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 172
ough its 250-ohm winding through the hook springs of theattendants telephone to the other terminal of the signal battery. Thiscircuit locks the relay until the attendant replaces her receiver on itsswitch-hook. When the attendant responds to the call she learns the number whichthe calling party… … To AutomaticPublic Exchange \ Fig. 154.—Trunk circuit to attendants station of a push-key inter-communicating system. The called person then presses his trunk key and holds conversation. When the attendant hangs up her receiver, the trunk relay unlocks,leaving the called station alone to hold the…
Telephone
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