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4 Tested Clap Switch Circuits

4 Tested Clap Switch Circuits

Want to build a simple clap switch circuit that will toggle any load in response to your claps? The article is presented exactly for this purpose. Here we discuss 4 unique and simple designs which can be selected as per user preference.


The article talks about what the title suggests – a clap switch. A small electronic circuit when built and integrated to any electrical appliance can be made to switch ON/OFF through mere hand clapping.

The entire procedure is explained here in. You have seen magicians doing this, a “clap” and the object vanishes. Obviously I am not here to teach you magic, however the present circuit is nothing less than a magical device, well certainly can be for the children.

The proposed design when integrated to any of your electrical appliance can be used to switch it ON and OFF simply through alternate clapping of your hand. The device becomes more interesting and useful because it does not require any external mechanism or device to carry out the specified operations.

As you must have noticed the clapping of hands creates a loud sound and is sharp enough to move quite a distance. The generated sound is in fact strong ripples or vibrations created due to the sudden compression of air in between our striking palms.

The circuit presented here is basically made up of two stages, the first stage is a two transistor hi-gain amplifier and the second stage consists of an efficient flip/flop.

A mic is connected to the amplifier stage; the sound vibrations made by clapping hits the mic and get converted into tiny electrical vibrations. These electrical pulses are amplified to suitable levels by the transistors and are fed to the flip/flop.

The flip/flop stage alternately switches the output relay driver in response to every subsequent clapping. The load connected to the relay thus also gets activated and deactivated correspondingly.

The circuit may be further understood with the following explanation.

1) Clap Switch Circuit Using IC 741.

clap switch circuit using IC 741 opamp

The above clap operated relay circuit was provided to me by one of the keen readers of this blog Mr. Dathan.

The circuit is very to understand:

The opamp here is configured as a comparator, meaning it is positioned to differentiate the slightest of voltage differences across its two inputs.

When the clap sound hits the mic, a momentary drop of voltage is experienced at pin#2 of the IC, this situation raises the voltage at pin#3 of the IC for that instant.

As we know, with pin#3 at higher potential than pin#2 makes the output of the IC high, the condition puts the output of the IC go high momentarily.

This high response triggers the IC 4017 pin#14, and forces its output to either move from pin#2 to pin#3 or vice versa depending upon the initial situation of the outputs.

The above action switches the load accordingly either to ON or OFF position.

The above 12V clap triggered switch circuit using IC 741 was successfully tried and tested by Mr. Ajay Dussa. The following prototype images for the same were sent by Mr. Ajay.

clap switch tested prototype on breadboard
tested clap switch design on veroboard

The PCB design (track layout) for the above can be seen below, as designed by Mr. Ajay:

clap activated switch circuit PCB track side layout

2) Clap Switch Using Transistors or BJTs

In the above explanations we learned a simple clap activated switch circuit which incorporated an IC for implementing the desired ON/OFF toggling actions. The present design uses a different principle and utilizes only transistors for the above triggering actions.

simple transistorized clap switch circuit

Clap Switch Video Demonstration

Parts List

  • R1 = 5k6
  • R2 = 47k
  • R3 = 3M3
  • R4 = 33K
  • R5 = 330 OHMS
  • R6 = 2K2
  • R7 = 10K
  • R8 = 1K
  • R9, R10 = 10K
  • C1, C4 = 0.22uF
  • C2 = 1uF/25V
  • C3 = 10uF/25V
  • T1, T2, T4 = BC547
  • T3 = BC557
  • All IC diodes = 1N4148
  • Relay diode = 1N4007
  • IC = 4017
  • Relay = 12v / 400 ohms

How it Works

The figure above shows a straight forward two stage sound activated switch.

The first stage comprising T1, T2, and  T3 forms a hi-gain common emitter amplifier configuration.

A mic is connected at the base of T1 via blocking capacitor C1.

Strong sound vibration hitting the mic is instantly picked and converted into tiny electrical pulses.

These are in fact small AC pulses easily make there way through C1 into the base of T1.

This creates a kind of push-pull effect and T1 also conducts in the corresponding way.

However the response of T1 is relatively weak and requires further amplification.

