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Archive: Electronics

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September 20, 2008

WiFi robot

Jon Bennett created a nifty wireless telepresence bot out of a thrift store RC car, a Linksys WRT54GL router running the Open-WRT Linux firmware, a network camera, and a microcontroller. He's built two variations: one controlled by a PIC microprocessor, and the other controlled by an Arduino. You can use whichever processor you are more comfortable with, and make one of your own for very little cost using this guide.

The goal of this article is to give a high-level overview of the project and provide some implementation details of the software and electronics. It is not meant to be a step-by-step how-to guide, but there should be enough information for someone with motivation and some background knowledge in electronics and software to be able to make their own Wifi Robot. All of the source code is being released under the terms of the GNU GPL v2, so by all means, use the code, and improve it!

This is one of those basic projects that you can take in a number of directions. Jon's guide will get you through interfacing with your typical RC car electronics and controlling it remotely. From here, it's all software. Someone should take a stab at adding an image processing routine on the remote end to create an autonomous sidewalk cruiser.

Wifi Robot

September 19, 2008

Resin casting

Our friend Becky Stern posted a video on Craft today which shows you how to mold and cast small parts out of resin. It's something anyone can do, and the process will allow you to make reproductions of small parts, something that could come in handy when you're prototyping (or designing tiny custom army men).

Casting Resin Rings

September 17, 2008

Stanford Engineering Everywhere

Standford's Stanford's School of Engineering has released a number of Computer Science and Electrical Engineering courses online, in their entirety, called Standford Engineering Everywhere. The online program includes all course materials—notes, tests, and complete lecture recordings—free for students or educators to use under the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported License.

SEE users may pick and choose the materials that best meet their needs and interests. Want a refresher course on a particular programming concept? View a video lecture that covers the basics. Are you a programming novice? Spend several weeks viewing lectures, reading course materials and tackling class assignments. Test your knowledge by taking quizzes and exams.

As an example, here's the first lecture in the Machine Learning course, taught by Professor Andrew Ng:

The ten courses that are available cover a healthy range of topics. It's basically 3 or 4 semesters worth of EE and Comp Sci. education that you can brainload for free. Here's the current selection:

Introduction to Computer Science

Artificial Intelligence

Linear Systems and Optimization

If you've ever wanted to go to Standford, but didn't have the time, money, or grades, here's your chance.

Stanford Engineering Everywhere [via Creative Commons]

Previously
Lecturefox: free university lectures
Bootstrap Education

September 15, 2008

Zoom H2 line input hack - make a 4 channel field recorder

Berto Aussems wrote in from the Netherlends to tell us about his hack which replaces the microphones in the Zoom H2 recorder with 4 line inputs, perfect for 4 channel field recording. The Zoom H2 has gotten a lot of glowing reviews in its standard form, but converting it for line input gives you the flexibility to use external mics and direct input sources for a higher quality recording.

The Zoom H2 is a popular portable soundrecorder. It records HQ audio on the 4 build-in microphones on 4 tracks. This hack makes it possible to switch over to 4 self made line inputs on the back of the device. With a few electronic parts for about 10 USD people can make a 4 channel fieldrecorder.

This 3 minute instruction video shows the way you can make yourself a 4 track field recorder. I don't say its easy....but it can be done in an evening. Now I can record 4 channels from my computer audio interface when the softsynth is running.

This is a pretty affordable modification and the device itself is just short of $200. It might be just the solution for a decent 4 track recorder on a budget, whether you're recording your garage band, environmental sounds, or interviews.

Zoom H2 modification; now with 4 line inputs!

September 10, 2008

HOWTO - make a serial port IR receiver

Alessio Sangalli has been maintaining a guide for a few years that shows you how to create a serial port IR receiver from scratch and use it in both Windows and Linux. Her design is pretty slick since, as you can see from her photo above, the whole package fits neatly inside a standard 9 pin serial connector. There are still plenty of machines that don't have built-in IR support, so this could be handy if you're thinking of turning an old box into a media player or DVR.

