Emergency Siren circuit Simulates Police
This attractive compound simulate police, fire or other emergency sirens, which produce up and down wail.
In the heart of the chain are two flasher transistor with a frequency modulation applied to the base of the first transistor. When pushbutton is depressed, the frequency of wave climbs to the top when the button is released, the frequency descends due to increasing pressure and lost 22 uF capacitor. The rate of change is determined by the value and capacitor on 100k resistor from pushbutton. Oscillation eventually stop if the button is not depressed and current consumption drops to low-power level, it is not necessary shift.
Tags (other circuit ) : audio alarm, Emergency Siren, greater siren