Transistors T2/T3 are introduced exactly for this and help to improve the voltage peaks created by T1 to appreciable levels (almost equal to the supply voltage.)

The above voltage pulse is now ready to be use for toggling the relay ON/OFF and is fed to the relevant stage.

IC 4017 as we all know produces sequential shifting of its output pin-outs (logic high) in response to every positive pulse at its clock input pin 14.

The amplified clap sound voltage pulse is applied to pin 14 of the above IC, this flips the output of the IC to either a logic high or a logic low depending upon the initial status of the relevant pin-out.

This triggered output is appropriately collected at the diode junctions abd used to toggle a relay through a relay driver transistor T4.

The relay contacts ultimately goes to a load or an appliance which is correspondingly switched ON and OFF with every subsequent claps.

Using BJTs and Power Supply

Looking at the circuit diagram we see that the entire circuit has been configured around ordinary general purpose transistors.

The functioning of the circuit may be understood with the following points:

Transformer X1 along with the D1 and the capacitor C4 forms the basic power supply circuit for providing the required power to the circuit.

The first stage which includes R1, C1, R2, R3, R4 and Q1 form the input sensor circuit.

The next corresponding stages consisting of Q2 and C3 form the flip flop stage and makes sure that the signals from the input sensor stage is appropriately converted into alternate toggling of the output.

The output stage consists of a single transistor Q4. It is basically configured as a relay driver stage for translating the alternate ON/OFF actions from the previous stage into physical toggling of the connected load across the relay terminals.

The design is very old, I built it in my school days by assembling a kit. The circuit diagram using transistors is shown in below:

clap switch circuit using transistors with flip flop

Parts List

  • R1 - 15K
  • R2,R5,R12- 2m2
  • R10, R3 -270K
  • R4 - 3K3
  • R6 - 27K
  • R7,R11 - IK5
  • R8,R9 - 10K
  • R13 - 2K2
  • C3, C1 - 10KPF Disc
  • C2,3 - 47KPF Disc.:
  • C4 - 1000uF/16V;
  • Q1,2,3,4 - BC547B
  • D1 - 1N4007
  • D2,3,4,5 -1N4148 _
  • Xl - 12V/300mA Transformer .
  • MIC - Condenscr Mic
  • RLY — 12V Single Charge over relay

Another version of the above can be seen in the following diagram:

solid state clap switch circuit with lamp

3) Double Clap-Clap Switch Circuit

All the clap on switch circuits explained above have the ability to operate only with single alternate clap sounds. This feature makes the circuit vulnerable to external sounds which might occur occasionally triggering the connected load with the circuit.

A double clap operated circuit thus becomes more suitable and resistant to spurious triggering due to the fact that it would toggle only in response to two subsequent clap sounds instead of one.

The explained circuit is simple yet effective and does not employ microntrollers for the implementation unlike other circuits on the net.

The circuit has been tested by me, but it is a fairly complex design it's important to first understand the stages convincingly, and then build it to avoid failures.

Circuit Operation

The proposed clap-clap circuit or double clap circuit functioning may be understood with the following points:

The lower stage is basically a simple sound activated switch circuit which would activate with any loud sound.

The IC 741 is rigged like a comparator with its pin#2 referenced at some optimal fixed potential determined by  the setting of the given preset VR1.

Pin#3 of the IC becomes the sensing input of the IC and is connected with a sensitive mic.

The adjoining IC 4017 is a bistable stage which activates the connected relay driver stage and the load alternately in response to every positive high pulse at its pin#14.

When  a loud sound such as a "clap" hits the mic, it momentarily grounds pin#2 of the IC741 resulting in a momentary high pulse at its pin#6.

If we connected this output to pin#14 of IC4017 would have resulted in an instant toggling of the load with every single sound input which we don't want here to happen, therefore the response at pin#6 of  IC741 is broken and diverted to an IC 555 monostable stage.

How IC 555 is Configured

The IC 555 circuit is rigged in such a way that when its pin#2 is grounded, its output pin#3 becomes momentarily high for some period of time depending upon the values of the 10uF capacitor.

When a sound hits the mic, the high pulse from IC741 output triggers the BC547 attached to pin2 of IC555 which momentarily grounds pin#2 of IC555, which in turn put its pin#3 high.

