Amorphous wire MI micro sensor using C-MOS IC multivibrator

A family of sensitive, stable and low power consumption MI micro magnetic sensors are constructed using a CMOS IC multivibrator circuit, in which a sharp pulse train current is applied to amorphous wire to cause the skin effect. A micro field sensor having a resolution of 10(-6) Oe with a full scale (FS) of +/- 15 Oe and a nonlinearity of less than 0.2 %, a cut-off frequency of similar to 200 kHz, and a power consumption in the oscillation circuit of 0.5 similar to 5 mW is obtained using a zero-magnetostrictive FeCoSiB amorphous wire of 30 mu M diameter and 2 mm length. A differential field sensor is also constructed using a pair of amorphous wires suitable for detection of a localized field with the resolution of 10(-4) Oe cancelling uniform disturbance fields such as terrestrial field. Non-contact sensing of a magnetic card surface field was demonstrated.