Police Siren Circuit Using 555 Timer IC


In this tutorial, we will learn how to create a Police Siren Circuit Using 555 Timer IC and a few other electronic components. This circuit allows for a smooth transition between two different tones or frequencies, similar to the sound emitted by police cars. By following this guide, you can create your own police siren circuit and even combine it with a police lights circuit for a complete emergency vehicle simulation.

Hardware Required:

2×555 Timer IC
1×8Ω Speaker
×Resistors: 100K, 33K, 2 x 1K, 2 x 10K
×Capacitors: 1000uF, 100uF, 10uF, 100nF
1xFew Breadboard Connectors
1x(5-9)V Power Supply

Circuit Diagram:

Police Siren Circuit Using 555 Timer IC

How This Circuit Works:

To understand how this police siren circuit works, let’s first recall the electronic piano circuit we built in a previous project. In that project, we used different resistor combinations to generate various output tones. This concept forms the basis for our police siren circuit. In our Police Siren Circuit Using 555 Timer IC, we utilize the astable mode of a 555 timer IC to produce a single tone. However, to mimic the sound of a police siren, we need to transition between two tones or frequencies.

To achieve this, we introduce a second 555 timer IC in astable mode and connect its output to the control pin of the first 555 timer IC. Depending on the output state of the first 555 timer IC, we obtain two different frequencies from the second 555 timer IC. The presence of a 1000uF capacitor ensures that the voltage at the control pin increases and decreases gradually instead of experiencing sharp rises and drops. As a result, we achieve a smooth output that oscillates between two tones, simulating a police siren.


  • Hobbyist Projects: This circuit is an excellent choice for electronics enthusiasts who enjoy building and experimenting with different circuits.
  • Alarm Systems: The police siren circuit can be integrated into alarm systems to enhance their effectiveness.
  • Vehicle Simulations: By combining the police siren circuit with a police lights circuit
  • Educational Demonstrations: The police siren circuit uses in educational settings to demonstrate the principles of sound generation and modulation.
  • Creative Projects: Artists and designers can incorporate the police siren circuit into their installations or performances to add an interactive and dynamic element to their work.

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