Hacking cakes with LEDs, the sequel!

A few weeks back we ran a piece about the convergence of making and baking in an attempt to create a cake festooned with working LEDs. The moral was that not every creative idea ends in victory, but we applauded the spirit it takes to post one’s goofs for the whole internet to see and to learn from.

[Craig]’s LED matrix proved unreliable…and the underlying cake didn’t fare much better, resembling that charred lump in the toaster oven in Time Bandits. The cakes-with-lights meme might have died right there if not for a fluke of association…

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How Canonical automates Linux package compilation

pandaboard

What do you do when it’s time to port the most popular Linux distribution to a completely different architecture? Canonical employee [David Mandalla] works on their ARM development team and recently shared the answer to that question with his fellow Dallas Makerspace members.

Canonical needed a way to compile about 20,000+ packages for the ARM platform, however they did not want to cross-compile, which is quite time consuming. Instead, they opted to build a native solution that could handle the load while ensuring that all packages were compiled securely. To tackle this immense task, [David] and his team constructed a 4U server that runs 20 fully-independent ARM development platforms simultaneously.

The server is composed of 21 PandaBoards, small OMAP development boards featuring a dual-core ARM cortex processor with just about all the connectivity options you could possibly ask for. One board operates as the server head, keeping track of the other 20 modules. When someone requests server time to build a package, the main board checks for unused server, triggering a relay to reboot it before the server is automatically reimaged. Once the pristine, secure environment is ready to go, it’s handed off to the customer who requested it.

If you’re interested in learning more about the build process, [David] has put together a blog with additional details.

[Thanks Leland]

Crosshair aiming system for your laser cutter

diy_laser_crosshairs

[Rich] was having quite a bit of fun with his newly-acquired laser cutter, but was not impressed by the stock aiming laser that came with it. The problem with the built-in laser is that it did not actually follow the cutting laser’s path – instead, it has to be calibrated for a fixed focal length. This becomes problematic when engraving and cutting since they require different focal lengths, so it becomes a guessing game as to where the cutting laser will actually end up in respect to the aiming laser.

An additional optic module that solves this problem can be had for about $300, but after sinking $2500 into the laser setup, [Rich] was not inclined to purchase one. Instead, he bought a pair of cheap laser levels online and scavenged the line lens from one module, which was mounted on the laser cutter’s existing aiming laser. The second module was epoxied to the top of the cutting head, to create a set of cross hairs on the work surface.

As you can see in the video below, the hack works quite well, and the lasers are accurate at a variety of different focal lengths.

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Rescuing surplus blinkenlights

Because surplus LED panels from an early 1990s supercomputer is a completely reasonable thing to own, [William Dillon] set to work displaying them on his wall.

The LED panels came from a surplus CM-5 Connection Machine, best known from it’s role as the mainframe in Jurassic Park (only an empty case with LED panels were used in the movie). When not on Isla Nublar, the Connection Machine was a fabulous piece of engineering from the 1980s Artificial Intelligence revival. With some machines having 65,536 processors, it was used for AI research using Lisp (although we were never very good at Lisp.

[William] built a wooden frame out of 1×2 inch maple and installed an X10 module behind the panels as a remote switch. The panels themselves aren’t controlled by a computer, so the only thing left to do was to mount the power supplies. It’s impressive to see the massively over-engineered power supplies that were designed to source 5V @ 30A when the panels only draw 7 Amps. [William] says it was a design feature of the Connection Machine to spare no expense.

[William]‘s next plan is to reverse engineer the panels to display custom messages, and we can’t wait to see what he comes up with. We can’t explain why, but we really want to build one of these panels. Check out the pictures of [William] decommissioning the CM-5.

A suitcase for all your wardriving needs

[Corrosion] sent in a tip about the Weaponised Auditing Response System he built inside a suitcase that, “has all the tools (and then some) for a wireless assault”.

The WARS is equipped with two WiFi adapters and two bluetooth adapters for all the wardriving and bluejacking anyone could ever want. [Corrosion] also included a 4 channel, 2.4GHz video scanner for warviewing. Everything runs off of a 12 inch netbook that will eventually run linux, and we’re really liking the 1970s suitcase aesthetic the WARS has – it looks like [Corrosion] is about to step into the set of a Beastie Boys video.

We were wondering about including a long range RFID sniffing antenna (PDF warning) behind the monitor of the suitcase’s monitor and asked [Corrosion] about it. He said it sounded doable, but is out of funds at the moment, so if you know how to build a cheap RFID antenna with a 50 foot range, drop [Corrosion] a line.

There’s a video demo with some stills of the build included after the break.

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Fixing motorized window shutter battery problems

rolling_shutter_battery_fix

Living in a brushfire-prone area, [Erich] had a set of roller shutters installed to protect his home. Mains power can be spotty in emergencies, so the shutters are powered by NiMH batteries which are housed inside the shutters’ remote control units. After encountering a good handful of dead batteries, he decided it was time to search around for a better means of powering the shutters rather than pay another $80 AUD for batteries that he knew would fail in short order.

After disassembling the shutters and the remotes, he found a litany of problems. The remotes are ATMega-based, so he assumed the programming was robust, but he found that the charging algorithm was quite poorly implemented. The batteries were allowed to get extremely hot while charging, a result of the fact that charging was done for a set period of time rather than monitoring battery voltage. Additionally, the shutter motors required a 4 amp instantaneous current when activated, something that seemed to contribute to the quick draining of the 1500 mAH battery packs.

To remedy his issues, he upgraded to a much larger sealed lead acid battery pack, which he mounted in a wall cavity. The remotes were tweaked to add a modular power plug, enabling him to easily connect and disconnect the remotes as needed. Not only did he save a ton of money on constantly replacing batteries, he’s got a nice 12v power supply in the wall that he can tap into at will.