Electronics U.S

POPULAR AUGUST

CENTS and Canada ELECTRONICS U.S.

- RADIO 4MATEURS R/C SWL AUDIO

ehind tl-e U. L. Lebel Use Cadmium Photccells Geiger Counter Probes R/C Printed Circuifry

--4011111.

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AmericanRadioHistory.Com You Build THIS TRANSMITTER I WILL TRAIN YOU FOR with Parts I Send

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EARN COIVIVIUFICATIONS Practicin at Home in S are Time Use parts I send for Actual Experience The Communication Course I offer mitter Operators, Re- Oper- My Training Leads to Jobs Like These you is backed by NRI's 40 year mote Control ators, Service and BROADCASTING: Chief Tech- record of training men at home. Maintenance Techni- Power nician, Chief Operator, well- illustrated lessons give etc. Mail Cou- Monitor, Remote Control Oper- My cians, ator. SHIP AND HARBOR you the basic principles you must pon. Find out, without Operator, Radio - RADIO: Chief have to assure success. My skillfully de- obligation, what I of- telephone Operator. GOVERN- can MENT RADIO: Operator in veloped kits "bring to life" what you fer. NRI training of Army, Navy, Coast Guard, For- learn from my lessons, give you practical assure you more estry Service Dispatcher. POLICE better things of experience on circuits common to BOTH the RADIO: Transmitter Operator, life; can help you qual- Service Technician. AVIATION Radio and Television. You build the ify for high pay and RADIO: Plane Radio Operator, low -power Broadcasting Transmitter Airport Transmitter Operator. promotion when times a Pickup Operator, shown above (at left). You put this J.e E. s Hlr TELEVISION: are good, enjoy great- tadi. IasHnt Voice Transmitter Operator, TV station "on the air," and conduct pro- NstiRIOl Technician. er security when jobs cedures required of Broadcasting Station are scarce. Progres- "" " "' "'' My book shows other valuable AT HOME operators. sive, ambitious men consider,RadioTele- I TRAINED THESE MEN equipment you build and keep. vision an outstanding field for their life's "1 std not know a thing "1 have progressed very work. My 64 -page book, "How to 3e a po- :bout Radio before I rapidly. My present gives impor- sirion is Television cnro1led for your train - Television's Rapid Growth Success in Radio -Television," Studio Supervisor with alp. Now I have a job tant facts about America's fast growing k ED D Television, Studio Engineer at Jobs, Prosperity industry, shows what my graduates are Fre- I tadio Station KM MJ." Making Good IL. \\ ichita. -Elmer doing and earning. You see equipment you y aldt, 3026 Stadium. - -Bill Delzell,. Central Radio is bigger than ever with over 3000 actual t. \1 ichita, Kansas. Cicy, Nebr. practice with at home. Also, you get Stations on the air making "A former employee "My position with Broadcasting sample lesson, see how easy it is to learn Recording recommended National WNBT is vide- control good jobs for Chief Operators, at home. I send both FREE. Radio Institute training engineer on the RCA and Remote Control Operators, Power employed 1 owe a to me. Now color project. there's Coupon as transmitter operator lot of my success to Monitors, Technicians, etc. Now Get Facts Now -Mail in "-Albert your testbooks."- Stations are Harrisburg. Television, too. About 200 TV You don't have to leave home or giveap - Mal - Herr, New Cumber 'Warren Deem, the with many more being built, Many of land, Pa. verne, N. Y. on air job to take NRI courses. hundreds of additional sta- my than the total ?. "Am with WCOC. construction of graduates make more Happy with my job. AVAILABLE TO tions authorized, and new TV Station ap- cost of my training in a few weeks. Mail can't be NRI course month. Think J. E. SMITH, President, beat. Passed exam for plications being filed every coupon now. ," 1st class Radio-phone VETERANS of the demand this is creating from coast National Radio Institute, Dept. 5HD4 license with no trouble." to coast for Pickup and Voice Trans- Washingtoi 9, D.C. OUR 40th YEAR. -Jesse W. Parker, UNDER G.I. BILLS Meridian, Miss. in I Also Have a Course Mr. J. E. SMITH, President, Dept.5HD3 National Radio Institute, Washington 9, D. C. Mail me 64-page Book FREE. (No salesman will call. Plea,e Radio TV SERVICING write plainly.) Age If you prefer a career in Name_-

E Radie- Television Servicing, I'll train you at home for it. AdJ Course includes many Kits City Zone_ State__. of pare. My book shows that many make $10, $15 a T write In date week EXTRA fixing sets V G S of discharge Moat nwr CON11- while training. /0n0.0 watet. NATION. Publishing Company. William B. Ziff. Chairman of the Board 19.10- POPULAR ELECTRONICS is pu'.dished monthly by Ziff -Davis 1954 et the Post 'Jence. Chicago, Illinois. 1053), t 64 E. Lake St., Chicago 1. III. Entered as second class matter August 27, all foreign L.S. and possessions, and Canada Pan -American Union Countries $3.50: otter SUBSCRIPTION RATES: One year countriesCna $3.00l 3 August, 1955

AmericanRadioHistory.Com AUGUST 1955 POPULAR VOL. 3- NUMBER 2 EDITOR OLIVER READ, W1ETI

MANAGING EDITOR O. P. Ferrell ELECTRONICS TECHNICAL EDITOR H. S. Renne

Registered L. S. Putout 011ue FEATURE EDITOR Norman Eisenberg CONTENTS ASSOCIATE EDITORS M. C. Magna Charles Tepfer Automatic Factories E. G. Louis 21 ART EDITOR A. Reich Electronic Fish -Finders 27 J. CONTRIBUTING EDITORS Behind the U.L. Label E D. Morgan 31 J. T. Frye L. E. Garner, Jr. H. Bennett R. P. Turner Science Meters a Heart Muscle 34 R. Legge H. Pollack "Mr. Meticulous" Makes Transistors 37 H. S. Brier "Over the ART DEPARTMENT Horizon" Transmission 39 Frank Sayles (Director) TV for J. A. Golanek M. Whelpley Parking Lots 41 ADVERTISING DEPARTMENT Using the CdS Photocell Marvin Lubin and Wallace Samuelson 42 NEW YORK (MU 7-8080) Lingo of the Schematic L. L. Osten -Adv. Dir. George Berry 44 Wm. G. McRoy-Adv. Mgr. Positive T. Suito Flash -Gun Tester Harvey Pollack 46 Build Your Own Applause CHICAGO (AN 3.5200) Meter Louis E. Garner, Jr. 47 James Weakley Checking a Typical Clock Radio. H Leeper 52 LOS ANGELES (Mich. 9856) Build John E. Payne -W. J. Fitzgerald Your Own Geiger Counter Probe Carter Robertson 54 Electronic FF'DAl- "Whistler".. Rufus P. Turner 57 Jig Makes Solder Gun Tips Z Copyright 1955 Harvey Pollack 62 (AB Rights Reserved) The $1.60 Signal Generator Frank H. Tooker 64 /NG & Carl Jerry. John T. Frye 66 ZIFF -DAVIS Printed Circuitry for R/C Paul F. Runge 74 Thin PUBLISHING COMPANY -Skin Chassis Cuts Costs Richard C. Saunders 90 W. B. ZIFF (1898.1953) FOUNDER

POPULAR ELECTRONICS Audio and Hi-Fi Section Also Publishers of RADIO & TELEVISION NEWS Disc and Tape Review Bert Whyte 77 Editorial and Executive Offices Birth of a Loudspeaker 79 366 Madison Ave., New York 17, N.Y.

Distortion in Hi -Fi Equipment (Part 3) Norman H. Crowhurst 82 PRESIDENT B. G. DAVIS What Is an Audio Watt?. . Eugene F. Coriell, Major, USAF 84 VICE -PRESIDENTS Square -Wave Converter... Howard J. Carter 86 H. J. MORGANROTH M. FROELICH SECRETARY-TREASURER DEPARTMENTS G. E. CARNEY MANAGER From the M. Ed. of POP'tronics 8 CIRCULATION M. MICHAELSON Letters from Our Readers 10 BRANCH OFFICES The Chicago 64 E. Transmitting Tower Herb S. Brier 68 (1), Lake St. Los Angeles (1 4), Stotler Center, Ama- Touring with Roger Legge 70 900 Wilshire Blvd. Tuning the Short -Wave Bands Hank SUBSCRIPTION service: Bennett 71 All communications concerning mute Iptlonn should be addressed to Cir- R/C Notes 73 crculation Dept.. 64 E. lake St.. Chicago I . Ill. Include yy r old address as well as new-enclosing if penible an After Class.. 88 address label from a recent issue of this magazine. Allow at least week. What's the PE Answer2 for change of address. 96 CONTRIBUTIONS: POP'tronics Bookshelf Contributors are advised to retain a 100 copy of their manuscripts and Illus- Contributions mailed Tools & Gadgets toatthesNew 1 Editorial dOOlce a 106 must he accompanied by return postage. Tips Contribution. will be handled with rea- and Techniques 109 care. but this m gazine as- smablesumes n responsibility for their safety. Glossary of Electronic Terms Any copy accepted is subject to what- 124 eV( adaptations and revisions are nee- ary but east the , ul retneo s Of this Standardized Wiring Diagram Symbols publication. Payment cover. all au- 126 thor'. contributors. and contestant's rights. title. and interest In and to (Also see page 6) he malerl:it s rented nod will he made .It nt rate. erptim Cover Painting by Ed Valigursky All photo.) and drawlaer will be consider id as part of material purchased. 4 POPULAR ELECTRONICS

AmericanRadioHistory.Com START NOW -PAY LATER- Financea Plan GREAT OPPORTUNITY FIELDS and Easy Monthly Payment Plan. Also part - Conditions are changing. Many "one operation" jobs that time employment help for students. have paid well will not last. Don't be satisfied with a "no future" Get FREE Book job. Whether 17 or up to 45 years of age, train the Coyne Send coupon for 48 page way for a better job and a real future in ELECTRICITY or illustrated book "Guide to -RADIO, fields thatoffera worldof opportunities. Careers in Electricity and Tele- TELEVISION vision-Radio." No cost; no CHICAGO SHOPS obligation; no salesman will YOU can TRAIN in great call. Get vital facts now ! Train on real, full -size equipment at COYNE where thousands of successful men have trained for over 56 years B. W. COOKE, President -largest, oldest, best equipped school of Its kind- established COYNE ELECTRICAL SCHOOL education or previous experience 500 S. Paulina St.,Chicago 12, î11., Dept. C5.71H in 1899. No advanced Send BIG FREE book and details of your needed. TRAINING APPROVED FOR VETERANS. training offer. This does not obligate me and no salesman will call. I am interested in: Electricity Television -Radio B. W. COOKE, President FOUNDED 1899 Name

A TECHNICAL TRADE INSTITUTE OPERATED NOT FOR PROFIT Address PAULINA STREET, CHICAGO, Dept. C5-71H 500 S. City State ELECTRICITY * RADIO * TELEVISION * REFRIGERATION * ELECTRONICS COYNE offers LOW COST C s T E E ot Training in ÉIfSpare Time AT HOME RAS SEND COUPON FOR FREE The future is YOURS in TV -RADIO ! A fabulous field -good pay- fascinating work - BOOK a prosperous future! Good jobs, or independence and full details, in your own business! including easy Payment Plan. Coyne brings you the first truly fewer cog, MODERN-QUALITY Televi- sion Home Training; training designed to meet Coyne standards. Not an No obligation, no old Radio Course with Television "tacked on ". Here is MODERN TELE- salesman will call. VISION TRAINING including working knowledge of Radio. Includes TV. No Radio background or previous experience needed. UHF and COLOR COONS Personal guidance by Coyne Staff. Practical Job COYNE ELECTRICAL SCHOOL moo- Guides to show you how to do actual servicing B. W. 000BE, Presldeet Television Home Training Div. jobs -make money early in course.With Coyne 500 S. Paulina St., Chicago 12, Television Home Training you pay only for Dept. C5 -EIT7 no costly "put together kits ". your training, Send Free Book and details on Television Home Training. This does not obligate me and no salesman will call.

Coyne -the Institution behind this Name 500 S. Pauline St., Dept. C5 -HT7, Chicago 12 training ... the largest,oldest,hest Address A TECHNICAL TRADE INSTITUTE OPERATED equipped residential school of its NOT FOR PROFIT kind. Established 1899. City State August, 1955

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NEW PRODUCTS l Unique Features. Advanced Design in Hi -Fi Units.. 26 A.C. -D.C. Converter 30 Powerful Wireless Intercom 36 Electrostatic Tweeter 40 Enclosure Has Adjustable Port 40 Filter Eliminates TVI 55 Unbreakable TV Lamp 55 Low -Cost Intercom 56 Start your hobby off right Plastic Tape Reels 56 with this professional CW Short -Wave Hi -Fi Tuner 56 transmitter kit. 50 Watts Indoor Rotating Antenna 61 input on 80, 40, 20, 15 and 11 -10 meters. Packs enough power for world -wide radio contacts with just a simple antenna. No antenna tuner COMING NEXT MONTH needed -single knob band - switching- crystal controlled POPULAR ELECTRONICS oscillator - powerful 807 transmitting type output tube. Easy to build -safe to operate! Kit is furnished CIC -"The Navy's Electronic Clearinghouse" complete with built -in power Extra Jobs for supply, tubes, cabinet, wir- the VOM ing instructions and antenna Stroboscope for the Electronic Workshop suggestions. Cat. No. 240- 181 -1 -Viking The Big Ear "Adventurer" Kit, less crystal and key $54.95 Picking Your Record Player or Changer

Building a Miller Hi -Fi JOHNSON KEYS AND Tuner PRACTICE SETS STANDARD KEY -Heavy die High -Fidelity Audio cast base. Smooth adjustable Kits Radio Control bearings. Provision for plug- Short -Wave Listening What's ging in semi -automatic keys. New Contacts are 'Vs coin silver. A How It Works How to Make It How high quality key at a low cost. to 114 -310.. $2.60 Net Price Use It Carl & Jerry Tips & Techniques PRACTICE KEY -an inexpensive practice key - perfect in design for the average begin- IN THIS MONTH'S ner. All the metal ports are nickel plated except the base. Furnished with an adjustable RADIO & TELEVISION NEWS key arm spring and smooth action bearings. Contacts are (August) of t/s ' coin silver. 114 -300 $1.75 Net Price PRACTICE SET- Constant fre Techniques of Recording Wildlife quency buzzer and key on a 4"x 6" molded Bakelite base. An Amateur U.H.F. Transceiver May be used singly or in pairs for code practice. Marine Electrolysis 114 -450 54.25 Net Price Frequency- Modulated Wireless Record Player For more information on the Viking "Adventurer "or Johnson's complete line keys of - see your electronic ports distributor or write to: CAM, Get Looped! Transistorized Headlight ,( E. F. JOHNSON COMNI: \`1' Dimmer 3013 Second Ave. S.W., Waseca, Minn. 6 POPULAR ELECTRONICS

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MY TRAINING IS SO SIMPLIFIED EVEN A THIRD- GRADER CAN MASTER IT!

If you've been looking for a chance to improve yourself - to get into a high -paying field with a good future - but have been putting it off started my RITA Radio-FM- Televi- When Nick Pakinas because you don't think you his 7- year -old daughter, Sharon, kept right L. C. Lane, LS., M.A. sion Course Radio-Tele- lessons in their schooling, or President, up with him as he progressed in his have enough vision Training Asso- home in Bothell, Washington. enough time, here is your ciation. Executive Pierce School Today, Sharon shown here in a photograph repro- Director, - chance to make your dreams of Radio & Television. duced from the pages of the Seattle Post-Intelligencer- in is the youngest FCC -licensed amateur radio operator come true. the Pacific Northwest, and possibly the nation. Sharon Pakinas was only in the Third Grade Sharon can do it, why can't you? If when she studied her father's course from RTTA The answer is YOU CAN! and passed the FCC Examination for an amateur Via. R F Slgnnl Genermar YOU radio operator's license. Many of my students GET ALL have had no more than a grammar school edu- THE -to- understand lessons especially EQUIPMENT cation. My easy SHOWN prepared for home study make it possible for AND students with no previous experience to become MORE! skilled television technicians.

still j ob and Super.Het a full -time down Radio Rece ver You can methods the same successful VETERANS! M HOME by Combinolion Vollmeter train of men -many Ammeter- Ohmmeler hundreds to help I used training - Approved to Train Veterans school School Fully grammar My more than Publie Address Write discharge no System under new Korean G.I. Bill. television! master date on coupon. Ira - can earn extra start you Leonid C. lane President the very -TV Almost irom radio RADIO.TELFVISION TRAINING ASSOCIATION 4 by repairing 19th Street, Now York D, New York while learning of my De/31 ER, 52 lose Many ' 1001, FREE SAMPLE money yh repa Moll me year NEW FREE and Dear M. Lane. for me hay I can mete 114 sets for ... pay LESSON, and FREE aids Thor will Phew , week ne obligation and I understand I am under earn Dp earnings MONET IN TELEVISION students time no salesmen will eon from spare C Telephone Tronenitter training I PLEASE PRINT PLAINLY, their entire service business. own profitable their Name . start

Address will call No salesman City Zone STOIC --IN: I AM INTERESTED VETERANS! RadienFMTY Terhnirian (curse Write discharge date R (Jiff la gitiv-iaian. ©naimim A Autiatten , FM.19 Technician (ourse r] TV Cameraman 1 Srad.a (ar"e 52 EAST 19th STREET NEW YORK 3, N. Y. re,m..a^ Licensed by the State of New York Approved for Veteran Training L. 7 August, 1955

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k' TUBE TESTER WITHIN the next two months, a "survey" will be made of the readership of "POP'tronics." Its purpose will be to s determine individual reader preferences among the articles that have been published in our magazine, and to find out what readers would like to see in future issues. Obviously, in a magazine whose distribution is in excess of 300,000, this poses quite a problem; but to those who may receive these survey inquiries, may we stress that all answers are important. In fact, your one vote in any direction pro or con your favorite topic or pet peeve may influence editorial judgment. Careful consideration should be given all the questions of the survey; whenever possible, take into account the opinions of your friends and associates. Thoughtful opinions with solid backgrounds will permit a speed- New EMC Model 208* CHECK THIS EXCLUSIVE ier analysis COMBINATION OF and a quick application of the Fd.Fa.A,E tests all PEATURES: ideas found to be most desirable. tube types quickly ... Lowest market price Completely portable The Editors are always interested in read- easily ... accurately Checks ell popular octal, ... in the field or !octal, iniature and nova) er letters and comments, whatever the shop. base tubes sub- Flexible switching ject. Among our audience, The system there will be many sensational new EMC assures complete testing who will recall Model 208* gives you of all present and future writing to us some months tubes types ago for for the first time a Elements numbered accord- specific articles -which may now complete precision tube ing to RTMA base system be included in this very issue. Individual sockets for each Articles such tester for less tube type as the "Electronic Whistler" (page 57) and than $25.00. Checks completely for quality as well as shorts leak- "Build Your Own Applause Meter" (page ages, filament continuity With it you can quickly or opens between any two 47) were originally requested by readers and accurately test tube elements Visual line voltage check and designed according to their specifica- all tube types with adjustable control as- tions. for quality sures accurate quality Forthcoming articles on transis- as well testing tors, printed as shorts, leakages, Matches and checks HI -Fi circuits, ham radio receivers tubes such as 1614, KT 66, filament continuity and 5881 and transmitters will all be derived from and opens. Space saving, high Impact reader requests. May we have case, 51/4 x 63 x 23/4" yours? MODEL 208 TUBE TESTER Comes complete with de. In general, reader interest can be ranked (COMPLETELY WIRED AND TESTED) tailed Instruction book and Only $24.90 tube listings in the following subject order : high fidelity MODEL CRA (PICTURE TUBE An Invaluable tool far: Service- ADAPTOR OF MODEL 208) $4.50 (leading subject by a wide margin), men, radia hams 111-F1 fans, ham students, hobbyists. or novice radio, electronic gadgetry (such welt. 1. Dope, PF.5 Godoy fw ampl.fe catalog as the "Theremin," of precia(on ene egalpm.ae. - - Geiger counters, SVPOST DEPT. "Whistler," etc., but now leaning towards ,6 ELECTRONIC r MEASUREMENTS small computers and games), R /C, basic CORPORATION electronic instruction and experiments, and 370 BROADWAY finally, SWL. This list NEW YORK 13, N. Y. excludes general interest topics which appear to have a widespread appeal. o.p.f. POPULAR ELECTRONICS

AmericanRadioHistory.Com II1IL1 o 20 e If you believe that you have an invention, you should find out how to protect it. The first step is to have a search made of the prior pertinent U. S. patents. If a report on this search indicates that the invention appears patentable you can apply for a patent, and the specifications and claims should be prepared.

The firm of McMorrow, Berman & Davidson, with offices in Wash- ington, D. C., is qualified to take the necessary steps for you. We can make a preliminary search on your invention, advise you whether we think it can be patented, and prepare your application for patent.

Unless you are fully familiar with the U. S. Patent Laws, we recommend that you engage the services of a Registered Patent Attorney to protect your interests. The patent laws are your laws. A patent gives you the right to prevent others from making, using or selling the invention claimed in your patent for a period of 17 years.

Use these patent laws for your protection. Investigate whether your invention can be patented. If you have what you believe to be an invention, we suggest that you have this firm make a search for you.

Send for a copy of our Patent Booklet entitled °N., "How To Protect Your Invention," containing information about patent protection and patent procedure. Along with this we will also send you an "Invention Record" form, for your use in writing down and sketching details of your invention. We will mail them promptly. No obligation. They are yours for the asking.

McMORROW, BERMAN & DAVIDSON Registered Potent Attorneys PATENTS COPYRIGHTS PATENTS 349 -B VICTOR BUILDING, WASHINGTON 1, D. C.

August, 1955 9

AmericanRadioHistory.Com Long- Play(331 RPM)Hi- Fidelity A-LL LETTERS GREAT r- INFO ON CARDIOLOGY NEEDED I was quite interested in the short article on cardiology (April issue), and should like to know Oong the address of the National Heart Institute.. . JAZ I am CLASSICS gathering information on electrocardio- :lama graphs for a thesis I am writing. Any information will be gratefully accepted. DAVID L. BLAIR Kingston, Ontario A Treasury of Jazz FEATURING Tite National Heart Institute is located at 9000 Wisconsin Ave., Bethesda, Md. Readers Charlie Parker who may have additional information for Mr. Blair can Teddy Wilson reach him at 26 Nelson St., Kingston, Ontario, Coleman Hawkins Canada. Eddie Condon Not $1 Each Dizzy Gillespie - But $1 for ALL Jack Teagarden TEN PHONO TRANSMITTER Pee Wee Russell YES, you get ALL TEN of these "all -time great" Please send me plans for a phonograph record Erroll Garner jazz transmitter or tell me where I can get such plans. Sidney masterpieces for just Bechet $1.00, no strings attached! DALE CITRON Art Tatum We make this amazing of- Chillicothe, Mo. fer AND DOZENS OF to show you the qual- OTHER "GREATS "! ity of these Jazztone So- A suitable unit is described fully in our March, ciety recordings, obtain- 1955, issue ( "A Modern Wireless Record Player," Playing able nowhere else! Every pages 49 -52). In addition, Jelly details on a "Home Roll Blues jazz era, every jazz style, Broadcaster" were given in Honeysuckle Rose virtually our November, 1954, the whole his- issue. To obtain Basin St. Blues tory of jazz can be traced back copies, send 30 cents for Relaxin' at in the wide range of these each issue desired to our Circulation Department, Camarillo, etc. selections But on ly bby 64 East Lake St., Chicago 1, Ill. hearing, these dazzling recorded performances can technical and artistic excellence retheir twonderful ELECTRONIC "DREAM FARM" high fidelity. Your article in the March issue on "Electronic How the Jazztone Society Operates Miracles of the Future" was all right, but it You are not obligated ever didn't have from to buy another record anything on farming by push button. us. You do have the right to try any of the So- My dream farm includes ciety's monthly selections you wish. You receive prior a tractor equipped with notice of these and pay nothing in advance. Those power steering, a truck tractor with hydramatic you want are sent to you for FREE trial. After 5 drive and high power generator the records you decide days, which could be to keep are billed you at the run from the power take -off. This would special Members' low price of just $2.75, plus a few be used cents shipping, for each 12 -inch long -playing record to power a radio -control receiver. Also, there (average playing time one full hour). You save would be a television transmitter 40% of the usual over for sending pic- retail price! Start your jazz library ture signals to a receiver with these 10 classics for only $1.00. Mail coupon in an air -conditioned with a dollar now while supply lasts! Money -back room where the R/C transmitter, controls, and guarantee. operator would all be located. I read the other day that two TV hams were THE JAZZTONE SOCIETY, INC., Dept. PE-8 using oscilloscope tubes for camera tubes. Or an 43 West 61st Street, New York 23, N. Y. RCA Enclosed camera tube could be used to see everything is $1 in full payment for the recordings from the tractor of 10 jazz classics listed. Enroll me as a Trial seat that an operator on the Member. Privileges: No purchase obligation ever! tractor would normally see, and to send the Advance notice of releases. 5 -day free trial on any picture signals -via the TV transmitter dics. I may reject records before or after receipt; on the may cancel membership at any time. For future tractor -to the receiver. l.p. discs I keep, I'll pay only $2.75 each, plus About a 3- or 4- channel R/C unit would ping saving ship- do- ... 40% off usual retail price! one channel for steering, another for throttle, one for the power -lift, and one for the setting of the Name automatic transmission; also one for the starter. I forgot to mention that two or three camera Address tubes would be needed to see in front and behind and wherever the operator might need to look. City Zone.... State How's that for dreaming? Canada address: 105 Bond St., Toronto 2, Ont Incidentally, why aren't the majority of R/C LIMIT: One sample package per customer. fans using more powerful transmitters? I L (Continued on page 14) IO POPULAR ELECTRONICS

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\\ HY hasn't somebody done ÈIEVISI0 this BEFORE? That's what you'll exclaim the minute you start browsing through this amazing new one -volume in- AND RADIO struction manual in TV and radio repair. For here at last a well -known ENURING EXPERT has found a way to tell you in PLAIN ENGLISH how to fix almost ANY radio or TRY IT television set. (And he even tells you where you can go to have the extra -tough jobs done Save Money on Your Own Set FOR you . . at reduced pro- year lust in instal link:. save $50 to $100 set. REE rates.) Right from the repairing servicingis controls' fessional to adjust SET very first chapters you can start tubes to replace if picture is entirely dark blurred split - distorted - off center - OWN doing simple repairs ... and be- tilted-- wiggles- and weaves-too pale -too ON YOUR black litters - snow effects - drifts - etc.. fore you're HALF way through etc. - 10 DAYS the manual, you can fix HALF FOR the television and radio sets show you exactly WHAT and a HOW to fix, step -by -step. that you encounter. In just The author is Associate Editor of few weeks you can start fixing Electronics Magazine. He Spent PARTIAL CONTENTS your own and friends' sets .. . FOUR years making this one -vol- How to Remove and Replace Tubes get a service shop job ... even ume manual practical and easy - Testing Tubes without a Tester money- making to- understand -even for an "un- Using a Table Tester Power start your own Supply Troubles How to Test business at home. handy" beginner. and Replace Resistors, Controls, Here's everything you need to Switches. Condensers, Coils, know about where and how to buy Transformers Loudspeakers Why It's So EASY to Understand tubes and parts, where and how to Phono Pickups and Needles An- You get no complicated formu- get an official circuit diagram for tennas . . . MUCH MORE. las, algebra, laboratory experi- any receiver; how to choose and ; to test tubes ments. Instead you deal only with use basic tools how \l'ritlen as simply and clearly as pos. ; to the parts that go wrong in sets - WITHOUT a tube tester how siblc. :\ nalw'al for the & TV News the trouble 58 TV controls ; how how to recognize -and use common "Prepared for people who know ebso what to do about it. "Easy as to "diagnose" and "cure" common lately nothing about radio or use of ; fix A -B -C" directions and 700 clear radio and TV troubles how to tools. -Radio Electronics photos, diagrams, and drawings loudspeakers, phono pickups ; how "Unique in Its ability to explain servic- check ing in easyto- understand ter to install and r cs. South antennas ; and much, much more. 9 Tells HOW To "Cash In" r BIG DEMAND FREE 10 -DAY TRIAL COUPON ON THE SEND NO MONEY FOR RADIO-TV REPAIRMEN McGraw -Hill Book Co., Inc., Dept. PEL -8 Over 25 million TV sets . I.:xamine this hook 327 West 41st St., New York 36, N. Y. 10 over 100 million radios' Make for days BEFORE Please send EXAMINATION. Radio ' nice extra money just fixing you decide if you wish OM' v,lumee ' Televlisio,I and Repairing. it out I, ob,, Markus. if not delighted. I may return book. sets for friends and neighbors to own it. Try I will send only $1.95 plus own pay nothing. Otherwise. of in your spare time . . . or start FREE on your few nis delivery; then ii monthly installments your own full -time repair busi- or a neighbor's set. $2.f' each. ness. Book tells exact- See how simple and Nanne ly how to get started : easy it makes nearly which tubes to stock every repair job. how to make a serv- Make it pay for itself Address 10 or don't Zone... State ice call. Actually start in days City PELS fixing sets and mak- keep it ! Mail coupon : McGraw -Hill Book ing money before to SAVE MONEY. Check here If enclosing full price of you're half -way Co., Inc., Dept. PEL -8, $7.55 ,uilh coupon. Then WE will pay for delivery. Same through book. 327 West 41st St., New 10 -day return privilege. (Offer good in U.S.A. ovl =.1 York 36, N. Y. L August, 1955 1

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AmericanRadioHistory.Com Letters from Our Readers Build the instruments (Continued from page 10) the professionals specify... wouldn't dream of using less than 50 watts. And 1000 watts would be better. BUILD EICO KITS -SAVE 50% CHARLES R. NICHOLS Como, Texas

There is certainly food for thought in your suggestions, Mr. Nichols. Regarding the power used on R/C equipment, however, FCC regulations provide that non- licensed R/C operators may use R/C equipment that has a maximum 1 power input of five watts to the final stage for crystal- controlled transmitters used on 27.255 mc. Ten watts is permitted on the 460 -468 mc. band. Equipment used on the ham bands is restricted by ham standards, but higher maximum powers are permitted. For model control, of course, you need power to control only as far as you can see, so why use more when a little will do?

HI -FI INFORMATION I have recently become interested in hi -fi systems. In Vacuum Tube EICO VTVMs searching for information so that I may Voltmeter in use in labs best determine what I like and can afford, I find of Stromberg- that most available data is highly technical and KIT $25.95 Carlson, complicated. Wired $39.95 Roches-er, N.Y. Can you mention sources from which a very "green" novice can gain basic information? Í imagine what I am searching for could be re- ferred to as a "Hi -Fi Primer." EICO test instrument kits are K. I. TRENER complete and professional from Phoenix, Arizona circuitry to front panel -are utilized by TV leaders like All the information that we have published thus Stromberg- Carlson, CBS-Col- far, as well as scads of information to be pub- umbia, Emerson, etc., leading lished in the future, is directed toward satisfying electronic schools and univer- the need you mention. In addition, there are several sities, excellent books on the and over 60,000 radio - 5" Push Pull subject of hi -fi which have electronic servicemen coast to been published recently. A few of these have been Oscilloscope reviewed coast. Kit $44.95 in POPULAR ELECTRONICS and many more will be discussed in future Exclusive Wired $79.95 issues. Offhand, a few "Beginner - Tested" representative titles come to mind: "High step -by -step instructions Fidelity make Home Music Systems" by William it easy, educational R. Wellman, and en- published by D. Van Nostrand Co., New joyable to build EICO York, Kits. N. Y.; "Home Music Systems" by Edward Tatnall Only basic tools, no electronics Canby, published knowledge by Harper Brothers, New York, required. You build N, Y.; and "The New High Fidelity Handbook" 'em in one evening -they last by Irving Greene and James Radcliffe, published a lifetime. Exclusive 5 -way by Crown Publishers, New York, N. Y. Guarantee on instructions, 6V & 12V Battery components, performance, life- Eliminator & Charger time service and calibration. KIT $29.95 SUBSTITUTE FOR RUBBER GROMMET No wonder there are over t/2- Wired $38.95 million in use the world over! The other night I was putting a new line cord on my short -wave receiver, and I was at a loss as to 42 models to choose from. what to do for a rubber grommet to lead r- the There is an EICO Distributor cord out through the chassis. I didn't want to wait in your neighborhood. Write until the next day to put one on, so I hunted around the house for his address as FREE for something to use, and came CATALOG PE -8. across a "Spoolie" hair curler. It looked good and served the purpose. Prices 5% higher 1,000 Ohms /Volt DICK SIMKINS on West Coast ©55 Multimeter Sepulveda, Calif. KIT $12.90 Wired $14.90 CONVERTING 78 PHONO 84 Withers Street LiE/COQ After reading Brooklyn 11, N. Y. Arthur Trauffer's piece on "Con- verting Your 78 Phono to LP," (May issue), I agree with him that 78's are getting to be out - 14 POPULAR ELECTRONICS

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15 Augus+, 1955

AmericanRadioHistory.Com moded. I am particularly interested in a 78 phono bottom of one side and in either direction, de- in which the record turntable itself is spun around pending by the motor. on the tape recorder used, but I don't This is not the same as the one know about recording described in Mr. Trauffer's on both sides of the tape. article. How can I cut Can you clear this up? the 78 -rpm speed down to 45 rpm on mine? WILLIAM Also, Mr. Trauffer did not mention how C. MADISON the New York, N. Y. pickup arm is supposed to fall on a 45 -rpm record which is only 7" in diameter. The 78 -rpm record As far as we know, there is no tape-recording may be 10" or 12" in diameter. What changes unit that will record on both sides of the sanie could be made in this respect? tape. The possibility of bleed through the tape is STAN too high for this GRYGATIS type of operation. tf Troy, N. Y. The phono unit described by Mr. Trauffer used SURPLUS SET CONVERSION a shaft which rotated against an idler was wheel. It have only by changing the diameter of I an Army surplus tuning unit, Model BC that this shaft 746 -B, the speed of the phono could be altered. In 3825 kc., and would like to know if there the case of a unit such as is any way I can connect this to a Zenith AM- you describe, which is FM apparently a direct -drive system, the receiver. If there is no way, can you tell me to change only way how I can put the speed is to change the motor itself. this unit to use? In any event, when the phono has JACK M. WILLIAMS verted from been con- 78 to 45 rpm, the arm must be placed Misenheimer, N. C. on a 45 -rpm record manually. It is difficult for us to visualize the purpose of connecting the BC -746 -B to your AM -FM radio. Almost all war surplus radio QUERY ON THEREMIN and electronic equipment now on the market is highly specialized and I we sincerely am writing to inquire if you have ever in doubt the value of buying "bargain" the past published a schematic for units that are impossible to convert to a the construction application. useful of a theremin? If not, could you supply the me with address of R. A. Moog Co., which I believe manufactures a theremin commercially? CAREERS R. A. AUSTIN, JR. IN ELECTRONICS New York, N. Y. I have noticed that many of your readers are interested in a course in electronics. In our April issue, the lead I am, too. article contained Could you run articles explaining the various complete instructions and plans for building own theremin. your courses available from the mail order schools? A copy of this issue may be ob- Costs could be discussed tained by sending 30 along with the subjects cents to our Circulation covered, etc. Another question I have Department at 64 E. Lake St., Chicago is theremin 1, Ill. The what does the title "Electronic Engineer" en- manfactured by R. A. Moog described Co. was compass? in the January, 1954, issue of our sister H. EUGENE HARDY publication, RADIO & TELEVISION dress NEWS; the ad- South Gate, Calif. of this organization is 51 -09 Parsons Blvd., Flushing 55, N. Y. See our article entitled "Planning To Be An Electronic Engineer" which appeared in the June issue, and watch for future articles covering the TRANSISTORS IN R/C RECEIVER training of electronic technicians. Would it be possible to make a transistor -powered R/C receiver? If so, will you please publish R/C BOATS a diagram in a future issue. LUCIAN DREOSSI With reference to the article in your May issue Oshawa, Ontario, Canada entitled "The Boom In R/C Boats," I am interested in obtaining the name and address of the A forthcoming or a two- manufacturer of the "Chris Craft Corvette." stageR /C rceiverrusing altransistorrinfone RICHARD The stage. A. STRAUSS set will not use transistors in both stages Detroit, Mich. because it is difficult to obtain a transistor which This will operate as amplifier and detector model is made by Sterling Models, 1530 -34 Most at 27 mc. N. Hancock transistors operate only in the audio range St., Philadelphia, Pa. and slightly above.

POCKET TAPE RECORDER TAPE RECORDING With reference to the pocket tape recorder de- It was a pleasure to scribed in your April issue, how is playback ac- read your May issue, es- complished? pecially the two articles on "Tape Types and Timing" and "Tape Recorders." They were very R. L. ANTHONY timely for me, as I plan to buy a tape recorder. Hyde Park, N. Y. I have heard someone mention a tape recorder Recorded material from the "Midgetape" that would record on both sides of may the tape. I be heard through an earphone or any external understand that you can record on the top and amplifier. An accessory amplifier with a 2" 16 POPULAR ELECTRONICS

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in listening LICENSING OF AMATEURS I would appreciate it very much if you could supply pleasure! me with any information which might be helpful in obtaining an amateur license. ARTHUR R. HALL New York, N. Y. In this issue of POPULAR ELECTRONICS, we are introducing a column by Herb Brier entitled "The Transmitting Tower." You will probably find the answers to most of your questions in this column, which appears on page 68. For additional information, we suggest that you write to the American Radio Relay League, West Hartford 7, Conn.

ELECTRON MICROSCOPE Concerning your article on the electron microscope (May, 1955), how much of the magnetic lens system is enclosed in a vacuum? What other parts are enclosed in a vacuum, and how is the object inserted into the electron beam? Can you furnish me with additional information or the source of such information on this device? DON ADAMS Sigourney, Iowa Aside from the information contained in the bor the realism article as it appears in our May issue, we have of concert - no additional hall performance data on this subject. It is possible in your home that further information can be obtained from The Mr. Ken Kilbon, RCA Laboratories, Princeton, "MUSIC LOVERS" Cartridge N. J. is a new, 3- speed, dual needle ceramic cartridge, designed to enhance the quality of all the popular CITIZEN'S BAND high fidelity equipment in use to- I would like day. Feeds to know if it is permissible to be directly into magnetic a holder of a or ceramic citizen's band license and an ama- inputs, allowing the teur's license at the same time. Also, you full advantages made of compensation a mistake in your article on the "Lorenz 61." You circuits. said on the license -free band of 27.255 5liminates me . .. ". A license is necessary, although you do Has higher not have to take induced hum output an examination to get it. Eliminates Response not MELVIN STEWART "drag" caused affected by load Pensacola, Fla. by magnetic resistance There is no such thing attraction as a citizen's band li- to 10- second needle cense. Anybody can use the citizen's steel turntables band, pro- replacement vided that the equipment used is licensed. Increases record Neces- Individual needle sary forms may be obtained from the FCC. and needle life compliance FREE Comparative analysis booklet on the "Music Lovers" Cartridge AUDIO AND HI -FI SECTION How about combining all the material SHURE on audio BROTHERS, INC. and hi -fi into one big section in each issue of 225 W. HURON ST. CHICAGO 10, ILLINOIS the magazine? I realize that this will mean more editorial headaches, Please send analysis booklet on but it will certainly prove a your "MUSIC convenience for readers who are hungry for news LOVERS" cartridge and technical info on hi -fi. NAME KENNETH D. SHAY Denver, Colo. AUDRLSS In response to this and similar requests, we (I 11- 70 ....ST .i FE are doing exactly as suggested, starting with this issìce. - 18 POPULAR ELECTRONICS

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August, 1955 19

AmericanRadioHistory.Com A PRIMER ON CAPACITOR~ T T T T T T T T T T TTT T J_ How a Capacitor Works 1 (Continued from the April issue) Far too many beginners in electronics forget that in the final analysis there is no 1 such thing as a "fixed capacitor." The term is only relative as many a circuit de-1 signer chasing "bugs" has discovered to his sorrow. The capacitance value stamped on a capacitor is only a nominal value. This is T usually the specified value at the standard measurement temperature of 25 °C (77F). _L Sometimes as in the case of ceramic capacitors it may be the minimum acceptable 1 Tvalue at this temperature. Sometimes a tolerance on the capacitance value at this temperature is stamped on T a capacitor; sometimes it is not. The term "tolerance" means simply that the capacitor must be within the specified percentage of its nominal value at the specified reference temperature. For example, when paper tubular capacitors are not otherwise marked or color T 1 coded, the customary manufacturer's capacitance tolerances by RETMA standards for values up to .0019 µF is 1 T -25 %, +60 %; from .002 to .009 µF, -20 %, +40' ; : from .01 to .09 µF, ± 20 %; from .1 to 1.0µF, , -10%, +20 %, and above 1µF ± 10 . T This means that a capacitor marked .005 µF for example, will actually measure 1 anywhere from .004 to .007 at 25 °C (77F). 1 Now let's look at this capacitor when it is heated up to 85 °C (185F) in a television set. If it is impregnated with stabilized wax, it will drop by about 8% in 1 capacitance from its original room temperature value. On the other hand, if it is l impregnated with mineral oil, its capacitance may increase by about 2 %. If it is impregnated with a typical polyester material as in many types of solid -dielectric paper tubulars, it will increase by about 9 %. If it is impregnated with Sprague's -1- new HCX hydrocarbon impregnant, the result will be a far more stable, solid- 1 T dielectric capacitor which will increase in capacitance by about only 1% as a result of this rise in temperature. T The changes in capacitance quoted are typical for the material mentioned. Some production units will have slightly less change in capacitance while others, of 1 course, will have slightly more. Capacitors made with plastic dielectric films will also change in value as the temperature shifts up and down, the amount depending T I on the particular plastic film and impregnant used. 1 This may help explain to you why one paper capacitor will work perfectly well in a circuit while another will not, even though both "look alike." T Getting back to the subject of capacitance tolerance, let's look at dry electrolytic capacitors. Here the permissible deviation at room temperature from the stamped 1 Tvalue is even wider. General industry practice on aluminum electrolytics permits a tolerance of -15 %, + 250% at rated voltages up to 50 volts d -c; of -10 %, 4- 100 ó at 1 voltages from 51 to 350 volts; and of -10%, + 50% at rated working voltages of 351 to 500 volts d -c. And electrolytic capacitors too, change in capacitance value with change in temperature. Furthermore, differences in electrolyte and paper spacers will give different answers for two capacitors of the same voltage rating of 1 the same manufacture made to two different performance specifications. 1 Let's take a typical 40 µF 150 volt d -c capacitor. It may actually measure 45 µF at room temperature, and will measure 40 µF at freezing (0 °C or +32F). It may increase to 49 µF when the set is heated up to +85 °C (185F). As the equipment in 1 which it is used grows older, its capacitance value will decrease with age and ma} be down about 10% after three or four years of use. T -To be continued in October issue - 1111 This informative message is No. 5 of a Series contributed by 1 1 1 1 Sprague, the world's largest manufacturer of capacitors. ITTT TTTT Write Sprague Products Co., N. Adams, Mau., for complete Sprague catalog.

