Bridge compensating circuit

Claim 1

A CONTROL DEVICE FOR MEASURING AND/OR CONTROLLING A FIRST CONDITION, THE COMBINATION COMPRISING AN IMPEDANCE BRIDGE CIRCUIT INCLUDING A VARIABLE IMPEDANCE ARM FOR UNBALANCING SAID BRIDGE CIRCUIT IN RESPONSE TO VARIATIONS IN SAID FIRST AND A SECOND CONDITION; MEANS FOR ADJUSTING THE ZERO SETTING OF SAID BRIDGE CIRCUIT, SAID MEANS INCLUDING A FIRST COMPENSATING IMPEDANCE ELEMENT; MEANS FOR ADJUSTING THE SPAN SETTING OF SAID BRIDGE CIRCUIT, SAID MEANS INCLUDING A SECOND COMPENSATING IMPEDANCE ELEMENT; A SENSING ELEMENT PROVIDING AN OUTPUT SIGNAL IN ACCORDANCE WITH VARIATIONS IN SAID SECOND CONDITION; AND MEANS UTILIZING THE OUTPUT SIGNAL OF SAID SENSING ELEMENT TO CAUSE SAID FIRST AND SECOND COMPENSATING IMPEDANCE TO CHANGE IN ACCORDANCE WITH SAID OUTPUT SIGNAL TO COMPENSATE SAID BRIDGE CIRCUIT FOR VARIATIONS IN SAID SECOND CONDITION, SAID MEANS INCLUDING MEANS FOR INDEPENDENTLY ADJUSTING THE MAGNITUDE OF CHANGE IN SAID FIRST AND SECOND COMPENSATING IMPEDANCES FOR A GIVEN CHANGE IN THE OUTPUT SIGNAL OF SAID SENSING ELEMENT.