Electrical instruments and telephones of the U.S. Signal corps (1911) (14756206662)

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

Text Appearing Before Image:

pen, as in figure, the cir-cuit of the left-hand coil of the extra magnet of the eastern relay isopen at the left-hand post of the western transmitter, and as a resultthereof that extra magnet is magnetized by the current passingthrough the right-hand coil, and hence the armature lever of that re-lay is held against its front stop. Thus, for example, when, as in thefigure, the west sends to the east, and thereby opens his key, the west-ern relay in the repeating office opens and its armature lever fallsback, opening the local circuit of the western transmitter. As this OF THE 72 ELECTRICAL INSTRUMENTS U. S. SIGNAL CORPS. transmitter opens it first breaks, at its left-hand post, the circuit ofthe left-hand coil of the extra majrnet of the eastern relay, and nextopens the eastern main line circuit at the rijrht-hand post. As. how-ever, the armature of the eastern relay is kept closed in the mannerstated by its extra magnet, the eastern circuit remains unbroken in therepeating station. -

Text Appearing After Image:

The local battery, it will be seen, is also utilized to operate its re-spective transuiitter. A button switch is placed on the base of eachtransmitter for the purpose of short-circuiting the main line contactpoints on the transmitter when it is desired to use the transmittershnply as a sounder for the relay. ELECTKICAL INSTRUMENTS U. S. SIGNAL CORPS. 73 DUPLEX TELEGRAPHY. By duplex telegraphy is meant the sending of two messages overone wire in opposite directions, that is, one from each end of the wire,simultaneously. In ordinary Morse, or single-wire Avorking, signals can only betransmitted by one station at any one time, because the opening ofany one of the keys operates all the instruments on the circuit. To make duplex telegraphy possible, therefore, it is essential thatthe signals transmitted from the home station shall not interfere with,the signals to be received at the home station. The home receivinginstruments at each station must consequently be so constructed or soplaced

electrical instruments and telephones of the u s signal corps 1911 book illustrations government printing office military transmitter radio united states army images from internet archive

1911

University of California

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public domain