A wooden xylophone with electronic contraptions for robotic playback

Robotic Xylophone Makes Music With MIDI Magic

January 27, 2022 by 8 Comments

The MIDI format has long been used to create some banging electronic music, so it’s refreshing to see how [John P. Miller] applied the standard in his decidedly analog self-playing robotic xylophone.

Framed inside a fetching Red Oak enclosure, the 25-key instrument uses individual solenoids for each key, meaning that it has no problem striking multiple bars simultaneously. This extra fidelity really helps in reproducing the familiar melodies via the MIDI format. The tracks themselves can be loaded onto the device via SD card, and selected for playback with character LCD and rotary knob.

The software transposes the full MIDI music spectrum of a particular track into a 25-note version compatible with the xylophone. Considering that a piano typically has 88 keys, some musical concessions are needed to produce a recognizable playback, but overall it’s an enjoyable musical experience.

Perhaps most remarkable about this project is the documentation. If you want to build your own, everything you need to know is available online, and the no-solder approach makes this project very accessible. Most of the write-up happened some years ago, and we’re really interested to see what improvements have been made since.

The robotic xylophone is reminiscent of these automatic tubular bells from some time ago. These musical hacks can be particularly inspiring, and we can’t wait to see more.

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Guitar Pickguard Adds MIDI Capabilities

December 6, 2021 by 1 Comment

For a standard that has been in use since the 1980s, MIDI is still one of the most dominant forces on the musical scene even today. It’s fast, flexible, and offers a standard recognized industry-wide over many different types of electronic instruments. Even things which aren’t instruments can be turned into musical devices like the infamous banana keyboard via the magic of MIDI, and it also allows augmentation of standard instruments with other capabilities like this guitar with a MIDI interface built into the pick guard.

[Ezra] is the creator of this unique musical instrument which adds quite a few capabilities to his guitar. The setup is fairly straightforward: twelve wires run to the pick guard which are set up as capacitive sensors and correspond with a note on the chromatic scale. Instead of using touchpads, using wires allows him to bend away the “notes” that he doesn’t need for any particular piece of music. The wires are tied back to an Adafruit Feather 32u4 microcontroller behind the neck of the guitar which also has a few selectors for changing the way that the device creates tones. He can set the interface to emit single notes or continuously play notes, change the style, can change their octave, and plenty of other features as well.

One of the goals of this project was to increase a guitar player’s versatility when doing live performances, and we would have to agree that this gives a musician a much wider range of abilities without otherwise needing a lot of complex or expensive equipment on stage. We’ve seen a few other MIDI-based builds focused on live performances lately, too, like this one which allows a band to stay in sync with each other.

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This is a MIDI harp that is played by waving your hands in the air over the infrared distance sensors.

Teensy MIDI Air Harp Sounds Huge

November 15, 2021 by 4 Comments

Some of the coolest sounds come from wild instruments like orchestra strings, fretless basses, and theremins — instruments that aren’t tied down by the constraints of frets and other kinds of note boundaries. [XenonJohn]’s air harp is definitely among this class of music makers, all of which require a certain level of manual finesse to play well.

Although inspired by Jean-Michel Jarre’s laser harp, there are no lasers here. This is a MIDI aetherharp, aka an air harp, and it is played by interrupting the signals from a set of eight infrared distance sensors. These sensors can be played at three different heights for a total of 24 notes, plus there’s a little joystick for doing pitch bends.

Inside the wooden enclosure of this aetherharp is a Teensy 3.5 and eight infrared distance sensors with particularly long ranges. On top is a layer of red acrylic that doesn’t affect the playability, except in bright sunlight. Although you could use most any MIDI software to produce the actual sounds, [XenonJohn] chose VMPK (Virtual MIDI Piano Keyboard). Be sure to check it out in action after the break.

Not dangerous enough for you? Here’s a laser harp that involves a Tesla coil.

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Recharged Dehumidifier Put Back Into Service

September 19, 2021 by 39 Comments

For the average consumer, repairing relatively low-cost home devices such as microwaves and TVs just isn’t economically viable. You can hardly blame them when the repair bill could easily be higher than the cost of just buying a new model. Luckily for folks like us, that means you can often find cheap or even free appliances on the second hand market that can be brought back online with a bit of troubleshooting and some spare parts.

Take for example the non-functional dehumidifier [HowToLou] recently came across. You probably couldn’t find a professional repair shop that would be willing to bother with one of these things if you tried, but as he shows in the video below, that doesn’t mean the DIY’er can’t run through some probable failure modes and get the unit back up and running. As a bonus, he also walks viewers through how your typical compressor-based dehumidifier operates.

The failed thermal switch.

Beyond the lack of water in the collection compartment, the first sign that something was wrong with this dehumidifier was that the compressor wasn’t running. Upon closer inspection, [HowToLou] determined that the thermal cut-off switch had failed and was stuck open. Luckily it had a visible part number so he could order a replacement, and in the meantime, all he had to do was cut the switch out of the circuit and wire up the compressor’s power directly.

