Capacitance-type liquid level measuring probe
AssigneeTektronix, Inc.
InventorThomas R. Kessinger
Life of this patent
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Abstract
A capacitance-type liquid measuring probe 10 includes two concentric metallic tubes 12 and 14 extending downwardly into a tank of oil. The concentric metallic tubes 12 and 14 form the plates of a capacitor. The probe 10 measures the oil level in the tank during jet engine testing by detecting a change in electrical capacitance between the two concentric metallic tubes 12 and 14, the capacitance change being caused by a change in the level of the oil. The measuring circuitry 30 includes thermal compensating resistors and a temperature-stabilized detector. The measurement electronic circuit package is separately-housed and connected to the probe 10 via a cable 44 so that the circuitry 30 can be located remotely from the hot environment in which the probe 10 operates.
Claims11
A liquid level measuring probe comprising:
- a capacitive sensor extending into a liquid in a tank with the capacitance of the sensor changing depending on the level of the liquid;
- an electronic circuitry for providing a signal representing the level of the liquid by detecting the capacitance of the capacitive sensor, said electronic circuitry being located remotely from the capacitive sensor and comprises a temperature-stabilized detector including at least two transistors;
- and
- a cable for electrically coupling the capacitive sensor to the electronic circuitry.
Dependencies are inferred from the claim text.