Measuring and testing – Liquid level or depth gauge – Immersible electrode type
Patent
1984-09-21
1986-11-25
Yasich, Daniel M.
Measuring and testing
Liquid level or depth gauge
Immersible electrode type
324 61R, G01F 2326, G01R 2726
Patent
active
046241396
ABSTRACT:
A system for indicating level of material in a vessel as a function of material capacitance comprising a bridge circuit which includes a capacitance probe adapted to be disposed in a vessel so as to be responsive to variations in capacitance as a function of material level. An adjacent bridge arm includes a plurality of capacitors coupled to controlled electronic switches for selective connection into the bridge circuit. The bridge circuit is powered by an rf oscillator, and a differential amplifier is connected across the bridge circuit for detecting the balance condition of the bridge. An automatic calibration circuit includes a digital counter having outputs connected to the electronic switches. A comparator is responsive to the differential amplifier for enabling operation of the counter during a calibration mode of operation for selectively connecting the fixed capacitors into the bridge circuit until a preselected balance condition, corresponding to a preselected reference material level, is obtained. Thereafter, the differential amplifier is responsive to variation of probe capacitance from the reference level to indicate material level.
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Berwind Corporation
Yasich Daniel M.
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