Mini IR theremin

[Chris] at PyroElectro sent in a great 8-part write-up of a miniature infrared theremin.

The theremin is based on a PIC microcontroller and an infrared distance sensor.  The build log goes through the theory of operations for the IR sensor and tone generation. [Chris] definitely does a great job showing the math that went into the design.

Although this project isn’t a true theremin because it operates on light like a few other projects we’ve covered in the past, it’s easier to play because of the hard-coded notes. The build does show some promise though – he could likely expand it to use more accurate ultrasonic sensors or use, “two proximity sensors, one for treble and one for bass like an accordion.”

The theremin is usually played with both hands providing a continuous pitch and volume. This project features hard-coded, discrete notes, so we’re wondering about the possibility of implementing MIDI on this IR theremin. The original MIDIbox was based on the same microcontroller as this project, so it’s definitely a possibility.

Check out the video of the theremin in action below.

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Reverse engineering VxWorks (which replaces Linux on newer routers)

The Linksys router seen about is a WRT54G version 1. It famously runs Linux and was the source of much hacking back in the heyday, leading to popular alternative firmware packages such as DD-WRT and Tomato. But the company went away from a Linux-based firmware starting with version 8 of the hardware. Now they are using a proprietary Real Time Operating System called VxWorks.

[Craig] recently put together a reverse engineering guide for WRT54Gv8 and newer routers. His approach is purely firmware based since he doesn’t actually own a router that runs VxWorks. A bit of poking around in the hex dump lets him identify different parts of the files, leading to an ELF header that really starts to unlock the secrets within. From there he carries out a rather lengthy process of accurately disassembling the code into something that makes sense. The tool of choice used for this is IDA Pro diassembler and debugger. We weren’t previously familiar with it, but having seen what it can do we’re quite impressed.

[Image via Wikimedia Commons]

VU meter scarf lights up the night

vu_meter_scarf

[Eli Skipp] wrote in to share a project she has been working on bit by bit, for over a year – an LED VU meter scarf. The project was originally going to be built using a custom PCB, but no matter how long she spent troubleshooting the piece, it just wouldn’t work right. She eventually broke down and purchased a VU meter kit, which worked out quite a bit better than the homebrew version.

The VU meter circuitry is tucked away inside the scarf as she shows in the video below. The LEDs are connected using conductive thread sourced from Lamé Lifesaver, which she says is far more durable than other threads she has tried. After originally testing the VU meter, she was unimpressed by the output of the LEDs, so she swapped them out for brighter ones, which look much better. It looks like it works quite well – we definitely dig the idea of a scarf with a built-in VU meter, even if it was partially built from a kit.

Continue reading to see [Eli] give a quick demonstration and a rundown of the scarf’s construction.

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Humanoid robot listens to music, plays along on his Theremin

robot_playing_theremin

Researcher and YouTube user [mspetitegeek] along with her lab mate [Tatsuhiko Itohara] have been fortunate enough to spend some time working with the HRP-2 humanoid robot from Kawada Industries. Their research has seemingly been focused on using the robot to create real-time interactions with humans for entertainment purposes, at the very least.

The program they created allows the HRP-2 to listen and watch its human counterpart while he plays the guitar in order to recognize a beat pattern. Once the robot catches on, it plays along on his Theremin, matching both notes and rhythm perfectly. Since the human operator is clearly playing at a fairly relaxed pace, we are curious to see a demonstration where the robot required to match a snappier tune – it could be quite interesting.

In the meantime, we’re content to just sit back and enjoy the Mogwai-esque tones of the HRP-2 rocking the Theremin.

Keep reading to see a short video of the HRP-2 in action.

[Read more...]

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