| 摘要 |
A grain moisture meter has a test cell for containing a sample of the particulate material to be tested. A single oscillator includes a variable frequency tuned circuit including the test cell as a capacitor, a calibrated variable standard capacitor, a calibrating capacitor and a variable trimming capacitor. A frequency monitor generates DC voltage outputs of opposite polarity according to whether the output frequency of the oscillator is greater than or less than the selected frequency and displays the frequency difference as zero when the circuit is tuned. The calibrating capacitor is operator adjustable and a fixed reference capacitor and a reference number are provided to allow the operator to set the calibrating capacitor.
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