Subscriber loop current regulator

摘要

A current regulator for supplying dc power to a telephone line employs a resistor feed circuit in conjunction with a solid state feed circuit. The dc line current flowing through both such elements is monitored by a sensing circuit which drives the solid state element in a manner to maintain a desired magnitude of dc line current. The resistor value may be arbitrarily chosen so that the circuit power is shared in a desired proportion between the resistor and solid state element. When used in a telephone line in series with ac voice signals the regulator employs a capacitator and diode bridge arrangement to reduce the ac impedance thereof, improve longitudinal balance and allow bi-directional current.