File:Electrical instruments and telephones of the U.S. Signal corps (1911) (14776394193).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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switchboard. Thus, beginning at the top. thisrow of disks is at the highest potential (120), and a conical i)lug in-serted, connecting any disk of this row with the line leading to thevertical strap through the jack at the bottom, will give the strongestcurrent, and so on down the rows to 10, which brings into the circuitonlv the last 5 cells next to the grounded end of the battery. The ELECTRICAL INSTRUMENTS U. S. SIGNAL CORPS. 69 low internal resistance of the storage battery permits feeding almostany number of lines out of the same row of cells without interference.The introduction of lamp resistances is necessary because of this lowinternal resistance of the cells, as a grounding of the line close to thetenmnal office would otherwise cause a current dangerous to the in-struments. The amount of lamp resistance to be inserted at eachpotential is, according to Jones, in his Pocket Edition of Diagrams,etc., 2 ohms for each volt. One ordinary 16-candlepower lamp Switchboard ppppppppp b
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^ I ■^^j ^^-tHIiII IIIM 5^ + ll 1 llll ltlllllll ) . 30 s 20 llll 10 I II Ihr Fig. 34. would be about right for the 110-volt potential, and two of these inparallel for the 50-volt potential. Telegraph Repeaters. THE MILLIKEN REPEATER. This was one of the earliest repeaters introduced into the telegraphservice, and it is still a standard repeater of the principal telegraphcompanies of this country. This repeater may perhaps be termed an automatic electro-mechan-ical repeater, for, while electricity is the controlling force in the per-formance of its automatic functions, the ultimate action is mechanical,as will be seen. Figure 35 is a theoretical diagram of the connections of the Millikenrepeater. R and R are the main-line relays. EM and EM areextra magnets, which, in practice, are supported on metal standards The descriptions and diagrams of the Milliljen and Weiny-Phillips repeatersare taken by permission from Mavers American Telegraphy. 70 ELECTRICAL INSTRUMENTS U. S. SIGNAL CORPS

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