection, Supply voltage l Svdc. Output 0 SN7411 8 0 8 3 0 SN7412 :~~ 8 ~=~::~ ~:~~ 8 ~=~::: £;: 8 ~=;:~:~ t~~ g ~=~:~=~ ~:g: ~hm s. ~~rr1!:~~u~~~i~ ~~a:~·s.lnf~:e~~e~~:!r :Jg~~ 0 SN7413 .89 0 SN7450 .27 0 SN7490 J . 81 0 SN74145 1.19 0 SN74185 2 .34 required. Wt. l lb. With instructions, hookups and 0 SN7414 2.25 0 SN7451 . 28 0 SN7491 1.35 0 SN74148 2 . 95 0 SN74187 2.34 diagrams. Size 8 x 25/s x 3. 0 SN7415 1 0 SN7416 ::~ B ~:;:~: j; 8 ~:~:;; ::: B ~:;:~:~ : ~: 8 ~:~:~;; t~; 0 SN7417 .so 0 SN7455 .28 0 SN7494 1 . os 0 SN74153 1.39 0 SN74194 1.89 60-WATT STEREO 0 SN7420 .22 0 SN7460 .26 0 SN7495 .99 0 SN741S4 1.69 0 SN74195 1. 10 0 SN7421 .SO 0 SN7461 .26 0 SN7496 .99 0 SN741SS 1 . 29 0 SN74196 1.20 HIGH FIDELITY •Wall ..s1;m·Llne.. Type! 0 SN7422 .29 0 SN7462 .39 0 SN74100 1.55 0 SN74156 1 .45 0 SN74197 1.10 0 SN7423 . 32 0 SN7464 .39 0 SN74104 1 . 25 0 SN74157 1.45 0 SN74198 2.45 AMPLIFIER • 1a:~s~::1°~~s~:~rne:;.t~~ 0 SN7425 .35 0 SN7465 .39 0 SN74105 .95 0 SN74158 1.45 0 SN74199 2 .45 The most amazing audio offer for the hi- fi-ers. PA men, 0 SN7426 .31 0 SN7470 .49 D SN74106 .95 D SN74160 1.85 D SN74200 7.so and an ideal unit for the family den, or any room in the 0 SN7427 .35 0 SN7471 .ss house office, etc. Comes complete with hookup, es. cutch~o n, and knobs. 5 separate controls: LOUDNESS. Terms: add po,.;tage Rated: net :~ 0 BALANCE. TREBLE, BASS, circuits switch for PHONO, INTEGRATED CIRCUIT Phone Orders: Wakefield, Mass. (617) 246-3829 TUNER, TAPE. ~UKE , AUX. 3 switches for SCRATCH SOCKETS Retail: 1 6pl8 Del Carmine St.. Wakefield, Mass. FILTER, RUMBLE FILTER, and POWER "ON-OFF" with ( off Water S treet) C.O.D. 'S MAY BE PHONED built-in lite. 4-outout transistors, each 30 watts. Sepa­ r ate accessor:r mounting panel fo r ·1 speake1· nttach­ B:::::~: ~I~ M~~~tI· g~ D 20c CATALOG on Fiber Optics, 1JCs', .Semi's, Parts DIP ...... SG ment, mike and musical instrument jack, tape, t u ner~ 016·Pln, MINIMUM ORDER-- $4.00 and power jacks. 6- ft, cord set for 115VAC, 60 cycles. O TO·S, 8 or 10·Pins .•29 Buy Any 3 0 8 ·Pins (MIRI DIP) . . 39 Measures onl:r l :~ x 7 x 3". Wt. a lbs. With attractive Take 10% O 14-Pin, Wire Wrap G&c multi·color escutcheon. Made by leading US make1·. Discount! O PDLV'PAKS 16-Pfn, Wire Wrap : : .' 89c P . O . BOX . 942£. LYNNFIELD, MASS. 01940 • 20-20,000 Cycles Resp e 4-Channel Spkr. Systems!

JANUARY 1975 CIRCLE NO. 30 ON READER SERVICE CARD 105 DIGITAL MODEM SYSTEM S, $45.00, IC 's under 10 cents USE your transistor radto as a sensitive direction finder. each , miscellaneous computer equipment. Send SASE for PLANS AND KITS Great fo r emergencies. Complete plans. Guaranteed free flier, MNH-Applied Electronics, P.O. Box 1208, Land­ results. $1.00. RADIO COMPASS, Dept. B, Box 606, Webb over, MD 20785. ATTENTION AUDI O FREAKS!! . . . Audio Processing Cir­ City, Missouri 64870. RESISTORS 1/2, 1 /4 watt 2 cents minimum $2.00. 5314 cuits ... designs, kits, units. Labo ratory tested designs fo r TESLA COIL-40" SPARKS! Plans $7.50. Information 75 clock chip $5. 00, SLA-1 readouts $1.00. tectronix, Box 42, hobbyist through professional use-limiters. compresso rs , cents. Huntington Electronics, Box 2009-P , Huntington, Madison Heights, MICH 48071 . equalizers, phasers , mixers and more! Send now-$1.00 Conn . 06484 . (refundable) for complete catalog-CI RCl.JIT RESEARCH FREE-Catalog of Electronic Surplus Component LABS, 3920 E. Indian School, Phoenix, AZ 85018. Bargains. 10 cent stamp to TRl-TEK, Bo x 14206, Phoen ix, HIGH FIDELITY AZ 85063. DIAMOND NEEDLES and Stereo Cartridges at Discount CONSTRUCTION PLANS. New projects every month . Send prices for Shure, Pickering, Stanton, Empire, Grado and for complimentary copy. El ectronic Projects Newsletter, ADC. Send for free catalog. LYLE CARTRIDGES, Dept. P. Box 1026S, Fremont, Calif. 94538. Box 69, Kensington Station, Brooklyn, New York 11218. .CATALOGUEE~t~~~~ICS SAVE 50%. Build your own speaker systems featuring Nor­ CIRCUIT board service. Circuit boards made from your $1.00 + . elco, Eminence and CTS. Famous brands from world's lar­ layouts. Sen d for information . Pri nted Circuits, 22 Maple (refundab le on 1st purchase) Avenue . Lackawanna, New Yo rk 14218. KITS gest speaker factories at lowest wholesale prices. Write for featuring free catalog of speakers and electronic accessories. FREE BARG AIN CATALOG . Transistors, LED 's, Readouts, •Sf NC LA I A h i·fi modules and ca lc ulator McGee Radio Company, 1901 McGee Street, Kansas City, Micro-Miniature Parts, Un usual Electronic Components. kits. We wi ll i nclude the new 32-page Missouri 64108. Chaney's, Box 15431, Lakewood, Colorado 80215. Project 80 h i-fi module construction TELEPHONE OR OFFICE BUGGED??? ... Learn How To manual. 1 Protect Yourself. Details $1.00. SECURITY, Box 671, West­ LISTEN TO SPECTACULAR 4 CHANNEL SOUN0 • AMTRON electronic kits - over 100 types! E1pand your stereo to quadraphonic Hi -Fi. wood , New Jersey 07675. •Speaker k its and components Build the VISTA Full logic " SQ" Decoder. KEYBOARD, ASCII , $35.00; UART, $10.00, 2102 memories, Amer ican enquiries welcome ' Latest CBS licensed circuitry using 3 IC's to provide Full lo&ic and Wawe $10.00, 1101 A, $2.20, some microprocessor parts. CMOS Matching. RCA CD4017, $1.00. Beckman , 1618 James, Syracuse, N.Y. GUJDBTDnE-.\~rELECTRDnlCS E1tlusivel1 ours. Kit SQ·! $37.50. Shipped prepaid In USA & CANADA. 13203. Send for information. ~~~~~~~~~~~~~~~~~- 1736AV ENUE RD., TORONTO, ONT. VIDE0 1/4" Tape System-Portable. AKAi VT-100 $700.00. PHOTOLUME CORPORATION ZELL, Box 17017, Euclid, Ohio 44117. M5M 3Y7 . DEPT. PE · I 118 East 28th Street New York fil Y 10016

FREE CATALOG . 200+ unique electronic projects. Bio­ SHOTGLASS. As seen in Esquire. Glasscone Column NEW: ROTARY CIRCUIT LOCALIZER feedback, acupuncture, more! Cimarron Labs, 4183A Speaker. $129.50 each. F.O.B. Moneyback Guarantee. Visual Ald OiskS-turning re­ Springfield St., Burton , Michigan 48509. TECHYONS , Box 1012, Roselle, Illinois 60172. veals visual electrical effects and explanations simultaneously of capacitor inductor and res is­ complete calculator MOVIE FILMS tor components. $4.SOaSet-CondensedElecl.Theor, 8MM-SUPER 8-16MM MOVIES! Biggest Selection! Lowest Peri Cale Prices! Free Catalog! Cinema Eight. Box PE. Chester, Box 523, San Francisco, CA 94101 KITS Connecticut 06412. ALL PARTS. INSTRUCTIONS INCLUDED SIMPLIFIED PC BOARO CONSTRUCTION ELECTRICAL SUPPLIES & EQUIPMENT ALARM CLOCK CHIP MM5316, $6.50! HP5082-7730 7 seg 12 DIGIT CAPACITY . 5x3x1 SIZE LED, $1 .50! 60 cents postage. BDJ Electronics, Tappan . 4 5 6 SELECTABLE DECIMAL. BATIERY OR AC PLATING Equipment, Portable Platers, Supplies and New York 10983. " Know-How." Build your own tanks fo r nickel, chrome . 2 3 8 d igit display - $19.95. 9 digit ­ $22.95. NiCad power pack - $3.96 etc . Easy-to-install PVC liners. Rectifier components-all WANTED 0 AC adapter/recharger - $2.95 sizes. Schematics , parts lists, formu las, operating Manual only - $2.00 (deductable instructions for all plating . Guaranteed to save you 25%­ fr om Kit). Shipping - $1.50 WIZARD ELECT.RONICS, Dept PE·l 75% . Some good units for sale. Write for details. Platers QUICKSILVER, Platinum , Silver, Go ld, Ores Analyzed. Service Company. 