[sdiy] Miniwave question

Ross Oldenburg oldenburg at gmail.com
Tue Oct 9 03:45:58 CEST 2012


I also have the Miniwave.  What an awesome module!

Your "switch wiring problem" is in how I think you're interpreting the
labels.  You said your VCO is 10v p-p, which means that, assuming AC
coupling, the output will be from -5V to +5V.  This is normal for
VCO's, so you should use the +/- 5V setting.  The +10V setting accepts
inputs from 0 to 10 volts, like you'd get from an ADSR.  So the +/-5V
accepts the entire swing of your VCO, while the +10V setting will only
register anything when the VCO is above 0V.

About your glitch, if you change RT1 and RT2, you'll need to change
RT3 and RT4 as well.  It's sort of a delicate balancing act (ah the
glory of analogue, even when it interfaces with digital!).  Try going
through the calibration procedure in the manual a few times.  And keep
in mind that the manual does say, "These adjustments are designed to
match the MiniWave to the specific VCO used for input."  Not that you
should recalibrate every time you repatch, but something to keep in
mind.  :)  It won't always be perfect.

I don't have my scope handy, otherwise I'd see what the output of my
MW looks like.  You probably just need to calibrate, recalibrate, and
re-recalibrate until you get it "close enough". :)

Ross O.

On Mon, Oct 8, 2012 at 4:00 PM, Tom Arnold <xyzzy at sysabend.org> wrote:
> FInally bought and built a miniwave, then got sidetracked building a dedicated
> VCO to drive it.  So I now have a nice stable 10v p-p sawtooth.  I'm going
> to ignore one problem I'm having ( bottom half of waveforms missing when
> switch set to 10v, but available when in +-5 mode ) as I may have a switch
> wiring issue...  I'm curious about a glitch on the waveform.
> I'm getting a tiny glitch on the rising edge of waveforms about halfway from
> 0 to peak.  Playing with trimmer 1 & 2 can minimize it but never quite make
> it go away.  Can someone tell me if this is normal?  Its so touchy I swear
> I'm going to switch those trimmers out for 10turns.
> I need to make certain the miniwave is working as close to perfectly as
> possible so I can debug the Minirom to make sure I built it right and more
> importantly wired it right...
> --
>  -----------------------------------------------------------------
>  - Tom Arnold       -  Free Synth DIY webspace http://www.sdiy.org
>  - SynthGeek        -  "...is it a virus, a drug, or a religion?"
>  - K6AET            -  Juanita Shrugs. "What's the difference?
>  --------------------         -- Neal Stephenson,  Snow Crash
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