| 摘要 |
This invention is a capacitance gage for measuring small distances wherein the frequency of an R-C oscillator is varied in proportion to changes in the capacitance responsive to changes in separation between a plate mounted with the gage and a grounded object whose distance is being measured. The gage plate is connected to the input of a Schmitt trigger circuit by means of a field effect transistor amplifier. The output of the Schmitt trigger circuit controls an electronic switch which alternately charges and discharges the probe capacitance in response to the output of the Schmitt trigger circuit between upper and lower voltage triggering levels and the charging frequency is taken in digital form at the output of the switch. The variable frequency output is suitable for high-accuracy, non-contact dimensional inspection with digital readout or direct computer processing. The gage further provides improved performance for medium to high-resistance materials and can be compensated to provide a low temperature drift.
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