Organize and Share your Electronics the way you want. Sign-Up for a free account now. It takes only 30 seconds!

Emergency Siren Simulator

Emergency Siren Simulator

This siren circuit simulates police, fire or other emergency sirens that produce an up and down wail.
The heart of the circuit is the two transistor flasher with frequency modulation applied to the base of the first transistor. When the pushbutton is depressed, the frequency of oscillation climbs to a peak and when the button is released, the frequency descends due to the rising and falling voltage on the 22 uF capacitor. The rate of change is determined by the capacitor value and the 100k resistor from the pushbutton. The oscillation eventually stops if the button is not depressed and the current consumption drops to a tiny level so no power switch is needed.

The 0.1 uF determines the pitch of the siren: A 0.047uF will give a higher pitch siren and a 0.001 uF will give an ultrasonic (at least for me, anyway) siren from 15 to 30 kHz which might have an interesting effect on the neighborhood dogs! The 33k resistor from the collector of the PNP to the base of the NPN widens the pulse to the speaker giving greater volume.

Visit Here for more.

 

More Articles to Read

Muxtronics open source 12V powerbank
Muxtronics open source 12V powerbank
TI’s Little Professor
TI’s Little Professor
App note: Testing inductors at application frequencies
App note: Testing inductors at application frequencies
1968 Princeton Reverb Repairs
1968 Princeton Reverb Repairs
Skill Sunday: Power Over Ethernet for Arduino
Skill Sunday: Power Over Ethernet for Arduino
More on Color TFT Displays ~ The Big Ones — 240 X 320
More on Color TFT Displays ~ The Big Ones — 240 X 320
Magnetic Rotary Encoder
Magnetic Rotary Encoder
Vertical Pole Climbing Robot
Vertical Pole Climbing Robot
ESP8266 Weather Station Projects
ESP8266 Weather Station Projects
Single tube Lethal Nixie clock
Single tube Lethal Nixie clock

Top




Shares