IC UM3561 is a siren generator IC generally used in alarms and toy applications. Depending on the selection, it can generate 4 different types of sirens which are – ambulance siren, fire brigade siren, police siren and gun sound. Here we will see how we can make these different siren sounds using different selections in the IC. So here are all the different types of siren circuits which can be created using IC UM3561 – ambulance siren, machine gun sound, fire brigade siren and police siren circuit.

Step 1: UM3561 Pin Diagram and Description

Pin No. Symbol Description

1 SEL2 Sound Effect Selection Pin No.2

2 Vss Negative of Power Supply

3 OUTPUT Mono-tone Output

4 NC Internal Testing Pin : Leave Open for Normal Operations

5 Vdd Positive of Power Supply

6 SEL1 Sound Effect Selection Pin No.1

7 OSC1 External Oscillator Terminal 1

8 OSC2 External Oscillator Terminal 2

Step 2: How to Generate Different Types of Sirens Using IC UM3561?

As shown in the above pin diagram, pin 1 (SEL2) and pin 6 (SEL1) are the selection pins. We can use these two pins to select the siren sound as per given in the below table.

SEL1 SEL2 Siren Generation Circuit

NC NC Police Siren

VDD NC Fire Brigade Siren

VSS NC Ambulance Siren

X VDD Machine Gun

NC – No Connection

X – Don’t Care

So as per the table above, we are going to create these 4 circuits. The components required for all these circuits are listed here:

IC UM3561

Transistor BC547

Resistors – 220k and 1k

Speaker – 8 Ohm

3V Battery

Step 3: Police Siren

To create a police siren circuit you need to create connections as per shown in the below circuit.

Steps:

Adjust IC UM3561 on middle of the breadboard.
Leave pin 1 unconnected and connect pin 2 with ground pin battery.
Connect pin 3 with the base of transistor BC547 using 1k resistor.
Connect the negative end of speaker with the collector of transistor and positive end with the positive end of battery.
Connect emitter of the transistor with ground battery.
Leave pin 4 unconnected and connect pin 5 with the positive of battery.
Leave pin 6 unconnected. Connect pin 7 and pin 8 using a 220k ohm resistor.

Step 4: Fire Force Siren

The components required and basic connections of the circuit remain same. Just connect the pin 6 of IC with the positive end of battery and siren selection will change from police siren to fire brigade siren. This configuration can be used in a simple circuit like this fire alarm circuit to make it more interesting and useful.

Step 5: Ambulance Siren

To create the ambulance siren, just connect the pin 6 (SEL 1) with ground pin removing from positive pin of battery.

Step 6: Machine Gun

This circuit can be used in DIY games to make them more interesting. To create the gun sound from UM3561 IC, leave the pin 6 unconnected and connect pin 1 with the positive end of the batter.