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 -- -- --- - ~:- ---- - - --- --. -!­ :~-~~--~- ~~~.,~- 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