Doepfer

Hi,

I want to build my own filter just for fun and have already red a lot about different filter topologies and poles and stuff. But I can't find any schematics about how to control the filter frequ just with one mono pot -- since you actually have to change the cut-off freq of each pole in a filter simultaneously, so you would need a stereo pot for e.g. a 2-pole and so on...

Guys, what is trick?
An example schematics would be great.

Olli

> Hi,
>
> I want to build my own filter just for fun and have already red a
> lot about different filter topologies and poles and stuff. But I
> can't find any schematics about how to control the filter frequ
> just with one mono pot -- since you actually have to change the
> cut-off freq of each pole in a filter simultaneously, so you
> would need a stereo pot for e.g. a 2-pole and so on...
>
> Guys, what is trick?
> An example schematics would be great.
>
> Olli

You have to design a voltage controlled filter. Then a mono pot can be used
to generate a voltage that controls the frequency of the filter independent
of the number of poles. There are a lot of voltage controlled filter
schematics available in the net.

Best wishes
Dieter Doepfer