20 POPULAR ELECTRONICS

AmericanRadioHistory.Com By E. G. LOUIS feuc

MAGINE a giant factory occupying many Electronics leads the wa y as city blocks. Raw materials - plastics, man enamels, steel, and copper -move in a enters a new era of industrial steady stream through the entrance. Fin- ished products -radio and television receiv- progress -the age of automation ers, washers, ironers, and other appliances -roll out at the other end of the factory. The time is 1955. Employment: 12,000 use the muscles of domesticated animals. workers, operating on a single 8 -hour shift, Still later, man learned to utilize water five -day week. power. Finally, steam and electricity began Let's take a small step into the future. to take the place of human and animal Again, imagine a vast factory covering power. many city blocks. Raw materials move into Although these changes in production the entrance in a steady flow; finished con- techniques took place over a period of sumer products stream from the exit. Pro- many years and, for that matter, are still duction capacity is tremendous, five to ten taking place in remote corners of the times that of the former factory. The time world, their impact on man's productivity is 1975. Employment: 12 workers, operat- and on his standard of living was so great ing in three shifts. The factory, however, that they have represented an "Industrial operates 24 hours a day, seven days a week. Revolution." Another Industrial Revolu- Impossible ? Not in the least -it's almost tion is now taking place. Like the first here. one, the changes it brings will probably In the middle of the 18th century, the occur over a period of years rather than slow changes in the way man manufac- overnight. And, like the first one, the new tured his goods -which had been evolving Industrial Revolution is likely to bring for years-took on definite shape and vast increases in man's productivity and in form. These changes accelerated until by his standard of living. the middle of the 19th century almost all Just as the first Industrial Revolution the major producers of manufactured substituted mechanical power for human goods had completely altered their meth- muscle, the second Industrial Revolution ods. The 'alteration was a simple and is the substitution of automatic controls logical one -the substitution of mechan- and electronic "brains" for human brains ical power for human muscle. in the performance of routine activities. Of course, mechanical power had been Let us imagine how an automatic fac- used before, but not to so large an extent. tory might evolve in the manufacture of Much earlier, man had relied on his mus- a simple product like a metal disc.' cles alone, aided by the few simple tools he First, going back to before the days of could produce. Later, he had learned to chemical and mechanical power, we find

August, 1955 21

AmericanRadioHistory.Com Vital decisions to production problems can be made accurately and promptly with Panellit information system. that a man might produce a metal disc by comes down. So, for safety's sake, the ma- using a simple punch, a die, and a hammer. chine is operated considerably slower than The punch, die, and hammer are all pro- its maximum rate. But -as electronic con- duced laboriously by hand. He places a trols are developed, man soon learns to sheet of metal over the die, sets the punch protect himself. By placing a source of in position, anti strikes repeated blows until light on one side of the punch press and a the disc is punched out. Since he can photoelectric relay on the other, he can add deliver only a limited amount of power a safety control which prevents the opera- with each hammer stroke, several strokes tion of the machine if his hands are in the are necessary to punch out the disc. Pro- way. He now operates the machine at a duction is not very fast-perhaps one disc faster rate and produces thousands of discs per minute. per minute. Realizing that greater production would Logically, the next step is to provide be possible if he could punch out a disc mechanical hands which feed the metal with every stroke, the man uses a heavy plates into position automatically as the weight in place of the light hammer and punch moves up. With this arrangement, sets up a jig so that a horse or mule walk- the operating speed of the machine is in- ing on a treadmill will alternately lift creased still further, for mechanical hands and drop the weight. He increases produc- move more rapidly than human hands. tion by several hundred per cent, and now Since little time is required to load the produces several discs per minute. feed rack, one man can operate several When steam, water power, and electricity machines and can now produce tens of become available, man recognizes that he thousands of discs per minute. now has sufficient power to punch out a Having gone this far, it is a compara- number of discs with a single stroke if he tively simple matter to add a conveyor belt uses a multiple punch and die. After set- and additional automatic machines to feed ting up the machine, he need only feed in the metal plates from a vast stockpile of large sheets of metal and each stroke of the raw material to the feed racks of individ- punch press produces dozens, or even hun- ual punch presses. Since the man no longer dreds, of discs. Production again increases, and a single man now produces hundreds of Micromatic "robot" hones gears auto- discs per minute. matically. It stores prefabricated parts However, a large punch press is a dan- and feeds them to honer (1). Parts are gerous machine. If the man operating it gauged (2). Result is checked by control doesn't move his hands quickly enough, he unit (3) and shown on signal panel (4). could be seriously injured when the punch Gates (5) pass parts to containers. 22 POPULAR ELECTRONICS

AmericanRadioHistory.Com tk? has to load the feed racks of individual machines, he can operate a great battery of punch presses -and one man now produces hundreds of thousands, or even millions, of discs per minute! And a simple type of automatic factory has been evolved! However, the automatic factory of the future will not be quite so simple. Instead, a group of machines producing a single part, such as the metal disc, will be only a small part of the entire factory. In an automobile factory, for example, automatic machines will turn out complete engines, working from basic raw materials and metal ingots. Other automatic machines will mount these engines in chassis which, in turn, have been assembled by still other automatic machines. It is possible to build Cartoon of microhoning machine depicts its a complete factory for the automatic as- mcny automatic and simultaneous operations. sembly of a television receiver, an electric range, a refrigerator, or any similar item. Machines will carry out test and inspection

Lo =

August, 1955 23

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operations as well as assembly, insuring Look underneath the chassis of an older high quality products. Only a few human television receiver. You'll see a "rat's nest" "supervisors" will be required, and their of wires and parts. But even such com- function will be merely to oversee the plicated devices as television receivers may operation, to make repairs if a machine be turned out in a matter of seconds by should break down, and to insure that no means of automatic machinery. Printed interruptions occur in the smooth flow of circuit techniques are used. The entire cir- production. cuit is reduced to a simple drawing that If the rejection rate should be high in can be reproduced on a metalized plastic an automatic factory, it would indicate that plate by a photo- etching process. These some part of the factory was not function- boards are then passed down an assembly ing properly. In such a case, the electronic line where automatic robot machinery in- "inspector" would order an automatic test serts resistors, capacitors, and other corn - of machines in the production line. The ponents in their proper positions in the faulty machine, once located, would be circuit. The entire chassis board is soldered switched out of the production line auto- in a single dipping operation. matically and a spare unit operated in its The National Bureau of Standards, place until the human "supervisors" could working under the code name of "Project repair the defective "worker." Tinkertoy," has developed still another of Fields Application technique for the automatic production of electronic equipment. Individual electronic Even precision machine work may be circuits are built up from small ceramic carried out by automatic machinery. One cells. These may be manufactured, checked, company has developed a milling machine and assembled into electronic circuits in a with an electronic "brain" consisting of a continuous flow by automatic machinery. tape recorder and electronic controls. To The completed circuits may be tested auto- set up this machine for operation, a highly matically, with defective units thrown skilled, precision machinist first guides the aside. Only a few changes in the machinery milling machine to produce a single part. are necessary to switch over from pro- While he does this, all movements of the ducing radio or television receivers for machine are accurately recorded on tape. civilian consumption to manufacturing Finally, the machine is used to turn out complex radar equipment and specialized exact duplicates of the original part auto- military gear for national defense. matically by playing the tape over and Automatic equipment may be used for over. It is possible to adapt lathes, shapers, testing and inspecting all types of man- and other machine tools to operate with ufactured articles, from checking the color tape recorder "machinists." on a painted toy to the weight and contents Chemical plants and refineries are espe- of canned goods, from inspecting bottles of cially well suited to automatic production. liquid for foreign matter to the accuracy of The flow of chemicals through pipes can precision machine parts, from the thick- be controlled easily by valves. Mixing, heat- ness of metal plating to the operation of ing, and other processes are easily carried a complete engine. In some cases, auto- out using automatic and remote controls. matic machinery may be used for making A single operator may "supervise" a large simple repairs. chemical plant by means of push buttons and knobs, keeping a close check on pro- Effect on Future of Mankind duction with his hundreds of meters and Of course, such a radical change in pro- gauges. Automatic operation is especially duction is bound to have a great effect on desirable where dangerous materials are mankind. It will mean the availability of a handled as well as explosives, acids, poison- greater variety of products of consistently ous gases, and radioactive substances. high quality, more leisure time for individuals, and a greater variety of jobs. Differ- ences between "unskilled," "semi- skilled" STOP NAD -TOOL ADJUST and "skilled" workers will disappear be- +TOOL ADJUST cause most factory workers will be skilled .:O technicians, enjoying good wages, interesting work, and short hours. FEEDING SEOREGATWG There will be a demand for highly skilled machinists and precision workers to make - WARN I +WARN -REJECT a O+REJECT "master" tapes for the control of machine aK- r-PART 1 tools. More engineers will be needed to design and to build automatic machinery. will Diagram of basic -post- process control." And there be a great demand for tech- Machine will be stopped automatically nicians and operators to "supervise" and to if tools tail or if tolerances are violated. maintain the automatic factories. 24 POPULAR ELECTRONICS

AmericanRadioHistory.Com Automatic alurninfaii of TV picture tubes et RCA plant using Stokes automation. Close -up at right slows how fixed ramps en -he track trp vcrics_s levers. This action oontrols the ope:ati3a of other machines.

While there may be some temporary un- employment in a f.w ir_d istries, this will soon be taken up by the _r :rease in production and the new industries which will spring up. For, just as the first Industrial Revolut:or_ caused a tenporary loss of employment in one or two industries, it eventuaJy resulted in a higher over -all standard of living for mankind, in more employment, and in more leisure for the average Man. And the second Industrial Revolution, tike the first one, will not happen overnight-it will Le spread over many years, with the newer in :°ustries, employing rela-ively few workers, changing over first. With sutcmatic factnrirs and machines having such a tremendous impact on human activity, yoi would expect a new term to describe this 3e3í. There is one. Watch for .t; you'll se' it often in the future: Automation!

August, 1955 7 5

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ACCURACY AND SPEED are features of the Morse Code Converter "Trak" code converter, the first successful operating instrument that can convert Morse code signals either from the air or perforated tape, and translate them automatically into a printed message on a standard teletypewriter printer. An all- electronic converter, the device accepts signals from a radio receiver at any 1 speed from 10 to 600 words per minute. It then translates the signals into suitable electric pulses for a standard teleprinter which prints the message text. The converter works equally well on signals produced by hand or machine keying. It also will scan undulated inked tape by means of a sweep scanner. Similarly, its output can operate reperforator equipment or key land -line loops to remote teleprinter units. "Trak" instantly adjusts to different speeds of code transmission, automatically compensating for changes of pace. Special memory circuits permit it to "copy behind" in the same way as a human operator would. The development of the device was largely the work of William Reid- Smith- Vaniz, Jr. (shown in photo) of C. G. S. Laboratories, Inc., Stamford, Conn. -0-

Unique Features, Advanced Design in Hi -Fi Units

INTENDED FOR CUSTOM HI -FI installations Also included are separate bass and are the A -440A preamplifier -equalizer and treble controls, and provision for changing the A-340A power amplifier, introduced from 'volume" to "loudness" control. Fre- by Altec Lansing Cdrp. Although the two units are designed to be used together, they may be interchanged with similar units of comparable quality for satisfactory results. The A -440A features a hinged door that hides all controls except the "on -off" volume knob. With the door open, all controls are accessible. On the inside of the door are printed instructions for selecting record equalization settings, of which 25 are available. Another facility allows any input circuit to provide programing for tape recording while monitoring from the tape playback head; this permits listening to a program on tape while it is still being recorded. The unit is self -powered, and each quency response is reported as 5 to 100,000 of five inputs has its own level control. cycles ± 1 db. Net price is $139.00. The A -340A power amplifier features a newly developed output circuit that uses type 6550 power tubes. These tubes, which have a capacity of 100 watts, do not require balancing. They enable the A -340A to deliver 35 watts with less than 0.5% distortion. Frequency response is said to be 5 to 100,000 cycles ± 1 db. Net price is $159.00. For more data, write to manufacturer at 161 Sixth Ave., New York 13, N. Y. -®-

26 POPULAR ELECTRONICS

AmericanRadioHistory.Com ELECTRONIC FISH -FINDERS A

-s

Ultrasonic beams penetrate ocean depths; their echo signals provide valuable data on fish and other undersea objects

FISH may travel in schools but they are Captain Henry Rollins of the "Malolo " - not learning enough to beat new elec- out of Newport News, Va.- commenting tronic devices that locate them silently and on the Edo "Fishscope," reports: "On my accurately. Electronic "fish- finders" -once first trip with the 'Fishscope'-the first an experimental novelty -are now being in our area -we had made a set and were used widely by commercial fishermen to dragging down with the rest of the fleet. great advantage. Many leading manufac- The scope showed a real good concentra- turers, in response to increased demand, tion of fish, but after ten minutes it dis- are producing and promoting these devices appeared. enthusiastically. "I turned and headed right back through Fish -finders work in a way very similar that school and after an additional 30 to sonar systems, popularly termed "under- minutes hauled back with 14,000 pounds. sea radar." Ultrasonic impulses of electron- The rest of the fleet held their original ically generated energy are transmitted course, and when they hauled back two through the water. Upon contacting fish, hours later each boat had only 1000 to the energy is reflected back to the ship as 3000 pounds. After that, my only trouble an echo signal. This signal is then trans- was the other boats pressing in on me as lated by indicating units into information they knew I was only fishing when I saw that reveals the location of the fish. fish. That problem is solved now. They all The successful results obtained with have their own 'Fishscopes'." these devices when used by commercial fishing enterprises seem to justify their Depth- Sounding and Navigation Aid initial cost. For example, using Minneapo- In addition to locating sea food, most lis- Honeywell's "Sea Scanar," the whaler fish -finders are readily adaptable for other "Nahmint"-out of British Columbia - related applications, such as depth- sound- caught 539 whales during a recent season. ing and locating submerged objects. The According to the harpoon gunner, a large Bendix DR -12, for instance, furnishes two part of this catch would not have been scanning beams, selected by the operator. made without the scanner unit. A wide beam is used for locating fish,

August, 1955 27

AmericanRadioHistory.Com Panoramic view of undersea area is obtained with "Sea Scanar." As its "eye" automatically sweeps back and forth over a 180° angle. fish and other underwater objects show up as pips of light on screen of cathode -ray tube. Range and scanning angle are selected by operator.

while a narrow beam provides an ideal Bendix Aviation Corp., Pacific Division, scan for navigation. N. Hollywood, Calif.-The "Fish Magni- Similarly, RCA's "Fischlupe" provides fier" is an attachment for use with subsurface information and is so sensitive various models of the Bendix Depth that it detects and shows whether the in- Recorder. It provides a magnified view dication on the CRT scope is being caused of any underwater section already de- by a single fish or a school. tected on the recorder. Indications are Unique for its size and weight is Raythe- by stylus traces on a chart. Ranges are on's "Fathometer." This device, said to be available up to 25 fathoms (150 feet). the world's smallest portable electronic Edo Corporation, College Point, L. I., N. Y. unit of its kind, can be employed in a row- -The "Fishscope" shows pips on the boat and is especially recommended for use screen of a 7" CRT indicator. Any 10- in rivers, lakes, and shoal waters. fathom sector can be magnified 25 Size, complexity, capability, and price of times. Maximum range is 250 fathoms. these units vary considerably, depending Components are self- contained and can on their intended use. The following is a be readily interchanged. list of typical manufacturers of such equip- Minneapolis- Honeywell Regulator Co., ment, together with representative com- Marine Equipment Division, Seattle, mercial models which are currently avail- Wash. -The "Sea Scanar" presents a able. "plan position indicator" (PPI) type

A 25% increase in size of catches is reported by E. Smola of Virginia. Below, school of fish appears on screen of Edo "Fishscope."

ELECTRONICS 28 POPULAR

AmericanRadioHistory.Com Permanent record of area scanned is available using Bendix equipment. Pattern made on chart by moving stylus indicates presence of undersea objects.

display on a CRT screen. Effectively a "picture" of the area being scanned, this display is accompanied by audible echo signals as in a standard sonar system. Range is over 265 fathoms. RCA Radiomarine Corp. of America, New York, N. Y. -The "Fischlupe" provides horizontal traces on the screen of a 7" CRT indicator. An expanded view of any 8- fathom vertical section is available. Range is 320 fathoms. Raytheon Manufacturing Co., Waltham, Mass. -The "Fathometer" presents stylus traces on a chart. This portable unit will operate for eight hours on a single 6 -volt storage battery. Its range is 40 fathoms. Additional information on any of these models may be had by writing to the individual manufacturer. -D0f-

Fish and other undersea objects show up clearly on the RCA Wischlupe." In- dications on the screen of the cathode - lay tube are in the form of short horizontal traces. Any 8- fathom sector can be magnified to provide more accurate data.

Smallest portable fIshfinder is Raytheon's "Fathometer." Within its limitations, this unit performs the same functions as more powerful devices. It is intended for use in lakes, rivers, and shoal waters. Indica- tions ore made by stylus traces on chart. 29

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perfect balance. Until balance is achieved, Electronic Juggler the machine quivers, jiggles, and jumps. A servomechanism finally gives the cue that SCIENCE'S FIRST "Electronic Juggler" was the rod is balanced. U. S. Depart- a stellar attraction at the The "juggler" will then hold the rod in ment of Commerce's exhibit at the German perfect balance indefinitely without support of any kind. Should a current of air or some other force make the rod sway or start to fall, a computer will instantly determine how far the balancing cup-in which the rod stands -should be moved to keep the rod in an upright position. The computer then transmits its solution to the servomechanism, which automatically moves the balancing cup as required. Engineers say that this demonstration of continuous "juggling" symbolizes the power of computers to perform feats of automatic control in industry. 30

A.C. -D.C. Converter

SAID TO INCREASE the efficiency of an electric shaver up to 60' , a new model of the "Bing Crosby Shavex" c o n - verts alternating current (a.c.) to direct current (d.c.). Announced by the Shavex Company of Los Industries Fair held recently in Hanover, Angeles, Calif., Germany. it uses minia- Built by Reeves Instrument Corporation, t u r e compo- of New York City, the "juggler" is a ma- nents and is chine that demonstrates the abilities of U. L.-approved. analog computers. It contains its own elec- Priced at $7.95, the "Shavex No. 911" tronic brain, eyes, nerves, and arm muscles, should be available wherever electric all of which combine to hold a steel rod in shavers are sold. 30

AAAA A.A.41,ALA AA AAAAAA AAAAAAAAAAA If by the Philco Corporation, Philadelphia, Is Smallest and Fastest Pa. Named "Transac" (short for Tran- A MINIATURE ELECTRONIC "BRAIN," claimed sistor Automatic Computer), the device op- to be smaller, lighter, simpler, and faster erates at phenomenal speeds, can control than any yet revealed, has been announced the most complex mechanisms, and yet is about half the size of a shoe box. It can be operated on ordinary batteries. "Transac" can multiply two 6 -digit numbers, such as 956,845 x 934,564, and give the correct answer in 48 one -millionths of a second. Applications include its use in digital computers and automatic control equipment in business, industry, and the armed forces. Because of its size and speed, the unit is said to presage mass production of transistorized computers, as well as to provide a long step toward the development of what scientists call a "universal computer." 30

30 POPULAR ELECTRONICS

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By E. D. MORGAN THE Equipment is tested, dropped, L. pounded, and burned before it is rated as safe and tagged with the Underwriters' okay. LABEL AFAMILIAR SIGHT on much electrical ply that it will perform better than one and electronic equipment used today not so approved. It does mean, though, is an Underwriters' Laboratories label. Ex- that the chance of setting a house on fire actly what is implied by the use of this is negligible if the approved model is used. label, however, is often misunderstood. No conceivable method of testing is over- Underwriters' Laboratories, Inc. is a looked. Much of the test equipment is of non -profit organization sponsored by the U. L.,'s own design and they dream up dia- National Board of Fire Underwriters. Its bolical plans to subject samples to the function is to test and inspect materials meanest treatment possible. They try to and equipment to prevent loss of life and anticipate all of the mistakes that could property from fire, crime and casualty be made by a consumer. Appliances are hazards. To do this adequately, it sub- left on for weeks and electric heater cords jects devices to grueling tests. Only the are twisted and untwisted thousands of hardiest designs survive and earn the right times. to the coveted label of acceptance. Television cabinets get a thorough It is important to point out that U. L. pounding before they receive U. L. ap- approval does not guarantee quality of proval. A large picture tube can be a performance. The testing is concerned deadly weapon when broken, as it hurls primarily with the safety aspects of equip- tiny fragments of glass in all directions. ment. Thus, the label on an approved To insure against injury, the safety screen radio receiver, for instance, does not im- on the front must be capable of with-

Electronic equipment is often used by U.L. technicians. Here. the split- second operation of a burglary detection system is photographed. Accu- racy is assured by using a cathode -ray oscilloscope, a beat - frequency generator, and various meters.

August, 1955 31

AmericanRadioHistory.Com Television sets are subjected to a thorough going - over by Underwriterá Laboratories, Inc. engineers. Special attention is paid to shock hazards and to overheating problems. Cabinets are pounded and safety glass hit with steel balls in test.

standing such shattering. A pound- and -a- sponded to each fire alarm at the fair- quarter steel ball is hurled at the set to grounds. If the cause were electrical, he determine its fitness for this purpose. would try to locate the defective device To determine whether a safe is fire- and determine why it failed. proof and burglar -proof, U. L. employs its Because of Merrill's insistence on thor- own staff of "arsonists" and "safecrackers." ough testing before the lamps were in- These men are masters at their trades and stalled, and correcting their faults before tackle a new item with drills, sledges, offering them to the public, Underwriters' torches, and explosives. Just to make sure, Laboratories, Inc. was born the following the safes are dropped onto concrete from year. Merrill was its first president. a second -story level, then placed in a 2000° Since then, U. L. has mushroomed. Over F furnace for an hour or so. If the inter- 375,000 products have been found accept- nal temperature goes high enough to turn able under its rigorous standards. Testing valuable papers brown, what is left of the laboratories are located in Chicago, New safe is returned to the maker with regrets. York and San Francisco, with representa- Fire doors are tested in large gas tives in nearly 200 cities insuring that the furnaces where flames lick at them until standards are upheld at the factories. The they are red -hot. Then a fire hose is in- work is financed solely by charges made to termittently played on the other side of manufacturers for the inspection of their the door. Acceptable fire barriers must equipment. pass the fire endurance as well as the hose Annual lists are published giving the stream tests. manufacturers' names and their approved products. Four main lists are prepared U. L.'s Growth which cover: electrical equipment; fire The organization had its unique start protection equipment; gas, oil and miscel- when bulbs were installed at the first laneous appliances; and accident hazard, Chicago World's Fair in 1893. These be- automotive equipment and burglary pro- came the Fair's chief attraction-as well tection. as its greatest hazard. Fires, started by Good will and impeccable honesty is the not -yet -perfected lamps and wiring, the main stock-in -trade of this organiza- were commonplace. This led a group of tion. U. L. never solicits business, but in- New England insurance interests to au- dustry has learned that it is well worth the thorize William H. Merrill, a young engi- effort to make sure its products deserüe the neer, to investigate the situation. He re- U. L. label. 30 ELECTRONICS 32 POPULAR

AmericanRadioHistory.Com An enclosed heavy-duty switch is tested in one of U.L: s many laboratories. Equipment such as this is operated repeatedly under excessive loads before it is approved and given the U.L. label.

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These are only a few of the authorized labels used by U.L. to desig- nate approved equipment. An item bearing such a label has met specifications and passed severe tests.

Automatic flatiron is dropped four times during continuous operation test of 500 hours. Temperatures cf various parts as well as operation of the thermostat are also checked.

August, 1955 3 i

AmericanRadioHistory.Com Shown here is the dis- sected papillary muscle of a cat. Attached to one end of the muscle is a loop of silk thread.

ANSWERS to the riddle of what causes pulls, by means of a thread fastened to it, heart disease may come within our own the wire of an electronic strain gauge.* lifetime, thanks to the studies now being A record of this action is made by a direct - conducted with the aid of special electronic writing electrocardiograph. One of the de- equipment. sign features of this device is its push -pull Medical authorities have learned, for ex- input circuit which has excellent rejection ample, that the heart is a natural elec- of 60 -cycle a.c. interference. The sensitivity tronic pump. Electrical impulses stimu- of the recording instrument is adjusted so late its action. Even when the life vitality that the needle will draw a diagram of is ebbing out of an isolated and dying seg- convenient size. ment i of heart muscle, scientists can re- Ten seconds before the electrocardiogram new its vigor for a time by injecting into is produced, showing how a certain drug it controlled bursts of electrical energy. effects the heart muscle, the level of fluid To simulate an important life process, in the chamber is lowered about 1 cm. be- scientists of the Cornell Medical School at low the base of the muscle to prevent the New York Hospital devised the electronic short -circuiting of the recording electrodes and chemical apparatus shown here, and by the fluid, as well as to prevent the in- have conducted experiments that reveal troduction of too large a shock artifact new data about the heart. in the recording. Electronics serves two purposes in this The photographs here show how this ap- effect of work : first, an electrical shock is given paratus is used to measure the to the muscle; second, electronic instru- drugs on the heart. But this is only one ments measure and record the results. of the experiments made possible with this One very important advantage in using apparatus. The over -all study concerns one electrical shock to stimulate excitable tis- of the most important of all physiological sue is that the shock can be graded ac- reactions ... for, while you have two curately in strength. Once the shock is of legs, two arms, and many "spare" systems, threshold strength, further increase does your life depends on the continued elec- not increase the response. In other words, trical activity of the heart. -1}- there is a limit to the amount of muscle electrically. movement brought about The strain gauge is a resistance wire placed in one In the experiment shown here, a thyra- arm of a Wheatstone bridge circuit. The bridge is initially balanced. If a strain is placed on the gauge, tron stimulator called an "Electrodyne" its resistance changes and unbalances the bridge, the was used to produce pulses of very small degree of unbalance being an indication of the extent of the force exerted on the resistor wire. The amount voltages. At times, less than one volt was of unbalance may be measured by a galvanometer (in this case, an electrocardiograph). Here the unbalance enough to produce results. indicates the pull on a silk thread connected to a The stimulated muscle contracts and contracting bit of heart muscle. POPULAR ELECTRONICS 34

AmericanRadioHistory.Com Muscle is placed between electrodes in plastic holder at left. Silk thread is attached to electronic strain gauge for recording muscle's contractile force.

Close -up view, below, shows heart muscle between electrodes with thread going off to strain gauge.

MUSCLE

Finally, a glass holder is filled with solution through which oxy- gen is bubbled, and heart muscle is stimulated electrically. Drugs such as digitalis are added. Re- cording instruments indicate effect of drugs upon electrical potentials developed by heart muscles during contraction, and on its contractile force. New heart medicines are tested elec- tronically in similar manner.

August-, 1455 35

AmericanRadioHistory.Com Liquid Chemical Provides First Aid for Electronic Circuits ELECTRONIC EQUIPMENT often suffers from tion displays no resistive, conductive, or one basic difficulty- failure of contacting capacitive values even when used in critical surfaces on control mechanisms. Oxida- v.h.f. and u.h.f. circuits. tion and carbonization may cause high Smoother and quieter operation of small resistance connections, intermittent op- motors and converters has been achieved by applying "Contact" with the motors running. Servicing of controls such as rheostats and potentiometers is aided by use of the liquid. The arm of such a control may become oxidized, carbonized, or otherwise coated with poor conducting material. Loose pieces of carbon in carbon - type controls often stick to the control surfaces. A few drops of the solution clean the contact arm and remove the loose particles. At the same time, the coating of "duralube" is provided. The application of "Contact" on delicate mechanisms such as timers, counters, computers,

A few drops of the chemical will clean and restore the switch contacts in this tuner. eration, pitting, and arcing. In many cases, the first and obvious approach to this problem has been to replace the defective parts. But any replacements, after exposure to the same operating conditions, will probably suffer the same defects. To solve this problem, one manufacturer, Beaver Laboratories, has produced a cleansing and restorative liquid called "Contact " -a colloidal solution with a hydrocarbon carrier base. Its capillary action enables it to penetrate into ordinarily Cleaning the shaft of a potentiometer. inaccessible places. This solution cleans contacts and moving and thermostats is recommended by the parts instantly. It also deposits a coating manufacturer as the "ounce of prevention of "duralube," a hard -bonding dry lubri- that prevents pounds of replacements." cant which plates the contacting surface As a "get- acquainted" offer, Beaver Lab- and resists corrosion, heat and cold. oratories will send out free samples of The non -flammable cleansing action of "Contact." To get a sample, send 15 cents "Contact," combined with the restorative to cover mailing and handling costs direct action of the "duralube" contained within to the manufacturer, Dept. 3B, 86 -51 Palo it, has many uses in electronics. The solu- Alto St., Hollis 23, N. Y. 30 AAAAAAAAAAAAAA4.11.41 Powerful Wireless Intercom

No INSTALLATION OR CONNECTING WIRES are needed with the wireless intercom which has just been introduced by Semco Electronics Corp., manufacturer of the "Page Boy" electronic "baby sitter." This two -way communication system has a range of up to several miles and is said to be the most powerful wireless intercom yet designed. Each unit is housed in a mahogany or ivory Plastikon cabinet of sufficient weight to prevent sliding. The "press -to-talk" control can be manipulated with finger-tip pressure. List price is $69.95 per pair in mahogany, $74.95 in ivory. For further information, write to Semco Electronics Corp., 17 Warren St., New York, N. Y. -® 36 POPULAR ELECTRONICS

AmericanRadioHistory.Com .D`. : d "Mr. Meticulous" Makes Transistors

This robot -like machine builds the delicate jurction trcnsistor and then runs a series of tests on it -all within one minute

AMACHINE that can perform more than 15 irtricate steps automatically in making experimental transistors -the solid pea -sizec amplifiers that have most of the advantages of vacuum tubes -is now in development at Bell Telephone Labora- tories. It is familiarly known as "Mr. Me- ticulous." In less than one minute, this unique machine will take a tiny bar of a special semi- conducting material, such as germanium or silicor -a bar almost as thin as a human hair -ex amine it carefully for electrical characteristics, and accept or reject it. If it accepts the bar, the machine will fix a fine gold wire to a critical point on the bar

Bell Labs scientist R. F. Riesz checks operation of "Mr. Meticulous." Machine produces four -element i..anction transis tors, never gets tired. makes no errors.

August 1955 37

AmericanRadioHistory.Com .1.14411y444; AslI144)0+9Mti:T o,.v,v4ti111 n,;..w1YRq!' h!!l.,... L- S ig.slpilf.:3' r F54

within an accuracy of 1/20,000 of an inch. rode transistors are very promising for use Then, still within one minute, it connects at relatively high frequencies and for this wire to one of the four wires leading broadband applications such as television out of the transistor; flips the bar end over and large bundles of telephone conversa- end; repeats the entire operation with an- tions. other wire on the opposite side; and finally runs a series of electrical tests on the com- How "Mr. Meticulous" Works pleted transistor. To utilize "Mr. Meticulous," an operator first places Junction Transistors for Research an n -p -n "sandwich" of germanium-as short as the head of a match and Transistors for research purposes must only a little thicker than a human hair - be of the highest precision and accuracy. into a clamp on the machine. The machine When fashioned by human hands over any then presses a very thin strand of gold wire extended period of time, some transistors against the bar and the wire edges along are produced which are substandard and the bar with minute steps of 1/20,000 of an useless for research purposes. This is the inch; after each step, the device takes a result of fatigue on the part of the tech- quick electrical look to see whether it has nician. But "Mr. Meticulous" never gets reached the thin (1 /10,000 of an inch) cen- tired, never loses his precision or accuracy. tral layer of germanium to which it must His hand never shakes and his highly or- bond the wire. As soon as the wire touches ganized electronic "brain" rarely has men- this layer, the machine starts measuring tal lapses. width until the wire reaches the far side of Originated by R. L. Wallace of Bell Tele- the layer. The machine then decides phone Laboratories, the machine may whether the bar is satisfactory. If it is some day be a pilot model for industrial not, it can be automatically rejected. machines to be used in assembly line tran- If the bar is acceptable, "Mr. Meticu- sistor manufacture. At this stage, how- lous" retraces his steps to the other side of ever, "Mr. Meticulous" is primarily a lab- the central layer and counts forward a pre- oratory device designed to aid research on determined number of steps. At this point, so- called "junction" transistors. a shot of electric current is used to attach The commonest form of the junction the wire to the germanium. The machine transistor is a three -layer "sandwich" of then attaches this wire to one of the four germanium sealed in a metal can a frac- leads of the transistor itself, and rotates tion of an inch in diameter. Wire leads the bar of germanium end over end. It connect to each of the three layers and automatically goes through the same series extend outside the can. This transistor of operations on the other side of the bar. performs the same functions as some Finally, the machine runs a series of elec- vacuum tubes -for example, it amplifies trical tests to determine whether the com- radio signals. pleted transistor has the proper operating The new type of transistor assembled by characteristics for research purposes. If "Mr. Meticulous" (although he can build the transistor fails any of the tests, it can other junction types as well) has a fourth be automatically rejected. If it passes, "Mr. wire which is attached to the central layer. Meticulous" puts it aside as finished busi- For this reason it is called a "tetrode" or ness and goes on to the next bar of tran- four -element junction transistor. Such tet- sistor material.

Enlarged view of a completed transistor, shown beneath the edge of a U. S. dime, highlights the unit's tiny and delicate structure. The wire in the photo is almost as thin as a human hair. 38 POPULAR ELECTRONICS

AmericanRadioHistory.Com "OVER THE HORIZON" t. TRANSMISSION

Super -powered transmitters beam TV and phone signals up to 200 miles without help from relay stations

DIRECT television and multichannel telephone transmission through space for as much as 200 miles -without relay stations and at ultra -high frequencies -is now a reality, according to announcements by Bell Telephone Laboratories and the Mas- sachusetts Institute of Technology. Video and audio information can both be sent "over the horizon" on u.h.f. channels in an extension of a transmission technique recently applied to the continental defense system. Over -the- horizon transmission means that longer communications bridges are possible This was disproved after years of re- over; water and rugged terrain. In the search at M. I. T. and Bell Telephone Lab- present microwave radio relay network oratories. The Bell Laboratories' research across the United States, relay stations are stemmed from Bell's success with trans - only about 30 miles apart. continental microwave systems for carry- Standard AM radio broadcasting em- ing telephone conversations, radio and tele- ploys waves that follow the earth's curva- vision programs from coast to coast, and ture. But waves used in television and their continued interest in radio propaga- telephone relays were presumed to travel tion. The M. I. T. interest was stimulated in a straight line. For many years, "line of by work for the Government in radar and sight" transmission between antennas overseas broadcasting. placed on towers on the horizon (about 30 Scientists knew that ultra -high frequen- miles apart) was thought to be the only cies traveled "over the horizon" under cer- practical means of transmitting by radio tain conditions but believed them to be too the wide bandwidth needed for television weak and undependable for practical use. In and multichannel telephone service. the course of investigating occasional in- August, 1955 39

AmericanRadioHistory.Com I 1 *4,-14, ., Rl+pw!s't`1- . ,f:krr-. . y.

terference attributed to these waves, how- with available equipment sufficient power ever, the scientists discovered that many to attain a satisfactory degree of re- actually overshot the relay towers they liability. were aimed at and arrived at farther Even after scientists learned that trans- points with remarkable consistency. mission was possible "over the horizon," The next step was to provide reliable they were not certain that this medium long- distance transmission "over the hori- would support the broad band of frequen- zon." Engineers did this by erecting larger cies needed for multichannel telephone or antennas and using higher power than is television transmission. In the fall of 1953, employed in the conventional microwave they found that they could transmit 12 ! system. Thus, they put to use the weaker voice channels "over the horizon." Tele- signals that drop off a straight radio beam vision was first successfully transmitted beyond the horizon and are reflected or this way in 1954 between Bell's Holmdel, scattered to distant points by the atmos- N. J., laboratory and the M. I. T. Round r phere. Hill Research Station near New Bedford, The effect of the new system is very Mass., a distance of 188 miles. much like that of a powerful searchlight Bell and M. I. T. scientists emphasize which casts a beam in a straight line. A that this success with over -the -horizon searchlight aimed at the sky can be seen transmission will probably result in a sup- from the ground miles away, even when plement to- rather than a replacement of the searchlight is behind a hill. This is -line -of -sight radio relay systems. possible because some of the light is re- Over -the -horizon signals are not to be flected and scattered by the atmosphere. confused with a similar type of transmis- In order to make use of over- the -horizon sion known as "ionospheric scatter," which transmission, 10 -kw. transmitters and 60'- is useful in long- distance transmission of diameter antennas are being employed, telegraph signals at relatively low frequen- representing 20,000 times the power and 30 cies. Unlike ionospheric signals, the over - times the antenna area used in the present the- horizon technique provides signals that transcontinental microwave system. It was are useful for the wide bandwidths re- found necessary to employ the lower fre- quired for a television picture or by many quencies (in the u.h.f. band) to develop telephone channels. -- AAAAAAAAAAAAAAAAAAAA Electrostatic Tweeter plate. Data on this unit, which retails at $5.00, are available from Kingdom Prod- DESIGNED AS A LOW -COST high frequency ucts, Ltd., 23 Park Place, New York 7, reproducer, the SKL -100 electrostatic N. Y. tweeter uses the electrical forces developed between the two plates of a capacitor Enclosure Has Adjustable Port as the source of its audio output. A thin THE NEW diaphragm "TUNE -A- PORT" speaker en- of polystyrene is covered on one closure may be adjusted by the user for side with gold leaf, while the other surface best tonal out- rests against a perforated metallic plate. put by means The gold leaf and the plate are connected of two external through a suitable network to the ampli- knobs that raise fier output. or lower the This type of speaker requires a bias d.c. port opening. voltage to stress the dielectric which is, in This bass reflex turn, modulated by the audio a.c. signal. type cabinet ac- The SKL -100 covers the frequency range commodates 12" above 5000 cps. "Highs" are distributed or 15" single - over a wide angle by the louvred deflection unit, coaxial, or triaxial loudspeakers. Ten thousand cubic inches of space are enclosed within its padded interior. Over -all size is 36" high by 24" wide by 17" deep. Retail price is $69.50. For complete details, write to the manufacturer, Standard Wood Products Corp., 47 W. 63rd St., New York 23, N. Y. -{-

40 POPULAR ELECTRONICS

AmericanRadioHistory.Com ._.._ y-4t .., - 4:

Empty spaces in 225 x 300' parking lot are readily spottsd cn television screen.

l TV for Parking Lots 4

ONE OF THE newest applications of closed -circuit television is in a parking lot. Mounted atop a light standard is a comp set, lightweight "TV eye" camera. It is connected to a 21" receiver located in the lct's entrance booth. When a motorist drives into the lot, the attendant need only glance at his TV screen to locate a vacant space. The "TV eye" may be rotated to provide a complete view of all sections of the parking field. The installation shown here is used by the Downtown Merchants Association, Oak- land, Calif. Photo at top is an actual shot of part of the parking area, as seen by the The TV set is V=RHEAD attendant on his screen. CABLE housed in the hut shown in the center photo, while the simplified block diagram (right) shows how the system works. Note provisions for controlling pan and tilt of -all view UNDERGROUND CONDUIT the TV camera. Below is an over A -TV EYE CAMERA IN WEATHERPROOF of the parking lot, which has become a HOUSING place with the aid B -TV EYE CAMERA CONTROL IN TOWER. more orderly and safer C -21" MONITOR IN ENTRANCE SHACK. of electronics. 3Ô D -PAN AND TILT MOTORS. E -PAN AND TILT CONTROLS.

41 August, 1955

AmericanRadioHistory.Com Underchassis view of light- operated relay. The photocell and lens assembly, which makes use of a rubber attachment plug, is mounted on the left chassis flange.

Using the CdS Photocell

PHOTOELECTRIC devices have myriads By MARVIN LUBIN of uses in homes, public buildings and factories. They may be used to open doors, WALLACE SAMUELSON count objects, warn of smoke or fire, or serve as intrusion alarms -to mention only a few applications. They are essentially Light -operated relay employing rugged and reliable, and have met with widespread acceptance. the new CdS (cadmium sulphide) There is one fundamental disadvantage inherent in the majority of the phototubes photocell has a number of uses and photocells presently available, namely, their low output current. To be useful, the output of the light detector must operate a relay, counter, or other device. Be- cause of the low current, an amplifier is rent flowing through it will be an indica- normally used to boost the output suffi- tion of light intensity. Under proper condi- ciently to be of value. The addition of the tions, this current may be sufficient to op- amplifier complicates the unit. erate a sensitive relay. Recently, a new type of photocell was A basic circuit for this type of device is introduced which has sufficient output, with shown in Fig. 1. Voltage is applied across proper illumination, to operate a sensitive the series combination of the photocell and relay or counter directly. Known as the a load. When the cell is dark, the resistance cadmium sulphide photocell, it is a photo- is high and current flow is very small. resistive type, i.e., its resistance changes Under illumination, current flow increases. when it is illuminated. The sensitive ele- This photocell is the basis of the very ment, a crystal of cadmium sulphide, has a simple, easily built, light- operated device very high resistance (ranging from hun- shown in Fig. 2. Here the operating voltage dreds of megohms to as high as tens of thou- is obtained by rectifying the line voltage sands of megohms) when it is dark. Its (117 volts, 60 cycles) to give about 130 resistance decreases very rapidly as more volts, d.c. Since the current drain is very and more light strikes it. Thus, if a voltage small, the rectifier, SRI, can have a rating is applied to the cell, the amount of cur- of only 20 ma., although a unit with a 42 POPULAR ELECTRONICS

AmericanRadioHistory.Com RLI SOI

4 PHOTOCELL VI

))1,

Pictorial diagram of relay.

TERMINAL LINE STRIP PLUG larger rating may be used if desired. Sev- this unit is very small, which means that eral alternate relays are given in the parts it will not intercept much light. Therefore, list; any relay with an 8000- 10,000 ohm a lens system was added to concentrate coil which will operate on 1 to 3 ma. is the available light on the photocell. A novel satisfactory. One advantage of this device (Continued on page 121) is its very low power drain when the photocell is dark. Under this condition, power consumption is negligible. Construction is extremely simple, as can be seen from the photograph. Any chassis of convenient size may be used. Mounting LIGHT of parts is not at all critical, as long as the SOURCE line voltage is well isolated from the chassis. The cadmium sulphide cell employed in

R1 -4700 ohm, I/2 w. res. C1 -20 Aid., 150 v. elec. capacitor SRI -20 ma., 130 v. selenium rectifier RYI- S.p.s.t. relay, 8000 -10,000 ohm coil (Sigma 4F; Relay Service Co. RS Midget'; Potter & Brum- Fig. 1. Circuit showing basic operation. field SS5D) VI- Cadmium sulphide photocell (Standard Elec- tronics CdS -3 Type DR -1.5 ma.) SOI- Chassis type a.c. socket (Cinch -Jones 2R2) SRI I-Rubber handle plug RECTIFIER 20MA. 1 -Line cord and plug + 1 -Lens. 11/4" diam., I" focal length SOI RI 1- Single lug tie point 4/K 1-4" x 6" x 2" chassis base OUTPUT Misc. screws, wire, solder, etc. H VI i17VA.C. *Available from Relay Service Company, 1310 -12 PHOTOCELL North Pulaski Rd., Chicago 51, III., at $3.30 each. CI Specify Part No. R-1000A for s.p.s.t. NC contacts, C, + 2opfd Part No. R -1000B for s.p.s.t. NO contacts, and Part No. R -1000C for s.p.d.t. contacts. This latter relay

is $3.50. RL I "Available from Standard Electronics Div. of Hupp O.C. RELAY S.P.S. T. Corporation, P.O. Box 513, Carlisle, Pa. at $3.95 9000A each. Total cost of parts, approx. $11.90 Fig. 2. Schematic diagram of the relay.

August, 1955 43

AmericanRadioHistory.Com 6'. IF.:1Ç,'+,114!!?.M..!!.-w4F'k_711k,!I'K.:- , ..

