Resonance Tube is an exhibit in the Wonder Why exhibition at Liberty Science Center. When I joined LSC the sound had issues of static, popping, and cutting out. Also the knobs would come loose or break as guests would force the potentiometers past their stop points. LSC was curious if the pots could be changed out for magnetic rotary encoders. The particular ones they found would not wear out as easily and didn’t have stop points so guests could spin them around endlessly without causing damage.

The only thing was the pots in the circuit could not be directly swapped for these magnetic rotary encoders. I thought this could be a good opportunity to change out the preexisting analog circuit for an MCU which not only could easily work with the new encoders, but would allow us wider and easier control of the produced output. By choosing an MCU w/ a DAC, I could in code quickly and easily change the mapping of knobs to volume and pitch. Here’s the exhibit now running on a Teensy 3.5 I had available:

We were all happy with the improvement in sound quality, and the significantly increased visual response of the tube. All with the added benefit of the knobs not needed frequent repair. The code running on the Teensy can be found here: https://github.com/bobparadiso/LSC_ResonanceTube