Simple Electronic Siren Circuit

This simple electronic siren circuit project aims to explain designing a simple circuit for an electronic siren. It is built on a single chip – CD4011 (IC1). In order to make this work, we need four NAND Gates with 2-input of IC1. Both the gates will be configured to manage high and low frequency oscillator.
The conduction D2 Diode in the circuit responds when there is high output from low frequency oscillator and further enables high frequency oscillator. To change the speed of the oscillator, the value of C3 capacitor can be raised to 8µF.
To tone the changer components, the C1 Capacitor and R1 Resistor are used in this design. Also, in order to let the D1 Diode operate at its full output we have used C2 capacitor. The T1 Transistor in the circuit is used as speaker driver.
Following is a circuit diagram of the electronic siren:

simple electronic siren circuit
Electronic Siren Circuit Diagram
Here lists below the components that you need to design the project:
Resistors Capacitors Semiconductors Others
R1 = 150 KΩ C1 = 0.015 µF IC1 = CD4011 LS1 = 8Ω speaker
R2 = 500 KΩ C2 = 0.22 µF T1 = BEL187
C3 = 0.5 µF D1 = 1N4148
C4 = 10 pF D2 = 1N4001
NOTE: All resistors should be ¼ watt and ± 5% Carbon.