Telephone ringing circuit

Claim 1

A TELEPHONE RINGING CIRCUIT COMPRISING A RINGER AND CAPACITOR CONNECTED IN SERIES IN A SUBSCRIBER STATION, A LINE CIRCUIT COMPRISING A PAIR OF WIRES CONNECTED ACROSS SAID SERIES CIRCUIT, A LINE VOLTAGE SOURCE CONNECTED TO SAID CAPACITOR THROUGH SAID PAIR OF WIRES, SAID LINE CIRCIUT INCLUDING A SWITCHING TRANSISTOR HAVING INPUT AND OUTPUT ELECTRODES CONNECTED ACROSS SAID WIRES AND IN A PARALLEL CIRCUIT WITH SAID RINGER AND CAPACITOR, A BIAS SOURCE POLED TO MAINTAIN SAID TRANSISTOR NORMALLY NONCONDUCTING, RINGING CONTROL MEANS FOR SUPPLYING UNDIRECTIONAL CURRENT PULSES TO ACTIVATE SAID TRANSISTOR, AND MEANS INCLUDING A TELEPHONE TRANSMISSION CHANNEL AND TRANSMISSION GATE MEANS OPERABLE FOR CONNECTING SAID RINGING CONTROL MEANS TO SAID BIAS SOURCE WHEREBY SAID TRANSISTOR CONTROLS THE CHARGING AND DISCHARGING OF SAID CAPACITOR THROUGH SAID RINGER THEREBY CAUSING SAID RINGER TO PRODUCE AN AUDIBLE SIGNAL.