Patent ID: 7816911
Filing Date: 2010-10-19
Classification: G01D,Y10T

Abstract:
1. A sensor comprising: an inductor having a variable reactance including: a housing having an open end, a closed end having a first passageway and an interior chamber; a coil support member disposed within said interior chamber and having a first end closing affixed to said closed end, a second end, and a second passageway extending through said coil support member from said second end and aligned with said first passageway, wherein said first and second passageway allow communication from said second end to the exterior of said housing; a coil of wire disposed on said second end having two or more lead wires extending through said second and first passageways from said coil to the exterior of said housing; an actuator configured and arranged to be slidably received in said interior of said housing, said actuator being coaxially disposed about said coil and said coil support member, wherein as said actuator is moved in and out of said housing, the inductance of said coil is affected; a sensor circuit including an oscillator circuit providing an output signal having a first frequency including: said inductor able to change said first frequency to a second frequency; first and second capacitors connected in parallel to one another and providing an electrical connection between ground and said variable reactance, said first capacitance having a capacitance having a positive temperature coefficient and said second capacitance having a negative temperature coefficient, wherein said first and second capacitors are selected reduce a temperature induced drift of said first frequency of said oscillator circuit.