1511-PE Esperanza, Los Angeles, Calif. Santa Cla1a Free Circular. Mercury Terminal, Norwood, Mass. 02062 . P.O. Box 161 Agnew California 95054 90023. BURROUGHS PANAPLEX ~~? Let us know 8 weeks in advance so that you won't m miss a single issue of POPULAR ELECTRONICS. BURROUGHS PANAPLEX II 12 digit display BR13251 Attach old label where indicated and print new is a multi-digit, segmented, thin panel display in a common address in space provided. Also include your mail· envelope. Any or all digits may be used, along with periods ing label whenever you write concerning your sub­ and commas. The characters are 0.25", and are ideal for scription. It helps us serve you promptly. any device requiring multiple digits, clocks, counters, cal­ Write to: P.O. Box 2774, Boulder, CO 80302, giv­ cu lators etc. Compatible with DTL, TTL & CMOS circuit­ ing the following information: ry and chips. Display is neon glow discharge, orange color. D Change address only. We provide many pages of data & applications. Cost is less O Extend subscription. O Enter new subscription. 3 tha 1.00 per digit. 1"x3 /4" for 12 digit display. D 1 year $6.98 STOCK NO.F220 11.95 ea, 2/21 .00 O Payment enclosed (1 extra BONUS issue) D Bill me later 12 VOLT DC SIREN :c;AFFIX LABEL 3 0 r . ~-,. , Ol ~ Hard to find 12 volt DC SI REN .ct ..,.I ideal for alarm systems or any 12 volt auto. 5 ~I STK. No. F5219 11.95 2/20.00 ~... "MI 9 0 I Heat sink assembly of 2 2N4904 PNP c 87 watt power transistor. Other tran­ ·E- 0. I sistor is compIimentary to above. Specs ... are same as 2N3055 except Bveco is •0 40 volts. All transistors mounted i n I . • 0 sockets. Distributor price of transistors 0. • is 3.35 ea. E xtra NPN xistors availab le I 0. for .75 ea. 'ii NO . F9034 assembly 3.50 3 / 9 .00 ... I .!! 0 Ml.NIMUM ORDER $5 .00 . Include postage, excess refunded. New c I edition of our catalog now avai lable. I . ; E -0 . .., ~ Phone (617) 388-4705 ~ 0 ·;:; ~ Add'I postaee: $2 per year outside U:S., its poss. & Can. CIRCLE NO. 13 ON READER SERVICE CARD 106 POPULAR ELECTRONICS Waveform Generator Kit C-MOS Calculator _: ~~:~?.~~ 1-9 10 up XR205K Only $28.00 liMind OUANTIT)' $7.90 4000AE $ .55 .53 Here's a highly versatile lab 4001AE .54 .53 instr ument at a fraction of 9·Digit Display 4002AE .54 .53 the cost of conventional unit. 4004AE 5.90 5.90 Kit includes two XR205 IC's, $19.00 • 1/ 8" character height 4006AE 3.90 3.80 data & applications, PC board •compact, thin PC 4007AE .65 .60 (etched & drilled, ready for package 4008A E 3.60 3 .30 assembly) and detailed instruc­ I 4009AE .95 .94 tions. Pisital 401 OAE .95 .94 .160"dia. 4011AE .54 .53 FM Stereo Demodulotor watch 4012AE .54 .53 216 Red XR1310 $3.90 ll>IUAL I.OW with llquid 4013AE 1. 15 1.05 crystal display. • •• 216 Yellow 4014AE 3 .70 3 .25 INJOISIE Beautiful . 216 Green ~ l~~SLA21:-~;~:":4~.:2~5~ Orange 4015AE 3.80 3.70 Audio Amps OP 114.fl.IAP reliable and S LA2 ± 1 Red 2.25 4016AE 1.15 1.05 accurate. S L A 12 ±1 Grn 2.25 4017A E 2.90 2.70 LM352 o 6-15V, 1.15W. an 1.60 LM331N: $149.00' plus S LA22 ±1 O rg 2.25 4018AE 3.20 3.05 LM354Ao 6-27V. 2.BOW. an 2.50 Vio = 6mV $2.50 for SLA3 Red 7.50 .200"cfia. 4019AE 1.30 1 .20 TAA611B12: 6·15V, 1.15W,8rl 1.60 lie = lOOOnA shipping and 4020AE 3.90 3.30 TAA621A12o 6 ·27V, 1.40W. an 2.00 lb:: 2000nA handling. 4021 A E 220 Red .25 3.80 3.60 T8A64181 1o 6-1aV.2.20W.4n 3.00 Noise = 1.5dB ~~~~2XAN52 Green==~ 2; . 50~g ~ 220 Yellow .30 4022AE 2 .75 .2.55 TBAaOOo 5-30V. 4.70W. an 2.20 $2.20 P1101 A $6.90 4023AE .54 .53 4 Optoisolator 220 G'een .30 4024AE 2.30 2.00 :;:~~~1g~;:1~~~~:,;~~':;'n n ~:~g P1101A1 8.50 4025AE .54 .50 TCAa30o 5-20V. 2.00W. 4n 2.20 P1402A 7.90 MCT2 1 45 L OW PROFILE 4026AE 9.80 7.10 TCA940o 6' 24V. 6.50W. an 4.40 P2102 15.00 226 Red $ .25 4027AE 1.35 1.22 P3101 5 .5 0 .A.. 226 Yellow .30 4028AE 2 .95 2.75 P3101A 5.50 °'ES'"' 226 Green ,30 4029AE 5.40 4.60 MMG5GON 5 .00 4030AE , .25 1.05 Power Transistors HYBRID MMG561N 5.00 4035AE 2.85 2 .80 DM8599N 5.00 4040AE 4.60 4.40 BU204 3A 1300V $4.14 ,o._\, AMPLIFIERS 93403 5.00 4041AE 3.30 3.20 BU205 3A 1500V 4 .95 Sl -1010G 10W 4042AE 2.95 2.85 BU206 3A 1700V 5.94 $ 6.90 Decoded Read/ 1300V 5.85 S1-1020G 20W 9.90 ii 4043AE 2.95 2.85 BU207 GA Write RAM ·=i~ ~ 'i~i·~rr~,: Sl-1030G 4044AE BU208 GA 1500V G.93 30W 18.70 2.95 2.85 Sl-1050G P1103 $G.20 LM100H $550 216-MV5024 4047AE 3.70 3.60 BU209 6A 1700V 8.G4 sow 25.90 4048AE 1.50 1.40 ~«~~«~~~~»~~»!'W«~~«~~~~~~~~~ t~~ g~~ ~ ~g 5053 - MV5053 4049AE 1.35 1.05 2N512B $3.00 4050AE 1.35 1.05 2N113G 1.50 PREMIUM QUALITY coMPoNENTs ~~~g~~ ~~g 4056AE 3 .50 3.46 2N 1483 1.20 Linear ICs 2N1534 1.00 We've been buying and selling top quality components for nearly L M 109K 6.30 4060AE 5 .20 4.90 LM114H 2N1540 1.10 ten years. Our annual volume exceeds $3 million. We handle LM200H 3.80 T0-5 $ 3 .00 4066AE 3.20 2.96 LM301 A T0-5 .90 4069AE .85 .75 2N1544 .90 only original parts, from the world's leading manufacture rs and t~~~:~ ~:bg 2N30 53 .35 LM301AM Mini-dip .75 L M301AN Dip 1.10 2N3055 .95 our custome~s include some of the largest and most quality- LM20SH 3_50 T0-5 .95 Schottky 2N3375 5 .50 conscious companies. LM209K 3.70 LM302H LM302N 2N3442 2.20 LM300H .90 Dip 1.40 T0-5 TTL 2N3730 1 .70 Now you can take advantage of our component LM300N 1.40 LM306H 2.80 LM307H T0-5 .90 2N3731 2.00 buying skills and power and select from a broad LM304H 1.40 SN74SOON $ .BO L M307M Mini-dip 2N3732 1.50 LM305H 1.10 .90 SN74S02N .80 range of advanced circuits. L M308H T0-5 2N3771 2 .20 LM305A H 1.40 1.20 SN74S03N .80 LM308AH 2N3772 2.30 LM305N 1.20 T0-5 5.00 LM310H T0-5 1.40 SN74S04N .80 2N3773 3.40 LM309H 1.75 LM311H SN74SOBN .80 2N3789 3.00 L M309K 1 .95 T0-5 1.70 SN74S10N .80 2N38G6 .95 L M318H TD-5 2.50 Teflon LM340-05K 2.60 LM555CM Mini-dip .9 0 SN74S11N .80 2N4347 1.60 ICsockets LM340-0GK .2.60 3 pin T0-5 LM709CH T 0-5 .45 SN74S20N .80 2N4348 2.00 Solder .55 LM340-08K 2.GO 2N4395 1.30 4 pin T0-5 .65 L M709CN Dip .45 SN74S30N .80 8 pin DIL .22 L M340-12K 2.60 LM7 10CH 2N4427 1.10 6 pin T0-5 .90 T0-5 .60 SN74S32N .80 14 pin DIL .26 1024 Bit LM340-15K 2.60 2N5109 2.10 8 pin T0-5 1.10 L M710CN Dip .75 16 pin OIL .29 LM340-18K 2.GO LM715CH T 0 -5 . 4 .30 SN74S40N .80 2N5322 .92 10 pin T0-5 1.40 . rt-Channel 24pinDIL .75 LM340-24K 2.60 L M725CH SN74S41N .80 2N5323 .70 26028 $21.00 T0-5 5.00 28pinDIL 1.10 Wire Wrap LM723H 1.30 LM733CH T 0-5 1 .50 SN74S64N .80 2NG099 .80 RAM 2602-1 B 25.00 LM723D 3.90 36 pin OIL 1.70 LM733CN Dip 1.50 14pin DIL 7552CPE 21.00 SN74S74N 1.50 2N6101 .80 40 pin DIL 1.90 .40 LM723CH .80 16 pin OIL .45 7552-ICPE 25.00 LM741CH T0 -5 .45 SN74S85N 6.10 2N6103 .90 LM723CN .75 LM741CM Mini-dip .44 L 129 1.50 SN74S86N 2 .90 LM747CH T0-5 1.90 SN74S112N 2.50 L130 1.50 LM747CN D ip .9 0 L131 1.50 SN74S113N 1.50 7400N $ .1G 7400tt TTL 74150N $ 1 14 LOW 93LOO 1.50 LM748CN Dip .40 SN74S133N 1.00 7401N .23 74151N .75 93L01 1.60 SG4501 T 2.20 LM3046CN Dip .95 SG4501N 2.20 LM3054CN Dip 1.50 SN74S138N 4.50 7402N .22 7474N .38 74152N 2.25 POWERTn 93L08 3.20 1.80 SN74S139N 3.90 7403N .22 7475N $ .GS 741 53N 1. 