File:Electrical instruments and telephones of the U.S. Signal corps (1911) (14569911538).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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latter, the cabinets being bolted together in such a way as to, in allappearances, comprise one piece of apparatus. The protector equip-ment furnished usually consists of the Cook type L-8 or AVesternElectric type 81—B heat coils and carbon arresters. In addition, eachcabinet is equipped with sufficient line strips upon which to terminate 150 ELECTRICAL INSTRUMENTS U, S. SIGNAL CORPS. the incoming outside cable. This protector equipment will be de-scribed in further detail in another paragraph. The circuit of thesecentral energy visual supervisory switchboards is shown in figure 03, One neg lead iorall cords Q P Binding p istsfi <rtmns cord
Text Appearing After Image:
CENTRAL ENERGY LINE CIRCUIT Fig. Oa. which conforms very closely to commercial types, but embodies suchfeatures as are required for military i)urposes. Each cord is pro-vided with a two-coil visual supervisory signal, one coil on each side ELECTKICAL INSTRUMENTS U. S. SIGNAL CORPS. 151 or conductor of the cord, and a ringing and listening key. An exam-ination of the cord circuit will show that the supervisory signal alsoacts as a necessary impedance for the cord circuit. The signals andIheir impedances are bridged for the high frequency talking currentby a condenser in each side of the cord circuit. The ringing and lis-tening key is of the usual type, by which the operator can listen on theback cord by throwing the cam forward toward the cords or ringingon the front cord by throwing the cam toward himself. The connec-tions are made in the usual way by answering with the back cord, theoperator listening in by throAving his key cam and obtaining the num-ber of the party desired, then pl

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