Draw & explain touch plate switch using IC555.

Draw & explain touch plate switch using IC555.
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1 Answer

Answer :

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It is construct form monostable multivibrator , when metal plates touch by finger then voltage at pin number 2 goes to below 1/3 Vcc then output of lower comparator becomes high hence flip flop set and output of timer goes high at the same time external capacitor start charging towards Vcc and when the voltage across capacitor slightly greater than 2/3 Vcc then output of upper comparator goes high hence flip flop reset then output of timer goes low and it low till up to the metal plates touch by finger .

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