Air Horn Piano

My project, working title “Air Horn Piano” is something I’ve pondered on and vaguely planned for many, many years now. I’ve recently come across a 3D printable train horn design which can be easily tuned by adjusting the length of the PVC pipe between the printed sections.

A section of horn being 3D printed.

My good friend Sarah Tamsin has offered me time on her 3D printer before now, so now that I’ve located a tunable horn design, I’ve taken her up on that.

The rear section, with hose barb, and the back plate.

There are many, many air horn kits out there already for playing tunes, most notably Dixie horns, however, the aim of my project is to create a chromatic set of horns for playing any arbitrary tune or accompaniment I may want.

The horns will connect to 12V pneumatic solenoids, which will be triggered by 5V / 12V relays. When current reaches the 5V relay, the 12V solenoid will open. The 5V relays will be controlled by a Raspberry Pi, and software which I haven’t written just yet.

When open, air from a compressor and tank will be delivered to the horn, making a loud noise. Having played around with train horns before, I know from experience that a horn compressor alone will not be enough, so I’ve ordered a 120 PSI compressor & 6 litre tank combo.

My intention is to set up an interface to play MIDI files through the Pi and horns, and eventually, to connect a MIDI keyboard and make the horns directly playable.

More will follow on this project as it develops!

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