Radio Broadcast - 1923, August - 86 Pages, 8.5 ... - VacuumTubeEra

Crystal Receivers are Well WorthWhileSome Types that are Simple to Put Together, Cheap,and of Value Both to Beginner and Confirmed EnthusiastBy ZEH BOTJCKAre you: interested in radio but without any experience in it; eager to enjoy the programs that fill theair, and to have the fun of building or operating your own receiver; broke or at least unwilling to pay"beaucoup francs" for apparatus which you think you cannot operate, to hear programs which you thinkyou may not care for? If so, get yourself a crystal set and have a taste of radio reception before tacklingvacuum-tube apparatus.Or, if already of the radio fraternity, are you building and rebuilding, soldering and unsoldering apparatusthat passes in a single week through the throes of super-regeneration and inverse duplex? If so, buildyourself a crystal receiver as a standby to tide you over whenever your tube set is bors de combat, so to speak.THE EDITOR.^^^""^^ H E advent of the dry-cell tube, and through its property of passing electricity inthe general drop in the price of only one direction, half the alternating currentvacuum-tube apparatus has by no issuppressed, leaving only that part travelingme* means sounded the knell of crystal in one direction (a direct current), whichreceivers. The advancement in bulb passes quite readily through the receivers.apparatus has been accompanied by similar There are several ways in which the radiostrides in crystal equipment, notably in the developmentof synthetic crystals which make the sound from an unamplified crystal set iswave may be delivered to the crystal, but aspossible fairly consistent reception over moderatelylong distances. Experienced operators the received wave, which is necessarily weak,actually furnished directly by the power ofstill recommend the purchase or construction only two methods, those making the most ofof crystal receivers by beginners, as the least the weak radio impulses, will be considered.expensive way of mastering the fundamentals The fact of direct power transformation, fromof tuning, and by the possessors of bulb apparatusas a standby when tubes burn out and frequency, should be constantly borne in mindenergy of radio frequency to energy of audiobatteries run down. When bulbs have suddenlyceased to function, many an interesting the necessity of painstaking construction tend-when building crystal apparatus, to emphasizeprogram has been "saved" by requisitioninga discarded crystal set. Also, a familiarity lessly made tube set may work, its imingto eliminate all possible losses. A care-with the theoretical and practical aspects of perfections probably being manifest in^ unps OET.crystal reception is of value in the operationand design of many reflex sets, in which acrystal is used as the detector.The crystal provides the simplest means ofdetecting radio signals, and isreception effectedby imposing the incoming radio-frequencyenergy on the circuit containing the^-detector, where it is "rectified." The radiocurrent, as the reader is probably aware, is analternating current and of so high a frequencythat, due to a phenomenon known as reactance,it cannot pass through the windingsFIG. 1of the telephone receivers. However, by means The preferred crystal circuit, which, with the additionof the indicated condensers, makes an excellent of rectification, which the crystal accomplishes set