12 93 L 09 74LOON $ .34 93L10 2.80 Ph ase Locked Loops SN74S140N 1.00 7404N .25 7476N .59 74154N 1.63 74L02N .34 93L11 4 .20 SN74S151 N 3.30 7405N .29 7480N .GG 74155N 1.49 1.80 LM567CM Mini-dip 2.10 74L03N .39 93L 12 DM8820N 4.00 SN74$153N 3.30 7406N .38 7481N 1.21 741 56N 1.49 1.70 74L04N .39 93L 14 DM8820AN 6.50 SN74S154N 3.40 7407N .48 7482N 1 .01 74157N 1. 19 93L 16 3 .20 Power Regulators 74L10N .34 3 .50 DM8830N 4 .50 IC SN74S 1 57N 2.70 7408N .24 7483N 1.01 74158N 1.54 93L 18 DM8831N 5.00 74L20N .39 1.50 LM335K : 5V, 600mA 2.40 SN74S158N 3.00 7409N .54 7484N 3.01 74160N 1 ,50 93L21 DM8832N 5.00 74L42N 1 .62 93L22 1.80 L M336K: 12V, SOOmA 2.90 SN74S160N 6.60 7410N .24 7485N 2.49 1.35 9GOO 1.30 74161N 74L47N 2.GO 93L24 2.80 LM337K : 15V, 450mA 2.90 SN74S161N 6.60 7411N .29 7486N .4 9 74162N 1.50 3.70 9601 1.30 74L51N .34 93L28 9602 2.00 SN74S174N 4.75 741 2N .5 1 7489N 2.99 74163N 1.50 93L34 4 .00 74L73N .74 9614 3 .00 SN74$175N 4 .00 7413N .78 7490N .75 74164N 1.89 93L38 4.20 74L 74N .89 9615 3.00 SN74S181N 11.50 7414N 2 .81 7491N 1.40 74165N 1.89 93L40 6.50 74L 90N 1.G2 961G 4.50 SN74S189N 5.10 741 6N .4G 7492N .84 741G6N 1.98 93L4 1 G.50 3.00 74L93N 1.74 3.00 9617 SN74S194N 3.30 7417N .G4 7493N .84 74170N 2.55 93LGO 3 .50 74L95N 1.62 93L66 2.70 9620 SN74$195N 4 .40 7420N ,19 7494N 1.29 74173N 1.79 962 1 3 .00 lnterd esign 1101: 0.1Hi:-2MHi:, SN74S251N 4.20 742 1 N .5 1 7495N .88 74174N 1.52 0-5V Output, va r. width , line or SN74S253N 4 .20 7423N .49 7496N .88 74175N 1.50 Model4440~ battery operation. $159.00. SN74S275N 3.20 7425N .39 7497N 2.50 74176N 1.69 A PORTABLE SN74S258N 3.70 7426N .29 74100N 1 .45 74177N 1.69 4\1\ DIGIT : , ·· e e SN74S260N .90 MULTIMETER . . ·. , . 7427N .35 74105N .54 74180N 2.49 FOR $299. - · ••,.,•••.,., • ilecirculoting 512 ilit SN74$280N 5.70 7428N .51 74107N .48 74181N 3.85 Dynamic Shift Register SN74289N 5.00 A lOMHZ 2524v 7430N .22 74108N .91 74182N 1.19 COUNTER OPTION 93510 6.80 1 - 24: $4.00 I 25 up: $3.90 7432N .28 74109N .9 1 74184N 2.89 ">FOR $50. 93$ 16 6.80 7433N .G1 74110N .71 74185N 2.29 93$21 3.50 7437N .44 741 1 1N .9 1 74190N 2.8,9 MOO 93$22 3.20 743BN .44 74114N .9 1 74191N 2 .89 lnterface Modules Shift 93$48 3.70 7439N 1.01 74115N .91 74192N 1.49 CY1010 i nstr. Amp.. Bipolar Input 29.00 SERIES 7440N ,19 74118N 1.50 . 74193N 1.39 CY1011A Instr. Amp., Bipolar Input 49.00 Registers 9300PC $1.00 CY1020 Instr. AmP.• F E T Input 34.00 7441 AN 1.16 74119N .81 74194N 1.35 1402A $ 7 .90 9301 PC 1.20 CY102 1 Instr, Amp., F ET Input 49.00 1403A G.00 9304PC 1.50 HIGH 7442N .98 74121N .54 741 95N .99 CY102 1A Instr. Amp., FET Input 59.00 1404A 6 .00 930GPC G.90 .98 SPEED TTL 7445N 74122N .89 74196N 2.39 CY2018 DAC, 8 Bit, 2 Quad Multiplying 99. 00 1405A 4.50 93.0BPC 2.50 74HOON .34 7447N 1.50 74123N .95 74197N 2 .39 CY2137 DAC, 10 Bit, Low Drift 39.00 1406 6.00 930 9PC 2.50 74H01 N .49 7448N 1.29 74125N 1.39 74198N 2.59 CY2218 DAC, 12 Bit, 2 Quad Multiplying 149.00 1407 6.00 9310PC 1.50 74H04N .36 7450N .23 74126N 1.39 741 99N 4.48 CY223G D AC, 12 Bit, Fast Settl ing, 150G 3.00 9311PC 2.50 74H05N .38 7451N .28 74128N 1.21 74200N 5.05 Low Drift 89.00 1 507 3.00 9312PC 1.20 74H08N .44 7453N .25 74132N 2.05 74122N 1.75 CY2237 DAC, 1 2 Bit. L ow Drift 69.00 2505K 4 .00 9314PC 1.30 CY2735 DAC, 4 Digit BCD, Low Cost 79.00 74H10N .44 7454N .2G 74136N .9 1 74251 N 1.75 2512K 5 .50 931GPC 1.50 74H11N .44 CY2737 DAC, 4 Digit BCD, Low Drift 1 39.00 2524V 4.00 9318PC 2.30 74GON .24 74141N 1.89 74278N 2 95 74H15N .38 CY3035 ADC, 8 Bit, Sect. Counting, 2525V 5.50 9321 PC 1.20 7470N .30 74H20N .39 74145N 1.79 74293N .92 L ow Cost 89.00 2533V 10.90 9322PC 1.30 74H40N .36 74721\J .39 74147N 2.95 74293N .92 CY3635 A D C, 3 Digit BCD, Sect. Count, 2807 4.00 9324PC 2.00 74H74N .G9 7473N .4G 74148N 3.55 74298N 2.55 L ow Cost 11 9 . 00 2808 5.50 9328PC 2.50 28 14DC 8.20 9334PC 2.95 MM5055N 5.00 9338PC 3 ,30 I-Amp RectHiers MINIMUM 10 100 1000 MM5056H . 5.00 9340PC 5.00 0 MM5057N 5.00 9341PC 4 . 10 1N4001 $ 1.00 7.00 G0.00 MM5058N 10.9 0 9342PC 1. 15 1N4002 1.10 8 .00 70.00 TMS31 14J 9 .50 9360PC 1.75 1N4003 1.20 9.00 80.00 1N4004 1.30 10.00 90.00 TMS3133NC 10.90 9366PC 1.75 1 N4005 1.40 11.00 100.00 TWO PHASE MOS CLOCK DRIVER 1N4006 1.50 12.00 11 0.00 1 N4007 1.GO 13.00 120.00 @iNCRONi COiii MH0026CN $5.50 P.O. Box 2208P, Culver City, CA. 90230 SPECI Fl CATION :SHEEETS: $.25 ea. California residents add 6% sales tax.

JANUARY 1975 107 1930-1962 Radio Programs . Reels, $1.00 Hour! Cassettes, TUBES $2.00 Hour! . .. Mammoth Catalog, $1.25. AM Treasures, PERSONALS Box 192F, Babylon, N.Y. 11702. MAKE FRIENDS WORLDWIDE through international RADIO & T.V. Tubes-36 cents each. Send for free correspondence. Illustrated brochure free. Hermes, Berlin Catalog. Cornell, 4213 University, San Diego , Calif. 92105. 11, Box 110660/ZD, Germany. RECEIVING & INDUSTRIAL TUBES, TRANSISTORS. All l1iowP.cAt~b~§1!I!;J~!!,~.~~t,1cope plash( box . famous b1and cassenu. " likt new" 10 ·1/2" me tal or hbet&lns mis. en d for op en ml and casse lh discount catalo&. 1·9 IO·M JOO 1000 Brands - Biggest Discounts. Technicians. Hobbyists. assette labels ( ML1lt iples ot 10) .02 .015 .01 Experimenters - Request FREE Giant Catalog and SAVE! ore lco Cassette Cleaner .&5 .60 .55 .SO INVENTIONS WANTED ZALYTRON, 469 Jericho Turnpike , Mineola, N.Y. 11501. assefle Paper Maile1 Som .OJ .025 .022 .02 catch Camlle SC90HC. Buy 2. &el ONE FREE 2.72 2.55 2.44 2.39 CASH-ROYALTIES for patented , unpatented inventions. TUBES receiving, factory boxed, low prices, free price list. J0 -112" Fibera:lass Reels , Lrse d 50 .50 .40 .35 Global Marketing Service, 2354-P Telegraph , Oakland, Transleteronic , Inc ., 1306 40th Street, Brooklyn, N.Y. 10-112" Metal. NAB' Hole, Ustd 1.00 1.00 .90 .80 California 94612. lus Posta1e by Weia:hl and Zone Minimum Ordtr. $5.00 11216A, Telephone : 212-633-2600. SAXITONE TAPE SALES '~!s,;~~~~.- DR~.··i~· . INVENTORS: Protect yo ur ideas! Free •· Recommended TUBES " Oldies", latest. lists free . Steinmetz, 7519 Procedure ". Washington Inventors Service, 422T Maplewood , Hammond , Indiana 46324. Washington Building , Washington, D.C . 20005. TUBES 60% OFF LIST PRICE. McCord Electronics , Box FREE PAMPHLET: " Tips on Safeguarding Your Invention ." 276-T, Sylvania, Ohio 43560. GOVERNMENT SURPLUS Write: United States Inventors Service Company, 708..T Carry Building, Washington, D.C. 20005. GOVERNMENT Surplus . How and Where to Buy in Your FILE your own patent application. Complete information TAPE AND RECORDERS Area . Send $2.00. Surplus 30177-PE Headquarters Bldg. , Washington, D.C . 20014. and materials . Write: Inventor's Guide, 468-R, Goodspeed Road , Virginia Beach, Virginia 234_5_1.______RENT 4-Track open reel tapes-all major labels-3,000 MANUALS for Govt Surplus radios, test sets, scopes. List different -free brochure. Stereo-Parti, 55 St. James Drive, 50 cents (coin). Books, 7218 Roanne Drive, Washington , • Santa Rosa , Ca. 95401. D.C. 20021.

