Threshold Magnetic Field Sensor Based on the Oscillator With a Magnetosensitive Piezoelectric Transducer in the Feedback

A threshold direct current magnetic field sensor with turn ON tunable level based on the oscillator containing a wideband amplifier, resistive voltage divider, as well as a resonance magnetosensitive transducer in the feedback loop has been described. The transducer is a bimorph plate of piezoelectric lead zirconate titanate with an electromagnetic coil wound on it. It uses a combination of the Ampere force, piezoelectric effect, and the acoustic resonance. The voltage transmission coefficient of the transducer depends on the dc magnetic field applied to the bimorph plate. Switching magnetic field of the oscillator can be tuned within the 5–600 Oe range by adjusting the parameters of the resistive voltage divider. The sensor is sensitive to the dc magnetic field direction.