Auto Xylophone Uses Homemade Solenoids

Want to play the xylophone but don’t want to learn how? [Rachad]’s automatic xylophone might be just the ticket. It uses homemade solenoids to play tunes under computer control. Think of it as a player piano but with electromagnetic strikers instead of piano keys. You can hear the instrument in action in the video below.

Since the project required 24 solenoids, [Rachad] decided to build custom ones using coils of wire and nails. We were amused to see a common curling iron used as an alternate way to apply hot glue when building the coils. The other interesting part of the project was the software. He now uses a toolchain to convert MIDI files into a serial output read by the Arduino. Eventually, he wants to train an AI to read sheet music, but that’s down the road, apparently.

Honestly, we were a bit surprised that it sounded pretty good because we understand that the material used to strike the xylophone and the exact position of the strike makes a difference. We doubt any orchestra will be building one of these, but it doesn’t sound bad to us.

The last one of these we saw did have more conventional strikers if you want to compare. Honestly, we might have just bought the solenoids off the shelf but, then again, we don’t make our own relays either.

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A wooden xylophone with electronic contraptions for robotic playback

Robotic Xylophone Makes Music With MIDI Magic

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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Robotic Glockenspiel Crunches “Popcorn”

[James] sent us a video of his latest creation: a robotic glockenspiel that’s currently set up to play “Popcorn”. It uses eight servos to drive mallets that strike the tone bars with fast, crisp movements. The servos are driven with a 16-channel I²C servo driver and MIDI shield, which are in turn controlled with an Arduino Uno. The previous incarnation of his autoglockenspiel employed solenoids, dowels, and elastic bands.

[Gershon Kingsley]’s 1969 composition for synthesizer “Popcorn” has been covered by many artists over the years, though perhaps the most popular cut was [Hot Butter]’s 1972 release. Check it out after the break, and dig that lovely cable management. We’d love to see [James]’s autoglockenspiel play “Flight of the Bumblebee” next.

If you’re hungry for more electro-acoustic creations, have a gander at [Aaron Sherwood]’s Magnetophone.

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A Doorbell Pleasing To Both The Ears And Eyes


When [David] moved into his new house, one of the things he noticed was that his doorbell was pretty lame. Coming from a home equipped with a solenoid and chime bell, his new wireless solid state doorbell sounded terrible to him.

Crummy sound aside, the doorbell hardly ever worked properly, but alas, other projects cropped up and years went by before [David] addressed his doorbell problem. Like many things that take a long time to come to fruition, we think his resonator bell based solution was well worth the wait.

One of his main goals was to make a nice sounding doorbell that also looked great. He mounted a kid’s resonator bell toy on a sheet of wood, creating his own wooden mallets for the job. He initially had a tough time locating actuators for his doorbell, but found a solution in geared pager motors as featured in another xylophone hack on Make. With the hardware taken care of he focused on the electronics, which consist of a pair of Arduino clones – one on the display and one in his basement.

Stick around to see [David’s] Campanello doorbell in action, and be sure to check out his site for more details if this sounds like something you would like to have in your home.

[via Make]

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Make Your Own Solenoids, Then Play The Xylophone

Learn to manufacture your own solenoids and then use them to play the xylophone by watching the tutorial video after the break. [Humberto Evans] and the team at Nerd Kits do a great job of not only manufacturing the coils, but the xylophone itself. The bars are machined from some aluminum stock and they take you down the rabbit hole with they why’s and how’s of engineering the keys.

We’re unlikely to replicate this machining process but the solenoids are another story all together. Starting at about 3:30 you can learn about designing, building, and using these little marvels. They’re basically an electromagnetic cuff with a metal slug in the middle. The solenoid seen above uses a body milled from HDPE and wrapped with magnet wire. The slug in the center is steel, with a few rare-earth magnets at the top. When you run current through the coil it repulses the magnets on the slug, witch then strikes the xylophone key. Using a MOSFET and a protection diode, actuating them is as simple as sending a digital high from your microcontroller of choice.

We’ve seen solenoids used to play a vibrophone before, but those were commercial units. Making your own hardware is far more hardcore.

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[Ania] wrote in to let us know her team had finished the Multixylophoniomnibus and that they have posted an extensive writeup about it. We covered this augmented xylophone when it was still in development at the beginning of this month. Originally they wanted to use mallets wrapped in tinfoil as switches that close when they contact the metal keys, something akin to matchbox cars as a switch. This plan was thwarted when they realized the paint surface insulated the metal keys. At this point they switched to piezo sensors which turned into an odyssey of trial and error to achieve a reliable input for the Arduino to monitor. In the end they got it working with around forty lines of code, interfacing six boxes containing a different type of noisemaker.

See the finished instrument played in the video after the break. Alas, the addition of the piezo sensors do impede the resonance of the xylophone keys, but we still like it! There’s something reminiscent of the beginning of Pink Floyd’s Money when this is played.

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Augmented Xylophone

[Ania’s] been working on extending a xylophone in a project called Multixylophoniomnibus. She’s fitted a piezo sensor on the bottom of each xylophone key, interfacing it with an Arduino. When a mallet hits a key the corresponding box augments the sound in one of several ways. It looks like she’s prototyped a box that twangs a rubber band, one that uses a solenoid to clap mini cymbals together, one that rattles a glass full of beads, another that vibrates a glass full of water, and yet another that rattles a chain.

It’s nice to see how versatile the xylophone is for instrument hacking. Her Flickr set is linked above but we’ve also embedded some prototyping videos after the break.

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