| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem of a limit existing in measurement for needing a large dynamic range in a measuring range, the number of parts being numerous, experience needed for their adjustment and difficulty existing in performance holding. SOLUTION: A moisture sensor, whose electrostatic capacity changes is incorporated in an oscillation circuit system due to the difference of a dielectric constant of moisture, and change in the electrostatic capacity of the moisture sensor is converted into the change of a frequency with an oscillator. In this case, a capacitor is put between the moisture sensor and the oscillator. A CMOS timer is used in the oscillator.
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