SIREN CHEAP AND EASY

In this project, two 555 timer IC's were used the first one is operating in Astable mode ( ie output is switching between high and low without any intervention from the user ) and is used to designed such that to produce a low frequency. Well the second one also operating in Astable mode but it is driven by the output of the first timer by using the control voltage pin 5 .Due to this up and down in the control voltage it produces a wailing sound. The Police Siren circuit uses two 555's to produce an up-down wailing sound. The first 555 is wired as a low-frequency oscillator to control the VOLTAGE CONTROL pin 5 of the second 555. The voltage shift on pin 5 causes the frequency of the second oscillator to rise and fall. 

You can also apply it for some different sound like Ambulance , Police Car , Alert Alarm etc by changing the frequency of the first timer all you have to do is to change different resistance by using the potentiometer and try some different valued electrolytic capacitors .

LIST OF COMPONENTS
1. NE555 timer ic (2)
2. 10uF electrolytic capacitor (2)
3. 100nF Ceramic capacitor (2)
4. 10k resistor (3)
5. 1k resistor (1)
6. 68k resistor (1)
7. Speaker 0.5 watt OR any (1)
8. 9v battery and clip (1)
9. One small breadboard (1)
10. Some jumper wires.














 CIRCUIT DIAGRAM

Wave generated by this circuit in in square wave as shown in the diagram below