A resonant-type amorphous ribbon magnetometer driven by an operational amplifier

The resonant-type magnetometer presented here is composed of a high gain operational amplifier and a resonant circuit with an amorphous core connected to the input terminals of the operational amplifier. In this circuit, the operational amplifier with high input impedance operates a voltage switching element to invert the polarity of the driving voltage. Therefore, under the current source excitation, the duty ratio of the driving voltage is sensitive to a very weak dc magnetic field applied to the core. It is shown that the absolute value and the polarity of the mean value of the driving voltage can be converted into corresponding strength and direction of the de magnetic field. The maximum sensitivity of the magnetometer was around 12.4 V/Oe and the resolution was around 1.3×10^-6Oe.