Wednesday, January 13, 2010

The Trombone Controller Sings - accompanied by $38 worth of fail

Tonight I made another baby step with the trombone controller. I got the slide sensor (see FAIL* below) and the breath controller both working, mounted on the instrument, and added an RJ-45 connector so I can hook the thing up to the Arduino via an Ethernet cable, unclamp it from the workbench, and pick it up and play it. So, for the first time, I was able to get a feel for how playable this thing will be.

I was pleasantly surprised. While there are a lot of glitches, I felt like I was able to be expressive on the instrument. Here's a video:

The whole air pressure system is made from garden drip irrigation tubing I had laying around. I really hope it's non-toxic.

*FAIL (or, how to blow up a $27 linear potentiometer and an $11 pressure sensor)

In my quest to make all the pieces of my new instrument modular, I decided that I would terminate each sensor in some sort of connector that could be plugged/unplugged to assemble new, unanticipated instruments. Well...
  • Don't use 1/8" stereo phono jacks for anything carrying Vcc. They short as they're being plugged/unplugged, which (thank you, Arduino designers) doesn't make the magic smoke come out of the Arduino, but it does make your Mac grumpy with the excessive current on the USB bus - but no Mac damage either (thank you, Mac designers).
  • Measure (er, check wiring) twice. Or maybe 5 or 6 times. I managed to wire 5v across the wrong two leads of my quite expensive SpectraSymbol SoftPot, and now when no pressure is applied, the output lead floats. Well, at least Mouser Electronics gets something out of this. :-(
  • Freescale Pressure Sensors don't care that your low-wattage soldering iron sucks and won't melt solder and you pulled out the big iron to solder the sensor to a perfboard. Moral of the story: socket everything in a prototype!

1 comment:

  1. As it turns out, I didn't burn out the 500mm linear pot (but I did melt the pressure sensor).