I don't own an oscilloscope myself. But if the DCO outputs are offset
by +5V, thus oscillating around +5V you can make a symmetrical signal,
thus one that oscillates around +0V, simply by running it serially
through a capacitor, removing the very low frequencies. Select it
large enough to let all desired frequencies pass nicely. Then you
could control the voltage range by a potentiometer. This would most
probably be a nice mod. I'm not looking at the schematics, but since
you now have two drivers for one input (VCF-Cutoff), you should
connect them through a resistor or something, so that you don't create
any short circuit.
I'm new to this stuff, so please correct me if something is wrong. :)
> then i was trying to make DCO->VCF modulation but i found out that the
> DCO outputs are offset by +5VDC or so... i kinda figured that out
> without an oscilloscope - just with a multimeter and
> wires->mixer->soundcard and trial and error. is that true? what's the
> easiest way to drop that signal down 5VDC? i think it can make quite a
> nice mod.