| 摘要 |
PURPOSE:To prevent malfunctioning due to frequency components below a specified frequency and noises in the detection of frequency components above the specified frequency, by counting the output frequency above the set value to clear it by a specified method. CONSTITUTION:A signal generated from a signal generation source 1 is extracted in terms of frequency components above a specified frequency with a bypass filter 2, compared with a set level with a level setting circuit 3 by a comparator circuit 4 and when the level is exceeded, an output VC is produced. The output VC is counted with a counter circuit 7 and when the counts value coincides with the value set with a counts value setting circuit 6, the detection signal is produced from the circuit 7, which is cleared periodically by a clear signal, the cycle of which is set for a value obtained by multiplying the cycle of the specified frequency as provided from a counting clearing circuit. Thus, malfunctioning due to frequency components below the specified frequency and noises can be prevented.
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