Should you strive arduous sufficient, absolutely anything may be coerced into making music. From the clatter of kitchen utensils and the percussive slap of naked arms on a tabletop, to the resonant twang of a rubber band stretched throughout a tin can, the potential for sound is common. The principle ingredient wanted to create a novel musical instrument is creativity.
Think about Redditor Zip_ties_and_psi’s odd mechanical MIDI orchestra, as an illustration. What started as a easy experiment in abusing electromechanical {hardware} become a surprisingly good relay-based MIDI participant. The concept is easy sufficient: take the clacking of fast-switching relays and form it right into a sequence of musical notes. However executing on that plan took a variety of effort. Oh, and one observe — for those who care about your relays in any respect, don’t put them by this sort of abuse.
The instrument is constructed round an LC ESP32 Relay X8 board, a compact module that pairs an ESP32 microcontroller with eight onboard mechanical relays. Whereas relays are usually supposed for gradual, rare switching, this venture pushes them to their limits, driving them at anyplace from 50 to 150 Hz. Every relay turns into a “voice” in an eight-note mechanical synth, with completely different relays tuned to completely different buzz frequencies. When a number of relays are energized concurrently, the ensuing cluster of clicks and buzzes varieties a chord.
To make this work, the ESP32 itself doesn’t interpret MIDI straight. As a substitute, a Python script on a PC handles the heavy lifting. Utilizing the mido library, the script ingests a normal MIDI file, calculates timing based mostly on the file’s tempo, and tracks which musical notes are energetic at any second. These notes are then mapped into eight frequency “bins,” every similar to a relay. The script outputs a protracted listing of mask-and-duration pairs, successfully describing which relays ought to be energetic and for a way lengthy. This information is pasted straight into the primary Arduino sketch as a C++ array.
As soon as flashed, the ESP32 boots into access-point mode beneath the title “RelayMidi.” A easy net interface supplies Play, Cease, and speed-adjustment controls. Because the ESP32 cycles by the music information, it quickly toggles relays in response to the masks, turning the delicate parts right into a rhythmic percussion part that may chug alongside for so long as they survive.
It’s loud, impractical, and undoubtedly not relay-friendly, however as a reminder of how far creativity can stretch easy {hardware}, this clattering contraption is tough to beat.
