Telephonic communications – Subscriber line or transmission line interface – Network interface device
Patent
1991-11-18
1992-08-11
Dwyer, James L.
Telephonic communications
Subscriber line or transmission line interface
Network interface device
379399, 379378, 379402, 379404, H04M 1900
Patent
active
051386585
ABSTRACT:
A subscriber line interface circuit that provides regulated current to telephone subscribers in an improved manner reducing the amount of power required to operate while maintaining a constant current source. The current to the telephone subscribers flows through a switching transistor, an inductive storage element, sensing resistors and a transformer. The desired operating characteristic is obtained by cycling the switching transistor. The switching transistor is cycled on at a preset interval causing the telephone subscriber current to flow from the switching transistor. The switching transistor is cycled off in response to an increase in the telephone subscriber current as sensed by the sensing resistors thereby causing the current to flow from the inductive storage element.
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Carter Dan K.
Wortman Donald W.
Clark William R.
Dwyer James L.
Seiscor Technologies Inc.
Sharkansky Richard M.
Shehata M.
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