3UILDWOUR OWN BURGLAR ALARM, JULY POPULAR 1960 35 CENTS' i H, -F1 HAM, & cIT'I_ DI sw(L 4 ^ It ;oinplete Plans For: 4 \v ..Reflex Pocket Radio rS, t5, -- Bubding ad =. Rádiomañ's L1mp.:. 'rJ}_ r ll Abbut:. - WY. aa ShiPShaping ' A>gr7.1t1. Marine-Radio- ff 'Microphones .- ,.. .. .. for Hi'Fi [ 11. 1`` I 1'/ .5:.':_ o- - Fi NEE 1 - - Magriétió. Amplifiers_. what they are.- 'how they work Imémotimmlm AmericanRadioHistory.Com 11 - ! /3 on Audiotape on 11/2 -mil MYLA THAT'S RIGHT! Audio Devices has cut at least 31% off the price of its premium -quality Audiotape on 1162 -mil "Mylar." Now you can enjoy all the advantages of DuPont's fabulous "Mylar" for little more than the cost of ordinary plastic -base tape. Audiotape on 11 -mil "Mylar" is the finest tape in the Audio - tape line. Its tough, durable "Mylar" base and professional - quality oxide make it the perfect tape for schools, recording studios, radio and TV stations, military users-as well as dis- criminating home recordists. See your Audiotape dealer as soon as possible. At the new low prices, his stock will move fast. (Similar price reductions have also been made on Master "Low Print -through" Audiotape on 'fa-mil "Mylar.") "Mylar" is DuPont's trademark for its polyester film-the toughest, most durable recording tape base material known to man. "Mylar" cannot dry out or become brittle with age. Radi- cal differences in temperature and humidity have no effect on it. Recording tapes on "Mylar" can't break or stretch in normal use, regardless of temperature or humidity. Most importantly, "Mylar" is a known, tested base material-proven by years of use in telemetry, automation and electronic computing applica- tions. Millions of feet have been recorded by professional and amateur sound recordists, too. AUDIO DEVICES, INC., 444 Madison Ave., N. Y. 22, N. Y. In Hollywood: 840 N. Fairfax Ave. In Chicago: 5428 N. Milwaukee Ave. AmericanRadioHistory.Com r T YOU BUILD YOU BUILD Broadcasting Signal Transmitter Generator iS As part of N.R.I. Communi- cations Course you build this N.R.T. sends kits of parts , low power Transmitter; use to build this Signal Gen- it to learn methods required erator. You get practical of commercial broadcasting experience, conduct tests to operators, train compensate Radio frequency amplifiers, for FCC practice aligning a typical I.F. video ampli- L license. fier in TV circuit, many other experiments. mmrmia lomm.v._. YOU BUILD Va cuum YOU BUILD AC-DC Tube Voltmeter Superhet Receiver to get practical earn 'Use it es,e-once. N.R.T. servicing training fixing neighbor-' ec ts in spare extra cash supplies all pa ts, every- time, gain knowledge tc lief¡ you work With thing is yotrs to keep. 1 y in Radio, Television, Celor TV. Nothing takes the place N.R.I. training you wo t .n circuits of practical experience. 4. common to both Raclin aid 7:V. Equip- You get actual servicing ment you build "brings things lie" experience by practicing learn in 'as já you N.R.I.'s to -under- with this modern receiver; stand lessons. 64 page FREE,. ;azg you learn -by -doing. shows all equipment ycu get - p11 I r. ' II i _ . by Practicing 'at Home 'WHAT GRADUATES DOIAND SAY NEED FOR TECHNICIANS INCREASING Chief Engineer "1 ant Chief Engineer Fast Growing Field Offers Good Pay, Bright Future of Station KGCU in Today's OPPORTUNITY field is Radio -Televi- and can do. So plan now to get into Radio -TV. Mandan. N. D. I also your job while training with N.R.I. You my own spare time sion. Over 125 million home Radios plus 30 Keep have spare time. N.R.I. is business servicing high million sets in cars and 40,000,000 Television learn at home in your frequency two.waycom- sets mean big money for trained Radio-TV oldest and largest home study Radio -TV School. have successful for more munications systems." I Technicians. More than 4,000 Radio and TV Our methods proved R. BARNETT. Bis- Broadcasting stations offer interesting and im- than 40 years, provide practical experience. marck. North Dakota. I portant positions for technicians, operators. Soon after enrolling, many N. R. I. students start Paid for Color television, portable TV sets, Hi -Fi, other to earn $10, $15 a week extra in spare time sets. Many open their own full time Instruments a; It*`` developments assure future growth. fixing ' It's the trained man who gets ahead. The fellow Radio-TV shops after getting N.R.I. Diploma. "I am doing very well who uses his spare time to develop knowledge and Find out more. Mail Coupon. Cost is low, terms in spare time TV and -.Br skill gets the better job. drives a better car, lives easy; includes all equipment. Address: National Radio. Sometimes have a