Precision CNC Drawing with EtchABot

Turning the classic toy Etch-A-Sketch into a CNC drawing tablet intrigues a large number of hackers. This version by [GeekMom] certainly takes the award for precision and utility. Once you build something like this, you can hardly stop writing firmware for it; [GeekMom] produced an entire Arduino library of code to allow joystick doodling, drawing web images, and a self-erasing spirograph mode. The topper is the version that runs as a clock!

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The major hassle with making a CNC version of this toy is the slop in the drawing mechanism. There is a large amount of backlash when you reverse the drawing direction. If that isn’t bad enough, the backlash is different in the vertical or horizontal directions. Part of [GeekMom’s] presentation is on how to measure and correct for this backlash.

The EtchABot uses three small stepper motors. Two drive the drawing controls and the third flips the device forward to erase the previous drawing. The motors are each controlled by a ULN2003 stepper motor drivers. An Arduino Uno provides the intelligence. Optional components are a DS3231 Real Time Clock and a dual axis X-Y joystick for the clock and doodling capability. Laser cut wood creates a base for holding the Etch-A-Sketch and the electronics.

The write up and details for this project are impressive. Be sure to check out the other entries in [GeekMom’s] blog. Watch the complete spirograph video after the break.

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Emulating and Cloning Smart Cards

A few years ago, we saw a project from a few researchers in Germany who built a device to clone contactless smart cards. These contactless smart cards can be found in everything from subway cards to passports, and a tool to investigate and emulate these cards has exceptionally interesting implications. [David] and [Tino], the researchers behind the first iteration of this hardware have been working on an improved version for a few years, and they’re finally ready to release it. They’re behind a Kickstarter campaign for the ChameleonMini, a device for NFC security analysis that can also clone and emulate contactless cards.

While the original Chameleon smart card emulator could handle many of the contactless smart cards you could throw at it, there at a lot of different contactless protocols. The new card can emulate just about every contactless card that operates on 13.56 MHz.

The board itself is mostly a PCB antenna, with the electronics based on an ATXMega128A4U microcontroller. This micro has AES and DES encryption engines, meaning if your contactless card has encryption and you have the cryptographic key, you can emulate that card with this device. They’re also making a more expensive version that also has a built-in reader that makes the ChameleonMini a one-stop card cloning tool.