ComputerVoltageSources

The Kurzweil ribbon is actually three independent ribbon segments.

One CVS output is for 5.6 volts to power the ribbon. I use a diode 
drop in the bottom leg so the ribbon output is 0.6 to 5.6 volts. That 
way I can detect 0 volts which means no contact with the ribbon. The 
other three outputs are CV, Trigger, and Gate.

Three of the inputs are used for each of the ribbon sections. The 
middle ribbon is backwards so the software reverses the middle and 
pieces back the sections. I have a constant that I adjust to match the 
voltage drop of the diode and the piecewise continutity of the ribbon 
is pretty good.  There are just very slight discontinuities as you 
switch from ribbon to ribbon.

The fourth input is optional and is used with a potentiometer to 
control offset.  I generally run the output of my ribbon to an offset 
module which will generate +/- 5 volts from the 0 to 10 volt output. 
The conversion is not perfect, so this offset allows me to 'dial' in 0 
at the exact center of the ribbon. For example, if I'm using the 
ribbon to FM an oscillator, I can press on the center of the ribbon, 
and dial in no modulation by listening to the oscillator. In a 
dedicated setup, this could be a software constant but I left it in.

Of course modifying the software could give you three independant 
ribbons. You could add the second DAC and control circuitry to provide 
three independant CV, Trigger, and Gate outputs.

Dave

--- In ComputerVoltageSources@yahoogroups.com, "Larry T." <larry@...> 
wrote:
>
> Dave
> 
> I curious why you have populated 4 input channels?  What is the 
output
> from the Kurzweil PC-2 controller?  Could you actually populate even
> less on the board for this dedicated use?  I also noted the use of 
the
> AtomPro 24 instead of the 28, good idea for this dedicated use.
> 
> Larry T.
> 
> --- In ComputerVoltageSources@yahoogroups.com, "djbrow54" <davebr@>
> wrote:
> >
> > No one has mentioned a ribbon controller application. I have done 
a 
> > program that interfaces the Kurzweil PC-2 ribbon to my PSIM and it 
> > works pretty good. I bought my ribbon from Sweetwater for $50.  I 
> > assume they still have them.
> > 
> > The program outputs are a CV, trigger, and gate. This can be built 
in 
> > a depopulated CVS pcb and there is a photo in my photo album 
called 
> > "CVS special build configuration". I've got a second ribbon that I 
was 
> > going to use this PCB for, but haven't quite finished yet. Contact 
me 
> > for details if you are interested in building a CVS for a ribbon 
> > controller.
> > 
> > Dave
> >
>