This is a basic level lazer alarm project. When anyone crosed or kept their hands on the lazer. buzzer starts working but when they took their hand from lazer light buzzer stops. But i want even after taking hands my buzzer should work for few (15-30) seconds .so please help me by giving idea..

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    Jul 25, 2021 at 6:43

1 Answer 1


If you are using a digital buzzer, you can do:


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