In its final form, it is a 19 note semi-automatic instrument based on standard Hohner harmonica reed plates. Its sound is most like a Melodica and its heritage is similar to the old automatic Pianolas popular in wild west movies. Music song "Rolls" are created on a mobile app using a standard Harmonica tab format, this is then sent via Bluetooth to the device where it mechanically sets up the correct notes to be played by opening and closing air outlet valves at the request of the musician. The musician then blows or draws into the instrument to create the note, then releases a button to automatically select the next correct note. Unlike a pianola, the Renzonica does not seek to remove the musician from the performance, it instead simply removes the burden of having to remember the notes to play.
I'm friends with a startup, Seguel Robotics, that supplies STEM projects to disadvantaged schools here in Chile. They have a great controller, the Brainbox , an ESP32 based board that is Arduino compatible has wifi, Bluetooth, some inbuilt buttons 25 RGB LED display and can control servos well. So it was a logical choice for the brains of the Renzonica. I wrote the main code for creating songs in an Android app for mobile phones that then sends the songs to the Brainbox via Bluetooth. The brainbox then displays the song and controls 5 servos that are linked via rods and levers that close off the holes in an air manifold. The design was modelled first in a 3d package. The main body is laser cut out of acrylic and wood and the prototypes were built using a Formlabs 3d printer. The final version was professionally 3d printed by Shapeways. Whilst we began the project trying to make our own reeds also, this proved to be very difficult and we started to admire and appreciate the craftsmanship that still goes into standard Hohner harmonica reed plates. So the Renzonica currently uses 2 Hohner harmonica marine band plates in C.
Perseverance is everything. A one year project soon became a five-year project with many wrong directions along the way. At first, we tried to create our own reeds, before deciding to base it on a standard Hohner harmonica. Then we experimented for a long time with homemade air valves, but controlling air going into the harmonica body proved troublesome. Eventually, we settled on a Melodica inspired design, where you control the air valves on exiting after the reeds (the opposite of a harmonica) These valves are controlled by 5 servos rotating in opposite directions to control 10 valves in total to give 19 notes via drawing and blowing on the instrument (1 note is duplicated on harmonica reeds)
I wanted to also make a useful mobile application to create songs for the Renzonica. A phone is easy to carry around than a PC so it made a lot of sense. I make games for a living so this was also relatively easy to achieve. I was inspired by a game called Piano Tiles but made something more functional. You can input Harmonica tabs, which is a common format for harmonica music. The numbers relate directly to the 10 holes you are blowing (+ve) or drawing (-ve) on the harmonica. The one problem is there is no timing information in that notation, so I allow you to add a "performance" and then generate standard music notation from that. This can be downloaded to the Renzonica via Bluetooth instantly in the Renzonicas own format. What I found interesting is its also useful for learning and playing a normal harmonica so I put in an option to use it for that and will publish a version on Google Play soon if you want to try it out.