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By GEORGE BERRY would spoil the neat simplicity of our example. The schematic is shown in Fig. 1. Strictly for the beginner; Now let's proceed through the mental processes that go with wiring it up. the how and why of radio First, mount on a board those parts which ought to be screwed down. That or electronic schematics means the tube socket and the tuning capacitor. Let's use a big board and set the plus pictorial vs. wiring batteries on it too, so that it can be carried around. There are few sounds as discour- aging as the "clunk" of a heavy B battery IF YOU enjoy building and experimenting plunging to the floor, accompanied by the with electronics, but still feel a bit shaky ripping noise of taut wires pulling radio about wiring up circuits directly from the parts out by the roots. schematic diagram, take heart. Pictorial The coil can be screwed down, too, if it diagrams are all right to start with, but has a bracket. Some screw terminals or they are not as easy to follow as they look. Fahnestock clips for the antenna, ground, But schematic diagrams are actually much and headphones need to be fastened on as easier to understand than they would seem well. Now we are ready to wire. Starting to be. Most of them are a lot simpler than, at the left, we see that the antenna termi- say, a road map, and easier to figure out nal, one end of the coil, and one side of than a diagram of an end -run play in foot- the tuning capacitor C2 should all be con- ball. nected together. Do so. Next, and rather Let's assume you already recognize the naturally, the ground terminal, the other standard symbols for the common parts - end of the coil, and the other side of the tube, capacitor, resistor, and coil ... bat- tuning capacitor C2 all go together. The tery, headphones, antenna, and ground. frame side of C2 is always the ground side. Once you have some idea of what these Now note that the little mica capacitor CI different gadgets do, it's almost impossible and the resistor R1 are connected directly to mistake what the symbols mean. They were designed that way. The idea of the schematic diagram is simply to show what is connected to what, in the simplest, most direct manner possible. You can take a schematic and compile from it a list of what connections to make. Then you can follow that list with a soldering iron and pliers and the circuit will be all wired up. Experienced people, including engineers, usually do this mentally while they are working. Let's take an example, say, the simplest possible one -tube radio receiver. This set will work, incidentally, but don't build it except for practice. A very few more parts would make a vastly better set, but that 44 POPULAR ELECTRONICS t

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across each other. Let's solder them to- direct way. A wire from socket pin #2 gether, and then see where the combination should go to the frame (ground) side of goes ... one end goes to pin No. 5 on the the tuning capacitor. It can be easily tube socket while the other end goes to the routed around via the terminal on Li. tuning capacitor -that side which is con- Color should be black for ground, negative, nected to the antenna. and such things, if we are particular. As Where do the other socket terminals go? the B battery will be sitting alongside the six Well, No. 3 goes directly to one side of the A battery, let's make the wire about phones. While we are at it, let's take care inches longer than necessary. Skin the in- of the other side of the phones. A long wire sulation six inches back from the end and goes to the positive side of the B battery; connect that to "A minus "; then skin the make it red for "+ ". Now there are only end and connect that to "B minus." It is two connections left on the socket. Pin simpler that way. . . . except No. 2 goes to the negative side of the A bat- Now we ought to be finished tery, so let's solder a wire there. It goes to a for pin No. 7. That goes to the plus side couple of other places, too. In fact, it looks of the A battery, and nowhere else. Better as if pin No. 2, the "A minus," the "B put a clip on the battery end of the wire minus," and ground are all connected to- so we can turn off the unit. gether. Does it matter just what wires go Clip a wire from a water pipe or bed- where, so long as these four places are all spring or something onto the "ground" ter- connected together? Well, it matters at minal, drape ten feet of old magnet wire v.h.f., but not down here in the AM broad- from a defunct auto speaker field over cast band. Let's do it in some reasonably (Continued on page 102)

LI C2 HEADPHONE CONNECTIONS

ANT OCTAL SOCKET IG4GT TUBE VI

GND (TO CHASSIS) 82 B BATTERY

BATTERY BI

Fig. 1 (facing page). A wiring schematic contains the identical information conveyed in the pictorial schematic (Fig. 2 at the right). Beginners tend to favor the use of the pictorial; but once familiar with the essentials behind the true wiring schematic. it becomes obvious that the latter will always be best. August, 1955 45

AmericanRadioHistory.Com ,17tt ;,;ùd., k1.4!'", F ik a.1y ;s.. ;lh tff qá':y"r! ; 'PI°Twromr,'°'! !!iolwrril

External view of the tester showing a cigarette on the right for a comparison of size. The neon bulb is mounted in a rubber grommet on the panel near the cigarette.

the cells may be checked by observing the brightness of a flashlight bulb inserted in the socket, inexpensive cameras like the Hawkeye Flash and the Kodak Duoflex I and II cannot be tested this way. The simple little tester described here can be made up for less than $1.50. It checks the flash equipment right at the flash -bulb socket, with or without film in the camera. This kind of test reports simultaneously the condition of the dry cells and the cleanliness of all internal contacts. All that's needed is a spent flash bulb of the right size, an inexpensive filament \ transformer of the 6.3 -volt variety (a Stan - cor P -6134 was used in the author's model), an NE -2 neon lamp, a small box of metal or wood, and two rubber grommets. The test plug that goes into the flash socket is made from the base of the Flash -Gun burned -out flash lamp. Wrap the latter in several layers of cloth and break the glass by rapping it with a hammer. Break away most of the glass shards with a pair of pliers, then soak the metal portion in boil- ing water for about five minutes to soften the cement. After this, the remaining par- By HARVEY POLLACK ticles of glass can be removed easily with a screwdriver. Unsolder the old wire leads from the center contact and the brass shell, and then resolder a 2' or 3' length of twin Why waste good film on flash line cord to the base as shown in the illustration. To finish the plug neatly, fill the hollow with molten sealing wax or ordinary shots when this indicator will paraffin. Wire the circuit as shown. The NE -2 test your flash gun's operation lamp projects up through the hole in one of the grommets and is firmly supported by friction; the remaining grommet is used FOR THE as an exit hole for the test lead carrying CAMERA USER, nothing is so the plug. aggravating as a flash bulb which fails to go off when a crucial, When the flash equipment is ready to be never- to- be -re- tested, plug peated scene is being photographed. Al- the remodeled flash -bulb base though many flash guns are equipped into the socket. If there is film in the with camera, cover the lens with a "test" position in which the condition of a piece of cardboard to avoid fogging the film. If the neon tube flashes when the shutter is operated, the batteries and contacts are good; if it fails to do so, the bulbs will not fire! The principle of operation is so simple that practically nothing can go wrong. As the shutter makes instantaneous flash contact, the cells in the flash gun send a pulse of current through the 6.3 -volt winding. This Wiring schematic of the flash -gun tester. voltage is stepped up by transformer action Note the simplicity of the circuit which to a potential sufficiently high to fire the uses a filament transformer and a neon neon lamp. If the cells are weak or the bulb. The plug to the flashgun bulb constacts are dirty, the neon lamp will not socket is made from discarded bulb base. glow at all. 30 46 POPULAR ELECTRONICS

AmericanRadioHistory.Com Build Your Own Applause Meter

By LOUIS E. GARNER, JR.

AMATEUR CONTESTS are never com- Add a professional touch to plete without an applause meter of some kind. Here is a unit that will add a local amateur talent contests professional touch to any amateur show - whether at a church benefit, a local high and shows with this simple, school show, a lodge show, or a civic group's charity performance. easily built applause meter But an applause meter need not be con- fined to the job of judging contests. Since it is basically a simple sound level meter, it may be used in dozens of other applications -from checking relative noise levels in an industrial plant to determining the efficiency and performance of a p.a. system by checking sound levels in various parts of an auditorium. Assembling this applause meter can be a lot of fun. Standard, easily available parts are used throughout, and the circuit is simple and foolproof. Little or no difficulty will be encountered even by the beginner in building the unit -one or two evenings or a single weekend will provide adequate time. Construction As can be seen from the circuit diagram (Fig. 1), this device is basically a three - stage amplifier fed by a loudspeaker used as a microphone. The output of the amplifier is rectified and passed through a 0 -500 microampere meter. Thus, the meter deflection is directly proportional to the intensity of sound striking the speaker microphone. A standard wall -type loudspeaker baffle

View of applause meter as seen by contest judges. Ordinary clothesline cleat serves as a support for the power cord. August, 1955 47

AmericanRadioHistory.Com was used as a cabinet for housing the model. fit. In the author's model, imperfections in Four rubber feet are attached to its "base" the speaker baffle left several gaps between and a kitchen cabinet handle to its "top." the panel and the baffle "cabinet." If a snug, Almost any type of housing will serve as tight fit is obtained, a few 1/2" holes well should -a metal utility box, the cabinet from be drilled either in the sides or in the top an old table -model radio receiver, or eyen a and bottom of the cabinet. These serve the home -made wooden box. The chassis and dual purposes of providing ventilation and control panel are of aluminum. A commer- keeping the speaker from being "muffled" by cial chassis base (ICA No. 29080) was used a closed air chamber, with a resulting drop in the model, but a satisfactory chassis can in sensitivity. Standard decals are used for G be bent from sheet stock if preferable. Di- labeling the controls. A clothesline cleat is mensions are not critical. The panel was cut mounted on the panel and serves as a holder from an aluminum cookie sheet, but any for the coiled line cord when the instrument stiff, durable material may be used, and is carried. even plywood or hard board, such as Ma- A 6" PM loudspeaker is used as a micro- sonite, is satisfactory. phone in the model, but any After size PM speaker cutting the panel to size, check its from a 2" midget to a 15" giant will do the

R1- 250,000 ohm volume control (audio taper) SI- S.p.s.t. toggle switch R2 -10 megohm, 1/2 w. carbon res. SRl -20 ma. selenium rectifier (Radio Receptor R3 -270K, 1/2 w. carbon res. Type 8Y1) R4 -220K, 1/2 w. carbon res. VI -Type SAlM tube RS -27K, y2 w. carbon res. V2 -Type 12ÁT7 tube R6 -47K, 1/2 w. carbon res. CR1 -Type 1N34 crystal diode R7 megohm, 1/2 -1 w. carbon res. M1-0 -500 microampere, 21/2" diam. meter (see text) R8 -220 ohm. 1 w. carbon res. 1 -6" PM loudspeaker (see text) R9 -1 megohm, 1/2 w. carbon res. I -7 -pin miniature tube socket R10 -10 K, 1/2 w. carbon res. 1 -9 -pin miniature tube socket RU -1K, 2 w. carbon or wirewound res. 1 -line cord and plug R12-47 ohm, 1/2 w. carbon or wirewound res. 1- speaker wall baffle CI -.005 pfd. disc ceramic capacitor 1- kitchen cabinet pull (handle) C2-0.1 pfd., 200 volt paper tubular capacitor 1- control knob C3, C5 -O.01 pfd. disc ceramic capacitor 1- clothesline cleat C4-10 pfd., 25 v. tubular electrolytic capacitor 2-2- terminal tie point C6-0.1 pfd., 200 volt metalized paper tubular 1- 7- terminal tie point capacitor 4-1/2' rubber grommet C7, C8 -20-40 pfd., 150 volt dual tubular elec- 1 -3/8" rubber grommet trolytic capacitor 1 -sheet of aluminum (about 8" x 10") for panel C9 -O.25 pfd., 200 volt paper tubular capacitor 4- rubber feet (optional-see text) 1- chassis (ICA #29080, 3" x 61/3' x 11/2") TI- Speaker output transformer, 5000 ohms pri., Misc.-ground lugs, machine screws, nuts, wire, 3.5 ohms sec. (Merit Type A -3026) solder, etc. T2 -Small power transformer: 150 v. @ 25 ma., 6.3 v. @ 0.5 amp. (Merit Type P-3046) Total cost of parts, approx. $28.00

27K

46K .Olptd. C5 Cptd. TI 6AU6 y 6 PM. RED VI 220K G3 12517 SPEAKER .Olptd. RIO .005Yfd. V2 10K CI 2 250K 6 270K RI R3 IN34 125

BLUE 39 CRI R7 i 9C 4C2 I MEG. mi J R2 10MEG. - Iptd. C4 R8 R9 10yT 220 1 MEG.

SENSITIVITY I K 47rL } RED T2 Rn RI2 ,.,t + 2ÓMA. BLACK C7 C8 SI ~~ 20 pto. SP.ST. T40ptd. 117V. RED AC. Fig. 1. Schematic diagram and GREEN parts list for the applause meter. BLACK GREEN NOT USED 9 VELLO V2 4 VI GREEN

48 POPULAR ELECTRONICS

AmericanRadioHistory.Com job, although the larger speakers may be amplifier. An output transformer is usual- slightly more sensitive. Use any PM speaker ly employed for matching. This "micro- that is available. It may surprise you to phone" characteristic is utilized in many learn that a dynamic loudspeaker will op- intercom systems where a single unit serves erate very satisfactorily as a microphone, as both loudspeaker and microphone. A provided that it is properly matched to the crystal or a high impedance dynamic

UNE TI PLUG

/ / // / GREEN- YELLOW (UNUSED) 70 SPNR / VOICE COIL / / T2 RI I / / R3 t1i':-/ /-

C7 CB

12 A77 SRI TUBE V2

6526 TUBE VI

Pictorial diagram of the applause meter, indicating the suggested method of wiring the various components. The photographs show location of the components on the chassis. August, 1955 49

AmericanRadioHistory.Com r''' w4"Frirr, microphone could be used in place of the be used on the stage of an auditorium loudspeaker. In such a or in case, the match- other places where a standard outlet may ing transformer, T1, would not be needed. not be Replace close by, install a long line cord -12' R1 with a 2- megohm control and to 15' length is not excessive. connect the microphone leads directly Circuit across it. Modifications: There are two circuit modifications which may be incorporat- When all chassis machine work has been ed in the instrument . . . (1) completed, mount the a simple "fil- transformers, tube ter" to reduce the sharp peaks caused by sockets and other components using small someone whistling, machine and (2) a meter other screws and hex nuts. Lock washers than the 0 -500 microampere should be inserted under unit used in the each nut or, as an model and specified in the parts list. To add alternative, each screw and nut can be a simple filter, connect painted with fingernail a small paper ca- polish. This step pacitor across the meter terminals, as shown will keep the screws from working loose at C9. The when the instrument exact value is not critical; try is carried about. Use sizes from 0.05 pfd. to 0.5 rubber grommets for protection pfd. to see which wherever gives the best results. Voltage rating is un- wires pass through the chassis or panel. And important. take care not to use excessive pressure when mounting the small A 0 -1 ma. meter may be substituted selenium rectifier SR1. without changes in the circuit, Place a fiber washer under the mounting but the in- nut strument's sensitivity will be reduced some- and between the rectifier and chassis to what. A 0 -200 serve as a "cushion." or 0 -100 microampere meter To minimize the will give greater sensitivity than chances of damage, mount the the 0 -500 meter last of unit, but it may be necessary to increase the all ... preferably after the wiring is com- size pleted. of R10 slightly to reduce "needle slam- ming" when the Wiring sensitivity control is turned Hints: Since the applause meter is up. Determine the best size experimentally. basically a three -stage audio amplifier, the same wiring precautions apply as in assem- Installation bling an amplifier. Lead dress is not too With the wiring completed and checked critical, but the input and output lead con- for errors, nections install the tubes and plug the unit should be kept well separated to into a wall receptacle. Turn avoid oscillation and component it on and allow leads kept it to warm up for a minute or so. Turn the as short and as direct as possible to avoid sensitivity hum control all the way up and speak and noise pickup. Use a hot, clean, a few words out well- tinned soldering loud. An up -scale deflection iron and rosin core should be obtained on the meter. solder, and complete all If a down - connections as scale deflection occurs, reverse the connec- quickly as possible to avoid heat damage. tions to the germanium Take special pains when diode (1N34). Speak soldering the ter- in a louder and in a softer voice. The louder minals of the selenium rectifier, as exces- the sive voice, the greater the deflection that heat can damage this component. should be obtained. It is best Try turning the sensi- to wire as much of the main tivity control back. As chassis as possible before it is turned back, attaching it to the less deflection should be obtained for the panel. Since the instrument will probably same sound level.

Top view of chassis after the two transformers have been mounted and before any of the wiring has been done. Location of tube sockets and rubber grommets can be readily deter. mined from this photograph.

50 POPULAR ELECTRONICS

AmericanRadioHistory.Com RS RIO :6 R12 SRI

R CI C2 C3 R7 V2 C5 R9 ,R8 C7.C8

Underchassis view with the major components identified in accordance with Fig. 1.

If a small deflection is obtained even when applause meter, set it on a table so that the there are no sounds in the room or when speaker faces the audience. One or more the sensitivity control is turned back, don't "judges" may watch it and record the re- worry. There may be some small hum or sults. Before a performance begins, ask the noise pickup in the circuit, but this will not audience for a good "hand." While they are prevent the instrument's use. If the "no applauding, set the sensitivity control so signal" deflection is appreciable, check the that the needle deflects about two -thirds or circuit wiring carefully. If necessary, shield three-quarters of full scale. Keep the con- the input leads. trol at this setting throughout the judging. To use the completed instrument as an -i-

View of chassis and panel removed from cabinet.

TI VI RI CRI MI V2

August, 1955

AmericanRadioHistory.Com Typical Clock Radio

Usually mounted on the back of all clock radios is a tag or sheet describing the operation sequence. Also outlined on the back cover is a diagram of the tube positions, "'switched" a.c. outlet, and controls for setting time on the clock.

Disassemble the clock radio in the same way that the ordinary household radio would be disassembled. Before slipping the radio chassis from the plastic case, note that the clock is plugged into the receiver chassis by a small two- or three - prong male plug. Pull this plug out and the receiver chassis will be free.

Should it ever become necessary to operate the radio without the clock, the "on -off " switch in the clock mechanism must be shorted. Use an ohmmeter to determine the correct terminals and connect them with a short length of wire. z` ta 7 11 1.3 }ó 52 POPULAR ELECTRONICS

AmericanRadioHistory.Com Clock radios differ from ordinary radio receivers in that they include an electric clock-this is how they may be checked

By H. LEEPER

Two spots to be checked for wear and tear are the connections to the loop antenna and the entry of the a.c. line through the chassis wall. If the former is frayed, it may be necessary to replace the wire to insure a good connection. If the a.c. line is cut or scarred, it should be replaced with fairly heavy a.c. cord (capable in some clock radio combi- nations of handling at least 1000 watts).

As is usual with most small a.c. -d.c. household radios, excessive hum or distortion is probably due to the filter capacitors. Replace them if they have broken open or are leaking. Use values shown on capacitor cartridge and carefully observe polarity (coloring of wires) when soldering new unit in place.

To check the appliance outlet, temporarily plug in a 100 -watt lamp bulb. Before plugging in the clock radio, of course, reassemble the connections to the clock motor and switch. Check the time when the appliance switch went into operation. Also note if there is excessive hum in the speaker. which in some cases may be due to the clock motor. If faulty time switching prevails or the hum cannot be corrected, clock may have to be replaced. August, 1935 53

AmericanRadioHistory.Com Build Your Own Geiger Counter Probe

wooden plug for the wire which attaches to the center electrode of the Geiger tube by means Handy method of adding another of a Fahnestock clip soldered to the end of the wire. This wire should be covered by polystyrene tubing or spaghetti to pre- G -M tube to counters utilizing vent leakage of high voltage. Mount the spiral holder for the Geiger tube the CK 1026 in 900 -volt circuit in a hole drilled lengthwise through the wooden plug, and bend back the end of the tube holder into another hole drilled about to increase flexibility greatly Y." into the wooden plug. A Fahnestock clip should then be soldered to the end of the Geiger tube holder where it is bent back, and the solder should be permitted to flow MOST inexpensive Geiger counters are around the end of the tube holder to affix it not supplied with an external probe. firmly to the assembly. Solder should also be Such a probe is very convenient to use in applied at the other point where the tube prospecting because it offers better expo- holder fits into the wooden plug. Care must sure to radioactivity. This article describes be taken so that no metal of the Geiger an inexpensive method of constructing tube mounting will touch the metal tube a when sturdy probe which will operate with any the plug is inserted into it. A clear- Geiger counter using a CK 1026 G -M tube.

Parts required are as follows : WIRE a spiral TUBE HOLDER FANNSTOCK CLIPS wire IS BENT SACK INTO holder for a CK 1026 tube, which can SECOND HOLE be purchased for a few cents from a supplier of parts and kits for Geiger counters or can be shaped from heavy -gauge bare copper wire; a CK 1026 Geiger tube; five feet of 4 double stranded wire ENO VIEW OF WOOD WIRE LEADS TO GEIGER TUBE COMM cable; two Fahnestock MOUNTING RING POLARIZED PLUG clips; a polarized two -prong plug with an insulated socket; and a s.p.d.t. slide switch. Geiger tube mounting in the probe. The probe is made from a metal tube approximately 8" in length and having a 1Y4" inside diameter. A nickel -plated brass tube GEIGER COUNTER CIRCUIT of these dimensions can be obtained from a A plumbing supply store for about 50 cents. I- J Make a wooden handle of any desired SPOT length from a round piece of wood of SWITCH the proper diameter with a Y4" hole drilled POLARIZED GEIGER TUBE IN COUNTER lengthwise through the center for the SOCKET wire cable. A cylindrical-shaped wooden e plug can then be fashioned to fit snugly q into NOTE ''Ui CONNECTS WITH CENTER ELECTRODE IN EXTERNAL the metal tube, and the Geiger PROBE. tube holder is mounted on the plug. Drill a small hole lengthwise through the Circuit adaptation for external probe. 54 POPULAR ELECTRONICS

AmericanRadioHistory.Com Finished probe assembly ready for attaching to a Geiger counter. The holes permit beta ray entry into the CK1026 tube.

ance of 1,4e should separate the soldered connections and Fahnestock clips from the outer metal shell of the probe. polarized plug at the end of the wire cable. Drill a network of holes into the metal The Geiger counter is easily adapted to tube for a length of three inches. These connect to the external probe. Remember should be about %" in diameter and evenly that it is important that the Geiger counter spaced so as not to weaken the structure of switch be turned off, as there are 900 volts the tube. The holes permit the passage of across the Geiger tube. The two terminals beta radiation to the Geiger tube which of a polarized socket are connected in paral- would not normally pass through the wall of lel with the Geiger tube terminals in the the probe. counter. Proper polarity of the socket con- Insert the CK 1026 Geiger tube into the nections is determined from the polarity of spiral holder, making a tight connection. the plug attached to the probe. The wire The wire cable is fed through the wood which connects the center (positive) elec- handle and the two wires are connected to trode of the Geiger tube in the probe should the Geiger tube mounting. Electrician's connect with the center electrode of the tape or a metal clamp should be placed on tube in the Geiger counter. the wire cable at the inside end of the handle Insert a s.p.d.t. slide switch in the circuit to take up the strain of pull on the cable. as illustrated, connecting either the probe Fix the handle and the wooden plug in place or the original Geiger counter circuit at one by means of small wood screws through time. Holes should be drilled into the Geiger holes drilled in the metal tube. A wooden counter's case to accommodate the socket plug is fitted into the end of the probe to and switch which are mounted in place with complete the assembly. Solder a two -prong small self-tapping screws. 30

may be used with 300 -ohm balanced input Filter Eliminates TVI systems or 300 -ohm twin lead. to manu- THE COMPACT HIGH -PASS filter -type TV For additional details, write the interference eliminator announced by Clip - facturer at 7390 Colerain Road, Cincin- pard Instru- nati 31, Ohio. ment Labora- tory, Inc., is in- Unbreakable TV Lamp tended for use with any video SOFT INDIRECT LIGHT iS cast by a new receiver having lamp which is designed to illuminate the a 40 - mc. i.f. TV viewing area in channel. Known the home. as the Clippard A thick felt pad "De Luxe Hi- under the base pre- Pass Filter, v e n t s scratching. Model No. The entire unit is 4125," it is said washable, color -fast to eliminate or and unbreakable. reduce interfer- Made by Peerless ence and reject Products Industries, or attenuate 812 -16 N. Pulaski 1 o w frequency Rd., Chicago 51, Ill., signals below this TV lamp is 50 mc. The unit listed at $4.95. .- - August, 1955 55

AmericanRadioHistory.Com I??s; t )Y« 1Ai. 14. .:;r {N= ?T¢! }N'lNt'M '7111.1 !+r9 `IMr!a

Plastic Tape Reels lems encountered with conventional aluminum reels and offers superior tape -han- MADE OF TOUCH, glass- reinforced plastic dling characteristics. instead of metal, the 10/2" magnetic tape An important innovation is the tiny cen- reel just introduced by Minnesota Mining ter hole, IY18" in radius, which is said to and Manufacturing Company, Saint Paul 6, provide more accurate centering, improved Minn., producer of "Scotch" brand mag- balance, and greater strength than the 3" center hole found in conventional 101/2" reels. The reinforced plastic material provides a reel that cannot be bent or permanently distorted, as compared to aluminum reels. Its one -piece precision construction replaces the three pieces of the metal reel normally held together by bolts, and eliminates the possibility of bolts loosening or being lost. Designed for use with equipment which accommodates 101/2" metal reels, the new netic tapes, incorporates new structural reel lists for $4.50. It holds 2400 feet of features. The first of its design to be com- "Scotch" brand No. 111 or No. 120 "High mercially available, according to the manu- Output" tape or 3600 feet of "Scotch" brand facturer, it eliminates many of the prob- No. 190 "Extra Play" magnetic tape. 30

Low -Cost Intercom station system lists at $19.90. The all -metal cabinets are finished in an attractive ivory "AN ELECTRONIC INTERCOM that everyone enamel and all units are U.L.- approved. can afford" is the description given by The master unit features an "on-off" power switch, volume control, and separate press -to -talk switch, while the remote unit can answer calls from a distance with no switch necessary for operation and is always "open" for baby- sitting or dictation. This new intercom is said to offer natural voice reproduction, with ample sensitivity and low hum and noise. The system costs less to operate than a 30 -watt bulb. Both Mark Simpson Mfg. Co., Inc., Long Island master and remote units measure 61/2" x City, N. Y., to its new Masco "E -Z TALK." 3%" x 41/2" high. Shipping weight of each Complete with 50 feet of cable, the two- complete system is 61/2 pounds. -50-

Short -Wave Hi -Fi Tuner to the "Brownie" L -300, "FM- only" tuner. As the first tuner to cover short wave, THE FIRST SHORT -WAVE AM tuner for high the L -500 enables audiophiles to listen to fidelity has been announced by Browning famous foreign orchestras, music festivals, folk music, special events, and news programs. Outputs connect to amplifier and speaker as well as tape recorder. The L -500 covers both domestic AM and the international short -wave band-19 to 49 meters. Sensitivity is under 2 microvolts, said to be comparable to the finest communications receivers. Other features are: broad and sharp AM tuning; full frequency response; 10 -kc. whistle filter; built - in high -gain ferrite antenna; cathode follower output to permit remote installation; and self- contained power supply. Now on display at hi -fi dealers, the L -500 is priced at $87.50 net. Specifications are Laboratories, Inc. Entitled the "Brownie" available at dealers or from manufacturer L -500, it is designed as a twin companion at 750 Main St., Winchester, Mass. -j- 56 POPULAR ELECTRONICS

AmericanRadioHistory.Com PLAYIN3 HANDLE PUSHBUTTON (S2) FILAMENT SWITCH (SI ) - TUNE-UP (R3)

LOUDS'EAKER

AMPLIFIER TERMINALS

_ -

By RUFUS P. TURNER

BUILDING an electronic organ is not a Enjoy leisure hours building task that should be lightly undertaken by a novice. However, there are many lit- and playing this music- maker- tle electronic "music- makers" that he can easily put together. Such gadgets are in- it has tonal quality similar teresting to build and fun to operate. This article describes a music -maker on to a violin, covers over two which a little over two octaves can be played -a range which will allow the octaves, is easy to operate player to strike up many simple tunes. Although far from being a fine musical instrument, the notes obtainable from this gadget have enough overtones to sound good; in fact, it sounds something like Music is achieved by swinging a lever - a violin. While it is intended primarily as type handle to locate the notes and press- an electronic toy for youngsters, older ing a push button to give the sound. No people will enjoy it also. sound comes from the loudspeaker until The electronic "whistler," so named be- the button is pressed. The sound continues cause of its output characteristics, has its as long as the button is held. A little own loudspeaker. But its output is rather practice will show how far the handle low, allowing it to be played without dis- should be swung for a certain note. Play- turbing others. If louder sounds are de- ing by ear is easy with this instrument. sired, this music -maker has two binding How It Works posts which can be connected to an external amplifier or to the audio stage of a The simple electronic "whistler" consists radio. Since it contains its own batteries, of a tunable oscillator (which generates the it does not have to be connected to the notes) followed by an amplifier and loud- power line, and so is safe even for small speaker. Two tubes and two batteries are children to operate. It can be held in the employed in the unit. hand or set on a table while being played. Figure 1 shows the complete circuit. August, 1955 57

AmericanRadioHistory.Com R2 IG4GT VI 27 K 5W 3S4 V2 CI 4 .01old BROWN

4111. C2 RIO PM 021MM_ DYNAMIC Y © SPEAKER V PLAYING RI ARM NOTES 50K 1 TO EXTERNAL RS AMPLIFIER S 500K PST 5W TUNE UP CASE GROUND ADJUSTMENT R4 500n 5W N.O. PUSH BUTTON BI B2 S2 11111617 .- 67 I/2V. 11/2V

RI -50,000 ohm pot. Fig. 1. Schematic diagram and parts R2- 270,000 ohm, 1/2 w. res. 133- 100,000 ohm pot. list for the electronic music-maker. R4-500 ohm, 1/2 w. res. R5 -500,000 ohm, 1/2 w. res. C1 -0.01 Aid. mica capacitor C2 -0.02 µfd., 200 v. tubular capacitor The 1G4 -GT tube is the oscillator. Notes C3-0.l µfd., 200 v. tubular capacitor are selected by adjusting potentiometer Rl. S1- S.p.s.t. toggle switch A second potentiometer, S2- S.p.s.t. normally open miniature pushbutton R3, allows the switch (Switchcraft 101 -L) music -maker to be tuned up- either by TI -Audio driver trans. (Triad A -81X) ear or with a piano. T2- Universal output trans. (Stanror A -3823) VI- 1G4 -GT tube When push button S2 is pressed, what- V2-3S4 tube ever note has been selected by the setting B1 -671/2 v. battery (Burgess XX45) of the "Notes" potentiometer, R1, is heard B2-11/2 v. battery (Burgess 2FBP) from the speaker. This push button, when 1- Chassis, 8" x 6"x 41/2" (L.M.B. No. 146) or 8" x it is pressed, 6" x 31/2" (ICA 29444, Bud CU -2109; see text) places the two tubes into 1-3" PM dynamic speaker operation by applying plate voltage. The 1 -Octal socket with 3/4' mounting pillars main "on -off" switch, Sl, controls the fila- 1 -7 -pin miniature socket ments of the two tubes. 3 -2-lug insulated terminal strips 1 -1 -lug insulated terminal strip Tones from the oscillator are amplified 2-Insulated binding posts by the 3S4 tube and fed through an out- I-31/2"x 31/2" piece of speaker grille material put transformer to a small 3" speaker. I- Alignment tool (ICA Type 6161) The terminals labeled 1 -Metal shaft coupling for 1/4' shaft "To External Am- I- Finger -grip knob for 1/4' shaft plifier" may be connected to an amplifier or to the audio stage of a radio when more Total cost of parts, approx. $16.50 volume is wanted. The music -maker operates on two small Parts having the same mechanical and electrical batteries specifications as those indicated may be used. which are mounted inside its case. One of these (B1) is a 671/2-volt B battery which supplies ALIGNMENT TOOL (ICA TYPE voltage to the 6161) 1G4 -GT plate, and to the 3S4 plate and BEND screen. The other (B2) is a 1% -volt A battery which lights the filaments of both tubes.

-METAL SHAFT How It Is Built COUPLING (FOR SET SCREWS I /4' SHAFT) How the "whistler" is built is shown in the photographs and pictorial diagram. Housing consists of an aluminum chassis box 8" long, 6" wide, and 41/2" deep "NOTES" POTENTIOMETER (Bender No. 146). If this specific cabinet (RI) cannot be obtained, a standard 8 "x6 "x31/2" unit (ICA 29444, Bud CU -2109) may possibly be used by rearranging the parts and Fig. 2. Details of the playing handle. perhaps obtaining smaller batteries. A 3 "- diameter hole is cut at one end of the front 58 POPULAR ELECTRONICS

AmericanRadioHistory.Com panel of the box and the speaker mounted then is made in the rod of the alignment behind it. A 32" square piece of loud- tool and the broad round tip on the end speaker grille material covers the hole. of this rod is sandpapered or filed a little The lever -type handle, used to locate the to allow it to slide into the coupling free- notes, is made from a plastic -handled metal ly. Now the setscrews of the coupling are alignment tool (ICA Type 61611 and a tightened, and the job is finished. metal shaft coupling. First, the coupling The "External Amplifier" terminals are a is fastened to the shaft of potentiometer pair of insulated binding posts which can R1, as shown in Fig. 2. A right -angle bend be seen mounted near the speaker. One

BINDING POST

TO 671/2V "8' BATTERY

R3 TUNE UP ADJUSTMENT

Pictorial diagram of the "whistler" showing all of the components except the batteries B1 and B2. August, 1955 59

AmericanRadioHistory.Com of these posts is insulated from the metal If desired, a pointer can be put on the case with the fiber washers that come with arm and the notes written on the top of the post, and the other grounded to the the case with crayon! Now, try a little metal case. Whenever the music -maker is tune -something like "How Dry I Am." connected to an amplifier or radio, the An interesting warble effect can be ob- grounded post must be connected to tained (to break the monotony of sustained ground, or chassis, of the amplifier or notes) by wiggling the arm rapidly back radio. To avoid confusion, a black binding and forth a short distance on each side of post may be used for the grounded termi- a selected note. A broken -note effect can nal and a red post for the other. be obtained by rapidly pumping the push button. Adjustment and Operation For an unusual variation, try building After the wiring has been carefully in- four of these units and form a quartet. Ad- spected and any mistakes corrected, insert just the tonal ranges for soprano, alto, the tubes into their sockets and connect tenor and bass, and persuade some musical- the batteries. ly minded friends to "take over." An ideal Turn on switch Si. Set potentiometer arrangement would be for the four players R3 to the middle of its range, press push to seat themselves around a card table button S2, and swing the "Notes" handle with the units in front of them. If volume from one end to the other. If no sound is insufficient, an auxiliary amplifier may is heard, transformer Ti probably is con- be used, with a microphone placed at the nected backward. This can be corrected by center of the table. The output of each reversing the leads of either the primary instrument could be fed to one input on a or the secondary of the transformer, but four -channel mixer and then to the am- not both. Positive feedback must be prés- plifier, but such an arrangement could be- ent for the oscillator to oscillate. come rather unwieldly. After a little prac- With sound coming out of the speaker, tice, try recording one or two selections on continue to hold the push button down, and a tape or disc recorder. This is the best swing the handle to one end where the way of finding out how the quartet really lowest note is heard. Now, adjust poten- sounds! tiometer R3, by ear or by piano, for mid- There should be many hours of pleasure dle C. Finally, press the button rapidly obtainable with the electronic "whistler." while swinging the arm through its range. And it might lead the way to building the Notes can be played, can't they? A little more complicated musical devices which practice will give the "feel" of knowing will be ,described in future issues of POPU- where to swing the arm for each note. LAR ELECTRONICS. 3D

Interior view of the unit, showing the location of the various parts, and indi. cating how the batteries are mounted. Binding posts are for external speaker.

60 POPULAR ELECTRONICS

AmericanRadioHistory.Com Electronic Analyzer Diagnoses Car Ailments QUICK AND ACCURATE DIAGNOSIS of auto- tested or from any ordinary 110 -volt motive engine ills is possible with an elec- source. The leads are long enough to tronic instrument developed in the research laboratories of Socony- Vacuum Oil Company, Inc. This instrument has now been made available for general public use. Known as an engine analyzer, it will be manufactured and sold by the Allen B. Du Mont Laboratories, Inc., Clifton, N. J., under a licensing agreement recently con- cluded between the two companies. Weighing less than 60 pounds, the engine analyzer "televises" engine performance through a cathode -ray tube on an oscilloscope screen. Connected to an automobile ignition system by two lead wires, it gives simultaneous pictures of the behavior of each cylinder in an operating engine. It can diagnose faults in a car ignition system in less than one minute. permit road testing with the instrument The analyzer detects virtually all igni- placed on the floor of the car ahead of tion system troubles. For example, burned the front seat. Its use in road testing distributor points -one of the chief causes makes it possible to detect engine faults of poor engine performance -are easily that show up only under particular operat- identified by the analyzer. In addition, it ing conditions. will diagnose pre- ignition faults as well In a recent experiment, the analyzer as troubles caused by noise and vibration proved that only five out of 35 cars chosen or combustion knock. The instrument may at random were in top running condition. also be used to check ignition timing and In one car, it detected a short circuit that operation of intake and exhaust valves. In had eluded mechanics for months -caused all, picture patterns depicting about 65 periodically by the float on a gasoline gauge different engine ailments have been ob- when it reached a certain fuel level. served and identified. The instrument will be listed by Du Power for the engine analyzer may be Mont as the "Type 901 Cathode Ray En- supplied by the battery of the car being gine Analyzer." --

marily for strong signal areas. For addii- Indoor Rotating Antenna tional information, write to Walsco Elec- DESIGNED FOR METROPOLITAN and subur- tronics Corporation, 3602 Crenshaw Boule- ban area reception, the Walsco "Star" in- vard, Los Angeles 16, Calif. door antenna contains a built -in electronic rotating and tuning control. Turning the control changes the directivity by automatically selecting the correct combination of elements for a sharp, clear picture on each channel. External interference is reported noticeably reduced or elim- inated without moving or twisting to find the best angle. The three different -size receiving elements on the new Walsco "Star" are tuned to pick up v.h.f. or u.h.f. stations in opposite directions and on widely separated channels. Style -wise, the antenna's ceramic base colors of lime, green and sand were chosen for their ability to blend with all furnishings. Similar in appearance is the economy model without the electronic tuning. This is the "Starlet" model, recommended pri-

August, 1955 6I

AmericanRadioHistory.Com FORMING BLOCK BASE 3/4"X 3/4" X 2 1/2 (MAX.) 3/4"X 3 3/8 "X.5 5/8" BEVELLED BACK 45°

-t 3/8"

HOLDING SCREWS ALUMINUM STRIP 18 GAUGE STARTING xi 8, 3/4' RD. HD. LINE 1/2" X 3 5/8"

t`I`4C',y\tI\i1a\i+\ ,.- 'Ob. . r ir-gb. Ji Makes Solder Gun Tips

ASOLDER gun is worth its weight in U- 235 -that is, if its tip is in good By HARVEY POLLACK shape and ready to go at all times. Since most solder gun tips soften and corrode after a few hours of use, with wear occur- copper wire will last indefinitely at the ring at the point of solder application, spare rate it is used in the process. tips should always be available at a mo- To make the jig, cut the rectangular ment's notice. base (A) preferably from hard wood, like Having wearied of buying new tips at maple or oak; prepare the forming block the prices asked, the writer designed the (B) by cutting it to size and then beveling home -made tip jig shown here from a few scraps of wood and a small strip of 18- gauge aluminum. The jig fabricates tips of Outline and dimensions for jig are shown at uniform size quickly and without fuss; best top of page. Parts designated by code of all, one small roll of No. 10 soft -drawn letters are explained in text. Be- low: first step in forming new solder gun tip, using jig.

62 POPULAR ELECTRONICS

AmericanRadioHistory.Com it at an angle of 45 °. Hacksaw and file an aluminum strip (C) to size. Drill and coun- tersink it for two 1/2" No. 6 wood screws, flat -head. Secure the strip (C) to the side of the forming block (B) as shown in the illustrations using these wood screws; in so doing, let the strip project downward toward the base a distance of about 1A6" beyond the bottom of the forming block. This projection will fit into a groove chiseled into the base to prevent the strip from bending while the tip is being made. The right end of the strip projects exactly 1%" beyond the end of the beveled forming block. Screw the forming block to the base after having chiseled out a recess for the bottom edge of the aluminum strip. By sinking the strip in the base this way, a degree of rigidity is obtained that is of Second step in making a tip or the sol- great help in using the jig. dering gun is to bend the 71,4" strip of As a final step, screw two round -head wire back over the metal icrming piece. wood screws into the base near the aluminum strip, separated from the latter by the diameter of the No. 10 wire to be used. These holding screws (D) are allowed to protrude above the base about 1/4 ". To use the jig, first cut a length of wire exactly 7'ii " long. Slide the end of the wire between the strip and the holding screws to the starting line (E), and bend the wire around the end of the strip. Using a pair of gas pliers or long -nose pliers, squeeze the wire around the bend close to the strip on each side, and then continue to bend it by hand so that it follows the contours of the forming block. Place the clamping nuts (that come with the gun) on the wire. Make sure the threads face the right way to permit fastening to The Bp has been shaped. Noe how it the gun. Then bend up 1/4" of each end of follows the contours of the forming block. the tip. Insert into the gun's retaining holes, and tighten the clamping nuts. The Below, soldering gun with iew tips new is solder tip now correctly mounted. ready for assembly. End of tips that fit Tin the tip, and the gun is ready for into gun "barrels" must be bent up slight- use. 30 ly after the clam3ing nuts are attached.

August, 1955 63

AmericanRadioHistory.Com The $1.ÓD Signal Generator

ANYONE with a small piece of wood, a By FRANK H. TOOKER buzzer, a couple of flashlight batteries, and $1.60 can build a modulated signal generator that can be used to align receivers, Undoubtedly the simplest tunable test r.f. circuits, and do many other things a modulated signal generator costing 20 to signal generator yet devised for 100 times as much can do. How this inexpensive little signal source the novice ham and experimenter can be made is shown in the photograph and wiring diagram. Only five parts are needed. These are arranged on a piece of -build it and see for yourself % " -thick plywood measuring about 4" x 6 ". Connections to the dry cells are made by driving four brass wood screws into the board until their heads are in contact with the brass cap on one end of the cell and the will not be used, so clip the fine wires lead- bottom of the zinc can on the other end. ing to it and remove the cardboard sleeve The screws are spaced close enough to per- by slipping it off the end of the coil form. mit moderate pressure for good electrical Wind on a new primary consisting of about contact. A simple bracket holds the cells 10 turns of ordinary No. 20 plastic hookup in place. Wires soldered to the slots of the wire over the bottom end of the tuning coil, screws connect the cells in series and make and connect the ends to the terminals from the connections to the coil and buzzer. which the fine wire primary leads were The 0.25 -pfd. fixed capacitor must be con- clipped. Locate the parts on the board (the nected, as shown, across the buzzer con- arrangement isn't at all critical), make the tacts. If this capacitor is connected across few electrical connections shown in the di- the buzzer winding or across the buzzer as agram -and the unit is finished. a whole, the unit will not operate. The Miller 20 -A r.f. coil is a standard How If Works part which has been slightly modified. The It is a basic principle in electricity that original coil has a primary winding consist- when a current flowing through a coil of ing of a few turns of very fine wire wound wire -especially one having an iron core on a short adjustable sleeve. This primary such as the buzzer winding-is suddenly

This photo does not show the toggle switch included in the pictorial and wiring schematic. It is obviously required to turn the circuit off after use.

AmericanRadioHistory.Com interrupted, a voltage much higher than nary household buzzer may be substituted the battery voltage will appear momen- if necessary. In this case, additional batter- tarily across its terminals. This induced ies may be needed. Using a different buzzer voltage is caused by the abrupt collapse of does not affect the tuned circuit, so the coil the magnetic field around the coil. Use is and variable capacitor need not be altered. made of this principle in the present signal If the sound from the buzzer is too loud generator. for the strength of its tone to be distin- A rapid succession of inductive voltage guished easily in the speaker, enclosing kicks is induced across the buzzer winding either the buzzer or the entire generator by the rapid making and breaking of the in a cotton -padded cardboard or wooden winding current due to the operation of the box (not metal) will decrease the sound buzzer contacts. The current from these coming directly from the buzzer without voltage kicks flows in sharp, rapid pulses disturbing the r.f. output. through the primary coil, where it excites If a short antenna is connected to point the tuned circuit and causes it to oscillate (A) in the wiring diagram, this little signal at a frequency determined by the setting of generator will make an ideal code practice the variable capacitor -in the present setup oscillator, since its signals can be transmit- -at any desired frequency between 540 ted from one room to another without wires and 1700 kc., the standard broadcast band. and can be picked up on any broadcast set! Oscillations of the tuned circuit are auto- The antenna should be no longer than nec- matically modulated by the buzzer tone, so essary to produce a good tone in the speak- all that is necessary when touching up the er when the receiver's volume control is front end of an a.c. -d.c. set, for instance, is well turned up. When using the generator to turn on the signal generator and set in this manner, connect the telegraph key its variable capacitor somewhere near the in place of the switch shown in the di- high end of the band. Then tune the re- agram. j- ceiver until the buzzer tone is heard coming from the speaker. Adjust the trimmers on the receiver for loudest output. Generally, O TO RECEIVER CI O.25Nfd. r - no direct connection between the receiver PRIMARY _t_ (SEE TEXT)i COUPLING and signal generator is needed. Standing COIL the two fairly close together is sufficient. (SEE TEXT) When tighter coupling is needed, wrap an BUZZER insulated wire two or three turns around WINDING LI the lead to one side of the tuned circuit, BI with the other end of the wire lying near or connected to the receiver's loop or antenna SI-IIII TUNING terminal. SP.S.T 3V COIL The buzzer used in the generator shown in the photograph is a 1000 -cycle Wiring schematic of the generator. For de- type gen- tails on the see instructions in text. erally used for code practice, but an ordi- coil,

Pictorial wiring drawing of the generator. As men- Jill/II///// / /// tioned in the caption on the facing page, this drawing includes the toggle switch not shown in photo.

