Sensitive Clap Switch Circuit

This is the circuit of a very sensitive clap switch. It switches ON/OFF a White LED or electrical appliances through claps. The circuit can sense the sound of claps from a distance of 1-2 meters. Condenser Mic picks up sound vibrations caused by the clap.
These sound vibrations are given to the inverting input (pin2) of IC1. It amplifies the sound collected by the Mic.

Resistor R2, R3 and variable resistor VR1 adjust the sensitivity of the amplifier. Resistor R1 set the sensitivity of Mic. The amplified output pulses from IC1 passes to the input of IC2 (CD 4017). Resistor R4 keeps the input (pin14) of IC2 low so as to prevent false triggering.

IC2 is a decade counter IC which is wired as a toggle switch. That its outputs 1 and 2 (pins 2 and 3) becomes high and low when the input pin14 receives pulses. Pin4 (output4) is connected to the reset pin15 so that further counting will be inhibited. The high output from IC2 passes through the current limiter R6 to the base of switching transistor T1. When T1 conducts, White LED (D2) turns on. If a 6V 100 ohms relay is connected to the points marked (A and B), the relay will also energize and the load (bulb or electrical equipments) will be switched on. In the next clap, output pin 2 becomes low and relay and White LED will be switched off. LED D1 (Red LED) indicates the OFF position.

PCB Layout of Sensitive Clap Switch Circuit

PCB Relay Pins
2 + 5 – Relay coil
1 – Common- Here connect the phase line
3 – NO ( Normally Open) – Here connect the load phase in series to switch ON the load when relay turns on
4 – NC ( Normally Connected) – Here connect the load phase in series to switch OFF the load when relay turns on

In the PCB layout, points A and B are used to connect relay coil pins 2 and 5


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  • Tarun baghel

    I am not able to construct the circuit using this image what should i do now confused about point( A B) relay connection

  • Jasmi

    Sir. I have done construct this project on breadboard but when I clap the led is not glow. Either the red or white. Can I know what is the problem? I hope you give response ASAP because I have to submit today. Tq sir

  • nayan

    hello sir
    i want to avoid disadvantage of clap switch circuit, can you help me to avoid this

  • nikhildalvi

    Which relay we have to use in this circuit??

  • alam khan

    Comment-my mic sensitivity is very very less how can increase mic sensitivity

  • garima

    plz tell me the connection of relay .which terminal is to be connected in point marked AB AND WHICH TO BE LEAVE as it is?

  • Eugene

    Thank you, the circuit definitely works!

    My one works kind of unstable – the clap can turn it state properly, but often it produces just momentary blink (so the state changes twice?) of one of the LED.

    First of all I thought that it’s positive feedback from Relay that I’ve connected to the output, because relay produces sound (I was able to even adjust sensitivity in a way to make it work in endless turn on-turn off cycle). But I’ve got rid of relay and the things do not changed much. Still sometimes it does not go to the next state, but one LED just blinks for a moment.

    Can it be somehow managed or it’s downside of this simple circuit?

    Attaching image and link to the video that shows caveat:


    • Khang

      No I mean i see in this schematic. The 13 and 15 relay pins aren’t conected. Just 2 and 5 to A and B point.

    • Eugene

      Did you mean 1,3,4? If so, then 1,3,4 it’s your two outputs: the first one 1-3 and second one 1-4. Then one output is connected another one disconnected.

    • Khang

      i wonder in this tutorial. The relay is conected 2,5 pins so how about 1,3,5??

  • syd subboh

    @jim keith I want little help. Actually I have some ideas to increase the sensitivity of the above circuit would you please help me in verifying my approach. Please send me your e-mail address.

    • syd subboh

      Sheikh Hassam would u please send me your design may be I can make some modifications in it.

  • sheikh hassam

    Stay on ……. No matter it deactivates on other clap…. Just stay on one clap

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