Apparatus for detecting the presence, magnitude and direction of magnetic fields utilizing saturable magnetic core energized by alternating current

Claim 1

APPARATUS FOR DETECTING THE PRESENCE, MAGNITUDE AND DIRECTION OF D.C. MAGNETIC FIELDS COMPRISING AN ELONGATED MAGNETIC CORE IN THE FIELD TO BE MEASURED, SAID CORE HAVING A CENTRAL HOLE TO PROVIDE AROUND IT TWO MAGNETICALLY SATURABLE PATHS OF RESTRICTED CROSS SECTION, A PRIMARY WINDING PROVIDED ON SAID CORE SURROUNDING THE WHOLE CROSS SECTIONAL AREA OF THE CORE, MEANS FOR APPLYING AN ALTERNATING CURRENT TO SAID PRIMARY WINDING, SECONDARY WINDINGS WOUND RESPECTIVELY ABOUT SAID MAGNETIC PATHS OF RESTRICTED CROSS SECTION, RECTIFIERS CONNECTED RESPECTIVELY IN CIRCUIT WITH EACH OF SAID SECONDARY WINDINGS, SAID RECTIFIERS BEING SO POLED THAT RECTIFIED CURRENTS INDUCED IN SAID SECONDARY CIRCUITS BY SAID ALTERNATING CURRENT PRODUCE MAGNETIC FLUXES OF OPPOSITE DIRECTIONS LENGTHWISE OF SAID CORE TO CIRCULATE IN THE SAME SENSE AROUND SAID CENTRAL HOLE OF THE CORE, AND MEANS FOR DETECTING THE DIFFERENCE BETWEEN THE INDUCED D.C. VOLTAGES IN SAID TWO SECONDARY WINDINGS, VARIATIONS IN SAID FIELD SERVING TO VARY SAID INDUCED VOLTAGES.