Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 440
iallywound, and the signals are therefore displayed as long as current istraversing them. In addition to the supervisory signals and theusual ringing and listening keys, each cord circuit is provided withtwo keys, K and K, each serving, when operated, to cut off batteryfrom its cord and at the same… … TIG. 315.—CORD CIRCUIT FOR PRIVATE-BRANCH EXCHANGE SYSTEM. When two private branch lines such as are shown at the leftof Fig. 313 are connected by the private branch cord circuit, thekeys, K and K are left in their normal positions. Current is thenfed to each subscriber for talking through the two…
Telephone
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