However the instantaneous high at pin#3 of IC555 takes a while to reach the connected BC547 due to the presence of the 33uF capacitor.

By the time the 33uF charges and switches ON the transistor, the potential at the collector of the transistor is already gone due the absence of the clap sound which happens only momentarily.

However with the application of the immediate subsequent clap provides the required potential at the collector of the transistor which is now allowed to the reach pin#14 of the IC 4017.

Once this happens the relay driver triggers or deactivates depending upon its initial condition.

The toggling of the load thus takes place only in response to a pair of clap of sounds making the circuit reasonably foolpoof.

double clap clap activated switch circuit

About the Author

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials. If you have any circuit related query, you may interact through comments, I'll be most happy to help!

150 thoughts on “4 Tested Clap Switch Circuits”

  1. Hi there
    I could not find a bc547 in the market
    i know its very common..its strange it wasnt available
    anyway what is the best sub for it? i have plastic 2n2222 , bc546, bc 548 and bc 549
    among these which one do u suggest?

    • in reply to “Both will work, you can use any one of them”

      yes but which one would u suggest?a 2.2k pot or a 4.7k pot?

      • There will be no noticeable difference in the response, so I don’t have any specific suggestion, you can use the one which is available with you.

  2. the second circuit as you said has more sensitivity. but i cant see a pot on it
    i wish there was a pot so that we could adjust the sensitivity

  3. Hi.I want to make the first circuit
    To get more safety Im planning to use a fuse for my 9v 300mA power supply.what fuse amperage do I need? 0.5a fuse or 0.3 or…? can I even use 1.6A fuse? will it cut the AC if the power supply is shortened?

    • Hi, a fuse is actually not required, and the chance of your power supply getting shorted is almost zero. Still if you are interested you can put one on the AC side of the power supply, the rating will depend on the load or appliance that you connect with the relay contacts. If it’s a 0.5 amp lamp then the fuse could be rated at 1 amp and so on.

  4. hi sir…i really like your website
    i always come here for %100 working circuits
    i have a question about the circuit above
    the first circuit
    what is a good replacement for the 741 ic
    i have TL081, TL061,TL071
    Ive heard that the TL071 opamp is a low noise amp which i think does affect the circuit’s sensitivity right? but i dont know for sure if it can be replaced with 741 with no problem
    the reason im looking for a replacement is i could not find a 741 ic at store

    • Thanks oppa, I,m glad you liked my site!

      You can actually use any op amp for this application. The low noise characteristic is not relevant to this application, since it is used only as a basic comparator, so basically you can use any op amp here, all will work

      • hello sir
        i am very interested in this project
        i want to make this circuit for my bedroom light…can u plz tell me which circuit has more range and sensitivity?
        and about the second circuit…can i supply it with 9 volt power supply and replace the 12v relay with a 9v one?
        the 4th circuit looks nice.. does it work properly? no offence…in my country these components are expensive

        • Thanks Hobbyman,

          The second circuit seems to have the longest range and high sensitivity. Yes it can be used with a 9V power supply and relay.

          The 4rth circuit is yet to be tested but I am sure it will work once everything is adjusted perfectly.

  5. hai Iam vishnu, sir I bulid a clap circuit using Bc547transistors without any Ic their are 3 transistor of Bc 547 and1transistor BAc368 without relay my circuit is completely worked first after some type it is not detect sound instead when we touch mic the LED wil ON&OFF .

    • Vishnu, if you have built it on a breadboard then possibly there could be a loose contact somewhere, otherwise one of your transistors could have gone bad…BC547 are rated at minimum 60V so those may be fine but BC368 is rated at 20V only so may be you could test this transistor….and if you are using a relay make sure to use a freewheeling diode across the relay coil

  6. I tried doing this project in breadboard but it doesn’t respond to my clap or any sound i made. the LED only lit, that’s it. what can be the possible problem in this one? I hope i could get a quick response, it is for our electronics project. Thank you and good day!

    • first of all recheck all the connections, because breadboard are always prone to mistakes and loose connections.

      if possible remake it on a veroboard by practical soldering.

