Siren Generation Using IC UM3561




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.


  • 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.



    • Sensors Contest

      Sensors Contest
    • Backyard Contest

      Backyard Contest
    • Pets Challenge

      Pets Challenge

    12 Discussions

    Naveen Mekala

    1 year ago

    what is the future scope of the project?

    In UM3561 UM indicates for?

    1 reply
    Ruby Laser

    1 year ago

    Note for anyone wanting to replicate this without using a UM3561: The UM3561 IC datasheet specifically says that it uses a mask ROM (which basically means it is not programmed electrically, rather it is "programmed" during chip exposure). This also means that it cannot be replaced easily with, for example, a 555 timer.

    However, if someone HAD to replicate it without a UM3561 it COULD be done using just capacitors, wire, resistors, transistors, and diodes. To do it make a shift register circuit in a decade counter configuration so that each clock cycle it activates the next address pin of a Diode-ROM array (and turns off the previous one). Lastly, a selector circuit must be made to activate the different ROMs, and a DAC (digital to analog converter) must be added to convert the binary values into an analog signal.

    However, the diode ROM array would require a lot of transistors and a lot of diodes (around 30,000 transistors and an uncountable number of diodes). This is because an audio signal is between 500 and 1550 hertz for a typical siren. Which means the number of transistors (just for the ROM) can be calculated (in theory) by using the calculation:

    (1550 X 10) X 5.5.

    And the maximum diode count (for the ROM) could be calculated by multiplying the value from the last equation by 8 (the lowest bit value required for decent sound quality). This value is probably off by about 10-30% because all of the values in the Diode-ROM array are not going to be zero.


    2 years ago

    Wat software can i use to simulate the siren generator um3561


    2 years ago

    My DIY Alarm Siren, without additional components using only a Speaker


    I think the police siren and the ambulance siren sound exacly the same though!


    4 years ago

    I don't have um3561 ic .will it work if I use a 555 timer ic,if yes pls tell me how.

    1 reply

    Reply 4 years ago on Introduction

    No it won't work with 555 timer IC. Basically this IC has inbuilt siren sounds that I have used by different connects.