TRANSISTOR SPECIALS 74C 02 ...... $.55 2N256 PNP GE T0-3 ...... $ .50 74C 10 ...... $.60 2N404 PNP GE T0-5 ...... 4/$1.00 74C 157...... $2.15 2N1137B PNP GE T0-3 ...... $ .95 74C 165... . .$3.50 MINIATURE TRIM POTS 2Nl016A NPN Si T0-82 ... ..$.1.95 CD 4001 . . . . .$.55 5K, lOK, 25K, 50K, lOOK, 2N3904 NPN Si T0-92 ...... 4/$1.00 CD 4002...... $.65 MPS3393 NPN Si T0-92 .....4/$1.00 CD 4009 ...... $.80 •75 EA. 3 2.00 2N3906 PNP Si T0-92. . . .4/$1.00 CD 4010 ...... $.65 If you have an idea for a new product, or a way to MULTI-TURN TRIM POTS MPS Al3 NPN Si T0-92 .....3/$1.00 CD 4011...... $.55 SimilartoBourns3010style3/16" x %" x 2N3767 NPN Si T0-66 ...... $ .70 CD 4012 ...... $.55 make an old product better, contact us, "the idea 1Y4" 50, 100, 500, 2000, 5000, 10,000 2N2222 NPN Si T0-18 . ....5/$1.00 CD 4013... .$1.20 people." We'll develop your idea, introduce it to 2N3055 NPN Si T0-3 ..... , ...$ 1.00 industry, negotiate for cash sale or licensing. ohms. $1.50 3/$4.00 CD 4016. . ...$1.25 ea. 2N5296 NPN Si T0-220 . . ..$ .50 CD4019 ..... •• • ...... $1.35 Send for our FREE "Invention Kit." It has a PRINTED CIRCUIT BOARD 2N6109 PNP Si T0-220 . . ...$ .55 CD 4022 . . ..$2. 25 I special "Invention Record Form," an important 1 4W'x 6112'' single sided fiber 2N4898 PNP Si T0-66 ....$ .60 CD 4023 . . ..$.55 brochure, "Your Invention ­ Its Development, Pro- MJ2252 NPN Si T0-66 .. . $ .90 I glass board, 1/16" thick, un­ CD 4025 . $. 55 tection & Marketin1," and a Directory of 500 2N3638 PNP Si T0-5 ...... 5/$1.00 CD 4027 ...... $1.35 etched .50 ea. 5 2.20 2N2218A NPN Si T0-5 ...... 4/$1.00 I Corporations Seekin1 New Products. You'll learn CD 4030 , , . . .$.65 • how ideas become a rea I ity! LIGHT ACTIVATED SCR's, CAPACITORS CD 4050...... $1.35 I TO-l{l 200V lA . $Pl> . 6V 30 UF TANT. 5/$1 Full Wave Bridges RAYMOND LEE ORGANIZATION NIXIE TUBES 20V 4.7U F TANT. 5/$1 MAN-1. RED OR YELLOW PRV 2A 6A 25A 12V lOUF ELECT. 5/$1 LEO READOUT ....S2.50 230 Park Avenue, New York, N.Y. 10017 I Similar to Raytheon 8650 200 .95 1.25 4.00 tubes, with socket & data 50V IOOUF ELECT $.40 MAN·3 READOUTS $1. 75 ·400 1.15 l.50 5.00 I'd like to find out how t6 take action on my 25V 30UF ELECT 4/$1.00 MAN-4 READOUTS S2.00 600 1.35 1. 75 6.00 idea. Send Free " Invention Kit No.A.. 112" sheet 2.25 3 6.00 11031024 bit RAM ...... $4.7 FPA-711 - THESE PHOTO DIODE 5311-CLOCK CHIP 6 DIGIT BCD NEC 6003 2048 bit RAM ..$9. 50 HOLD COUNT, OUTPUT ==------;;,Pl""ea:::s::-eP"'r"'ln'"t ARRAYS ARE USED TO READ 1101 256 bit RAM ...... $1.75 ------1 SEVEN LEVEL TAPE 100 ma STROBE ...... $7. 75 8225 64 bit-write RAM $2. 75 5314-CLOCK CHIP 6 DIGIT HOLD SPACING...... , ... .$5.95 8223-PROGRAMMABLE COUNT, OUTPUT STROBE . ...$7 .75 ~ddre'5 TIS 73 N FET ...... $.50 ROM ...... $4.75 J · ~316-A. l.ARM CLOCK CHIP . .$8.50 City tale Zip 2N4891 UJT ...... $.50 MM5203-2048 BIT ERASABLE ER900 TRIGGER DIODES 4/$1.00 PROM ...... $23.95 2513-64 x 7x5 1 11 11 1 11 1 CHARACTER GEN ...... $9.95 lu W!ifli· .f#M!lf •·""11r' M·!li'Bi ·'H!li1ti!i!1· 2N6027 PROG. UJT ...... $.75 Conductive Elastometer low ITS 1233 DUAL FET ...... $1.95 profile calculator keyboard. A 2516-64 x 6x8 STATIC 23/4" x 31/4" x If2 " flex key. CHARACTER GEN ...... $9. 95 VERIPAX PC BOARD 19SK-6 keyboard having 0-9, • · INSTRUCTION This board is a 1/ 16" single SANKEN AUDIO POWER AMPS +, - , x ,+ ,~, K+Cbuttonswith Si 1010 Y 10 WATTS ...$ 6.40 LEARN ELECTRONIC ORGAN SERVICING at home all sided paper epoxy board, off, on switch. $6.00 4V2''x61/2" (standard veripax) , Si 1025 E 25 WATTS ...$17.95 makes including transistor. Experimental kit-trouble­ DRILLED and ETCHED which CT5005-12 DIGIT CALCULA· Si 1050 E 50 WATTS .. . $24.95 shooting. Accredited NHSC, Free Booklet. NILES BRYANT ~!~~~~.I~~~ E§1 5D~~ 1 fc!s4.Jii~ TOR CHIP ...... $7.95 LINEAR CIRCUITS SCHOOL, 3631 Stockton, Oept. A, Sacramento, Calif. ITL IC SERIES LM 309K 5V 1A REGULATOR ...... S1.65 95620. busses for power supply con­ 74LOO­ .30 7476­ .47 nections. Is also etched for 22 723 -40 +40V REGULATOR ...... S.58 LEARN WHILE ASLEEP, Hypnotize' Strange catalog free . pin connector $5.25 7400­ .18 7480- .65 30 1/748 -Hi Per. Op. Amp ...... $ .35 7401 - .18 7483­ 1.10 LM 320 -5 or - 15V REGULATOR ...$1 .75 · Auto-suggestion , Box 24-ZD , Olympia, Washington 98501. FLV 100 VIS IBLE LED ...... $.50 7402­ .18 7485-1.30 LM 376 -V to 37V POS REG ...... $ .58 . DEGREE IN ELECTRONICS through correspondence. Free 7403- .18 7486­ .48 ME-4 IA LED ...... $.40 741A or 741C OP. AMP...... S.35 catalog. Grantham, 2000 Stoner Avenue, Los Angeles, MCD·2 OPTO-ISOL...... $.90 7404- .22 7489-2.75 709C OPER AMP ...... S.29 GREEN GAP OSL-16 LED . .$. 60 Z405­ .22 7490- .75 340T-5, 12, 15, 18 , 24V California 90025. RED GAP OSL-3 LED ...... $.40 7406- .37 7491-1.30 POS . REG . T0-220 ...... $1 .75 INTENSIVE 5 week course for Broadcast Engineers . F.C .C. 7407- .37 7492­ .75 14 PIN DIP SOCKETS . S.40 101 DPER. AMP., HI PERFORM ...... S.75 First Class license. Radio Engineering Incorporated, 61 N. 16 PIN DIP SOCKETS ....$.50 7408- .24 7493- .75 LM 308 OPER . AMP., LOW POWER .$1.05 7410­ .18 7495­ .99 747-0UAL 741...... $.75 Pineapple Ave., Sarasota, Florida 33577. 10 WATI ZENERS 74 11 - .30 7496- .95 536-FET INPUT OPER. AMP . .$2.60 SHORTCUTS To Success! Highly Effective, Profitable 3.9 , 4.7 OR 5.6 V ...... $.75 EA 7412­ .45 8220­ 1.50 537-PRECISION OP. AMP ...... S2.60 Short Courses (75 Choices). Study At Home . Diploma .4 WATT ZEN ERS 7413­ .75 74107­ .50 LM 3900-QUAO OP. AMP...... $.58 3.9 5.6. 6.8 OR 12 V. 7416­ .37 74121­ .60 LM 324-QUAD 741 ...... S2.20 Awarded. Our 29th Year. Free Literture . CIEE-D, Box 7417- .37 74123-1.00 560-PHASE LOCK LOOP ...... S2.60 20345, Jackson , Miss. 39209. 7420­ .18 74125-1.40 561-PHASE LOCK LOOP ...... S2.60 7426­ .30 74126-1.40 565-PHASE LOCK LO OP ...... S2.60 7427- .33 74150­ 1.15 567-TONE DECODER ...... S2.95 7430­ .18 74151- .95 703-RF-IF AMP ...... $.55 7432- .30 74153-1.10 LM 370-AGC SQUELCH AMP. . .$1.15 7437­ .44 74154-1.65 7438- .37 74 157­ 1.25 n~JJAt o/ ~~PTIMER •• .••• •• J~~ 7440­ .21 74163-1.60 1456 OPER . AMP...... $.95 7441-1.05 74164-2.05 LM 380-2W AUDIO AMP ...... $1.45 7442­ 1.00 74165­ 2.05 LM 377­ 2W STEAD AU DIO AMP . ...$2.60 REGULATED MODULAR 7445-1.10 74173­ 1.80 LM 381-STEREO PREAMP ...... SJ .75 POWER SUPPLIES 7446­ 1.15 74177-1.80 LM 382-DUAL AUDIO PREAMP . . . .$1.75 +-15VDCAT100ma, 115VAC 7447-1.15 74181-3.60 LM 311-HI PER . COMPARATOR . .. . .S.95 INPUT ...... $19.95 7448­ 1.20 74192-1.50 LM 319-0UAL HI SPEED COMP . $1 .25 5VDC AT lA, 115VAC 7450­ .18 74193-1.45 LM 339­ QUAD COMPARATOR ...S1.65 DEGREE Program in Electronics Engineering . 7472­ .40 74195-1.00 ...... 19.95 7473­ .43 75324-1.75 TRIACS SCR'S Yearl Free literature . Cook's Institute, Dept. 13, Box 20345, IN4148 ...... 14/$1.00 7474­ .43 75491­ 1.10 Jackson, Miss. 39209. 7475­ .75 Terms , FOB Cambridge Mass. LOGIC MICRO / MINI­ Send check or Money Order. Include 8038C IC VOLTAGE COMPUTER NEWS Postage. Minimum Order $3.00 TROLLED OSCILLATOR. Send 20c for our catalo11 featuring Transistors and Rectifiers; LOGIC NEWSLETTER© SAMPLE COPY$ I .00 LOGIC NEWSLETTER POB 2 5 2 WALDWICK, N.J. 07463 CIRCLE NO. 33 ON READER SERVICE CARD 108 POPULAR ELECTRONICS Altaj Electronic Bargains PRICES SLASHED! WE WANT YOUR BUSINESS. SATISFACTION GUARANTEED ON EVERY ITEM

