Clap Switch Circuit using NE555 timer IC

Here is one of the interesting 555 timer circuits to trick your friends while studying electronics in schools. Clap switch circuit is the local name of sound controlled flip flops. This sound controlled light can also be used as sound detection sensors. Flip flops are single bit storage elements. NE555 timer IC is the important part of this circuit. Here NE555 is configured in monostable multivibrator mode and is connected to the clock input of a 7474 D flip flop. The flip flop is connected to work in ‘Toggle’ mode. The relay circuit is energized by a 7474 flip flop. You can connect any electrical/electronic device at the output instead of the electrical bulb used here. Below is the electronic circuit diagram and working of the clap light switch.

Electronic circuit diagram of Clap switch

Clap Switch Circuit Diagram
Click on the image to Enlarge

Components Required

  1. Power supply
  2. Condenser Mic
  3. Resistors (10KΩ, 1MΩ, 2.2KΩ, 220KΩ, 100Ω)
  4. Capacitors (0.1μF, 1μF)
  5. Transistors (BC 548, BC 187)
  6. NE 555 IC 7474
  7. 6V or 12V Relay (According to Vcc)

NB: This circuit will work with 6V as well as 12V. So you can select transformer rating 230V-6V or 230V-12V

Working of Clap Switch Circuit

  • Here the 555 IC operates in monostable multivibrator mode. It can be triggered with a low voltage at the 2nd pin.
  • The collector voltage of BC 548 is connected to the trigger pin of 555.
  • High amplitude sound signal in front of the condenser mic, turns ON the transistor BC 548.
  • Then its collector voltage falls to low, and the 555 turns ON for a time 1.1RC sec.
  • Output of the 555 is connected to clock input of D-flip flop (IC 7474). It is a -ve edge triggered flip flop. When the Monostable output goes to zero, flop-flop’s output Toggles.

The D-flip flop works as follows 

  • Its output will be the input only after a clock pulse. Without the clock, output will be the same i.e. it will not affects the inputs.
  • When Q’ is connected to the D input, (say Q’=1) for the 1st clock pulse, Q=1 & Q’=0, for the next clock pulse Q=0 & Q’=1.
  • That is (For time being consider flip-flop out is zero), for the 1st -ve transition output of the flip-flop goes to high and for the next -ve edge, output will be low. It will continue for successive -ve edges
  • In this way we can hold the output as low or high.
  • The flip flop out is connected to a relay, when the output of flip flop is high it will energize the relay coil.
  • So the bulb connected on the relay will light up/down with each clap or any sound.

Components Pinout

555 Timer IC Pinout7474 IC Pinout
Pinout of BC 548Pinout of BC 187
Capacitor Pin configuration12V Relay Pin configuration

51 thoughts on “Clap Switch Circuit using NE555 timer IC

    • Hello Govind, Welcome to i-St@r Technologies Lmtd. I didn't get you please explain detail. i-St@r group can support you in every electronic aspects.

  1. i make this circuit but it does n’t work transistor bc548 is getting very hot after few sec so can u plz help me to recognize the problem in my circuit

    • Hi akshay jha,

      Check if the pins of BC548 connected is correct, refer the pin diagram of BC548. Also check the transistor is damaged or not, connection error may damage transistor.

    • Hi Mtatiro,
      Yes, it is 100% free from false triggering. If your circuit getting false trigger there may be 3 reasons.
      1. Your power supply don’t have voltage regulator IC.
      Recommendation: Please use pure DC power source as Vcc instead of simple Bridge rectifier circuit. The circuit is shown here Regulated lab power supply circuit
      2. Sensitivity of Mic is so fine. Your Mic may sensitive to very small noise and sounds.
      Recommendation: Try to change Mic and test circuit with another Mic
      3. Without Free wheeling diode. The diode connected at Relay called Free wheeling diode, has very importance in the case of blocking switching transients. May be you didn’t connected the Diode or the diode may defective.
      Recommendation: Check the diode is OK with the help of multimeter.

      I suggest these steps to follow. Let me know your progress. Good luck!

  2. Hai admin I can’t understand this relay how can I connect the wires what is nc and no there is 1and 2 com

    ex.u can show me r where could I connect the wires for dc to ac in realy thanq admin im happy that u r helping us god bless u

  3. hello, is bc187 needed? can it be two bc548’s? I cannot find bc187 where i am, is there a suitable replacement for it?

  4. Hlo admin plz upload the circuit diagram for small LEDs without using relay. and i also have confusion on the diode connected parallel to relay

  5. IC 7474 = CD4013 ???

    I don’t find IC7474, But found CD4013 which is dual D flip-flop is a monolithic complementary MOS (CMOS) integrated circuit constructed with N- and P-channel enhancement mode transistors.

    Plz answer?

  6. Hi,

    I am not able to find IC 7474, is it possible to use any other instead of this ?
    Somewhere I saw a clap switch circuit with 2 NE555, but as per the comments from different users the mic sensitivity is very low you have to clap hard and near to mic to operate it. Just want to know the sensitivity of your switch and do you have any good clap switch circuit with 2 NE 555 as I have 555 but not 7474


  7. Sir your website is great. Can you guide me to make this circuit by using ic cd4013. because ic7474 is not available where I live. Reply pls….

  8. Sir I have a small doubt…does the circuit work on external notice other than the sound produced by clapping. If so then how to make it response to clap sound only.

  9. yeah it worked… but please attach 0.1 microfarad capacitor at pin 5 of ne555 and capacitors second terminal to ground.!! THEN CHECK THE OuTPUT AT pin 5 of d flip flop …IT WORKS

  10. thanks alot it helped me alot…but i have i doubt i just want to know that ic555 timer is a monostable or bistable..and can u please tell me how will be the block diagram of this circuit…

  11. I have connected all the components correctly but it does not work…please help me…is it possible to check the mic?

  12. My circuit does not work!I think the problem is in condenser mic..What should i do?Is there any way to check the mic?

  13. Wher cn i find a condesor mic using proteus software…. Some said i shuld use a signal generator bt still d circuit is not runni what could be the proble?

  14. Hai, the circuit is working, thank you all. But I like to make it more sensitive to sound. Because now I have to give the clap more closer to the mike to make it work. What should I do?

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