Step 8: Variations and Notes
- Build massive sensors
- Optimize the resistors and code for things that vibrate quickly, and use it as a pickup/microphone
- There are probably other tricks for decoupling the system from AC hum (a huge capacitor beteween the plates and the ground?)
- I've experimented with shielding the plates on the bottom, but it only seems to cause problems
- Make an RGB or HSB color picker
- Control video or music parameters; sequence a beat or melody
- Large, slightly bent surface with multiple plates + a projector = "Minority Report" interface
The Arduino playground has two articles on capacitive touch sensing (CapSense and CapacitiveSensor). In the end, I went with an inversion of a design I stumbled across in a friend's copy of "Physical Computing" (Sullivan/Igoe) describing how to use RCtime (the circuit had the capacitor and one resistor fixed, and measured the valueof a potentiometer).
The microsecond timing was accomplished using some slightly optimized code from the Arduino forums.
Again: just from starting at tons of theremin schematics I don't completely understand, I'm well aware there are better ways to do capacitive distance sensing, but I wanted to make something as simple as possible that's still functional. If you have an equally simple and functional design, post it in the comments!
Thanks to Dane Kouttron for tolerating all my basic electronics questions and helping me understand how a simple heterodyne theremin circuit works (originally, I was going to use these -- and, if tuned correctly, it would probably be more accurate).