This project works on the sound of clapping.  If in the night time you want to put OFF your cooler or fan then with the use of this project you can put OFF your cooler or fan simply by clapping with your hand without getting up from your bed.  If again it is required to put ON the cooler or fan then you can do this by simply clapping with hand.  This project can be used for many functions according to the requirement.




This is a wonderful project in the electronic age.  This is a sound operated ON/OFF switch.  Simply by clapping with hands without getting up your seat you can put ON TV, fan or stereo through this project.  When you clap the sound is received by condenser mice and this mice changes sound waves into electrical waves.  The strength of these waves is very weak from condenser mice which can not operate the triac in the circuit.  To increase the strength of these waves, these are amplified through the amplifier circuit made of transistors Q1, Q2 and Q3 [BC547B].


The amplified signal is given to the base of output transistor Q4 [BC547B].  The collector of Q4 [BC547B] gives the amplified signal, which is given to the gate of triac BT136.  It operates the triac and supply is given to the output socket.  The equipment connected with the output socket gets ON.


Through this socket you can put ON your cooler, fan or bulb according to your requirement.  Now if you want to put OFF the equipment running through this socket then by simply clapping you can put OFF the equipment.  The condenser mice receives the clap sound of your hands and equipment is OFF by the relay.  Thus by clapping once the equipment is made ON and by clapping twice the equipment is made OFF.  There is no need to give separate DC supply to the circuit because circuit gets its DC supply from the main AC 230V.



  1. Connect collector, base and emtter terminals of transistor after checking.
  2. Take care that print on PCB does not get shorted while soldering.
  3. Verify the components before starting the job, So that all components are OK.
  4. Take care about cathode and anode terminals of LED before connected it in the circuit.
  5. Use presets of good quality.
  6. Make necessary checking of gate MT1 & MT2 terminal of triac before connecting it in the circuit.
  7. Never touch the components in the circuit while the supply is ON because you can shock from the AC230V supply.
  8. The working voltage of condenser C5 should be 250V.