Abstract: An electric current sensor employing a Hall effect generator to be used in measuring electrical currents flowing in an electrical conductor. The sensor comprises an amplifier, a constant current source, a gapped toroid core mounted on the component side of a printed circuit board (PCB), a Hall effect generator extending via its output leads from the PCB into the gap of the toroid core, and an inductive loop positioned at the edge of the gap of the toroid core. The inductive loop itself comprises a simple trace formed on the component side of the PCB together with its plated-through-holes extending from the component of the PCB to the printed circuit (clad) side of the PCB. The PCB inductive loop placed at the edge of the gap of the toroid core and connected in series opposition to the output leads of the Hall effect generator, compensates for the unwanted induced voltages in the output leads of the Hall generator.

Abstract: Magnetic cores of clamp-on type current measuring devices having a Hall-effect device for measurement of D.C. currents are provided with stabilizing coils which are periodically energized to substantially eliminate the characteristic hysteresis effect of the core material. A magnetic core of the type which is split to permit opening and subsequent clamping onto a conductor, has one section thereof provided with an air gap in which the Hall-effect device is positioned. A stabilizing coil is positioned on one section of the magnetic core and the coil and is periodically energized with a damped oscillatory current. This damped oscillatory current is at least applied immediately prior to the taking of any current measurement and is preferably applied periodically to maintain the stability of the magnetic core.