[sdiy] A diode-ring SVF

[René Schmitz]

Hi Aaron and all,

> Alas, he can't seem to get anything going... If you tap into the BPout 
> and LPout, you just hear noise (and see it on the scope) its seems.
> 
> The control circuit is based off the MOTM-485, since I figured you 
> probably can't get a better control front end than whatever Paul did. I 
> didn't have any of the op amps that Paul used, so I gave Chris some 
> LM358s, which we later swapped out for some TL072s just to have 
> something to try.

Watch out for the biassing, the compliance of the -Icon is ~0V, so there 
is not enough room for the lower diodes, since their other end is at a 
virtual GND. Either rebias the filter core upawards so that the virtual 
GND is somewhat positive. Or rework the current sink so that it sinks to 
-Vcc instead of GND.

Cheers,
  René

-- 
uzs159 at uni-bonn.de
http://www.uni-bonn.de/~uzs159