Temperature compensated semiconductor strain gage unit

Claim 1

A BRIDGE CIRCUIT FOR MEASURING A FIRST CONDITION, SAID CIRCUIT COMPRISING, IN COMBINATION, FIRST, SECOND, THIRD AND FOURTH IMPEDANCE ELEMENTS, AT LEAST TWO OF SAID IMPEDANCE ELEMENTS HAVING A FIRST VARIATION IN IMPEDANCE IN RESPONSE TO SAID FIRST CONDITION AND A SECOND CONDITION AND A SECOND VARIATION IN THE RESPONSE TO SAID FIRST CONDITION IN RESPONSE TO SAID SECOND CONDITION, SAID VARIATIONS HAVING OPPOSITE ALGEBRAIC SIGNS AND DIFFERENT MAGNITUDES, A SOURCE OF POTENTIAL HAVING FIRST AND SECOND TERMINALS; SAID FIRST AND SECOND IMPEDANCE ELEMENTS BEING CONNECTED IN SERIES BETWEEN SAID FIRST TERMINAL AND A FIRST JUNCTION POINT, A SECOND JUNCTION POINT BETWEEN SAID FIRST AND SECOND ELEMENTS, SAID THIRD AND FOURTH IMPEDANCE ELEMENTS BEING CONNECTED IN SERIES BETWEEN A FIRST TERMINAL AND A FIRST JUNCTION POINT AND PARALLEL WITH SAID FIRST AND SECOND ELEMENTS, A THIRD JUNCTION POINT BETWEEN SAID THIRD AND FOURTH ELEMENTS; AND COMPENSATING MEANS FOR REDUCING THE NET EFFECT OF SAID FIRST AND SECOND VARIATIONS SUBSTANTIALLY TO ZERO, SAID COMPENSATING MEANS COMPRISING AN IMPEDANCE CONNECTED BETWEEN SAID FIRST JUNCTION POINT AND SECOND TERMINAL, THE IMPEDANCE VALUE OF SAID COMPENSATING MEANS BEING UNAFFECTED BY SAID SECOND CONDITION WHEREBY THE VALUE OF SAID FIRST CONDITION AND BEING SUCH AS TO SUBSTANTIALLY EQUALIZE THE MAGNITUDES OF THE EFFECTS OF SAID VARIATIONS ON THE OUTPUT VOLTAGE OF SAID BRIDGE CIRCUIT MAY BE DETECTED INDEPENDENTLY OF THE VALUE OF SAID SECOND CONDITION.