Variable ramp generator

[tomg]

> > I know, it is possible to independently control the charge and
> > discharge times in integrator by using a pair of diodes or
> > a CMOS switch. AFAIR, Juergen described such operation of KORG
> > LFOs. The problem is if one applies this control scheme to VCO
> > it leads to severe tracking problems.
> 
> No way to use this Korg circuit for a tracking VCO. (Schemos are
> on the web somewhere, btw.)
> 
> I remember Don Tillman once offered an idea how it could work,
> but I've never tried it or followed it further. Don ?
> 
> JH.

Nationals LF411 app notes show such a circuit. I played with it a little. Some
minor changes and it worked....ok.

Tom