[sdiy] Which programable chip?

[Jason Proctor]

>Somewhere or another I remember seeing an appnote which suggested
>using the analog muxes to switch inputs into the virtual ground
>summing junction of an op-amp.
>
>I've gone digging for it, but lamentably I don't seem to have a 
>softcopy. And no, I can't even remember who published it.....
>
>Ring any bells, anyone?

one example of this is Ken Stone's CGS28 sequential switch --

http://cgs.synth.net/modules/cgs28_seq_switch.html