timer circuit fixing preset time

Published:2011/7/27 8:25:00 Author:Fiona | Keyword: Fixing preset time, timer | From:SeekIC

The 13 pin between Threshold value 1 and 2 absorbs the transistor's base current. If relay releases,it starts the switch process again through pressing the button after restoring time 0.5 S.Window discriminator TCA965 can constitute a timer.Capacity C which decides the time charges after pressing the button Ta ,transistor T1 gets the base current from TCA965's 2 pin,power supplys current.Rectification process times 10 S in advance.In some period indicator light LD57 is bright. When capacitor's charging voltage exceeds threshold value 1 ,the relay is closed.But when capacitor's charging voltage exceeds threshold value 2 after rectifying by potentiometer RP,the relay releases again. Relay's pick-up duration can be adjusted in 0 ~ 18 S.



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