Telephone isolation apparatus

Claim 1

A TELEPHONE RINGER ISOLATION CIRCUIT FOR EACH SUBSCRIBER RINGER ASSOCIATED WITH RESPECTIVE TIP AND RING WIRES OF A TWO-WIRE TELEPHONE LINE FOR USE IN MULTI-PARTY TELEPHONE SYSTEM HAVING VARYING COMBINATIONS OF RINGING VOTAGES AND FREQUENCIES WITH AND WITHOUT DIRECT CURRENT POTENTIALS OR EITHER POLARITY TO PRESERVE ELECTRICAL LINE BALANCE BETWEEN SAID WIRES DURING TALKING PERIODS AND RESPONSIVE ONLY TO ALTERNATING CURRENT RINGING VOLTAGES FOR ACTIVATING ANY OF A SET OF RINGERS ASSOCIATED WITH A RESPECTIVE ONE OF SAID WIRES TO CONNECT SAID SET OF RINGERS TO SAID ONE OF SAID WIRES DURING OCCURRENCE OF SAID RINGING VOLTAGES, SAID CIRCUIT COMPRISING A FIRST SERIES CIRCUIT INCLUDING A NORMALLY NON-CONDUCTING TWO-ELECTRODE GAS TUBE AND AN INDUCTANCE COIL COUPLED BETWEEN THE ONE OF SAID WIRES BY WHICH THE ASSOCIATED RINGER IS ACTIVATED AND GROUND, A SECOND SERIES CIRCUIT ELECTRICALLY PARALLELING SAID FIRST SERIES CIRCUIT COUPLED BETWEEN SAID ONE OF SAID WIRES AND GROUND INCLUDING THE ASSOCIATED RINGER AND A VIBRATORY REED MAGNETIC SWITCH DISPOSED IN THE MAGNETIC FIELD OF SAID INDUCTANCE COIL HAVING CONTACTS RESPONSIVE TO MAGNETIC FLUX GENERATED BY SAID COIL TO CLOSE UPON APPLICATION OF SAID ALTERNATING CURRENT RINGING VOLTAGES TO SAID FIRST SERIES CIRCUIT, SAID GAS TUBE RESPONDING TO SAID RINGING VOLTAGES ON THE ASSOCIATED ONE OF SAID WIRES TO CONDUCT CURRENT THEREFROM THROUGH SAID COIL FOR CLOSING SAID SWITCH CONTACTS ONLY DURING OCCURENCE OF SAID LAST MENTIONED RINGING VOLTAGES.