Sound Activated Switch – Relay

Rajkumar Sharma  
Project tested


This project is a sound activated switch.


Clap switch/Sound-activated switch designed around op-amp, flip-flop and popular 555 IC. Switch avoids false triggering by using 2-clap sound. Clapping sound is received by a microphone, the microphone changes the sound wave to electrical wave which is further amplified by op-amp.

555 timer IC acts as mono-stable multi-vibrator then flip-flop changes the state of output relay on every two-clap sound. This can be used to turn ON/OFF lights and fans. Circuit activates upon two-clap sound and stays activated until another sound triggers the circuit.


  • Supply 12V DC @ 60mA
  • On board preset to set the sensitivity
  • On board LED to indicate the Relay on/off state
  • On board Microphone
  • Relay switch 5Amps, 110V-230V



Parts List

image description


10 Response on “Sound Activated Switch – Relay

  1. hello, it has been a good schematic diagram and i tried and worked very well. thanks so interesting and lovely.

  2. I want to use through hole components instead. Of. Surface mount device . So what should I use instead of bc847? ? Plz help.

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