Abstract-A new high-performance, low-cost, capacitive position-measuring system is described. By using a highly linear oscillator, shielding and a three-signal approach, most of the errors are eliminated. The accuracy amounts to 1 pm over a 1 mm range. Since the output of the oscillator can directly be connected to a microcontroller, an AID converter is not needed.

Abstract-A new capacitive precision liquid-level gauge has been developed. The sensor consists of a low-cost planar electrode structure, a capacitance-controlled oscillator and a microcontroller. The device is able to measure absolute levels of conducting and nonconducting liquids with a 1 mm uncertainty over a 4 m range. The system has a high resolution of 0.1 mm at short measuring times of only 0.2 s. Slow level movements of 0.02 mm/h can be detected within 18 min.

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Abstruct-A very accurate capacitance-measurement system consisting of a discrete capacitance-dependent oscillator and a microcontroller has been developed. It can measure multielectrode capacitors with capacitances up to 2 pF, with an accuracy of 100 ppm with respect to a reference capacitor. The resolution amounts to 50 aF with a total measurement time of 300 ms.