Ghost Guitar Plays Hendrix

Purple Haze all in my brain,
lately guitars they don’t seem the same,
[Josh] is playin’ funny but I don’t know why
‘scuse me while he electrifies.

[Josh] wanted to experiment with playing a guitar by different means. We’ve seen a few guitar hacks that use servos to play, and Arduino-based guitars that replace the strings with membrane potentiometers, but he decided to try a different approach. He’s using a permanent magnet and the electromagnetic effect to play the string.

Purple Haze all around,
all those amps are runnin’ up or down.
Are my strings all goin’ left or right?
Whatever it is, electromagnetism is pushin’ me outta sight.

To do this, he put a large permanent magnet next to the string and ran an alternating current through the string itself. When the current and the magnetic field interact, the string is pushed, like the bearing of a motor.  When the current goes the other way, the string is pushed in the opposite direction. Because he is using an alternating current (driven through a MOSFET tied into a frequency generator), he was able to control the frequency of this, and find the frequencies that made the string resonate, including the harmonics that give guitars their unique sound. It’s a pretty neat hack, but don’t forget that he is dealing with quite a lot of juice: if you were to inadvertantly touch the string and ground it to earth, there is enough current in the circuit to kill you.

Yeah, [Josh’s] hack is all about the right hand rule,
I know that he’s no hacking fool,
you’ve got my E string resonating, resonating so fine
just don’t touch it, or you’ll end your time
Help me, yeah, Purple Haze!

(with apologies to the ghost of [Jimi Hendrix], guitar hacker supreme)

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Make a Microphone Out of a Hard Drive

[Rulof Maker] has a penchant for making nifty projects out of old electronics. The one that has caught our eye is  a microphone made from parts of an old hard drive. The drive’s arm and magnet were set aside while  the aluminum base was diagonally cut into two pieces.  One piece was later used to reassemble the hard drive’s magnet and arm onto a wooden platform.

v2_micThe drive’s arm and voice coil actuator are the key parts of this project. It was modified with a metal extension so that a paper cone cut from an audio speaker could be attached, an idea used in microphone projects we’ve previously featured. Copper wire scavenged from the speaker was then soldered to voice coil on the arm as well as an audio jack. In the first version of the Hard Drive Microphone, the arm is held upright with a pair of springs and vibrates when the cone catches sound.

While the microphone worked, [Rulof] saw room for improvement. In the second version, he replaced the mechanical springs with magnets to keep the arm aloft. One pair was glued to the sides of the base, while another pair recovered from an old optical drive was affixed to the arm. He fabricated a larger paper cone and added a pop filter made out of pantyhose for good measure. The higher sound quality is definitely noticeable. If you are interested in more of [Rulof’s] projects, check out his YouTube channel.

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Forgotten Rock Band Drum Controller as a MIDI Instrument

Happen to have an old Rock Band drum controller collecting dust in your living room? If you also have a spare Arduino and don’t mind parting with that plastic college memento then you’ve got the bulk of what could potentially be your new percussive MIDI instrument. In his project video [Evan Kale] outlines the steps necessary to turn that unloved plastic into a capable instrument for recording.

The whole process as outlined by [Evan] in under seven minutes. This looks like a great weekend endeavor for those of us just starting out with MIDI. After cracking the back of the Guitar Hero drum kit controller open, the main board within is easily replaced with a standard sized Ardunio (which matches the present mounting holes exactly). About 4:50 into the video [Evan] explains how to add a basic perf-board shield over the Arduino which connects the piezo sensors in each of the drum pads to the analog pins of the micro-controller. The MIDI jack that comes built into the back of the kit can also be reused as MIDI out when wired to the Arduino’s serial out pin. By adjusting [Evan’s] example code you can dial in the instrument’s feedback to match the intensity of each hit.

The video with all of the details is after the jump. Or you can check out a MIDI hack that goes the other way and uses a drum kit as a Guitar Hero or Rock Band controller instead

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Hackaday Prize Entry: Orchestral Invention Defies Convention

Like many of us, [Laurens] likes video game music and bending hardware to his will. Armed with a Printrbot, a couple of floppy drives, and some old HDDs, he built the Unconventional Instrument Orchestra. This 2015 Hackaday Prize contender takes any MIDI file and plays it on stepper and solenoid-based hardware through a Java program.

