[sdiy] Crossfade circuit for CVs?

[jorgen.bergfors at idg.se]

>Have you considered PWM?  The Buchla model 257
>voltage processor did it that way.  The schematic is available
>on-line somewhere.

I thought of PWM, but preferred an all-analog (time discrete) solution. But
now I realize that PWM is probably the best solution.
As the circuit is going to be used to control Vactrols, the PWM can be of
moderate frequency, without risking a breakthrough of the PWM frequency.

/Jorgen