Author: Bryan Cockfield

1832 Articles

Know Your Speed On Rollerblades

February 12, 2015 by 16 Comments

[Anurag] is a computer engineering student with a knack for rollerblading. Rollerblades are not a transportation device that are often fitted with speedometers, so [Anurag] took that more as a challenge and designed this Arduino-powered computer to give him more information on his rollerblade rides.

The device uses an Arduino as the brain, and counts wheel revolutions (along with doing a little bit of math) in order to calculate the speed of the rider. The only problem with using this method is that the wheels aren’t on the ground at all times, and slow down slightly when the rider’s foot is off the ground. To make sure he gets accurate data, the Arduino uses an ultrasonic rangefinder to determine the distance to the ground and deduce when it should be taking speed measurements.

In addition to speed, the device can also calculate humidity and temperature, and could be configured to measure any number of things. It outputs its results to a small screen, but it could easily be upgraded with Bluetooth for easy data logging. If speed is truly your goal, you might want to have a look at these motorized rollerblades too.

Self-Charging Jacket Eliminates Forgetfulness

February 3, 2015 by 23 Comments

Certain parts of the Northern Hemisphere are very, very cold right now. For those of us living in these colder climates, [Aaron] has a simple yet effective hack for keeping your hands warm when you go out for a walk in the brisk cold. He’s wired his jacket up for USB charging so he can make sure his hand warmers are always working.

[Aaron] bought a set of handwarmers that conveniently charge over USB, but he always forgot to actually plug them in once he got home, ensuring that they were always dead. To make his forgetfulness a non-issue, he built the USB charger for the handwarmers into his jacket, but he didn’t just run a wire out of the pocket. The USB charging circuit runs through the coat hanger, using some conductive cloth and steel thread in the inside of the jacket’s shoulders. From there, the cloth makes contact with the metal arms of the hanger and runs out of the hanger to the wall outlet.

This is a great cold-weather hack that might help any forgetful people on the north side of the planet keep warm. You could even use this method to charge batteries used in other wearable electronics. This project is a great reminder that sometimes the best hacks are the simple ones that no one’s thought of yet!

Autonomous Vehicle-Following Vehicle

February 1, 2015 by 36 Comments

Humanity has taken one step closer to Skynet becoming fully aware. [Ahmed], [Muhammad], [Salman], and [Suleman] have created a vehicle that can “chase” another vehicle as part of their senior design project. Now it’s just a matter of time before the machines take over.

The project itself is based on a gasoline-powered quad bike that the students first converted to electric for the sake of their project. It uses a single webcam to get information about its surroundings. This is a plus because it frees the robot from needing a stereoscopic camera or any other complicated equipment like a radar or laser rangefinder. With this information, it can follow a lead vehicle without getting any other telemetry.

This project is interesting because it could potentially allow for large convoys with only one human operator at the front. Once self-driving cars become more mainstream, this could potentially save a lot of costs as well if only the vehicle in the front needs the self-driving equipment, while the vehicles behind would be able to operate with much less hardware. Either way, we love seeing senior design projects that have great real-world applications!

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A Primer On Buck (and Boost) Converters

January 24, 2015 by 13 Comments

We all know that the reason the electrical system uses alternating current is because it’s easy to step the voltage up and down using a transformer, a feature which just isn’t possible with a DC system… or is it? Perhaps you’ve heard of mysterious DC-DC transformers before but never really wanted to look at the wizardry that makes them possible. Now, SparkFun Director of Engineering [Pete Dokter] has a tutorial which explains how these mysterious devices work.

Known as buck converters if they step the input voltage down and boost converters if they step the voltage up, [Pete] explains how these circuits exploit the properties of an inductor to resist changes in current flow. He goes into exquisite detail to explain how components like transistors or MOSFETs are used to switch the current flow to the inductor very rapidly, and just exactly what happens to the magnetic field which makes these devices possible.

