Electronic-siren


Posted on May 3, 2012

The wailing sound of a siren is generated by a VFO consisting of Q1 and Q2. Capacitor C2 provides the feedback for the oscillator. The frequency of the oscillator is varied by the voltage applied to the base of Q1 through R3. When switch S1 is closed, capacitor Cl charges, thus increasing the oscillator frequency. When S1 is released, capacitor {;1 discharges, and the oscillator frequency decreases.


Electronic-siren
Click here to download the full size of the above Circuit.

Capacitor C3limits the maximum oscillator frequency. The average battery current drain is about 15 mA.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

8 Note Tune Player
Touch Switch with MPF102 JFET
Solar cell battery charger circuit
Oscilloscope Preamp
12 Volt Lead Acid Battery Meter Led
Line Following Robot Sensor
Difficulty with Common Emitter Amplifier
GPS USB Dev Board
hard disk switch schematics
LED ramping circuit
Electronic Stethoscope
Receiver schematic design using MC3335PSSB



Top