[sdiy] random thought about sine shapers

[David G. Dixon]

> That's one thing I was going to request once you got to designing the
> shaper :-) sin/tri.. if you can get square in too, that's better, if
> you can get PW in, that's even better. No, there's no reason you
> shouldn't have it on the front panel :-) But make sure there still are
> trimmers so that you can actually tune it up.

I've already got all the shapers.  The sine shaper is a Thomas Henry
special, and it's brilliant.  The shape pot (a 100-k, 18-turn Bourns trimmer
in my units) gives near-perfect sines at about halfway (46.4k, according to
simulations).  That's the one I'm pondering to put on the panel.

> Another popular one seems to be saw/PW, but I don't know how it works.

Easy: you just feed a saw to the pulse comparator rather than a triangle.

> > A question:  What does a typical waveform selection knob actually do?
>  Does
> > it simply crossfade from one static waveshape to another, or is it
> > performing an actual waveshaping function, like a sine shape trimmer?
> 
> do you mean potentiometer or switch?

I don't know.  Are they typically rotary switches or pots?  (I have very
little experience with actual modulars.  I've only ever laid my hands on a
couple, and they didn't have this sort of function.)

> A switch would probably just tap outputs at different stages of the
> shaper, my guess..

Maybe.