Pulse-output type magnetic sensors using plastically helical amorphous ribbons

New sensitive bistable magnetic sensors are presented using plastically helical formed amorphous magnetostrictive ribbons, in which sharp voltage pulses are induced between both ends of the ribbon against ac fields with amplitude of more than 1 Oe and frequencies of 0.01 Hz - 4 kHz due to the large Barkhausen effect and Matteucci effect. Experimental results for applications of these ribbons are also shown to simple rotational frequency sensors combining with a small magnet, simple ac-current sensors without pick-up windings, load and displacement sensors utilizing spring characteristics which makes it possible to construct acceleration sensors, and unilateral pulse transformers with the wide frequency band of 0.01 Hz - 40 kHz using inversely helical wound ribbon cores.