File:Electrical instruments and telephones of the U.S. Signal corps (1911) (14756240482).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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desired line is turnedup and the generator revolved. This will then call the line desired. As 164 ELECTHICAL lX.STRUME2vTS U. S. SIGNAL CORPS. soon as the call is nuule tlie key is then turned down and the two linesare cross connected. As there is no clearina-out drop, when a con-versation is finished the ring- oii will throw both drops, when theconnecting keys are then returned to their normal j^osition. Tsiniji:the row /, any two lines are cross connected by turnino- their corre-sponding keys in the same direction, remembering that the middlelistening key corresponds to the up position and the right-haiul one tothe down position in /. The combined ringing and listening key. //.is shown in section and plan in figure lOlh. A cross-connecting key of the row / is shown in plan and sectionin figure 102h, and is of the same general type as the preceding key,with the exception that it has eight instead of ten springs. Thesesprings are suj^plied with platinum contacts that are all normally
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open. The springs c of each key in figure 102b are connected to both fand (/ and r with / and ff. The construction of the listening key A is i:)lainly indicated. Thefirst cross-connecting strip is connected with the springs k and /.• ofthe left-hand listening key, the second cross-connecting row to similarsprings of the middle listening key, and the third cross-connectingrow to the corresponding springs in the right-hand listening ke).The receiver circuit is bridged across the springs I and /, and thebattery circuit across the s()rings m and n. When the lever or thelistening key is in the normal position all the contacts are open. Thewiring of the board is on same principle that is used in figure 10-t.explained in following paragra))h. J901 model.—The 1901 model is shown in figure lOli. and is of thesame eeneral construction as the one above described, the difference ELECTRICAL INSTRUMENTS U. S. SIGNAL CORPS, 165 coiisistinii in the rows of ringing and cross-connectig keys. Therea

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