Telephone interruption circuit with preset duration - has transistors and other components to provide operation independent of control mode, current and temp.

摘要

A circuit is used to provide an interruption of a current during a set period in a telephone line. The interruption time is independent of the control used, the value of the current and any variation in ambient temperature. The circuit has a set of contacts (rls) actuated by a relay (R1s) and a set of contacts (S1) actuated by a keyboard push-button. A bridge rectifier is used to protect the circuit against any reversed polarity. The circuit is connected to two terminals (ws, br) of a telephone. Two resistors (R1, R2), a capacitor (C), a load resistor (R), and two transistors (T1, T2) are connected to the relay coil (R1s) and a second set of contacts (S2) actuated the keyboard pushbutton.