Measuring and testing – Liquid level or depth gauge – Immersible electrode type
Patent
1979-11-13
1982-09-07
Yasich, Daniel M.
Measuring and testing
Liquid level or depth gauge
Immersible electrode type
324 60C, 324 61QS, 331 65, G01F 2326, G01R 2726
Patent
active
043477402
ABSTRACT:
A capacitance sensing circuit utilizes an operational amplifier connected in a comparator configuration. The capacitance to be measured is connected to one input of the operational amplifier and is also connected to the output of the operational amplifier through a resistor to form a free-running multivibrator. The period of the multivibrator output depends upon the value of capacitance being measured. A switching transistor is connected to the output of the operational amplifier to cause a changing current output signal. The output signal is obtained as a change of current in a current sensor connected to the collector of the transistor.
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Publ. "Simple OP-Amp Multivibrator Oscillator", Electronotes Mus. Eng. Group, Note No. 28, Feb. 25, 1977, pp. AN-1, AN-2.
Magnetrol International Incorporated
Yasich Daniel M.
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