Electrical measuring apparatus

Claim 1

MEASURING APPARATUS COMPRISING A DIRECT CURRENT ELECTRICAL BRIDGE NETWORK HAVING AT LEAST ONE ELEMENT THEREIN WHICH IS REPRESENTATIVE OF A CONDITION TO BE MEASURED, MEANS CONNECTED TO SAID BRIDGE NETWORK TO ESTABLISH AN OUTPUT SIGNAL REPRESENTATIVE OF UNBALANCE OF SAID NETWORK, A DIFFERENTIAL DIRECT CURRENT AMPLIFIER HAVING FIRST AND SECOND INPUT TERMINALS, A FEEDBACK CAPACITOR CONNECTED BETWEEN THE OUTPUT OF SAID AMPLIFIER AND SAID FIRST INPUT TERMINAL, A SIGNAL STORAGE MEANS CONNECTED TO SAID SECOND INPUT TERMINAL, A RESISTOR HAVING THE FIRST TERMINAL THEREOF CONNECTED TO THE OUTPUT OF SAID MEANS TO ESTABLISH, A FIRST SWITCH TO CONNECT SAID FIRST INPUT TERMINAL TO THE SECOND TERMINAL OF SAID RESISTOR, A STABILIZING AMPLIFIER HAVING THE INPUT THEREOF CONNECTED TO THE SECOND TERMINAL OF SAID RESISTOR, A SECOND SWITCH TO CONNECT SAID SECOND INPUT TERMINAL TO THE OUTPUT OF SAID STABILIZING AMPLIFIER, TIMING MEANS TO CLOSE SAID FIRST AND SECOND SWITCHES SIMULTANEOUSLY AND PERIODICALLY FOR SELECTED TIME INTERVALS, AND MEANS TO APPLY THE OUTPUT OF SAID DIRECT CURRENT AMPLIFIER TO SAID BRIDGE NETWORK TO REBALANCE SAME.