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 309
Fio. 241.—A typical long distance call recording circuit equipped with discriminating tone agnala LONG DISTANCE AND SUBURBAN EQUIPMENT 285 private contact multiple of the connector bank. With this arrangement,whenever a plug was inserted in the jack, the earth connection that pulledup the cut-off…
Telephone
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