555 Timer Police Siren Circuit

admin June 11, 2010 5 Comments

Circuit Description

Police siren circuit given here is a circuit based on NE 555 timer IC. This circuit uses two NE 555 ICs (IC1 and IC2) and which are the core working parts of this circuit. Here two timer ICs are wired to work as astable multivibrators. But these two timer ICs are working at different frequencies. IC1 is slow astable multivibrator operating at a frequency of 20Hz and a duty cycle of 50% whereas IC2 works at 600Hz as fast astable multivibrator. The output of IC1 is fed to the control pin (pin5) of IC2. By this connection, the output frequency of IC2 will be modulated with the output frequency of IC1.

The circuit can be powered from a DC supply voltage ranging between 6V and 15V. Power supply used here is 12V DC supply. The loudness of output can be further increased by inserting a power amplifier circuit at the output stage of this circuit.

Circuit Diagram

555 Timer Police Siren Circuit

555 Timer Police Siren Circuit


  • Use a Perf board to assemble this circuit.
  • The output frequency of IC2 is controlled by the output of IC1.
  • One NE 556 IC can be used instead of two NE 555 ICs.

Use speaker with rating 64 ohm, 500mW.

  • July 18, 2010

    Any time a 555 can be employed to generate sound, I really enjoy it.

    Thank You,

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  • July 22, 2010

    555 Timer Police Siren Circuit…

    Police siren circuit given here is a circuit based on NE 555 timer IC……

  • preyen
    January 23, 2011

    why is the diode and resistors used?

  • February 23, 2011

    You made some clear points there. I looked on the internet for the topic and found most persons will approve with your site.

  • เสื้อผ้าแฟชั่นรา?…

    555 Timer Police Siren Circuit…

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