Seiscor Technologies

Donald W Wortman

Dan Kesner Carter

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.

Subscriber line interface circuit providing regulated current

A power supply is provided with a predetermined nonlinear temperature coefficient for float charging sealed lead-acid batteries and providing power to a load. A temperature compensation network in the power supply provides the predetermined nonlinear temperature coefficient by using a linear temperature coefficient element (forward biased silicon diode) and a nonlinear temperature coefficient element (thermistor) in combination. Additionally, an over-voltage protection circuit, to disable the power supply should the output voltage exceed a predetermined value, is disclosed having a second temperature compensation network to compensate for the output voltage variation with temperature of the power supply.

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Bixby, OK, United States of America

Donald W Wortman