Building LED Walls On The Cheap

Around this time last year, [KopfKopfKopfAffe] was enlisted as a set designer and was told to build some sort of light effects for electronic music parties. The budget for the project wasn’t much at 200 Euros, but he did manage to build decent 5×5 RGB LED matrix that is fully controllable by a computer.

[KopfKopfKopfAffe] didn’t have the time or money to wait for manufactured PCBs, so a bunch of perfboard was placed in a CNC mill with a pen to act as a plotter. All the lines that needed soldered were drawn on by the mill, a feat that probably saved hours of looking at the design before committing solder to iron.

A total of five boards were constructed, each one capable of controlling five RGB LEDs. Each board can be dasiy-chained with an RS-232 serial connection for further expansion. The only thing that’s needed to control the matrix is 17 bits that includes an address and RGB color data for each LED. The system only cost about 10 Euros per node, but we think that could be significantly reduced by leaving out the Molex and DB-9 connectors. [Kopf] project turned out very nice, check it out after the break.

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Play Hide-and-go-seek With Infrared LEDs

Although we’re sure they exist, we wouldn’t want to meet anybody that can’t look back fondly on the halcyon days of youth that included playing hide-and-go-seek. Some kids never grow up and continue the tradition with geocaching or orienteering, but that sense of limitless discovery wanes over time. [Kurt] came up with a small scavenger hunt beacon that brings back the unending wonder that accompanies the unknown.

The beacon is just a simple ATtiny13 that flashes a message with an invisible IR LED. To receive the messages, [Kurt] made a scavenger decoder shield for an Arduino. The decoder includes a phototransistor and a 20×4 LCD display. All [Kurt] needs to do is hold the decoder up to the beacon for the text in the firmware of the ATtiny to be displayed. The beacon is only one inch square and powered by a watch battery, so it can be hidden anywhere.

[Kurt] suggests that the text of one beacon should provide the clue to the next. We’re thinking this is just a great excuse for a walk in the park. You can check out [Kurt]’s IR decoder getting data from a beacon after the break.

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Replacing A Phantom Limb With A Kinect

Nearly everyone has heard of phantom limb syndrome. It occurs sometimes after a limb is amputated, but the mind of the patient still thinks that the limb is attached. Generally regarded as a mix-up in the wiring of the damaged nerves, a phantom limb can be very painful. [Ben] has been working on a way to alleviate some of the pain and frustration associated with a phantom limb and fortunately for us he went for a Kinect, VR goggles, and gyroscope build.

Today, most therapies for phantom limb syndrome use a Ramachandran Mirror Box. The theory behind the mirror box is pretty simple – if someone recently lost a hand, just insert one hand in one side of the box and the arm stump on the other side. Looking into the box from the side with the good hand will trick the patient’s brain into thinking the amputated hand is still there. It’s a good therapy that has been very successful, but [Ben] thought he could do something that is a little more immersive.

[Ben]’s project uses a Kinect and VR goggles to put the patient in a virtual environment. With the help of a few gyroscopes, the patient gets a virtual representation of their whole self projected into their goggles. The technique isn’t terribly different from VR phobia treatment, although there’s much more electronics and math involved in [Ben]’s build. The first test subject said his pain was going down, so it looks like he might have a success on his hand (no pun intended).

Check out the demos of [Ben]’s treatment plan after the break.

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Electronic Candle Protects Sleeping Infant

[William] developed this temperature candle as a tool to help keep babies safe as they sleep. It seems that ambient temperature has an effect on Sudden Infant Death Syndrome (SIDS). This device is meant to alert you when room temperature is outside of the recommended envelope.

The board hosts an eight-pin PIC microcontroller (12F683P), a temperature sensor, RGB LED, and a push button. The round PCB is the same size as a votive candle, which is nice except that you’re going to have to drill a hole in your candle holder to accommodate that barrel jack.

The temperature sensor is read by the microcontroller and used to determine the color of the LED. Red is hot, blue is cold, and just right is somewhere in between. But if you’d rather know the exact current temperature you can press the button and it’ll blink out the Celsius reading using blue for 10 degree increments (three blinks is 30 degrees, etc.) and red for single degrees. Don’t miss the demo of the candle in the video after the break.

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Speedier Hard Disk Option For Your Mac Mini

[Andrew] was left wanting by the slow hard drive in his 2011 Mac Mini. He set out to add a 10,000 RPM drive and we think he did a great job of pulling it off. Luckily he also took the time to document the process so you can try it yourself.

As with a lot of Apple products, a big part of this hack is just getting the darn thing apart without breaking something. Once that’s done, you’re got to do a little bit of interface hacking. To save space Apple uses a non-standard SATA breakout cable so [Andrew] starts by ordering a second hard drive cable from the company. He then soldered a thin wire connecting 12V from the motherboard to the 12V pin on a SATA connector. From there it’s just a matter of altering the original hard drive sled to make room for the 500 GB WD Velociraptor drive. It fits below the original and serves as additional space instead of as a replacement.

Robotic Etch-a-Sketch Draws Grayscale Images

[Patrick] decided to make a computer controlled etch-a-sketch. While the idea is not that new, there is always a different way to accomplish a goal. An Arduino is used to control a pair of stepper motors which were sourced for pretty cheap, and even came with their own driver. Next a stand was mocked up using foam board, which helps determine where all the parts should live.

Next was a way to attach the steppers to the knobs, gears would be used and a collet meant for model airplanes was sourced to make the mechanical connection between gear and shaft. With everything set in place via foam board and paper printouts, it is off to get some thin plywood. The plywood is sent though a laser cutter creating most of the stand and gears. Now its all software, a program was whipped up for OSX which converts low res pictures into squiggly lines perfect for the etch-a-sketch to draw on its screen.

The results are quite impressive, join us after the break for a quick video.

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DIY Windows 8 Tablet

[hackitbuildit], from instructables, has brought us a a DIY windows 8 tablet. To make the tablet, an old laptop is used that meets the minimum requirements of windows 8 preview, a touch screen conversion kit, and of course the software itself. The laptop is first prepared by removing the casing around the screen, and if you just go by the pictures it kind of looks like he is ripping it apart! Though if you look at the video screws are being removed.

The screen is flipped around and laid on the keyboard with a couple spacers between them, as many laptops use the keyboard area as heat sinking. The touch screen is installed, and some wood strips are hot-glued to the outside to fill in the gap between the screen and base. With a little paint you’re left with a large, but functional windows 8 tablet to get started developing for.