Signal transmission system for telephone line - uses opto-electronic couplers and limiters to isolate lightning over voltages

摘要

The signal transmission system allows signals to be transmitted via a line (e.g. a telephone line) subject to sudden overvoltages, (e.g. due to lightning) and provided with an earthed voltage arrester and an optoelectronic coupler at the receiver. The line (1tg) is coupled via a second optoelectronic coupler (OK1) to the transmitter (S). A signal amplifier (T) is connected between the line and the second optoelectronic coupler. Additional voltage limiting components Zener diode Z, diode D) shunt the line terminals and current limiters (resistors R3-R5) are connected in series with the line wire.