How to Make a Siren Generator

Details

Learn How to Make a DIY Electronic Siren Generator circuit that can produce police car siren, emergency ambulance siren & fire brigade sound using the IC UM3561a Siren Tone Generator.

The circuit only requires a few components and can be put together in a couple of hours. Since the siren is multipurpose, it can be easily configured to suit it's vehicle's siren requirements.

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Build Instructions

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Step 1: Parts & Tools
Components:
- 1x UM3561 AliExpress
- 1x BC547 NPN Transistor AliExpress
- 1x 220KΩ Resistor AliExpress
- 2x 220Ω Resistor AliExpress
- 1x 5mm LED AliExpress
- 1x SPDT Slider Switch AliExpress
- 1x SP3T Slider Switch AliExpress
- 2x 2-Pin Male Header Pins AliExpress
- 1x Speaker AliExpress
- 1x AA Battery Holder (2 Slot) AliExpress
- 2x AA Battery AliExpress
Tools:
- Soldering Iron AliExpress
- Soldering Wire AliExpress
You can also Buy the PCB: PCBWay
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Step 2: UM3561 Explained

The UM3561 is a low-cost, low power CMOS LSI designed for use in toy applications. Since the integrated circuit includes oscillating and selector circuits, a compact sound module can be constructed with only a few additional components. The UM3561 contains a programmed mask ROM to electronically reproduce alarm sounds.
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Step 3: Circuit Schematic

Only one of the Siren tunes can be played at a time. This is determined on the basis of the position of the SP3T Slide switch. The switch has three positions which will connect the common terminal with VCC, GND or NC in order to fulfill the Truth Table.

The 220KΩ resistor is used to set the oscillating frequency of the IC.

A dynamic speaker is driven with an external NPN transistor. An SPDT switch is used to turn the circuit ON & OFF.

Eagle Schematic: GitHub