Unmagnetized amorphous ribbon transducers

The linear stress sensitivity of amorphous ribbons make them suitable materials for transducer and sensor devices. The most common device consists of an amorphous ribbon toroid with two windings. The primary winding magnetizes the toroid and the variation of the secondary winding voltage with applied force is the transducer characteristic. It has been shown that the applied force causes a change in the domain wall motion or if the toroid is unmagnetized produces a domain wall motion. This latter property has enabled a new type of amorphous ribbon transducer to be developed. The unmagnetized amorphous ribbon transducer reported here consists of a toroid with a single output winding. The performance of a series of unmagnetized stress sensors has been measured. The sensitivity of these sensors to impulse forces has been investigated. These characteristics of the sensors will be fully presented. An increase in the sensitivity can be achieved by annealing the specimens or by saturating the toroid with an adjacent permanent magnet. The increase in sensitivity has been shown, by Kerr magnetooptic observations on as-cast and annealed samples, to be due to an increase in wall mobility produced by the stress relieving effect of the annealing. This paper introduces a new type of magnetic amorphous ribbon transducer which is simple, reliable, rugged and does not require an electrical supply. Possible applications of these devices are proposed.