DIY Microcontroller-switched Power Strip

June 23, 2012 by 22 Comments

switched-power-strip

[Teknynja] was looking for a way to control several discrete AC-powered devices using a microcontroller, and while he did consider the Powerswitch tail 2 from Adafruit, handling 5 devices would get pretty expensive. Rather than buying a complete off the shelf solution, he decided to build his own 5-way switched outlet.

He picked up a sturdy metal power strip from a local hardware store along with some Sharp S201S06V relays he ordered online. After test fitting his relays inside the power strip’s chassis, he wired up 5 of the 6 outlets through them to allow for switching via a microcontroller. He configured the 6th outlet to be live at all times, providing a power source for the control system he planned on using to switch the other receptacles.

[Teknynja] pulled the connector from an old PS/2 mouse for use as a control wire, connecting one wire to each of the relays. He says that the strip is working quite well, and after a few months of use it is holding up nicely.

Checking Out The Temperature Of A Raspberry Pi

June 23, 2012 by 32 Comments

[Remy] has access to a very nice Fluke thermal camera, so when his Raspberry pi came in he pointed the thermal camera at the Raspi (Spanish, Google translation) to see how far this neat computer could be pushed before it overheated.

There are three main sources of heat on the Raspberry Pi: the voltage regulator, the USB/Ethernet controller and the Broadcom SoC. At idle, these parts read 49.9° C, 48.7° C and 53° C, respectively; a little hot to the touch, but still well within the temperature ranges given in the datasheets for these components.

The real test came via a stress test where the ARM CPU was at 100% utilization. The Broadcom SoC reached almost 65° C while the Ethernet controller and regulator managed to reach the mid-50s. Keeping in mind this test was performed at room temperature, we’d probably throw a heat sink on a Raspberry Pi if it’s going to be installed in an extreme environment such as a greenhouse or serving as a Floridian or Texan carputer.

Thanks [Alberto] for sending this in.

CD/DVD Polisher May Save Your Backups Someday

June 23, 2012 by 22 Comments

CD and DVD payers can often keep the music or movie going despite a small scratch. But occasionally you’ll have to skip to the next chapter/track or the player will just give up. But with data back-ups, a scratch can bork a whole set of files. We think that most of the time these headaches can be cured with this simple polisher.

[Wotboa’s] thrift store finds yielded almost all of the components needed to build the device. It’s made up of a couple of motors and a jig. One motor slowly rotates the upturned optical disc while the other spins the polishing pad. That pad is made from felt weather-stripping and is helped along with some plastic polishing compound. [Wotboa] asserts that five minutes in the noisy contraption will work wonders on any disc. You can get an idea of what it’s capable of by watching the video clip after the break.

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DEFCON 20 Tamper Evident Contest Signup

June 23, 2012 by 8 Comments

DEFCON 20 is on its way and if you want to put a team together to compete in the Tamper Evident competition now is the time! The idea of the contest is simple: your team needs to break into something without anyone every knowing. The payload is protected by the best of modern tamper evident techniques. One of the things we really like about the competition is that there are multiple levels so if it’s your first time you DO stand a chance. The number of teams accepted is limited, so don’t wait too long and miss your chance to register.

There’s a ton to be learned from the contest RULES. But perhaps a better primer is going to be [Datagram’s] fifty-two minute talk which we’ve embedded after the break. He was one of the winners of all four contest levels at DEFCON 19 last year.

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Amateur Radio Field Day Is Upon Us

June 23, 2012 by 10 Comments

Looking for something to do this fine Saturday morning? For the US and Canadian readers out there, the fourth weekend in June is amateur radio field day, a day when all the amateur radio and ham geeks get together, string up a few antennas, and do their yearly community outreach/contact as many other radio heads as possible.

This weekend, there are more than 1600 field day events taking place all across the US and Canada. Odds are, you’re not more than a half hour drive from a field day event; you can find the closest one with the AARL’s handy Google Map of field day locations.

Since last year, we’ve seen a whole host of cool stuff to do with radio including a $20 software defined radio. If getting your license is too big of a step for you right now, you could at least plug a USB TV tuner dongle into your computer and see what is possible with radio. As a neat little bonus, you don’t even need a license for SDR. You might need a better antenna, and the ham guys at field day will be more than happy to point you into the right direction.

A Primer On Dynamic Loading

June 22, 2012 by 7 Comments

[Graphitemaster] is helping to demystifying the process of tailoring functions for dynamic loading. His tutorial shows how make a dynamic function that prints “Hello World” to the standard output. This is of course rudimentary, but if you have no prior experience with the topic you might be surprised at what actually goes into it.

Normally your compiled code has addresses in it that tell the processor where to go next. The point of dynamic loading is that the code can be put anywhere, and so static addresses simply will not work. The code above shows how a simple printf statement normally compiles. The callq line is a system call that needs to be replaced with something that will play nicely in the registers. [Graphitemaster] takes it slow in showing how to do this. Of course a dynamic function alone isn’t going to be much good. So the tutorial finishes by illustrating how to program a dynamic code loader.

Bring Your LED Matrix Project Into The Living Room

June 22, 2012 by 6 Comments

If you’re able to make a project look this good it shouldn’t be hard to convince that significant other to let you install it in a prominent place in the house. We think [Greg Friedland] pulled this off perfectly by building a 4’x8′ tablet controlled LED matrix.

First of all, everything looks better in a shiny case. It shouldn’t come as a surprise that this looks nice, thanks to the face plates which are mounted in a way that gives them a modern style (we’d expect to see this hanging in Ikea). They’re acrylic diffuser panels meant for used with lighting in a suspended ceiling. They do a nice job of scattering the light put off by the 544 LED modules that make up the display. The wiring was made easy by using LED strands where each pixel has its own control chip (WS2801). It sounds like the display will peak at around 160 Watts, which isn’t really that much considering the area. One nice touch that’s shown off in the video after the break is a full-feature iPad interface that even allows you to paint in light using your finger. But we’re also satisfied that [Greg] posted about the physical build too.

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