The video gives a good amount of background knowledge if you’ve always wanted to understand these devices a little bit better. There are also a few projects floating around that exploit these devices, such as one that uses an AVR microcontroller to perform the switching for a small circuit, or another that uses the interesting properties of these circuits to follow the I-V curve of a solar panel to help charge a bank of batteries. The possibilities are endless!

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Drums Anywhere!

January 16, 2015 by 16 Comments

The students over at Cornell’s School of Electrical and Computer Engineering have been hard at it again with their senior projects. This time, it’s the very tiny and portable drumset dubbed Drums Anywhere by its creators [Shiva Rajagopal] and [Richard Quan]. Since there are other highly portable instruments like roll-up pianos, they suppose there should be a portable drum kit that actually sounds like drums, and this ECE duo have hit the metaphorical and physical drum on the head… except that this project doesn’t actually use physical drums to make sound.

The project consists of two 3D-printed box-like sensors with velcro straps that can be attached to any drumstick-shaped object that might be lying around. Inside the box is a flex sensor and a tiny microphone which report the “beats” to a microcontroller when they strike another object.

On the software side, there are two sampled sounds stored in the microcontroller but they plan to add more sounds in the future. The microcontroller outputs sound to a pair of speakers, and the sensors are sensitive to force, so the volume can range from almost inaudible all the way up to [John Bonham]-style booms. This could also be theoretically expanded to include more than two “beat boxes” for extra sounds, or be wireless. The options are virtually limitless, although the team notes that they are limited by the number of interrupts and ADC converters on their particular microcontroller, an ATmega1284.

This is another interesting take on a having drumset without the drums, and definitely expands the range of what a virtual drum set can do. It’s also great to see interesting projects coming from senior design classes! Be sure to check out the video after the break.

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Keystroke Sniffer Hides As A Wall Wart, Is Scary

January 14, 2015 by 79 Comments

For those of us who worry about the security of our wireless devices, every now and then something comes along that scares even the already-paranoid. The latest is a device from [Samy] that is able to log the keystrokes from Microsoft keyboards by sniffing and decrypting the RF signals used in the keyboard’s wireless protocol. Oh, and the entire device is camouflaged as a USB wall wart-style power adapter.

The device is made possible by an Arduino or Teensy hooked up to an NRF24L01+ 2.4GHz RF chip that does the sniffing. Once the firmware for the Arduino is loaded, the two chips plus a USB charging circuit (for charging USB devices and maintaining the camouflage) are stuffed with a lithium battery into a plastic shell from a larger USB charger. The options for retrieving the sniffed data are either an SPI Serial Flash chip or a GSM module for sending the data automatically via SMS.

The scary thing here isn’t so much that this device exists, but that encryption for Microsoft keyboards was less than stellar and provides little more than a false sense of security. This also serves as a wake-up call that the things we don’t even give a passing glance at might be exactly where a less-honorable person might look to exploit whatever information they can get their hands on. Continue past the break for a video of this device in action, and be sure to check out the project in more detail, including source code and schematics, on [Samy]’s webpage.

Thanks to [Juddy] for the tip!

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Stereo Audio On A PIC32

January 11, 2015 by 13 Comments

The PIC microcontrollers are powerful little devices, and [Tahmid] is certainly pushing the envelope of what these integrated circuits can do. He has built (for educational purposes, he notes) an audio player based on a PIC32 and a microSD card. Oh, and this microcontroller-based audio player can play in stereo, too.

The core of the project is a PIC32MX250F128B microcontroller. 16-bit 44.1kHz WAV files are stored on the microSD card and playback is an impressive 12-bit stereo audio. It can also play back 8-bit files (with some difficulty). [Tahmid] programmed the interface to work through the serial port and it is very minimalistic, mostly because this was a project for him to explore audio on a microcontroller and wasn’t to build an actual stand-alone audio player that he would use from day to day.

Still, even though the project isn’t ready to replace your iPod, the core audio-processing parts are already done if you want to try to build on [Tahmid]’s extensive work. You could even build a standalone audio player like this but have it play high-quality 12-bit stereo audio!

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