The base of his device is a couple of very large ring magnets that would most often be used in speakers. It’s hard to see them in the image above because there’s an inverted plastic container obscuring them. A second (or third depending on how you’re counting) ring magnet is selected because it is smaller than the circular void in the magnetic base. It’s impossible to simply balance the magnet in the air, but spinning it is a different story. By creating a perfectly balance magnetic top, then spinning it inside the magnetic field of the base, you can leave it floating in mid-air.
Check out the video after the break. It’s a neat effect, but you really do have to have a perfect setup for it to work. [Andrey] mentions that it takes a couple of hours to fine-tune. And if the ambient conditions change slightly, it throws the whole thing off.
When you think about hacking laptops, it’s highly unlikely that you would ever consider the battery as a viable attack vector. Security researcher [Charlie Miller] however, has been hard at work showing just how big a vulnerability they can be.
As we have been discussing recently, the care and feeding of many batteries, big and small, is handled by some sort of microcontroller. [Charlie] found that a 2009 update issued by Apple to fix some lingering MacBook power issues used one of two passwords to write data to the battery controllers. From what he has seen, it seems these same passwords have been used on all batteries manufactured since that time as well. Using this data, he was subsequently able to gain access to the chips, allowing him to remotely brick the batteries, falsify data sent to the OS, and completely replace the stock firmware with that of his own.
He says that it would be possible for an attacker to inject malware into the battery itself, which would covertly re-infect the machine, despite all traditional removal attempts. Of course, replacing the battery would rectify the issue in these situations, but he says that it would likely be the last thing anyone would suspect as the source of infection. While using the battery to proliferate malware or cause irreversible damage to the computer would take quite a bit of work, [Charlie] claims that either scenario is completely plausible.
He plans on presenting his research at this year’s Black Hat security conference in August, but in the meantime he has created a utility that generates a completely random password for your Mac’s battery. He says that he has already contacted Apple to in order to help them construct a permanent fix for the issue, so an official patch may be available in the near future.
A few months ago, we covered Radio Shack’s efforts to suck less, and the Radio Shack DIY team has now come back with the top ten suggestions submitted. Of course Arduinos make the list at number 1, which we somewhat expected for beginner projects. Here’s the entire list in order:
There’s very few users out there who actually have their hands on an Open Pandora Console. But the ones who do might find this hack useful for getting TV out up and running. It’s actually not hard at all, but if you don’t want to alter the hardware on the device you’ll first have to find a cable plug that will fit the EXT jack. This proved more difficult than it needed to be, since TI carries the connector but only sells them in multiples of 2200. A group buy was organized and we’d bet you can still get in on that action.
The connector in question carries TVout1 and TVout2 conductors. These correspond to the Luminance and Chrominance signals needed for the S-video protocol. But [MarkoeZ] wanted to use a composite connection. Turns out that’s not hard either, he hooked up the ground from the plug to the ground of the RCA jack, then connected both video lines to the center conductor, making sure to add an inline 470pf capacitor on the Chrominance side. Check out the demo video embedded after the break to see the final product.
Pulse Width Modulation is definitely the preferred method of dimming an LED with a microcontroller, but we were interested in hearing about a different method called Binary Code Modulation. BCM does the same thing as PWM, it turns the LED on and off very rapidly so that your eye cannot detect a flicker. The brightness level is a result of the average amount of time the LED is on versus when it is off. This is called duty cycle and although it can be the same percentage for both PWM and BCD, there is a fundamental difference.
While PWM usually uses a cyclical on/off cycle (30% on, 70% off, repeat) BCD uses a cumulative cycle. As you can see above, each successive bit of binary code carries double significance compared to the previous bit. Now just assign a duty cycle based on your precision, and have an interrupt fire for each bit of the counter. The graph above shows some highs and some lows combining to reach the target duty cycle. An interrupt is used for each bit, and pin changes are made in the service routine.
The benefit of this system is that it is scaleable without adding overhead. You’re already running the interrupts so servicing 8 or 128 LEDs doesn’t have vastly different needs as it would with PWM. The big downside is that the more bits of precision you use, the faster your processor must run so that the eye doesn’t detect the lengthy on or off cycles of the higher bits as visible flickering.
The build uses cheap decimal thumbwheel switches he bought on eBay. Each switch is wired up with resistors for each digit, and each switch is wired up in series. The result is a small, easy to read resistor box with a range of 1 Ω to 10 MΩ.
[Eric] and the crew over at The Tech Junkies, just put the finishing touches on a pretty powerful robot that they call “Mantis”.
The six wheel, chain-driven robot is pretty impressive at first glance. The robot is centered around a Netduino, which controls four 60 amp speed controllers. The speed controllers are tasked with driving four beefy CIM motors, which propel the robot along at a pretty decent tick.
For the project, the team designed their own controller application called IPGamepad, which allows the robot to be controlled by any Android device. The interface is pretty simple as you can see in the video below, making it quite easy to control the bot.
While the Mantis was not a cheap production by any means, it does look like a ton of fun to drive. The crew will be taking this robot along with 2 others out to Maker Faire Detroit, so be sure to swing by and say hello if you’re in the area.
[DJ Sures] got his hands on a plastic Wall-E toy and decided to build a robot that includes a camera, voice recognition, and object tracking. The result is adorable so we’re putting this video before the break:
