Telephone isolation device

Claim 1

AN ISOLATION DEVICE FOR INSERTION BETWEEN THE CONDUCTORS OF A TELEPHONE LINE AND A SUBSCRIBER TAP LINE, WHICH TAP LINE IS CHARACTERIZED BY UNAVOIDABLE SHUNT CAPACITANCE AND LEAKAGE RESISTANCE, COMPRISING A FOURTERMINAL NETWORK PROVIDING INDIVIDUAL PATHS FROM EACH TELEPHONE LINE CONDUCTOR TO A CORRESPONDING TAP LINE CONDUCTOR, EACH SUCH PATH INCLUDING A REVERSELY-POLED PARALLEL-CONNECTED PAIR OF NON-LINEAR RECTIFYING ELEMENTS INDIVIDUALLY CHARACTERIZED BY SUBSTANTIALLY ZERO IMPEDANCES FOR ABSOLUTE VALUES OF APPLIED VOLTAGE GREATER THAN THE EFFECTIVE VOICE-FREQUENCY SIGNALS CARRIED BY SAID TELEPHONE LINE AND A MUCH HIGHER IMPEDANCE FOR ASBOLUTE VALUES OF APPLIED VOLTAGE LESS THAN SUCH SIGNALS, AND AN INDUCTIVE REACTANCE ELEMENT SHUNTED ACROSS EACH SUCH PAIR OF RECTIFYING ELEMENTS.