1978-07-18
1980-01-22
Konick, Bernard
179 18BF, 179 99LS, H04M 172
Patent
active
041851730
ABSTRACT:
The disclosure is directed to a calling circuit which controls the connection of two different audio signal sources to a single audio signal transmission path for broadcasting the audio signals over a telephone set loudpseaker as well as controlling the energization of indicators in the telephone set and at the main control circuit. Only four conductors are used to connect the telephone set with the main control circuit, two of which are power supply conductors which may supply other circuits as well.
REFERENCES:
patent: 3763326 (1973-10-01), Murto et al.
patent: 3872261 (1975-03-01), Shinoi et al.
patent: 3872262 (1975-03-01), Kerman
patent: 3894197 (1975-07-01), Cowpland et al.
patent: 3904834 (1975-09-01), Shinoi et al.
patent: 3920902 (1975-11-01), Matsuo et al.
patent: 4081624 (1978-03-01), Kerman et al.
Hamatani Fumikazu
Kerman Stephen E.
Tanaka Yuji
Tsutsumi Fumio
Carten Francis N.
Konick Bernard
Myers Randall P.
Nippon Tsu Shin Kogyo K.K.
TIE Communications, Inc.
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