Electrical measuring system for measuring selected ones of a plurality of momentary input signals

Claim 1

AN ELECTRICAL STRAIN MEASURING SYSTEM COMPRISING: A PLURALITY OF SENSING CIRCUITS EACH INCLUDING AT LEAST ONE VARIABLE RESISTANCE SENSING ELEMENT; MEANS FOR APPLYING A UNIPOTENTIAL OPERATING VOLTAGE TO EACH OF SAID SENSING CIRCUITS TO DEVELOP, IN EACH OF SAID SENSING CIRCUITS, A VARIABLE D.C. SENSING SIGNAL REPRESENTATIVE OF CHANGES IN THE RESISTANCE OF THE SENSING ELEMENT THEREOF; SELECTOR MEANS FOR COUPLING SAID SENSING CIRCUITS, INDIVIDUALLY AND IN A PLURALITY OF DIFFERENT COMBINATIONS, TO A SINGLE OUTPUT CIRCUIT; A SOURCE OF A.C. SIGNALS OF SUBSTANTIALLY CONSTANT AMPLITUDE AND FREQUENCY; MODULATOR MEANS HAVING TWO INPUT CIRCUITS INDIVIDUALLY COUPLED TO SAID A.C. SOURCE AND TO SAID OUTPUT CIRCUIT, FOR GENERATING AN A.C. OUTPUT SIGNAL HAVING AN AMPLITUDE REPRESENTATIVE OF THE AMPLITUDE OF AN APPLIED D.C. SIGNAL FROM SAID OUTPUT CIRCUIT AND A FREQUENCY EQUAL TO THE FREQUENCY OF THE APPLIED A.C. SIGNAL; A PEAK DETECTOR, COUPLED TO SAID MODULATOR MEANS, FOR DEVELOPING A SUBSTANTIALLY UNIPOTENTIAL CONTROL SIGNAL REPRESENTATIVE OF THE AMPLITUDE OF SAID A.C. OUTPUT SIGNAL, AND A CONTROL CIRCUIT COUPLED TO SAID PEAK DETECTOR FOR ACTUATION BY SAID CONTROL SIGNAL.