August, 1955 65

AmericanRadioHistory.Com CARL flY By

JOHN T. FRYE The two boys climb a hill, then

talk about kinds of TV antennas and how they work

THE HOT AUGUST SUN beat down on he removed a thick paper -wrapped sandwich the two boys climbing up the steep path. and slowly pulled out the toothpick thrust Lanky, athletic Carl Anderson scarcely through it. breathed hard as he forged steadily up the With a snarl of mixed hunger and rage, hill; but behind him his overly plump chum, Jerry leaped to his feet and charged up the Jerry Bishop, puffed like a steam locomotive path toward his tormenter. Carl barely had as he toiled along the steep ascent. In spite time to toss the sandwich back into the ham- of his noisy effort, Jerry kept falling farther per and scramble upward out of Jerry's and farther behind, and finally he came to a clawing reach. The latter was so incensed full stop and collapsed in the shade of a huge by the horrifying prospect of Carl's eating boulder beside the path. all the lunch that he did not slacken his pace "How come you're dropping anchor there, and the two boys arrived at the top almost Blimp Boy ?" Carl called down. "We've still neck and neck. got a quarter of a mile to go to the top." "You made it!" Carl congratulated, as he "I can never make it," Jerry gasped flung himself at full length on the thick feebly. "Go on without me. Just say my grass beneath a tree. spirit was willing but the flesh was weak. For a minute, Jerry stood over him with Leave me a dozen sandwiches or so to make his face still wearing its menacing scowl, my last moments comfortable." but then as he looked about and realized he "Not a chance!" Carl interrupted harshly. had actually reached the summit, his round "I coaxed you on this hike to sweat some of countenance broke into a pleased grin and the fat off you, and off it comes-one way or he sat down abruptly beside his friend. another. We agreed to eat, you will remem- "We better cool off a little before we eat," ber, when we got to the top of the hill. Well, Carl suggested. "It certainly is a wonderful if I've got to go on by myself, I'm going to view, isn't it ?" "It sure is," Jerry agreed, with his head buried in the picnic hamper. "Now that we've cooled off for at least a couple of hundred seconds, let's eat. Do you want your tenderloin sandwich with or without mus- tard?" There was little conversation for the next few minutes as the boys waded through the assorted sandwiches, hard -boiled eggs, and fresh fruit that Carl's mother had provided. Finally, though, when they were munching their chocolate bar dessert, Carl said lazily : "Jer, look at all those TV antennas down there. Hardly two of them are alike; yet they're all intended to receive the same sta- take the lunch with me and eat it -all of it tions. How come there are so many different -up there just as we planned." kinds ?" "You wouldn't dare!" Jerry cried, with Jerry pillowed his head on his clasped the quick instinctive anger of a hungry ,dog hands and stared up at the fleecy white who sees his bone suddenly snatched from clouds drifting across the blue sky overhead. him. "To answer that properly really takes a lot "Oh no ?" Carl said tauntingly, as he of doing," he said slowly. "You almost have squatted on his heels and opened the lunch to go into the subject of how TV antennas basket he was carrying. Very deliberately, work." 66 POPULAR ELECTRONICS

AmericanRadioHistory.Comr i: i:.ü;lx ifllá«ertrUlkIfA1-f;Yli line would be "So let's go into it," Carl promptly urged. "And I guess a 52 -ohm coax and you think you've got worse "I've got the time, have information." "It can be done, and some receivers the is much "When TV broadcasting first started," a 52 -ohm input for this line, but it "the receivers were invariably more expensive than twin -lead and has a Jerry began, of dry close to the transmitter, and the engineers much higher loss than a good grade old standby short -wave twin -lead. It was easier to change the dipole simply adapted the in- receiving antenna, the half -wave dipole. so that its impedance would match the This is simply a conductor which is an elec- expensive 300 -ohm flat line." long at the frequency "How did they cut that caper?" trical half -wavelength a half being received and which is cut in two at the "Just by placing another conductor that each half feeds into one part wavelength long three or four inches above middle so ends to the of a two- conductor feedline, such as a twist- the dipole and connecting its ed pair, coaxial cable, or piece of twin -lead. In radio work, the conductor is usually wire; but since a half wave is only a matter of a few feet on the TV frequencies, the TV antenna was made up of a couple of pieces of aluminum tubing secured to a center block of insulation." "I don't see anything like that down there," Carl remarked as he raised himself on an elbow and looked down at the rooftop antennas. "No, that simple antenna didn't last long because it had several serious faults. For one thing, it had a front-to -back ratio of 1 to 1. By that I mean its horizontal reception pattern looked like a figure '8.' While practically no reception was had off either outside ends of the dipole. This changed the end of the dipole, identical reception lobes simple dipole into a 'folded dipole,' with sev- extended out from either side. If you called eral important advantages. For one thing, one side the 'front' of the antenna and point- the antenna impedance was quadrupled so ed it at a station, another station at the rear that it was almost an exact match for the would be equally favored in reception. As 300 -ohm line. Secondly, the frequency re- more and more stations came on the air, sponse of the folded dipole is much wider forcing many to share the same channel, than that of the simple dipole." this became a serious defect. Secondly, the "Wait up!" Carl commanded. "What's output impedance of the dipole is about 72 this jive about widening the frequency re- ohms, an inconvenient value for matching sponse?" to low -cost, low -loss transmission lines." "The dipole delivered maximum received on the channel for "I don't dig this ' impedance -matching signal strength only business as well as I might," Carl admitted. which it was cut. Signals on adjacent chan- "Every piece of equipment that generates, nels excited much less response in the an- carries, or receives r.f. currents has a cer- tenna, and signals from channels still far- tain amount of built -in opposition to the ther removed from the antenna's resonant flow of those currents that is called 'im- frequency produced still less response. Since pedance,' " Jerry explained, beginning to en- the antenna responded only to signals close joy his role of lecturer. "In order to transfer to its resonant frequency, we say it had .a the maximum amount of power or signal narrow bandwidth. The folded dipole re- from one piece of equipment to another, sponds much more strongly to signals on their respective impedances must be equal adjacent channels, so we say it has a wider or 'matched.' If the TV antenna is not bandwidth. Catch ?" matched to the feedline and if the feedline "Roger. With a wide -band antenna, you is not matched to the receiver, you not only can receive several channels on the same lose a lot of signal but the mismatch is antenna. With a narrow -band job, you can likely to generate annoying ghosts in the receive only one channel well." picture. Most TV sets are built with an "I do believe you're getting brighter!" antenna input impedance of 300 ohms. Low Jerry said sarcastically. "At any rate, the cost and efficient twin -lead designed to folded dipole still did not have all the an- match this also has a 'surge' impedance, as swers. Especially, it did not prevent receiv- it is called, of 300 ohms. But if you have to ing a station just as well off the back as the feed a 72 -ohm half -wave dipole antenna into front. To correct this fault, TV design en- the end of this 300 -ohm feedline, you have gineers borrowed the yagi antenna radio a 4 to 1 mismatch." (Continued on page 116) August, 1955 67

AmericanRadioHistory.Com - THE TRANSMITTING TOWER

HERB S. BRIER ,W9EGQ

It is with considerable personal pleasure that I miners, artists, college professors, generals, am able to introduce Herb S. Brier, W9EGQ, to the privates, missionaries, school readers of POPULAR children, milk- ELECTRONICS. Having men, plumbers, and politicians. From among worked with Herb for several years, I am aware of his great interest the 65,000 overseas, you can add kings, in the novice ham radio ranks. princes, His many articles and columns also attest to his and dukes to the list. They engage desire to aid and assist newcomers in obtaining in two -way communication between them- radio amateur licenses. The Editors of POPULAR selves via their own radio stations, purely ELECTRONICS believe that Herb's work should be as a personal pursuit, without thought of brought to the attention of a wider audience and pecuniary gain of any sort. They operate are pleased to welcome him to our staff. Readers in special bands of frequencies throughout are encouraged to address inquiries and items of the radio spectrum ham radio interest that have been set aside to Herb, simply addressing for their use by them to his attention % POPULAR ELECTRONICS, international agreement. 366 Madison Ave., New York 17, N. Y. The Transmitting Tower will appear o.p.f. monthly in POPULAR ELECTRONICS, and it will be devoted to amateur radio. Of course, many of its readers will already have their SHAKESPEARE defined Cleopatra's fas- licenses, but we are anxious to have the cination as follows: "Age cannot wither rest of you join us; therefore, this first col- her, nor custom stale her infinite variety." umn will outline how you may obtain your By a similar definition, amateur radio is license. the Cleopatra of hobbies. It thrills the As you will see, you do not have to be newest beginner and continues to fascinate an electronic wizard to obtain a license. men and women who have been radio ama- Even if your electronic knowledge does not teurs for 40 years or more. extend beyond the ability to tune a tele- Among the more than 130,000 licensed vision set or an automobile radio, you can amateurs in the United States are doctors, quickly qualify for your license. Yet, I lawyers, merchants, scientists, prize fight- repeat, amateur radio is not a hobby you ers, nuns, actors and actresses, invalids, coal will soon outgrow. In fact, the more you learn about it, the more fascinating it becomes. The Federal Communications Commis- sion, Washington 25, D.C., issues amateur licenses in five grades-Novice, Technician, Conditional, General, and Extra Class. If you are a citizen of the United States, you are eligible to apply for one of them, regardless of your age, sex, or practically any physical disability. Furthermore, it will not cost you a penny. Classes of Licenses Here is a brief description of the various classes of amateur licenses and the privileges that they grant. The simplest amateur license to obtain Roger Horned, W9ZSW, Terre Haute, Ind., has a is the Novice license. typical low -power It will be issued to ham station built around "war any citizen of the United who surplus" radio equipment. Roger started out as a States has novice (36 states) and now has a General Class not previously held an amateur license and license. Doctor Horned is well known as the co- can send and receive the radiotelegraph discoverer of the new antibiotic, seromycin (cyclo- code at a speed of five words per minute serine): this drug has proven effective in fighting and pass a simple written examination. The deep -seated infections and combating tuberculosis. examination consists of about 20 multiple- 68 POPULAR ELECTRONICS

AmericanRadioHistory.Com are choice questions covering elementary ama- Technician Class license holders teur radio theory and Novice regulations. granted full amateur privileges on the ama diagrams are required, and 74 teur bands above 50 mc., except on the No circuit the is a passing grade. 144 -mc. band. These privileges include license authorizes code operation in right to use phone, code, teletype, and other This power segments of the 3.5 -, 7 -, and 21 -mc. amateur forms of emission with a transmitter bands and either voice or code in a segment up to 1000 watts. The disadvantage to the of 144 -mc. band. A crystal -controlled license is that the normal communication the sim- transmitter is required, and its power input range on these bands is limited. With must not exceed 75 watts. The latter is not ple equipment, it is about 50 miles. Un- much of a handicap. Few Novices use more usual conditions, which occur fairly fre- than half this power, but they still talk to quently, especially in the warmer months, amateurs all over the United States and do extend ranges many times for periods make an occasional foreign contact. ranging from a few minutes to several effect, the Novice license is a learner's hours. In all am- permit. It is issued for a one -year period The General Class license grants and cannot be renewed. Therefore, the li- ateur privileges on all amateur bands. It is censee must qualify for a higher class ama- obtained by passing a 13 -wpm code test teur license within that time or leave the and the standard amateur written exam- air. Most qualify for another license within ination described above at an FCC examination point. The Conditional Class license grants the same privileges, and it requires passing the same type of examination. How- ever, it is issued by mail under conditions to be described a bit later. Because two ycars of licensed amateur experience is one of its prerequisites, the Extra Class license is of no immediate importance to prospective amateurs. Other prerequisites are a 20 -wpm code test and a very comprehensive written examination. Obtaining this license is a matter of pride, because it grants no special privileges. Technically speaking, the amateur oper- Bill (W3WRC) and Louise (W3WRE) Moreau, John- ator and station licenses are separate. But ston. Pa., constitute one of the many husband and they are applied for on the same form and wife ham teams. Starting out as Novices with a are issued together on a single license card. 35 -watt transmitter, they are now using a WRL only a licensed amateur op- exists as to who will Furthermore, "Globe Scout." Rivalry will be issued an amateur station work the 48 states first with General license. erator license. call a few months. All other classes of amateur In the United States, all amateur for five -year periods signs, except Novice, consist of the prefix licenses are issued from and are renewable. "W" or "K," followed by a number 1 0 or three additional letters. The Technician Class license also requires to and two code test, Novice calls contain the letter "N" between passing a five -word -per- minute is which is the the prefix and the number. The "N" but its written examination, when the Novice qualifies for a "standard" amateur examination, requires removed theory and regula- higher class license. a good grasp of amateur Learning exactly what you must know is tions, plus the ability to draw schematic diagrams of basic amateur circuits. (Continued on page 102)

These members of the Mar- tinsville, Ind., High School Ra- dio Club meet twice a month during school periods. Meet- ings are held in the science laboratory where the club station W9FXY is installed. Hams shown in this photo include WN9NPS, W9UPJ, WN9NFB. WN9NCK, and W9DUD who is the High School club sponsor.

August, 1955 69

AmericanRadioHistory.Com AMA-TOU with Roger

11 -YEAR sunspot cycle is of pri- of the rise in MUF's has resulted in im- THEmary importance to DX radio transmis- proved conditions on the 14-mc. band, and sion and therefore is of special interest to should be particularly noticeable during the short -wave listeners. "Sunspots," which coming fall and winter period on both the appear as black spots on the sun, are be- 14 -mc. and 21 -mc. bands. lieved to be gigantic temporary craters caused by eruptions on the sun. Sunspot I WOULD APPRECIATE receiving reports on numbers, calculated on the basis of the DX heard, particularly on new stations in number of observed sunspots and their the less frequently heard countries, with area, are found to vary from a minimum frequency, time heard, and any other in- to a maximum and back again to a mini- formation of interest regarding them. mum over periods averaging 11 years. Here are some reports that have been During years of low sunspot numbers, the received from readers on DX stations. All MUF's (maximum usable frequencies) are times are based on EST, 24 -hour clock sys- low and transmission conditions on the tem. higher frequency bands, such as the 28 -mc. North band, are poor. The hours of usefulness for and South America long- distance transmission of lower bands, Corn Island- YNOYN, 14.12 mc., was oper- such as the 14 -mc. band, are considerably ated for a short time from Corn Island, off reduced. As the sunspot numbers rise, the the east coast of Nicaragua, by a DX expe- MUF's also rise, resulting in better trans- dition composed of WOEIB, WSAIW and mission conditions on the high frequency YN4CB. YN{ YN was also operated mobile bands until, during years of sunspot maxi- marine from the ship while they were on mum, DX conditions on the 14-, 21 -, and the way to the island. If you heard this 28 -mc. bands are at their peak. one, reports may be sent to WOEIB, Wal- We are now in a period of low sunspot ter J. Klassen, 110th & Antioch, Lenexa, numbers, but having passed the minimum Kansas. (Tom Gallagher, Fla.; Hugh Clark, over a year ago, in May, 1954, the sunspots Calif.) are on the way up, and we can look Greenland - U. S. personnel stationed in forward to constantly improving DX condi- Greenland are now using KG1 calls instead tions during the next five years. The effect (Continued on page 122)

AUGUST DX FORECAST FOR 14 -MC. BAND In these forecasts, based on information In Eastern & obtained from the Na- From USA la Western USA tional Bureau of Stand- Central (PST) (EST) ards, the 24 -hour clock system has been used. Central and South America 0600 -2200 0600 -2100 The hours from mid- Best 1700 -2100 night until noon are shown as 0000 to 1200, Europe and North Africa 1500 -1900 1400 -1600 while the hours from 1 p.m. to midnight Central and South Africa 1600 -1800 1400 -1600 are shown as 1300 to 2400. EST represents Far East 0600 -0800 0500 -0800 Eastern Standard 2100 -2400 Time; PST is Pacific Standard Australia and New Zealand 0000 -0300 Time, three 0500 -0800 hours later than EST. 0600 -0800 2200 -2400

70 POPULAR ELECTRONICS

AmericanRadioHistory.Com Tuning the Short -Wave Bands

By HANK BENNETT

by contributions from HE SUMMER vacationing period is per- which is supported stage now and the American people through "Crusade for haps at the most active which is slow. Du- 'ng the Freedom," its fund -raising arm, and DX'ing, as a rule, what its title suggests and or roughly fr :_ June does just about summer months, was organized in December through Labor Day, many DX'ers take time implies. RFE of their hobby in order of 1949 to conduct an on- the -spot campaign out from the pursuit against the Com- of the hundred and one things of psychological warfare to take care in Czechoslovakia, Poland, that must be done around the house and munist regimes weather, with the light- Hungary, Roumania, Bulgaria, and Albania, yard. The summer all countries that are strate- ning disturbances and the outside noise specifically, mowers and other power gically placed in the battle for men's minds created by power Europe. makes listening more of a chore than now being waged in tools, The station went on the air in July of a pleasure. Then, too, many of the DX'ers earphones, and 1950 with one transmitter located near do their listening through began warm, humid weather, this does not Frankfort in West Germany, and in the for a total of 10 hours per add to the comfort of listening. broadcasting with the advent of week. It has been on the air continuously Next month, though, ever since, and now has 21 short- and me- cooler weather and the lessening of static, into serv- dium -wave transmitters located throughout many receivers will again be put and Portugal broadcasting on the various s.w. bands West Germany ice. New stations 430 hours of programs a week to its six will be heard; many others will be noted Some will have in- target countries. on new frequencies. RFE's main broadcasting studios are in creased their power and others will have Germany, You, the Munich, in the American Zone of made extensive program changes. the Iron Curtain, column possible, will where exiles from behind DX'ers that make our Germans, Americans, and personnel from resume sending in frequent reports to us to present other countries are stationed. Additional and we, in turn, will be able programs are tape- recorded from the Radio our readers with more information. The to be better Free Europe studios in New York. coming DX season promises grew judging from the increasing The primary purpose of RFE, which than average, of employees in the begin- sunspot activity. from a handful For this month, we present an article written by Mr. Ben Adams, of New York City, concerning Radio Free Europe. It is our hope that you will enjoy this article, which seems to cover the subject very thoroughly and interestingly. Radio Free Europe You've no doubt heard a great deal about Radio Free Europe in the past several months because of its fund -raising campaign, which has, appropriately enough, gone to the American radio and television audience for assistance. In the event that you've also wondered about it and felt the need of a little more information or background, please allow me to offer the following : Radio Free Europe is a division of the National Committee for a Free Europe, George Cox, of New Castle, Delaware. August, 1555 71

AmericanRadioHistory.Com =[p,: .... i; : --+i.Jii;a}y:`ci SO' iA::q±,91111,.i.:MM!rn;,l.-.4r,.,;,p.

ping to more than 1000, is to sustain the not only the nations we hope seek to help; it of captive peoples behind the Iron serves the best interests of the United Curtain of regaining their national freedom States." and their individual liberties, and to encour- age the eventual restoration of these peo- Now FOR ples to the THE LATEST from the DX scene; free world. all times shown are Eastern Standard, In order to carry out a program of such based on scope, the 24 -hour system. Radio Free Europe realized early AZORES -Ponta Delgada, that a new approach, 11925 kc., is again utilizing new propa- heard during the summer months on this ganda techniques, had to be adopted for frequency its at 1400 -1500. Evidently the 4867 target areas. In a short time, experi- channel is the winter mentation proved that outlet. (Legge, Va.) RFE could most ef- BRAZIL - Radio Brazil Central, Goiania, fectively deliver its message -and at the Brazil, same is testing two new transmitters on time promote American ideas, and 9755 and 11815 kc. Although understanding of the these stations American people -if it have not been heard often, they are noted spoke with the voice and authority of exiles late evenings with American from behind the Iron and Latin - Curtain. To do this, American music and announcements in RFE developed a network of six stations, Portuguese and the Voices German. (Parker, N. H., of Free Czechoslovakia, Free NNRC). The "Ministerio da Educacao" Hungary, Free Poland, Free Roumania, out- Free let in Rio de Janeiro is being tuned around Bulgaria, and Free Albania. On each 1525 and 1945. (Ferguson, of these stations, freedom N.C.) -loving exiles from CEYLON-Colombo can be heard in English the captive countries of their birth now on 11770 and speak to their 7190 kc. at 2000 -2300 and on people in their own idiom. 9520 and 6006 kc. at 0600 -1200. They pre- Chosen on the basis of professional capabil- sent a news relay from the BBC at 0930 on ities and devotion to the cause of freedom 9520 kc. (Roemer, Ky.) and democracy, RFE exiles write their own CUBA -COBZ, Radio scripts, prepare Salas, Havana, has their own programs, broad- moved from 9025 to 9015 kc. cast in their own styles. ECUADOR-HC2RL, Guayaquil, on 6635 kc., This is the general policy under which was noted around 2200. RFE operates. This station is believed to operate Tuesdays only at 2100- To break it down further, RFE's pro- 2300. (Legge, Va.) New stations operating grams cover a range of subjects equal to al- include Radio Ondas Nacionales, most any radio Quito, station in this country. The HC1GT, 200 watts, on 5955 and 1380 kc.; American scene and world news are, of "Radio Universal, HC2UM, course, Guayaquil, 9550 included in programs of many types. kc., 250 watts; Radio Ecos del Agro, HC2JJ, World news is broadcast around the clock, Quevedo, 3960 kc., 200 watts; every hour, Radiodifusora since the truth is a precious Fatima, HC3CD, Loja, 5975, 400 watts; and commodity in the war of words. Special Radio Cultural Religiosa, programs HC6JX, Banos, are designed for young people, 4920 kc., 200 watts. (World Radio Hand- workers, farmers, intellectuals, women, sci- book) entists, military men, and even Commu- FINLAND -The newest schedule from Hel- nists. Religious news and services are sinki, Finland, which broadcast runs until September to listeners of all faiths. Culture 21, includes news in English to North Amer- and comedy, drama and music, satire and ica at 2300 -2315, and to quiz Europe and South shows, forums and interviews are also America at 1430 -1445. Both programs are included in a schedule designed to build heard on weekdays (no Sundays) the biggest and on 01X5, broadest of audiences. 17800; 01X4, 15190; and 01X2, 9550 kc. Of primary importance is RFE's practice Effective September 23, 1955, to March of telling its listeners what goes on within 20, 1956, the transmission to Europe and their own countries. Refugees are inter- South America will be heard at 0430 -0550, viewed on conditions in their countries. to North America at 0600 -0755. Researchers constantly add new informa- GREECE The latest schedule of Radio tion to their files, piecing - it together and Athens is as follows : 9607 kc. -0200 -0315 analyzing it into the most accurate picture daily to Cyprus, 0400 -0500 daily, except Sun- of conditions that is possible. As to the day to Egypt, 0530 -0800 daily to Cyprus, effectiveness of RFE in its nearly six years 1100 -1200 daily to Cyprus, and 1300-1330 of operation, President Eisenhower recently daily to Northwest Europe; 11718 kc. -1030- had this to say: 1045 daily to Russia, 1215 -1245 daily to "Through Radio Free Europe, men and France, England and Mariners; 7142 kc.- women, who might otherwise have suc- 0830 -1015 daily to the Balkans, 1400 -1455 cumbed to the philosophy that it is good daily to Northwest Europe. (Buettner, Ger- to be slaves, still keep alive the spark of many) freedom in their hearts. This work serves (Continued on page 119) 72 POPULAR ELECTRONICS

. , fÍYÌIí{iliYylYaHM'iil. AmericanRadioHistory.Com ii9(ir«K'rirlílègBlrgibl1.414TÌM04IIIdi -ivv:tint. m.7,77F-wtr r- a '74"7",

experimental license may operate R/C equipment on all authorized frequencies above 53 mc. Special authority may be obtained to operate R/C equipment in the industrial, scientific,, and medical bands (13.554 to 13.566 mc., 26.958 to 27.282 mc., 40.660 to 40.700 mc., 890 to 940 mc., 2400 to 2500 mc., and 5775 to 5925 mc.). In the past, non -amateurs were permitted to operate R/C equipment on the industrial, scientific, and medical bands if they were British subjects, over 16 years of OFTEN. IN THE PAST, we've sounded age, and holders of a private commercial off on various and sundry subjects license which cost $10.00 annually. Whether apropos radio control. Transistorization, the new regulations to be evolved will be miniaturization, reliability-all have re- as lenient as those governing the Citizen's ceived our scholarly treatment; and more band in this country remains to be seen. often than not, we've arrived at the con- clusion that not enough is being done to JUST OUT is a de luxe model airplane kit adapt the various advances made in the that has been specially designed and engi- electronics field to the hobbyist. neered for radio -control flying. It is the "Live Well, lest you get the idea that all we Wire Champion," built to something called do is sound off, we have some projects "R /C Scale" -which is a new term in- cooking that should help electronic hobby- vented by the manufacturer, the deBolt ists get their feet good and wet in some Model Engineering Co., of Williamsville, of these new techniques. This issue, for N. Y., the idea being that the model was example, contains a step -by -step construc- designed for optimum R/C flying first and tion article on "Printed Circuitry for R /C" then made to look like a full -scale model. starting on page 74, by the well -known The model is patterned after the Aeronca R /C'er Paul Runge. His technique for "Champion" and is especially suited to .15- making printed circuits is just one that we size engines (or a well -throttled .19). The would like to advance for your experimentation. Future issues of POPULAR ELECTRON- ICS will contain articles on the etching method as well as a roundup of printed circuit kits available to electronic hobbyists. So far as transistorization is concerned, we'll soon have an article for you on a transistorized R/C receiver.

DO IT, why not yachtsmen? SHARKS ..+ion, We've all heard about or seen pictures of little pilot fish that swim around in bare model weighs 30 ounces, leaving over the if you like. front of sharks, and now comes a yachts- 2 pounds for R/C equipment man who has a radio -controlled model of Wing span is 56 inches. which always precedes his motor cruiser scheduled him into his berth. This we think is a THERE ARE LOTS Of flying meets gesture that some for R/C fans in August. Texas has the clever and whimsical Antonio full -size yachtsman might like to Alamo Regional Contest in San other C. C. Perkins try. We pass it along for what it's worth. on the 6th and 7th; write to at 235 W. Drexel, San Antonio 10, Texas, An- IN RESPONSE to questions by some of our for further information. The Fifth readers, we've queried the Canadian De- nual Metropolitan Championships for R/C partment of Transport, Telecommunica- will be held on August 7th at Staten Island, tions Division (equivalent to our FCC), on N. Y.; contact Sal Cannizzo of 293 Mary- its rules governing the radio control of land Ave., Staten Island 5, N. Y., for data models, etc. According to the Honorable on these. New England R/C Champion- G. C. W. Browne, Controller of Telecom- ships are scheduled for August 14th in Mass., with John K. Ross of 23 munications : "The question of licensing Beverly, such equipment is now under review, and Lantern Lane, Wellesley Hill, Mass., acting until a decision has been reached no further as Contest Director: The Ninth Annual licenses are being issued. In the interim, Mid- Western States Model Airplane Cham- however, operation of approved radio -con- pionships will be held on August 14th at trol equipment is being permitted on a Indianapolis, Ind.; the C. D. is Roland C. temporary basis." Rhein, Allison Div., General Motors Corp., Holders of a Canadian amateur radio Indianapolis, Ind. Good luck! 73 August, 1955

AmericanRadioHistory.Com i. .. .. =-1 ii... 41 Printed Circuitry For R/C

First, on a sheet of paper, make a layout Transfer the paper pattern to the copper of the proposed printed circuit board, uti- side of the laminate. Use a punch to lo- lizing actual parts to determine final size. cate the component terminal positions.

WITH THE rapid adoption of printed chloride which etches away the exposed circuitry in the electronics field, many copper and leaves the pattern covered by R/C fans have attempted to devise simple the ink. Home experimenters who have ways of making their own printed cards tried this method prefer it to the silver ink for their favorite receivers and transmit- technique. ters, with varying degrees of success. A number of methods have been used. Stripping Technique One that has found a moderate following A third method of making printed cir- uses silver conducting ink which is applied cuits is known rather simply as the "Strip- with pen or brush on ordinary %6" linen ping Technique." It is obvioúsly not intended base material. However, the technique of for mass production or for applying very complicated the ink requires more of an artis- circuitry. However, with a little practice, tic touch than many R/C fans will ever multitube receivers and transmitters develop. may Also, this type of printed card quite easily be put on small sheets of copper must be handled with care so that it is not laminate. The stripping technique does not accidentally scratched and the circuit require a lot of extra equipment. opened. This method consists first of planning the In commercial use, the etched card is layout on a piece of paper, drawing out the probably favored most by the manufactur- design and employing the actual compo- ers. It utilizes a sheet of copper foil which nents to be used to help provide physical is laminated to a phenolic base during man- dimensions. After the design has been sat- ufacture. The circuit is printed on the cop- isfactorily settled on, it is transferred per side with to a special ink by one of a a piece of IA6" copper laminate by using a number of different methods. The printed center punch or scribe. A sharp model knife cards are then placed in a bath of ferric cuts the pattern onto the copper and the 74 POPULAR ELECTRONICS

.1.r PIS' 4.: ÍYfFr.lr tC, '.;11_ ^.ro.AmericanRadioHistory.Com if..+.. ir i? Why not make printed RIC circuits this easy way - it's inexpensive, compact, and interchangeable

t; Pf:uL F RUNGE

cut the copper Peel the unwanted copper of he laminate With a sharp model knife, ce enough so that the unwanted por- with a sharp knfi.. D= this slcvwly s, lust deep remcdning ccnductors. tion may be peeled off. Use a metal rule. to avoid tearing tk3

unwanted portions of the copper are simply peeled off. A few general observations may prove helpful before actually laying out the base. In printed circuitry, generally speaking, all components are mounted on one side of the base. This is not a hard and fast rule and may be varied to suit individual needs. The components may be mounted directly in small-size holes drilled into the copper strip, or an "island" may be formed which is slightly wider than the strip, and an eyelet inserted. Generally, relays are not mounted on printed bases; this permits a compact unit and follows the trend of separate mounting which is rapidly developing. Advanced R /C'ers find that it is far better not to mount the relay on a receiver base, since weight may be distributed more easily, and crash damage is considerably minimized. Lightweight soldering irons are a must for Rub steel wool over the copper conductor circuits. They should be about 25 side of the printed base to eliminate any printed rough edges and to prepare for soldering. to 371/2 watts, and should be used with a fine low -heat solder. A multiple core type, 75 August, 1955

AmericanRadioHistory.Com such as an Ersin, has a low melting point, making neater joints. Heavy irons and high temperature solder might cause blisters which would pull the copper laminate away from the phenolic base, and then the troubles would begin. Almost any circuit may be put on a printed circuit card. One of the easiest as a beginning project, however, would appear to be the "Lorenz 61" receiver, published in POPULAR ELECTRONICS in November, 1954. Following is a step -by -step explanation of the making of a printed circuit using the "Lorenz Mount the components on the base as re- 61" as an example. quired and then solder the lot after all parts are mounted and connections made. Mounting a Circuit Gather all the components called for in the circuit. Plan on making the copper lines wider than actually necessary -%2" to 1" should be ample. Finer lines and extreme miniaturization may be attempted later. The use of flea clip§ for subminiature tube leads is recommended, so that the tube may be removed. Eyelets may be used if the tube is to be soldered onto the base. Special miniature sockets for printed circuits are available for the miniature tube types, such as the 3A4, etc. With the parts, paper, pencil, and rule, juggle the components around, using the schematic to determine where to place each Be sure to use a small soldering iron and part. Many sheets of paper used in this a 'low temperature solder. Snip off all the step of the process will result in a much excess leads: brush off excess solder. neater unit. This is the most painstaking and time -consuming step. In two- and three - tube circuits, it may sometimes be necessary to place components so that they will bridge copper lines rather than have copper lines cross and short out. Jumper wire may be used for this purpose; however, careful spacing of components will make it unnec- essary in many cases. When the layout is satisfactory, double - check to make sure the "wires" correspond to the schematic. This is the time to correct wiring mistakes, since it will be too late to do so once the printed card is made. Cut the copper laminate to the size required for the base. (Small sheets of the Complete printed circuit version of the copper laminate by itself may be had from "Lorenz 61" R/C receiver made according Tele- Diagnosis Co., 155 West 72nd St., New to the instructions given in the text. York 23, N. Y., Ace Radio Control, P.O. Box 301, Higginsville, Mo., or Techniques Inc., 135 Belmont St., Englewood, N. J.) Transfer the paper pattern to the copper side of the laminate using a center punch, scribe, or any sharp- pointed tool. Connect the lines and draw a pencil pattern of the strips desired. With a sharp model knife, cut these lines just heavily enough to pene- BOTTOM VIEW TOP VIEW trate the copper. A bit of practice on some scraps will help determine the amount of If printed circuit layout has two lines which pressure required. must cross, use a component or jumper. (Continued on page 101) 76 POPULAR ELECTRONICS

AmericanRadioHistory.Com POPULAR ELECTRONICS Audio and Hi-Fi Section Tape Review 77 Disc and Bert Whyte 79 Birth of a Loudspeaker

82 Distortion in Hi -Fi Equipment orman H. Crowhurst 84 What Is an Audio Watt' Eugene F. Coriell, Major, USAF Square -Wave Converter 86 Howard J. Carter

Disc and Tape Review

By BERT WHYTE KNOW, this column has been de- AS YOU PROBABLY having voted in the main to a series of record reviews, of a basic classical record library. as its object the building to cull waded through a lot of records in an effort We have doing have the best recordings of many works. In so m we already compiled a sizable library, but of classical music is a vast subject. Even that the repertoire long way with the "basic library" as a goal, there is still a will continue to occupy a large to go. While this endeavor will of available space, the expansion of this column portion such as jazz, allow us to touch upon other areas of music, tape and other musical interests. "pops" ... prerecorded would Your letters and comments about this new format be greatly appreciated. Mendelssohn Symphonies must be reckoned in musical history Felix Mendelssohn violin as one of the most versatile of composers. Piano and sonatas, symphonies, oratorios, and many concerti, organ out- other forms of musical composition comprise his vast put. And music must be forever in his debt for resurrecting the works of Bach from dusty oblivion. Indeed, this is a fellow, and if you ever have the time and most interesting it opportunity to read the story of his life, you will find quite a fascinating one. August, 1955

AmericanRadioHistory.Com FT!«wItrllWnt,,11. w v wfr.ywglRl "9111111"1"71111"1"Till

As might be expected, a great musical cellent technician and knows his orchestra, talent like Mendelssohn is well served in but it is these very qualities which are also the matter of recordings of his works. He his downfall. He puts forth too much effort wrote five symphonies in all, but only the in having every note in the score "letter last three have gained a lasting place in perfect," and in so doing loses the essential today's repertoire. feeling of the music. Perhaps this is ac- 0 0 0 centuated by the sound, which is wide - The Third Symphony, subtitled the range, quite hi -fl and all that ... but suf- "Scotch" Symphony, is a cleverly construct- fers from very dry, cramped acoustics. ed and most melodious work. Seven ver- If you own any one of these three re- sions exist on LP, only three of which can cordings, you have a modern version of the be considered as modern hi -fl recordings. Mendelssohn Third Symphony, but for By far the best of these three is the those of you who have yet to acquire this Mitropoulos, N. Y. Philharmonic reading on work ... put your money on the Mitro- Columbia ML4864. I consider this recording poulos disc and you can't go wrong! as one of the finest things Mitropoulos has o o 0 ever done. The musicianship is of extremely high order. The sound too, is extraordi- The Fourth Symphony of Mendelssohn, nary. The N. Y. Philharmonic string tone the "Italian" Symphony, is his most popular is revealed as something which can stand work. This fact can be attested to by the comparison with the best. Especially nota- 16 versions of this work in the LP catalog! ble are the clean sonorities of the celli. Easily the most outstanding disc is the Dorati/Minneapolis Symphony recording on Brass, woodwinds, percussion . . . these, too, are heard with smooth, wide -range Mercury MG50010. This has the great ad- response, crisply accented where need be vantage of the fabulous "Olympian" tech- and with appropriately wide dynamic.range. nique single -Telefunken -mike sound. The Add to this picture the almost complete "Italian" Symphony is a rousing, brilliant absence of pre- or post -echo and other work, and particularly benefits from the distortions, and you have an outstanding sharply focused, cleanly articulate string recording. tone, the bright, incisive brass, and the low Next recording of the "Scotch" Sym- transient distortion apparent in the percus- phony in matter of choice is the Solti/ sion. Top this with ultrawide dynamics London Symphony version on London LL708. and good, live acoustics, and you have a This too, is a fine recording with sound most exhilarating sonic experience. Per- which, if anything, is even better than the formance -wise, Dorati knows and obviously Columbia. The main point of superiority enjoys the score, and his conducting per- is the superb transient response and acous- fectly reflects his attitude. His tempi are tic environment which is most persuasively brisk, his phrasing well modeled. He is not "live." However, the Solti performance, slovenly of detail; neither is he fussy to the while a solid, workmanlike job, point of distraction. His balance is always is not the judicious, equal in brilliance and inspiration of the as are his dynamics. In Dorati's Mitropoulos reading. hands, the "Italian" sings ... as it should . a bubbling, capricious, joyous The third recording for consideration is outpour- the Steinberg /Pittsburgh ing of beautiful music! Symphony effort Breathing hard on Capitol S -8192. Steinberg is a most ex- on Dorati's neck for second-place honors is the Leinsdorf/Roches- ter Philharmonic version on (of all things) the low- priced Columbia Entre label, RL- Contest 3102! Mr. Leinsdorf is another vastly un- for Hi -Fi Fans! derrated conductor, as is shown by his A FREE "week -end with high fidelity" masterful handling of the score. Save for plus a complete home music system is some tempo -tampering and occasional im- the first prize in a contest sponsored by balance ELECTRO- VOICE, with the orchestral choirs, his read- INC., of Buchanan, Mich. ing is properly This first nationwide contest for audiophiles warm and lyrical, and is and music lovers consists of completing, in really quite exemplary. In spite of the fact 50 words or less, the statement: "I would that this is on a low- priced label, the sound like to have an ELECTRO -VOICE matched is quite good. If the recording does not high fidelity system because .. have the brilliance and cleanness of the Nine other prizes include various E -V Mercury disc, it is nevertheless well re- loudspeakers. To enter the contest, partici- corded with good wide range, excellent dy- pants E -V must hear equipment at an E -V namics, and nice "live" acoustics. The ma- distributor, from whom they also obtain entry blanks. The contest closes at midnight, jor fault (and not too serious) is a rather September 30, 1955. characterless bass which inexplicably crops up at various places in the recording (prob- (Continued on page 112) 78 POPULAR ELECTRONICS

AmericanRadioHistory.Com Behind the scenes at Electro- Voice, Inc., where hi -fi speakers are made and +ested

1 Research and experimentation I in the laboratory (right) are the first steps in the birth of a loudspeaker. Permanent magnet field strength, suspension, elastic- ity, and frequency response are but a few of the physical factors that must be carefully analyzed before new speaker can be made.

From the laboratory, the 2 basic idea is sent to the model shop (left). Here, skilled craftsmen translate the engineer's dream into tangible form.

Alpha Wiggins (right) tests frequency 3 response of prototype in sound chamber from behind audio oscillator and recording setup. New model must prove itself before it can be put into production. When all problems are solved, model is "frozen" and sent to drafting for plans.

79 August, 1955 AmericanRadioHistory.Com A Performance of speaker In suitable enclosure is checked. In this test, the speaker system is placed in a "free-space" area out -of- doors. Sound output is picked up by microphone and fed into sound -level meters for measurement. Test at left is of speaker in folded horn cabinet.

After coil is wound and trimmed, it is positioned onto a plastic sleeve (above). This operation requires adherence to close tolerances. Voice coil will receive all electrical impulses that must be reproduced by Tests over, the speaker goes into production. Voice speaker cone as audible sound waves. 5 coils are wound on special machine. Next, voice -coil leads are trimmed to specified length. Edgewise -wound aluminum wire is used since it is light in weight and provides greatest number of turns within given area.

7 Voice coil and spider are combined into one assembly and cemented in place (above). Spider will hold speaker cone. It also acts as dust cover to protect magnet.

The cone (right) is made of pressed pa- UQ per. It is centered and cemented onto the coil-spider assembly. Its outer edge is glued to the outer rim of the metal frame. 80 POPULAR ELECTRONICS

AmericanRadioHistory.Com General view of assembly operations in 9 plant of Electro- Voice, Inc., Buchanan, Mich. Other operations include die -casting the speaker "basket' (frame) as well as varied and extensive machine -shop activities.

and strength of magnet determine, nWeight the quality of the loud- I V to a large degree, speaker. Alnico V, o powerful alloy is used widely. Above, the outer tube of a magnet structure is ground to 1 1000 -inch accuracy.

In the final stages of as- 11 sembly, vo.ce -coil leads are brought frcm spider to speaker cone. They are twisted into pigtails to prevent the damping of the cone as well as lead breakage.

