[sdiy] Envelope following -> grafting to knobs

[harrybissell]

Honestly... its not trivial at all.  Pots are a wonderful thing that have
certain characteristics...

1)  Zero offset voltage
2) (almost) unlimited signal handling capacity
3) (almost) zero wiper-end resistance
4) choice of many resistance tapers (vs rotation)

So replacing them with voltage controlled devices can be hard...
usual suspects are

1) several photocells
2) several fets
3) one or more VCAs
4) motor operated pots

The biggest issue is whether the pot is used as a three
terminal device (pot), or as a two terminal (variable resistor)

You will really have to look at each individual circuit to see what
are the most important attributes of the design to find a suitable
replacement.  Send a link to a particular schematic and we'll take a look.

H^) harry

nN AAt e e wrote:

> i have wondered about this on and off for a while... its simple to replace a
> pot with a volume or control pedal, but... how does one go about replacing a
> pot [or converting the pot to offset] with an input for CV control? most
> voltage control schematics are still a little over my head for understanding
> what the main differences are between schematics for things like voltage and
> non voltage controlled mixers etc...
>
> are there any just sort of traditional circuits you can use where all you
> really have to do is match the impedance on the pot and then graft it on?
>
> this really just kind of came off of the idea for making some pedals with
> routable envelope following.
>
> a guitar pedal with a cv matrix would be so weird and cool...
>
> - nate - www.robot-dreams.com