| 摘要 |
PURPOSE:To hold a peak value exactly by comparing a period of the discharging timing of a capacitor and the A/D conversion timing of capacitor voltage with the reference time and by discriminating whether the capacitor voltage should be stored or not. CONSTITUTION:When pseudo sine wave SWAVE exceeds reference voltage REF1, a comparing circuit 1 outputs a signal CMP1 and a monostable multivibrator 3 discharges the capacitor of a peak detecting part 6 and starts an operation of a timer 7. When the signal CMP1 falls, a monostable multivibrator 4 is operated and an AD transducer 8 digitally converts a peak value P of a peak detecting part 6 and the operation of the timer 7 is stopped. When a monostable multivibrator 5 outputs a set pulse SET in accordance with the output of a comparing circuit 2, if the measured time of the timer 7 is smaller than the reference value, an AND circuit 10 outputs a storage controlling signal MEMC and an AD conversion 8 output of a peak value is held in a storing part 9. While, in case of the long charge holding time, the peak value is not stored. |