Array of testing equip- 12 ment used in final inspection. Loudspeaker is operated under simulated "living room" conditions to determine performance quality. August. 1955 AmericanRadioHistory.Com MTORTI01 (PART 3) in }Ii -Fi equipment

two preceding portions of this dis- By NORMAN H. CROWHURST THEcussion have been concerned with frequency response (June issue, page 73) and phasing (July issue, page 70). In this con- sponding musical terminology. cluding section, a few The second words will be said harmonic is the first musical overtone. The with regard to harmonic distortion, noise, third and harmonic is the second overtone, and parasitic oscillation. so on. As mathematicians Many of the more advanced would write it, readers will the nth harmonic is the(n -1)th overtone. immediately recognize that these are the most prevalent sources of hi -fi and audio Intermodulation Distortion equipment distortion. Obnoxious and elu- The same type of causes sive to trace, these forms of in an amplifier distortion are that can produce harmonic distortion the most difficult to eradicate. Detection, single on a however, is -frequency sine wave can produce in- also an important problem, and termodulation distortion is the general theme of this article. when more than one frequency is applied at the input simul- There is a type of meter on the market, taneously. known as a distortion In practice, of course, all music meter, which is used and speech material consists with a pure sine -wave input to measure of a whole total the range of frequencies applied simultaneously. spurious components in the output. It So presence does so by filtering of this form of distortion means out the true frequency that a great many frequencies and measuring all that is left. This not present type of in the original sound will appear in the meter will not show up the varieties of dis- output. tortion previously discussed, but only the The basic test for intermodulation kinds that will be taken up now. distortion consists of putting in just two frequen- Harmonic Distortion The first kind is known as harmonic distortion, because the spurious tones added to the original sound are harmonics or regular multiples of the original tone applied. This kind of distortion can be measured by means of the meter already mentioned or a wave .4 analyzer can be used for more detailed analysis as follows. A pure tone is injected at the input of the amplifier and the output waveform is measured by means of the wave analyzer to find out what other tones are there besides the original tone put in at the input. Second, third, fourth, etc., harmonics of the original Fig. 1. The trailing edge of this sine wave tone are measured, and the distortion value shows a type of parasitic oscillation that of the output waveform is computed in is "triggered" as it passes through an ac- amplifier. cordance with certain rules. It might be a' This distortion would probably good idea at this point not be audible on a single sine wave, but to relate the nomen- will become clature of harmonic analysis to audible when a program of the corre- music or speech is fed through the amplifier. 82 POPULAR ELECTRONICS iillevii1NMt.JiYEliG71kY'I,re.Vdlitcl AmericanRadioHistory.ComL irJ n!",::: ,. "_ .. T ,., 1 7 "

effect may take a form sim- measuring the output for spurious The audible cies and ilar to harmonic distortion or perhaps ap- different from the two put in. If it is frequencies are pear more like intermodulation, but a low frequency and a high frequency from either of these the spurious frequen- really a little different put in simultaneously, of distortion. The easiest high frequencies differing particular forms cies will be other identify it is by means of the oscillo- the original one by a number equal to way to from scope. As soon as the waveform is presented the low frequency. will be observed quite 2000 cycles on the oscilloscope, it For example, if 60 cycles and is not audible. selected for the test, readily, although it are the original tones two kinds of parasitic oscilla- will produce spurious frequen- There are the amplifier tion, one of which is set off. at particular cies such as 1940 and 2060 cycles if it suffers in Fig. 1. The num- points on a waveform, as shown from intermodulation distortion. sine -wave input signal, sample spurious fre- Using only a single bers quoted are just not even have any audible effect, practice, a whole sequence of this may quencies. In because the high frequency burst does not frequencies could also be produced in addi- at all; and 1820 and move the loudspeaker diaphragm tion to these two, such as 1880, frequency of the sine wave etc. the fundamental 2120, 2180, works the loudspeaker in its normal fashion. If, on the other hand, two frequencies frequencies to the input However, if there are other fairly close together are applied (Continued on page 128) of an amplifier, and it suffers from inter - modulation distortion, a frequency equal to the difference or sum of the original two frequencies will appear. For example, if 3000 cycles and 3500 cycles are applied to the input simultaneously, a frequency of 500 cycles may appear in the output, although it was not applied at the input. Additionally, a frequency of 6500 cycles may appear, but to the ear the 500 -cycle tone is probably the one that could be most annoying in this particular example, because it might well inter- fere with other lower frequency components and produce notably undesirable effects. Parasitic Oscillation Another kind of distortion that does not come conveniently under any of the head- ings already discussed is caused by spurious at high audio fre- or parasitic oscillation Barker even radio frequencies. This Distortion meters, such as the quencies-or Model 400 shown above, is usually not audible in & Williamson kind of oscillation extensively to determine the noise will have a distorting effect upon are used ranges. itself but harmonic content in the audio the sound which is audible. and

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ap- Fig. 3. This is how a waveform will Fig. 2. An oscilloscope would show con- material is fed through in a form some- pear when program tinuous parasitic oscillation amplifier at the same time that parasitic music is coming through the thing like this. No oscillation is taking place. The audio would the amplifier. Usually such amplifiers are from time to time high fre- break up the oscillation surprisingly quiet because the sounds would suddenly appear effectively "blocks" the and original quency oscillation the output for very short periods of time. normally in the background. in hiss and hum 83 August, 1955

AmericanRadioHistory.Com By EUGENE F. CORIELL, Major, USAF

A question that puzzles many hi -fi enthusiasts is answered O ACCOMPLISH useful work, whether it be wattage it can absorb. This value moving a car along the highway or be should moving the cone at least equal to the amplifier rating, of a loudspeaker to pro- and in the case duce sound, power must be expended. of several speakers, the more power The combined power rating should equal expended, the more work done. amplifier rating. the Mechanical power is generally expressed horsepower in Within the amplifier, the and electrical power in watts most obvious or kilowatts. element important from an audio wattage The concept standpoint is the output transformer. This of electrical power is im- is the last component portant to the audio hobbyist because in the final stage of most al- the amplifier, and is the component every element of a tape recorder or loudspeaker that the hi -fi rig generates, transmits, "sees." The output transformer or absorbs is a device which matches power -electrical watts. The end output tubes to the result is the speaker voice -coil. If the driving of the loudspeaker, and since rated amplifier is the air opposes movement at 10 -watts output, the transformer of its cone or must be able to handle diaphragm, power must be expended this power. If it is overcome to too small, distortion or burn -out that opposition. In the case of may occur. the loudspeaker, Another element within an amplifier the driving power is fur- which is important, nished by the amplifier which wattage -wise, is the is rated as lowly resistor. There are many having an output of 10, 20, or more audio of these in watts. It follows the average amplifier, although not all of that the speaker must them handle appreciable also be rated as to the electrical power power. Resistors or are available in many different resistance These two instruments are typical of the commercially available ing audio watts. At the units for measur- right is the Heathkit Model AW -1, which principle to measure a voltage utilizes the v.t.v.m. across internal load resistors. On the General Radio Model 583A, a professional left is the ments laboratory unit. Both of these instru- have provisions for matching the impedance of the amplifier under test.

84 POPULAR ELECTRONICS AmericanRadioHistory.Com from the in ohms, and in various power power that the amplifier draws ratings is the real source ratings. In home amplifiers, the resistor house a.c. system, which may range from one -quarter of the power fed to the loudspeaker. power rating one watt delivered to several watts. The resistor rating Continuous power of watt will result in an uncomfort- is important at some positions in the am- to the speaker forced ably loud program in the average living plifier circuit since the current why use resistor by the applied voltage room. The question then arises: through the 20 or more watts? in of power by the re- amplifiers rated at 10, results absorption has a very low effi- sistor. This power is dissipated as heat, The cone -type speaker value ciency. This means that only a small frac- and a resistor of correct resistance fed to low a power rating may fail tion of the electrical or audio power but with too useful sound (horn - completely or cause noise in the amplifier the speaker creates type speakers are more efficient but are output. systems). It might be well here to distinguish be- less common in home the 115 - Another reason for building considerable tween the audio power input and fact input to the amplifier. For power output into amplifiers is the volt house a.c. many instantaneous peaks 10 watts of audio output, the house system that there are that much of sound in music which are far above the must furnish several times capacity in the amplifier 115- volt'a.c. input. average level; lack of power power to will result in distortion on On the other hand, the microphone or rec- the amplifier an extremely these peaks. Still another reason is the ord player furnishes only a room full minute amount of program power to the need for reserve power when audio input of guests creates a high background noise amplifier audio input. This tiny on from a few microwatts to level-or when the hi -fi fan insists power, ranging for better reproduc- milliwatts, in effect controls the 115 -volt turning up the volume tion of the extreme lows and highs. The need for reserve power becomes more apparent when it is realized that doubling the audio output from the amplifier will SECI achieve only a moderate increase in loudness. While most amplifiers will deliver LOAD rated output, the dis- RESISTOR more than their D.P.DT. tortion percentage will generally rise above value, which is AUDIO AMPLIFIER SCOPE the manufacturer's stated OSCILLATOR UNDER TEST the per cent of harmonic distortion at rated output. A really high -fidelity ampli- PHONO INPUT fier will deliver its rated output with 1% distortion or less. Fig. 1. This is the test arrangement for setup for meas- the power output of a hi -ii am- Figure 1 shows a simple measuring A sine -wave plifier. The vacuum-tube voltmeter must uring amplifier output power. be sensitive enough to read the extremely audio oscillator furnishes a steady signal small voltage input to the amplifier as sped- at a particular frequency, perhaps 1000 fled by the manufacturer, which may be cycles, to the amplifier input. Amplifier only a few millivolts. Output wattage is output is loaded by an appropriate resistor equal to the square of the voltage as meas- in place of the speaker (see speaker im- ured by the v.t.v.rn. divided by the value A vacuum -tube voltmeter this pedance rating). of the resistance of the load resistor; -and an oscilloscope if available -is in resistor is a substitution for the speaker. vol- for actual parallel with the resistor. Amplifier The oscilloscope is not required at which wattage measurements, but enables the ume control is set at the point sine -wave pattern to be checked for dis- the output is to be measured and the oscil- tortion. Power output is measured at var- lator control is adjusted to obtain the am- ious frequencies over the response range plifier input voltage recommended by the of the amplifier. See text for details. manufacturer. Output of the amplifier in (Continued on page 120) 85 August, 1955 a,.....: AmericanRadioHistory.Com SOIJARE- WAVE CONVERTER

By HOWARD J. CARTER

The converter is mounted in a small standard aluminum box. See Interior view at left.

Useful adaptation of a

little known circuit to

form clean square waves

from sine waves, valuable

in testing all types of hi-fi and audio amplifiers Control RI is mounted on end plate near tube socket. The three terminals include both - input- and - output - circuits since the ground terminal is common to each.

interesting presentation by Norman As the input voltage increases, there will be THECrowhurst on the use of square waves to a certain point at which regeneration within test hi -fi equipment (POPULAR ELECTRONICS, the tube will take place. This causes the July, 1955, p. 70) raised the following output voltage to jump suddenly to a high question among many readers possessing value. The high value is maintained until sine - -wave audio generators : "How can I on the downward slope of the sine -wave- get a square -wave signal source ?" This the critical "cutoff" point is once again article is the answer to that question. It passed and the output returns to the low describes the simple construction of a con- voltage setting. verter which takes a sine -wave input and This effect has no relationship to the makes it into a square wave. Technically length of time that the input voltage re- speaking, this is a Schmidt discriminator. mains at either the high or low value. In Unlike normal hi -fi amplification where other words, the circuit is essentially inde- the output is identical to the input, only pendent of the frequency of the sine -wave greatly multiplied, this circuit has only two input. The input may then be varied to suit output voltage levels. When the sine -wave individual circuit requirements with assur- input voltage falls below a certain critical ance that the output will always be a square value, the output voltage will be quite low. wave. 86 POPULAR ELECTRONICS AmericanRadioHistory.Com The output waveform will be a sharp - corner square wave up to input frequencies INPUT WAVEFORM of 10,000 cycles; above this frequency, the input sine -wave amplitude must be in- -Eh creased to maintain fast rising and falling edges. For audio amplifier testing, however, -E1 a 10,000 -cycle fundamental is quite ade- 1 quate. Plate supply voltage may be anywhere from 50 to 250 volts. The output will then be from 6 lo 30 volts, and the input peak -to- peak minimum will be from 3 to 12 volts. Although a 12AX7 tube is specified, the same OUTPUT WAVEFORM results may be obtained with a 12AT7. Lay- out of parts is not critical. Twist the heater How the converter operates when a sine wave wires together to reduce hum pickup. A knot is introduced through the input terminals. E(h) should be tied in the power wires inside the and E(i) represent critical operating levels. box for strain relief. Use spaghetti on the Normally, the output voltage would be a low capacitor leads to prevent shorting. Some level, but as the sine -wave input increases constructors will find that the circuit is there is a critical point, Elh), where regenera- cathode resistor R6 compact enough to be added easily to the tion through the common causes a sudden sharp increase in the output. chassis of their sine -wave audio generators. This new level is maintained until the sine To use the converter, connect the power wave drops to E(i) when the output is returned lead wires to the appropriate points on the sharply to the lower value. Ratio of the output amplifier under test. If low -level stages are square wave is adjusted by R1 to a 1:1 ratio. being tested, the output will have to be A pure sine wave need not be used at the input. attenuated with a compensated voltage divider as shown on the schematic. Set the trimmer Cx to the point where the oscilloscope shows 6+ the best square wave at the R7 junction of the potentiometer, 22K C2 Rx, with the amplifier tarder OUTPUT CI 0.14íd. 5 -45 test connected. -0- j 44ía INPUT Ol4fd 50K CX RI R* 500K 1/2 12AX7 DIVIDED the - VI, OUTPUT Wiring schematic of square (SEE TEXT/ wave converter. The potentiometer, RI, is used to set the level or ratio GROUND of the output. This adjustment should permit the user to obtain a square wave that appears very 6.3 VA C. similar to (a) of Fig. 3, page 71, July issue. It must be made since the output waveform depends on the input sine wave and plate voltage e+ is to the converter. which applied GND R1- 500,000 ohm potentiometer 12AX7 R2- 470,000 ohm, 1/2 w. res. Milk TUBE R3- 68,000 ohm, 1/2 w. res. VI R2 A R4- 240,000 ohm. I/2 w. res. mio«, 1/2 w. res. Di1é'p" R5- 92,000 ohm, ., 6.3V. R6- 47,000 ohm, 12 w. res. , R7- 22,000 ohm, lit w. res. i,-- !`°.,. -, CI, C2 -.1 µ1d., 200 v. paper capacitor Cx -4 -80 µµtd., mica trimmer or gad- ;,P `- . . der capacitor ` Rx- 50,000 ohm potentiometer, linear fllllt taper 'R1 C1 R4 A C2 V1 -12AX7 tube (or see text) '' Also required: 1- Aluminum case, 21/4" x 21/4" x 4" 1 -9 -pin miniature tube socket 3- Superior 5 -way binding post 1- Terminal strip Total cost of parts, approx. $5.00 SINE WAVE 1t COMMON ^It SQUARE WAVE INPUT GROUND OUTPUT

87 August, 1955

AmericanRadioHistory.Com AFTER 'CLASS POWER TRANSFORMERS

HE HUM of a transformer is a song of rent (Is) flows through the load. In mod- leashed power held in check by the skill ern power transformers, practically all of of design and construction engineers. In the lines of force produced by the primary some transformers it signals lethal voltages current cut through the secondary wind- lying in wait for the first incautious move; ing; this is a matter of proper design and in others it tells of gentle voltages applied materials. When it occurs, the windings to delicate tube filaments. In any case, we are said to be "closely coupled," a con- can learn to handle this versatile com- dition that results in most efficient opera- ponent by becoming familiar with the basic tion. rules that govern its operation. It should be pointed out that transform- A power transformer -the simplest kind- ers operate only on alternating current, consists of two separate coils of insulated since the process of inducing a voltage in wire wound around a common core of the secondary winding depends on a change in the magnetic lines of force. Don't let anyone talk you into trying to locate a d.c. transformer! Most of the electrical power in this country has a frequency of 60 cycles per second, although some 25 -cycle power is still in use in various localities. ji The secondary voltage, Es, may be found by applying this simple formula: Secondary turns Es = Ep X Primary turns Suppose we have a transformer whose primary has 500 turns closely coupled to a 2000 -turn secondary. What secondary voltage may we anticipate if the input to the primary is 120 volts? Substituting in the formula above:

Es = 120 X 250Q = 480 volts Thus, this is a step -up transformer which (B) boosts the input voltage to four times its 63V. original value. The fraction 4/1 is called r- HTR -` TRANSFORMERS the S:P turns ratio. Evidently, from the example given above, is LINE the turns ratio INPUT OUTPUT equal to the fraction VOLTAGE "Secondary turns/ 12o v. Primary turns" and may be used in place of it in the equation, so that: Es = Ep X turns ratio (C) Take another example: a filament trans- silicon steel or some similar material that former (a step-down type) designed to op- concentrates magnetic lines of force. As erate on 120 -volts primary input has a a fluctuating voltage (Ep in Fig. A) is im- turns ratio of 1:20 (another way of writ- pressed across the primary (pri.) coil, the ing 1/20). What secondary voltage will it pulsating magnetic field that results from produce? Using the second formula: the flow of primary current (Ip) cuts through the secondary turns (sec.) inducing Es = 120 X 20 = 6 volts a new voltage (Es) in this winding. If a load that can consume electrical power is By exercising care in the design of the connected as shown, then a secondary cur - windings and the choice of the core, both 88 POPULAR ELECTRONICS

AmericanRadioHistory.Com I!I; MP,ay,*(1gr!g.`iWt r .:::aeri, r :glN;zyl.

transformers described in the foregoing having an S:P turns -ratio of 1:10 yields the paragraphs' may be combined to form a right voltage when used on a house line. multiple winding type as shown What must be the line voltage? standard How much current flows in the primary of the in Fig. B by winding both secondaries on 3. transformer described below? Is this a step - the same frame as the primary. up or step -down transformer? Contrary to the convictions of many be- Primary voltage = 2500 volts ginners, transformers don't give you some- Secondary voltage = 125 volts thing for nothing. Although it is true that Secondary current = 100 amperes a transformer can step up voltake, in the 4. Very often, two filament transformers of iden- process of so doing it balances the score tical rating are used "back-to-back" as shown by taking more current from the lines than in Fig. C. This brings about a favorable con- it provides to the load. No transformer can dition called "isolation from the line." What supply more power to the load from final secondary voltage might be expected? ever 5. A certain step -up power transformer having a the secondary winding than is put into its turns ratio of 10:1 blows a fuse in its primary primary winding. Under ideal conditions circuit when the load on the secondary is of 100% efficiency, the secondary power made excessive. How can this happen? may equal the primary power, but it can never exceed it. Ignoring power factor (to ELECTROSTATIC SPEAKERS be discussed in a future issue): beginning Ip power Electrostatic speakers are Ep X = primary modern, medium - secondary power to find their way into Es X Is = priced high -fidelity equipment. It seems a Thus: good idea, then, to review the principles of EpXIp =EsXIs this unique kind of loudspeaker to see how This last equation can be rewritten as: it fits into the hi -fi picture of today. Ip = Is X Es /Ep An electrostatic speaker is nothing more and may be used to find the amount of than an elegant capacitor having one flex- primary current that will be necessary to ible and one rigid plate. The principle of provide a given secondary current to a its operation is quite simple. Audio volt- load when a given transformer is used. ages applied to the plates of the capacitor For instance, consider our first example of set up a varying electric field between a transformer having a turns ratio of 4/1. them. Since this field contains more or less Assume that this device is to operate a energy depending upon the amplitude of radio set which acts as a 100 -milliampere the potential differences, the flexible plate load. Now much primary current must is caused to move in step with these vary- flow to supply this current at 480 volts ing potentials. The air in contact with the in the secondary? moving electrode is then set in motion at Ip = 100 X 480/120 an audio rate and sound results. Ip= 100X4 =400 ma. A typical circuit in which an electro- speaker is used in combination with Therefore, as the transformer quadru- static

ples the input voltage by its step -up action CI C2 to provide an output voltage of 480 volts, 00 0 E the current taken from the lines by its SPEAKER times than LI primary winding is four greater POWER 50 hr that provided for the load's use. This OUTPUT "balancing" action is completely automatic TUBE by a law of physics and is dictated natural 220K called "the conservation of energy." If we AUDIO could invent a transformer that would pro- INPUT vide more secondary power than that con- t 2':Uv primary, perpetual motion ELECTROSTAT C sumed by its SPEAKER would be the easy step! The following quiz is intended as a self check. All of the questions can be an- a PM cone speaker to form a "woofer - swered correctly if the foregoing text has tweeter" arrangement is given in the fig- been mastered. Answers are on page 127. ure. Capacitors, Cl and 02, and inductance, QUIZ LI, form a cross -over network which feeds 1. Radio sets made in this country and shipped the high frequency audio to the electro- to Great Britain are usually accompanied by static speaker while keeping the low fre- transformers to permit the use of the 110 -volt quency components directed toward the radios on 220-volt lines employed in the latter low- frequency cone speaker transformer. country. What must be the S:P turns ratio of Early models of electrostatic speakers these transformers? they could not 2. A 12SQ7 tube heater requires 12.6 volts for had two big disadvantages: proper operation. A step -down transformer (Continued on page 98) August, 1955 89

AmericanRadioHistory.Com This simple, home- constructed chassis was made of aluminum and follows the method described by the author. Thin -Skin Chassis Cuts Costs

AMONG the many problems facing the Use of these materials has turned out average experimenter is the cost of the particularly well for the author. Once a chassis which must be used as a foundation circuit is operating satisfactorily, the unit for almost every piece of equipment which may be permanently wired on the same is constructed. chassis which was used as a breadboard, If one is to make his own chassis, a ma- or if need be, a new top plate may be cut terial that may be easily worked is a prac- to allow a better parts arrangement. tical necessity, particularly if shop facilities When the top plate is drilled and punched are limited. One such material is 1/2" (including holes for mounting to the base), wire mesh, which is both cheap and easily all major components may be mounted and worked. However, this material leaves wiring completed, with the exception of something to be desired as far as eye appeal the controls and switches which are to be is concerned. In addition, the shielding mounted on the front of the chassis. This offered by the 1/2" mesh is inadequate produces an almost integral unit on the with some circuits, as several units con- chassis plate, which materially simplifies structed by the author were affected by construction and any subsequent changes body capacity. which may be necessary. It was, therefore, decided that the only In assembling a chassis, the details shown alternative material was aluminum. The in the photographs will serve as a guide. first attempt at a home-constructed chassis However, it should be noted that there is resulted in a very serviceable but decidedly a 1/2" flap provided for joining the two "unpretty" aluminum box. ends of the base. All bends should be For the next project, a quantity of 18- accurately scribed and care exercised in gauge 24ST aluminum was purchased from making all cuts so that the finished job a surplus outlet for use as top and/or bot- will be structurally strong as well as nice - tom plates. For the sides some 24 -gauge looking. A coat of wrinkle paint will further aluminum was secured from a local hard- dress it up and give that elusive profes- ware store. The 24 -gauge material is very sional appearance. easily worked and can be bent with only While the completed chassis is not as a light hand pressure, as may be seen in strong as a commercially built job, it is the accompanying illustrations. perfectly adequate for most applications. 90 POPULAR ELECTRONICS

AmericanRadioHistory.Com Only light pressure is required to bend the aluminum. The sheet, clamped between two boards, is supported on a flat surface for bending.

In order to form the corners of the , chassis, a piece of wood whose width equals the chassis' depth is used.

By RICHARD C. SAUNDERS

However, the addition of a bottom plate will add considerable strength to the unit, if it is found necessary. This method of construction has the advantage of being relatively cheap, and in addition, no special tools are required. Even if tinsnips and 'C' clamps need to be purchased, the savings on the first few chassis will more than pay the cost of the tools. 30

Both aluminum chassis illustrate6 were built at a total expense of 70 cents.

August, 1955 91

AmericanRadioHistory.Com Heathkits arc fun to build with the simplified - easy to-follow Construction Manual furnished w with every kit. Only basic tools are required, roatlnR ehar such as soldering iron, long -nosed pliers, diagonal cutting pliers, and screwdriver. All sheet metal bépaoÌ RraY work has already been done for you. No cutting, drilling, or painting required. All parts furnished including tubes. Knowledge of electronics, circuits, etc.. not required to successfully build Heathkits.

7/ PRINTED CIRCUIT VACUUM TUBE eA° °c h alo,w VOLTMETER °°°`P°° K IT kß"As. The VT \ is tile standard baste cItage measuring instrument for radio and TV servicemen, engineers, laboratory technicians, experimenters, and hobbyists. Because of its extremely high input resistance (11 megohms) the loading effect on the circuit being measured, is virtually negligible. The entire instrument is easy to build from a kit, with complete a detailed step -by-step Construc- prinLTdlicstert. tion Manual. Featured in this instrument is an easy -to-wire fool- cw proof printed circuit hoard which cuts assembly time in half e eastec_exact duVltcattone- CIRCUIT AND RANGES: Full wave AC input rectifier permits ot Labéni °núdel. 7 peak -to -peak voltage ranges with upper limits of 4000 volts peak - vcloDm to-peak. Just the ticket for you TV servicemen. Seven voltage ranges, 1.5, 5, 15, 50, 150, 500 and 1.500 volts DC and AC RMS. Peak -to-peak ranges 4, 14. 40, 140, 400, 1400, and 4000 volts. Ohm- Model V -7 meter ranges Xl, X10, X100, X1000, XIOK, X100K, XI meg. Additional features area db scale, center scale zero position, and a polarity reversal switch. IMPORTANT DESIGN FEATURES: Transformer operated -1C;, precision resistors -fiAL5 and IJAl'7 tubes -selenium power rectifier -individual AC and DC calibrations smoother improved zero adjust control action -new panel styling and color -new placement of pilot light -new positive contacs battery mounting -new knobs -test leads included. Easily the best buy in kit instruments. eaten ------; HANDITESTER KIT The lieathkit Model M -1 Handi- MULTIMETER tester readily fulfills all requirements for a compact, portable volt - KIT ohm-milliammeter. Its small size permits the Instrument to be tucked into your coat pocket, tool box or Here is an instrument packed glove compartment of your car. Al- with every desirable service fea- ways the " handitester" for those simple repair jobs. Packed with every ture and all of the measurement desirable feature required in an in- ranges you need or want. High strument of this type. AC or DC sensitivity 20,000 ohms per volt voltage ranges, full scale 10, 30, DC, 5000 ohms per volt AC. Has 300, 1000 and 5000 volts. Ohm- the advantage of complete port- meter ranges 0 -3000 ohms and ability through freedom from AC DC milliam- 0- 300,000 ohms. line -provides service ranges of meter ranges 0 -10 milliamperes and 0 -100 milliamperes. Uses direct current measurements MODEL M1 400 microampere meter -1y from 1.50 microamperes up to 1S MODEL MM -1 precision resistors- hearing aid amperes -can be safely operated Shpg. Wt. type ohms adjust control -high in RF fields without impairing 42950 6bs.l 145o quality Bradley rectifier. Test accuracy of measurement. wt. leads are included. Shpg, 3 fbf. Full scale AC and DC voltage ranges of 1.5, 5, 50, 150, 500, 1500, and 5000 volts. Direct current ranges are 150 microamperes, 15, 150, and 500 milliamperes and 15 amperes. Resistances are measured from .2 ohms to 20 megohms in three ranges and db HEATH COMPANY range from -10 to +65 db. Ohmmeter batteries and necessary test leads are furnished with the kit. A SUBSIDIARY OF DAYSTRI)M, INC. BENTON HARBOR 10, MICHIGAN

92 POPULAR ELECTRONICS

AmericanRadioHistory.Com USE: This brand new Utility Scope was designed especially for servicemen and radio amateurs, and is adaptable for use in all general Scope applica- etc. Use it to tackle alignment h áñá'rk mentááh hamrra or adjustment (problems. Equally )valuable in breadboard work. must aervlefng¡ó outsideInarru for ham shack or for outside servicing.g DESCRIPTION: Front panel controls of the Model 01.-1 are "bench tested" for ease of opera - Comp pelgbt tion and convenience. Sharp focusing 3e CRT. 1;go1e Printed circuit for ease of assembly and constant v Veld.-Niceld performance. Assembly time cut in half! High feet r quality electronic components used. Sensitive hor. oP teflon. and vert. amplifiers with broad freq. response; cathode follower for isolation. Push -pull hor. and vert. ai"w 1 output to deflection plates. Int 60 cycle, or ext. °añ jg gá sync. Sweep freq. range 10- 100,1100 cycles. Direct lettery with rY,. connection to deflection ,plates., Provision for Z lig Model 55 kn L [Ire axis input. Uses 3GP1 CRT, 4 -12AU7 hor. and te°rd androni vert. amplifiers , I -12AX7 sweep gen., 1 -6X4 OL- 1 mina) áad ng nos New fared s Model 0L i Isla real standout value ;attonly Shpg. Wt. circuit for $29.50, and is another example of the famous rcmt pertcarats nt p ágce °t+°- H ea thk'ti combination;b' C ion; qua liti y plus1 economy. 15 lbs. com. s2 q Ponenó mountinggetl Measures only cut Ins had ,time 1940 6d3weighs only 11 pounds.

Neu. and ' k n:,,i Orna,i frequency ")j f atsionai °-1 coverage - fun- T7- eae%f/ redo, d ann damentals from ^n 160 KC to 110 Cathode follower 'al MC in 5 bands output for good -up to 220 MC Isolation - fixed on calibrated step and continu- harmonics. ouslyly SIGNAL GENERATOR KIT attenuation. USE: This instrument is "serviceman engineered" to fill the requirement for a reliable basic service instrument at moderate cost. Frequency coverage extends in five bands from 160 Kc. to 110 Mc on fundamentals, and dial is calibrated to 220 Mc for harmonics. Pre -wound and pre -aligned coils make calibration unnec- essary for service applications.

DESCRIPTION: The Heathkit Model SG -8 Signal Generator provides a stable modulated or unmodulated RF output of at least 100,000 microvolts which can be controlled by both a continuously variable and a fixed step attenuator. In- ternal modulation is at 400 cycles, or can be externally modulated. AF output of 2 -3 volts is also available for audio testing. Uses dual purpose 12A117 as Colpitts RF oscillator and cathodefoilower for stable, isolated, low impedance output, and ó type 6C4 tube for 400 cycle oscillator. Operation of the SG -8 is well within the m I - for service work. Modern styling features an,ï pure=V r.r., frequency limits normally required or audio output. high definition white letters on charcoal gray panel with re- designed control knobs, C Sling. Wt. Modern nrofcesmnal appearance and Heathkit engineering know -how combine 50 MODEL SG-11 $ 3 lbs. t o !hare his instrument in the "best buy" category. Only $19.50 complete. 4eit(%síANTENNA qeetetZa IMPEDANCE I GRID DIP METER METER KIT KIT The Model AM -1 Antenna Impedance Meter makes an ideal companion unit for Amateurs and sery - the GD -1B Dip t Grid Meter or a valuable itcemen bave proven instrument in its own right. Perfect for e aeltuee thi s grid checking antenna and receiver impedance dhp r mofa s for and match optimum system operation. oer. Indispnsme MODEL Use on transmission lines, half wave, folded dipole, or beam antennas. Will double as tircsloatuintg aarasit-, AM -1 monitor or relative P Id strength meter. MODEL aannd aligning firgs Covers freq. range of 0-150 Mc and im- B f d traps ino TV or GD -1 Shpg. WI. pedance range of Uses 100 $1450 0-600 ohms. Radio and for interfer- 2 lbs. microampere meter and special calibrated ence proD-ems. The potentiometer. A real buy at only $14.50 ('1J:o jhpq. Wf. complete. Model GD 1B touera T 4 s. from 2Mcto250Mc D with 5 pre-wound coils. Featuring a sensitive 500 microampere meter an d phonejacl',the GD-IB uses a 6AF4 or 6T4 tube. An essential tool for the ham HEATH COMPANY M or serviceman. ACCESSORIES: Low freq. coverage to 355 KC with A SUBSIDIARY- O° OAYSTROM, INC. two extra coils and calibration curve. Set No. 341A BENTONI HARBOR 10, MICHIGAN for GD -IB and set No. 341 for GD-IA. Shipping weight 1 lb. Only 53.00. I August, 1955 93

AmericanRadioHistory.Com Smooth acting illuminated and precalibrated dial. MODEL VF -1 6AU6 electron coupled Clapp oscillator and 0At voilage regulator. I Band coverage. 160 through l0 meters -10 Voll RF output. Copper plated chassis -aluminum cabinet -easy to build- direct $1950 haying. Smooth acting Ship. Wt. 7 lbs. Open illuminated layout - dial drive. Clew easy to build appearance - simplified rugged Here is the new Heathkit VFO you wiring. construction- have been waiting for. The perfect - companion to the Heathkit Model alibratingcaccessible AT -I Transmitter. It has sufficient output to adjustments. drive any multi -stage transmitter of modern design. A terrific combination of outstanding _Émn ,od features at a low kit price. Good mechanical Ceramic coil and electrical design insures operating stability. Coils are wound on heavy duty difeential ceramic forms, using Litz or double cellulose wire coated with polystyrene condenser. cement. Variable capacitor is of differential type construction, especially designed for maximum bandspread and features ceramic insulation and double bearings. a This kit is furnished with a carefully precalibratcd dial which provides well over two feet of calibrated dial scale. Smooth acting vernier reduction drive insures easy tuning and zero beating. Power requirements 6.3 volts AC at .45 amperes and 250 volts DC at 15 mills. Just plug it into the power receptacle provided on the rear of the AT -I Transmitter Kit. The VFO coaxial output cable terminates in plastic plug to lit standard W crystal holder. Construction is simple and wiring is easy.

e.2 et AMATEUR TRANSMITTER KIT

SPECIFICATIONS: Range 80, 40, 20, 15 11, 10 meters. 6AG7 Oscillator- multiplier. Cstlry 61.6 Amplifier- doubler VEO exatcioru.n. 5U40 Rectifier. 105.125 Volt A.C. 50.60 cycles 100 watts, Steen 81/2 inch high x 131/5 inch wide x 7 inch deep.

Prewound coils - metered . Ship. Wt. operation. 16 lbs. Rugged, clean construction. Here is a major Heathkit addition to the Ham radio field, the AT -1 Transmitter Kit, incorporaring many desirable design 52 xi i features at the lowest possible dollar -per -watts price. Panel Single knob output. mounted crystal socket, stand -by switch, key click filter, hand A. C. line filtering, good shielding, etc. VFO or crystal excita- switching. tion-up to 35 watts input. Built -in power supply provides 425 volts at 100 MA. Amazingly low kit price includes all trend' components, tubes, cabinet, punched chassis, and Built-in power detailed construction manual. Supply.

eeadtleit COMMUNICATIONS RECEIVER KIT Noise limiter- standby switch. SPECIFICATIONS: Range 535 Kc to 35 tete 12B86 Mixer -oscillator 12BA6 I F. Amplifier 12AV6 Detector - AVC -awl in 12BA6 ....B. F. O. oscillator 12A6 Beam power output. 5Y3GT Rectifier 105 125 volts A. C 50.60 Cycles, 45 watts.

A new Heathkit AR -2 communi rations receiver. The ideal corn panion piece for the AT -1 Trans MODEL AR -2 Four band Six tube mttter. Electrical bandspread scale for tuning operation 535 to I ransfertner and logging convenience. High gain minia- $2550 to 3 i 51e. operation. ture tubes and IF transformers for high srnsitivity and good signal to noise ratio. Construct your own Communications Ship. Wt. 12 Ibs. Receiver at a very substantial saving. CABINET: Supplied with all tubes, punched and Proxylin impreg- COMPANY formed sheet metal parts, speaker. nated fabric cov- HEATH circuit components, and detailed step - ered plywood cab- A SUBSIDIARY OF DAYSTROM, INC. by -step construction manual. inet. Shipg. weight 5 Ihs. Number Ol- BENTON HARBOR 10 , MICHIGAN io, $4.50.

94 POPULAR ELECTRONICS

AmericanRadioHistory.Com NEW sea¢Gt BROADCAST ST RECEIVER KIT Here is the ideal radio kit for the student, beginner, or hobbyist. If you have ever had the urge to build your Here is an outstanding am- own radio receiver, this kit plifier value. This economi- deserves your attention. cally priced amplifier is Circuit is transformer oper- capable of performance ated, eliminating shock haz- usually associated only with ard usually associated with far more expensive units. "economy" circuits. Can be nicely used as the New high gain miniature MODEL heart of an inexpensive high tubes and IF transformera - BR -2 quality home music system. powerful ferrite core built- $175O Features inputs for tuner Shpg. Wt. in rod type antenna- chassis IOlbs. MODEL A -7B and phono (Model A -7C ac- mounted5 .r: %'PMspeaker- less Cab/nI commodates a microphone optional operation either as receiver or by an additional pre- tuner and phono input. using Covers broadcast band 550 S155? Shpg. Wt. -1600 $c. lises 12BE6, 12BA6, 10 lbs. amplifier stage). Separate 12AV6, 12A6, and 5Y3 tubes. bass and treble boost and CABINET: Proxylin impregnated cut tone controls for just the degree of tonal balance you fabric covered plywood cabinet available. Includes aluminum want. The entire kit can be built in a few pleasant hours for panel, flocked reinforced speaker years of enjoyment. grill and protective rubber feet. tit -9, Technical features, frequency response ± 1! 2 db 20- 20,000 Shpg. Wt. 5 lbs. $4.50 cycles. Full ti watts output. Push -pull beam power output stage. Output transformer impedances I, 8, and 15 ohms. Tube lineup, 12J5GT, 12SL7, 2 -12A6, 5Y3GT, F and 128.17 (A -7C only). Al is All parts including tubes are supplied along with a T RHere prefabricated and painted chassis. Detailed step -by -step construction m shroud the to operate aim. Construction Manual eliminates necessity for special- th outh "phono" either section of e ize.) knowledge. MOD former amplifier. ACtrans- EL FM rule o -2 type 8 tube trans. MODEL A -7C incorporates a preamplifier stage with coverage-threetuns dial -88 circuit oing -108 megacycle special compensated network to provide necessary gain $ tuned for operation with variable reluctance cartridge or mi- Shpg_ front IFetacle I,yS O at the of bull nedd regdhouc. $17.50 cal o 8 lbs. of true time eñ °Wp advanr FMM receptiono y all of the and advan ta¢ea HEATH COMPANY BENTON HARBOR, MICH.

ORDER MAIL YOUR O R D E R B L A N K TO THE TODAY Y SHIP VIA CMPAN Parcel Post HEATH C A SUBS,DnRV HARBOR IO' Express BENTON MICHIGAN Freight Best Way

(PLEASE PRINT) QUANTITY ITEM MODEL NO. PRICE

Enclosed find ( ) check ( ) money order for n On Express orders do not include transportation charges - Please ship C.O.D. ( ) postage enclosed for pounds. they will be collected oy the express agency at tune of delivery. ON PARCEL POST ORDERS ORDERS FROM CANADA and APO's insure postage for weight shown. must include full .emittance.

August, 1955 95

AmericanRadioHistory.Com pr1,tlp.s1A'!e-Y.¡.wii`i.R'grt°RIVP"F _ . -¡1TaRM'4f.1R,:',.f7"IR9,911197117MIrI!,+t51!7'."111 ï. .,,: .. .',

There is no convenient, cheap method of converting 25 -cycle power to 60 cycles. In some cases, it may be possible to obtain a 25-cycle WHAT'S THE transformer having characteristics similar to the 60 -cycle version, particularly in Canada where 25 -cycle power is more prevalent than in this country. Check with your local parts jobber. AANSWER? Meter for Geiger Counter I have just completed building the Geiger coun- \ \\\già \`". \\' \\ 3\ \\ ter described in the January issue. As I have a multimeter, would you print a circuit for using the Eliminating Radio Commercials meter instead of headphones? RODNEY PETREE The other day I saw a gadget that cut out the Calif. 4 commercials on FM. Can you tell me how this Calistoga, operates, or better, publish a drawing in one of We have had a number of requests for infor- your future issues. mation on adding a meter and neon flasher to ADAM F. SCHIMARISKI this Geiger counter. However, the unit was de- Evergreen Park, Ill. signed to be as simple and cheap as possible, Automatic commercial eliminators for AM or and the additions requested would call for a FM usually operate on the principle that voice major redesign, both electrically and mechani- frequencies have a different energy content cally. We suggest that anyone desiring a Gei- than music. Thus, circuits can be arranged to ger counter with a meter and neon flasher shut off the program when anyone is speaking, study the de luxe unit described in the July and turn it back on again when music is being issue. We also plan to publish other designs received. Such a system has several disad- from time to time, to give our readers a variety vantages; it will not shut off singing commer- of instruments from which to choose. cials, and it will shut off desirable programs Wireless Record Player etc. To such as news reports, commentaries, In the March issue of POPULAR ELECTRONICS, the best of our knowledge, there is no true you have a diagram for a wireless record player. "commercial eliminator" other manually than a I was looking it over and it seemed to me that operated switch. there would have to be an easier and cheaper Modifying Radio for Short Waves way to make one. I started to work on it and I have an old Philco Model 20 radio that's in came up with the one shown below. very good condition, and I would like to know if JERRY ZALUDEK I could modify it so that I can pick up short wave. Toronto, Canada From the way I look at it, I think I can, but some Thanks very much for the suggested circuit. It friends with more experience than I say I would is being reproduced here with the thought that have quite a job on my hands. others may wish to try it out. Actually, there STEPHEN DI CLEMENTE Philadelphia. Pa. We do not recommend that you attempt to alter your present receiver so that it will receive the short-wave bands. The best answer to your problem is to use a converter that will convert the short-wave signals to a frequency which can be received on your present receiver. We hope to publish details on such a converter in the near future. 25 -Cycle Operation What I would like to know is whether the proj-

ects that appear in POPULAR ELECTRONICS op- 55W. erate on 50/60 cycles only. I was wondering if you have or could design an instrument that is a wide variety of designs for a wireless rec- would change the frequency from 25 to 60 cycles. ord player, and it is difficult to say which is If not, is there any such instrument available on best without building and testing each one. the market? The basic principles are the same, however: GEO. JEACOCK, JR. an r.f. oscillator of suitable frequency and Toronto, Ontario power output is amplitude -modulated by the Transformers designed for 50/60 cycle opera- desired audio signal -usually the output of a tion will overheat and probably burn up if record player. This modulated r.f. is then used on a 25-cycle power line of the same volt- picked up by a radio receiver and reproduced age. Equipment of the a.c: d.c. type does not in the same manner as the signal from a contain a power transformer and so may be broadcasting station. operated at 25 cycles. However, the lower fre- One major disadvantage to the circuit shown quency requires more filtering capability to re- above is that one side of the power line is con- move the ripple from the rectified output, so it nected directly to one side of the pickup- may be necessary to add inductance or capac- which can lead to a severe shock hazard. ity or both to the power supply filter. 96 POPULAR ELECTRONICS

AmericanRadioHistory.Com National Schools brings you a new dimension in training for TELEVISION - RADIO - ELECTRONICS YOU CAN LEARN BY HOME STUDY, IF- Your Course Includes Valuable Units -you are ambitious to increase your earning power. We send you important equipment, including a com you want to broaden merciai, professional Multitester ... plus parts to - your knowledge and skill. build -you choose Receivers, Oscillators, Signal Generator, Con- the school with the most complete tinuity Checker, other units, and Short Wave and training, service and experience. Standard Broadcast Superhet Receiver. Mail Coupon for 50 Years of Successful Training Complete Information National These 2 free books explain our new dimensions in Schools has been training men for success Home Training. Get illustrated since 1905. Our graduates are located around the globe, fact -book and sample lesson. No in good -paying jobs in servicing, installation obligation, mail coupon now! and manufacturing...in public and private industry, or in their own businesses. NATIONAL SCHOOLS TECHNICAL What This New Dimension in Home Study Means TRADE TRAINING SINCE 1905 to You Los Angeles37,Calif. Chkage, 323 W.Polk St. As a National Schools student, with Shop Method In Canada: 811 W. Hastings SI.,Vancouver, S.C. Home Training, you master all phases of the indus- MAIL NOW TO OFFICE NEAREST YOU! try -TV, Radio, Electronics- theory and practice. You learn HOW and. WHY, in one complete course at (mail in envelope or poste on pasta) card) one low tuition. Age NATIONAL SCHOOLS, Dept. R2G-85 and education are no barriers. 4000 Because S. FIGUEROA STRPE7 323 W. POCK. STREET our world headquarters are in Los Angeles LOS ANGELES 37, CALIF., OR CHICAGO 7, ILL. "Capital -a City of Electronics"- we are in close Rush FREE Boox, "Your Future in Radio -TV- Electronics." touch with industry. Our lessons and manuals keep and FREE TESSON. No obligation, no salesman will call. you up -to- the -minute on latest developments. We show NAb19 you how to make spare time earnings as you B31RTiDAY- 10 learn, s.nd give you free placement assistance upon graduation. Bath our Resident and Home ADDRESa courses Study are approved for G. I. Training. If you CITY - ZOS1E STA1 of draft are age, your course helps you achieve special- Check if interested ONI,I' in Resident Training at Los Angela. ized ratings and pay grades. LVETERANS, Give dote of discharge

August, 1955 97

AmericanRadioHistory.Com , ` 11471"4"1S" I ;7ylcISOMI7.nsyl[,

After Class account the power factor of the circuit, and computes the power consumption in (Continued from page 89) the form of a meter reading which serves reproduce the low audio frequencies well as a continuous indication of the circuit and they often suffered voltage breakdowns wattage regardless of the changes that may because of the poor quality of the dielec- be taking place. Its accuracy very ob- tric materials available at that time. The viously depends upon the precision of its first problem is avoided by confining opera- design and construction and upon the care tion of the electrostatic speaker to the ap- taken by the operator in reading it. A slide proximate audio range of 6500 to 15,000 rule is another perfectly respectable infor- cycles per second. A low frequency speaker mation machine of the analog type : the is then required, of course, to supplement user translates numbers into movements the capacitor speaker, that is, to provide of the "slip- stick" and transformations reproduction over the range of 20 or 30 from one scale to another, while the slide A cycles to 7000 cycles or so. The second rule, proceeding according to the rules problem no longer exists because of the which have been built into it, provides a product, quotient, square, or cube root with high or low accuracy depending upon the quality of the instrument and the caliber of the operator. FRONT BACK A digital machine, on the other hand, works only with numbers. The machine processes the numbers in accordance with the rules of arithmetic and formal logic, POLYETHYLENE SHEET and expresses the answer in numerical form. A digital computer could calculate GOLD FILM the power consumption in an electrical cir- PERFORATED COPPER BACKED ELECTRODE cuit if it were provided with the numbers corresponding to volts, amperes, and phase PROTECTIVE q.- HOLE IN HOUSING in MESH TO PERMIT BACK-FLOW angle; then, following the rules implicit OF AIR this operation, it would yield the answer in watts with as high an accuracy as the MOLDED PLASTIC HOUSING original numbers possessed. The wattage reading, in contrast with the analog watt- excellence of the new polyvinyls and poly- meter, would hold only for the instant ethylenes which can withstand relatively when the original current and voltage ap- high voltages without puncturing. peared. This is the reason why analog ma- The illustration shows the construction chines are said to operate in "real time" type now being installed (answers given at the instant when they of one modern noted the hi -fi "packages." The perforated apply). But it should be that in several which just calcu- copper- backed plate serves as one elec- same digital computer on the lated power consumption may now be used trode and the gold film sprayed busi- foil serves as the other. The to reckon the income tax of a large insulating in its con- polyethylene dielectric carrying the gold ness firm without changes electrode and vibrates struction. It is simply fed different num- film is the flexible which the machine will operate in accordance with the applied audio volt- bers upon ages to produce the sound. with the same high degree of accuracy. Picture a wattmeter being used to figure ANALOGS AND DIGITALS income tax! These rather formidable titles are ap- Thus, analog computers are built to do a plied to the two types of electronic com- specific, highly specialized job while digital puters now in common use. The older of machines can handle any task that can be the two with respect to time of develop- translated into numbers. Analogs, although ment is the analog type. having a much lower accuracy potential r Any information device which accepts than digitals, operate in real time and pro- data in the form of physical quantities, op- answers, even for data that and vide continuous erates upon the physical quantities, may be constantly in a state of flux. For provides an answer in terms of other quan- never its con- simple problems, analogs probably tities according to the rules of digitals because they struction may be termed an analog ma- will be replaced by wattmeter is a perfect are fundamentally simpler in structure and chine. An electrical ma- example of an analog computer because it concept, but the digital computer is the extracts from the electricity passing chine of the future for solving complex, through it information concerning the mag- tedious problems of numerical nature. nitudes of current and voltage, takes into ELECTRONICS 98 POPULAR

AmericanRadioHistory.Com Superior's new Model 670 -A SUPER METER A COMBINATION VOLT -OHM MILLIAMMETER PLUS CAPACITY REACTANCE INDUCTANCE AND DECIBEL MEASUREMENTS SPECIFICATIONS: ADDED FEATURE: BuilfIn ISOLATION TRANSFORMER D.C. VOLTS: 0 to 7.5/15/75/150/750 /1,500/7,500 Volts reduces of burning ouf A.C. VOLTS: 0 to 15/30/150/300/1,500 /3,000 Volts possibility bUTPUT VOLTS: 0 to 15/30/150/300/1,500 /3,000 Volts meter through misuse. D.C. CURRENT: 0 to 1,5/15/150 Ma. 0 to 1.5 /IS Amperes The Model 670 -A comes RESISTANCE: 0 to 1,000/100,000 Ohms 0 to 10 Megohms housed, in a rugged CAPACITY: quityf0alo I 50 ns d -Bad scale tot electrolytic condensers crackle- finished steel REACTANCE: 50 to 2,500 Ohms 2,500 Ohms to 2.5 Megohms cabinet complete with 40 INDUCTANCE: .I5 to 7 Henries 7 to 7,000 Henries test leads and operating DECIBELS: -6 to 4- 16 +14 to +38 +34 fo +58 Instructions. 8NET

SuMperodiorel 's new TUBE TV -11 TESTER SPECIFICATIONS: *Tests all tubes Including 4, 5, 6, 7, Octal, Lock- to damage o tube by Inserting a In the wrong In Peanut, Bantam, Hearin g Aid, Thyratron socket. N Sub Miniatures Sub -miniatures, ovals, -minors, * Free -moving II c h a M ovides corn- Proximity use types. etc. plate data for all tubas. * Uses the new self -cleaning Lever Action Switches * Newly designed Line Voltage Control compen- for individual element testing. Because off ele- sates for variation of any Line Voltage between ments ore umbered according to pin- number 105 Volts and 130 Volts. in the RMA base numbering system, the user Phono panel can instantly identify which element is under * NOISE TEST: -jack on Iront for test- Tubes having tapped filaments and tubes plugging in either phones or external amplifier with filaments terminating in more than one will detect microphonic tubes or e due to pin are truly tested, with the Model TV -II as faulty elements and loose internal connections. any of the pins may be placed in the neutral position when necessary. Is.iió velé°éó * The Model TV -II does not use any combination iuhn

11 type sockets. Instead individual sockets are used for each type of tube. Thus it is Impossible

EXTRA SERVICE -The Model TV -II may type oscillator incorporated in this mode be used as an extremely sensitive Con- will detect leakages a when the ire denser Leakage Checker. A relaxation quency is one per minute

THE NEW MODEL TV -50 ENDMETER A versatile all- inclusive GENERATOR which provides ALL the outputs for servicing: A.M. Radio F.M. Radio Amplifiers Black and White TV Color TV 7 Signal Generators in One! Bee Generator R. F. Signal Generator for A.M. Cress Hatch Generator R. F. Signal Generator for F.M. Color Dot Pattern Generator Audio Frequency Generator Marker Generator

R. F. SIGNAL GENERATOR: The VARIABLE AUDIO FREQUENCY BAR GENERATOR: The Model TV. Model TV -SO Geoometer provides GENERATOR: Io addition toe Bled 50 projects an actual Bu Pattern complete coverage for A.M. sod 400 cycle one-weee audio, the on any TV Receiver Serena Pattern V.66 alignment. Denotes Radio Model TV -50 Genometer provide. e willill consist of 4 to 18 horizontal Frequencies from 100 Kilocycles to variable 300 tide to 20,000 cycle or 7 to 20 eertleel bars. 60 Megacycles on fundamentals and peaked ware audio signal. from 00 Megacycles to 180 Mega- cycles on powerful harmonies.

