Cgs synth

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/>
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