Google Authenticator is an app that generates one time passwords (OTPs). These passwords are often used as a second factor of authentication, along with your normal password. OTPs work by having a shared secret and a synchronized clock on two devices. When you generate the password, a hash based on the secret and timestamp is created. This proves that you have access to the secret, and can only be used once.
To secure his Lego mini-figures, [Luca] built an authentication system using Google Authenticator and Arduino. A web app is used to generate a secret that can be configured into the Arduino using an array, and into Google Authenticator using a QR code. The Arduino is using a library that implements Time-based One Time Password authentication (TOTP).
There are some challenges, including keeping a good clock source on the Arduino, but this look like an interesting way to do authentication. After the break, watch a quick video overview of the project (for English captions, hit the CC button).
Continue reading “Using Google Authenticator with an Arduino”
Consider a book sitting on a shelf. You can lend it out to a friend, you don’t need a special device to read it, and if you are so inclined, you can photocopy it. This isn’t true with Kindle eBooks that place severe restrictions on what you can do with a book via DRM. Although it is possible to strip eBook DRM with a few programs on your computer, [Peter] came up with a fool-proof way that’s an amateur engineering marvel. He’s turning Kindle eBooks into plain text using Lego.
[Peter] is using a few bits of a Lego NTX system to press the, ‘next page’ button on his Kindle, then smash the space bar on his Mac to take a picture. These pictures are then sent to a cloud-based text recognition service. After a few hours of listening to plastic gears grinding, [Peter] has a copy of his eBook in plain text format sitting in his computer.
As impractical as it looks, using a robot, camera, and OCR is actually a really, really good way to turn eBooks plagued with DRM into a text file. Even if Amazon updates their DRM to make the current software cracking methods break, [Peter] will always have his Lego robot ready to scan a few hundred pages of text at a time.
Continue reading “Stripping Kindle DRM with Lego”
This rover built by [Sath02] is a great example that you don’t have to be a mechanical engineering wizard to get into robotics. He used LEGO pieces to help ease the difficulty of getting a rover up and running.
In this case the use of LEGO is strictly structural. The electronics are not the NXT parts you would expect to see when working with these popular toy blocks. Instead he’s put the Arduino Palm Plus into service. It’s an Arduino board that has rows of holes at either end to make it LEGO compatible. It also carries an LM293D motor controller and [Sath02] added an XBee module for wireless control.
At the top of the assembly is an IR distance sensor which is used for obstacle avoidance. You may not be interested in building and exact replica, but the techniques he uses for attaching the distance sensor, CD wheels, and fabricating the rest of the rover are good examples if you take on a LEGO build in the future.
Continue reading “Obstacle avoiding LEGO rover uses CDs for wheels”
LEGO parts are plastic. 3D printers make parts out of plastic. So the transitive property tells us that a LEGO 3D printer should be able to recreate itself. This one’s not quite there yet, mostly because it doesn’t use plastic filament as a printing medium. Look close and you’ll probably recognize that extruder as the tip of a hot glue gun. If all else fails you can use the machine as a precision hot glue applicator.
The instructions to make your own version include the design reference and a few ideas for getting the most out of the glue dispenser. For the design phase [Matstermind] used LEGO Digital Designer. It’s basically CAD with the entire library of LEGO parts available as building blocks. from there he assembled the machine which is controlled by an NXT brick. He goes on to link to a few different printing mediums. There’s instructions for using crayons to make colored glue sticks, as well as a method of printing in sugar using the hot glue extruder.
We remember seeing one other LEGO 3D printer. That one didn’t use an extruder either. It placed blocks based on the design to be printed.
Continue reading “Is a LEGO 3D printer by definition self-replicating?”
[J. Benschop] is teaching his nine-year-old son electronics by giving him a few wires, LEDs, and batteries. Eventually, the son looked over at his dad’s workbench and wondered what the little bug-shaped rectangles did. Microcontrollers and embedded programming are just a bit too advanced for someone who hasn’t hit a double-digit age, but [J] figured he could still have his son experience the awesomeness of programming electronics by building a custom electronic Lego microcontroller system.
This isn’t as complex as a Lego Mindstorms system. Really, it’s only an ATMega and a 2.4 GHz wireless transceiver. Still, that’s more than enough to add a few sensors and motor drivers, and an awesome introduction to electronics development. The enclosure for the LegoDuino is, of course, compatible with every Lego brick on the planet. It’s made from a 6×16 plate, three blocks high, with enough room for the electronics, three AA batteries, and the IO headers.
Programming an ATMega, even with the Arduino IDE, is a little beyond the capacity of [J. Benschop]’s nine-year-old son, so he made a few changes to the Minibloq programming environment to support the newly created LegoDuino. It’s a graphical programming language that kids of just about any age can pick up quickly, and with the included RF transceiver inside the ‘Duino, it can even be programmed wirelessly.
It’s an amazing piece of work, and much, much simpler than even the noob-friendly Lego Mindstorms. Not as powerful, though, but when you’re just teaching programming and electronics, you really don’t need much.
Serious research using not-so-serious equipment? We don’t know about that. What’s wrong with using LEGO as a research platform for a Maglev? This team has been doing so for quite some time and with great results.
A Maglev is a vehicle based on the principles of magnetic levitation. Similar poles of magnets repel each other and this concept can be used to create a friction-less track system. But this raises the problems of braking and locomotion. The build log linked above covers the conception in what is the eighth iteration of the research project. But the video below offers the most concise explanation of their approach to these issues.
The researchers are using magnets positioned in trench of the track as a kind of magnetic gear to push against. A series of electromagnets on the Lego vehicle ride in that track. The can be energized, working as a linear motor to push against those permanent magnets. But how do you know which direction of travel this will cause? That problem was solved by adding a hall effect sensor between each electromagnet. Before switching on the coil the hall effect sensors are polled and a timing scheme is selected based on their value. This is used to push the train up to speed, as well as slow it down for braking.
Continue reading “Prototyping a Maglev train using LEGO”
Music used to be delivered on round plastic sheets called Compact Discs. [Ralph] still has some of them lying around which he used in his latest project. It’s a CD changer built out of LEGO pieces. It reminds us of the mid-century jukeboxes that changed out 45s on a record player.
You can’t tell from this image, but the entire disc changer build is shaped to sit atop a computer case. The system is built in two parts. There is a transport arm which moves left and right along the rack of CDs. It uses that black and white strip as an encoder to track its movement. It can reach in, grab a disc, and take it all the way down to the right where it drops it off in a staging area. The second part of the build now takes over, grabbing the disc from the staging holder and rotating it down into the CD tray of the PC. All of this is demonstrated after the jump.
If you’re like us you prefer digital delivery for your music. We haven’t crossed that watershed with video games yet and that’s why we still love this Xbox 360 disc changer hack.
Continue reading “LEGO jukebox choses from different CDs”