KEY TELEPHONE LINE SHUNT DETECTOR CIRCUIT

摘要

KEY TELEPHONE LINE SHUNT DETECTOR CIRCUIT A line circuit is disclosed for controlling communications over a communication pair between a switching machine and a key telephone station. The line circuit includes a dual sensitivity shunt detector arrangement for improved detection of dc transients and ac ringing voltage signals appearing across the pair. A current diverter circuit switches the sensitivity of the shunt detector arrangement depending on the operating state of the key telephone station.