Here is a simple circuit diagram of a simple musical horn using two NE555 ICs. Two ICs are wired as astable mutivibrators. The output of first multivibrator is given to the discharge (pin 7) of the second astable multivibrator. The combined effect of the astable multivibrators produces a musical tone at the output.

 Circuit diagram with Parts list.



  • The sound effect can be adjusted by varying the POTs R2&R5.
  • The speaker can be a 8 Ohm tweeter.
  • The circuit can be powered from a 9V PP3 battery.
  • The ICs must be mounted on holders.
  •  All capacitors must be rated 15V.


  1. V.Ramakrishnan

    The sound generated by this circuit at 9 Volt supply is very feeble. How to increase its sound .Is it possible with a single transistor based amplifier ? If so please help me to have such a circuit at the output of 2nd 555 IC instead of feeding a loud speaker. hope I will receive your reply in tis. Kindly help.

  2. V.Ramakrishnan

    I have assembled this circuit on a bread board first in which I could get only clicking sound then I have soldered the circuit in a general purpose pcb and the circuit functioning real train horn. I have used one 8 ohms tweeter and another one from a broken toy. The sound from 8 ohms 2 inch speaker was not that much appealing whereas the sound from the speaker of toy ca with funnel attached has produced real sound of a train horn. Thanks for such a circuit. If I get pcb for this from you I am ready to buy a minimum of 10 nos. a line from you will be appreciated

  3. malith prabudda

    please send me sound of this circuit

  4. Jbuddyman

    I’ve tried to build this circuit, but have failed. When I powered it on, it sounded a bit then stopped working all together. I built this on a breadboard. I noticed that it requires holders. But holders are used when you either need to easily switch the chip out or want to prevent heating the chip when soldering. Do you need a holder for the 2 ics even when mounting on a breadboard? If not then what did I do wrong? Thanks to anybody who answers

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  6. Sheikh Hassam

    Hi sir,
    I am working on clap switch circuit and circuit competition will be on 15 April.
    Specifications are
    “make clap switch circuit using 741 with 9v battery which activates on clap sound.the circuit which detect the faintest clap will be may use other ICC’s along with 741.

  7. I need more description of this musical horn project….will u b able to snd it to me???

  8. hello Seetharaman,

    I have forwarded my email ID,

    thanks for all ur help.

  9. Hello seetharaman,

    I didnt know where to address it, hence i picked this aritcle.

    Is there a circuit diagram for clap switch activated LED (Preferably 20-30LEDS) mains opreated

    Thanks for all your Advice.

  10. Seetharaman

    Hi Zohaib lots of circuits have appeared in Circuits today, you can use one of them or kindly post your requirement

  11. srinu RCEE eluru

    hiiiiiiiiiiiiiiiiiiii circuit working very nice thankyou

  12. jahidul hasan rashed

    hi,i am from bangladesh,want a simple and easy mp3 circuit diagram include fm radio,for hobby,which will make easy in home…………..

  13. Can anyone please design a circuit to supply 6v on a clap i.e a clap activated 6v power supply.
    6v output should be continues and show proper relay connections

  14. very good one ,sir
    i m one student of tech in my

    anmar ,asia

    i interest more on wireless control n robot tech