Electronic Siren Circuit Diagram
siren circuit using 555 timer
We are going to make a Police Siren Circuit using two 555 timer IC. The circuit will produce an up-down wailing sound from the speaker. In this circuit there are two 555 timer ic is used.
Both 555 ic is connected as astable multivibrator/oscillator. In an Astable mode, it delivers a continuous sequence of pulses on its output Pin No. 3, the capacitor C1 charges and discharges continuously.
The first 555 is wired as a low-frequency astable oscillator. IC2 is wired as a Fast astable Oscillator and the output of the first ic from pin 3 is connected to shift the signal with control voltage pin 5 of the second 555. Whose frequency is modulated depending on the varying voltage from the IC U1. The voltage shift on pin 5 makes the frequency of the second oscillator rising and fall.
The frequency range of the siren can vary with changing the value of R2 and R4 resistor with a potentiometer variable resistor.
The circuit can be made with one NE556 ic at the place of two separate 555. 556 has a dual 555 timer. Output sound can be Amplified for high pitch by using any audio amplifier to make a loud sound.
This circuit can be assembled on any general-purpose PCB/Vero board
555 timer IC – 2
68K Resistor – 1
1K Resistor – 1
10K Resistor – 3
10uf Capacitor – 2
o.1u (104)capacitor – 2
Speaker – 1