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

Put-battery-charger
3-30V-universal-power-supply-module
Audio Memo Alert Circuit
Alarm Dialer Circuit
Scheme research and design of the ultrasonic range measurement system
EFHW Tuner
switch with relay schematic
24hr clock using logic ics
pic LM032
Combinatorial and Sequential Circuits
25kHz using thyristor inverter welding machine circuit



Top