Digital long time delay circuit

Published:2011/5/10 22:31:00 Author:Christina | Keyword: Digital, long time delay | From:SeekIC

General long delay circuit usually needs the electrolytic capacitors or high impedance circuits. Theses delay circuit has the poor stability and low delay accuracy. Here is one kind of digital long time delay circuit, it completely abandons the large electrolytic capacitors and high impedance circuits, and it has high delay accuracy. The core component of this circuit is the MC14521B, it is a 24-stage frequency circuit and has the inverter. If you connect the trigger input port to the ground or do not add any signals, the circuit will get into the delay state, the delay time is controlled by the range switch X and the 100KΩ potentiometer. If we connect X with point A, the delay time is 1 minute 40 seconds to 18 minutes and 30 seconds. The delay time is adjusted by the 100KΩ potentiometer. If you need the longer delay time, you can use the large capacitor instead of the 39nF capacitor. At this time, the delay time will be more than one week. With the reliable and stable delay, we suggest you to use the 6 to 15V power supply. The prototype's voltage is 12V.



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