PLAN B analog blog

Wellll....

Hmmm...within the module it'll be a bitch, especially the Square/Pulse
port.  But you could add a couple of op amps, one just inverting with ground going to the reference input (in this case the +) and
the second also inverting,  yet with a trim pot going from the - and +
rail in the positive input insead of a ground reference.  That would
do it.

So internally you'd have to hang another little board and you'd route the one of the outputs (either the tri/saw or square/pulse), but first replacing it's 1K output resistor wth a 100K into the neg input of the first op amp with the positive input tied to ground, then use another 100K as it's feedback resistor, then the output of the first op amp through another 100K into the negative iput of a second op amp, use another 100K as that op amp's feedback, then the output of the second op amp through a 1K to the faceplate jack.  But instead of connecting the second op amp's reference (positive) input to ground, connect a trim pot which swings between full - and full + and that'll work as an offset so you can push the output waveform up and down vertically to the point it's fully offset on the positive end. 

Second option:  A model 14!!

Third Option:  A model 10 and use that for the positive LFO

I wish I could have done more with all of the ELFs...but those guys
are small and we had to make some hard decisions in all cases.

- P




--- In PLAN_B_analog_blog@yahoogroups.com, "metafoetus2002"
<jan-hinnerk.helms@...> wrote:
>
> Hi Peter,
> 
> thanks for the welcome and the explanation. Is there an easy mod
that would make just the 
> sawtooth output swing positive only?
> 
> Best regards,
> Jan-Hinnerk
> 
> --- In PLAN_B_analog_blog@yahoogroups.com, "(i think you can figure
that out)" 
> <peter@> wrote:
> > All of the waveforms on the M37 are AC, swinging both sides of ground.
>