      If you are referring to the last circuit, remember the preset has to be adjusted carefully to get the results, otherwise the circuit won’t respond.

      for testing the IC 741 response, remove the LED/resistor from the IC 4017 pin#3 and connect it across pin#6/ground of the IC 741.
      Now after careful adjustment of the preset you should be able to see this LED becoming momentarily ON on each clap sounds.

  7. YES IT WORKED,after a long time.Thank u for your instant reply.It is only because of your fast reply i could make it successfully.Now i have to make another project-amplifier circuit.Please suggest any website for this project which uses an ic,condenser mic and a 8ohm speaker(or any small speaker).

  8. I made it but when i connect the power supply,8050transistor near the diodes is getting heated and the circuit is not working.Please tell me where is the problem in my circuit.I have used the first circuit.

    • In the first circuit it's BC547 near the relay, anyway even if 8050 is used it should not become hot…unless the relay coil is shorted, or you have done something seriously wrong with the connections.

      make sure you have connected the transistor pinouts correctly.

  9. sir, as u said to connect 10k at pin 4 n 15 of ic 4017 and capacitor to pin 15 and +vcc .
    the circuit work correctly as led at pin no 3 of ic 4017 glow before clap and after clap the led connected to transistor glow, but this happen only one time, after that circuit stop working none of led glow, now what should i do?

    • Prashant, you can try putting a resistor 10K in series between pin#6 of IC 741 and pin#14 of IC4017, and connect a 1uF/25V capacitor across pin#14 and ground.

      also for better reliability configure the output of the 4017 exactly as done in the first diagram.

  10. Sir can you tell me that can we use this circuit to automatically open and close the door??? Please reply as soon as possible.
    If yes then how?? What changes should be made in the circuit??? I have to submit a project proposal and my project is "automatic door opening using clap switch" and the circuit should work from the minimum distance of 8 feet.
    Please help me…!!!!
    The door is not of the full size. There is a mechanical model of wood of almost 1 feet tall.

  11. sir, when i apply 9v to the circuit which led sholud glow by default i.e.before clap, the one which is connected to pin no3 of ic 4017 or the led connected to transistor

    • pin#3 LED should light up… but sometimes it might not because the logic high might disappear across one of the other outputs of the IC 4017….so to prevent this please connect a 10K resistor between pin#15 and pin#4…and also connect a 0.22uF capacitor from pin#15 to the positive rail.

  12. sir any minor changes can made to second circuit that lead to more sensitive and responce small sound genarated by clap. now I was still struggling to adjust 1k preset as you said above. thanks

    • you can try connecting a small value capacitor across pin6 ans pin3….this should improve the sensitivity of the circuit manyfolds

      still the 1K perset adjustment will be crucial.

    • sir i bought 0.22uf capacitor but it has polarity then which side to connect #pin 3 and #pin 6 ( #pin 3 positive and #pin 6 negetive . may i correct)
      and was this 0.22uf capacitor to connect IC 741

    • Manjunath, you can connect positive to pin6 and negative to pin3, but a non-polar would have worked better…I thought you would bring a ceramic disc type capacitor.

    • sir sorry to say that, i connected non-polar 0.22uf to the ic741 . but it was still not working perfectly even though i adujust 1k . which stage may be faulty as per your knowladge thank you very much sir

    • can't say exactly, your MIC could be faulty or assembled with wrong polarity or the IC may be faulty or with wrong connections…
      when you clap the MIC grounds the pin2 of the IC momentarily which causes the pin3 and pin6 to go high, this the basic working principle of the circuit, you can confirm whether this is happening or not.


    • Manjunath, you will need to adjust the 1K preset precisely for getting a proper response from the cirucit.

      Initially, make sure the output of the IC just merely turns "low" (0V), by adjusting the 1K preset.

      Thia will set-up the circuit optimally and claps from a little distance will also become responsive

      this circuit is better than the first one.

  14. Sir in second diagram where to connect VR1 as it contains 3 pins (the printed side facing us right side pin is negative, center pin is out, and right side is positive.) as per your diagram two pins are connected. Please help regarding this thank you.