MM5314 NATIONAL CLOCK CHIP RCA STYLE C-MOS MfNI CORE MEMORY SPECIAL The most popular clock chip around . We CD4001·39t CD4012-44¢ Mfg. by DATARAM. Stores 180 words of made a huge special purchase of factory CD4G02-39t CD4013-89¢ 18 bits each . With sense amps and fresh, prime units. Lowest price in USA . CD4009·75t CD4017-1.95 associated drive circuits. A complete 24 Pin DIP . 4 or 6 Digits. With Specs. CD4011-39ij; memory system . We include 50 pages of $3.94 EACH (3 For $10) data and schematics. Data only $2.50 Brand New. Special $24.95 DIGITAL ALARM CLOCK IC LM309K The newest and easiest to use alarm chip T0-3 Case, 1 AMP 5 VDC on the market today. Features: Voltage Regulator. Brand New ~ 1. Single supply voltage. By National 954 '"':-..:.:~ ~ 2. LED lot>o•lty ooot

JANUARY 1975 CIRCLE NO. 3 ON READER SERVICE CARD . 109 r ~ Quality ~ SCORE high on F.C.C. Exams . . . Over 300 questions and Electronic Components answers. Covers 3rd , 2nd , 1st and even Radar. Third and TREASURE FINDERS 51'1CW. 5AYINGS DISCOUNT ON LINlll AND DIGITAL INTEGRATED CllCUln Second Test, $14.50: First Class Test, $15.00. All tests , DN.ott •~ frOlll 1M 1otol of yo.ur LC. order If it ..cett11 S25.00 boitd co i.ing~ let pricn, H,, f,,.-S50.00fl'l!IOl'l,10,.forS100.00ormor1.Additiofiallor99qunn!llydiK01.01!$ctfw.d. $26.50. R.E.1., Inc., Box 806, Sarasota, Fla. 33577. FREE FACT-FILLED CATALOG! World's largest se lection! Metal detectors starting at $79.50. Two year guarantee! DIGITAL INTEGRATED CIRCUITS FCC LI CENSE through tape recorded lessons. Also Radar Three factories, U.S.-Canada. 1,200 dealers - Service 7400N .. 25.5c 7437N .. 42.0c 7480N .. 70.5c 741 54N . $2.22 Endorsement. Radio License Train ing, 10600 Duncan. Centers nationwide . Finest instruments at any price! 7401N .. 25.5c 7438N .. 42.0c 7482N . . 99.0c 7415SN . $1.17 Manhattan Beach . Calif.. 90266. 7402N .. 25.Sc 7440N .. 25.Sc 7483N. . Sl.17 74156N. Sl.14 Bu dget Terms. Dealer inquiries invited. Write: White's 7403N .. 25.Sc 7441N . . Sl.40 7485N. , $1.40 74157N . $1.11 FCC LICENSE. elect;onics design. satellite communica­ Electronics. Inc. Dept. PD50, 1011 Pleasant Valley Ro ad, 7404N . . 30.0c 7442N .. 90.0c 7486N . . 45.0c 74158N. Sl .53 tions. through correspondence. Free catalog . Genn Tech. Sweet Horne, Oregon 97386. 740SN .. 30.0c 744SN.. Sl.49 7489N . . $4.47 74160N . $1.50 5540 Hollywood Bv ., Los Angeles, CA 90028. TREASURE FINDER locates buried gold, silver, coins, 7406N .. 48.0c 7446N.. Sl.14 7490N • . 66.0c 74161N . $1.50 SELF-STUDY CB RADIO REP AIR COURSE. THERE 'S 7407N .. 48.0c 7447N.. Sl.11 7491N .. $1.05 74162N. $1.50 treasures. 6 powerful models. Instant financing available. MONEY TO BE MADE REPAIRING CB RADIOS. Thi s easy­ 7408N . . 28, Sc 7448N .. Sl.22 7492N .. 66.0c 74163N . St.SO Write or call for free catalog. Ph one (713) 682-2728 day or 7409N .. 28.5c 7450N .• 25.Sc 7493N .. 66.0c 74164N . Sl .58 to-learn course can prepare you for a career in electronics night. Dealer inquiries invited . Relco , Dept. AA20, Box 7410N .. 25.Sc 7451N .. 25.Sc 7494N .. Sl.10 7416SN . $2.45 enabling you to earn as much as $16.00 an hour in yo ur 10839, Houston, Texas 77018. 7411N .. 25.Sc 7453N .. 25.Sc 749SN .. Sl. 14 74166N . $2.00 spare time . For more information write : CS Rad io Repair 7413N .. 60.0c 7454N . . 25.Sc 7496N .. $1.14 74175N . Sl.00 Course, Dept. PE-0175, 531 N. Ann Arbor. Oklahoma City, 7416N .. 46.5c 7459N . . 28.5c 741 07N. 45.0c 74180N. Sl.17 Okla. 73 127. REAL ESTATE 7417N .. 46.Sc 7460N .. 25.5c 74121N . 46.Sc 74181N. $3.42 i'418N . . 31.Sc 7470N . . 33.0c 74122N . 49.Sc 74182N . Sl.14 7420N .. 25.Sc 7472N .. 36.0c 74123N . $1.08 74192N. Sl.73 MUSICAL INSTRUMENTS NEW .. . BIG ... FREE ...SPRING CATALOG! Over 2,500 7421N.. 25 .5c 7473N .. 43.Sc 74141N. $1.10 74193N . $1 .73 top values in FARMS , R ANCHES, ACREAGES, 7423N .. 72.0c 7474N: . 43.Sc 74 150N . $1.53 74198N. $2.75 30% DISCOUNT name brand musical instruments. Free RE CREATIONAL PROPERTIES, BUSINESSES, TOWN and 7426N . . 33.0c 7475N . . 69.0c 74151N . Sl.17 74199N . $2.75 Catalog. Freeport Music, 455N, Route 110, Melville, N.Y. COUNTR Y HOM ES in 40 states coast to coast! Over 3,800 7430N . . 25.Sc 7476N .. 46.Sc 74153N. Sl. 17 11746. PH OTOS! UN ITED FARM AGENCY, 612-EP West 47th St., LINEAR INTEGRATED CIRCUITS WHOLESALE! Pro:e~sion al Guitars, PA Systems. Altec Kansas City, MO 64112. 555V MINIOIP TIMER ...... 82.5c 558V MINIDIP DUAL AMP ... 75 .0c Speakers, 240W RMS Amplifiers. Free Catalog , Carvin , 565A DIP PU ...... $3.38 567V MINIDIP DECODER. . ... $3.38 Escondido, Calif. 92028. 709V MINIDIP OP AMP ..... 36.0c 723A DIP VOLTAGE REG ..... 82.Sc 741V MINIDIP OP AMP .. . .. 50.0c 747A DIP DUAL AMP ...... 97.Sc 30% +DISCOUNT. Name Brand Musical Instruments. Free 748V MINIOIP OP AMP .•... 42.0c LM3900 DIP QUAD AMP••. .. 60.0c Catalog. Continental Music, Dept. H, P.O. Box 300 1, STATEMENT OF OWNERSHIP. MANAGEMENT AND L129 5 VOLT REG ...... Sl.80 l130 12 VOLT REG ..... ·.·. $1 .80 Garden City, New York 11 530. CIRCULATION (Act of August 12, 1970: Section 3685, Ll31 15 VOLT REG ...... Sl.80 Title 39, United States Code). 1. Title of Publication: Popu­ MINIATURE ALUMINUM ELECTROLYTIC CAPACITORS BUSINESS OPPORTUNITIES lar Electronics. 2. Date of filing: October I , 1974 . 3. Fre­ - AXIAL LIAD TYPE ­ quency of issue: Monthly. 4. Location of known office of - "4"C ..._ H"C Tci.r...c. ·10 pl.,. 50% 1...-t•r ,._.,. 4.7 UfD) ·10 11ko17$%14.7 utDor 1-) I MADE $40,000.00 Year by Mailorder! Helped others make 1 II 11111 I 10 100 ' I 10 100 publication: One Park Avenue, New York, New York IUFD!SOV•... 14t 12c lit 33Uffi/16V .. . 15t 12c Ile :mUFD/1 6V . . 35t 2Sc: 24t money! Free Proof. Torrey, Sox 318-NN , Ypsilanti , 2..2Uf0/50V ... 14t 12t Ile 33UfDJ'25V ... 17e 13c 12' UlUfD/25V .. 4.ct 3Sc 32c Michigan 48197. 10016. 5. Location of the Headquarters or General Business 3.3 ml/35V .. . 14< 12c Ile 47 Uf0/l6V .. . Uc 14': 13c 470 UF0/16V . . 37c 30c: Ve Offices of the publishers: One Park A venue. New York, u~- ~llifuGu- . . ~~~m-~~~ FREE CATALOGS. Repair air conditioning , refrigeration . 10 UFD/16V . .._. . 14': 12t llc 100 UFDJ16V. . 19c !Sc 14< 1000 UFD/16Y .. 49c 39c 3Sc New York 10016. 6. Names and addresses of publisher, IOUFD/2SV .... 14c 12c Ile 100UF0/2SV . . 24c: 18c 17e 100JUFD/25V .. 7Sc 60c S5c: Tools, supplies, fu ll instructions. Doolin, 2016 Canton , editor, and managi ng editor: Publisher, Edgar W. Hopper, 22Uf0!16V .. .. 14c J2c lie 220UF0/16V . . !4c 18c 17c 2200U FD/16V .. 75c 60t 5Sc 22UFD/2SV .. .. 1Sc l3c 12c 220UFD/2SV .. 3Sc 25c 24.:: Dallas , Texas 75201. One Park Avenue, New York, New York, 100 16; Editor, 1 AMP SILICON RECTIFIERS MAILORDER MILLIONAI RE helps beginners make $500 Arthur P. Salsberg, One Park Avenue, New York, New 1N4001 50 PIV 12/Sl 100/$6 HXl0/$48 1N4005 600 PIV 8/$1 1oom 1000/$7( weekly. Free report reveals secret plan! Executive (1Kl) , York, 10016: Manager Editor. John R. Riggs, O ne Park A v­ 1N4007 1000 PIV 6/Sl 100/$1 1 1000/$88 333 North Michigan , Ch icago 60601 . enue, New York, New York 10016. 7. Owner: Ziff-D avis SILICON SIGNAL & SWITCHING DIODE PI ANO TUNING LE ARNED QUICKLY AT HOME! Publishing Company, One Park Avenue, New York, N.Y. IN4148 (IN914 equiv.) 