ON A CATEGORY OF DISPLACEMENT AND TEMPERATURE SENSORS BASED ON MAGNETIC-MATERIALS

The paper describes a displacement sensor and a temperature sensor. Bo th are based on series relaxation oscillations with tunnel diode and l inear coil. The active element of the displacement sensor is a coil wi th a soft ferrite core and a variable air-gap. The temperature sensor has as active element a coil with a toroidal core made of Invar alloy. The two sensor types are described and several characteristics of the output with respect to their different electrical and constructive pa rameters art discussed. The presented sensors exhibit excellent proper ties such as simple construction and simple electrical circuitry, smal l energy consumption, frequency stability for a large range of the sup ply voltage and a good linearity of the working characteristic. All th ese advantages make the presented sensors good candidates in a large a rea of industrial applications. (C) 1997 Elsevier Science S.A.