Circuit Schematics Diagrams and Projects

100 Seconds Duration On Switch with Touch Control by LM555

Touch Control Switch Diagram

Description

This is a touch controled switch which keeps the circuit on about 100 seconds after touching the plate connected to the 2 numbered pin. At the end of this time duration, relay releases and the circuit gets to off position.

The impedance of the trigger input of the 555 timer IC is very high and the inductive voltage on the human body is enough to trigger it. The circuit works based on this principle. You can use a piece of metal as a plate. The circuit can be used in toy circuits, buzzers or any project that is suitable. You can adjust the duration time by changing the R1 and C1 values.


Comments (2)

pido jarencio
I have built this circuit and it works very fine in our office sliding door. No need to use magnetic cards, just authorized finger prints will do. Thanks a lot!
dj augustine
this could be dangerous because it might be used for making timed bombs! but I hope NOT! Peace!

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