Ham Radio Trips Circuit Breakers

February 6, 2017 by Elliot Williams 66 Comments

Arc-fault circuit breakers are a boon for household electrical safety. The garden-variety home electrical fire is usually started by the heat coming from a faulty wire arcing over. But as any radio enthusiast knows, sparks also give off broadband radio noise. Arc-fault circuit interrupters (AFCI) are special circuit breakers that listen for this noise in the power line and trip when they hear it. The problem is that they can be so sensitive that they cut out needlessly. Check out the amusing video below the break.

Our friend [Martin] moved into a new house, and discovered that he could flip the breakers by transmitting on the 20-meter band. “All the lights in the place went out and my rig switched over to battery. I thought it was strange as I was certainly drawing less than 20 A. I reset the breakers and keyed up again. I reset the breakers again and did a [expletive] Google search.” Continue reading “Ham Radio Trips Circuit Breakers” →

Amazing 3D-Scanner Teardown And Rebuild

February 6, 2017 by Elliot Williams 14 Comments

Pour yourself a nice hot cup of tea, because [iliasam]’s latest work on a laser rangefinder (in Russian, translated here) is a long and interesting read. The shorter version is that he got his hands on a broken laser security scanner, nearly completely reverse-engineered it, got it working again, put it on a Roomba that was able to map out his apartment, and then re-designed it to become a tripod-mounted, full-room 3D scanner. Wow.

The scanner in question has a spinning mirror and a laser time-of-flight ranger, and is designed to shut down machinery when people enter a “no-go” region. As built, it returns ranges along a horizontal plane — it’s a 2D scanner. The conversion to a 3D scanner meant adding another axis, and to do this with sufficient precision required flipping the rig on its side, salvaging the fantastic bearings from a VHS machine, and driving it all with the surprisingly common A4988 stepper driver and an Arduino. A program on a PC reads in the data, and the stepper moves another 0.36 degrees. The results speak for themselves.

This isn’t [iliasam]’s first laser-rangefinder project, naturally. We’ve previously featured his homemade parallax-based ranger for use on a mobile robot, which is equally impressive. What amazes us most about these builds is the near-professional quality of the results pulled off on a shoestring budget.

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Plywood Steals The Show From Upcycled Broken Glass Art Lamps

February 4, 2017 by Elliot Williams 23 Comments

You can tell from looking around his workshop that [Paul Jackman] likes plywood even more than we do. And for the bases of these lamps, he sandwiches enough of the stuff together that it becomes a distinct part of the piece’s visuals. Some work with a router and some finishing, and they look great! You can watch the work, and the results, in his video embedded below.

The plywood bases also hide the electronics: a transformer and some LEDs. To make space for them in the otherwise solid blocks of wood, he tosses them in the CNC router and hollows them out. A little epoxy for the caps of the jars and the bases were finished. Fill the jars with colored glass, and a transparent tube to allow light all the way to the top, and they’re done.

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33C3: Memory Deduplication, The Hacker’s Friend

February 4, 2017 by Elliot Williams 11 Comments

At the 33rd annual Chaos Communications Congress, [Antonio Barresi] and [Erik Bosman] presented not one, not two, but three (3!!) great hacks that were all based on exploiting memory de-duplication in virtual machines. If you’re interested in security, you should definitely watch the talk, embedded below. And grab the slides too. (PDF)

Memory de-duplication is the forbidden fruit for large VM setups — obviously dangerous but so tempting. Imagine that you’re hosting VMs and you notice that many of the machines have the same things in memory at the same time. Maybe we’re all watching the same cat videos. They can save on global memory across the machines by simply storing one copy of the cat video and pointing to the shared memory block from each of the machines that uses it. Notionally separate machines are sharing memory. What could go wrong?

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Well, That Was Quick: Heng Lamp Duplicated

February 4, 2017 by Elliot Williams 20 Comments

That didn’t take long at all! We covered a pretty cool lamp with a novel magnetic switch mechanism, and [msraynsford] has his version laser cut, veneered, a video posted on YouTube (embedded below), and an Instructable written up before we’d even caught our breath.

For those who missed it, the original Heng lamp is a beautiful design with a unique take on a magnetic switch. As with the original, the secret sauce is a switch inside that’s physically held closed by the two magnets. It’s a pretty clever mechanism that looks magical to boot.

[msraynsford]’s version replaces the floating spheres with floating cylinders, which are easier to fabricate in layers on a laser cutter, but otherwise the copy is fairly true to the aesthetics of the original. Pretty sweet!
Continue reading “Well, That Was Quick: Heng Lamp Duplicated” →

Valentine’s Heart With Awesome Animations

February 3, 2017 by Elliot Williams 3 Comments

January has drawn to a close, and for many of you that means: “Oh no! Less than two weeks’ time until Valentine’s day.” But for us here at Hackaday, it means heart-themed blinky projects. Hooray!

[Dmitry Grinberg] has weighed in with his version of the classic heart-shaped LED ring. It’s hard to beat the BOM on this one: just a microcontroller, five resistors, and twenty LEDs. The rest is code, and optionally putting the name of your beloved into the copper layer. Everything is there for you to download.

Continue reading “Valentine’s Heart With Awesome Animations” →