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Simple Clap Switch Circuit Using Transistors

In one of my earlier post we learned a simple clap switch circuit which incorporated an IC for implementing the desired flip flop actions. The present design uses a different principle and utilizes only transistors for the above triggering actions.

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 flip flop actions from the previous stage into physical toggling of the connected load across the relay terminals.
The diagram of a simple clap switch circuit using transistors is shown in the below given diagram

Parts List

R1 - 15K
R2,5,12- 2m2
R R3 -270K
R4 - 3K3
R6 - 27K
R7,11 - IK5
R8,9 - 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:

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    1. Hi Swagatam my name is Riyad.

      i would like to ask you if you could maybe help me with something. I am using an existing single clap switch circuit for a project design for University but i want to change the single clap operation to a double clap one using flip flops or something like that but not a microcontroller, but i have no idea how to incorporate that into my circuit. Could you help me please? My personal email is Thank You

      1. Hi Riyad,

        I'll do it for you, but in return you will have to do me a favor.

        Write a min. 300 word post, in your own words about your above requirement and send it to me.

        You can stuff as many words as you like about your requirement, about your experience in the field, etc etc.

        i'll publish this data in the form of a new article and also provide the circuit diagram in it.

        You can send it to


    2. The circuit is not working for me properly. O/P is always on irrespective of Clap signals. Plz help

      1. The circuit was built by me a long time ago when I was in school, it had worked perfectly without any issues. Actually it's a Vega-kit project which I have produced here.

        Please check all the connections properly, the upper terminal of C3 connects with D3 and R12 only.

        R9 is connected across base of Q2 and the collector of Q3.

        Only the black dots indicate connections.


    3. Instead of TRANSFORMER,can we supply the power via 9 volt battery???
      please reply soon.

    4. Hi me Niladri..
      i am a fan of u....
      i want to make a clap switch which will operate on 220 ac line....
      pls hlp me...
      how can i connect this with main line to operate bulb tubes and other electronic apps.
      and pls sujjest me also which circuit will cost low as much as possible...

      1. You can try the second circuit shown in this article:

        Do it only if you are equipped with the all the basics of electronics.

    5. Hi i m Apurv
      Can u provide full and final report file of the first circuit for my class 12th CBSE project
      I hav made the Project (materials readily available just assembled)

    6. my circuit is not working .plz define which component is disturbing.

    7. plz help me circuit is not working

      1. everything's correct in the shown diagrams, I have myself tested the first one and it worked at the first attempt, it would be difficult to troubleshoot your circuit without practically examining it.

    8. My circuit is not working . Please provide me how to start check for falt . As I turn on the ac mains I fell somthing like vibration in transformer but by clapping its not working.

      1. you might have done something wrong in the connections.

        note that R7 and R11 upper ends are connecting only the positive line.

        Q3 base is connecting with only R8

        the crossing lines which are not shown with black dot are not connecting with each other

    9. Is there positive negetive in condenser Mike

      1. is there is....see the back PCB side of the mic, the pin which is connected with the body of the mic via PCB track will be the negative pin.


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