A 0.1-500 HZ ANALOG THIN-FILM BH HYSTERESIS LOOP TRACER WITH AUTOMATIC Y-AXIS DRIFT CORRECTION

An analog magnetic hysteresis loop tracer is described that simply and effectively corrects for the Y-axis integrator offset drift inherent in hysteresis loop tracers. In order to keep a small input offset of a bout 30 mu V from being integrated over time into an output offset of volts, the integrator is reset once every cycle: A comparator is used to trigger a one-shot that engages a relay that discharges the integra tor capacitor. The circuit was built with standard available and inexp ensive parts, and allows stable BH hysteresis loop measurements to be made without Y-axis drift or distortion over a frequency range of 0.1- 500 Hz. (C) 1997 American Institute of Physics.