Listen to This MIDI Keyboard-Controlled Slide Whistle Play 'Seven Nation Army'

After semi-successfully attempting to build a PVC reed instrument, YouTuber “The Mixed Signal” decided to go a slightly different direction, creating a PVC instrument based on a fipple. The fipple, found on instruments like recorders and slide whistles, manipulates air flow in such a way as to produce audible vibrations. The pitch can then be modified by changing the effective length of the instrument’s tube.

This is normally done by covering air holes, or sliding a piston, and this piston action can be accomplished fairly easily with a linear actuator. To do this, ‘Signal implemented a rack-and-pinion system with a stepper motor to adjust the length according to MIDI input from a keyboard, and a centrifugal fan to provide air flow. A slight modification was needed to reduce the pinion’s diameter in order to avoid overloading it torque-wise, but (after the fact at least) it seems like a pretty straightforward build.

The keyboard is hooked up to an Arduino Due, which actuates the slide via a CNC shield. The Due is especially well-suited to this type of musical application, as it can take advantage of its native USB port for control. Lots more details can be found on the project write-up, as well as in the video above.