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Subject: RE: [chromapolaris] assignable control footpedal

From: "Paul D. DeRocco" <pderocco@...>
Date: 2007-06-21

> From: spistrich
>
> Does anyone know of a suitable footpedal that will work for this . I
> tried a Roland ev-5 expression pedal, and it wasnt apparently very
> effective. (did a little modulation change but not what
> function it was
> selected to do). It seems that other footswitches do well for the
> sustain function, and metronome, but the assignable control needs
> something special.

It's nothing special, it just needs to be a variable resistance between ring
and tip, if it's a stereo plug, or sleeve and tip if it's a mono plug,
varying from zero to about 100K as you push the pedal down (away). If you
have minimal tools, you should be able to replace the pot inside an existing
pedal, and change the way its wired up if necessary.

The board has a 200K pull-up resistor to +12V, and the optimum range for the
A/D converter is a little under 5V, so 100K is perfect. However, some pedals
only rotate the pot through a fraction of the range, so in this case, you'd
need a higher value pot, maybe 250K.

Remember, also, there's a calibration procedure to teach the Polaris the
exact voltage range of the pedals and levers. If you have a low-value pot
that only runs the voltage from, say, zero to 1V, the calibration may still
work, but the result will be grainy since you only have 50 A/D converter
values to work with.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...