12/Sl 100/$7 lM/SSO SM/$220 Tremendous field ! Musical knowledge unnecessary. GI 10016; 1. William Ziff, One Park Avenue, New York, N.Y. MOLEX SOLDERCON IC TERMINALS approved. Information free. Empire School , Box 450327 , 10016; 2. Dirk S. Brady, Charles Housman, Jules I. Whit­ man, Trustees F/B/O Dirk Ziff et al. 16 Ervilla D rive, 100/$1 500/$4.20 1000/$8.20 5000/$38.20 50,000/$275 Miami 33145 . Larchmont, N .Y. 10538; 8. K nown bondholders , mort­ LED 7 SEGMENT DISPLAYS $200.00 DAILY In Your Mailbox' Your opportun ity to do gagees, and other security ho lders owning or holding I per­ DATALIT-704 . . $1.00 DATALIT-707 . . $1.50 what mai l-order exp&rts do. Free details. Associates, Box cent or more of total amount of bonds, mortgages or other IC SOCKETS 4 AMP SLIDE SWITCHES 136-J , Holland, Michigan 49423 . securities: None . 9. For optional completion by publishers 8 Pin DIP Solder 35c SPST ... 12c 10/$1 DPDT .... . 25c 10/$2 $178 .00 WEEKLY. Work one hour daily. Free brochure. mailing at the regular rates (Section 132.121, Postal Service 14 Pin DIP Solder 45c REED RELAY FAS, Box 13703-A, San Antonio TX, 78213. Manual). 39 U.S.C. 3626 provides in pertinent part: "No 16 Pin DIP Solder 50c 6 AMP CONTACT s VOLT/20MA COIL person who would have been entitled to mail matter under 24 Pin DIP Solder $1.25 S2.00 10/$15 100/1125 former section 4359 of this title shall mail such matter at the CITIZENS BAND rates provided under this subsection unless he files annually VOLTAGE REGULATORS ~ 25 v. DISC CAPS ~U}(t'M!~ with the Postal Service a written request for permiss ion to 1 $1.80 ea. ~ot .. s; 3 . ~ : ~°: mai l matter at such rates." L129 SV 600mA .022 . . . 6c 4c 3.Sc 2.75c DEALER-DISTRIBUTORS In accordance with the provisions of this statute, I hereby request permission to mail the publication named in Item l L130 12V 500mA .047 . . . 9c 6c 5.3c 4.25c Send this Ad to: L131 15V 450mA .1..... 12c 9c 7.Sc 6c at the reduced postage rates presentely authorized by 39 PAL ELECTRONICS CO. u.s.c. 3626. % & % WATI CARBON COMP. William L. Phillips, Assistant Treasurer RESISTORS P. 0 . Box 778 • Westminster, Ca. 92683 ~~~~~~·· ~ 11 . Actual no. 5 each of the 85 standard 10% values (2.2-22MJ Y, W Resistors ...... Average of copies (425 pcs.) Sorted by value $12/set 2-4 are $11/set S.9 are $10/set. HOW TO SELL BOOKS BY MAIL. FREE INFOrl MATION . no. copies of single McCord. Bo x 276-D, SYLVANIA. OHIO 43560. 5 each of the 70 standard 10% values (10-5.6M) V. W Resistors each issue issue (350 pcs.) Sorted by value $12/set 2-4 are $11/set S.9 are $10/set. OPPORTUN ITY PACl.O. Box 126 Thief River Fall1. MN 56701 ITIES. Report on jobs now open . Details FREE. Aviation I certify that the statements made by me above are correct Employment Information Service, Box 240, Northport, New and complete. CIRCLE NO. 38 ON READER SERVICE CARD York 11768. WILLIAM L. PHILLIPS, Assistant Treasurer 110 POPULAR ELECTRONICS POPULAR ELECTRONICS

DATA SHEETS JANUARY 1975 WITH EVERY ITEM HOME ENTERTAINMENT FILMS FREE ~~fii~ ~~oWJ~~ER* • REDUCE YOUR PROJECT COSTS ~RTISERS INDEX ENJOY YEAR ROUND MOVIES IN YOUR HOME. Prices • . MONEY-BACK GUARANTEE continue to raise but we will deliver Columbia Pictures like • 24-HOUR SHIPMENT '74 Super Bowl, '74 Stanley Cup, '73 World Series and • ALL TESTED AND GUARANTEED Sugar Ray Robinson in Super B or Standard 8 Color for $16.~5 each, $7.50 In B&W until January 25, 1975. Castle • TRANSISTORS (NPN): 2N3S63 TYPE RF Amp & Osc to 1 GHz (pl.2N918} and Sportlite catalog available, 25 cents each. SPORT· 6/$1.0D 2N3S6S TYPE Gen. Purpose High Gain !T0·92/1D6 6/$1.0D LITE, Dept. PE-1, Box 24-500, Speedway, Indiana 46224. IEJIER PAGE 2N3S67 TYPE High·Current Amplifier/Sw SOD mA 4/$1.0D SBlllCE NO. ADVERTISER NUMBER 2N3866 TYPE RF Pwr Amp 1·2 W@ 1DD·6DD MHz $1.50 MAGAZINES AND BOOKS 2N39D3 TYPE GP Amp & Sw to 100 mA and 30 MHz 6/$1.DD 2N3904 TYPE GP Amp & Sw to 100 mA (T0·92/1D6} 5/$1.DD 2N3919 TYPE RF Pwr Amp J.S W@ 3·30 MHz $3.DO Adva Electronics ...... • . . • ....111 2N4274 TYPE Ultra-High Speed Switch 12 ns 4/$1.DD FREE catalog aviation /electronic/space Allied Electronics ...... , •.. . .. •..•. .• • ...... 91 books. Aero MPS6SIS TYPE High ·Gain Amplifier hFE 2SO 3/$1.0D Publishers, 329PE Aviation Road, Fallbrook, California AS$ort. NPN GP TYPES, 2N3S6S, 2N3641 , etc. (lS} $2.0D 2 Allison Automotive ... . •...... • ...... •...... 6 92028. 2N4249 TYPE IPNP} low-Noise Amp 1µA to SD mA 4/$1 .DD Altai Electronics ...... • . . • . . • ..•.. • .. . .109 FREE book prophet Elijah coming before Christ. Wonderful • FET's: bible evidence. Megiddo Mission, Dept. 64, 481 Thurston Ancrona Corporation ...... 107 N·CHANNEL (LOW·NOISEI: Rd., Rochester, N.Y. 14619. 6 Audio-Technica U.S.. Inc...... • ...... 25 2N4091 TYPE RF Amp & Switch IT0·18/1D6} 3/Sl.DO BOOKS-thousands titles, bargains. Catalog Free . 2N4416 TYPE RF Amplifier to 4SD MHz IT0·72} 2/$1.DD Cassiano , 92-27 New York Blvd .. Jamaica, New York 2NS486 TYPE RF Amp to 4SD MHz (plastic 2N4416} 3/Sl.DD B&K Products of Dynascan ...... 2 11433. E1DD TYPE Low·Cost Audio Amplifier 4/$1.0D Bell & Howell Schools ...... 74, 75, 76, 77 ITE4868 TYPE Ultra· Low Noise Audio Amp. 2/$1.0D , TIS74 TYPE High·Speed Switch 4Dfl 3/$1 .00 AS$ort. RF & GP FET's, 2NS163, 2NS486, etc. (8) $2.0D CREI Capitol Radio Engineering CRAFT AUDIO P·CHANNEL: Readers of the 2N436D TYPE Gen. Purpose Amp & Sw ITO· I 06) 3/Sl .DD Institute ...... 46, 47, 48, 49 isn't a lost art. are CUS· E17S TYPE High·speed Switch 125fl IT0·1D6} 3/$1.DO Cleveland Institute of Audio Amateur magazine Electronics, Inc...... 84, 85, 86, 87 tomizing and scratch building their JANUARY SPECIALS: equipment with gusto and great re- 2N3638 TYPE PNP TRANSISTOR GP Amp & Switch S/$1 .DD 10 Clifford's Hifi 1'1tlolesalers ...... 100 2NS163 TYPE N-CHANNEL FET GP Amp & Switch 4/$1 .DO II Continental Specialties Corp...... • • .. • ...... IOI suits. Free prospectus tells all. 741 Freq. Compensated Op Amp (OIP/TO·S/MINl·OIP} 3/$1 .DD Box JOP, Swarthmore PA 19081 1N914 or 1N4148 TYPE GP DIOOE 100 V/10 mA 1S/S1 .DD MM5316 Digital Alarm Clock·Snooze/Alarmmmer 13 Delta Electronics Co.....•...... •...... 106 Hrs, Mins, Secs - with Specs/Schematics $11.95 MMS736 6·0igit 4·Function Calculator 18 PIN DIP $ 3.9S 12 Delta Products, Inc...... •..•. . • ...... 17 RECORDS 38 Digi-Key Corporation . .... • ...... 110 • LINEAR IC's: Dixie Hifi Wholesalers ...... • . ....102 308 Micro·Power Op Amp ITO·S/MINl·DIP} Sl.00 OLDIES. 45rpm. Free Catalog. Corny's Record Shop , Box 3D9K Voltage Regulator S V @ 1 A IT0·3} Sl.50 324 lluad 741 Op Amp, Compensated (OIP} Sl.90 166TA, Mason, Ohio 45040. 14 EIGO ...... 83 380 2·S Watt Audio Amplifier 34 dB (DIP} Sl.29 555X Timer 1 µs·l hr, Oif. pinout from 555 (DIP) s .BS 15 Edmund Scientific Co...... 112 RUBBER STAMPS 709 Popular Op Amp IDIP/T0·5} $ .29 8 Exact Electroncis ...... 13 723 Voltage Regulator 3-30 V@ 1-250mA (OIP/TO ·SI s .58 739 Dual Low·Noise Audio Preamp/Op Amp (DIP} S1.DD 1458 Oual 741 Op Amp (MINl·OIP} s .65 RUBBER address stamps. Free catalog . 45 type styles. 16 GTE Sylvania ...... : .. ...• ... .28, 29, 30, 31 2556 Dual 5SS 1imer 1 µsec to 1 hour (DIP} $1.55 Jackson 's, Box 443G, Franklin Park , Ill. 60131 . 17 Great American Sound Co., Inc...... 101 MADE-TO..ORDER STAMPS. Low Prices. Free Catalog . Al · • DIODES: legheny, Box 14A, East McKeesport, PA 15035. 1N3600 TYPE Hi-Speed Sw 75 V/200 mA 6/$1.00 1N3893 TYPE RECTIFIER Stud Mount 400 V/12 A 2/$1.DD Heath Company . . . •. .. • ...... 