CROSS NAIRN GENERATOR: The DOT PATTERN GENERATOR (FOR MARKER GENERATOR: The Model TO. Model TV -50 Genmeter will project COLOR TV) Although you will he able 60 Include all the most frequently erns -hals! pattern ao any TV to use most of your regular standard needed marker potpa The following picture tube. The pattern will ma equipment for eeMCtng Color TV, the mane. are provided: 189 Ge., 262.5 eist of non- ealltine, horleontal and one addition which la "must" M Ke., 456 Ka, 600 Kc 1000 Ke., THE MODEL TV50 54 terticel lines Interlaced to provide Dot Pattern Generator. The Dot Pattern 1400 Kg, 1600 He., 2OÓ0 Ks, 2500 coma abaolutely neble craw -hatch effect. projected on my color TV Smelter tube Ke., 3570 Kr., 4.5 Ma, 5 Me., 10 7 fete with shielded by the Model V -50 will enable you to Mr.. 13579 Kc. is the color bunt Ore. leads and Operating NET adjust for proper color enreergenes- Mimes.) Inetrurlione. Only ... SHIPPED ON NO MONEY WITH ORDER -dá u.

Try any of the above in- MOSS ELECTRONIC DISTRIBUTING CO., INC. etruments for 10 days before Dept D -152 3849 Tenth Are., New York 34, N. Y. you buy. 1f completely sat- Please send me the nies streaked. I ogres to pay down payment teams iated Chen send down pay- within IO days endw to pay the monthly balance as shown. le ment and pay balance as In- is understood there will be no finance, interest or any other Address dicated ore coupon. No In- ch rges, provided I send my monthly payments when due le is further understood that I terest or Finance Charges should fail to make payment when due, the tell unpaid balance shall become immediately due Chu Enne.... ente Added! Of net completely and payable. sett/tiled return unlit to ua. 670 -A.Total Price $28.40 Model TV- 11,Total Price $47,50 Model TV 50 Total Price $47.50 Ito esplaee ±ton neeessary. Model$7.40 within 10 days, Balance S11.50 within 10 days. Balance 511.50 within 10 days. Balance $3.50 monthly for 6 months. $6.00 monthly for 6 months. $6.00 monthly for 6 months. J August, 1955 99

AmericanRadioHistory.Com planned are first -run stage hits or new movies, 'special events, etc. In this book, Mr. Kamen explains the OP'tronics three systems that have been developed to provide subscription television. Known respectively as "Phonevision," "Subscriber - Vision," and "Telemeter," these systems are discussed and explained both from the technician's as well as the consumer's standpoint. Suitable photographs and block BO OKSHELF diagrams add to the reader's understanding of the new techniques. Although 4 "BASIC VACUUM TUBES AND THEIR the author is frankly in favor USES" by John F. Rider and Henry Jaco- of subscription TV, his approach is calm bowitz. Published by John F. Rider Pub- and objective. Certainly, it will take as lisher, Inc., New York, N. Y. 204 pages. cogent a work as Mr. Kamen's to refute Paper bound. Price, $3.00. the case for "pay -as- you -see TV." This book is addressed to the general lay reader and the beginning technician. While covering its avowed subject thoroughly "ELECTRICITY" by Eric de Ville. Pub- from a technical standpoint, its style and lished by Penguin Books, Inc., Baltimore, treatment manage to capture something of Md. 159 pages. Paper bound. Price, 65 the "magic" of electronics that has fasci- cents. nated people for more than 50 years. An amazing amount of historical and The first chapter introduces the vacuum technical information is presented in this tube and traces its development from the compact volume. The discovery of elec- first observations of the "Edison effect" in tricity, landmarks in its development, its 1883 to present -day types. Chapter 2 is a uses and modern applications are clearly lucid explanation of electron behavior and explained. The author surveys the field emission in tubes. Chapters 3, 4, and from the early experiments performed at 5 deal with diodes, triodes, and multielec- the court of Queen Elizabeth I down to the trode tubes respectively. For each general electron microscopes of our day. tube type, the authors provide an explana- More than a simple narrative account, tion of how it works. this book actually tells how things happen. Graphs, schematics, and animated car- Subjects treated include magnetism, pow- toon -type drawings supplement the text. A er, heat, light, communication, cathode subject index at the end of the book adds rays, x -rays, radio, television, radar, and to its usefulness. atomic power. Numerous line drawings, 16 pages of photos, and an index add to the book's value. Certainly, this is the best 65 cents' worth we've seen in a long time. "PAY AS YOU SEE TV" by Ira Kamen. CZ, Published by Howard W. Sams & Co., Inc., Indianapolis, Ind. 94 pages. Paper bound. "TV REPAIR QUESTIONS AND AN- Price, $1.50. SWERS ON FRONT ENDS" by Sidney The subject of subscription television has Platt. Published by John F. Rider Pub- caused one of the hottest controversies lisher, Inc., New York, N. Y. 132 pages. raging in the current world of video. Spon- Paper bound. Price, $2.10. sors, artists, networks, engineers, service As an aid to practical servicing, Rider technicians, the FCC,-and the viewing pub- has brought out this compact volume. In- lic at large are all concerned and involved. cluded in it is material on turret -type, The general idea behind this development switch -type, and continuous -type tuners is to get the home audience to pay a fee for television receivers, as well as anten- to see special types of programs, presum- nas and transmission lines. ably non -sponsored and free of commer- The book is arranged as a series of ques- cials. tions and answers. Questions cover typical "Co- existence" between commercial TV problems that arise in the average TV re- and subscription TV is, of course, a possi- ceiver, while the answers provide step -by- bility. The audience may choose to tune in step procedures for correcting defects. a regular channel and see what is avail- Many answers are followed by discussions able, or spend a small amount to operate a of the problems which contain useful hints. special attachment to a set. This accessory, To help locate the answer to any spe- would be a decoding device that would per- cific problem, the arrangement of the mit the special show being telecast to ap- book's chapters is based on the path taken pear on the screen. The "special shows" by a signal entering the TV set. --I - 100 POPULAR ELECTRONICS

AmericanRadioHistory.Com Printed Circuitry (Continued from page 76) Fix your TV Set When all lines have been scored, use the knife to cut between the copper and the base and slowly peel off the unwanted cop- YOURSELF! per. Take this step slowly, since too hasty a pull may yank loose some of the copper wiring. 100% GUARANTEED! BRANDED! SAME DAY SERVICE! When the card is completely stripped, use steel wool to smooth any rough edges on the IA4P 29 68 D5 59 7F8 59 7J7 59 lines. all is to it. Drill the I Al 49 68E6 39 That's there 183 59 6BG6 99 7K7 59 holes required by the layout, using a sharp IB4P 79 6BH6 49 7U5 49 724 39 drill. Lay the copper side up and drill down IC6 29 6BJ6 49 I2AL5 39 for a cleaner hole. Eyelets may now be IC7 29 68K7 69 68L7 69 12AT6 39 put in. I E7GT 39 68N6 99 I2AT7 69 I F5G 29 Mount the components, using the light- 79 12AU6 39 IH5 49 6896 weight soldering iron; snip off the excess 6BQ7 79 12AU7 59 I L4 49 6BY5G 59 12AV6 39 leads. Bring hookup cable through the IL6 59 6BZ7 79 12AV7 69 cable hole and solder to the flea clips or ILA6 39 6C4 39 12AX7 59 eyelets as required. Insert the tube, and I LC5 39 6CB6 49 12BA6 39 ILC6 39 the printed circuit is ready for the test. 6CD6 99 12BA7 59 IN5 49 12BE6 39 If layout is correct and all solder 6CU6GT 99 the IRS 49 6F6 39 12BH7 59 joints have been made properly, the set 155 39 6F7 69 12SA7 49 1T4 should be ready to go. If it fails to function, 49 6J6 59 125K7 49 IT5GT 69 6J8 79 129,17 59 check the solder connections for high -re- 1U4 49 6K6 39 12SL7 59 which malfunc- IUS 39 sistance rosin joints cause 6L6 69 12597 39 IX2 59 tion. 6N6 69 1457 79 2A3 29 There many uses for printed 6S4 39 19BG6 99 are other 2A7 29 658 59 1918 69 circuits in ,R /C and other electronic appli- 3AGT 99 6SA7 49 251306 79 49 cations. For the ultimate in receivers and 304 6SD7 49 25L6GT .... 39 395 59 transmitters, learn how to design printed 65K7 49 25W4GT ... 39 3S4 49 6SL7 59 25Z6 39 circuit bases. They're simple, durable, and 3V4 49 65N7 59 3585 39 conventional - 5U4 39 offer many advantages over 6597 39 35C5 39 5V4 49 type wiring. 65R7 49 35W4 29 5Y3 29 618 69 3523 29 5Y4 49 6U8 69 35Z5 29 5Z3 29 6V6 49 35/51 29 6AB4 39 6W4GT .39 36 29 6AG5 49 6X4 29 37 29 6AJ5 69 6X5 29 39/44 29 6A K5 69 7A4/XXL .. .39 49. 29 6A L5 39 7A6 49 5085 49 6AQ5 49 t- 7A7 49 SOCS 49 6,455 .49 7A8 49 50L6 49 6AT6 39 7AK7 79 75 29 6A U6 39 7B4 49 76 29 6AV6 39 785 49 77 29 687 79 786 49 80 29 (A) 68.46 49 .99 6BA7 59 787 49 II7L7GT ... 6BC5 49 7F7 59 11723 29

Minimum Order $1.00 25% deposit with order. Balance C.O.D. If full remittance is sent. Mail Your order to please include postage. Excess money will be refunded. Quantity u =- el'S- \Veit(' für SUCCI al discouni.! FREE! with every order of $20 or more- famous "0i:- stall" magnetic screw- VIDEO driver kit. Includes ail sizes -Philips head, ELECTRIC COMPANY long handles to get in (s) those tight spots, etc. 7 screwdrivers in all. 79 CLINTON PL. Slay be purchased out- Shown in (A) is the bottom of the printed right. List value $4.89 -$1.99 each 3 for NEWARK, N. J. base of the "Lorenz 61" R/C receiver shown $5.50. in (B). Parts are mounted on the top side.

August, 1955 101

AmericanRadioHistory.Com ; Tp4P1rt.. px. ,19117+'!r1-

Schematic Lingo age wiring is drawn along below the tubes, while high -potential or "B plus" wiring (Continued from page 45) may be drawn along above the tubes. It is hardly possible to follow the window frame for an antenna, these conventions connect in a pictorial. Each pictorial is, hence, the phones, and presto a ... Grandpa Jones, one -shot affair so far as learning goes. But Peggy Lee, news bulletins, and used -car every commercials. schematic understood, preferably re- drawn, and perhaps is If you should accidentally built, a step toward touch the "A a better understanding of electronics. -MI- plus" lead to "B plus," the tube filament will go up like a press photographer's flash- bulb at the Miss America contest. This can be annoying, although not as serious as in Transmitting Tower the old days when tubes cost six dollars apiece. (Continued from page 69) Why "A" and "B" Batteries? the first step in passing any examination. The Radio Amateur's License Manual, $0.50, The terms "A" and "B" for batteries, for published by The American Relay League, the benefit of those youngsters who were Inc., West Hartford 7, Conn., is a complete not playing with radio in the 1920's, goes source information. back when all home of this to the time radio sets It contains reprints of the FCC-suggested ran on batteries. Since "filament" and supply" study guides for the three classes of ama- "plate and such expressions did not teur examinations, complete with answers. ring bells in the minds of the general public, These people with are not the same questions that ap- the battery came up some nice pear in the examinations, but if you can simple names having one letter each. When family radio answer and understand them, you will have the started to get laryngitis, no trouble with the actual examination you opened up top of the cabinet the (they questions. Also included in the manual is all had piano hinges) and looked at the filaments. a complete list of all FCC offices and ex- If they looked dim, you hauled amination points and the dates and times the 6 -volt off storage battery the shelf un- when amateur class examinations are held. der the table and took it out for a recharge. Concluding the booklet is a complete re- If this didn't fix it, you had to run down to the corner radio store print of all regulations governing the oper- and exchange ation of amateur stations. The license eight bucks for a pair of 45 -volt heavy -duty manual is revised frequently to keep it up B batteries. But suppose to date. we end the history lesson Companion booklets to the license man- and get back to 2 diagrams. Figure is a How To Become A pictorial diagram of ual are Radio Amateur, the same circuit as $0.50, and Learning The Radiotelegraph Fig. 1. Now, honestly, do you still think Code, $0.50. The first contains construc- it's simpler than the schematic? tional details for several, low -power ama- Actually, one big trouble with pictorials teur stations and much other information is that the man drawing the diagram has for beginning including brief less choice as to where the amateur, he locates the parts. instructions for learning the radio code. This makes for more of a tangle in the wiring. The second booklet covers the latter more Not too bad for simple circuits like thoroughly. this one, it gets rapidly worse with two - and -tube The license manual is invaluable as a three circuits, and the multiplic- study guide and a source of information ity of crossovers makes the wires hard to follow about the whole amateur licensing picture, without a flock of colored pencils. and the other two booklets are quite help- Wiring Schematic Preferred ful. All three are available in a small packet, The Gateway To Amateur Radio, A schematic, if it is drawn right, will for $1.50. have very few crossovers of leads. Then, Also available from ARRL is The Radio there are standard conventions that help, Amateur's Handbook, $3.00, paper bound. which are followed by almost everyone: It is a complete, one -volume text on the (1) stages are laid out in approximately a theoretical and practical sides of amateur straight line, with the signal proceeding radio. The Radio Handbook, $6.00, cloth from left to right; (2) auxiliary circuits go bound (Editors and Engineers) is some- below the tube they affect, e.g., in a super - what similar in its coverage. Both are good, het the oscillator is drawn below the mix- and any ham shack should contain one or er; (3) power supply circuits are drawn the other. below, near the bottom of the sheet; (4) Another valuable amateur study guide is ground, filament, a.v.c., and such low -volt- the Radio Amateur Questions And Answer 102 POPULAR ELECTRONICS

AmericanRadioHistory.Com wpy '..'ti. , , .' TI . rr ; . ... r '" , . . , '

Guide, $0.50, published by American Elec- will get a chance to display your technical tronics Co., 12031/2 Bryant Ave., New York knowledge. There are no exceptions to this 59, N. Y. Based upon the FCC amateur rule. study guides, the questions and answers in Next month, I shall discuss how to learn this booklet are arranged in the multiple - the code in detail. Here, I will only say choice form used in the actual FCC exam- that it seldom takes more than a few weeks inations. Two simulated "examinations" to master the code and the elementary are included to help the student decide theory required to qualify for a Novice li- when he is ready for the actual examina- cense. However, the average beginner can tion. Most students find this feature de- pass the Technician /Conditional /General cidedly helpful. written examination quite a while before AMECO also offers their Complete Radio he can send and receive the code at a speed Theory Course, $3.95, paper bound, which of 13 words per minute. is a home -study course in amateur radio This is why the Novice license is so theory. The course is complete with many popular. With one, you can be on the air tests, so that you can check your progress and making contacts while bringing your at frequent intervals. code speed up to the 13 -wpm level required These books may be ordered directly for a full- fledged amateur license. from the publishers or from the radio sup- A License ply houses that advertise in POPULAR ELEC- Obtaining TRONICS. The catalogs of the latter list There are several ways to obtain your other books, which you will probably wish first amateur license: (1) you can appear to add to your bookshelf later, but a selec- at an FCC examination point* and apply tion from those listed here will take care for a General license; (2) you can apply of your immediate needs. for a Conditional license by mail, if you live over 75 miles from any point where the Learning The Code FCC holds amateur license examinations at Being able to pass the technical examina- least once every three months* or are un- tion is only half the battle in obtaining an able to appear for a General examination amateur license. Even if you plan only to as a result of protracted illness or being in operate a voice (phone) transmitter, you *See list of addresses in the license manual mentioned must pass the required code test before you earlier.

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ALL -PURPOSE FIL. MYSTERY PACKAGE Kit 3. Volume Controls KIT 7. TOGGLE & SLIDE 2OR.ASS SWITCHES TRANSFORMER ELECTRONIC PARTS R5aange froTEDm2 $75 25 ASSORTED. For Model Trains, Weld. Som: DPST, OMIT. The of Your Life 3wih SPST, ate. wu325 54.95 Ing, Transmitters, etc. Surprise switen. was 34.75 PRI. 117 r. 60 cyc. sec. 20 ponds of Worth $50. - BRAND NEW Our Price Kit 4. Rotary Switches KIT 8. PAPER & CAN GOVT. 6.4 v. 10A USABLE CONDENSERS ASSORTED. `] s v 3A } $ V R P l U S. 25 25 ASSORTED. 5 v 3A TYPES. A Real from 495 Ideal gift for . 95 T50 Range v.m t4 3.5 the ham, 5e. Bay at only. was 54.7$ SO mfd. 450 v. wu 53.50

FIND YOUR KIT PARTS HERR GLOW -LITE -21/2 Watt Argon Lita 110 VAC. 29c MOTOR -From Gun Camera 24 VDC. Will Run on 110 VAC. TRANSFORMER -Pri. 110 V. 60 Cy. Sec. 6.3 V.1 Amp. 85e TRANSFORMER -Pri. 110 V. 60 Cy. Sec. 400 VCT. 6.3 V. 95a S inch Round 1 Amp. 5 V. 2 Amp. 20 Ma. $1.49 CABINET -RCA Speaker Cabinet. Plastie for SCOPE TRANSFORMER -Pri. 110 V. 60 Cy. Sec. 4000 V. Speaker $1.95 10 Ma. $2.95 RHEOSTAT -30 ohm 50 Watt 91e TRANSFORMER -Pri. 110 V. 60 Cy. Sec. 600 VCT. 6.3 V. 3 Amp. 6 V. 2 Amp. 70 Ma. $2.45 RELAY D.P.D.T. -110 VAC. 8 Amp, contacte $1.09 KIT RELAY D.P.D.T. -3 VDC. 11 ohm coil cont. 15 Amp. HI GAIN DYNAMIC MIKE 110 V. Gold Plated 95e Uses UTC. Transformer and Western Electric Mike. Ideal KEY -J38 Telegraph key 95e LIP MIKE -With Head band cord and switch $1.29 for Hams, PA. CAP, Recording, Mobile Equip. CHOKE -2.5 Mh. 125 Ma. 35e -50 DB/80.7500 CPS. T\ CHOKE-1.5 Mh. 100 Ma. 15e Diagram Furnished. COIL -Plug in type 4, 1, 6, Prong Type 29e OUTPUT TRANSFORMER -6V6 to 3.2 Voice Coil 39e OUTPUT TRANSFORMER-P.P. 6V6 to 3.2 Voice 59e TRANSFORMER-50L6 Voice oil 35c HERSHEL RADIO CO. Dept. M DOWN-Bal. CHOKE-AC.-DC.R S L6 to 3.2 orcó5wsIh COIL- Ignition Type. Pri. 3 V. Sec. 16,000 VDC. Ideal 5245 Grand River. Detroit 8, Mich. C.O.D. for Photo Flash Triggering $1.29 NO ORDER LESS THAN 82.00- SHIPPED FOB DETROIT

August, 1955 103

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the service of the United States and being to the FCC office from which they were re- prevented by your official duties from ap- ceived in the envelope supplied for the pur- pearing for such an examination -in either pose. of the latter events, your application must In about a month, your new license will be accompanied by an appropriate certifica- arrive through the mail, unless you have tion from your doctor or commanding offi- failed the written examination. Do not be cer; (3) you can apply for a Novice or overly discouraged, if this occurs. You can Technician license by mail only. try again, after 30 days have elapsed, if To apply for any amateur license by mail, you fail either part of the examination. write to the nearest FCC office and request You choose your own code examiner for the material for the class of license you the "by mail" examination. He must hold are interested in. By return mail, you will an amateur General, Advanced *, or Extra receive an application blank (form 610), a class license; or- within five years of the sealed envelope containing the written ex- test -have held a commercial radiotele- amination, and full instructions. graph license issued by the FCC or have You then fill out the application blank been employed in the services of the United and have it notarized. Next, a volunteer States as an operator of a manually oper- examiner gives you the code test and states ated radio -telegraph station. on the application form whether or not you Most amateurs are happy to act as code have passed it. If you have not, the exam- examiners for the tests. Also, many ama- ination stops there, and the application teur clubs have licensing committees for form and the unopened envelope of ques- thq purpose. If no other arrangements can tions must be returned to the FCC office be made, the FCC will appoint a code ex- from which they were received. aminer. Assuming that you do pass the code test, The witness to the written examination someone opens the sealed envelope and must be at least 21 years old. If he meets hands you the examination papers. After this requirement, the code examiner can act in both you complete the examination, he states on capacities. Going back the application form that you did so with- a bit, you can apply for both out help. Finally, the examination papers and the application form are *The Advanced license is no longer issued, but many mailed back amateurs still hold valid licenses of this class. LIFETIME GUARANTEED TUBES BRAND NEW PICTURE TUBES We guarantee to replace tubes labeled MAJOR BRAND forever Each Tube Individually Boxed And Guaranteed For Life Over A Half Million Tubes RCA Licensed. diate Shipment Always In Stock Imme- One Year Unconditional Guarantee. 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Worth M- 044-E -Y Clip out this ad and attach it to your order. Three 6SN7GT's will be shipped F5$5 Please include approximate postage on With any order of more, foreign shipments. All orders subject to $10 or sale. Add 25f handling on orders prior $5.00 . Quantity users write for special discount. Write Write For FREE Tube List -Order Blank Opt. MAJOR BRAND TUBE CO. -and FREE Sample Tube Carton. We 8 PE want Y -O-U On Our Mailing List! Romano Bldg. ESsex L 4 -1106 Harrison, N. J. 104 POPULAR ELECTRONICS

AmericanRadioHistory.Com the Novice and Technician licenses at the As Much As same time, or you can first obtain a Novice license and later obtain a Technician license. Carrying the thought a step further, if you hold a Technician license and are 50% eligible for a Conditional license, you can obtain it by passing the 13 -wpm code test. SAVINGS If you are not eligible for a Conditional license, you will not have this latter option. With WRL! Even if you already possess a Technician Here's license, you still must take the entire examination when applying for a General wrcQv Just A Few license. Fortunately, if you can pass the In our stack of over 600 reconditioned Items, protected written examination once, you certainly can by our 90 day, New guarantee ... and of special inter- do it again. est to beginners! Incidentally, the procedure for taking Heath AT -1 (CW) Xmttr. $24.95 the General examination is practically the Hallicrafter HT -17 (CW) Xmttr. 29.95 same as that for the "by mail" examina- Lettine 240 (Fune and CW) Xmttr. 49.50 tions, except that it is given by FCC exam- Stancor ST203A (Fone and CW) Xmttr. 29.95 iners in an FCC office. Stancor ST202A (CW) Xmttr. 79.00 Hallicrafter S -38, S -38A 27.50 Hallicrafter S -38C 35.00 News And Views National SW -54 29.95 Each month, this part of the Transmit- Send for our complete recond. equipt. list today! ting Tower will contain news for and about "It's Easy to do Business with WRL!" you. Write and tell us about your amateur experiences. How many states and how worked? much DX have you What kind of EVERYTHING IN HI -FI EQUIPMENT! equipment do you use? What is your favorite band? What would you like to know Players * Amplifiers * Tuners * Speakers about other amateurs? Microphones * Tape Recorders All letters received will be carefully read "Personalized Engineering Service" and, to the limit of the space available, the Send for FREE Hi -Fi Booklet ... TODAY! more interesting ones will be printed. To permit using more of them, those selected will be condensed where possible. 65 watt In addition, the column can use good, GLOBE SCOUT sharp pictures of you and your equipment Completely similar to those used this month. Prefer- Bandswitching will be given to pictures of simple ence The ideal transmitter for novice or stand- installations; however, an occasional pic- by Xmitter. Fully bandswitching. 160 only thru 10M.. 65 watts CW, 50 watts on ture of a "de luxe" amateur station will be Cone. Metering provided. PI Network antenna tuner. Self- contained power sup- $7.95 printed to give those just starting out ply. May be used mobile; provisions for per month dynamotor attachment. 1000/0 modula- Pay $10.00 Down something to dream about. tion of Final. TVI screened cabinet. In keeping with the theme of this first Compact; e "x16 "xe ". Cash: $99.95 column, I am including the addresses of IMMEDIATE DELIVERY two radio clubs that conduct regular classes PE-8 to help prospective amateurs obtain their WORLD RADIO licenses. They are the El Ray Radio Club LABORATORIES and the Watauga Amateur Radio Club. v.OR .11010 .1:111'111111 For information on the El Ray Radio 11111 I:í .Club classes, contact Bill Welsh, W1SAD, ''The World's -Most Personalized Radio Supply House" 1228 Cambridge St., Cambridge 36, Mass.; IPlease rush me your: this club turns out 20 to 30 new amateurs FREE 1955 Catalog FREE Hi -Fi Booklet a month. For information on the Watauga IAnd full information on: Amateur Radio Club classes, contact Mark Globe Scout Wall Radio Map (25c1 C. Green, KN4ARZ, Secretary, Box 582, Reconditioned Equipment List Johnson City, Tenn.; new classes start ev- Address to: ery three months. 3415 W. Broadway Council Bluffs. Iowa Future Transmitting Towers will publish 1 the names of other clubs and individuals IName: offering help to prospective amateurs. I'll be waiting for you on the same cor- Address: then, 73, Herb, ner next month. Until City and State W9EGQ. - owl August, 1955 105

AmericanRadioHistory.Com 4'1".!4"0"airgir ,RRIi"ii` a °AM!TPl!iIr

than the insulation on the wires themselves. For further information, write to TOOLS the manufacturer, Ideal Industries, Inc., Sycamore, Ill.

CIRCULAR SLIDE RULE A circular slide rule, designed for users GADGZI5 with limited mathematical training, has MORE HEAT FROM SOLDERING GUN been announced The new "Primax" soldering gun reaches by the Lithocal- soldering heat in less than six seconds. culator Co., 31 Rated at 60 watts, it is said to provide St. Joseph St., heat equivalent to 120 watts. Another fea- Arcadia, Calif. ture is its unbreakable plastic handle. Computations Weight of the new gun is 1 lb., 11 oz. The are made by alloy tip of the "Primax" requires no filing dialing in the and is said to last indefinitely in normal numbers with a movable cursor. The answer never runs off the scale, and is always read at the same stop position on the "Answer Dial." Trigonometric scales are included on the back. This unit retails for approximately $10.00. For further information write to the manufacturer. "TWISTUBE" FOR COLOR TRANSMISSION use. Wiping it with a rag or paper re- With the advent of color television, the stores its tinned luster. Grip and trigger question of adequate antennas and trans- control are balanced to provide for con- mission lines is beginning to take on added venient operation. Furnished in a pouch, importance. Interference and ghost images the gun is available for either 110 volts or 220 volts, a.c. For further information, write to the manufacturer, Paul C. Roche Co., Inc., 11 Park Place, New York 7, N. Y. INSULATING CONNECTOR Insulated joints between wires are made quickly and positively with the Ideal crimp connector which is furnished with "Wrap - Cap" insulation. It has two parts: a sleeve and an insulating are even more disturbing in color recep- cap. Both parts are listed tion by Underwriters' Laboratories, Inc. for gen- than in black and white. "Twistube" eral use in branch circuits and fixture wir- is a new type of transmission line especially designed to reduce interference pickup automatically. "Twistube" is transposed around a star - shaped air -spaced former to equalize the capacity of both conductors. It is said to give perfect reception-whether for col- or or black and white -in distances ranging up to 105 miles, even under the most difficult fringe area conditions. It features uniform low capacitance and attenuation. "Twistube" is manufactured by Fenton Company, 15 Moore Street, New York 4, N. Y., and is distributed through jobber channels.

SPRING WINDER A HANDY TOOL ing. No tape is required. This new connec- A versatile tool is the new "Speedex tor insulates all around the joint and be- Spring Winder," developed by General tween the wires. The resulting insulation Cement Mf g. Co., 919 Taylor Avenue, is said to have a higher dielectric strength Rockford, Ill. Claimed to lfie very easy to 106 POPULAR ELECTRONICS

AmericanRadioHistory.Com sT;+o . p+::..yyu let

use to make any desired spring, this novel without shutdowns or ammeter connec- device should find a growing acceptance by tions. It is also a voltage meter which tool rooms, maintenance departments, ex- gives an accu- perimental or engineering groups, and rate voltage automotive mechanics. reading on a Any type of spring, any number of coils full -size 1.8" ca- and any pitch desired can be turned out librated scale. on the spring maker, using any size wire Accuracy for and forming any diameter spring. Also, both amperage both compression and extension springs are and voltage is possible. The winder fastens to any bench, within 3% and a simple screw adjustment varies the of full scale. pitch instantly. The user can The "Speedex Spring Winder" (Cata- choose the logue No. 5209) carries a net price of model that fits h i s particular job. Ranges are available up to 100 amperes, a.c. and 250 volts, a.c. Other features include a 3" d'Arsonval high - torque movement with an Alnico 5 magnet. Probe jaws are completely insulated, and tapered for hard -to- get -at $14.95, complete with an assortment of wires. Transformer joints are dove -tailed. spring wire. Additional information is The meter is pocket -sized and is shaped available from the manufacturer. and balanced for one -hand trigger operation. To measure current without ammeter SNAP- AROUND VOLTAMMETER connections, the device's jaws are snapped The "Amprobe Junior" is a snap- around around one conductor (insulated or unin- ammeter that measures current instantly sulated). To measure voltage, the test FREE! $7.20 list value Bonus Boo of three SON] andd 25 assorted TUBES resistors with each TELTRON more. order of $25 or GIFT OFFERS SAME DAY One 6BG6G tube SERVICE Guaranteed! Lowest Prices Ever! will be shipped hour De- FREE with any lilivery ver to We st I Coast $10 order accom- guaranteed for one year SPECIALS! All tubes individually boxed ... unconditionally panying this ad. Till September 1 Type Reg. Special 024 .45 .59 TYPE PRICE 1B3GT .62 TYPE PRICE TYPE PRICE TYPE PRICE TYPE PRICE 1135 .51 .47 6AT6 .37 6176 .59 7N7 .52 25W4GT .43 354 .48 .44 FREE 1A7GT .53 .43 .39 1H5GT .51 6AU5GT .60 6E5 .60 12AT6 .37 2525 .55 5U4G .36 GAGS .52 .48 BONUS 11.4 .51 6AÚ6 .43 6F5 .44 12AU7 .58 2526GT GALS .43 .38 1L6 .51 6AV5GT .60 6F6 .42 12AV6 .42 35A5 .48 68A6 .56 .45 6H6 .50 12AV7 .73 3585 .48 6BQ6GT .83 .72 1LC6 .49 6ÁV6 .37 .61 .42 OFFER! 1N5GT .51 6AX4GT .60 6J5 .49 12AX4GT .60 35C5 .48 6J6 120X7 .61 35W4 .33 6K6GT .39 .35 155 .43 6AX5GT .60 685 .60 .42 6SN7GT .60 .55 1T4 6BA7 .58 6K7 .40 1204 .72 35Y4 6V6ß7 .48 .42 .51 32806 .46 3423 .41 .43 .35 11.14 .51 6BCS .48 6L6 .78 6W4GT 12807 .5e 35ZSGT .33 12ÁT7 .71 .66 lus .43 68C7 .75 607 .40 12AZ7 .61 .54 1X2 .65 6BE6 .46 654 .41 126E6 .46 37 .59 .49 128X7 .61 43 .55 125N7GT .56 305 .65 6BF5 .48 6SBGT .65 25L6GT .41 .37 .48 6907 .45 12BY7 .65 45 .55 35L6GT .41 .37 304 .53 65F6 .49 LOGT .50 .45 30567 .61 6BGGG 1.18 6587 .45 12H6 .50 50A5 50 12J5 .40 SOBS .48 3V4 48 68X6 .51 65J] .45 NEW LIBERAL 5R4 .95 6BJ6 .51 6SQ7 .40 12K7 .40 50X6 .53 TERMS! .44 No minimum order. 5V4 .49 68K5 .75 6T8 .73 1247 .48 75 32507 .4S 77 .55 All postage paid on 5Y3 .30 68K7 .78 OUR .76 orders over $10.00 inn Model 625K 574G 37 6B1.7GT .78 6V3 .80 32517 .45 g0 .40 U.S.A., A.P.O.'s and Ilium. gear-driven OAR .40 6BN6 .90 6W6GT .53 84 .46 Territories. 10% de- 12587 .45 "Speed Rollchart" 6AB4 .43 6BA7 .85 6X4 .37 117GT 1.20 ooiCanadour á n and for- 6ÁC7 65 6BY5G .60 6XSGT .38 12507 .38 117L7GT 1.20 eign friends. Please, New lever- action 3407 .43 switches fol in- 6AH4GT .65 8827 .95 6X8 .80 117N76T 1.20 send approximate 6ÁF4 1.02 .41 676G .61 1486 .36 excessxcess ill dividual testing 6C4 117P7GT 1.20 be refunded. Orders OAKS .96 6C5 .46 706 .46 1407 .52 to sale. nt every element 19006G 1.48 117Z3 .33 subject prior 6ÁQ5 .48 6C B6 .51 7C5 .44 WE WANT NEW Tests all conven- 6AR5 .48 1.63 7F7 .59 1978 .71 11726GT .65 TV 6CD6G ACCOUNTS tional and 6Á4S .52 6CÚ6 .95 7F8 .77 250Q60T .82 1629 .39 If you are rated,your tubes credit is good with us. dis- Rico Tube Tester not We are 'Eieo" This We have thousands types there. On ordering types tributors. Write us is yours FREE When take ] Ha mum list Ptotelis of about special deals on you buy $199 worth ut test equipment. tubes or more within 011 days at Ten row May be bought outright from Teltron TELTRON ELECTRIC COMPANY for $34.95. HARRISON. N. .1. 428 HARRISON AVE. DEPT. PE -8 Phone HUmboldt 4-9848

August, 1955. 107

AmericanRadioHistory.Com fsf(Xt-,41/n11,1*W tTF;:`t%,-''ríi' ,.-i!.IA!?71ì. 0 R4EF i;! f-41 (¡-"rs.SiJìiVt.t;4i4444 r., .. 4111411117111

leads are plugged into the instrument and This magnifier is light in weight and can clipped to the load. For additional in- be easily carried in a pocket. Retailing formation, write to the manufacturer, Pyr- at $3.50, it is made by S. B. Logan & Co., amid Instrument Corp., 630 Merrick Rd., Genoa City, Wis. For descriptive literature, Lynbrook, L. I., N. Y. 30 or to order, write direct to the manufacturer. POCKET -SIZE MAGNIFIER The "Precision- Vision 5 -Power Magni- LOW -COST MITER fier" consists of: an all- aluminum frame- Announced by the Dresden Manufactur- ing Co., 2375 Walnut Ave., Long Beach, Calif., the "Tru -cut Magnetic Miter" is said to be both lightweight and accurate. This new miter, designed for the do- it- yourself home it 410 handyman and professional carpenter alike, is priced at $2.95. It embodies many t' features heretofore found only on more ex- 4

e' e- - w, E 2" in diameter and s/," in thickness -in a black crinkle finish to eliminate reflections; and two individual optical -ground, polished, 17/s" lenses. These lenses are press -locked into ingenious mountings, making them absolutely dustproof and breakage- resistant. The two lenses are separated by an air pensive miters. Easily adjustable to any space, precision -set to bring about powerful angle, it can be folded to pocket size or left magnification. on the saw blade. - ,,,t,,ti!s,ucl SAVE UP TO 90% OFF LIST PRICES For dollar tubes parts or You'llpendeforFREE ON PARTS and TUBES a oupan deemable for gifts! These gifts All tubes individually Electrical Appliances, etellaSe boxed own home or seit All tubes RTMA guaranteed TYPE PRICE TYPE PRICE TYPE PRICE TYPE PRICE them in your Send for them over the counter! one full year 6A55 .50 6507 .43 12SL7GT .69 FREE it Same day serein. 183QT .79 6A56 2.00 65147 .45 12SN7GT .60 for Butbetterr yet place 1L4 .56 6A57G 2.25 6517GT .4S 12507G7 .44 LOGUE ... Several or one of these brands 1L6 .60 order NOW. will be supplied on your BATO .40 651(7 .50 14AS .59 able order 1LA4 .66 6AUSGT .70 6SL7GT .70 14A7 .45 Yngrthese Hallicrafters, Admiral, 1L64 .66 64116 .46 6SN7GT .60 1406 Stewart- Warner, Zenith Emer- 1LC6 .66 son, Philco, Stantron, Crosiey, 6AVSOT .85 65ß70T .44 .52 1 Y 11.05 .66 C I % 1 I 1 t l' 6Y íY C/ í 6AXSGT .S9 6V6GT .48 1913060 1.18 i íl ín Motorola, Sonora, American, 1LE3 .66 i í 6040 .90 6W4GT .40 19.16 .66 M unto. 11.04 .66 6646 .49 6W0 .60 1978 .70 LLH4 .66 6005 .55 6W6GT .56 25A7GT 1.50 PARTS SPECIALS TILL SEPT. 1ST T 1LN5 .49 60E6 .50 6X4 .35 25AVSGT .80 Tube 1NSGT .55 Picture Tube 4" PM RESISTOR KIT 6006G 1.18 6X5 .39 25006 .98 21" TV SET Specials ! íR4 .66 6BH6 .61 6X5GT .35 25606G7 .90 BRIGHTENER SPEAKER 100 asstd. re- IRS .67 6x8 .75 25Y5 .45 Lots of 3 $1.19 With Matching sistors in most TABLE MODEL TifiAug.1 154 .65 6BK5 .70 6V6G .63 2525 .38 Output Trans- wanted oh ms. 155 .65 744 XXL .47 25Z6GT .42 former. Alnico RMA coded in Beg. $149.95. 157G 66K7Á .78 $1.29 1TSGT 1T4 .65 6BN .59 7A5 .55 35AS .48 5 magnet. Out- 1 /a, 1, 2 watt. lus .50 OBL7GT .77 7A6 .47 3565 .52 put transform- List $12.50! 1V .57 .88 .45 35C5 .51 er matches 99f ea. Kit. 3Q4 60ß6G7 Unconditionally 5OL6 etc. 1X20 .79 BBQ7A .80 7A8 .46 35L6GT .48 Guaranteed! 3S4 2021 1.00 6BZ7 .90 7B5 .41 35W4 .39 1.57 $115 8ÁQ5 2V3G .80 .60 707 .43 35Y4 .40 CONDENSERS 1.00 BBYSG .41 70* COSINE CERAM ICON 6AV6 2X2A 708 .47 3523 Molded 306 .4S OCS .38 7C4 .40 3525GT .39 Tabulars, YOKES KIT AC -DC SUPER - 7E5 .52 Popular TV de- HET JEWEL 3LF4 .80 6C6 .50 7C5 .44 SOBS .001 MFD- Assortment of 5055 BCBB .55 7C6 .45 SOCS .51 flection yoke. 50 ceramic con- 5 -TUBE RADIO 600 V 100 ea. New cosine type densers. Popu- 3QSGT .63 6CD6G 1.18 7F8 .70 501.6 .48 Lots of 10, for anti-anastig- Terrific buy! 3V4 .65 6136 7Y4 .36 SOLOGT .45 8C ea. lar sizes. List ST4 .70 E5 .á6 12576 .46 matic focusing. pice$10. Special Stanley 5U4G 49 106 .40 12AT7 75 .44 .01 MFD- Complete with Iota off 5. price! Reg, list 5V4G .71 .46 77 .39 600 V 12e ea. 39c 6H6GT .40 12AÚ6 leads. List ea. price $22.95! 5Y3GT .39 614 2.00 12AÚ7 .60 78 .39 Lots of 10, $10.30! Singly $1.99 EACH .46 7 100 ea. 5Y4G .43 6J5GT .40 12AV6 $2.99 ea. $14.95 .., 523 .47 616 .49 125X7 .70 80 .35 524 .S4 6.17 .45 1211117 .90 83V .60 with each $25 or more or- 647 .59 6K7 .40 120A6 .48 117L7GT FREE 6A8 .59 6K6GT .39 1284 .70 2.00 der! 5 -Pc. Sylvania Repair 6A04 48 6L7 .44 12E1E6 .50 117N76T Kit. Value $4.95. Includes, flashlight head, 60í4 no 687 .61 120117 .70 2.00 6AG5 .56 6Q7 .45 120Y7 .68 117P7GT Philips screwdriver, flat head screwdriver, 64116 .80 6S4 .46 12557 .52 2.00 alignment tool and polystyrene case. OAKS .80 6670 .47 12ÁH7 .47 'ALS .44 6SA7GT .50 125J7GT .50 117Z3 .37 6AL7GT .70 65C7 .50 1251(7 .50 117Z6GT .65 EVERY order r.gardlesa of size! Combination alt FREEwithof mndens.n, volume control and line cortls- retail value $2.95. Special Purpose Transmitting and Cathode Ray TUBES Send for parts and tube listing. tanle% ELECTRONICS CORP. 25% deposit required on all orders, balanoe COD. TERMS: Orders under $s.00, $1 service harge. Postae. paid in USA on all orders accompanied by cfail remittance. 935 MAIN AVENUE - PASSAIC, N. J. All unused moony refunded with order.

