Circuit arrangement for a telecommunication system with a centrally-controlled switching network

摘要

The switching network of a computer-controlled private branch exchange exhibits a number of series-connected switching stages (A, B, C). An audio switching network (T) is connected via two identical terminating resistors of 2 x 300 OMEGA (Z/2) to the two cores of the inputs of stage A. Via stage T, audio-frequency signals are transmitted to the speech wires, a DC bias voltage is applied to the transistors of the switching network during the signalling and the exchange line is terminated with 600 OMEGA during an enquiry. A power-feeding switching network is connected to the two output wires of stage B via two attenuating resistors (RD) and supplies the DC bias voltage during the internal calls. <IMAGE>