| 摘要 |
PURPOSE:To make a backup capacitor small and to obtain a reset to zero circuit having the wide range of application input frequency by inserting a voltage follower circuit and determining the attenuation constant of a meter driving circuit input signal voltage independently. CONSTITUTION:The voltage follower circuit 22 for reset to zero cuts off the output of an F/V converting circuit 21 and the input of a meter driving circuit 23 at the time of an electric power source off by a switch 32. Accordingly, the attenuation time constant of the input signal of the circuit 23 is determined independently of the time constant of smoothing circuits 26, 27 placed in the output side of the circuit 21. Accordingly, a capacitor 28 does not require a larger value compared with 26 and returns the pointer of a meter quickly to zero, and the backup capacitor 31 can be made small.
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