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US 4,392,378 AGranted
Capacitance measuring apparatus
Assignee501 Ferranti Limited
InventorsBrian E. Pitches, Robert M. S. Murray, Douglas J. Rogers
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Assignee501 Ferranti Limited
InventorsBrian E. Pitches, Robert M. S. Murray, Douglas J. Rogers
Estimating the term…
Capacitance measuring apparatus comprises a variable capacitor VC and a reference capacitor FC. Circuits D, ID, are provided for generating a periodic waveform for application directly to the variable capacitor, and in inverted form to the reference capacitor. Switches means SM are operated by control logic CL to connect the two capacitors in sequence to the input of an integrating amplifier IA, the output of which is applied to a comparator CM to which is also applied a reference level. The output of the comparator controls the control logic. Output of the control logic is converted to an indication of the capacitance of the variable capacitor relative to that of the reference capacitor.
Capacitance measuring apparatus which includes a variable capacitor and a first reference capacitor, means for generating a periodic voltage waveform for application directly to the variable capacitor and means for generating the periodic waveform in inverted form to the reference capacitor, an integrator, switching means for connecting the variable capacitor and the reference capacitor sequentially to the input of the integrator, comparison means for comparing the output of the integrator with a reference level, control means responsive to the output of the comparison means to control a sequence of operation of the switching means and to deliver an output pulse train, and output means responsive to the output pulse train to determine the capacitance of the variable capacitor relative to that of the reference capacitor.
Capacitance measuring apparatus which includes a variable capacitor and a first reference capacitor, means for generating a periodic voltage waveform for application directly to the variable capacitor and means for generating the periodic voltage waveform in inverted form to the reference capacitor, an integrator, switching means for connecting the variable capacitor and the reference capacitor sequentially to the input of the integrator, comparison means for comparing the output of the integrator with a reference level, control means responsive to the output of the comparison means to control a sequence of operation of the switching means and to deliver an output pulse train, and output means responsive to the output pulse train to determine the capacitance of the variable capacitor relative to that of the reference capacitor in which the variable capacitor is arranged to be immersed in a dielectric liquid, the apparatus being operable to determine the depth of the liquid in a tank in which the variable capacitor comprises a pair of concentric tubes of electrically-conducting material extending for the full useful depth of the tank.
Dependencies are inferred from the claim text.