Miller, Kempster Blanchard, 1870-1933 · New York : McGraw publishing company · leaf 514
hite lamp open. The circuit over which the relayD is normally energized may be traced from ground at therecording operators position through the coil of this relay, thencefrom the back contact of the relay B over one side of the trunk lineto the toll-switching operators position at the multiple… … FIG. 354.-COMPLETE WESTERN ELECTRIC TOLL CIRCUIT, SYSTEM A4D2 TOLL SWITCH-BOARD SYSTEMS. 493 line is in use and therefore the energization of the relay D nor-mally holds the circuit of the white lamp open. When the toll-switching operator plugged into the multiple jack of the subscribersline the…
Telephone
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