Automatic rebalancing measuring circuit including a phase shifted photomodulator

Claim 1

THE COMBINATION COMPRISING: A PAIR OF TERMINALS ADAPTED TO BE CONNECTED TO A SOURCE OF ALTERNATING CURRENT; PHASE SHIFTING MEANS CONNECTED TO SAID PAIR OF TERMINALS FOR PRODUCING A MODULATION SIGNAL THAT IS IN SUBSTANTIALLY QUADRATURE PHASE RELATION WITH SAID SOURCE OF ALTERNATING CURRENT; AN INPUT TERMINAL FOR APPLYING INPUT SIGNALS; A SOURCE OF REFERENCE SIGNALS COUPLED TO A REFERENCE TERMINAL, SAID SOURCE OF REFERENCE SIGNALS INCLUDING ADJUSTABLE MEANS FOR VARYING THE AMPLITUDE OF REFERENCE SIGNALS APPLIED TO SAID REFERENCE TERMINAL; AN AMPLIFIER CIRCUIT; A PHOTOMODULATING CIRCUIT CONNECTED TO SAID INPUT TERMINAL AND SAID REFERENCE TERMINAL FOR MODULATING SAID INPUT SIGNALS AND SAID REFERENCE SIGNALS APPLIED THERETO AND DEVELOPING MODULATED SIGNALS AT AN OUTPUT TERMINAL; CIRCUIT MEANS CONNECTING SAID PHOTOMODULATION CIRCUIT TO SAID PHASE SHIFING MEANS FOR APPLYING SAID MODULATION SIGNAL THERETO SO THAT SAID INPUT AND REFERENCE SIGNALS ARE MODULATED TO PROVIDE MODULATED SIGNALS AT SAID OUTPUT TERMINAL IN ONE OF A LEADING AND A LAGGING QUADRATURE PHASE RELATION WITH SAID SOURCE OF ALTERNATING CURRENT, THE AMPLITUDE OF SAID MODULATED SIGNALS AND SAID ONE OF SAID LEADING AND LAGGING QUADRATURE PHASE RELATION BEING A FUNCTION OF THE AMPLITUDES OF SAID INPUT SIGNALS AND SAID REFERENCE SIGNALS; CIRCUIT MEANS CONNECTING SAID OUTPUT TERMINAL TO SAID AMPLIFIER CIRCUIT FOR AMPLIFYING SAID MODULATED SIGNALS; A MOTOR HAVING FIRST AND SECOND WINDING, SAID MOTOR BEING ADAPTED TO GENERATE A ROTATIONAL TORQUE IN RESPONSE TO SIGNALS APPLIED IN SUBSTANTIALLY QUADRATURE RELATION TO SAID FIRST AND SECOND WINDINGS, THE ROTATIONAL TORQUE BEING IN A DIRECTION DETERMINED BY THE LEADING AND LAGGING PHASE RELATION OF SAID SIGNALS APPLIED TO SAID FIRST AND SECOND WINDINGS; CIRCUIT MEANS COUPLING SIAD FIRST WINDING TO SAID PAIR OF TERMINALS FOR ENERGIZING SAID FIRST WINDING BY SAID SOURCE OF ALTERNATING CURRENT; CIRCUIT MEANS COUPLING SAID AMPLIFIER CIRCUIT TO SAID SECOND WINDING FOR APPLYING AMPLIFIED MODULATED SIGNALS THERETO, AND MEANS FOR COUPLING SAID MOTOR TO SAID ADJUSTABLE MEANS TO VARY THE AMPLITUDE OF REFERENCE SIGNALS APPLIED TO SAID REFERENCE TERMINAL SO THAT SAID MOTOR SUPPLIES THE NECESSARY TORQUE TO SAID ADJUSTABLE MEANS TO REDUCE THE MODULATED SIGNALS DEVELOPED AT SAID PHOTOMODULATOR OUTPUT TERMINAL.