[sdiy] minimoog VCF clone, please help

[Linium]

On Mercredi 26 Mai 2004 16:15, rawarmy at saunalahti.fi wrote:
> hello everyone.
> im new to building synths but eager to learn more.
> i have been able to build my first module which is minimoogs VCF. all
> components are on board but dont know how to do the wiring.
> i just simply dont know where does all the knobs and audio in/out wires
> go. i made my module according to jörgen bergforss BERGFOTRON and no
> where in those documents were told how to do this wiring.
> please help me out on this. is there any web pages which tells how to do
> it? or does anyone had any documentation on wiring?
>
> thanks
> ami

You need the schematic, unfortunatly Jorgen doesn't seem to provide it for his 
Minimoog VCF clone. May be could you try to email him, and hope he has some 
time and kindness to provide the informations you need ?

But look and the original schematic from Rene Schmitz's site from wich this 
clone is inspired and you can find some hints where audio/cv inputs and 
outputs are:
http://www.uni-bonn.de/~uzs159/rsmoog.png

On this schema the two 10k lines at the bottom left are audio inputs. And the 
"to vca" on the top is the out. 

Now half the job is done. All you need is to find frequency and resonnance 
controls.  The resonnance is the 47k pot at the left on the empathis path. 

So the last one is the frequency knob ! There is none shown on this schemo.
But look at the top-left, there are three 100k lines. That's where the 
frequency cutoff variations come in.  You would need to put a voltage on 
theses lines to modulate the frequency. It can be either an external LFO (CV) 
or a knob.
For a knob you can buy a 50k linear to make a "divisor bridge" and connect the 
center pin to one of theses 100k lines. That's all !

Now you have to translate all this to see how it fits to the Bergfor's design. 
I bet it shouldn't be that hard ! 

Hope it helps,

Linium