Automatic telephony; a comprehensive treatise on automatic and semi-automatic systems (1921)
Smith, Arthur Bessey, b. 1875, Campbell, Wilson Lee · New York : McGraw-Hill · leaf 284
t M-2 drives the wipers over the bank. Relay #-11also connects up the testing circuit from ground through relay #-10 tothe wiper W-S-200. Wire 79 leads to the control relay #-32 (Fig. 225)of the key-set switch. If the position is not busy and is ready for thereception of a call, the control relay… … Fig. 226.—Identifying the calling line switch (Fig. 225) contact on operators receiver jack. If an operatorleaves her position she will withdraw the receiver plug cutting off thenegative potential from the control relay and wire 79 and making herposition busy. When the wipers of the secondary…
Telephone
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