Substation connecting arrangement

Claim 1

IN A TELEPHONE SYSTEM IN WHICH A TRANSMISSION LINE CARRIES DIRECT CURRENT, AUDIO CURRENT, AND CARRIER CURRENT, SAID SYSTEM INCLUDING A TELEPHONE SUBSTATION HAVING A CIRCUIT PATH THEREIN AND A FILTER CONNECTED BETWEEN SAID TRANSMISSION LINE AND SAID SUBSTATION (OPERATIVE TO SUPPRESS AT LEAST ONE OF SAID CURRENTS AND TO PASS THE OTHERS OF SAID CURRENTS), THE IMPROVEMENT WHICH COMPRISES A PLURALITY OF SEMICONDUCTOR SWITCHING MEANS, EACH OF WHICH IS OPERATIVE TO SWITCH FROM A HIGH IMPEDANCE STATE TO A LOW IMPEDANCE STATE RESPONSIVE TO THE COUPLING OF A DIRECT CURRENT VOLTAGE OF A PREDETERMINED POLARITY AND PREDETERMINED VALUE THEREACROSS, MEANS FOR CONNECTING SAID SEMICONDUCTOR SWITCHING MEANS BETWEEN SAID FILTER AND SAID TRANSMISSION LINE TO NORMALLY PROVIDE A HIGH IMPEDANCE TO THE FLOW OF SAID CURRENTS THEREOVER, AND AN ENERGIZING CIRCUIT INCLUDING SAID FILTER AND SAID CIRCUIT PATH IN SAID SUBSTATION FOR ESTABLISHING A VOLTAGE OF AT LEAST SAID PREDETERMINED VALUE ACROSS AT LEAST CERTAIN OF SAID SEMICONDUCTOR SWITCHING MEANS TO DECREASE THE IMPEDANCE OF SAID CERTAIN SEMICONDUCTOR SWITCHING MEANS, AND THEREBY PERMIT THE PASSAGE OF SAID CURRENTS THEREOVER TO SAID FILTER, SAID FILTER BEING OPERATIVE TO BLOCK SAID ONE CURRENT AND TO PASS THE OTHERS OF SAID CURRENTS TO SAID SUBSTATION.