I’m experimenting with ways of tuning the pipe on the twitterer project so that I can hopefully create a bird box automata where the bird sings a song with changing notes.
I’ve tried two different ways of tuning the pipe. Firstly, with an outer sleeve that moves back and forth, this works in the same way as a trombone hanging the length of an open ended pipe. It works fine and the pitch changes maybe five or six semitones between the extremes of travel.
My other option was to use an inner piece that worked as a piston. This inner tube is blocked off at the end inside the main pipe. As it moves it changes the length of the closed pipe. It work really well and has over an octave of pitch change between its extremities. This is the option I’m going with, next to connect it up and move it via a cam shaft.