[sdiy] Kurzweil PC-2 ribbon controller

[David Brown]

At 09:57 PM 4/14/2006, David Brown wrote:
>Now to write a PSIM program for a single or triple ribbon 
>controller.  I think I will wire 100K resistors from the 'wipers' to 
>a voltage higher than across the resistors.  That way I can tell 
>whether the ribbon is in contact (output voltage between the 
>resistor voltage) or not in contact (output voltage higher than the 
>resistor voltage).  I'm thinking that just a diode drop would do.  I 
>can run the ribbon off of +5.7 volts with each section at +5 
>volts.  That way I can do a return to center and know when to output a gate.

I went the other way.  I added a diode in series with the ground 
connection. This limits the lowest voltage I can generate with the 
ribbon to 0.6 volts.  I rely upon the input impedance of the PSIM 
(100K) to read 0 volts when there is no contact with the ribbon. Works fine.

I've smoothed the transitions across the three ribbons.  It's not 
quite perfect but I'm not sure if you would notice if you didn't know 
where the transitions are.  It's at least as good as the Expressionmate.

Who else bought a PC-2?  Did you get your's yet?
Dave