Dual-tone car horn

Posted on May 17, 2012

An LM556 dual oscillator/timer, U1, configured as a two-tone oscillator drives U2, a dual 4-watt amplifier. One of the oscillators, pins 1 to 6, contained in U1 produces the upper frequency signal of about 200 Hz, while the second oscillator, pins 8 to 13, provides the lower frequency signal of about 140Hz.

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

Increase or decrease the frequencies by changing the values of C2 and C3. U1's outputs, pins 9 and 5, are connected to separate potentiometers to provide control over volume and balance. Each half of U2 produces 4W of audio that is delivered to two 8 ohms

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