A MIDI Harmonica

MIDI, or Musical Instrument Digital Interface, has been the standard for computer control of musical instruments since the 1980s. It is most often associated with electronic instruments such as synthesisers, drum machines, or samplers, but there is nothing to stop it being applied to almost any instrument when combined with the appropriate hardware.

[phearl3ss1] pushes this to the limit by adding MIDI to the most unlikely of instruments. A harmonica might seem to be the ultimate in analogue music, yet he’s created an ingenious Arduino-powered mechanism to play one under MIDI control.

The harmonica itself is mounted on a drawer slide coupled to a wheel taken from a pool sweeper and powered by a motor  that can move the instrument from side to side with a potentiometer providing positional feedback to form a simple servo. The air supply comes from a set of three bellows driven via a crank from another motor, and is delivered by what looks like a piece of PVC pipe to the business end of the harmonica.

The result is definitely a playable MIDI harmonica, though it doesn’t quite catch the essence of the human-played instrument. Judge for yourselves, he’s posted a build video which we’ve placed below the break.

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Hackaday Prize Entry: Electronic, Visual Harmonicas

[sholnkin] is tasked with teaching a kindergarten class how to play a musical instrument. No, not those cheap plastic recorders. [shlonkin] is teaching kindergarteners how to play the only instrument that both blows and sucks: the harmonica.

Unlike a classroom of kids with plastic recorders, where the fingering is either right or it isn’t, [shlonkin] needs to teach kids to put their mouth over the right hole, and suck or blow to produce a note. The classroom has a poster laying out the notes on the harmonica, but they needed something better. [shlonkin] envisioned a large illuminated sign that lit up in different colors, and could play the displayed notes with a speaker.

The high-level design for this project includes a Teensy 3.2 with the Audio Adapter breakout driving a small audio amp. The Teensy also controls a bunch of LEDs mounted inside a wooden case. The layout of these LEDs went surprisingly well, and it’s rare to find a backlit panel that is lit this evenly.

As a classroom musical teaching aid, this type of device has been around for decades – deep in the recesses of band rooms in schools across the world, you can find old Wurlitzer pianos with devices that aren’t much different from this simple device. It’s a pedagogical method that worked back then, and should work now.

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Hackaday Prize Entry: Harmonicas, Candy, And Van Halen

Watch enough How It’s Made, and you’ll soon become very enthusiastic about computer vision and compressed air. In factories all around the world, production lines automatically sort the wheat from the chaff by running a product underneath a camera and blowing defective product off the line.

For his Hackaday Prize entry, [Fabien] is attempting this same task. He’s building a machine that will rapidly sort candy with computer vision and precisely controlled jets of air. He’s also planning for the Van Halen reunion and building a CNC harmonica.

Right now, the design has a hopper full of M&Ms dropping through a channel where a camera looks at each individual piece of candy. A Raspberry Pi, camera, and OpenMV detect all the red, yellow, brown, and blue M&Ms, and send that information to a computer controlling a suite of pneumatic valves. When these valves open, candy of different colors is shuffled off into it’s own bin. It’s the perfect device for someone responsible for reading Van Halen’s rider.

In an interesting little side project, [Fabien] needed a way to test the pneumatic valves before building the color sensor and candy chute. He had a harmonica lying around, and built something we’re surprised we’ve never seen before. It’s a CNC harmonica, capable of belting out a few tunes. You can check out that testing video after the break.

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Automatic Pneumatic Harmonica

A wise man once said “If all you’ve got is a cute desktop compressor and some solenoid valves, everything looks like a robotic harmonica.” Or maybe we’re paraphrasing. Regardless, [Fabien-Chouteau] built a pneumatic, automatic harmonica music machine.

It’s actually an offshoot of his other project, a high-speed candy sorting machine. There, he’s trying to outdo the more common color-sensor-and-servo style contraptions by using computer vision for the color detection and a number of compressed-air jets to blow the candy off of a conveyor belt into the proper bins.

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The 8 Bit Harmonica Blows In From Japan


From [Basami Sentaku] in Japan comes this 8bit harmonica. [Basami] must remember those golden days of playing Famicom (or Nintendo Entertainment System for non-Japanese players). As the systems aged, the contacts would spread. In the case of the NES, this would often mean the infamous blinking red power light. The solution for millions of players was simple. Take the cartridge out, blow on it, say a few incantations, and try again. In retrospect, blowing on the cartridges probably did more harm than good, but it seemed like a good idea at the time. We’d always assumed that the Famicom, being a top loading design, was immune from the issues that plagued the horizontal slot on the NES. Either [Basami] spent some time overseas, or he too took to tooting his own cartridge.

Blowing into cartridges has inspired a few crafty souls to stuff real harmonicas into cartridge cases. [Basami] took a more electronic route. A row of 8 microphones picks up the players breath sound. Each microphone is used to trigger a specific note. The katakana in the video shows the traditional Solfège musical scale: do, re, mi, fa, so, la ti, do. A microcontroller monitors the signal from each microphone and determines which one is being triggered. The actual sound is created by a Yamaha YMZ294. The ‘294 is an 18 pin variant of the venerable General Instrument AY-3-8910, a chip long associated with video game music and sound effects. While we’re not convinced that the rendition of Super Mario Bros’ water theme played in the video wasn’t pre-recorded, we are reasonably sure that the hardware is capable of doing everything the video shows.

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