Hee-haw-slren


Posted on Apr 19, 2012

A pair of timer IC`s are the heart of a circuit that simulates the warbling bee-haw of a British police siren. One of the 555 timers, U2, is wired as an astable multivibrator operating at about 900 Hz. The other, Ul, operates at approximately 1 Hz. Its output at pin 3 is a square wave with a 50% duty cycle-on and off cycles of about 0.5 second each. The output of Ul is applied to pin 5, the control-voltage terminal of U2.


Hee-haw-slren
Click here to download the full size of the above Circuit.

The frequency of the 555 timer IC is relatively independent of supply voltage, but can be varied over a fairly wide range by applying a variable voltage between pin 5 and ground. When Ul "s output becomes high, U2 operates at about 800 kHz. That switching between two frequencies produces the warbling hee-haw signal.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Liquid level control
Low-distortion-video-buffer
Audio 5 Band equalizer using IC BA3812L
voltage to frequency converter icl8038
Esposito Wang
5x10 vu meter
Iso buffer serial to parallel converter
Digital delay circuit lamp circuit 3
Switching power supply drive circuit



Top