Impedance measuring circuit

Claim 1

IN COMBINATION, INPUT LINES INCLUDING A FIRST AND SECOND INPUT LINE ADAPTED TO BE CONNECTED TO A SOURCE OF POTENTIAL, A FIRST CIRCUIT CONNECTED DIRECTLY ACROSS SAID INPUT LINES, A SECOND CIRCUIT CONNECTED DIRECTLY ACROSS SAID INPUT LINES; SAID FIRST CIRCUIT AND SAID SECOND CIRCUIT COMPRISING A CURRENT RESPONSIVE DEVICE, A PLURALITY OF TRANSISTORS AND A PLURALITY OF IMPEDANCE ELEMENTS; SAID FIRST CIRCUIT INCLUDING SAID CURRENT RESPONSIVE DEVICE CONNECTED IN SERIES WITH THE COLLECTOR-EMITTER PATHS OF SAID PLURALITY OF TRANSISTORS, SAID SECOND CIRCUIT COMPRISING A VOLTAGE DIVIDER WHEREIN THE IMPEDANCE ELEMENTS OF SAID PLURALITY OF IMPEDANCE ELEMENTS ARE SERIES CONNECTED TO FORM THE VOLTAGE DIVIDER, SAID VOLTAGE DIVIDER INCLUDING AT LEAST ONE IMPEDANCE ELEMENT OF SAID PLURALITY OF IMPEDANCE ELEMENTS CONNECTED INTERMEDIATE THE REMAINING IMPEDANCE ELEMENTS OF SAID PLURALITY OF IMPEDANCE ELEMENTS; AND MEANS CONNECTING THE BASE ELECTRODES OF THE TRANSISTORS AT VARIOUS DIFFERENT POINTS IN SAID VOLTAGE DIVIDER SO AS TO OPERATIVELY ENERGIZE SAID CURRENT RESPONSIVE DEVICE ONLY WHEN THE IMPEDANCE OF SAID ONE IMPEDANCE ELEMENT FALLS WITHIN A PRESELECTED RANGE OF IMPEDANCE VALUES.