Radio today (Sept 1935-Dec 1936)

. . SIMPLICITY. . . . . QUALITY . . . PERFORMANCE Our background enables us to produce outstanding: speakers, which is the basis of our success. A complete line of PERMANENT DYNAMIC Speakers for Battery Sets, and P.M. Installations. Sizes 6 in., 8 in., 12 in. Permanent Dynamic Auto Speakers. 6 in., 8 in. and ."> ' , in. Header. Also a complete line of Electro Dynamic Speakers ranging in size from 5 in. to 12 in. Send us your specifications. RADIO SPEAKERS, Inc. Henry C. Forster, President 1338 S. MICHIGAN AVENUE, CHICAGO, ILLINOIS REGULATING WET ELECTROLYTIC CONDENSERS * The usefulness of leakage current in dry electrolytic condensers has been discussed in the preceding story by Mr. Peck. Recently a new type of wet electrolytic condenser has been developed that acts to keep the surge voltage down to a low value, according to the Aerovox Corp.'s engineering department. Ordinary wet electrolytic The first diagram shows the leakage characteristic of the ordinary wet electrolytic. Under normal operation at rated voltage the leakage is very low. However, as voltage increases beyond the normal peak voltage, current rises too, first slowly and then faster, until a point is reached where the condenser "scintillates." By "scintillation" is meant the repeated breakdown of the insulating film formed on the positive foil. After the breakdown, the film is reformed, only to break down again, followed by reforming, etc. This scintillation does not ruin the wet electrolytic condenser, for when the voltage is lowered again and the normal operating SCINTILLATION. PEAK VOLTAGE^ WORKING VOLTAGE, APPLIED VOLTAGE Leakage current characteristic of ordinary wet electrolytic. voltage applied, the condenser performs as well as ever. The characteristic of the new regulating type condenser is shown in the accompanying chart. Regulating condenser This regulating feature is utilized only during the interval when tubes are heating up, since a prolonged heavy current through the condenser would result in too great a temperature rise. When a set is first turned on, the rectifier tube heats considerably faster than the other tubes. During this period the tubes are drawing no plate current, and there may be no drain on the power supply save that for the filaments and the voltage divider. (To page 44) BUILDING AMPLIFIERS IS PROFITABLE and Easy! BUILD the STANCOR 18 Watt general purpose amplifier. Hundreds are doing it. Your jobber can supply the circuit and the chassis base with all holes punched, all tube sockets mounted, all transformers and chokes especially designed for this kit, two speaker output sockets, two input sockets, electric eye socket and built-in shelf for resistors. He can also supply all transformers and chokes at a very low price. All other parts are standard, inexpensive, and easily obtainable. Write or wire for literature, prices and liberal discounts. STANDARD TRANSFORMER CORP. 852 Blackhawk St. Chicago, Illinois FEATURES • IS Watts Output • New Electric Eye • All Metal Tubes • Operates 1 to 4 Speakers • Two Input Channels • Mixing System • Full-Range Tone Control • Plug-in Connections for Speakers • Easily Installed • Easily Operated MAIL THIS "STANDARD TRANSFORMER CORPORATION ■ 852 Blackhawk Street, Chicago, Illinois Please send me complete information on ■ Amplifier Kits. ■ Stancor a I ■ COUPON ■ 'em BIO FIGHT CONDENSERS Everybody in radio is watching this big battle between tubular TOBE TUBIDON and rectangular TOBE FLEXIDON! Some say TUBIDON will win out because it's easier to install . . . lower in cost . . . uses less space. Others favor FLEXIDON because of its "flexibility" . . . the fact that if because of an overload, one section breaks down, only the broken section need be replaced. Can YOU Pick The Winner? We'reneutral. We feel that both TUBIDON and FLEXIDON are great condensers . . . far ahead of others. But which is best ... TUBIDON or FLEXIDON... we leave that to you! See them in Person at all Jobbers ! You'll nnd TUBIDON and FLEXIDON at all good radio jobbers. InBpect them . . . give them a thoronghlworkout. Then put your faith in the .one you find best. Do yon want a catalog, and full technical description ? Please write today to TOBE DEUTSCHMANN CORP., DepU K-ll, Canton, Massachusetts. » ELECTROLYTIC CONDENSERS SKILLFULLY MANUFACTURED AT CANTON, MASS. 42 Radio Today K