Warble Alarm Circuit

Posted on Oct 11, 2012

This circuit uses a 556 to first generate a low frequency square wave, that is modulated to produce two alternate tones of about 400 and 500 Hz. Circuit generates warble alarm of European emergency vehicles.

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

The frequencies of the oscillators are determined by the values of Rl, CI and R2, C2.

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