How To Build A Simple But Cool IR (Infra Red) Receiver

September 1, 2008

LEGO 3D printer

Gene Hacker created a 3D printer out of LEGO. It's like a lo-rez reprap that operates in polar coordinates instead of the more familiar cartesian system. This is still very alpha and his demos show some promising 3D blobs of frosting. With that in mind, however, most of the basic functionality of a rapid fabrication system is here. Hacker posted the necessaries to Instructables, so you should be able to replicate his design and put your mind to making it even better.

Build a Polar 3-D Printer from Legos [via BoingBoing]

August 24, 2008

Roomba controlled by Wii Balance Board

"Ron" Tajima's Wii Balance Board Roomba looks like a fun way to clean the carpet. The idea is that you surf on the Balance Board, leaning forward or back to steer the robot. The video is a little short on details, but he's using a laptop to read the bluetooth data from the Balance Board and then send control signals to the Roomba bluetooth adapter.

You might recognize Ron from some other Roomba hacks he's done. A while back, he showed how to control the Roomba with the Wiimote (similar to the balance board hack), but the real gem of his collection is Rommba PacMan:

"Ron" Tajima's video channel [via Balance Board Blog]

August 18, 2008

Beagle Board - ultra tiny, 2-Watt Linux system

Hackszine pal Patti Schiendelman tipped me off to the Beagle Board, a spartan little embedded platform, perfect for all things hackable. It's based on the TI OMAP3 processor, which is packaged with 128MB of DDR RAM and 256MB of NAND Flash all on the single chip in the center of the board.

Instead of including things like ethernet and 802.11 on-board, they opted to keep the footprint small and only include the bare essentials: DVI for monitor output, SD/MMC for storage, audio in/out, and USB for device expansion. If you need any other hardware, just get a USB device that has a Linux driver.

Did I mention it's $150 and draws less that 2 Watts? This is definitely what you need for your next autonomous ~~spy~~ weather blimp.

BeagleBoard.org
BeagleBoard Embedded Linux Wiki
Linux Journal - The BeagleBoard: $149 Linux System

August 3, 2008

Magnetic stripe card spoofer

We posted David Cranor's Arduino card reader the other day, and today he wrote in with an even better magstripe hack: a way to simulate a card swipe using an iPod an electromagnet. David writes:

When the card is swiped past the card reader, the changing magnetic field of the passing flux reversals induce a current in the reader element, which is then decoded into binary bits, and the original data stored on the magnetic stripe is reconstructed.
So, in order to emulate a particular magnetic stripe, all we need to do is find a way to recreate the pattern of the way its magnetic field changes as it's being swiped past the reader. How are we going to do this? With an electromagnet!

...

The final piece of this puzzle is how to control the electromagnet. Well, we're trying to recreate a particular waveform of current through the solenoid in order to create a particular waveform of magnetism. What's a common way of storing waveforms and converting them to electric current? Sound files! So, all we have to do is encode the highs and lows representing the desired flux reversal pattern into a .wav file and play it back on an iPod or similar music player through the solenoid.

So between these two howtos, you now know how to read the contents of a magstripe card, encode that data into a wav file, and then simulate a card swipe using that recorded data. For more information on magnetic stripe technology, you should check out "A Day in the Life of a Flux Reversal" by Count Zero, written in 1992 for Phrack #37.

It'd be cool to make a nice looking version of the interface so that you could put all your cards, be they student IDs, bank cards, or gift cards, on your iPhone. My guess, though, is that there's no chance any supermarket checkout attendant would let that simulated card slide. On the bright side, this aught to be a reminder that a thing you have (magstripe card) isn't very sufficient as an identification tool unless it's combined with a thing you know (pin number) or a thing you are (a face that matches the photo on the card).

Magnetic Stripe Card Spoofer
A Day in the Life of a Flux Reversal - Phrack #37

Previously: Decoding magstrip cards with Arduino

August 1, 2008

Decoding magstrip cards with Arduino

Instructables user powerpants created a quick and dirty card reader interface with an Arduino. The Arduino decodes the data from the swiped card and transfers it to a PC over a USB serial connection.

This instructable shows how to use some freely available code, an arduino, and a standard magnetic stripe reader to scan and display the data stored on magnetic stripe cards such as credit cards, student IDs, etc.
I was inspired to post this after reading the intro to magnetic stripe reading and Stripe Snoop that is found in MAKE magazine Volume 1. That tutorial details how to interface a stripe reader to a game port interface, but I have a mac laptop, so I don't have a game port interface!