14, 15 1N4608 TYPE GP & Sw 80 V/400 mA 6/$1.00 1N749 ZENER 4.3 Volt 1±10%) 400 mW 4/$1.00 PLASTICS 1N753 ZENER 6.2 Volt (±10%) 400 mW 4/$1 .DD 18 Illinois Audio ...... 102 1N755 ZENER 7.5 Volt (±10%) 400 mW 4/$1.00 International Correspondence School .. .. .18, 19, 20, 21 1N757 ZENER 9.1 Volt (±10%) 400 mW 4/S1.oo· 19 International Electronics Unlimited ... . , ...... 103 CASTOLITE pours like water, hardens like glass without 1N758 ZENER 1D Volt (±10%) 400 mW 4/$1.DD heat. Crystal clear, co tors. Embed flowers, seashells, IN965 ZENER 15 Volt (±1 0%) 400 mW 4/$1.00 37 International Hifi Distributors ...... •...... 93 1N968 ZENER 20 Volt (±10%) 400 mW 4/St.DO mementos, anything . Make fine gifts. Form flexible molds D5 VARACTOR 5·50 W Output@3D-25D MHz. 7·70 pF S5.DO over patterns of any shape, size. Reproduce your own F7 VAR ACTOR 1·3 W Output@ IDD·5DD MH z, 5·30 pF SI.DD 20 James Electronics ...... • ..• .. • ...... 104 designs in plastics, candlewax, metal, plaster, cement. •MAIL NOWI FREE DATA SHEETS supplied with every item from Send 50 cents for illustrated Manual. Profitable . this ad. FREE 739 or 749 Low·Noise Dual Op Amp included ($1.00 21 Lafayette Radio Electronics ...... • ...... 7 CASTOLITE, Dept. 75A/PE, Woodstock, 111. 60098. val ue) with every order of $10 or more, postmarked prior to 2/28/75. ORDER TODAY-All items subiect to prior sale and prices subil!ct to change without notice. REPAIRS AND SERVICES WRITE FOR FREE CATALOG offering hundreds of semiconductors 22 McGraw-Hill Book Company ...... • ...... 89 not listed here. Send 10d stamp. 23 Mcintosh Laboratory, Inc...... 99 TERMS : All orders must be prepaid. We pay postage. $1.00 handling 24 MITS, Inc...... • ...... 27 ELECTRONIC PROTOTYPE Models Built. Wire.Wrap, charge on orders under $10. Calif. residents add 6% sales tax. 25 Midwest Hifi Wholesalers ... . •..• ...... 100 Hand solder, P.C. Boards. Engineering consultation and drafting service available. ACE Technical Services, 23-13 Steinway St., Astoria, N.Y. 11105. Phone: (212) 728-8284. NRI Schools ...... 8, 9, 10, II ADVAELECTRONICS National Technical Schools ...... 64, 65, 66, 67 BOX 4181 R, WOODSIDE, CA 94062 HYPNOTISM Tel. (415) 851-0455 CIRCLE NO. 1 ON READER SERVICE CARD OEMorsco ...... • .. . ..•..• .. • ...... 99 SLEEP learning. Hypnotic method. 92% effective. Details 26 Olson Electronics ...... • ...... 93 free . ASR Foundation, Box 23429EG, Fort Lauderdale, Florida 33307. MAGNETS FREE Hypnotism. Self-Hypnosis. Sleep Learning Catalog! 27 Pace Communications Corp...... •...... 16 Drawer H400, Ruidoso, New Mexico 88345 . 28 Phase Linear Corporation ...... • ...... 23 AMAZING self-hypnosis record releases fantastic mental MAGNETS. All types. Specials-20 disc, or 10 bar, or 2 stick, 29 Pickering & Co...... THIRD COVER power. Instant results! Free trial. Write: Forum (AA1), 333 or 8 assorted magnets, $1.00. Magnets, Box 192-H, Randallstown, Maryland 21133. 30 Poly Paks ...... •..••. . • .. • ...... 105 North Michigan , Chicago 60601. REMAILS 31 Radio Shack ...... 5 STAMPS

32 SBE Linear Systems, Inc...... 63 WOW! 110 ALL DIFFERENT GERMANY 10 CENTS. Com­ LETTERS FORWARDED, Will Stamp and Zip. Max. 2, 50 cents. Malo, P.O . Box 1597, Boston, Mass. 02104. 33 Solid State Sales ...... 108 memoralives, Airmails , High Values, Big Catalog, bargain lists. Also, fine stamps from our approval service, which 34 Southwest Technical Products Corp..... • . .. • .... .32 you may return without purchases and cancel service at MISCELLANEOUS any time . Jamestown Stamp, Dept. A15EG, Jamestown, 35 Tri-Star Corp...... 91 N .Y. 14701 . WINEMAKERS: Free Illustrated catalog yeasts, equipment. Semplex, Box 12276P, Minneapolis, Minn. 55412. 36 U.S. Pioneer Electronics Corp...... SECOND COVER, I DO-IT-YOURSELF 4 United Audio Products Corp...... FOURTH COVER NEW--0oncept In ·cement. Bonds wood, metal, stones, plastics. Anything. Used by Jewelers, Carpenters, Metal­ TELEPHONES UNLIMITED, equipment, supplies. Catalog workers, Craftsmen. $3.00. Butco, 1626 2nd Ave., N.Y.C. C~RED ADVERTISING .....103, 104, 106, 108, 110, 111 50 cents. Box 1654E, Costa Mesa. Calif. 92626. 10028. JANUARY 1975 111 ~------,.-~."_ · ' 3i~~~;~~~~:;:g~~~~~~1KIT ·_·.· '·.·,._ _. .,, ' _:___:·_t'-- ulate 3 independent strings of colored lamps (i.e. "lo\Vs"-reds, "middles"-greens, "highs"­ blues. Just connect hi-ti, radio, power . lamp etc. & plug ea. lamp string into own channel (max. 300w ea.). Kit features 3 neon indicators, color intensity controls, controlled individ SCR circuits; isolation transformer; custom plastic housing: instr. Stock No. 41 ,831AV ...... $18.95 Ppd • • • • • • • • • • • • • • • • • • • He-Ne LASERS ... $99.50 up! 12v WIND-POWERED GENERATOR Top quality Spectra Physic lasers feature Cheapest continous source of elec­ TEMqo mode, internal mirror plasma tub.es w/ tricity available! Attach to 12v truck batt. 10,0uO hr. life, self-starting cold aluminum (not incl) and get free electricity from cathodes, low noise & ripple, guaranteed the wind. Needs only 7 mph wind - 15 output power stability and more for demand­ amps output in 23 mph wind; double the ing lab work. 18-mo. mfr. wty. l 15v AC watt-hour output of ordinary radio chargers. (A) 0.5mW . .. 0.88 Beam Dia., 1 mRad Oiverg. Perfect remote area and alternate energy #79 070AV (2.6x8.5x14.8") ...• , .... •. , ...... •.•...... $99.50 Ppd. source. Big 6" propeller (Albers Air-Foil princ.) turns 200w ~enerator; governor (Bl i.omw . . . (as above) #79,073AV ...... , .....$125.00 Ppd. prevents overcharging/action. Price includes packing & shipping. (C) 4.0mW .. • 0.8 Beam Dia, 1.1 mRad Diverg. No. 19, 189AV (10"-145 lb.) ...... $475.00 Ppd. #79,079AV (3.9x5.5x15.6") '' " " .. " " .. " .. " .. " .. """ " ...... $465.00 Ppd. • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • KNOW YOUR• ALPHA FROM• •THETA! • "FISH" WITH A MAGNET For greater relaxation, concentration, liste_n_ to your Alpha-Theta brainwaves. Ultra-sens1t1ve electrode headband slips on/off in seconds­ Go treasure hunting on the bottom! Fascinat­ '______·· _.___ - ._-._·····.-__ ...::'_;.:.:.___ , _·._._· ' ' . . eliminates need for messy creams, etc. Atch'd ing fun & sometimes profitable! Tie a line to to amplifier, filters brainwaves, signals beep for our powerful new specially designed 150 lb. : . . >:.,, ·.; ' p . _.,. ; ea. Alpha or Theta wave passed. Monitoring pull PVC coated Magnet-dropit overboard in . -~~ - .• '! · · ' button stimulates Alpha sound; audio & visual bay, river, lake or ocean. Troll 1t along (l. E. D.) feedback. Reliable, easy-to-use unit comparable to costlier models. Com­ bottom-your "treasured" haul can be out­ pletely safe. Comprehensive instruction booklet. board motors, anchors, other metal valu­ ables. Has 6 stacked ceramic magnets. Lifts No. 1635AV (8x3x4"; 24. oz .) ...... $134.50 Ppd. over 150 lbs. under water! No. 71,135AV •.. (3-1/4x3-7/8") ...... $17.50 Ppd. ~~w7~~~1~~~~R~~R·: -~~l·T·' .. ' • . . . ' ' . '' ...... ' ' . .. ' .••••. . . ' .. •• .