An improved force transducer using amorphous ribbon cores

One potential use of magnetic amorphous ribbon materials is in force, stress or displacement transducers. This application relies on the high degree of stress sensitivity of magnetic properties exhibited by some amorphous materials. Mohri et al have described amorphous-core transducers composed of a two-core multivibrator circuit with a d.c. output. An improved transducer which produced an a.c. voltage output has been constructed and tested. An oscillator is used to magnetize an amorphous ribbon toroid by a primary winding via a buffer amplifier. The amplified output voltage from a secondary winding is directly proportional to the force applied to the toroid. This improved a.c. transducer system can be favourably compared to the d.c. system. The linear operating region has been improved to 350 g from 140 g for single core systems and to 400 g from 200 g for the double-core system. The repeatability and hysteresis of the two systems are comparable. Finally, this new a.c. device does not possess d.c. drift problems and is simpler to produce commercially.