The Loud Siren Circuit is able to produce Ambulance Sirens, Fire Sirens, Machine guns, and Police sirens with the help of switching. This loud Siren circuit has IC UM3561 which is a CMOS IC often used as alarms in toy applications and has the ability to work with as low voltage as 2.4V.
Hardware Required
The following components are required to make Siren Generator Circuit
| S.no | Component | Value | Qty |
|---|---|---|---|
| 1. | NPN Transistor | TIP120 | 1 |
| 2. | IC | UM3561 | 1 |
| 3. | Zener Diode | – | 1 |
| 4. | Speaker | 8Ω | 1 |
| 5. | Switches | – | 3 |
| 6. | Resistor | 470Ω, 1KΩ, 150KΩ | 1, 1, 1 |
| 7. | Power Supply | 12V | 1 |
| 8. | Breadboard | – | 1 |
| 9. | Battery Clips | – | 1 |
| 10. | Connecting Wires | – | 1 |
UM3561 Pinout
For a detailed description of pinout, dimension features, and specifications download the datasheet of UM3561
Siren Generator Circuit
Working Explanation
The IC has an inbuilt oscillator circuit that generates the necessary clock for the operation of the IC. A resistor connected to OSC1 (PIN 7) and OSC2 (PIN 8) determines the frequency of the oscillation. The generated oscillations will be passed on to the control circuit where tones are selected through the connection of SEL 1 (PIN 6) and SEL2 (PIN 1). The pulses thus generated are made available through output PIN 3. An NPN transistor TIP120 is necessary to amplify the weak sound signal to the loud siren circuit.
Changing the pin connections that are SEL1 and SEL2, the siren tones can be changed.
