ComputerVoltageSources

I've interfaced my Kurzweil Expressionmate through my PSIM to provide
a ribbon controller and later designed a module using an
AtomPro24 as a dedicated Expressionmate ribbon module.

I just recently bought a Kurzweil PC-2 which is just the passive
ribbon from Sweetwater for $50. It came today and I've written a small
program on the PSIM to control it. The PSIM inputs are 100K to ground.
I drive the ribbon 'potentiometers' from a CV output of 5.6 volts and
put a diode drop to ground. This floats the ribbon from 0.6 to 5.6
volts. If I read <0.6 volts from a ribbon section then there is no
contact. That way I can detect ribbon contact to generate a gate
signal. Right now I am just piecing the three ribbon sections back
together for a continuous output of 0 to +10 volts.

I'm using three inputs (to read the three ribbon sections) and three
outputs (5.6 volts, gate out, and CV out).

I need to come up with a better wiring scheme than this mess of cables
and then I'll wire it into a VCO to see how smooth it is. I haven't
really calibrated the min and max voltages and the offsets for the
three sections but I assume I can get it reasonably smooth.

With the larger number of outputs from the current design I could have
1, 2, or 3 ribbons each with a gate and trigger output.

I put a schematic of the ribbon cable pin out on my site
http://modularsynthesis.com/modules/DJB-011/djb011.htm

Dave

I'm running the Doepfer ribbon right now... It has a surface
finish that is a little sticky to my touch. I put a piece of
UHMW Polyethylene tape over it and it improved it a lot.

The pressure sensitivity leaves a LOT to be desired... I'm zener
clamping it at 5V... below that it has a lot of noise if you are
sliding.
OTOH into my 'moog clone' (an EFM VCO3 and VCF2e) it gives a growly
sound that is ~not~ unpleasant

I added a filter circuit to the pressure... it helps a little bit.

Looks like it needs to have a method to latch the last note played...
could be tricky to do. Hey WAIT... the Moog single contact S/H
scheme should work fine !!! (I amaze myself sometimes :^)

I have some FSR ribbon pressure strips... When I try the Kurzweil I'll
have to see if I can adapt one of them to emulate the Doepfer.

BTW I have the ~old~ Doepfer pressure sensor... its not really very
good.
I hear the new one is MUCH better...

H^) harry

djbrow54 wrote:

>
> I've interfaced my Kurzweil Expressionmate through my PSIM to provide
> a ribbon controller and later designed a module using an
> AtomPro24 as a dedicated Expressionmate ribbon module.
>
> I just recently bought a Kurzweil PC-2 which is just the passive
> ribbon from Sweetwater for $50. It came today and I've written a small
>
> program on the PSIM to control it. The PSIM inputs are 100K to ground.
>
> I drive the ribbon 'potentiometers' from a CV output of 5.6 volts and
> put a diode drop to ground. This floats the ribbon from 0.6 to 5.6
> volts. If I read <0.6 volts from a ribbon section then there is no
> contact. That way I can detect ribbon contact to generate a gate
> signal. Right now I am just piecing the three ribbon sections back
> together for a continuous output of 0 to +10 volts.
>
> I'm using three inputs (to read the three ribbon sections) and three
> outputs (5.6 volts, gate out, and CV out).
>
> I need to come up with a better wiring scheme than this mess of cables
>
> and then I'll wire it into a VCO to see how smooth it is. I haven't
> really calibrated the min and max voltages and the offsets for the
> three sections but I assume I can get it reasonably smooth.
>
> With the larger number of outputs from the current design I could have
>
> 1, 2, or 3 ribbons each with a gate and trigger output.
>
> I put a schematic of the ribbon cable pin out on my site
> http://modularsynthesis.com/modules/DJB-011/djb011.htm
>
> Dave
>
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