A new and improved magnetic cello

Over the past few months, [Magnetovore] has been working on his magnetic cell project. It’s a very interesting instrument that seems right out of the electronic music explosion of the 1970s. Now, he’s ready to share his invention with the world, and we wouldn’t be surprised if we see this instrument being picked up by a few avant-garde musicians in the next few years.

Last September, we were introduced to [Magnetovore]’s magnetic cello. The original version used four ribbon sensors for each of the strings and had completely analog electronics, leaving us wondering why this cello wasn’t invented in the 70s. The new version of the cello keeps the analog electronics that sound remarkably like a real acoustic cello, but does away with three of the ribbon sensors. Now the cello has a single ribbon sensor being used as all four strings – to change which string is played, the musician just has to press a button on the ‘bow’.

There is a drawback to using only one ribbon sensor; it’s now impossible to play two strings simultaneously as on an acoustic cello. The electronics in [Magnetovore]’s original magnetic cello were monophonic anyway, so we’ll chalk this design change-up to reducing component cost.

After the break, you can check out a trio of very talented cellists playing [Magnetovore]’s magnetic cello. There’s the classic Pokemon Center theme, the Mario Bros. theme, as well a Bach minuet and a crazy improvisation showing off what the magnetic cello can do.

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Barrel organ made from Lego plays the Star Wars theme

lego-starwars-barrel-organ

Whether or not you are a fan of the first installment of the Star Wars prequels, you have to see what [Lorenz Lnggrtnr] and [Renee Hoffmeister] have put together for the movie’s 3D debut.

In an attempt to capture the essence of Star Wars in a new fashion, they constructed a large barrel organ from Lego bricks that plays the movie’s legendary opening theme when turned. The barrel is separated into four parts, each representing one of the series’ iconic settings in plastic block form.

Hoth, the Death Star, Tatooine, and Endor are all featured on the organ, with each environment’s structures playing specific notes from the song. As the barrel turns each Lego structure toggles a note to be played on the attached organ, via a “reading” mechanism built from metal arms and Lego tires.

It looks fantastic, and sounds pretty decent too. Be sure to stick around for a short video that shows off the barrel organ in action.

[via Wired]

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Arduino MIDI sequencer displays a lot of data

This Arduino MIDI sequencer has no shortage of ways to display loop info. The screen above is a touch-sensitive interface that acts as the user input. But if this screen is not visible, you can still see which tracks have activated samples for each beat and what effects are being used. That’s thanks to the collection of display boards which are shown in the video after the break.

The setup acts as the MIDI front end, relying on other hardware to generate the samples. It presents all of the options through several pages on the 320×240 touch screen display. The Ardunio Mega is responsible for monitoring the UI data, crafting and sending the MIDI commands, as well as updating the LED-based display boards. These include bar graphs for the various effects, a four row by sixteen pixel beat pattern display, and 7-segment displays to track the current location within the loop. All in that’s 368 LEDs driven by 18 shift registers.

Update: Link to a gallery can be found after the break as well.

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Floppy drive as an audio sampler

Here’s a floppy drive which is being used as an audio sampler. At first glance we thought this was another offering which drives the stepper motor at a specific frequency to generate that characteristic sound at a target pitch. But that’s not what’s happening at all. The floppy is actually being used as a storage device (go figure).

From what we can tell, it’s being used almost like an 8-track tape. A PWM signal is stored on one circular slice of the disk, then the head can be moved back to that same “track” to play back the wave form. The head doesn’t move during playback, but just keeps reading the same track of bits. To the right you can see an Arduino board. This allows for MIDI control of the track selection. [Alexis] shows off some keyboard control in the video after the break. There’s a buffer chip on the breadboard which allows the audio output to be quickly switched off as the floppy drive head is moved. This keeps garbage out of the sound until the new track can be read.

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A "Jukebox" In a Bell Jar

jukebox in bell jar

[Tim] wrote in to tell us about his Mark III hard drive in a bell jar, and we were quite impressed! The principle of using a bell jar to protect the hard drive inside so the world can see it spinning is really a cool idea, but his execution of this project is excellent. It was reportedly so good that an unnamed college actually asked him to build one of his drive displays for them.

The Mark III is an excellent build, and the little hard drive has been swapped to the front of it for better visualisation. The disadvantage of the iPod Mini used for the Mark III build is that it actually buffers enough so that the read head doesn’t have to spin during the entire song.  Because of this, we thought that his first build, nicknamed [pink], was even more interesting, if ever so slightly less refined. By many of our hacking standards though, both are incredibly finished works of art!

Both these builds feature a plethora of LEDs to keep you entertained, and can be seen demonstrated after the break! [Read more…]

Quick and easy Arduino-powered theremin

[Martin] sent in a great guide to a simple Arduino based theremin. It’s a very small build – just a single common IC and some passive components – and easy enough to build in an afternoon.

The theremin is based on a simple LC oscillator built around a 7400 quad NAND gate IC, a wire antenna, and a few caps and resistors. When a hand moves closer to the antenna, the frequency of the oscillator increases; when a hand moves away, the frequency decreases. On the software side, the oscillator is connected to the internal hardware counter of the Arduino. Every time there’s a change in the voltage output by the oscillator (all the time, varying slightly with the distance from a hand to the antenna), the counter increases by one. This counter is tallied up over 1/10th of a second, and the distance from the instrumentalist to the theremin can be determined. From there, it’s just outputting a frequency to a speaker.

All the code, schematics, and board layouts are available on [Martin]’s guide, and most of our readers probably have the parts to build this lying around their workbench. You can check out a video of [Martin]’s theremin in action on his guide.