| 摘要 |
PROBLEM TO BE SOLVED: To provide a capacitance probe for measuring and tracking changes in frequency and amplitude of parts during a high-cycle fatigue portion of a life test. SOLUTION: The capacitance probe 10 includes an internal oscillator 14, an adjustable receiver circuit 16, a product detector 18, and a pair of gain amplifiers 40 and 42. The oscillator generates a single controlled frequency output. The receiver circuit receives its frequency and generates a DC voltage deviation invalidating a capacitance bridge. The product detector detects the amplitude modulation product of the oscillator (90) and eliminates undesirable frequencies (92). The gain amplifiers detect the DC voltage deviation (100) and can easily invalidate capacitance effects.
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