INTERFACE CIRCUIT IN EXCHANGE

摘要

The circuit comprises a hybrid circuit(1) not to mix the transmitting and receiving signals, a frequency detectors(2,3) selecting 2250 and 2600 KHz from the output of the hybrid circuit, an interface circuit(4) connected to a CPU, a switching circuit(5) switching a transformer(T) and voice network terminals(VN1,VN2), an analog switch(6) controlling a buffer(BF) passing a signal of 70Hz, an analog switch(7) passing the output of the buffer with a response/ call control signal, and an analog switch(8) providing the output of the switch(7) and the voice signal of the transformer to a transmission transformer(HY1).