A while back, [Laurens] won a Fubarino in our contest by using a MIDI keyboard and an Arduino to control the Minecraft environment with Legend of Zelda: Ocarina of Time songs. The Unconventional Instrument Orchestra uses that Fubarino of victory to control the steppers of two floppy drives. He only needed three pins to control the drives—one to enable, one to set the head’s direction, and one to make it step once per pulse.

If ever you’ve been around a 3D printer, you know they make music as a natural side effect. The problem is getting the printer to obey the rests in a piece of music. In order to do this, [Laurens] used his software to control the printer, essentially withholding the next command until the appropriate time in the song.

The percussive elements of this orchestra are provided by a hard drive beating its head against the wall. Since it’s basically impossible to get an HDD to do this as designed (thankfully), [Laurens] replaced the control board with a single transistor to drive the coil that moves the head.

[Laurens] has made several videos of the orchestra in concert, which are a joy all their own. Most of the visual real estate of each video is taken up with a real-time visualization of the music produced by the software. There’s still plenty of room to show the orchestra itself, song-specific gameplay, and a textual commentary crawl in 16-segment displays. Check out the playlist we’ve embedded after the break.

The 2015 Hackaday Prize is sponsored by:

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Combining Musical Hatred with Target Practice

Not everyone can agree on what good music is, but in some cases you’ll find that just about everyone can agree on what is awful. That’s what the people over at Neo-Pangea discovered when they were listening to Internet radio. When one of those terrible songs hits their collective eardrums, the group’s rage increases and they just need to skip the track.

This is how Engineers act if the song is super-awful
This is how Engineers act if the song is super-awful

Rather than use a web app or simple push button to do the trick, they turned the “skip” button into a NERF target. They call their creation the Boom Box Blaster and made a fantastic demo film video about it which is found after the break.

Inspired by a painting in the office, the target takes the form of a small hot air balloon. The target obviously needed some kind of sensor that can detect when it is hit by a NERF dart. The group tried several different sensor types, but eventually settled on a medium vibration sensor. This sensor is connected to an Arduino, which then communicates with a Raspberry Pi over a Serial connection. The Pi uses a Python script to monitor the Arduino’s vibration sensor. The system also includes some orange LEDs to simulate flames and a servo attached to the string which suspends the balloon from the ceiling. Whenever a hit is registered, the flames light up and the balloon raises into the air to indicate that the shot was on target.

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Vintage Vinyl Laser-Etched on a Tortilla

[UpgradeTech] had a proof-of-concept itch they needed to scratch: making a playable record out of a tortilla using a laser cutter. The idea was spawned from the goofy “tortilla vinyl” YouTube video.

Uncooked flour tortillas were used. Corn tortillas were too lumpy while cooked tortillas shredded on the record player. To get the recording onto the tortilla, Audacity was used to modify a stereo WAV file. Using the RIAA equalization standard is a great choice here as it was originally adopted to prevent excess wear and tear on record grooves as the needle passed through. A Python script generated the files for the laser cutter, creating a text file with the sound data which was then processed into a vector PDF of the grooves. For each record it takes 30 minutes for the laser cutter to turn a simple flour tortilla into the musical variety.

Each tortilla can play 30-40 seconds of music at 45 or 78 RPM, but they start to warp once they dry out. Time to build a humidor around the record player! There is background noise that can make certain songs harder to hear, but there is unarguably audible music. There is plenty of room for optimizing the sound file, grooves, and cutting. We hope this project inspires others to make their own musical tortilla. Playing with your food has taken on a whole new meaning!

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Hackaday Prize Entry: 3D Printed Modular Keyboard

There is a big community of people creating all kinds of synthesizers, but until now no one has attempted to make a keyboard controller like the one [Tim] created. Not only has he created the keyboard synthesizer, but he’s developed one that is modular and 3D printed so you can just expand on the synth you have rather than go out and buy or build a new one.

The design has a lot useful features. Since the design is modular, you can 3D print extra octaves of keys if you need, and simply build off of the existing keyboard. The interior has mounts that allow circuit boards to be screwed down, and the exterior has plenty of available places to put knobs or sliders. Anything that could possibly be built into a synthesizer is possible with this system, and if you decide you want to start small, that’s possible too!

All of the design files are available from Pinshape if you want to get started. The great thing about this controller is that you could use a 555-based synth in this keyboard controller, or a SID synth, or any other synth you could think of!

The 2015 Hackaday Prize is sponsored by: