A primer on dynamic loading

[Graphitemaster] is helping to demystifying the process of tailoring functions for dynamic loading. His tutorial shows how make a dynamic function that prints “Hello World” to the standard output. This is of course rudimentary, but if you have no prior experience with the topic you might be surprised at what actually goes into it.

Normally your compiled code has addresses in it that tell the processor where to go next. The point of dynamic loading is that the code can be put anywhere, and so static addresses simply will not work. The code above shows how a simple printf statement normally compiles. The callq line is a system call that needs to be replaced with something that will play nicely in the registers. [Graphitemaster] takes it slow in showing how to do this. Of course a dynamic function alone isn’t going to be much good. So the tutorial finishes by illustrating how to program a dynamic code loader.

Bring your LED matrix project into the living room

If you’re able to make a project look this good it shouldn’t be hard to convince that significant other to let you install it in a prominent place in the house. We think [Greg Friedland] pulled this off perfectly by building a 4′x8′ tablet controlled LED matrix.

First of all, everything looks better in a shiny case. It shouldn’t come as a surprise that this looks nice, thanks to the face plates which are mounted in a way that gives them a modern style (we’d expect to see this hanging in Ikea). They’re acrylic diffuser panels meant for used with lighting in a suspended ceiling. They do a nice job of scattering the light put off by the 544 LED modules that make up the display. The wiring was made easy by using LED strands where each pixel has its own control chip (WS2801). It sounds like the display will peak at around 160 Watts, which isn’t really that much considering the area. One nice touch that’s shown off in the video after the break is a full-feature iPad interface that even allows you to paint in light using your finger. But we’re also satisfied that [Greg] posted about the physical build too.

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Repairing a thermal imaging camera

[Mike] got his hands on this thermal imaging camera which is designed for use by Firefighters. As he’s demonstrating in the image above, it clips to a helmet and has a display what will let rescuers see through heavy smoke. But this one isn’t working right so he cracked it open and repaired the damaged board.

The hour-long video (embedded after the break) is quite interesting. He starts with a disassembly of the unit, before diving head-first into trouble shooting. There is a PCB inside that fills the entire U-shaped enclosure. The thermal sensor’s habit of cutting out seems to be a symptom of this design. There is one weak point where the board is very narrow. Flexing or vibrating that section will reset the sensor, and [Mike] ends up replacing a couple of components before the thing is fixed. These include a resistor and a ferrite bead both of which are suspected of having cracks due to that board flexing. The rest of the video is spent with an EEVblog-style look that the components and the construction.

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Are you smarter than a raccoon?

[Ben] has a raccoon problem. It seems that it’s not uncommon for him to come face-to-face with a pesky raccoon in the middle of the night, in his living room. We think most people would solve the problem by preventing the raccoon from entering the home. But [Ben] just seems hell-bent on catching him. Most recently he’s added motion-sensing to a live trap which he installed…. in his living room.

So [Ben] has cat’s which that to roam at night. They have free range thanks to a cat door which the hungry pest has been exploiting. Apparently the masked robber has a taste for cat food and that’s what keeps him coming back. [Ben] has been using the cat dish as bait but up to this point the live trap hasn’t worked. You see the raccoon isn’t going inside to get the food, but reaches through the cage and pulls pieces out one at a time. The solution is to put up a solid surface around the cage, and hope that the motion sensor will get him this time. Although we’ve linked the most recent post above, you’ll want to page through his blog for the whole story.

Wouldn’t it be better to install some kind of automatic lock that only lets in the kitty?

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Stair tricking skateboard

This skateboard concept lets you travel down stairs almost as smoothly as gliding down a hill. This seems to be the eighth iteration in [PoChih Lai's] attempts to add functionality to a board which will make it the ultimate ride for an urban outing. Check out the video after the break to see just how well he did.

We’ve seen hand carts that use six wheels to make stairs a breeze using a triad of wheels as a single-wheel replacement. This was actually the main concept early on in the design. But the drawback to this method is that the design takes up a lot of room and [PoChih] also made the deck much bulkier to keep you from getting a foot caught in the mechanism. The final design does away with the end-over-end concept and adopts a rocking mechanism. The board hangs from a bar which serves as the pivot between the two wheels. This way the wheels can absorb the brunt of the motions, and the base of the deck can slide across the fronts of the steps if needs be.

We were talking about this here at the Hackaday office and the point was made that this is like YT’s skateboard from Neal Stephenson’s Snow Crash. Did you hear that it’s headed to a theater near you?

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Heading to MakerFaire Kansas City

Today, I’m heading out to Makerfaire Kansas City. I plan on covering this event quite extensively. If you see me, don’t hesitate to come up and introduce yourself. I may even have a custom cut vinyl hackaday sticker left for you. Since we are Hackaday, I plan on trying to get into the details and get interviews following [Ian Lesnet's] lead. We don’t just want to see a neat thing on a table, we want to know how it works and what roadblocks that person ran into. See you there!


Hackaday Links: June 22, 2012

For when you want something huge machined

Turn your volume down for this video. It’s the HSM-Modal CNC mill carving a full-sized car out of styrofoam, applying clay to the foam core, and machining the clay at 50 meters per minute. Yes, we’ve seen this machine before, but never in action. It only took a little over 24 hours to make this full-size model car.

Microscope into a drill press

If you need to drill some PCBs, [wotboa] has a neat build for you. He built a micro drill press out of a microscope. It’s a damn good idea if you can find a quality microscope base; those things usually have exceptionally high precision. The ‘hack’ part is a $7 Harbor Freight rotary tool, some PVC pipe, and a PWM control for the motor – home-made, natch.

I’m telling you, they need to get [River] out of the library. Work on it [Moffat].

[Alan] made a TARDIS book case, and he decided to share the plans with us. Just the build to combat the severe lack of woodworking and Whovian stuff on Hackaday. Vashta Nerada hopefully not included.

Money can’t buy happiness, but you sure can sell it

[Greg] sent in some info on Disney’s ‘glow with the show’ hats they sell at the California Adventure park. For $25, you get a hat with RGB LEDs in the mouse ears that synchronize with the World of Color show every night. There’s a better description of the hats here, but we’re thinking these are very similar to the Coldplay Xylobands we saw at this year’s Grammys. Anyone want to tear some mouse ears apart?

An exceptionally low-tech radio telescope

[Impulse405] found a poor man’s radio telescope on Instructables and decided to share it with us. [Z0rb] found a 10-foot dish in the garbage and quickly absconded with this retro hardware. After adding a power supply and a meter-based total power receiver, [Z0rb] had a radio telescope that covered wavelengths from 850 to 2200 MHz.