Introduction: Police Siren Circuit Using 555 Timer IC

By http://www.vsgupta.in/
About: Works full time in corporate. Makes free tutorial in free time for open source community.

We are going to make a Police Siren Circuit using two 555 timer IC. The circuit will produce an up-down wailing sound from the speaker. We will be using two 555 timer IC, so the circuit will be bit complex to make. We will fire first 555 is wired as a low frequency oscillator to control the voltage control pin 5 of the second 555. The voltage shift on pin 5 makes the frequency of the second oscillator to rise and fall. I will explain each step in detail with step wise execution and instructions of the circuit.

Step 1: Bill of Materials

For this circuit, you will need these components:

  • Mini Breadboard - 1
  • 9V battery - 1
  • Wire Stripper - 1
  • Battery Snapper - 1
  • Nose Plier - 1
  • 555 timer IC - 2
  • 68K Resistor - 1
  • 1K Resistor - 1
  • 10K Resistor - 3
  • 10uf Capacitor - 2
  • 100n capacitor - 2
  • Speaker - 1

Step 2: Schematic

Keep the circuit diagram handy. While making the breadboard connection, please check your connections with the circuit diagram. It will help you to avoid any errors on breadboard.

Step 3: Video

Watch this video and follow the step by step instructions to make the circuit on breadboard.

Step 4: Breadboard Image

Use this breadboard image for your reference.