Author: Eric Evenchick

299 Articles

Using Google Authenticator With An Arduino

September 14, 2013 by 5 Comments

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).

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ArduGuitar, An Arduino Controllable Guitar

September 10, 2013 by 18 Comments

The ArduGuitar

Electric guitars have several switches and potentiometers for controlling volume, tone, and which pickups are enabled. Rather than fiddling with these by hand, [Bob] built the ArduGuitar. It uses an Arduino to control the parameters over Bluetooth. This allows for musicians to configure presets, then recall them as needed, providing the exact same sound every time. It’s similar to the Guitarduino, but adds wireless control.

The internals of the ArduGuitar consist of the Arduino Micro, a BlueSMiRF from Sparkfun, and resistive opto-isolators. The resistive opto-isolators allow the Arduino to adjust resistance through an electrically isolated barrier. This prevents the Arduino from interfering with the guitar’s sound.

Some of the first Vactrols were used to create a tremolo effect in guitar amplifiers. These pulsed a incandescent lamp onto a photoresistor. Fortunately, there are now integrated solutions. PerkinElmer makes these, and they have a nice application note [PDF] on audio applications.

The final part of the design is an Android app, which provides remote control over Bluetooth. The source for everything is available on Github, and the detailed build log is available here.

Make Your Treadmill More Entertaining For $0

September 7, 2013 by 20 Comments

Treadmill Computer

Treadmills can often be found on the side of the road, after someone gave up on their running regimen and found that the machine was taking up too much space in their basement. This is great for hackers, since they have some useful parts in them.

However, if you’d like to actually use a treadmill for running, some entertainment would certainly help. [KingJackOff] decided to roll his own treadmill entertainment system out of things he had lying around, bringing the total cost to $0.

He took an old laptop and mounted it in a piece of rigid foam using a gratuitous amount of duct tape. With the screen and keyboard mounted, he added speakers and a slot for the DVD drive. Then a printed graphic was taped to the front, with a nice motivational message.

Lots of people have old laptops lying around with mechanical issues. Broken hinges and frames make them unusable, even though the electronics are fine. Some foam and paper could be all you need to bring one back to life.

[via Reddit]

Open Hardware Summit 2013 – Part 1: Demos

September 7, 2013 by 2 Comments

Open Hardware Summit 2013

The 2013 Open Hardware Summit took place on September 6th at MIT. There was a wide array of demos and talks covering Open Hardware methodologies and projects. After the break I’ll be covering the demo area of the conference, and sharing some of my favorite demos.

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Open Activity Tracker Webcast

August 28, 2013 by 2 Comments

livedesign4

The Upverter team loves their FitBit activity tracking devices, but wanted access to raw data. They decided to build their own Open Activity Tracker that would pump data onto an SD card or to a Bluetooth device for processing.

The device uses MPU-9150 motion tracking IC to gather information on movement. This chip combines an accelerometer, gyro, and compass. It also does on-board processing, providing useful data to your host processor over I2C. The only bad news is that it’s a LGA package, which aren’t fun to solder by hand.

The design also has a SD card, Bluetooth module, pressure sensor, and e-ink display. These are all connected to a low power ARM microcontroller.

The team has been webcasting their design sessions, and tonight [Eric Evenchick] (that’s me) will be joining them as they try to cram all of these components onto a PCB. You can watch the live webcast starting at 8:30pm Eastern.

You can watch the previous design sessions after the break.

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Molding Flexible Links

August 28, 2013 by 9 Comments

Flexible Links

Need a custom link that’s strong and flexible? [RobotGrrl] came up with a method of molding flexible links using 3D printed parts and Sugru.

The link consists of two 3D printed hubs, connected by a flexible material cast in a 3D printed mold. [RobotGrrl] recommends using Sugru to create the link, but you can use homemade Oogoo as a low cost substitute. Dish soap is used as a release agent, and prevents the Sugru from sticking to the mold.

The tutorial includes a detailed guide to modeling the parts in Autodesk Inventor, which serves as a quick introduction to the CAD tool. If you just want to make some links, the STL files are available for immediate 3D printing.

Why would you want DIY flexible links? [RobotGrrl]’s Baitbot is a good example. This tentacle robot uses the links as its core. Check out a video of the Baitbot wiggling and jiggling after the break.

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