| Summary: | 碩士 === 大同大學 === 機械工程學系(所) === 92 === This article focuses on capacity type humidity sensors to design sensor circuits and this research adopts oscillator circuits as a design architecture to derive two sensor signal conversion platforms for the capacitance type humidity sensor and these two platforms are capacitance-to-frequency and capacitance-to-voltage converters.
For the capacitance-to-frequency converter circuit, the Intel 8254 chip is integrated in the circuit to count the change of the frequency. For the capacitance-to-voltage converter circuit, the concept of phase pulse modulation is adopted in the oscillator circuit mode design, and the output voltage increases with increase the magnitude of the pulse.
The value of humidity sensor varies from 30 %RH to 80 %RH in the test channel at 25℃, then the frequency is measured between 6334 Hz and 6334Hz. The out voltage in the capacitance-to-voltage converter circuit is varied from 1.21V to 1.44V.
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