$55.00 Ppd. 75-LB. PULL (1 LB) W/ 3 CERAMIC MAGNETS DELUXE "ON" TIME MONITOR-Measures and records% No. 71, 150AV .. • (1 -11/16x3-1/4") ...... _...... $11.00 Ppd. No. 1652AV . •.. (15x10x6"" ) ...... $349.50 Ppd. •NEW! • • KIRLIAN• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • PHOTOGRAPHY KIT! Experiment in the fascinating new ASTRONOMICAL MIRROR KITS field of "Kirlian electrophotography-" Grind your own mirror for powerful images obtained on film without telescopes. Kit contains fine annealed pyrex camera or lens by direct record­ mirror blank, tool , abrasives, diagonal ing of electric charge transmitted by mirror, and eyepiece lenses. Instru­ animate & inanimate objects. Each 11 ments you build range in value from $75.00 aura'' differs- animate aura said to to hundreds of dollars. change corresponding to physical changes. Kit incls. portable darkroom, double transformer isolated from power source; instrs. Stock No. 70,003AV. '' . ' ' . ' . ' .... ' ' . '' - .4V2" diam. 3W' thick . ' •• ••.$13.75 Ppd. Stock No. 71,938AV ...... $49.95 Ppd. Stock No. 70,004AV ...... 6" diam. 1" thick ...... $19.75 Ppd. "HIGH VOLTAGE PHOTOGRAPHY" b~ H.S. Dakin Stock No. 70,00SAV ...... , ...... 8" diam. 1%" thick ...... $32.75 Ppd. No. 9129AV. !60-PG. PAPERBACK BOOK) ...... $5.00 Ppd. Stock No. 70,00SAV ...... 1O" diam. 1%"thick (30 lbs.) .• . .. , ,.$58.00 FOB DELUXE KIRLIAN PHOTOGRAPHY SET . Stock No. 70,007AV ...... 12W' diam. 21/a'' thick (46 lbs.) .••• , ...$98.50 FOB •No. •72, 053AV• •, . , ..•• ...... • • ••....•• •• ...•• •...• •••• , ...•.• .••..• •. . • ..•$399.00 • •Ppd. • • • • • • • • • • • • • • • • • • • • GET A CHARGE 3" ASTRONOMICAL FROM THE SUN! REFLECTING TELESCOPE Our 12V Solar Battery Charger allows See stars, moon, planets close-up! direct conversion of light-to-electricity. 30 to 90X. Famous Mt. Palomar Type. Compact panel put on a boat can Aluminized & overcoated 3" diameter automatically charge its 12V battery f/10 primary mirror, ventilated cell. Fork type over entire daylight period. Use any­ equatorial mount. Durable PVC tube. In­ where for a trickle charge. Big value. cludes l" F. L. 30X Ramsden, Barlow it comprises 30 11z v silicon solar cells in lens to triple power, 3X finder s·eries w/diode. telescopes, hardwood tripod. FREE: "STAR CHART", "HOW TO USE" book. No. 71,971AV (AB , 30 W-HRS./WK.) ...... $89.95 Ppd. Stock No. 85,240 AV ...... $49.95 Ppd. 9 x 18" HI CURRENT MODEL (6W, 12V, 500 mA) DELUXE 3" REFLECTOR TELESCOPE .... • , .#80,162AV ..•• , • , • , •. • ...••$79.95 Ppd. No. 72,010AV (AB. 150 W-HRSJWK.) ...... $420.00 Ppd. 4W' REFLECTOR (45X to 135X) ...... #85, 105AV .... , •.. , , .• • •..•$149.50 FOB 6 x 6" LO VOLTAGE MODEL (1.5V, .38','.i, 250 mA) No. 42, 172AV ...... , ...... _.• •.. , _. •,. , .....$49.95 Ppd. 4W' REFLECTOR W/CLDCK DRIVE ...... #85,107AV ...... $189.50 FOB 6" REFLECTOR (4BX to 360X) ...... #85, 187AV •.. . .•..... •... •.$249.50 FOB -P!'ll~..9!..P6!i"ii!REP.FLECTOR W/CLOCK DRIVE •••.. , , . ••#85,086AV .•••. ,,., .••• • . , .$285.00 FOB MAIL COUPON FOR

GIANT FREE How Many Stock No Description CATALOG! I 164 PAGES • MORE THAN ~- I UNUSUAL 0 PLEASE SEND I 4500 BARGAINS I GIANT FREE Comj:lletely new Catalog. Packed with huge selection of telescopes. mi­ croscopes, binoculars, magnets. magnifiers, prisms, phOto _components , I CATALOG "AV" I ecology and Unique Lighting items, parts, kits, acce~sones - many hard·to·get surplus bargains. 1oo·s of charts, rllustrat1ons. For hobby· 1sls, e11perimenters, schools, industry. I Add Handling Ch11.: $1.00, Orders Under $5.00, 50C, Order:.:•..:O:..:•:::•r_$:.:5:.::.D:.:O-+---­ I EDMUND SCIENTIFIC CO. 300 ·uscorp Buildin1, B1rrin1ton, N. J, 01007 I I enclose D checfc D money order for$____ TOTAL$ '------I Please rush Free Giant Catalog "AV"

Name------~ I NAME------I

Address------• ADDRESS ------• z;•----- I c1rv·------STATE_____z1p____ ..I L!it~•------_!!at!..------_ _ _ L.., - ~ ~ ---- ._ -- _, - ~ · ----- ___ -. 112 CIHcLE NO. 15 ON READER SERVICE CARD POPULAR ELECTRONICS Printed in U.S.A. What is itthat feels good, sounCls good· and will go anywhere with you?

Pickering's Model0A·3 dynamic open audio lightweight headphones.

Expanded Listening Enjoyment. Just plug the Sound Perfection. You have to listen to believe. special adapter into the earphone jack of any Open Audio. Enjoy the sound. Yet, be part of Mono Cassette Recorder, Portable Radio or TV what's going on around you . That's the big thing Set and plug the OA-3 into the special adapter about "open audio". and enjoy total sound everywhere you go. Prediction. The OA-3 will be your favorite "com­ Revolutionary. So slender. So light. So comfort­ ponent" in your hi-fi stereo system. $3995 able to use over long periods of time. For further information write to: Pickering & Co . lnc.,.Oept. PE,101 Sunnyside Blvd., Plainview, New York 11803

I• PICKERING I "for those who can ihearl the difference" CIRCLE NO. 29 ON READER SERVICE CARD Many serious music lovers are not satisfied The 1229Q is too new for test reports to have unless every component in their system is the very appeared, but reports on its immediate finest in its class, with cost secondary. The 1229Q, predecessor, the Dual 1229, indicate why it was Dual's highest-priced multi-play turntable, is one of the largest selling quality turntable ever made. these "no compromise" components. Stereo Review called its rumble measurements The 1229Q is a full-sized turntable with a "among the best we have yet made on a twelve-inch dynamically balanced platter that turntable'.' High Fidelity said, " It takes one step weighs a full seven pounds. its massive platter is further the progressive improvements that have driven by Dual's powerful Continuous-Pole/ made top Dual models among the most popular synchronous motor. turntables in component systems for the better The 8-3/ 4" tonearm is mounted in a true part of a decade, to judge by readers' letters'.' gyroscopic gimbal that centers and balances it . Stereo~ HiFi Times' noted, " I unhesitatingly within both axes of movement. All four tonearm .. recqm.rrierid'i't to anyone looking for the best pivots turn on identical low-friction bearings . po~sible record playing equipment:' And Popular permitting flawless tracking at as low as 0.25 Electronics rated it "the equal of any combination gram. And since a turntable of the 1229Q's calibre of record playing components known to us '. ' is used most frequently in the single-play mode, Of course, not everyone can afford the the tonearm is designed to trackat precisely the 1229Q's price: $259.95. But every Dual turntable, correct angle in that mode. With the exclusive starting with the 1225 at $129.95, provides the Mode Selector, tracking angle can be instantly same high quality materials, carefully finished adjusted for correct tracking at mid stack in the parts and meticulous quality control that have long multi-play mode. earned Dual its reputation for reliability. Low capacitance tonearm leads and an Thus which Dual you select is not terribly anti-skat ing_system with separate calibrations for important.Your choice can be made in terms of the conical, elliptical and CD-4 styli, make the 1229Q level of refinement you require. And if, li ke many compatible with any stereo and four-channel music lovers, you require every refinement it is cartridge available or likely to be available in the possible to have in a multi-play turntable, chances foreseeable future. Other features include a are you too wi 11 choose the Dual 1229Q. calibrated illuminated strobe with adjustable "United Audio Products viewing angle, and cueing damped up as well as [IJ 120 So. Columbus Ave., Mt. Vernon, N.Y. 10553 down to prevent bounce. Exclusive U.S. Distribution Agency for Dual CIRCLE NO. 4 ON READER SERVICE CARD