Magnetic flowmeter

Claim 1

A MAGNETIC FLOWMETER COMPRISING A CONDUIT FOR FLUID OF WHICH THE FLOW IS TO BE MEASURED, MEANS PROVIDING AN ALTERNATING MAGNETIC FIELD TRANSVERSELY THREADING SAID CONDUIT, ELECTRODES ARRANGED ON A LINE EXTENDING TRANSVERSELY OF BOTH SAID FIELD AND THE PATH OF FLUID FLOW THROUGH SAID CONDUIT TO PICK UP SIGNALS RESULTING FROM THE FLUID FLOW THROUGH SAID FIELD, AND AMPLIFIER SHARPLY PEAKED AT THE FREQUENCY OF SAID FIELD RECEIVING SIGNALS FROM SAID ELECTRODES, MEANS PROVIDING A REFERENCE SIGNAL SYNCHRONIZED WITH SAID FIELD, SYNCHRONOUS PRODUCT-FORMING RECTIFIER MEANS RECEIVING THE OUTPUT OF SAID AMPLIFIER AND SAID REFERENCE SIGNAL AND PROVIDING AN OUTPUT IN THE FORM OF THE MATHEMATICAL PRODUCT OF INSTANTANEOUS VALUES OF THE OUTPUT OF SAID AMPLIFIER AND OF SAID REFERENCE SIGNAL, SAID SYNCHRONOUS RECTIFIER MEANS BEING IN THE FORM OF A HALL GENERATOR HAVING A MAGNETIC FIELD SYNCHRONOUS WITH THE FIELD THREADING SAID CONDUIT AND AN ELECTRICAL INPUT PROVIDED BY THE OUTPUT OF THE AMPLIFIER, AND MEANS MEASURING THE DIRECT COMPONENT OF SAID PRODUCT OUTPUT, THE LAST MENTIONED MEANS INCLUDING A SMOOTHING FILTER OF LONG TIME CONSTANT FOR THE SUPPRESSION OF TRANSIENT VARIATIONS OF SAID DIRECT COMPONENT.