a home, is respected for what he knows Radio Institute, Dept. OGD-4, Washington, D. C. three TV jobs waiting in better and also fix car Radios q' for garages. I paid 4, 4 for ;, Send for TFegBCs>/T :: instruments out of earn- - -- ` S FR VICINO MAIL COUPON -NOW ings." G. F. SEAMAN, LESSON New York, N. Y. t, A NATIONAL RADIO INSTITUTE Has Own and CATALOG Dept.OGD-4Washingiton 16, D. C. ' ' Cattet TV Business Job and Mail me Sample Lesson and 64 -Page Catalog, C+. will Please write plainly.) "We have an appliance it -- OPPsltosilits FREE. (No Salesman call. store with our Radio FREE lot i' Name_ Age___ and TV servicing, and LI RADJO-TV get TV repairs: During my Army service, NRI VETERANS TECNNJCJANS Address- training helped get me Available a top rated job." \V. M. under City Zone- --State WEIDNER, I Fairfax, G.I. Bills ACCREDITED MB.IBER, NATIONAL HOME STUDY COUNCIL, South Dakota. POPULAR ELECTRONICS IS publishetI monthly byy Z,ITDavia Publishing Company. William B. Zia. Chairman of the Board (1946- 1953). al 434 S. W..bes,' Ave.. Chi.ago 5. Ill. Serond.elassi posi ge rani,) at Chiragn. Illinois Atinhorited hV Post Otflre Deuu,'linenl. Ottawa Caned:,. as a ,nd-elass mailer. SUBSCRIPTION RATES: One year U.S. and possessions. and Canada $4.00; PunAmertcan Union Countries $4.50, all other foreign countries, $x.uQ. AmericanRadioHistory.Com JULY 1960 VOLUME 13 NUMBER 1 Electronic Construction Projects One -Transistor Pocket Radio Alvin Mason 43 Earphone Booster Amplifier Louis E. Garner, Jr. 46 Electronic Burglar Alarm Ed Duda 62 Radioman's Lamp Charles Coringella, W6NJV 69 D.P.D.T. Switches in Power Circuits Kenneth Richardson 98 Audio and High Fidelity Build a Picnic Speaker Luis Vicens 54 Inside the Hi -Fi Microphone Joseph Marshall 55 How to Extend the Life of Your Records John Milder 77 Communicating Through the Earth ..J. C. Fischesser 87 Stereo Amplifier -Preamplifier 90 Electronic Features and New Developments Operation Radio Control 39 TV Explores Deep Wells Harry J. Miller 48 New Developments in Product Design 50 Ship -Shaping Marine Radios Leo G. Sands 59 Magnetic Amplifiers-How They Work, What They Do.... Ken Gilmore 71 Test Instruments-The Sweep Generator G H. Harrison 80 Transistor Topics Lou Garner 84 Carl and Jerry: Tussle with a Tachometer John T. Frye, W9EGV 94 Amateur and SWL Notes from the Editor: SWL Registration Oliver Read, WIETI 6 FCC Report: Computers for FCC Robert E. Tall 8 DX'ing Down Below Tom Kneitel, WPE2AB 51 The Strange Inhabitants of 75 -Meter Phone.. James F. Van Delta, WA2FQZ 66 On the Citizens Band Tom Kneitel, 2W1965 76 Across the Ham Bands: Putting Up Antennas....Herb S. Brier, W9EGQ 91 Short -Wave Report Hank Bennett, W2PNA 97 Departments Letters from Our Readers 12 POP'tronics Bookshelf 18 New Products 24 Tips and Techniques 34 Cover photo courtesy ITT Laboratories Copy 'slit y 1360 by ZIFF-DAVIS PUBLISHING COMPANY. All rights reserved. 2 POPULAR ELECTRONICS AmericanRadioHistory.Com "All personnel . clear. the firing area .. stand by for countdown .. minus 10 .. YOU MAY HANDLE A SITUATION LIKE THIS... If you measure up to the Aerospace Team A man in this situation requires cool judge- will have the opportunity to work with the ment and an aptitude for advanced technical intricate equipment of the Aerospace Age-the training. This is the kind of man who can age of air and space travel. You will enjoy measure up to the qualifications of the U. S. steady advancement and solid security. And Air Force. He is the kind of man who can you will be superbly prepared for the future. build a career in the Aerospace Age that will If you would like to learn more about the be meaningful and rewarding. many unique advantages that go with a Are you that man? As a trained and ex- career in Air Force blue, fill in and mail this perienced Air Force technical specialist, you coupon today. U.S. AIR FORCE There's a place for tomorrow's leaders on the Aerospace Team PASTE COUPON ON POSTCARD AND NAIL TO: Airman Information,Dept. MP07, Box 7608, Washington 4, D. C. Please send me more information on my opportunities in the U.S. Air Force. I am between the ages of 17-34 and reside in U.S.A. or possessions. Name Address City Zone County State L _t July, 1960 3 AmericanRadioHistory.Com PQPULAI Editor & Publisher OLIVER READ, W 1 ETI Managing Editor JULIAN M. SIENKIEWIC2, WA2CQL ELECTRONI CS Feature-Editor ' World's Largest -Selling Electronics Magazine FURMAN HEBB ' ' Ayt Director. Average Net Paid Circulation 295,979 ALFONS J. REICH Aºsociote Editors RICHARD A. FLANAGAN MARGARET MAGNA PERRY WINTER, K2VLR Editorial Assistant COMING NEXT MONTH DOLORES GIMBEL' Contributing Editors H.