While working on his masters degree in controls and robotics, Hack-A-Day reader [Kenn Sebesta] developed a cheap method for digitally reading analog gauges. This method was necessitated by needing to take over 3000 measurements using a dial indicator during his thesis work. The system is implemented in Matlab and uses a webcam to take a picture of the gauge. Once picture is taken it goes through several steps: First, it is reduced to a single color. Then, edge extraction is used to find the lines. Next, the lines are thickened. Finally, the Hough transform is applied to find the longest line: the needle. All that is left to do is measure the arc back to the zero point and match it to your scale. Using this method Kenn’s laptop can take 4 measurements per second.

Continue reading “Digitally Reading Analog Gauges” →

The RepRap project hopes to build a universal constructor; a machine that can replicate itself and make a number of useful products. The machine is open source and uses fused deposition modeling (FDM) to layer melted material into parts. One of the key technologies in self-replication is the ability to lay conductive circuit paths. The RepRap machine is able to lay down conductive material and an insulator. For a conductor they are using Wood’s metal, a fusible alloy that has a melting point of 158degF. To demonstrate this conductor laying ability they built the FDM head pictured in a commercial FDM machine. The project makes some reasonable compromises; it doesn’t attempt to make common items like brass bushings, microcontrollers, stepper motors, self-tapping screws, and power supplies.

I had seen the link for Jonathan Westhues’s original proximity card spoofer floating around recently and decided to check out the site to see if anything had changed since we originally covered the story. Well, he’s got a brand new version. This one has far more features than the original, mostly because of the extra processing power provided by an Atmel AT91. The new spoofer can handle multiple modulation schemes; which means it is capable of copying almost any 125kHz or 13.56GHz ID-only card. Although it can’t clone cryptographic cards, it does have a full feature set for communicating with them. By connecting the USB port to a computer you can see an “oscilloscope view” of the signal from the card to assist in writing demodulation code. If you are serious about doing RFID research this hardware is a must-have. You could buy a standard reader, but that would tell you nothing about the protocol. This is definitely a clever tool and certainly impressive for something smaller than a business card.

UPDATE: Jonathan Westhue’s work was mentioned in a CNN story Feb 14th. You can watch the video here. [thanks David]

Continue reading “Proximity Card Spoofer: Proxmarkii” →

Here are some really thorough instructions for building geodesic domes. This particular set of plans was developed by some Burning Man attendees who wanted a comfortable structure that would stand up to the elements. The dome is made of 30 triangles cut from double layered cardboard, 5 wood triangles with vents, 5 wooden doorway triangles, and 5 cardboard doors. The majority of the triangles are bolted together to form pentagons that are then bolted to each other. With all of the triangles painted and seams sealed with duct tape the structure is water proof. All of the dimensions and assembly instructions are provided to create a dome 12’7″ in diameter and 6’3″ in the center.

[thanks l0cke]

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Sometimes the two-dimensional layout of a circuit board doesn’t tell the whole story so Matthias Wei?r created Eagle3D. Once the board is laid out in EAGLE you export it using the Eagle3D tool. The tool has predefined parts that it then uses to render the board in 3D using POV-Ray, a free ray-tracing program. There are a lot of parts included already, but you can define more using POV-Ray’s Scene Description Language. Using POV-Ray you can also make 3D movies your board

Reader [Franz Gabel] purchased a POV kit from ladyada and started modifying it for his own application. He assembled the POV without a PCB so it could fit inside a small metal pipe and attached a leather lanyard. He’s still in the early stages of the project. It is fully assembled, but he’s working on additions like a docking station to recharge and download new messages. He’s also developed a Flash based system for generating new .c files based on text input. Here is his forum post about his project (Coral CDN, so ladyada doesn’t break my arm).

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You could spend hours exploring the R/C Tank Combat website, so we will highlight one project to get you started. Steve Tyng built this awesome model based on the Russian T34-85 tank. The body is all wood an uses stainless steel axles salvaged from a printer. The original drive system used 24-volt DC motors from dot-matrix printers, but they’ve since been replaced. The most tedious part of this build appears to be the tracks which are made from a treadmill belt sandwiched between wooden blocks. The turret rotates and the barrel can elevate as well. The entire turret package can be easily removed. Inside is a cheap paintball gun that has been lightened and has a small RC servo bolted on to depress the trigger. Definitely have a look at the Maryland Attack Group’s other projects like their field artillery and armoured cars.

[thanks Jason]

Continue reading “RC Paintball Tank Built From Printer Parts” →