Telephone transit exchange with line detector for call charge pulses - has transistorised circuit connected to line and switch contacts at outgoing junction

摘要

The telephone exchange equipment is used to retransmit call charge pulses when no special line is provided for such signals. The equipment includes an incoming junction, an auto-selector and an outgoing junction. A detector is added to the incoming junction line and a set of contacts is added to the outgoing junction line. The detector can detect a change in voltage in the line corresponding to call charge pulses. It has a transistorized circuit connected to the transit line (t). The change in voltage of the line (t) drives one (T2) of the transistors which in turn polarises another transistor (T3). Saturation of this transistor (T3) provides a voltage to a relay coil (R). The contacts of the relay (R) produces a signal for retransmission of the call charge pulses.