Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 372
subscribers are talking, but assoon as either subscriber hangs up his receiver the armature of relay5 or S, will drop back, thus closing the circuit of the relay, B or B,which relay will then receive current over the following circuit:From the ungrounded pole of the battery through the… … 350 THE COMMON BATTER-Y MULTIPLE SWITCH-BOARD. 351 relay, B or B. Upon the actuation of the relay due to this currentthe circuit of the corresponding supervisory: lamp will be complete,which lamp will light and remain lighted until the operator pullsdown the connection. The test of this circuit…
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