learning the ropes

things I made at ITP and after: sketches, prototypes, and other documentation

Wednesday, April 29, 2009

Drawing Tool Holder Prototype #1

One thing I’ve been trying to work out is how to turn the sound on and off.  For testing purposes, I’ve been using a footswitch that I step on whenever I start drawing.  As I’ve been making larger drawings, the ropes have pulled the footswitch away from me. 

Originally, I was planning to use a piezo-based contact mic mounted to the drawing surface to pick up the sound of the drawing tool, but my initial experiments with this technique did not yield good results.  Although techniques I found for interfacing a piezo element with Arduino don’t include an amplifier, I have a feeling it will be necessary to boost the signal coming out of the piezo.  I tried several piezo elements I had laying around — including a known good one, but I couldn’t get reliable data from it.

Hal suggested in his response to my post the other day that I might want to consider a pressure sensor, so today I’ve been prototyping a drawing tool holder which uses a force sensistive resistor to determine how hard I’m pressing the drawing tool against the drawing surface.
tool holder

IMG_1425 IMG_1426

My first attempt needs some refinement, though.  There needs to be a spring mechanism inside (like a click ballpoint pen has) to keep the drawing tool off of the sensor when I’m not drawing.  In this first prototype, I used some packaging foam to hold the drawing tool in place.  The undesired side effect is that the foam also holds the drawing tool securely against the force sensing resistor, so this prototype would never be able to tell me when the drawing tool is lifted.

posted by Michael at 3:37 pm  

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