Hackaday Links: Sunday, May 26th, 2013

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The warmer months cometh and it’s time to think of this year’s Burning Man. [Matt's] already set himself up with a sound-reactive LED project he calls the Seed of Life.

Older readers, and those who really know their hobby electronic history, will know the name Heathkit. Many readers tipped us off about their triumphant return. We’re not sure what form this reincarnation will take, but you can help shape it by participating in the survey.

Dust off that MSP430 launchpad and turn it into a composite video Pong console.

Here’s a way to use your Android phone as a computer mouse.

We’re not quite sure what this is, but turn your volume down before watching the video about a modular sythesizer hack.

[Arkadiusz Spiewak] wrote in to share some of the printing success (translated) he’s had recently with the H-bot style printer we saw a while back.

Strap an Arduino and an Electric Imp to your arm (and everyone else’s) and it’ll remember everyone you meet. You know, kind of like Google Glass but with geeky arm-wear instead of geeky headgear?

And finally, [Nerick] has just finished a thermometer project using Nixie tubes (translated).

Crown earns you the title King of the Junkyard

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[Greg Shikhman] wanted to use the school tools one more time before graduation. After hitting up some local motorcycle shops around town for parts he fashioned this crown for himself.

He didn’t pay ‘the iron price‘ as the motorcycle roller chain is waste material anyway. Chains do wear out and these were left over after being replaced with new ones. He first cleaned them up with a bit of WD-40 solvent, xylene, and soapy water to cut through the grime. There was also a layer of black oxide which normally keeps them from rusting which he peeled off with a dunk in some hydrochloric acid.

Chains are flexible and this would have made for a disheveled looking crown. The fix involved using an aluminum form the size of his head to keep the crown in round while he did his TIG welding. A double row of polished steel ball bearings take the place of jewels. As if the ten-pounder wasn’t painful enough he added four rings of bicycle chain as accents which he admits makes the thing unwearable because they dig into his noggin. We still don’t think that’s a good enough excuse to post about the project and not include an image of him wearing the thing during the junkyard coronation.

It would be fun to see a follow-up king-ring with similar LED features as that engagement ring but using this heavy-metal design style.

Detecting galactic rotation with software defined radio

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Last summer in the heyday of software defined radio via USB TV tuners we asked hackaday readers a question: Is anyone using everyone’s favorite method of SDR for radio astronomy? It took nearly a year, but finally there’s an awesome project to turn a USB TV tuner into a radio telescope. It’s from the fruitful mind of [Marcus Leech] (PDF warning), and is good enough to detect the rotation of the galaxy with a three-foot satellite dish.

News of [Marcus]‘ work comes to us from [Carl] over at RTL-SDR.com who has been keeping tabs on the advances of building a radio telescope in a backyard. He’s been collecting a lot of interesting tidbits including this gif showing an arm of the galaxy entering and leaving [Marcus]‘ telescope’s field of view over the course of a few hours.

Not only can [Marcus]‘ telescope record continium measurements – basically, a single-pixel camera sensitive to only one frequency – it can also produce spectral plots of the sky. Combine the ability to measure multiple frequencies at the same time with the Doppler effect, and [Marcus] can measure the rotation of the galaxy with a USB TV tuner. That’s just awesome in our humble opinion.

If you already have an RTL-SDR TV tuner and a largish satellite dish, [Marcus]‘ project should be fairly inexpensive to replicate; the feed assembly is made out of a coffee can, the amplifiers are repurposed satellite television equipment, and all the software – [Marcus]‘ own simple_ra tool for GNU Radio – is open source. Of course with a 3 foot diameter dish, it will be impossible to replicate the data from huge radio telescopes. Still, it’s an impressive piece of work that leaves us searching craigslist for an old C-band dish.

Update: Live video played on LED strip display

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[Paul] took this LED display along with him to Maker Faire. To give it some interactivity he figured out a way to make it play live video. It is also activated using some stomp actuators built from piezo speaker elements and rubber floor mats.

This moves his original project in new directions. Back in February he was showing off the RGB LED strip display. He had it playing video but that was all dependent on using previously processed files. This upgrade uses a BeagleBone Black (the newest rendition of the ARM-based development board). [Paul] had tried using a Raspberry Pi board but had trouble with the webcam (mounted above the LED display) dropping frames. With the new board he is able to use the Video4Linux API to capture 30 frames per second and push them out to the display.

So far he’s had five out of the 1920 LEDs die on him. This shows off a couple of good things about using strips like this. A dead pixel doesn’t affect its neighbors. And replacement is as easy as cutting the ribbon on either side of the bad component, then soldering a new segment in place.

 

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