Wailing alarm


Posted on Feb 6, 2013

This circuit simulates the sound of an American police siren. IC2 is wired as a low frequency astable that has a cycling period of about 6 seconds. The slowly varying ramp waveform on Cl is fed to pnp emitter follower Ql, and is then used to frequency modulate alarm generator IC1 via R6. IC1 has a natural center frequency of about 800Hz.


Wailing alarm
Click here to download the full size of the above Circuit.

Circuit action is such that the alarm output signal starts at a low frequency, rises for 3 seconds to a high frequency, then falls over 3 seconds to a low frequency again, and so on ad infinitum.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

Serial Voltmeter using the PIC16C71
Doorbell
Modular Music Box Arduino polyphonic audio
Simple audio mixer circuit with fet 2n3819
Lithium Ion Charger 2 Cell
Gas Leak Detector Circuit
Optical Heart Rate Monitor
A S/PDIF Free Space Digital Audio Optical Link
AVR robots
Digital Sample And Hold
Cutoff frequency 48dB-octSCF low-pass filter circuit
A feedback circuit and the differential input stage bias circuit is provided separately



Top