File:Electrical instruments and telephones of the U.S. Signal corps (1911) (14569851510).jpg

Identifier: electricalinstru00unitrich (find matches)
Title: Electrical instruments and telephones of the U.S. Signal corps
Year: 1911 (1910s)
Authors: United States. Army. Signal Corps
Subjects: Military telegraph -- United States Military telephone -- United States
Publisher: Washington, Govt. print. off.
Contributing Library: University of California Libraries
Digitizing Sponsor: MSN

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)e with the horseshoemagnet in phice. ELECTRICAL INSTRUMENTS U. S, SIGNAL CORPS. 119 Generators used by the Sitjnal Corps are provided with o. 4. or 5bars, depending upon the chiss of service in which they are to beused. RECEIVER. A receiver of the type now used ahiiost exchisively in the SignalCorps is shown in tigure 73. It consists of a U-shaped permanentmagnet m. to the ends of Avhich are fastened soft-iron pole piecesp p. Over each pole piece is a coil of fine wire wound on a bobbinwith nonmagnetic metal heads. These coils are connected in series insuch a manner as to make the front end of one the north pole andthe similar end of the other the south pole wdien current flows throughboth coils in a certain direction. The combined resistance of thesecoils connected in series is about 80 ohms. The pole pieces passthrough the bottom of a metal cup 6, Avhich is thus secured firmly in
Text Appearing After Image:
Fi( -Hand receivti. place. The diaphragm ^7, of soft iron, tinned or enameled, restson the rim of this cup. A clamping ring / screws onto the metalcup C^ thus holding the diaphragm d firmly in place. The receivercords are connected to terminals t. a strain cord being attached tothe loop of the magnet to provide against injury to the cord con-ductors. As thus assembled the receiver is operative and may be soused in case of accident to the containing shell and cap. This shellaS* slips over the working parts of the receiver and is held in place bythe ear piece (/. which screws onto the shell. The separation of thediaphragm from the pole piece varies with the dirterent tyi:)es ofreceivers, the usual separation being about 0.01-1 inch. The operation of the receiver is as follows: _ The pole pieces p j>, being attached to the ends of the permanent magnet m, have one a north and the other a south polarity and the magnetic circuit is completed from one pole to the other through the soft ir

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