. Electrical instruments and telephones of the Signal corps . t, varies withchanges in the pres-sure b e t w e e n thebodies. The changein resistance is due tovariation in the areaof contact surface be-tween the granulesand electrodes andnot to compression ofthe carbon granulesthemselves. In gen-eral, the transmittersused by the SignalCorps depend on thisprinciple. A typicaltransmitter is shownin figure 74. A metalcup, .1, forms thefront electrode and i-- attached to I he diaphragm for sending. Therear electrode is lield rigidly in a metal bridge i)iece. /% which is iuturn fastened to the
. Electrical instruments and telephones of the Signal corps . t, varies withchanges in the pres-sure b e t w e e n thebodies. The changein resistance is due tovariation in the areaof contact surface be-tween the granulesand electrodes andnot to compression ofthe carbon granulesthemselves. In gen-eral, the transmittersused by the SignalCorps depend on thisprinciple. A typicaltransmitter is shownin figure 74. A metalcup, .1, forms thefront electrode and i-- attached to I he diaphragm for sending. Therear electrode is lield rigidly in a metal bridge i)iece. /% which is iuturn fastened to the frame which supj)orts the mouthj)iece G, and theremainder of (he (raiisuiitter. This rear (lectrode consists of a hardpolished carbon button. J/, secured to a brass button between twoparts of which is clam]-)ed a mica ring or diajihragm. O, the outeredge of Avhich is claiii])e(l again-t the front ele<trode. .1. by means ofa metal ring. <^, Avhich screws over .1. The s]^ace between the frontand rear electrodes is partly filled with hartl granular carbon of. Vu;. 74.—T(l(i)Ii()iu liansniitter. ELECTRICAL INSTRUMENTS U. S. SIGNAL CORPS. 121 uniform size. Two dampenino; springs, B and (\ are provided toprevent vibration of the diaphragm at its natural j^erioch The operation of the transmitter is as follows: Current from a battery passes from one terminal, /i, to the carbonelectrode through the granular carbon to the metal cup which formsthe other electrode. If the transmitter now be spoken into, the dia-phragm and cup vibrate in unison with the sound waves producedin the air, thus causing the pressure betweeri the front and rear elec-trodes on the granular carbon to vary and thus change the resistanceof the transmitter. Therefore, variations in the current are set upwhich correspond exactly Avith the voice vibrations which reach thetransmitter diaphragm. RINGER. The magneto generator is commonly used in connection with apolarized bell or ringer, as it is usually called, by
Size: 1629px × 1533px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpublisherwashingtongovtprin
