[sdiy] Crossfade circuit for CVs?

[jorgen.bergfors at idg.se]

Hi all. I need a simple circuit that can crossfade between two different
CVs, using a third CV.
It doesn't have to be particularly linear or anything. But it needs to be
simple, as I'm going to use a whole bunch of them, in a planned module.
I have a crossfade VCA, that I could use, but it uses two 3080 and five
op-amps. I'm trying to find something with lower parts-count.

/Jorgen