Cumulative Timer

Published:2011/7/4 10:20:00 Author:Felicity | Keyword: Cumulative Timer | From:SeekIC

work of the circuit The circuit consists of resistor R1-R4, capacitor C, diode VD1-VD5, transistor V1, V2 and the crystal OSC BC. (It is showed in picture 8-144.) Turn on the power switch of the electronic instrument and the 220V voltage is limited by R1 and R2 and rectified by VD1-VD4. It produces 2.07V DC voltage on C. The timing begins. When the power switch of the electronic instrument is turned off, the voltage on C disappears. The frequency division circuit stops vibrating. But the frequency division circuit remains in the condition. When you turn on S next time, it begins to time again.



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