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 207
ngs to the night telephone. When the operator plugs in to make a night call, the battery reversalon the trunk operates relay P, which pulls up relay C to busy the selectorbank, and pulls up relay A which switches the night telephone from itslineswitch to the trunk. The operator then rings the…
Telephone
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