Magnetic flowmeter apparatus

Claim 1

IN MAGNETIC FLOWMETER APPARATUS FOR PRODUCING AN OUTPUT SIGNAL CORRESPONDING TO THE FLOW RATE OF A FLUID, SAID APPARATUS INCLUDING A FLOW HEAD OF THE TYPE HAVING MAGNETIZING COIL MEANS ENERGIZED BY AN A-C. SUPPLY SOURCE FOR PRODUCING FLUX THROUGH THE FLUID, AND WHEREIN SENSING MEANS ARE PROVIDED TO DETECT THE ELECTROMOTIVE FORCE GENERATED BY FLUID MOVEMENT; THAT IMPROVEMENT IN SAID APPARATUS WHICH COMPRISES A TRANSMITTER INCLUDING AN AMPLIFIER HAVING AN INPUT CIRCUIT COUPLED TO THE SENSING MEANS OF SAID FLOW HEAD TO RECEIVE THE A-C. FLOW SIGNAL PRODUCED THEREBY AND ARRANGED TO PRODUCE A D-C. OUTPUT CURRENT CORRESPONDING TO ITS A-C. INPUT SIGNAL; A MAGNETICALLY-OPERATED FEEDBACK CONTROL DEVICE CONNECTED TO THE OUTPUT OF SAID AMPLIFIER TO RECEIVE SAID D.-C. OUTPUT CURRENT, MEANS TO DEVELOP WITHIN AN ELEMENT OF SAID DEVICE A MOVEMENT OF ELECTRICAL CHARGES CORRESPONDING TO SAID D.-C. OUTPUT CURRENT, A PAIR OF OUTPUT TERMINALS FOR SAID DEVICE, WINDING MEANS ENERGIZED BY SAID A.-C. SUPPLY SOURCE AND OPERABLE TO PRODUCE ALTERNATING FLUX WITHIN SAID ELEMENT TO CONTROL THE MOVEMENT OF SAID CHARGES SO AS TO DEVELOP BETWEEN SAID OUTPUT TERMINALS AN A.-C. VOLTAGE CORRESPONDING IN AMPLITUDE TO THE MAGNITUDE OF SAID D.-C. OUTPUT CURRENT AND TO THE AMPLITUDE OF SAID SUPPLY SOURCE VOLTAGE; AND CIRCUIT MEANS FOR COUPLING SAID A.-C. VOLTAGE TO SAID AMPLIFIER INPUT CIRCUIT IN SERIESOPPOSITION TO THE A.-C. FLOW SIGNAL PRODUCED BY SAID FLOW HEAD.