On Sat, 19 Jul 2003 17:39:23 GMT, John Popelish
wrote:

Paul Burridge wrote:

Feed the square output to a coil+capacitor in parallel and you'll get
a sine wave. Tune the this 'tank' circuit for harmonics of the
funamental and you can double, triple, quadruple and so on the
original square wave's frequency.

This works pretty good at the third and fifth harmonics, but there is
no second or fourth harmonic in a perfect square wave.

Good point, John. But fortunately, I've never generated a *perfect*
square wave! :-) In practice, it's probably more accurate to say that
the even harmonics are well down on the odds. Blame it on dv/dt.