New force transducers using amorphous ribbon cores

New accurate, sensitive, and reliable force transducers are presented using amorphous ferromagnetic toroidal cores. These amorphous-core transducers are composed of a two-core multivibrator circuit with a dc output, in which Metglas 2826 ribbon-wound cotes (10 mm OD), which have high stress sensitivity, high yield stress, and high resistivity, are used. The linear-type transducer has higher linearity, higher stability against temperature variation, a fivefold increase in output voltages and currents, and a threefold increase in the maximum operating temperature when compared with conventional unbonded strain gauges. It can also be used as a variable-threshold-type transducer with a sharp transition behavior and small hysteresis by adjusting the values of resistors and by adding a diode to the linear-type transducer circuit. The amorphous-core force transducers are considered to be suitable for application in industrial automatic control under high temperature and high noise-level conditions.