Circuit arrangement for the line feed of ancillary devices of a telephone set

摘要

For the line feed of ancillary devices of a telephone set, a shunt arm is inserted between the speech wires which shunt arm is formed by a reactance stage with a constant resistance characteristic. The reactance stage comprises, inter alia, a capacitor which is charged up once the operating voltage has been applied to the reactance stage. Until the reactance stage has attained its charged condition, a period of time elapses such that the desired electric response of the reactance stage is set only when the capacitor is in the charged condition. To reduce this charging time, the capacitor is charged directly via either a Zener diode or a switch monitoring the operating voltage of the ancillary device.