    • Manjunath, VR1 here should be a preset not a pot, and by the way presets and pots do not have polarity, so the orientation is not critical.

      you can use the center pin and any one of the outer pins, and leave the other pin free (unused)

    • LED is used for indicating the clap response, it cannot e replaced by anyuthing else.

      the relay is for switching a load ON/OFF in response to the claps…

  15. Hi swagatam ,I made a clap switch it's different from what you have posted here but works the same way. I want to Decrease it's sensitivity to make it a bit practical.

    I was wondering if I could add a pot in series with the mic,will it help ?

    • Hi Shirish, yes you can put a pot or a preset in series with "R1" and adjust it appropriately for the required level of sensitivity.

  16. Dear sir,
    I tried out the clap switch which turns on for two claps as suggested by you. But it is not working. Could you please tell me what's the problem?

  17. Hello, I would like to use this circuit as a school project (toy car) using a 9v battery. How do I exactly do that and also, I already bought all the parts and a 9V motor and a 9V battery

  18. Hey, iam from indonesian, i want to ask question, look over the PCB according to the first pat sensor circuit or the second ? ( clap simple switch that was given to me by one of the readers of this blog Mr. Dathan sharp . )

  19. Hello Mr.Swagatam ……I have a minor problem…i made mr.ajay's circuit….but the problem is the sensitivity of the mic….the sensitivity of the mic is very low…it doesn't even responds from 0.5 feet…plzz tell how could i increase the range of mic to the extreme level….. i will be thankful for your quick reply…

    • hello harishwar, try a 10k preset in place of the shown 1K, and adjust it carefully to achieve the required sensitivity….hopefully this should solve the issue, other wise we may have to seek other options.

  20. hello Mr. Swagatam Majumdar……

    plzz sort out my problem as soon as possible…..
    i made mr.ajay's circuit …it works perfectly but the main problem is the sensitivity of the mic….plzz tell how can i increase the range of mic to the extreme level…. i need the mic to work at least at the range of 5m….if its not possible…what is the maximum range of the mic….waht modifications should i do in the circuit…. plzz reply

    • no, not the whole circuit, replicate only the diode section which are connected to pins 2,7,1,6,11 of the IC4017, make sure that now pin15 is connected to ground.

    • connect one LED in series with R4 also and check its response, if this LEd lights up very brightly will ensure a proper functioning of the 741 section….then you can only replace the 4017 IC and recheck.

  21. nope it doesen't work. i mean the relay doesent turn on. However i measure the voltage between the colector and the postivie voltage supply and it;s about 3V volt's.

    • it means your IC 4017 is not responding, may be it's faulty, put diodes at the output of the 4017 as shown in the first diagram and do the connections accordingly for the relay and the transistor also…..try it before discarding the IC.

    • Iave placed the capacitor and it it's working better but not like it's suposed to. Sometimes it just starts to blink and it doesen't stop and when i place the relay it just turns off. I have relapced the cd4017 chip with another and insead of a pot i used a 1kohm resistor which i now replaced with a 470ohm resistor and now it's just worse.

    • the pot is required so that the sensitivity and optimal working from the IC741 can be adjusted and ensured, if you remove it you would be unable to do the above settings

      the 4017 seems to be not functioning correctly…you may need to check it separately.

      break the link between pin6 of 741 IC and pin14 of 4017 but do not remove R4 and the parallel capacitor from pin14.

      Now manually touch pin14 to positive with a piece of wire, the relay should respond with an alternate ON/OFF sequence..this would confirm a good 4017 otherwise some other fault could be suspected.

    • yes MIC has a polarity, check its pins, the one which is isolated from the body ground track is the positive and will go to the IC input pin2, relay voltage must be equal to the supply voltage

  22. hello sir,
    I make second circuit as shown by the circuit diagram, only Red LED glow. I didn't understand the reason.
    Is there any specification of mic.
    Plz help me im very thankful to u

    • Hello Mahesh,
      connect another led in series with R4, now adjust the preset carefully until it just shuts off…now clap in front of the MIC, the circuit should respond as proposed, and this LEd will momentarily flash and again shut off.

