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Clap Controlled Electronic Switch by 555 Timer and 4013 D Flip-Flop
This electronic switch allows you to control an electronic device by only clapping your hands twice. It is based on three integrated circuits; 741 Op-Amp, 555 timer, and 4013 dual D flip-flop.
A 9V battery is ample to operate the circuit.
When you first clamp your hands, mic detects the sound and triggers the 555 timer via the operational amplifier. The timer stretches the signal and applies it to the clock input of the flip-flop. Because of the three state arrangement of the flip-flop , one more clamp is needed to change the output state. Second clamp sets the flip-flop output to high and this forward biases the 2N2222 BJT. Relay closes so the device connected to the relay switches on. Same procedure applies for the opposite. When you clap your hands twice, relay closes and turns off the device connected to it.
R3 trimpot adjusts the sensitivity of the circuit. You should turn it till the room noise does not effect the switch operation.