Triggered filter to work on

[StephenGiles]

Oh yes, I deleted it instead of moving it - should have left it alone this evening! Thanks Snap.

[R.G.]

in the new schem, why switch the current-intensive output of IC1d instead of its noninverting input?

Because what you want when the one-shot times out is not a zero voltage from IC1D, but a high impedance so the capacitor can run down through the sweep resistors. If you only switch the input, then the output of IC1D drives the cap ... fast... to wherever its input goes. Not a sweep.

[snap]

so you could sample&hold the envelope voltage at the input with 1 or 2 of the leftover bilateral switches plus a small cap for the time the oneshot is "on".

[StephenGiles]

I've updated to version 3.
http://img.photobucket.com/albums/v517/uncle_boko/CamillaFilter3.gif

Hopefully I'll spend some time breadboading this later.

[R.G.]

Just as a final fillip to play with:

If you can make one filter sweep up and one down, then up during the sweep and you also get the frequencies righ, this will produce a sweep through several vowel sounds...

[StephenGiles]

Sounds interesting.