Percussion ribbon controller

Byron G. Jacquot thescum at surfree.com
Thu Nov 11 03:52:06 CET 1999


>Has anybody out there ever seen plans for a ribbon 
>controller that you operate like a drum, so that you get 
>different notes depending on where you hit it? I am 
>thinking of something about two feet long that covers maybe 
>two octaves of range. Absolute pitch is not an issue. Some 
>type of robust resistive element perhaps?

I built one that comes close, but never got it entirely tweaked.  But I can
fill in a few details.

I used one of those black bags that pentium chips come in as the resistive
element.  I just cut a long, narrow strip out of the bag.  If you want a
really long strip, make the cut a sipral that goes around the bag.

I glued it to a strip of plexiglass, and wrapped the ends of the bag over
the the ends of the plexi, so it was around the back surface a little bit.
I then bolted the plexi onto a scrap of lumber, and on those wrapped-under
egdes of the bag, I placed a wire at each end.  The pressure from the screws
held the bag and the wire together.  One wire went to ground, the other to 5V.

Above the bag, I suspended a piece of picture framing wire from eyescrews.
(My description isn't too great...think of a strip of lumber, with the wire
running the length, like a guitar string.  The bag was underneath most of
the length of the wire).  From this I was able to get a variable voltage
while I held the wire down.  The framing wire was also tied to ground with a
10K resistor.

I ran the output of the framing wire through a S&H circuit, with the clock
for the S&H coming from a comparator that also watched the framing wire.  I
never got the S&H working the way I wanted...it was just too touchy.  I'm
sure there are some good ones floating around, tho.

It might also be cool with a track and hold.

And a note on the framing wire: it oxidizes and gets unresponsive quickly.
Better wire might be in order, or keeping some steel wool handy to polish it
before use.  Also, the signal coming from the wire was fairly dirty.  You
might run it through a touch of lowpass (or turn up the glide on the synth
you're controlling).

Byron Jacquot





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