Measuring and testing – Fluid pressure gauge – Diaphragm
Patent
1989-10-03
1991-01-29
Pellinen, A. D.
Measuring and testing
Fluid pressure gauge
Diaphragm
361283, G01L 912, H03B 1905
Patent
active
049877828
ABSTRACT:
A capacitive ratioing oscillator circuit utilizing a prior art pressure capsule, but through modification of the state variable oscillator circuit achieves a digital output which varies with the square root of the capacitance ratio C35 C.sub.p /C.sub.r. In this sensor the dielectric constant of the pressure media is measured in time with the pressure difference measurement. The oscillator includes a differentiator-inventor step herein each of capacitors C.sub.r and C.sub.p are connected to a common point and resistors are connected in parallel with each of said capacitors and with the common point connected to the inverting terminal of a first operational amplifier, a feedback line is connected from the output of the operational amplifier to the second resistor opposite the common point, first and second integrator circuits are connected to the output of said operational amplifier, a limit circuit is connected across the output of the second integrator circuit, and a feedback line is connected from the output of the second integrator circuit, and a feedback line is connected from the output of the second integrator circuit to the input of the inverter stage.
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A. J. Testani, "Oscillator," IBM Technical Disclosure, Dec. 1973, pp. 2042-2044.
Lepkowski James S.
Meyer Gerald W.
Pogany, Jr. Karl S.
Shkedi Zvi
Allied-Signal Inc.
Black Joseph R.
Johannssen Brian
Pellinen A. D.
Smith Robert C.
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