Hackaday Links: November 28, 2010

November 28, 2010 by Mike Szczys 6 Comments

The Clock Clock

This digital display is made from several analog clocks with thick hands. Together they make something of a 7-segment display, which can be used to display the time. It reminds us of the “Shared Time” installation we covered previously. [Thanks Drum365 via Anonimiss Files]

Quickly desolder lots of parts

[Rhys Goodwin] is grabbing parts from junk PCBs but he’s not using a rework station. Instead it’s a hot-air gun and a brisk tap on the bench to send the parts flying. Well, at least he’s not using a blow-torch like [Ben Heck] does.

Binary Hero

This bank of 8 toggle switches is the controller for Binary Hero, a geeky take on Guitar Hero. When you see a decimal number come down the screen set your toggle to the binary equivalent in time or the game will be over before you know it. [Thanks Fabien]

Quick fan POV

[GMG] took a small persistence of vision board and slapped onto an oscillating fan blade. Along with a couple of magnets on the safety cage this display is a persistence of vision hack you can pull off in an hour or two.

Speed up laser etching

[James] figured out a way to cut down on the time it takes to etch multiple copies of one item with a laser cutter. It doesn’t run the laser faster, but orients the pieces in a way that means less movement of the head while the laser is not on. Read through his article and see if this method can help you out when doing some CNC work.

Epic Wooden Marble Run For Kids’ Room

November 27, 2010 by Mike Szczys 30 Comments

Some parents buy kinetic sculptures for their kids at art or craft fairs. Not [Steve Moseley], he turned his kids’ hovel into a sculpture by wrapping a marble run around the entire room. It’s big enough, with so many features that finding a banner image was a bit tough. After the break we’ve embedded a video where you’ll see a wagon wheel lifter, plenty of gravity-fed curves, loops, inclines, rockers, a stair-step lifter, and… well you get the idea.

Considering the scope of the project it was remarkably inexpensive; about $70 in wood, $40 for the glass marbles, and around $60 for everything else. We’re glad he shared his building methods with such verbosity. You’ll need a well-stocked shop. Fine work like this requires tools common for woodworkers, but we’d bet the band saw and oscillating spindle sander were a godsend.

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Balancing Inverted Pendulums

November 27, 2010 by Mike Szczys 38 Comments

The robot above can balance an inverted pendulum. But wait, it gets better. It can balance an inverted pendulum that is articulated in the middle like the one seen above. Wait, wait, wait… it gets even better. It can start with the pendulum hanging below the sliding carriage, flick back and forth to get the two segments swinging, and then come to equilibrium with the pendulum as seen above. Once there, it can recover from a bit of a shove, like some of the big boys. Very impressive, even when compared to two-wheeled balancers. See for yourself after the break.

We don’t have very much information on how this works. We do know that it was a seminar paper from a student at the University of Stuttgart but the rest is pretty much a mystery. Does it use visual processing? What kind of controller is driving this thing? We want to know the details but haven’t yet found a copy of the paper. If you know where we can get our mitts on it please leave a comment below.

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Barcode Challenge For Radio Operators

November 27, 2010 by Mike Szczys 32 Comments

[Scott Harden] came across a few posts about QR code matrix barcodes coming through on the 40m baud radio band. A few operators had captured the signals and assembled them into the code block seen above but they weren’t able to get a clear enough shot for a smartphone to decode the image. [Scott] took on the challenge and decoded the mysterious message himself. He tried some graphic editing to separate and enhance the color channels in order to up the contrasts of the image. This helped, but still couldn’t be read automatically. In a move similar to those seen in Hackaday’s own barcode challenges he dropped the image into Inkscape so that he could manually clean it up. Once it was overlaid on a grid the job was pretty simple. the left side did require some more image manipulation and precision”squinting” to eliminate interference from the vertical banding, but he managed to get the message. We won’t spoil it here in case you want to take on the challenge yourself. Good luck!

Automated Chicken Coop Door Is Solar-powered

November 27, 2010 by Mike Szczys 12 Comments

[Fileark] has been busy with the hacks lately. This time around he’s built a solar-powered chicken coop door that opens in the morning, and closes at night. A single motor slides the door open and closed using a loop of spring-loaded string. There are limiting switches on either side of the door jamb to ensure proper positioning. The grey box seen above houses the hardware; a regulator for the solar panels perched atop the roof line, a battery from a broken UPS, and the driver board itself. An AVR chip running the Arduino bootloader monitors a phototransistor to detect sunup and sundown, driving the door motor appropriately using a pair of relays.

Check out the demonstration and hardware overview after the break. [Fileark] was inspired to build his after seeing the alarm-clock coop door. We don’t know if he got a chance to look at the vertical coop door, but we think his less mechanically-complicated solution is just as elegant.

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Surprisingly Simple Magnetic Card Spoofer

November 27, 2010 by Mike Szczys 5 Comments

[Craig’s] magnetic card spoofer is both simple and brilliant. There are two parts to spoofing these cards and he took care of both of them. The first part is getting the actual card data. He designed the spoofer board with a header that connects to a card reader for doing this. The second part is the spoofing itself, which is done with an electromagnet. As with past spoofers, he wrapped a shim with enamel-coated magnet wire. An old knife blade was picked for its thickness and ferromagnetism. This magnet is driven by an ATtiny2313 which stores the data, and is protected by a transistor driving the coil. There were a few design flaws in his board, but [Craig] was able to get the same track data out of the spoof as the original card despite the LED being used as a protection diode and an ‘aftermarket’ resistor on the transistor base.

Arduino Electronic Speed Control Explained

November 26, 2010 by Mike Szczys 29 Comments

You can salvage some nice motors out of optical drives but they can be tricky to control. That’s because brushless DC motors require carefully timed signals used in a process called Electronic Speed Control (ESC). [Fileark] built and ESC using an Arduino and has a couple of posts explaining the concept and demonstrating how it works. His test circuit uses six 2N2222 transistors to protect the Arduino from excessive current. You can see six red LEDs above which are inline with the base of teach transistor. This gives visual feedback when a transistor is switched, a big help for troubleshooting your circuit.

Once you’ve seen the videos after the break you’ll probably come to the conclusion that this is an impractical way to use a brushless motor. But it is a wonderful way to learn about, and experiment with the concept of ESC. Chances are you can get your hands on an old optical drive for free, making this an inexpensive weekend project.

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