Sound operated Timer

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Sound operated Timer

SKU: Sound operated Timer Categories: ,


Sound operated Timer


          This circuit is based upon NE555 timer and LM324 Quad operational amplifier. This circuit is used in sound based burglar alarm.


  • Output pin 1 of LM324 (IC1) is fed to pin 2 of NE555 (IC2) through capacitor C3. IC2 is configured as a monostable multivibrator. Sound signal, sensed by condenser microphone MIC1 is amplified by IC1.
  • Amplified signal is fed to trigger pin 2 of IC2. Output pin 3 of IC2 goes high and relay RL1 gets energised.
  • Energisation of the relay is indicated by the glowing of LED1. NE555 can source 200mA current; so, an ordinary relay can be directly connected to IC2’s output without an extra transistor driver. Use a good-quality microphone for maximum sensitivity.


  •  Security systems
  • Sound based Burgler alarm

Additional information

Weight 1.000000 kg


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