Factory Siren Circuit Schematic Diagram

With this circuit, you can produce the same siren sound like what is used in the factories. This circuit uses IC timer 555 with astable multivibrator mode which can produce oscillating frequency 300 Hz. Output frequency of the timer can be controlled by changing the value of VR1 and VR2. Here is the schematic :

Factory Siren Circuit Diagram

Components :
Resistor R1 : 10k ohm
Resistor R2 : 56k ohm
Variable resistor VR1-VR2 : 10k ohm
Capacitor C1 : 0.01 uF
Polar capacitor C2 : 1 uF/15V
Polar capacitor C3 : 1,000 uF/15 V
IC Timer : NE 555
Speaker 8 ohm 0.5 W
5-15V power supply

Estimated price : $2