Depte . GR, yory OPEN ACCOUNT TO RATED FIRMS PE - 1 -2498

IOR POPULAR ELECTRONICS

AmericanRadioHistory.Com BUILD YOUR OWN GEIGER COUNTER TIPS an ;, with ALLIED'S exclusive TECI1111Q1Et SUPER -VALUE KIT!

NEW USES FOR TV CONNECTORS Small polystyrene plugs and sockets used for connecting TV transmission lines can be handy aids to the radio builder and experimenter. The photo shows how a pair of them may be stacked and fastened to a it's easy to build this low -cost KNIGHT breadboard by a thin aluminum strip. Thus URANIUM LOCATOR & RADIOACTIVITY DETECTOR mounted, they serve as a receptacle for the which is another pair held to- Get started in uranium prospecting now with power plug, this extremely sensitive instrument-compar - gether by cellophane tape. This method of able in quality to costly equipment, yet easy to build at only a fraction of the price. It's simple to operate; just turn it on, flip the high voltage switch and listen to the clicks in the headphone when you hit a radioactive source. Uses low - cost long -life batteries. Kit includes all parts, case with handle and leather shoulder strap, tubes, 22% and 1.1,6 volt batteries, AEC prospecting booklet, radioactive sample and headphones. Complete instructions. 6N x 5% x 23j". Shpg. wt., 2M lbs. More sensitive than units selling at several times this low price. 83 S 242. Geiger Counter Kit. Only $15.95 80 J 663. Extra Battery Kit. Only $ 1.07

pairing plug and socket provides correct ALLIED'Sú BIG-VALUE polarization. EMEN Another use for these units is in conjunc- Send big tion with headphones. Frayed ends of head- cked with ment p releases phone cords are often difficult to attach to values and kits, Hi h Fidel- in these TV plugs ¡ builders' a plug. The setscrews in andd com- will hold the ends neatly, and the other systems A third ponents, P.A. Y half of a plug can serve as a jack. test instruments, use is for plugging in meters. Cheap and recorders, electronic TV accessories, tools. readily available, these plugs provide for tubes and wherever parts, from quick and easy shifting of leads Save money -order largest stocks necessary. the world's of Electronic supplies. "THIRD HAND" FOR SOLDERING Small metal components, plugs, adapters and connectors are notoriously hard to solder. They tend to slide all over the work- every touch of the soldering bench with 79 -H -5 iron. If they are clamped in a vise, the ALLIED RADIO CORP., Dept. heavy mass of metal absorbs too much 100 N. Western Ave., Chicago 80, III. heat, resulting in weak "cold" soldered Send FREE ALLIED Supplement No. 148. hand" joints. An easily assembled "third Send Kit No. 83 S 242 $ enclosed. that will make small parts soldering a cinch in photograph on page 110. is shown the Name A 10" x 12" piece of plywood or hard- a 4" 6" board is used as a base. Mount to Address section of 1 x 2 stock in the center of the baseboard, using either wood screws or City Zone State nails and glue. Two spring -type wooden J August, 1955 109

AmericanRadioHistory.Com 1'.-i , ? x »..itue' :4_,i "Ra18;"V?,N!Ñ

clothespins are attached to the block with MAGIC of remote For model airplanes, boats, cars, etc. RADIO CONTROL wood screws. One is aligned vertically and GYRO RADIO CONTROL TRANSMITTER 27.255 Mc. the other horizontally. Don't use plastic Most POWERFUL 5 Watt TRANSMITTER-LOWEST' -' PRICE. Famous 2 Tube MAC II circuit, with GYRO clothespins they'll melt with the ap- MAGIC TUNING INDICATOR. Completely Tested in- ... eludes: 91/2 1m ft. sect. Antenna. Remote Clicker" key. I plication Switch. Meter, Gnd. Plane Booster, Meant. Cabinet li of heat. 12x7x6. Available in the following models: GYRO X1 TRANSMITTER: As described with To solder a small part, clamp it in one Built-iniilt -in 2V Storage Battery Including Vibrator of the clothespins and apply the soldering ingROyX2eTANSMITTER:R Ac Decor. ;;;ICtrleint.$39 in Dynamotor to OP r. from BV Auto Battery 33.95 iron, flux and solder. Wood is a poor con- GYMO X3 TRANSMTR: 1 tube for dry bty. oper. 23.95 RADIO CONTROL TRANSMITTER & RECEIVER-KIT-2714 Inc Band -License Free. All Parts & Diegr. (leas tubes at crystal) to build Powerful 5 Watt Transmitter Unit & t Tiny 2 -Tube Receiver & SIGMA RELAY $9 s 95 LORENZ 2 -TUBE RECEIVER KIT with Tubes and Relay.. 13.95 SIGMA 4F RELAY: 8,000 ohm. $4.25; R/C Escapement.. 3.95 89 DYNAM. 250V/65Ma $8.95; 2V Vlb. Kit 1SOV /35Ma 8.95 3 TONE MODULATOR KIT -Converts any RC Transmitter to work SAFFORD RECEIVER. with tube and tnetr...... 5.85 McENTEE's RADIO CONTROL HANDBOOK "...... 2.25 O CRYSTALS: 27,255 Mc. Petersgn Z9A $3.95; HOLDER., .15 O.E. RELAY CONTROL: with s ne 10.000 ohm relay.... 1.25 Small AMPLIFIER ASSEMBLY inel. DPDT Relay -Mint Pot & Chassis. Audio Transf., Resistors, Condensers, etc.... 1.25 GEIGER COUNTER KIT $29.95. Wired & tested 39.95 32 ft. steel sect. ANTENNA, $8.95; RCA PHOTOTUBE .95 TUBES: Lowest Prices. XFG1, 11E61, 3A4. 3445, IAG4, 154, Clockword ELECTRIC TIMER: 1/2 min. to 24 min 1.00 TRANSISTORS: New Top Brnd, P.N.P., $2.45. New DIODES .45 BOOK: TRANSISTORS" by Turner 2 00 GENERATOR: 12 -24 V DC. 13 amps. Requires 1/8 h.p or larger motor with pulleys, $6.95; Pencil Soldering Iron 1.95 Storage BATTERIES: Mini 8V. NT8 $2.45; 2V. 27 A /H 2.75 Lifetime NICKEL -CAD Storage BATTERY 3A /HR 8.90 2.8 Volt CHARGER KIT 4.95 ALL MATERIALS GUARANTEED -FREE CATALOG "P" Save C.O.D. fees, include postage, excess refunded. GYRO ELECTRONICS CO. 325 CANAL STREET W., NEW YORK 13, N. Y. l > z9á ductor of heat and won't draw heat away 38 DO -IT- YOURSELF KITS from the part, yet the clothespin will hold Transparent Multi -chassis supplied with all components for building Radio, Intercom., R /C, Phono-ampl., SW- Broadcast the part securely in place until you com- Rec'r- Xmit'r. relay & neon units. No soldering-no drilling - nothing to buy except batteries. Write for catalog. plete the job. If you have a good deal of SPECIAL KIT COMBINATION: -Teat radio & TV tubes and components; trace shorted, intermittent, pen leaky capaci- heavy soldering to do, you may find tors, transformers, flyhacks, resistors, etc. Pictorial wiring that diagram. Test leads, chassis, neon & 3A5 tubes included. Corn plete, with instruction book. You're in business for $3.00 ppd. the clothespins will char slightly. But don't AMACCO worry -there is little danger of fire as long 252 Greenwich St., New York 7, N. Y. as you don't solder with an open flame. -- And clothespins are cheap! VHF AM- FM RADIO LIGHTING GAS TORCH Propane gas torches are used for many Supersenaltive sub-miniature tube set receivesceives televielon. FM broadcast, CAP, and amateurs without antenna or ground. Tunes from 75 mc. to jobs, but often are somewhat difficult to 150 me. Similar models available in frequency bands from 27 me. to 225 mw Pocket glee- measures only 2" x 2 ". 2% ". Highest quality com- light and get started with an ordinary ponent. used Specify battery or AC model. Use with any magnetic headphone or can be connected to audio amplifier for loudspeaker operation. match. A well -filled cigarette lighter, Thousands in use by amateurs. experimenters, and civil defense. Factory as wired hassle complete with special tube only 13.90 postpaid. Postage extra shown, will hold on COD orders. a flame beneath the torch SPRINGFIELD ENTERPRISES Box 5í-E Springfield Gardens 13, N. V. MOVING? Please advise our CIRCULATION DEPT. 64 E. LAKE ST., CHICAGO 1, ILL. Include your old address as well as new -enclosing if possible an address label from a recent issue of this magazine. Allow at least 4 weeks for change of address.

111101.0 CREDITS PAGE CREDIT burner longer than a match, getting the Panellit, Inc. torch Micromatic Honing Corp. burning well, without danger to the _ i The Sheffield Corp. fingers. 25 F J Stokes Machine Co., Inc. 31, 32, 33 Underwriters' Labs.. Inc. MAKING "OPEN" TRANSMISSION LINE 28....Top, Minneapolis -Honeywell Regulator Co. Bottom, Edo Corp. The most efficient type of transmission 29 Top, Bendix Aviation Corp. line is the "open" variety, so called because Center, RCA Radiomarine Corp. of America Bottom, Raytheon Manufacturing Co. it is just a pair of wires kept to a uniform 34, 35 American Heart Association spacing by a minimum of insulating sup- 37, 38, 39 Bell Telephone Laboratories 79, 80, 81 Electro- Voice, Inc. ports. You can see how it works with line 84 Right, The Heath Co. made out of some wire and a collection of Left, General Radio Co. plastic curlers from a home permanent - IIO POPULAR ELECTRONICS

AmericanRadioHistory.Com t!,an KR5-1

ized with open line. If a "high- impedance" antenna, such as a "rhombic" is used, operation should be improved over conventional line performance in all weather, due to better matching. ALLIGATOR CLIPS ACT AS CLAMPS Alligator clips may double as clamps on small gluing or cementing jobs. The photo shows four clips holding the cardboard ring

wave kit. No. 18 enameled wire will work for an open line used for reception or low - power transmitting. Its diameter, .040 ", is just right to slip snugly through the notches in the ends of most curlers of this type. If the hole is obstructed, ream it with a #60 twist drill. To assemble the line, secure the two wires on nails driven 2" apart, stretch out that has been recemented to the speaker the desired length, then string on the plas- frame. These clips may be similarly used tic "spreaders." To hold the spreaders in on small pieces in model making. place, use a dab of polystyrene cement on each end. The "characteristic impedance" QUICK CONNECTIONS will be about 550 ohms; and In experimental work, it is often neces- of this line wires, although this will not match the usual TV sary to connect phone cord tips to a great improvement lugs, terminal screws, and so on. Quick antenna or receiver, way in stormy- weather reception is often real- and secure connections are needed. One HEADQUARTERS FOR

H ARI) 'l'O GET PARTS FOR KITS OW WE HAVE 'l'ITEM! MAKE YOUR OWN NEW! LORENZ R/C RECEIVER PRINTED CIRCUIT KIT WITH PRINTED CIRCUIT NOTHING ELSE TO BUY! with Our Inexpensive Etched -Wire The new LORENZ R/C Receiver Kit Kits Contain: Laminated Cop- PRINTED CIRCUIT BOARD. Complete kit RK61 tube. Sigma Relay, per oilBrds with Raytheon other aTubel Socketts Copper Printed Circuit Board: Chassis and all Etching Material and instruc- parts as described In POPULAR EI.EC tions: Etch -resistant material p as EC for Circuit layouts; Eyelets K T-52 and drill for connections: UM. Scaled Layout Sheets for making standard Iltl'.AZ R. TRANSMITTER KIT Ciccone. All Kits Are Supplied with Plastic Case Complete parts, tube. crystal and batteries as described December 1O'4 POPULAR ELECTRONICS. 5001P -BASIC KIT 5003P- SERVICEMAN KT-54 Net 19.75 Contains a complete assort- & TECHNICIANS' KIT e t of materia s n eded to U Contains three limes the mate- make a variety of different of Kit 5001P with special RADIO KITS Printed Circuits. Circuit Dia sockets Connectors and TRANSISTOR grams include Multimeter and double -faced Copper HoLrds. t tube Receiver TRANSISTOR RADIO RECEIVER KIT: Only 1 .02 Mfd Only e 9.75 Condenser; 1 Crystal Diode IN04; 1 2 -gang Variable I Loop- ® 1 C.E. IN107 Transistor; Condenser, 1 220K Resistor; PRODUCT DESIGNERS' KIT 1 Ear Phone 5004P- stick; Dynamic special Kit enables the Manufacturer and Laboratory tu KT-51 Net Mg This Printed n(ole ,Di.. staff and facilities Conttains all the information. of TWO TRANSISTOR RADIO RECEIVER KIT and methods fur adapting your product to mass product 1, eh- I Lnopstick;l2 -gang Variable Condenser; 2 G.F. 2X107 Mimes. Volume Control Transistor 25.00 Transformer 11 1OOK Ii 10 mfd cCondenser i Dy amie Ear Phone. CDS-PHOTOCELL KIT KT -50 Net 9.74 with PRINTED CIRCUIT BOARD TRANSISTOR CODE PRACTICE KIT: Complete Kit with PRINTED CIRCUIT BOARD; I Volume Control; 2 .01 Relay, chassis and 1 G.E. 2N107 Transistor; 3 Resistors; CDS photocell tube. Signa mfd Condensers; I Telegraph Key; I Dynamic Ear Phone; -all parts an listed in POPULAR ELECTRONICS. Net "rtes. KT- 49...... KT -53 Net 13 95 TRANSISTOR KITS Write For Brochure on ®w.n for 7 Cn.aloil IN POPULAR ELECTRONICS Q q IAON%,N.Y.¡542EFordM mt DESCRIBED as NEYIARK,N_I. 2 4Cl4lnlAve. COMPLETE PARTS including AMPREX GEIGER TUBE FOR 01511 I.F: COUNTER Iescrib 100 SIXTH AVE. KAINFIEti1,11.2 l3iiesttodSt. Net 27.95 KT -55 KIT NEW YORK. N.Y. 10STONMASS. ÏIOFedpaISt. COMPLETE ADDITIONAL. PART FOR DELUXE Ne l postage with order. KT-56 16.25 Include

August, 1955

AmericanRadioHistory.Com 241 4., 4114,-,',10, +hL ;' i' '}' Ki+44,1*7 <,3'-;f>.i

FIND to URANIUM REWARDS EASIER with achieve them is by means of alligator clips as shown in the photo. Using a pair The Only COMPLETELY of long -nose pliers, spread the sleeve of a clip so that the phone tip can be pushed TRANSISTORIZED into the sleeve securely. If the sleeve has been enlarged correctly, the tip can be MIRACLE GEIGER COUNTERS* Sensitivity: Indicates full stale on background count Completely transistorized power supply` NO TORALMOST NO TUBES INDESTRUCTIBLE o NO REPAIRS WEATHERPROOF

MIRACLE TRANSISTORIZED AUDIO -available separately at 515. -adapts to ALL geiger counters Amplifies detection clicks 10 times. Single 15c flashlight cell. 12 ounces. Size of cigarette pack cubed. Re- places guilty, irritating earphones. No drain on expensive geiger bat- easily pulled teries-pays for itself in short time! out when desired. Removing the screws on the clips may be necessary to prevent interference with the inserted (with scabbard). tips. 40" x 2" overall. Weighs less than 3 lbs. Over 1,000 hours continuous use on 2 -15e flashlight cells! Includes Universal's Transistorized Audio' & flashing neon light. Aluminum shield for beta discrimination. Disc and Tape Review

Gun Type $UAC 411: S149.50 (Continued from page 78)

(south holster). ably a "boo -boo" Neighs less than 4 lbs. Over 500 in the transfer from tape hours of continuous use on 2 -15e flashlight cells! to disc). Includes Universal's Transistorized Audio' built= It may in, and newly designed full view, free surprise many that I place the ratemeter swing wth 3 ranges. Aluminum shield for, great Toscanini in beta the third spot, but that's particle discrimination. all I can truthfully say his 'reading UNCONDITIONALLY GUARANTEED merits. All Don't get me wrong! instruments sold by UAC are tested and approved The Maestro couldn't by our scientific laboratory. Send your check do a bad job on order or money this work. But his furious (we pay shipping) or send 25% (we ship FOB N.Y.C. COD. energy seems, in this ). Specify single or double jack if order- case, misdirected. ing audio separately. Write for free information There may be many who uranium on say they like the prospecting and instruments from $19.95 breakneck to $4995. tempo at which the Maestro con- 'pat, applied for ducts this work. I, for one, do not feel that UNIVERSAL ATOMICS CORPORATION this is a wholly accurate representation Dept. E 8 19 East 48th of St. New York 17, N. Y. the work. And tempo is not the only fault the the dynamics are overblown and his LEARN practical handling of the orchestral choirs leaves Assemble a TRANSVISION much to be desired. 1V KIT In easy stagee.Pay as Soundwise, this is a Yoe wire-only Sts for Starting Package #1. Learn while building fair effort, but suffers a superb 17- to 2r screen TV Set with from the afflictions of latest features. Ideal for Fringe keas, adaptable to UHF. poor acoustics and Easy - no Instruments or technical restricted range . . . knowledge required. Free dtdog de. something the unfortunate scribes 8 great TRANSVISION IV KITS. Toscanini has Write today to Educational Dept. at- had to contend with, almost up TRANSVISION, to the close INC., Dept. PE, NEW ROCHELLE, N. Y. of his illustrious career. When one hears some of his very last recordings in which the new " Orthophonic" technique is uti- INVENTORS lized, one realizes how poorly this great When you are satisfied that you have invented value a matter of conductor has been served in matters -write me, without obligation, for full information on of what steps you should take sound in past years. If you were to secure a Patent. fortunate one of the 1 PATRICK D. HEAVERS who heard the Toscanini of 10, 15, or even 20 years ago, you will realize Registered Patent Attorney that 1098 Columbian his reading of this work then is Building Washington 1. D. C. most closely paralleled today by the Dorati ver- TRANSISTOR Personal Portable Radio Kit sion. BATTERIES LAST 10,000 HOURS COMPLETE . . . Nothing else to buy Fourth and fifth place SIMPLIFIED . A chiltl n assemble it honors are fairly Screwdriver only tools needed evenly divided TRANSISTOR, o batteries, tuning between the Krips /London attractive c arrying c ase, etc., struction. Completelee itennaain- Symphony disc and the Beecham /Columbia TRANSISTOR code practice oscillator kit recording. Beecham FREE with each TRANSISTOR radio takes a middle- of -the- only $9.85-check or money order. road approach to 10 -day Money -Back Guarantee the score; and if his read- RANS- AIREDepL `CTRONICNeW ing is not inspired, is 149 Broadway it at least competent. York O, N. Y. Krips indulges in many mannerisms and 112 POPULAR ELECTRONICS

AmericanRadioHistory.Com departures from the accepted norm, a fact which is surprising considering the good LEKTRON SPECIALTIES work this conductoi has done with the classic repertoire in the past. Krips out- ONE BUCK BUYS! guns Sir Thomas in matters of sound, al- have put though the Columbia engineers 10 PANEL SWITCHES foot forward." The London their "best KIT Selected shop assortment of most sound has cleaner, wider range in frequency popular toggle, bat handle, mo- OF THE mentary contact, se nsitiv string tone is less up to and dynamics, and the MONTH! switches, 8 types. Rated effort. 25 A. Variety contact arrange- "edgy" than the Columbia ments. Wt. 1 lb. Reg. $11. up . . . Dorati wins the potted Summing KIT. Brand if you 50 CERAMIC CONDENSERS. TV ACCESSORY de- palm, but ,you need not be ashamed disc, button new! 1 each 60 & 70 Scoop! Tubular. gree yokes, foc: ., coil. versions. types. 20 selected values. lbs. Reg. $10. j own the Leinsdorf or Toscanini 2 to 3000 mmf. Shop Wt. 8 1 lb. Reg. 513. CHASSIS, 5, 6 & 7 must! Wt. 10 RADIO chassis. 0 0 0 15 SWITCHES. Rotary. push, tube punch ed toggle. Expert- Workshop must! W C Symphony micro. lbs. 8 lbs. Reg. $8.50. The Fifth or "Reformation" menters, note! Wt. 3 Rare few Reg. $12. 60 MICA CAPACITORS. type, has been growing in popularity the past RESISTORS. 40 bargain! Postage stamp 125 CARBON ohms to .000l to .01 mf. Many the universal selected values, 100 silver. 5% too! 20 values. has not enjoyed 1 ;neg.; 1 1/2, 1 & 2 w. years, but /3. 1 lb. Reg. $17. On LP, Many 5% too! Top mak. Wt. recognition afforded the Fourth. ers-a rare buy! Wt. I lb. 75 KNOBS. TV and radio. Reg. $21. Some worth 250 ea. 15 $lt of the work, types, push-on. set screw. there are but five recordings 60 TUBULAR CONDENSERS. Reg. to 1 mf. up to Wt. 2 lbs. $8.50. the grade .00035 2 and of these only two can make 1600V. 25 types. Wt. 1 50 PILOT LITE SOCKETS. lbs. Reg. $10. Screw and bayonet bases. i Reg. $6. $1 as hi-fi recordings. 25 OIL CAPACITORS. Bathtub Wt. 2 lbs. and tubular. .1 to 2 mf. THREE LBS. HARDWARE. As- By great good fortune, the best perform- up to 600V. Well -known sorted. Over 2000 Pieces; and is on the mfrs. Wt. 4 lbs. Reg. $17. screws. nuts, lugs. etc. 1 ance is again by Mitropoulos, 10 881 Tubular Reg. $6.50. reviewed and EEP 1000 mf. R/C ASSEMBLY. Exclusive! other side of the Third Symphony Mtd. on term. strips: 70 tip le sections. Wt y2t lbs. $1 moulded, paper and mica ca- making this disc one of the best Reg. $11. pacitors, .0001 to .047 mt.. previously- 400V; 451/a watt resistors, To the Fifth, 60 mego. 1/2 to 1" long. t buys in the entire catalog. 20 and 2hwatts. leads Reg. i Many 5 %. Brand new. .2 lbs. 35 values. Reg. brings a stately grandeur, and Insulated. Wt. 1 lb. $15. Mitropoulos $1 RESISTORS. $15. ypes. once again he is blessed with exceptional 1500 PIECES SPAGHETTI aácandohm m' 50t tubing. lengths to 4 ". 5 to 10000 ohms, 5 to horns are particularly sizes. Reg. $7. $1 as. 15 values. Wt. 2 engineering. French Asstd. lbs. Reg. $11. $1 25 -ft. ROLLS WIRE. Plas- on this disc, and string TEN solid 15 CONTROLS. Up to 1 me g. well reproduced tic & cloth insulated: 12 se- 2 stranded. 3118 to 24, Some /switch. val- tone is a smooth and edgeless delight. asstd. colors. Wt. 2 lbs. i Reg. $5.50. ues. Wt. 2 lbs. Reg $12. is less incandes- POSTS & STRIPS. The Toscanini reading 50 RF COILS CHOKES 70 TERM. bind-. slug coils for TV, Builders' special! Asst. Fourth, but never- -tuned types. Wt. Ina pasts, screw & lug type cent in this than in the radio, lab. 20 1 strips (1 to 10 1 Ib. Reg. $15. terminal with his terms.). Wt. 1 lb. Reg. i theless is still too much imbued 10 BATHTUB OILS. Long- $4.50. lasting bathtub capacitors, .05 as "definitive." to 600VDC. Se- 10 PRECISION WW RESIS- nervous energy to qualify to 2 mf, m 1 & lected values. Some orth TORS. 10 different fairness lab t values. IRC WW 2. 4 & 2 it must be stated in all $3.50 each. Wonderful 1/2 However, assortment! Wt. 3 lbs. i 1/ & 1 watt. Wt. i how to delineate Reg. $25. lb. A $25 value! that the Maestro knows Erie & El- 25 TUBE SOCKETS. Up to a 25 VARIABLES. trim- do, and if it is letter - w /shield base, some mene° mica and ceramic a score as few others pin, some Handy mers. Singles d duals ceramic. 10 types. to a 8.30mf. you want, this disc has for shop. Wt. 1 lb. Reg. from 3-12 perfect conducting 58.50. Wt. 1 lb. Reg. $16. sizes & 50 MOULDED CAPACITORS. it to spare. 200 COIL FORMS. 50 All best known makes! Bakelite up to i 0 0 0 Exprimenters' $1 .0005 to 05mf raamie. 600V. Wt. 1/2 Ib. Reg. $13. I see that we have completed the Men - must! Wt. 2 lbs. Reg. $14. month, delssohn symphony round -up. Next BUYLINES! of the Mendels- SUMMER CLEARANCE we will take up the matter strap mid. ¡leg. $3.50..458 ea.; 3 for $1 2 H @ 200ma choke; for $1 concerto, as well as some piano Q 15mal 8.3 0.6A 656 es.; 2 sohn violin XFMR. In /115; Out/180V 8 for $1 assembly, enclosed, amber. Reg. 85e ea. works and other compositions. Pilot lite 12 for $1 trimmers, 3.12, 7 -45, or 8 -50. Reg. 970 ea. Any Erie Reg. $3 690 Darkroom or parts tray- 9x11x11/s. Wt. 5 lbs. Hi -Fi Record of the Month Sealed relay, 24VDC/300 ohms. DPDT. 2l/2x11/2x1trh. 51.49 Reg. $11 49 This month a classical record and a "pop" Veeter -Rout counter 0. 9,999. Reg. $6.50 $1 if 25 slug -tuned coils, asstd. TV- radio. Reg. $9 share recording honors, even they min. timer, bell rings end of cycle. Reg. $4.50 disc 0 to 20 $3 51 win- measures O to IOVDC. Reg. $8 are unwilling bedfellows! The classical 3" sq. meter, for $1 Full -wave rect./ 18 VAV to 12VDC W 250ma. Reg. $4..3 Liszt's Reg. for $1 ner is a 10" LP of that old warhorse, Dual variable. 15 mmf per sec. w /2" drum. $1...4 4 push control.3 for 91 Hungarian Rhapsody #2, with Albert Wolff Mobile, slug -tuned assem., broadcast band, Anti- capacity or lever switch CTS). 4P4T Orches- Any two for $1 conducting the Paris Conservatory 50 or 60 degree yokes win- Flyback transformer. Reg. $5 3r.$1 tra on London LD9171; and the "pop" RCA type 211T5 825 115/1/60 to 6V g 6 amps. Reg. $4 George Wright Reg. $ó í5o0 ner is a 12" LP entitled 500mmf Q 10 KV ceramic cartwheel condenser. 51 Plays the Mighty Wurlitzer. type standard bulbs. Reg. 100 ea..25 for 6 or 12 volt bayonet $1 0 0 0 Record changer bases. Reg. $4 buy C.O D. The Albert Wolff record is a terrific Please send check or M.O. Include postage. 30. at the low price of $2.50. I will positively orders 25% down payment. Rated accounts NET guarantee that this little disc will make sound Lektron Specialties, Dept. ES even the most modest of hi -fi systems Chelsea, Mass. 28 Gardiner Street CHelsea 3-6325 to the tremen- BULLETIN big and imposing ... due WRITE FOR OUR BATEST BARGAINFILLED dous sonorities generated by the orchestra 113 August, 1955

AmericanRadioHistory.Com I}txd!hMll 100M-41 1..kfHltl.f 100!1" BE 1P4FTT+,A;wIgerlitrP1 ..

in the opening and ensuing passages. Here is great, IT'S NEW! IT'S FREE! "big hall" sound, ultra - natural in its perfect balance. The contra- 1955 Walter Ashe Catalog bass here sound out hugely, yet they are of Radio, not "fuzzy." When the contrabassi and Electronics and TV trombone team up with the rest of the usual string complement and a big bass drum The Treasure in the introduction, the effect is tremendous. Chest of Values! The bass drum is stroked rather lightly in this passage Features all the leading brands and affords an inter- of Communication Equipment, esting test. Played on a small speaker sys- Test Instruments, Build -it- Yourself tem, it is almost Kits, Hi impossible to hear. Go up -fi, Sound and Recording a few notches Equipment, Radio,Electronics and in quality, and it begins to TV Parts and Supplies for every make its presence conceivable felt with the rest of the need . . in stock orchestration. -ready for immediate delivery. Play it on some real heavy- A "must" for experimenters, weight systems, ama- like the Jim Lansing "Harts - teurs, servicemen, engineers, field," builders and "hi- fiers." the Jensen "Imperial" or an Electro- Voice "Georgian," and its 30 -odd cycle solid impact lends solid substance to the orchestration which, in turn, has become still more sonorous. Send for Throughout the your RADIO work, the sound is very FREE Copy CO. wide-range in frequency and in dynamics, 1125 PINE Si. ST. LOUIS 1, MO. and distortion is virtually T MAIL COUPON non -existent. Per- TODAY! formance is slow paced, built WALTER ASHE RADIO CO. PE-8-55 on a grandiose 1125 scale. Some Pine St., St. Louis 1, Mo. critics have lambasted it being "draggy." for Rush FREE Copy of New 1955 Catalog. Let's face it the sic is ... mu- Nome slightly cornball, and if Mr. Wolff chooses to exploit Address its tonal nuances as an exercise in sonorities, I say . . . City Zone State good for him! I have heard enough "straight" performances of the work to last me I cannot a lifetime. recommend this disc too highly as I NEW RCA SURPLUS a demonstration piece, be your TV CAMERA weak system a -lunged 8" or a leather -bellowed ex- only $197.50! ponential horn. Labs, hobbyieta, Industries, TV technicians -net up your own telecast system! It's a "mechanical eye" for 0 0 0 factories, prisons, swim pools, closed circuit TV -100's Much other uses! SEND FOR FULL DETAILS TODAY! the same might be said about the FREE CATALOGUE ON REQUEST! ^------, "pop" winner, although HARJO SALES CO., Dept. it will be the boys 503 N. Victory Blvd. PE with I Burbank, Calif. the "big horns" who will derive the maximum benefit from this disc. George Wright Plays the Mighty Wurlitzer, on a new label called "HifiRecord," is a 12" LP Prospecting made easy with Gaidak's new tagged at $4.95, list. You $ will probably have U -238C triple -action gelge, counter! Also -.4, trouble finding this disc; so famous line of metal if you are in- locators, from 949.50 terested, drop me a card Send 25e for radioactive uranium sample! and I will prob- FREE ably know of a DETAILS. Dealer Inquiries Welcome, number of sources by the time this column appears in print. GOLDAK COMPANY 1547 W. Glensaks Blvd., Glendale, Calif.:: This is one of the most sensational pop organ recordings I have ever heard. George Wright was formerly organist at the New York Paramount theatre, and to put it WANTED mildly... he really knows his onions! A lot of the pop organ stuff I have heard has Old cylinder and been pretty awful, both from the stand- disc phonographs points of sound and performability. This Write full disc is as extraordinary description with outside horns. for the wondrous facility and technique of Mr. Wright as it and condition is for to the fabulous sound. POPULAR ELECTRONICS In such familiar old standbys as Jeal- BOX 50 ousy, Brazil, Stella by Starlight, Ebbtide, 366 Madison Avenue etc., Mr. Wright displays amazing virtuos- N. Y. 17, N. Y. ity. His choice of stops makes for interesting arrangements and tonal textures, yet he 114 POPULAR ELECTRONICS

AmericanRadioHistory.Com !t1PTl1A"*!'.! -aa..:ayt=g :ra yPp!P Fi.l,

it is a combining of a does not fall into the pitfall of gaudy over - band" jazz. Actually, previous 10" disc, which was quite success- orchestration as do so many of his contem- are used in the recording is ful, with some newer material. Heard poraries. The organ Perfidia, Tenderly, Your one of the biggest of that dying breed, the numbers like such, it has Drivin' Me Crazy, etc. Wurlitzer theatre type. As jazz mix, and 64 -foot pedals, As an example of a multi -mike some, gargantuan 32- to beat. The brasses and the engineers on this disc have cap- this would be hard bright sound .. . tured their full- throated power better than have that close -to, sharp, the saxes are richly mellow, yet have good I have ever heard before. for it. give you woofers a transient attack in sections calling Boy, these will really and big -throated. workout! In Jealousy, for instance, Mr. Trombones are growlly as rhythmic coun- Percussion is ultra sharp, superbly Wright uses the pedals wrapped in sound of and they give forth in your speak- clean. The whole is terpoint, wide range in frequency and er with a mighty WHUMP! The high end extraordinary and what is heard dynamics, balance is near perfect, acoustics is not neglected either, intimacy. To top comes through clearly with fine intonation. "live" without destroying amplifier and a it off, the surfaces are dead quiet and the As played through a 50 -watt sound is horn at a good loud level, net result of this and the splendid big exponential to the perfection of tape. the effect is such that neighbors begin to a near approach wonder how you managed to cram a theatre 0 0 0 organ into your home. and Mr. Wright do as Speaking of tape, especially prerecorded If the engineers worthwhile well in their next recording as in this, tape, we don't have anything worrying about their enough for review this month. However, I they'll have to start Tape tax bracket. Don't miss this one! have just been informed that the A/V Libraries are now issuing tapes taken from o o 0 the masters of that excellent small company, Vanguard. I understand both their BIG BAND BASH will be available, May and his Orchestra classical and jazz releases Billy some new riches to T -329, 12" LP, RIAA curve, $3.98 which should give us Capitol you posted and see you This 12" disc is a must for those of you review. I'll keep who like smooth, slickly orchestrated "big next month. -

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AmericanRadioHistory.Com Carl & Jerry (Continued from page 67) Now, the newest, finest Radio -Control Garage hams had been using on 10 and 20 meters for Door Opener styled in a years. modern spun -aluminum To change a folded dipole into a yagi, fixture that beautifies you mount the dipole horizontally garage interiors. on a long horizontal boom. On this boom, parallel to Convenience and safety the features galore New dipole, you mount several other metal automatic - shut -off, posi- rods or tubes called 'parasitic elements' be- tive locking of door, cause FCC authorized ra- they have no direct connection to dio the frequency - 'driven element' that is and many more ells I connected to the qualities! feedline. Parasitic elements on the front PRICED part of the boom are Write today called 'directors,' and for de- n ] J they are a trifle scriptive literature. shorter than the driven _ element and mode must be mounted at certain better! critical distances ahead of * It's really simple to install that element. At , the rear of the EverYoneco" one man can do it boom, also at a critical dis- easily! tance, is afford * Takes just an afternoon with mounted a parasitic element called this modern common hand tools; no soldering. a 'reflector' that is somewhat longer than conveniencet * Complete instructions assure the driven element. professional- type installation. "A complete yagi may have all the way from 3 to 12 or more elements. Directors S I 4727 concentrate the received .rr COM PANY N, DAMEN AVE. I signal on the driven j CHICAGO 25. ILL. element in much the same way Please send that lenses FREE descriptive literature on your focus light. The GARAGE DOOR reflector reinforces this I OPENER Please advise name of your nearest action in the same manner distributor electronic parts I that a polished carrying your GARAGE DOOR OPENER surface will reflect and concentrate I NAME rays light on a particular spot. The end result is I ADDRESS that the reception of CITY a signal arriving from STATE the front of the antenna is greatly improved _I and response to a signal arriving from any point of the compass except the front is cut PRINTED CIRCUIT MATERIAL way down." "Sounds like the perfect answer to Copper Laminated Bakelite 1/16" thick, antenna the TV coated on one problem." side. Ideal for making your "For single -channel own PC receivers. Sheet size 4% x 6. Special reception, it's hard offer, limited time only, to beat -but there's the rub. In its conven- 2 Sheets, postage paid $1.00. tional form, a yagi is a very narrow -band affair good Lorenz "61" kit, with conventiónal base and for reception only of the single 3 copper laminated bases to provide practice channel for which it is designed. however, Lately, material. Complete except for tube and relay the engineers have given the old $3.95. yagi a new look by working it over into what Larger sizes copper laminate 3c per square inch. ACE RADIO CONTROL BOX 301 HIGGINSVILLE, MO.

