Bidirectional selective remote connection and transmission circuit - detects or transmits audio signal after selection by relay of either high-impedance or low-impedance signal.

摘要

A speech path circuit (102) is connected between exchange line transformers (T1,T2) and a changeover switch circuit (50). A high-impedance-detection circuit (101) accepts a high-impedance signal from the exchange line for a switching circuit (30). A selector (SW1) connected to the transformers selects either a high- or a low-impedance signal according to the operation of a relay driver (107). An audio signal detector/transmitter (104) forwards the detected speech signal to the changeover switch circuit. USE/ADVANTAGE - For direct inward/outward dialling, circuit is automatically compatible for both incoming and outgoing connections without switch.