Thanks, will do.
Mitchell
Mitchell
--- In cgs_synth@yahoogroups.com, sasami@... wrote:
>
> You need to add a pot in the feedback loop. Reduce the 100k to 82k and put
> in a 50k trim pot. This will allow you to adjust the gain for exactly unity.
> Chances are your 100k resistors don't quite match.
>
> Ken
>
> >I just built an LM337 based -2V DC circuit in order to add offset to my
> .com's oscillators
> >(because they don't go low enough unless you switch them into "LO" mode
> which is really
> >hard to tune properly). It works perfectly when I use two of the CV ins on
> the oscillators to
> >mix the MIDI>CV voltage with the -2V offset voltage.
> >
> >For convienience and to save patching, I want to physically "piggyback" the
> board on my
> >MIDI>CV converter module, install a switch to turn the -2v source on/off,
> and mix the -2v
> >with the MIDI>CV converter's pitch output voltage to achieve the offset
> (i.e. so it all appears
> >on the single MIDI>CV output jack.
> >
> >When I tried using the DC mixer board to mix the two voltages, it threw off
> the keyboard
> >scaling by about a half step over a three octave span. Is there anything I
> can do to maintain
> >the correct scaling, or is the DC mixer circuit not capable of doing so?
> >
> >(btw, my DC mixer doesn't have any pots in the circuit at all, just 100k
> resistors)
> >
> >thanks in advance!
> >
> >Mitchell Sigman
> >
> >
> >
> >The CGS Modular Synth home page: http://www.cgs.synth.net/
> >
> >Yahoo! Groups Links
> >
> >
> >
> >
> _______________________________________________________________________
> Ken Stone sasami@...
> Modular Synth PCBs for sale <http://www.cgs.synth.net/>
> Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>
>