Unfortunately, even with the compressor running, no water was being collected. Noticing that the evaporator coils weren’t getting very cold, [HowToLou] thought the unit might be low on refrigerant. Usually these systems aren’t meant to be recharged, but with a clever piercing tap valve, you can add a quick-connect port to the low pressure side. This particular dehumidifier happened to be filled with the same R134a used in automotive A/C systems, so a quick trip to the auto parts store got him a can of refrigerant complete with a handy pressure gauge.

After getting juiced up, [HowToLou] shows ice forming on the coils and plenty of water getting dumped into the tank. Automotive A/C refill cans usually include some substance to stop or reduce leaks in the system, so hopefully this will end up being a long-term fix. It might not be the most elaborate dehumidifier repair we’ve ever seen, but it’s certainly the most approachable. If you ever see one of these things laying on the side of the road, maybe you should pick it up and see what ails it.

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A musical cyberdeck

Musical Cyberdeck Is Part Synth, Part MIDI Controller, And All Cool

September 9, 2021 by 3 Comments

When a new project type starts to get a lot of exposure, it’s typically not long before we see people forking the basic concept and striking out in a new direction. It happened with POV displays, it happened with Nixie clocks, and now, it seems to be happening with cyberdecks. And that’s something we can get behind, especially with cyberdecks built to suit a specialized task, like this musical cyberdeck/synth.

Like many musicians, [Benjamin Caccia] felt like he needed a tool to help while performing with his band “Big Time Kill.” He mainly needed to trigger track playbacks on the fly, but also wanted something to act as a mega-effects pedal and standalone synth. And while most of that could be done with an iPad, it wouldn’t look as cool as a cyberdeck. The build centers around a Raspberry Pi 4 and a 7″ LCD display. Those sit on top of a 25-key USB MIDI keyboard and a small mixer. Alongside the keyboard is a USB keypad, which has custom mappings to allow fast access to buried menu functions in the cyberdeck’s Patchbox OS. Everythign was tied together on a 3D-printed frame; the video below shows it in action, and that it sounds as good as it looks.

We think [Benjamin]’s cyberdeck came out great. Need to see some other specialized cyberdecks? Why not take a look at this battle-ready cyberdeck, one that aims to be distraction-free, or a cyberdeck for patrolling the radioactive wastelands.

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MIDI Mouse Makes Marvelous Music

July 18, 2021 by 5 Comments

It’s an old misconception that digital musicians just use a mouse and keyboard for their art. This is often far from the truth, as many computer music artists have a wide variety of keyboards/synths, MIDI controllers, and “analog” instruments that all get used in their creative process. But what if one of those instruments was just a mouse?

Well, that must have been what was going through [kzra]’s mind when he turned an old ps/2 roller ball mouse into an electronic instrument. Born out of a love for music and a hate for waste, the mouse is a fully functional MIDI controller. Note pitch is mapped to the x-coordinate of the pointer, and volume (known as velocity, in MIDI-speak) is mapped to the y-coordinate. The scroll wheel can be used as a mod wheel, user-configurable but most often used to vary the note’s pitch. The mouse buttons are used to play notes, and can behave slightly differently depending on the mode the instrument is set to.

Not satisfied with simply outputting MIDI notes, [kzra] also designed an intuitive user interface to go along with the mouse. A nice little OLED displays the mode, volume, note, and mouse coordinates, and an 8×8 LED matrix also indicates the note and volume. It’s a fantastic and versatile little instrument, and you’ve gotta check out the video after the break to see it for yourself. We’ve seen some awesome retro-tech MIDI controllers before, and this fits right in.

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MIT’s Knitted Keyboard Is Quite A Flexible MIDI Controller

June 30, 2021 by 7 Comments

There are only so many ways to make noise on standard instruments such as acoustic pianos. Their rigidity and inputs just don’t allow for a super-wide range of expression. On the other hand, if you knit your interface together, the possibilities are nearly endless. MIT’s new and improved knitted keyboard is an instrument like none other — it responds to touch, pressure, and continuous proximity, meaning that you can play it like a keyboard, a theremin, and something that is somewhere in between the two. Because it’s a MIDI interface, it can ultimately sound like any instrument you’ve got available in software.

The silver keys of this five-octave interface are made of conductive yarn, and the blue background is regular polyester yarn. Underneath that is a conductive knit layer to complete the key circuits, and a piezo-resistive knit layer that responds to pressure and stretch. It runs on a Teensy 4.0 and uses five MPR121 proximity/touch controllers, one per octave.

The really exciting thing about this keyboard is its musical (and physical) versatility. As you might expect, the keyboard takes discrete inputs from keystrokes, but it also takes continuous input from hovering and waving via the proximity sensors, and goes even further by taking physical input from squeezing, pulling, stretching, and twisting the conductive yarns that make up the keys. This means it takes aftertouch (pressure applied after initial contact) into account —  something that isn’t possible with most regular instruments. And since this keyboard is mostly yarn and fabric, you can roll it up and take it anywhere, or wrap it around your neck for a varied soundscape.

If you’re looking for more detail, check out the paper for the previous version (PDF), which also used thermochromic yarn to show different colors for various modes of play using a heating element. With the new version, [Irmandy Wicaksono] and team sought to improve the sensing modalities, knitted aesthetics, and the overall tactility of the keyboard. We love both versions! Be sure to check it out after the break.

Want to play around with capacitive touch sensors without leaving the house for parts? Make your own from paper and aluminum foil.

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