sqr to saw (was: Wasps, DCOs, OSCs and Bill Clintons pants?)

[Haible Juergen]

	>I remember Elektor back in the good old days (ca 1979) had a very
clever 
	>circuit that converted a square wave to a sawtooth. It worked for
any frequency 
	>that would be used in a musical instruments. The article said it
was patented 
	>but that patent has probably expired now. I think I built it back
then and that 
	>it indeed worked as advertised. I can probably dig up that issue if
there is 
	>interest for it.

I vaguely remember this - didn't it work with an amplitude regulation
loop ? What happens when the frequency changes immediately ?

It's a fundamental problem: A square wave does only carry the 
information of the discrete time of its zero crossing. So there is
no way to predict the next zero crossing when the frequency changes.
Therefore every correction of the SAW ramp time comes too late.

This does not mean that it dosen't sound good, of course.
The WASP (you all have the schemos now, don't you?) has
a frequency to voltage converter that controls the ramp time.
With the same problems as above, plus a more or less staircase
type waveform, and with the advantage of having higher footage
square waves to generate the lower footage ramps - not perfect,
but sounds good. And look at that highly economic design !

JH.