There are a lot of cool uses for this besides just seeing what kind of personal information is contained on all the cards in your wallet (you'd be surprised). A friend of mine in college once hacked together something like this with Microsoft Word and a bunch of Visual Basic macros to automate computer literacy testing for the whole campus. Students could swipe their student id, the test would start automatically, and when they were finished the results were saved to a database. He was hired to administer all these tests manually, so he basically put himself out of a job after a month and got a promotion.

Arduino Magnetic Stripe Decoder
Magnetic Stripe Reader from MAKE: 01
Stripe Snoop - magstripe research tools

July 27, 2008

Cyber Security Awareness Week

Dan Guido from the Information Systems and Internet Security Lab at the Polytechnic Institute of NYU wrote in about the Institute's 5th annual Cyber Security Awareness Week. If you're in high-school or a college undergraduate program, this is a great opportunity to test your infosec skills against your peers, and hopefully earn a little prize money in the process.

ISIS Lab is organizing NYU-Poly's 5th annual Cyber Security Awareness Week (CSAW) where students can compete and win prizes in a variety of information security challenges. There will be door prizes, raffles for participating, and bonus prizes for undergrad and high school participants. Qualified finalists will receive a travel scholarship to attend the awards ceremony in New York City.

There are a number of events, including an application security "capture the flag" challenge, a security quiz which covers everything from cryptography to risk management, and a 5-day forensics puzzle. There's even an embedded systems challenge where teams are tasked with trying to find hardware and software bugs in a mock control system.

This looks like a lot of fun. Some of the contest materials become available at the beginning of September, so sign up soon if you're interested in participating.

Cyber Security Awareness Week 2008

July 25, 2008

Peggy LED lightboard

MAKE's Collin Cunningham really impressed me with this short film "A Date With Peggy," a story of an overworked hacker finding relaxation through his craft.

After a frustrating day at the office, it feels good to go make something that simply works. (playing with a bunch of ultra-bright LEDs doesn't hurt either)

The Peggy kit from Evil Mad Scientist Laboratories is sort of like a big kid's Light Bright. It's a large 25x25 array that you can wire LEDs into however you like, without worrying about details like load resistors. The LEDs aren't individually addressable, but you do have some programatic control over the whole array, and there's a built in light sensor that you can use to adjust the display based on light conditions.

A Date With Peggy
Peggy kit at the Maker Shed
"Peggy," A Light Emitting Pegboard Display - Evil Mad Scientist

July 19, 2008

Citizen Engineer 01 - SIM card and payphone hacks

Ladyada and PT have kicked off the first episode of their Citizen Engineer video series in style. This episode explores GSM SIM card technology and the more retro tech found inside a retired Bell payphone. Ladyada shows how to create a SIM reader which you can use to do things like read deleted SMS messages or brute-force the card's secret key. In the second part, the team dismantles an old Bell payphone and hacks it to function as a home telephone, require quarters for use, and make Skype calls.

Citizen Engineer

July 17, 2008

Binary Arduino clock

Check out Daniel Andrade's binary LED clock built using the Arduino. It's well thought out, including controls for setting the time and hibernating with the LEDs off. Each hour and minute digit is represented in binary form, so it's actually fairly easy to read once you get accustomed to it.

The circuit and source are available from Daniel's site. If you're ahead of the game and already thinking about what to do this Saturday afternoon, this might be a fun option to add to the list.

DIY: Binary Clock with Arduino

July 9, 2008

Maglite LASER burnination

Desertfoxx sent us a tip to a classic KipKay howto video. It's pretty easy to swap out the diode in a laser pointer or similar laser housing with the diode from an old DVD burner. Put the whole deal into a mini Maglite and you've got yourself a nice little handheld fire starter, perfect for lighting matches or popping dark colored balloons from across the room. Like all lasers, it's also excellent for quickly blinding people, so watch where you point the thing.

If you haven't caught KipKay before, he's been doing some fun weekend project video podcasts for MAKE.

How To Make A Burning Laser Flashlight

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