[sdiy] WP LM3900 VCF

[harrybissell]

Hi Johannes

simply put... most VCO are linear response. The expo control is almost
always an add on.  It might even be a 'tack on' if the original design
is good enough. (usually you need a pretty linear VCO to use it
sucessfully
with an expo converter).

I can't think offhand... of a VCO that is inherently an 'expo' design.
(list ??? :^)

Most VCO designs are really a CCO (current controlled oscillator) with a
voltage to current converter 'tacked on' as well...

The WP design is for sure a true VCO, and probably would not expo
easily. There
are better ones to start with. It is cheap and dirty, and quite useful
as it is.

H^) harry

Johannes Öberg wrote:
> 
> Btw, how do you "see" if a VCO or something has linear or log vc? Does
> the Gnome VCO have it? How about the WP-20 VCO? It seems that
> simple/few-parts VCO's tend to have linear control. Is log control in
> fact always a 'tack-on'? (as in: you could remove some components from
> every log vco and get a lin vco)
> 
> /J