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AmericanRadioHistory.Com is known as the broadband yagi -capable of yielding good signal strength and excellent basicelectricit front -to -back ratio on all 12 v.h.f. channels. LEARN This is done by using more than one driven electro ics element and by carefully adjusting the THE EASY "PICTURE BOOK" WAY! length and spacing of the parasitic elements Just Released: The fabulous so that they do double or triple duty, proof ducing effectively the equivalent several Training Course different yagi antennas mounted on a single ILLUSTRATED boom. That antenna over there, next to the now used by the U. S. Navy! church, which is called an 'Interceptor,' is a good example of this design." You Learn by Pictures elements Over 25,000 Navy trainees have already learned Basic "How about those jobs with the Electricity and Basic Electronics this easy, "Picture sticking out every which way? I think they Book" way! Now, for the first time, YOU can master called conicals." the basics of Electricity and Electronics with this are sante "Learn -by- Pictures" training course! Over 1.700 "Well, going back to our original dipole, simple, easy -to- understand drawings explain every increasing the physical size of the dipole section -these "teaching" pictures actually make up more than half the entire course! No other Basic elements will widen the frequency response. Electricity or Basic Electronics course in America Theoretically, the best way to do this is to uses this revolutionary illustrative technique! You use metal cones mounted tip -to -tip for the learn faster and easier than you'd dream possible! flattened into A Complete Idea on Every Page elements. The cones can be Here's how this easy, illustrated course works: every triangular sheets of metal without much page covers one complete idea! There's at least one loss of effectiveness, and this is actually big illustration on that sante page to explain it What's more, an Imaginary instructor stands figura- done on the u.h.f. channels. The resulting tively at your elbow, doing "demonstrations" that dipoles are called 'bow-ties' because of their make it even easier for you to understand. Then, at the end of every section, you'll find review pages that appearance, and are usually mounted in highlight the important topics you've just covered. front of a reflecting metal grid or inside the You build a thorough, step -by -step knowledge at your jaws of two such grids edge- connected at a own pace -as last as you yourself watt to go! English- -A Course Anyone Can Understand 90° to form what is known as a 'corner Everyday angle Sponsored by the Navy to turn out trained techni- reflector.' cians in record time, this modern course presents "On the v.h.f. channels, where wave- Basic Electricity and Basic Electronics in a simple way that everyone can grasp -regardless of previous lengths are measured in feet instead of education! Every phase is made instantly clear -ex- inches, a bow -tie of proper dimensions would plained in plain, down to earth English-with hun- be too bulky and expensive and have too dreds of easy -to- understand illustrations to help you! wind resistance. However, metal rods 10 Complete Volumes much Volumes I and 2 of "Basic Electricity" cover DC or tubes that preserve the outline of the components and circuits; Volumes 3 and 4 cover AC bow -tie, and that might be considered the components and circuits; Volume 5 covers AC and of the original cones, serve almost DC motors and machinery. skeleton Volume 1 of "Basic Electronics" covers Diodes & as well. By inclining the skeleton wings of Power Supples; Vols. 2 and 3 cover Amplifiers & 'conical' dipole slightly forward to form Oscillators; Vols. 4 and 5 cover Transmitters & this Receivers. a shallow funnel, reception on the higher Home Study Without Correspondence channels is improved. TV signals are direct- This course is so different, so complete- there's no need for the usual letter writing, question and answer ed in toward the feedline point in much the correspondence! Learn at home -at your own pace! 10 Day Examination- -Money Back Guarantee Send today for these exciting new training courses- you risk nothing! When you receive the volumes, examine them in your own home for IO full days. 1f, at the end of that time, you're not completely satisfied, simply return the books to us and we'll gladly refund your full purchase price! Total cost for either 5-volume course is only $9.00! In Canada, prices approximately 5% higher. ORDER TODAY! These books are sold by electronics parts jobbers and book stores. 'If YOUR dealer doesn't have these books, mail this coupon to us! MD JOHN F. RIDER PUBLISHER, INC. 480 Canal Street, N.Y.C. I have enclosed $ Please send me 5 -voL Basic Electricity set @ $9 set 5 -voL Basic Electronics set @ $9 set Both sets. I understand I may return the books in 10 days, and receive a complete refund of the full purchase price if I am not satisfied. Add state or city sales tax where applicable. Name Address "It's going to be something a little L City State bit different in R /C1" & ------==J

August, 1955 117

AmericanRadioHistory.Com ELECTRONIC SUPPLIES same way that sound waves are collected by an old- fashioned hearing trumpet. A For Experimenters- skele- Service -Industry ton bow -tie reflector is usually mounted be- Guaranteedabassis .teWHOLESALEaOR RETAIL. hind the conical antenna to improve the PORTABLE V I BR A P A C K- , Crystal Diode IN34 -New- front -to -back ratio. To get still more Transceivers, Walkte, Talkies, 2/51.00 etc. Operates from 12V source Miniature xformer strength in fringe -SOC outputs- complete ith tern-Cis-Maio -9 porcel areas, it is a common schematics, plug, spare vibra- on case....90f tor. etc. Govt. cost over Headbands for earphones - practice to stack two, four, or even more of Ship wt. $100- boxed 2 for $1.00 10 Ibs.Speeial 54.95 Cushions for earphones. these conical 'bays,' as they are called, MODEL OAV-1 RADAR TRAIN.. 4 for $1.00 one MO UNIT -115 Volt 80 Cycle SM Chassis- contains val parts above the other on -Variable freouency outputs -800 ohm plate relay. .$1.00 the same mast, and con- 150.250 MC -Fixed Outputs. Miniature torage btry-2.2 nect them to a common feedline. 1KC; 3KC; 10KC; 100KC. Volts - 2xt/yxt /2 - New. Dry To insure Housed in beautiful grey cabi- charged 980 that the signals net. Shipping wt. 70 lbs. Battery tester -King Sol -Foto picked up by the several Govt. cost over $ 500- Special, Flash Fans Save Film. Time bays Complete with all tubes -in- Closeout 980- actually reinforce instead of buck each struction book $14.95 Mica window Geiger Muller ELECTRONIC tube-Type CT-BS-8-540 reg. other, it's necessary that bays be mounted Remote Control star price...... Special $7.95 4. Chassis -loaded with valuable W.E. the proper parts, plate relay xformer etc. Ouncer Xformer Ratio distance apart and that they be 4 for $3.00 2.5.1 2 for $2.00 Sub-miniature hearing a id connected together with special 'stacking WESTERN ELECTRIC STEP- tubes, unbranded 5 for $1.00 PER SWITCH -6 or 12 VDC.- Miras, Silver Micas Asstd -Big harness.' " 44 steps -Bridging wipers- Value ...... 75 for $1.00 Cold Plate Contacts -4.4 Ohms 3A5 UHF twin triode.3 /$1.00 "Any more TV -1 make -1 lmeak.NEW $7.95 Generator 3450 RPM -Output antennas ?" Carl asked Test Set U5 /O Nancy Re- 425VDC -78.5 Watts... $5.00 drowsily. ceiver Housed in Beautiful Paper tubular cond. Oak Chest. Contains BO, 2 50 for $1.00 conductor Microphone cable SPST Toggle ,w 4 for $1.0o "Lots more, but you'd never stay awake Probes, Plugs, Etc. Govt. cost- CoAx fitting Chassis - over $100.. Brand new $4.95 SO -239 2/900 to hear about them," Jerry observed tartly. male -PL- - Small Parts & Tube Values Moved 3/51.00/53.00 "Some antenna manufacturers Crystal Diode IN22 -New- Rew -1 Recar -200 MC- depend upon 3/51.00 INew w /tubes $3.50 stacking several dipole- and -reflector Altitude bays Calculator -5 Circular slide rule ype chart, In leather vertically folio 12x12 -Br. New -Govt. Cost $20 Special for increased gain. Half -wave ele- $1.00 ments, 2050 Thyratron properly phased, may be mounted 1.25 954 acorn 3/1.00 1625B.pentode 3 /1.00 2D21 Thyratron 1.00 955 acorn 2/1.00 1626 triode 4 /1.00 side by side and several such bays stacked 884 Thyratron 1.25 956 acorn .75 1629 magic eye 4/1.00 VR105 Volt. Reg. .95 957 acorn .75 838 triode 1.50 to form what is called a 'collinear array.' VRI50 Volt. Reg. .95 958A acorn .75 902 -2' C. R. Tube 5.00 959 acorn 1.75 The appearance of such an antenna, together with a reflecting screen, has Include Postage With Order given rise to its popular nickname of 'the bedspring anten- REX RADIO SUPPLY na.' Other manufacturers combine yagi and 88 CORTLANDT ST., NEW YORK 7, N. Y. conical antennas on a single boom, hoping to get the benefits of both from this marriage." "What's meant by antenna gain ?" GEIGER COUNTER "That's the ratio between the signal volt- KIT age delivered by the antenna to the feedline You can assemble it yourself in on a certain about an hour. All holes drilled channel and the voltage deliv- and ready for wiring. No special ered by a reference dipole antenna to tools required. Full instructions cut the and easy to follow diagram in- frequency of that channel and mounted in cluded. Government booklet the same spot. This "Prospecting with a Counter" and ratio is expressed in radioactive sample provided free decibels. For example, if the antenna under with kit. Full price including tubes, headset and batteries only test delivers twice as much signal voltage as $17.50 postpd. Satisfaction Guar- does the dipole on Channel 6, anteed. Order your kit today. we say it has STOWERS a 6-db gain on that channel. & SON, Dept. 51, 804 Grand, Kansas City G, Mo. If it delivers four times the voltage, it has a 12 -db gain." "What characteristics would you say the TRANSISTOR RADIO!!! perfect TV antenna should have ?" World's smallest and lowest priced transistor set. Perfect for baseball fans, office workers, "First, it should have high gain; second, it children. Polystyrene plastic case smaller should maintain this gain than cigarette pack, carry in shirt pocket or across all v.h.f. purse. Tunes all stations. Operates one and u.h.f, channels with no peaks month on two pen cells. Plays indoors, out- or dips; doors, at beach, on boats. Ideal third, it should present a consistent 300 -ohm emergency portable for Civil De- fense stations. Assemble quickly. impedance to the feedline on all frequencies; Complete with battery, less earset - fourth, it should have $12.00. Special Imported hearing aid ear - a single, narrow re- set- $4.00. Single headphone -$2.00. Post- ception lobe and should paid. Cash, Check or Money Order. East- present infinite re- ern Audio Research, Box 62, Little Neck jection to signals arriving 63, New York. from the side or rear; and finally, it should be cheap, light, and easily mounted, with a low wind resistance and a beautiful appearance." Get your FCC LICENSE quickly! "Sounds like quite an order." Guaranteed preparation, in a MINIMUM OF TIME, "It is, especially when you realize for F.C.C. commercial operator examinations. Our that highly specialized training is available by correspond- antenna gain, bandwidth, front -to -back ra- mice, or in resident classes in tio, and WASHINGTON, D. C. and HOLLYWOOD, CALIF. impedance are all closely inter- Write for our free booklet with complete details. locked so that you cannot vary one of them Grantham School of Electronics, Dept. 104 -P without changing all the others. And right 737 11th Street N.W., Washington 1, D. C. there you have your answer as to why there 1 POPULAR ELECTRONICS

AmericanRadioHistory.Com are so many different kinds of antennas. Each manufacturer tries a different com- promise in his approach to this ideal antenna. One may stress high maximum gain or front -to back ratio; another advertises NOWTOEIXINY price and appearance; still another may boast that the response curve of his antenna has no sharp dips and valleys in it -something especially important in an antenna used for color TV reception. Each advertis- PMTOfAIYCAR C ing claim appeals to a certain group of cus- tomers who feel that the stressed character- Q CRLY - -FAS /L Y - -R/G HT, is just what they need to solve their l// istic STEERING GEAR reception troubles. If it doesn't, then they IGNITION are ready to try another new antenna, always hoping they will eventually come CARBURETOR REAR ENO across the perfect TV antenna which will OENlRAI OR insure perfect reception all the time." SHOCK "You sound a little cynical about this." ABSORBERS it UNIVERSAL "I'm not really. I know how important AUTOMATIC in a TRANSMISSION is to have a good antenna, especially WHEEL CLUTCH know for a fact ALIGNMENT weak -signal area; but I also VIII RIB UT OR that the TV antenna can only do so much. It cannot receive a signal that just isn't there; nor can it compensate, beyond a certain point, for a poor receiver. The TV an- RGORAR you're a beginner MOTOR'S tenna is like the automatic choke on a car; VV or an expert mechanic - it is now you can "breeze through" it gets a lot of blame for 'sins' of which any "flx-it" job from simple carburetor not guilty." stlooku up job in indecompleteof MOTOR'S AUTO rose and brushed the grass from the Brand -New 1955 Auto Repair Manual. Carl Follow simple step -by -step directions, seat of his pants. clear pictures. Presto -the job is done! REPAIR{ had better be starting No guesswork! MOTOR'S MANUAL "Well, I guess we takes you from "scratch" - shows Marconi. Do you think you will be WHERE to start. WHAT tools to MANUAL for home, use. Covers EVERY job on EVERY car to down the hill or had I better built from 1940 thru 1955! \. able totter Covers 737 Models just roll you like a barrel ?" Everything You Need to Know All These Makes from 160 Official "Don't get smart with me," Jerry said, as "Boiled Down" Buick Hudson Shop Manuals Cadillac Kaiser he struggled to his feet, trying not to wince ENLARGED, 1955 Lincoln NEW, REVISED, from over Chevrolet protest from his sore muscles. "Just Edition shop manuals i Chrysler Mercury at the 160 OFFICIAL essential air Nash fled for YOU. 23,436 Over Crosley don't get in my way.going down as you did specifications on 737 chassis models. De Soto Oldsmobile 1,000 big pages. More 00 pictures, 5,,ÖÓÓ a ,9íc0 Dodge Packard coming up." ..this-is-how' beginners every Plymouth and repair facts. Leads re- Ford step of the way. Time- saving factory Frazer Pontiac pair procedures for experts. Instructions Studebaker and pictures so clear youu 'A Henry.' wrong. Used by U. S. Army T co Willys 2,000,000 Copies Short -Wave Bands Book FREE 7 Days Sold! SEND NO MONEY! Pay postman nothing Make s (Continued from page 72) ou what it'ss got. Un- Same FREE Offer On MOTOR's less you agree this Manual is the greatest time Truck and Tractor Monrovia, has moved and on LIBERIA -ELWA, ver seen- returnbook Covers EVERY fob 15200 kc. This one is being EVERY popular make from 11800 to nothing.a Mati CouPpañ gasoline 1946 thru Bible" pro- today toi MOTOR, FREE 7 -Day heard daily with a "Back to the Book Dept.. Desk 328, 1954. box 2500W W. 5 th St.. New Trial. Check proper gram at 1250 -1330. Another religious pro- S. In coupon. gram starts at 1400. Their address is P.O. MAIL NOW FOR 7 -DAY FREE TRIAL Box 192, Monrovia, Liberia, and they ask COUPON Calif.) MOTOR BOOK DEPT. for reports. (Taylor, N.J.; Kenney, Desk 328, 250 W. 55th St., New York 19, N. Y. t you want): NETHERLANDS NEW GUINEA -The complete Rush to me at once (check box opposite book MOTOR'S New AUTO REPAIR MANUAL. If O.K., I will remit and a final payment of 95c Radio Omroep Niew Guinea, $2 In 7 days, $2 monthly for 2 months schedule from (plus that. emitd9 I will th(Foreign ice, rem, coshs follows : Sundays to Thurs- book postpaidsIno7 days Hollandia, is as with order.) 1930 -2030 on 7126 kc.; daily -0400- MOTOR' New TRUCK & TRACTOR REPAIR MANUAL. If days- O.K., I will remit $2 in 7 deys, and $2 monthly for 3 months, plus 36c delivery charges with final payment. Otherwise I will re- 0700 on 3345 and 5045 kc.; Friday -2200- price, remit flu cash turn book postpaid Is 7 days. (Foreign 0030 on 7126 kc.; and Sunday- 1830 -2330 on with order.) 250 rig 7126 kc. The transmitter is a -watt Print Neale Age made by Philips, with 200 watts fed into the antenna. All programs are in Dutch Address City Staate except at 0900 -0930 (daily except Sunday) charge coupon entire parvient 9 $6.`01 far Auto Repair Manual (or $ö is A new trans- f Some return- refund privilege. when Malay transmitting. far Truck & Tractor Repair Manual.) I mitter of 5000 watts is expected to be in 119 August, 1955

AmericanRadioHistory.Com 611p3!aux u gIP r.;eP'l;rSrNisnwlP .MN ..zsejg ..1 1Vl lil1- 1 ^ r - r t t

operation by October 1 from the Island of Biak; it will, of course, be s.w. (Schemer, TECHNICIANS N.J.) PERU - OAX8C, Radio Nacional, Iquitos, has moved to 9335 from 9523 and is being WANTED received much better due to less QRM. OAX4Z, Radio Nacional del Peru, Lima, RADIO TELEVISION AND ELEC- at TRONIC INDUSTRIES NEED is now using 6082 kc. at 1800 -0000. This WELL TRAINED MEN. replaces the old frequency of 9560. (Legge, The man who really has Va.) the "know -how" will win the PORTUGAL -Lisbon, on 9776 kc., has moved best rank and position and the to 15120 kc., and is being heard at 1230- highest pay in the years ahead. 1530 in Engineering Opportunities the African beam. shows how you can be thor- SARAWAK -Radio Sarawak is audible at oughly trained by specialized times on the West Coast at 1300 -1400 with home study courses. It lists English on the 5050A outlet. (Kenney, details of over ninety courses Calif.) in all branches of engineering TURKEY -TAT, Ankara, on 9515 kc., is noted and academic fields. Get your free copy of "Engineering Op- regularly at 1815 -1900 with news and pop- portunities" to -day by mailing ular American records. Announcements are the coupon below. in English. (Meyers, Ohio; Thomas, Pa.) LIBERIA (Additional) - The transmitter Canadian Institute of Science & Tech- being used by ELWA is a Gates, 10 -kw. nology Limited, 594 Century Building, 2 412, 5th Street, N. W.,Wash ington, D.C. rig, covering to 22 mc. Temporary anten- Please forward free of cost or obliga- na is a triangle matched half -wave unit. tion of any kind your 105 -page handbook, The permanent "ENGINEERING OPPORTUNITIES ". antenna will be a three -wire Name rhombic on a 240' stainless tower. (Finkle, Add ress Calif.)

Course interested in Age As WE MENTIONED EARLIER, sunspots affect radio reception; the greater the sunspot activity, the better s.w. reception will be. WALKIE- The latest sunspot prediction is as follows : TALKIE for August -18; for September -19, and Build a real wireless portable radiophone for the 2 meter amateur band with the following precision components. Factory wired and tasted for October-21. Compare this with an transceiver chassis o plete with special dual tuba $6.50. UTC "ounear" mike transformer á.98.c High output carbon mike $1.49. Super Alnico actual average of 11.3 for last April. Short- headphone Y' x 5" x 9" $1.25. aluminum case $2.00. Wiring diagram $ .50. wave reception should improve Uses standard batteries available at your local radio store. Please include consider- 5% for postage. COD's require $1.00 deposit. ably before the next DX season rolls SPRINGFIELD ENTERPRISES around. (Swiss S/W Service via Ferguson, Box 54 -E Springfield Garden 13. N. Y. N.C.) 30 When Answering Advertisements Audio Watt Please Be Sure to Mention (Continued from page 85) POPULAR ELECTRONICS watts at this 1000 -cycle frequency will be the square of the voltmeter reading di- BUILD DESIGNEDf ,-HOME CRAFTSMEN vided by the resistance of the resistor. The SOLOTRON mew EASY TO BUILD purpose of the oscilloscope is to observe 30 KEYS the output waveform for distortion. When , -...,.044,-:,:*-- 3 TUBES -2 WATTS the waveform begins to depart from a smooth sine wave, the amplifier output 9/re SOLOTRON Ca ao contains distortion which, as mentioned 29641 GILCHRISTAV earlier, must be considered along with the PLANS DEP'T.PE FARMINGTON, MICH. power output. The method of measuring audio power TV TUNER REPAIRS just described is well within the capability 48 -HOUR SERVICE of the audio hobbyist who has an audio Defective tuners rebuilt to factory standards. New tuner guarantee. Ship prepaid. oscillator and a vacuum -tube voltmeter RADIO PRODUCTS CO. sensitive enough to read the minute out- College Point 56 New York put of the oscillator as well as the ampli- We carry a full stock of fier voltage. Replacement Tuners for all makes of T.V. output For the hobbyist who desires to make his own wattmeter, a sim- 120 POPULAR ELECTRONICS

AmericanRadioHistory.Com plified design using a crystal element is shown in the Sylvania Electric Products Inc. booklet called "Forty Uses For Ger- WHAT SECRET POWER manium Diodes." The Heath unit shown POSSESS? in the photograph is sold as a kit for DID THIS MAN home construction. 30

CdS Photocell (Continued from page 43) technique was developed for mounting this lens and cell. The cell is wrapped with a few layers of tape so that it fits into the neck of a large rubber attachment plug, and the lens fits in the other end after the prongs have been removed. Both parts fit tightly and will stay without further fastening, but a drop of glue may be added if desired. The assembly is mounted to the chassis by means of a metal electrolytic capacitor mounting plate. A suitable lens for this device can be BENJAMIN FRANKLIN obtained from any of a number of surplus (A Rosicrucian) optical houses, such as Edmund Scientific Corp., Barrington, N. J. Quality is not im- WHY was this man great? How does anyone portant; a cheap lens will perform as satis- -man or woman -achieve greatness? Is it not factorily as a more expensive one, for its by mastery of the powers within ourselves? purpose is to concentrate incoming light. After the unit is assembled and the Know the mysterious world within you! At- switch turned on, the relay should close tune yourself to the wisdom of the ages ! Grasp when the lens is illuminated by a bright the inner power of your mind ! Learn the sec- light, and should open when the light is rets of a full and peaceful life! might be interrupted. The only adjustment Franklin many other learned to move the photocell back and forth in its Benjamin -like mounting to make sure that it is located at and great men and women -was a Rosicru- the focal point of the lens. This is the point cian. The Rosicrucians (NOT a religious or- of maximum sensitivity. One precaution: ganization) first came to America in 1694. make certain that the load placed on the Today, headquarters of the THIS BOOK relay contacts does not exceed the ratings Rosicrucians send over seven given by the relay manufacturer. FREE! million pieces of mail an- _ made at A suitable source of light can be nually to all parts of the MASTERY OF LIFT from a small automobile spotlight powered world. Write for YOUR by a filament transformer, or any other of "The Mas- narrdw beam. FREE COPY source giving a relatively No The relay can be hooked up to operate a tery of Life"-TODAY. light, bell, counter, or whatever the ex- obligation. No salesmen. A perimenter wishes. By proper choice of non -profit organization. Ad- relay contacts, the unit can be connected dress: Scribe N. P. K. to operate when the light beam is interrupted (normally closed contacts), or to operate when a beam of light strikes it 7 e ROSICRUCIANS (normally open contacts). In some cases, it SAN JOSE ( AMORC) CALIFORNIA might be desirable to shield the lens from r - -- --SEND THIS COUPON by means of a short tube having Scribe N. P. K. stray light The ROSICRUCIANS (AMORC) an inside diameter approximately the same San Jose, California as the lens diameter. Please send me the free book, The Mastery of Life, which explains how I may learn to use my facultee . Although somewhat lacking in sensitiv- and powers of mind. ity, this device will provide loads of fun for the experimenter. Future issues will Name describe units incorporating amplifiers for Address increased sensitivity, and will discuss some City other applications of this versatile photocell. 30 August, 1955 121

AmericanRadioHistory.Com Ama- Touring (Continued-from page 70) BOU of the OX3 calls formerly used. The first oc 9AÀ one on was KG1AA, heard on 14.20 at 0430 AT : 0'r' LIS TENT: R R-ì.PORT To Radio JANE AND ROOM 00- and 0600; he TO uses 300 watts and a rhombic mBO BORI BUMS ARM antenna. (Don Kenny, Calif.) 9 SCUM O WEST Europe TRISTAN D4 CUNIUI Yow Wont Jigs Andorra -A beam antenna is en route to R_S-T_on '+ mrs PX1YR, Andorra's only .sor iio cnrr ontltsss amateur, so he B.uxuMB

should be getting out better. TNX QSL Q,a( NM@ FM Liechtenstein -Swiss amateur HB1MX is operating portable in Liechtenstein on This rare QSL card is from the island in weekends. He operates around 14.15 mc. the South Atlantic Ocean called Tris- Rhodes -SVOWU should be on by now from tan Da Cunha. To obtain QSL cards Rhodes, according to a statement made by like this requires patience and a knowl- SVOWM. edge of where and when to listen. Asia and Oceania Brunei-VS5CT, 14.155 mc., was heard at 0800, including: KR6AF, 14.175; KR6LJ, 1100. He said he would be going to British 14.13; KR600, 14.145; and KR6USA, 14.125. North Borneo (VS4) soon, and that QSL's (RL) should be sent via the VS2 QSL Bureau. Africa (Jim. Moore, Calif.) Reunion Island -FR7ZA Caroline Islands- KC6CG, is being heard on located on the 14.115 at 0930. He uses phone island of Ulithi in the Eastern Carolines, only occa- sionally, as he generally operates on c.w. has been noted on 14.24 mc. at 0315. He also operates on the 21 -mc. band. (Moore) (Moore) Cook Islands- ZK1BI, Raratonga, was heard Seychelles- VQ4NZK plans to make on 14.18 mc. at 0320. His transmitter is 50 a trip watts. (Kenny) to the Seychelles and ollerate from there as VQ9NZK, but the date is still Formosa -BV1US has been noted on 14.20 unsettled. and 14.25 at 0920. C3VA was heard on The following are other Africans who are 14.205 at 0320. The address for BV1US is active on phone, arranged alphabetically MAAG, APO 63, c/o P.M., San Francisco, by call letters. Frequencies shown are sub- Calif. (Moore) ject to variation. Midway -KM6AX was logged on 14.21 mc. CN2 (Tangier) : CN2AD, 14.11 at 0330. (Kenny) CN8 (Morocco) : CN8GQ, 14.14; CN8MM, Netherlands New Guinea -JZODN was noted 14.17 on 14.195 mc. at 0325 with weak signals. CR4 (Cape Verde Islands) : CR4AG, 14.15; ( Moore) CR4AL, 14.12 Okinawa CR5 - Okinawa stations are getting (Sao Tome) : CR5NC, 14.19 through to the East Coast around 0600- CR6 (Angola) : CR6AG, 14.14; CR6BH, 14.17 CR7 (Mozambique) : CR7AU, 14.19; CR7CF, 14.11 CT3 (Madeira) : CT3AN, 14.15 EA8 (Canary Islands) : EA8AI, 14.18; EA8AP, 14.16

EA9 (Spanish Morocco) : EA9AR, 14.19; EA9BC, 14.15 EA9 (Rio de Oro) : EA9DE, 14.18; EA9DQ, 14.13

EA0 (Spanish Guinea) : EASbAB, 14.11; EAOAC, 14.19 EL (Liberia) : EL2X, 14.11; EL9A, 14.19 ET2 (Eritrea) : ET2US, 14.18; ET2ZZ, 14.12 ET3 (Ethiopia) : ET3Q, 14.32; ET3S, 14.17 FA (Algeria) : FA3GZ, 14.13; FA9WD, 14.19 FB8 (Madagascar) : FB8BC, 14.17; FB8BM, 14.19 Ham band listening post of Thomas FE8 (French Cameroons) : FE8AC, 14.12; Neal located at Mt. Rainier, Maryland. FE8AE, 14.15 122 POPULAR ELECTRONICS

AmericanRadioHistory.Com FF8 (French West Africa) : FF8AH, 14.11; FF8AP, 14.12 FL8 (French Somaliland) : FL8AI, 14.15 BUILD 15 RADIO KT1 (Tangier) : KT1UX, 14.17; KT1WX, 14.19 CIRCUITS AT HOME 095 (Belgian Congo) : OQ5CX, 14.16; OQ5FO, 14.19 With the New Improved 1955 ONLY OQQ (Ruanda-Urundi) : OQ0DZ, 14.19 Progressive Radio "EDU -KIT" ST (Sudan) : 14.14; ST2DB, ST2NW, NOW INCLUDES 14.17 RECEIVER, TRANSMITTER, V92 (Northern : VQ2DT, 14.14; Rhodesia) SIGNAL TRACER, VQ2FU, 14.18 CODE OSCILLATOR CIRCUITS V93 (Tanganyika) : VQ3ES, 14.15; VQ3RJB, 14.12 Attractively Gift Packaged Free Soldering Iron V94 (Kenya) : VQ4AQ, 14.14; VQ4EZ, Absolutely No Knowledge 14.18 of Radio Necessary No Additional Parts V95 (Uganda) : VQ5EK, 14.14; VQ5DES, Needed 14.17 Excellent Background For Television VQ6 (British Somaliland) : VQ6LQ, 14.15 30 -day Money -Back V98 (Mauritius) : VQ8AL, 14.11; VQ8AR, Guarantee 14.16 School Inquiries Invited Used in 79 Countries V98 (Chagos Islands) : VQ8CB, 14.10 Learn High Fidelity ZD2 (Nigeria) : ZD2EHW, 14.18; ZD2RWW, 14.19 WHAT THE PROGRESSIVE RADIO ZD3 (Gambia) : ZD3BFC, 14.11 "EDU -KIT" OFFERS YOU ZD4 (Gold Coast) : ZD4BF, 14.17; ZD4BR, You will learn how to identify Radio Symbols and Diagrams: how to build radios, using regular radio schematics; how to wire and 14.12 solder in a professional manner. You will learn proper chassis layout. You will learn the basic principles involved in radio ZD6 (Nyasaland) : ZD6BX, 14.10 reception, transmission and audio amplification. You will learn how to service and trouble -shoot radios. You will learn code. ZD8 (Ascension Island) : ZD8AA, 14.175 You will receive instructions for F.C.C. Novice license. In brief you will receive a practical basic in ZD9 : ZD9AB, 14.17; education Radio, worth many (Tristan Da Cunha) times the small price you pay. ZD9AC, 14.14 THE KIT FOR EVERYONE It is not necessary that you have even the slightest background ZE (Southern Rhodesia) : ZE2JN, 14.20; in science or radio. The "Edu -Kit" is used by young and old; by ZE6JI, 14.17 radio schools and clubs; by Armed Forces personnel and Veterans. No instructor is required. Instructions are complete, simple and ZS (South Africa) : ZS1SW, 14.19; clear. ZS5DE, 14.12 PROGRESSIVE TEACHING METHOD The "Edu -Kit" uses the principle of "Learn by Doing." ZS3 (Southwest Africa) : ZS3AH, 14.13; Therefore you will build radios, perform jobs, and conduct experi merits to illustrate the principles which you learn. You begin ZS3P, 14.16 by learning the function and theory of each of the radio parts. Then you build a simple radio. Gradually, in a progressive man- ZS7 : (Swaziland) ZS7A, 14.14; ZS7C, 14.17 ner, you will find yourself constructing more advanced multi -tube radio sets, ZS8 (Basutoland) : ZS8E, 14.15; ZS8I, 14.10 and doing work like a professional Radio Technician. The "Edu -Kit" Instruction Books are exceedingly clear in their Z59 (Bechuanaland) : ZS9F, 14.18; ZS9G, explanations, illustrations and diagrams. These sets operate on 105 -125 V. AC /DC. For use in foreign countries having 210-250 14.16 volt source, an adapter for 210-250 V. AC /DC is available. 3V8 (Tunisia) : 3V8AS, 14.195; 3V8BL, The Progressive Radio "EDU -KIT" is Complete You will receive every part necessary to build fifteen different 14.13 radio circuits. The "EduKit" contains tubes, tube sockets, variable, electrolytic and paper condensers, resistors, tie strips, 5A (Libya) : 5A2TZ, 14.19; 5A4TU, 14.12 coils, hardware, tubing, Instruction Manuals, etc. No solder or hook -up wire Included.- A soldering iron is included, as well as Electrical and Radio Tester. Complete, easy -to- follow instructions are provided. All parts are guaranteed, brand new, carefully selected and matched. In addition, the "Edu -Kit" now contains lessons for servicing with the Progressive Signal Tracer, High Fidelity, F.C.C. Novice instructions, quizzes. TROUBLE -SHOOTING LESSONS Trouble-shooting and servicing are included. You will learn how to recognize and repair troubles. You will build and learn to operate a professional Signal Tracer. You will receive an Electrical and Radio Tester, and learn to use it for radio repairs. While you are learning in this practical way, you will be able to do many a repair job for your neighbors and friends and charge fees which will far exceed the cost of the "Edu- Kit." FREE EXTRAS ELECTRICAL & RADIO TESTER SOLDERING IRON HI -F1 GUIDE TV BOOK QUIZZES CONSULTATION SERVICE rPROGRESSIVE "EDU- KITS" INC., 497 Union Av., Brooklyn 11, N.Y. MAIL TODAY -Order shipped same day received. 30-Day Money-Rack Guarantee. INCLUDE ALL FREE EXTRAS "EDU -KIT" Postpaid. 1 enclose full payment of $19.95 'EDU -KIT" COD -1 will pay $19.95 plus postage (USA only) Outside USA: Enclose $20.95. "Edu -Kit" sent postpaid Outside USA; 210 -250V, AC /DC Adapter. Enclose $2.50 More, details on "EDU -KIT" Free -No Obligation FREE Radio -TV Servicing Literature. No obligation AME DDRESS

PROGRESSIVE "EDU- KITS" INC. 497 UNION AVE. Room 511D, Progressive Building Brooklyn II, N. Y.

August, 1955 123

AmericanRadioHistory.Com GLOSSARY OF ELECTRONIC TERMS

amplifier -A device of electronic components with or For the next several months, we will provide a without vacuum tubes to selected group of definitions of electronic terms, used increase power, voltage reprinted by permission from a booklet entitled or current of a signal. "A Dictionary of Electronic Terms," published by Allied Radio Corp., 100 N. Western Ave., Chicago, amplitude-Term used to describe the magnitude of a III. The complete dictionary, containing over 3500 simple wave or simple part of a complex wave. It is terms, is available from Allied at 25 cents a copy. the largest or crest value measured from zero. amplitude modulation -The common system of radio broadcasting. A battery -The battery used to supply power for the It consists of modulating a carrier frequency filaments of electron tubes. Sometimes loosely applied current by varying its amplitude above and to the filament power supply. below normal value in step with the audio frequency being transmitted. Abbreviated as AM. a.c. -d.c. -Term applied to electronic equipment indi- anode -The radio tube cating it is capable of operation from either an alter- electrode to which the main electron stream flows. It nating current or a direct current primary power is commonly called the plate, source. and is usually placed at high positive potential with respect to the cathode. Identified on diagrams by the adapter -Any device used for changing temporarily letter P. or permanently the terminal connections of a circuit array combination of or part. -A antennas or antenna elements so arranged that each reinforces the perform- aerial -A system of wires or electrical conductors em- ance of the other. Hence, an array is often used when ployed for reception or transmission of radio waves. a great amount of directivity and gain is required. Specifically, a radiator which couples the transmission attenuation- Reduction in the strength of an electrical line or lead -in to space, for transmission or reception impulse. of electromagnetic radio waves. Synonym: antenna. audio -Pertaining to currents or frequencies corre- air core-Descriptive term for coils or transformers sponding to normally audible sound waves. which have no iron in their magnetic circuits, and are audio transformer -An iron -core transformer to used chiefly in radio frequency circuits or for alternat- used ing current ammeter multipliers. couple two audio amplifier circuits. automatic frequency control -An electronic circuit align-To adjust or tune one or more circuits so that which keeps a superheterodyne receiver, or a trans- they operate to predetermined specifications. mitter, accurately tuned to a predetermined frequency. alligator clip -A long -nosed metal clip with meshing Used chiefly in FM receivers. Also used in receivers jaws used on test leads to make temporary connec- which are pushbutton tuned to correct slight inac- tions. curacies in the operation of the tuning system. Ab- breviated a.f.c. alnico -Alloy of iron with aluminum, nickel and co- balt, used to make permanent magnets for loud- automatic gain control- Abbreviated a.q.c. In a tele- speakers, motors, dynamotors, meters and motor -gen- vision receiver, a circuit which .performs the same erators. Has characteristic of holding magnetism function (for video and audio) as the a.v.c. circuit in indefinitely. Alnico is usually known by an alloy a radio receiver. number. Formerly, the alnico was a Alnico III; now autotransformer -Any transformer of single coil con- more powerful alloy has been created known as struction where the primary and secondary connec- Alnico V. tions are made to the single coil, and used to change alternating current-Electric currrent such as is usual- voltage amplitudes. ly supplied by power lines and produced by rotating baffle-A wood, metal or composition horn or flat machines. The ideal form is sinusoidal. Current re- surface used with a loudspeaker to increase the surging of sults from a back and forth electrons in the length of the air path from the front to the back of the lines. Current. flow from zero constitutes one cycle. loudspeaker diaphragm, thereby reducing interaction An alternation is half a cycle. The number of cycles between sound waves produced simultaneously by is the per second (cps) frequency. Power frequencies front and back surfaces of the diaphragm. A baffle are of the order of 60 cps; but the term a.c. is used in thus serves to direct the sound produced by a loud- connection with other frequencies to distinguish vary- speaker and improve the fidelity. ing frequency currents from d.c. components. banana jack-A receptacle that fits a banana plug. ammeter -An instrument to measure current flow in amperes. banana plug -A banana -shaped plug. Elongated springs provide a low- resistance compression fit. ampere -A practical unit of current. It is the current band -In radio, frequencies which are within two flowing through 1 -ohm resistance at 1 -volt potential. definite limits and are used for a definite purpose. The movement of 6,280,000,000,000,000,000 electrons Thus, the standard broadcast band extends from 550 past a given point in a circuit in one second corre- kc. to 1600 kc. sponds to a current of one ampere. Abbreviated amp. bandspread -Any method, mechanical or electronic, ampere turn -A unit of magnetomotive force, obtained of increasing space on tuning scale between stations by multiplying the current in amperes by the number otherwise crowded and difficult to tune. in of turns a coil. bandwidth -A section of the frequency spectrum re- amplification -The process of increasing the strength quired to transmit the desired information, whether of a signal, current, voltage or power, and usually visual, aural or both. The bandwidth of the overage produced by vacuum tubes, transformers and feed- television channel is 6 mc.; of a broadcast channel, back circuits. 10 kc., which is 1 /600 that of a television channel.

124 POPULAR ELECTRONICS

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bass booster, also bass boosting circuit - A group of B. & S. gauge -Brown and Sharpe wire gauge, the components connected in a circuit so that bass (low) standard gauge used in the United States to specify frequencies are emphasized. wire sizes. bass compensation -Any means, e:ectrical or acous- buffer amplifier -One or more stages of r.t. amplifica- tical, of offsetting the natural drop in the response of tIon used in a transmitter to build up the control crys- the human ear to low audio frequencies at low vol- tal frequency to an appropriate level before modula- ume levels. tion. This prevents feedback of undesired frequen- bass reflex -A type of speaker enclosure noted for its cies to the crystal. ability to enhance the bass characteristics of a loud- bug-A semi -automatic code transmitting key in which speaker. Bass reflex enclosures have a volume of up movement of a lever to one side produces a series of to 10 cubic feet and employ a port opening, the size dots, and movement to the other side produces a of which is determined by the volume of the enclosure single dash. and the cone resonance of the associated speaker. bathtub capacitor or condenser -A capacitor enclosed bus -Term used to specify an uninsulated conductor in a metal can with rounded corners like a bathtub. (a bar or wire). Usually square or round; may be solid or hollow. B battery -The battery used to supply the d.c. voltages required by the plates and screen grids of vacuum bypass capacitor or condenser -A capacitor used to tubes. provide a low- impedance path for radio or audio sig- beam power tube -A vacuum tube constructed with nals around a resistor or between a circuit terminal end shields so that the electrons are concentrated by and ground. emerging only at the two opposite sides. The two of which grids have parallel spacings to concentrate further the capacitance -The quantity electrical charge of conductors electrons in beams. The result is a sufficient electron can be received by a system insulated The term density near the plate to achieve the effect of a sup- from a potential source of given value. pressor grid which behaves as a virtual cathode. capacity is often used in this connection. A capacitor will more Performance is similar to that of a pentode. does not become filled but receive charge with increasing potential until breakdown occurs. obtained when signals beat frequency-The frequency Unit of capacitance is the farad. A one -farad capaci- combined recti- of two different frequencies are and tor requires one coulomb of charge to raise its poten- in value fied. The beat frequency is equal numerical tial one volt. A microfarad (pfd.) is one one -millionth to the difference between the original frequencies. (l0-6) of a farad. A micromicrofarad (µpfd.) is one one- bel -Unit of relative power, named after Alexander millionth of a microfarad or (10-í2) farads. Graham Bell, and used to express differences in pow- capacitor -input filter -A type of power supply filter er amplitudes. Generally used as 1 /10 bel, termed a which changes the pulsating d.c. output of a power decibel, and abbreviated db. supply rectifier to pure d.c. In this type of fitter, a bell wire -A common term for the cotton -covered B. & capacitor across the output of the rectifier precedes S. No. 18 copper wire used for making doorbell and an inductor or a resistor; there may be several such thermostat connections in homes. elements. Voltage regulation with this type of filter bias -The fixed voltage applied between grid and is not as good as when using the inductor (choke) cathode electrodes of a radio tube. Also called C input filter and ripple may become serious at high bias when speaking specifically of the control grid. currents. However, capacitor input filters offer the bias resistor-The cathode resistor through which advantage of about 55% greater output from a given plate and screen grid currents of a vacuum tube flow, voltage source than inductor input filters. developing across this resistor a d.c. voltage used as capacitive reactance -The reactance which a capaci- a C bias. tor offers to a.c. or pulsating d.c. It is measured in binaural effect-The effect of sound reaching both ohms, and decreases as frequency and capacity are human ears by which it is possible to locate the increased. source. sound capacitor -A radio part consisting of two conducting binding post -A terminal fixed in position and usually surfaces separated from each other by an insulating consisting of a threaded post to which wires may be material such as air, oil, paper, glass, mica or attached by means of one or more nuts. Binding posts ceramic. A capacitor is capable of storing electrical may be equipped with lugs or jacks. energy. In radio circuits, capacitors are used to block block diagram- Simplified outline of an electronic the flow of direct current while allowing alternating system in which circuits or parts are shown as and pulsating currents to pass. The capacitance of rectangles. a capacitor is specified in microfarads and micro - blocking capacitor or condenser -Any capacitor used microfarads. The capitance of a parallel plate capac- in a radio circuit to block the flow of direct current itor in air is equal to the area of the dielectric divided while allowing a.c. signals to pass. by 4 pi times the thickness of the dielectric. body capacity -The capacity existing between the capacity coupling, also capacitive coupling -A type human body and a piece of radio apparatus or of coupling :n which a capacitor provides a path for ground. signal. energy between two circuits or stages of an amplifier. breadboard- Laboratory idiom for an experimental circuit setup exposed on a board for portability and capacity -operated relay --A type of electronic relay ease of assembly or disassembly. circuit which is actuated by very small capacitance changes, such as those caused by bringing a hand breakdown voltage -The voltage at which the insula- near a pickup wire or plate connected to the circuit. two conductors or parts will break down. tion between Capacity- operated relays have many industrial ap- broadband -Ability of a circuit or antenna to be use- plications as safety devices. ful over a large frequency range and maintain voltage gain or amplification over this range. (To be continued next month) August, 1955 125

AmericanRadioHistory.Com STANDARDIZED WIRING DIAGRAM SYMBOLS

ANTENNAS MICROPHONE TELEGRAPH KEY SINGLE BUTTON DOUBLE BUTTON CAPACITOR

4 TRANSFORMERS FERRITE TYPE DYNAMIC VELOCITY3 CRYSTAL L GENERALTir DIPOLE LOOP

BATTERIES NEON BULB PILOT LIGHT AIR CORE IRON CORE AIR CORE --1111111P--- VARIABLE -SINGLE -CELL MULTI -CELL V BELL BUZZER l J 10 J l L PHONO PICKUPS PLUG OR SOCKET o Q..-

101 0 0 T CAPAC TORS IRON CORE POWDERED AUTO VARIABLE CORE O O _L CRYSTAL MAGNETIC 0 T CT. I T` FILAMENTS FIXED MICA RECEPTACLE 117V. RECORDING HEAD ELECTROLYTIC VARIAR E PRIMARY OR PAPER CAPACITORS GANG D / \ `_` MAGNETIC T 1 CT T \ /' 117V. HIGH VOLTAGE TRIMMER I" V OR ADDER SPLIT- STATOR FEED-7HRU RECTIFIER T-DESIGNATES TRIMMER OR PA DOER COILS SELENIUM TYPE FILAMENTS -X006L -68r80L alsbr- FI %ED R.F COIL POWER TRANSFORMER COILWITH FIXED COIL WITH RELAYS TAP VARIABLE TAP 0 TUBES -( 01c COI L OI CHOKE OR E PLATE CHOKE 1 O06Ò N- G RP SLUG-TUNED H H BIFILAR COIL S. PS T. 9 PST SPOT. NORMALLY OPEN NORMALLY CLOSED ERs CRYSTALS mo CATHODE RESISTORS DIODE R TRIODE TETROOE

H ..- -0-- MJM. PLATE CRYSTAL DETECTOR PIEZOELECTRIC GENERAL TAPPED ^ OR CAP CRYSTAL ADJUSTABLE GRID FUSE GROUNDS SURPRE$$OR CAP AM _ SCREEN POTENTIOMETER CONTINUOUSLY -- CONTROL OR RHEOSTAT CVARIABLE V /% DIODE SHIELDING SPEAKERS PLATE 1. WIRING CHASSIS PENTODE

HEADPHONES P.M. 11V1 DOTTED LINES¡ INDI- CATE SHIELDING V V COULD AROUND ELECTRO- DOUBLE SINGLE ANY COMPONENT OR MAGNETIC - -- GROUPS

L JACKS DESIGNATES SWITCHES GAS FILLED DUO TRIODE COLD CATHODE PHOTOC JC CUIT V'CLOSED CIRCUIT ELECTRIC BASE 2 S PS T S P DT 4 COLLECTOR V SHORTING TYPE BUTTON CIRCUIT 2 CIRCUIT `1 1 N-P-N TYPE SAME SYMBOL EXCEPT ARROW /+ IS REVERSED -y .yam EMITTER PHONE PIN PLUG I ,Ae ,e TRANSISTOR (JUNCTION) PIN JACK D P S.T. O. PDT. BOTH TYPES GANGED VIBRATOR WIRES METER MOTOR tit +-CONNECTION ROTARY ff-A TYPE O_. . $.P6P WAFER 'E. \ ' CONNECTION 126 POPULAR ELECTRONICS

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August, 1955 127

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Hi -Fi Distortion Another kind of distortion that occurs does not (Continued from page originate with the program mate- 83) rial injected to the system either. This takes present at the same time as the funda- the form of audible noise. It may be tube mental frequency causing the burst of oscil- hiss or other random noise of that kind lation, these may get "lost" during the oscil- which, if it is too loud compared to the pro- lation. gram material, can seriously mar the pro- Figure 2 shows the effect of the other gram; or it may take the form of a hum due kind of spurious oscillation. Here the ampli- to ripple voltages from the power supply fier goes into a continuous state of extreme- which get mixed up with the program ma- ly high- frequency (if not r.f.) oscillation terial in the amplifier. Hum may be of 60 which probably gives full output at its own cycles or can be of a higher frequency due frequency. However, since the diaphragm to the effect of the rectifier in multiplying of the loudspeaker cannot move at this high the frequency of the ripple. frequency, it has no effect in the room. In If the hum is relatively low in level com- fact, because the amplifier is completely pared to the program material, it may be loaded by the high frequency, it may sound just an annoying background that spoils even quieter than usual, i.e., the normal reproduction because of its presence. If it background hiss and hum level may appear gets a little stronger, however, it may also to be completely missing, even when the tend to break up the reproduction, like ear is put very close to the loudspeaker. But some kinds of intermodulation distortion, so when a musical program is put into the am- that the reproduction sounds choppy. This plifier, it chops up the spurious inaudible is due to the fact that the amplification of oscillation and manages to break through the program material changes during differ- here and there; while at the quieter pas- ent parts of the 60 -cycle wave. Thus, during sages of the program material, the oscilla- one part of the 60 -cycle wave, the program tion takes over completely and swamps out material is amplified more than it is during the audio. Figure 3 shows a typical wave- another part of the wave. The alternate in- form of an amplifier with program material crease and decrease in amplification during going through when it is suffering from the 60 -cycle wave has the effect of chopping spurious oscillation. up the program material. -[

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