How to Make a CLAP ON - CLAP OFF Circuit From Scratch - No Software Required

Introduction: How to Make a CLAP ON - CLAP OFF Circuit From Scratch - No Software Required

Hi there! My name is Patrick, and I am an electronics engineering technician who works full time ...

Hi all
This video is a very detailed tutorial about how to make a clap-on, clap-off toggler circuit that can either light up an LED, or turn a 5v relay on and off.  It is inexpensive, and easy to build.  The parts are less than $15 if purchased off of ebay.  You don't need to use all of this hardware.  You can use some of the electronic bricks talked about in the video to modify your own circuit.  This is a hardware based circuit, and it requires no software at all.  I'll be making other tutorials in the upcoming weeks.  I hope you enjoy this video.  It is long, but very detailed! 

In the video, I talk about the following electronic bricks, and I assemble and test as the video processes:
1) The microphone ciruit
2) The amplifier stage (To amplify the audio signal from the microphone)
3) The comparator stage (To create digital square wave)
4) The re-triggerable Monostable multivibrator stage (To turn hundreds of pulses into one single long pulse)
5) The toggler stage (Based on a JK flip-flop circuit)
6) The relay stage (To control AC devices)

I've created two other instructables on clap on/off circuits that rid the need of lots of hardware by using a programmed chip to do all the work.  They can be found here:

If you have any questions, I'll be more than happy to answer them.  If you have the parts, just follow along with the video, and you'll be able to re-create the circuit exactly.  Remember, the parts can all be found through ebay.    Thanks for watching, everyone!



    • Metalworking Contest

      Metalworking Contest
    • Fix It! Contest

      Fix It! Contest
    • Water Contest

      Water Contest

    33 Discussions

    Great circuit. It operates correctly other than one problem: Instead of
    an output of 5 volts, I only get an output of 3.23 volts at pin 6 of the
    LS109. It will not trip my relay. The LS109 has 5 volts going into it
    at pins 1,2, and 5. #4 has 108mv input.What am I doing wrong? Thank you.

    Do you have any ideas on how I could make a sensor to pick up inaudible tones in an audio file which could be used to turn on/off specific puppet stages lights? I used to work in radio and we used tertiary cue tones on tape to trigger the next cart machine to play the next song or jingle or commercial. See for more information on what I am talking about.

    Great Job!

    Your video was clear and easy to follow.

    You helped me out a lot.

    Thanks again!

    1 reply

    I searched on the web how to use it so I connected the pins on the right way and it works :) thank ylu

    Sorry guys. The 74LS123 has 16 pins. Not 14 pins. There pinout in the datasheet shows inputs/outputs for 1 and 2, as there are two on chip monostable multivibrators. Just use what I mentioned in the video, and ignore any pin that has a 2 in front of it.

    Might want to change this statement: "This is a hardware based circuit, and it requires no hardware at all".

    3 replies

    Boh! That was dumb of me. Thanks for bringing that to my attention! I'll fix it right away!

    Hi, thanks for the video, but i noticed that the 74ls123 have 16 pins and you say that it have 14 pins What can i do with that? thank you

    Hi I noticed the same about 74ls123 do you find any solution about that? Thank you

    hi, we were trying to implement this circuit, but the output was opposite to what we expected. The LED was ON throughout and when we clap it went off for a few seconds, after which it was ON again. Is it because a monoshot is triggered when the input is low? Could you please suggest a way to correct it? Thanks in advance :)


    Why do you have to use so many parts?
    Why not use one Common emitter transistor for amplification
    Fed to the trigger of a 555 timer for multistable multivibrator
    and one T Flip Flop

    This is a great tutorial...We had a great time watching it...Thank you so much! :)

    i'll like to ask what is the use or application of this clap off clap on circuit?

    Fantastic job with the tutorial - keep them coming, please. Just made the circuit. I tested it with a PowerTail II switch (not UL listed either, btw) hooked to a lamp, since I'm leary of mixing high voltage and low voltage. I was able to drive that relay without the transistor. It took 16 mA when not connected; 22 mA when driving the relay. Too high of current consumption for battery power. Going to try the other clapper circuits now. Thanks again.

    This is awesome. Thanks Engineering Shock! No real prior experience, but after following you're tutorial and reading all the spec sheets I feel like a pro.

    I hooked up the second one-shot included in the 74LS123N package after the first one to get a delayed pulse. Then I ANDed the two one shots and sent the result to the flip flop and now I've got a CLAP CLAP ON - CLAP CLAP OFF circuit :).

    You video tutorials are top draw. Keep em coming.



    can we use 74LS123D instead of 74LS123A monostable multivibrator,if yes please tell me its pin configuration.I cant get the output. please reply as soon as possible.

    this is great! just one question is it posible to add diferent output no just on/off
    for example if the output is 10v, is it possible to have 10, 5, 2.5 and 0v instead ?