  23. hello sir i want 2 make a clap switch for my requirement but how can i use it for a dc supply.what changes to be made for the above circuit to use it in dc supply. i will thank full to u if u suggest me

  24. dear sir,
    i m a student. my teacher has gave me this model
    will u please give a easy stepwise note that how can i make this………
    plzzzz sir……

  25. I have assembled the board for an extra credit project for an engineering physics class however it is not working. When I connect power to the circuit I'm getting a random array of lights either one or two and clapping has no effect on the system, any ideas what could have caused this? I have checked and rechecked and the diagram has a few mislabeled items such as two R5's and no R3. Please help me thank you very much.

    • The circuit could need some fine tuning and tweaking before it produces the intended results.

      You can try the following few thing's:
      decrease R1 to 2.2k or to any smaller value
      remove C3 from its shown position and place it in parallel to the collector resistor of the BC557,
      use BC547 for T1.

      I'll correct the mislabeled pats quickly…

      By the way there are no lights in the circuit??

  26. Please, I have no access to IC741. Can I connect the amplification stage of diagram 1 to the 4017 flip flop configuration of diagram 2……. Merry xmas

  27. below circuit published by u does not work when i clap nothing happens i have checked my all connections twice only the red LED glows

  28. Sir.! I want to make a circuit about voice interrupt music..this circuit consists of two input, audio input and mic, and one output to amplifier. First, the input from any audio player. While playing, if their is any sound into microphone, audio will become mute. After the sound from microphone is stop, the audio will be increasing its volume rapidly to its initial volume for some seconds. So, can you guide me some sir?

  29. Hi, I am doing this for a project in my electronics class at school I have breadboarded the circuit exactly as above but nothing happens when I clap. I replaced the microphone with a switch to test also but that didn't work either. Can you please help me find the problem?

  30. Sir! I wonder one point sir..does this circuit active only with clap sound? And about other sound like speech sound? What happen when there are alot sound in that place?

  31. In the above article "Make a Simple Electronic Clap Switch Circuit", only one 230V supply line will pass through the circuit, right? And the other will directly go to the load?
    If yes, where do I exactly connect the two wires in the circuit, the first one coming from the supply line and the second one going to the load ( I can't understand that from the diagram)
    As I am an amateur, any help will be greatly appreciated.

  32. hi my name is jaco.
    i have a electronic project where im required to build a clap switch using the following componets:
    33 k ohm 1/4 W 5%
    1 M ohm 1/4 W 5%
    5 K 6 ohm 1/4 W 5%
    270 ohm 1/4 W 5%
    47 k ohm 1/4 W 5%
    BC 547
    100 uF 16 volt redail
    10 uF 16 volt redail
    1 uF 16 volt redail
    1N4148 diode
    5mm LED (red or green)
    electret microphone
    6 V DC PSU
    could yo please explain how to connect the circuit. this is my first time.

  33. Dear Swagatam i will be sending you a circuit diagram in mail. kindly verify and tell weather it can work properly or not??

  34. Dear Swagatam

    I know of this circuit and i want to the rf portion form this circuits and incorporate it with HT640 and HT648l so can i do that and if possible then what changes have to be made in the circuit???

  35. Dear Swagatam I am in need of RF receiver transmitter circuit compatible with HT640 and HT648L. I want to make the circuit on my own so dont want the readymade available in market

    • Dear Swagatam

      I already know about this readymade RX-433 and TX-433 but i want to make circuits on my own so don't want to use this readymade ones. can we use the receiver transmitter circuit that is used with TX-2b and RX-2b???

    • I didnt get your point. I want to make circuit 8 chanel transmission so i am using ht640 and ht648l for this purpose. its just for remotely controlling 4 motors. i am planing to use two L293d at the output bits of ht648l

    • I responded to your previous comment where you mentioned TX2b and Rx2b chips. These chips require RF stages for operating an RC model

    • Dear Swagatam you asked that what will i insert in RF stage so didnt get this question of yours and i have circuit regarding this rf stage can u help me evaluate it, if yes then i can sent you the images on your email id.

    • Dear kkaranjia,

      I was referring to the following circuits:


      anyway you can send it to my email ID.

  36. Dear Swagatam,

    Can You help me with RF receiver transmitter circuit which is compatible HT640 and HT648L. And I don't want the readymade circuit which is available, I want to make my own so please provide circuit if possible.

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