Posted on Jan 22, 2013

This free-running TTL square-wave oscillator has a variable frequency output over a 20:1 range or better through use of four of the six inverters in an SN7404 chip and the additional components shown. Frequency of oscillation is determined by the capacitor and the settings of potentiometers R2 and R4; the first pot controls width Tl and the second controls width T2 of the square-wave output.

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

These adjustments are not completely independent.

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