An RTL-SDR Spectrum Analyzer

With the combination of small, powerful, and pocketable computers and cheap, off-the-shelf software defined radio receivers, it was only a matter of time before someone built a homebrew spectrum analyzer with these ingredients. This great build is the project of [Stephen Ong] and he’s even released all the softwares for you to build this on your own.

The two main components of this build are a BeagleBone Black and its 7″ Touchscreen cape. The BeagleBone is running Angstrom Linux, a blazingly fast Linux distro for small embedded devices. The radio hardware consists of only a USB TV tuner supported by RTL-SDR. In his demo video, [Stephen] shows off his project and by all accounts it is remarkable, with a UI better than most desktop-oriented SDR software suites.

You can grab the BeagleBone image [Stephen] is using over on his blog, but for more enterprising reader, he’s also put up the source of his ViewRF software up on GitHub.

Handmade Stainless Steel Chainmail

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We know that armor making is an art form. We know it. Still… it’s really easy to let yourself think that making a chain mail shirt is easy after seeing the skills [KdogCrusader] throws down in this build. His hauberk isn’t quite finished yet, though we don’t blame him from wanting to show off the work having put so much into it.

The process starts with fifty pounds of stainless steel wire. That’s the coil suspended on a rod in the upper left. It’s fed into his hacked together coiling jig where it is wound into coils that set the diameter of the rings (think long springs that aren’t springy). Coils are cut along one side resulting in that mountain of individual rings. From there it’s a matter of interlinking all of the rings. He cut apart an old T-shirt to use as a pattern during the assembly. So far the front and the back are only connected at the shoulders as he has yet to add sleeves and finish the sides.

[via Reddit]

3D Printed Prosthetic Hand

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3D printing – with the promise of low-scale manufacturing and custom parts – is ideal for the prosthetic industry, but so far prosthetic hands have been a very, very hard nut to crack. [Joel] has been working on the Open Hands Project, a project that aims to make robotic prosthetics accessible to makers, researchers, and amputees alike.

Even though the mechanisms inside the hand are fairly simple – DC gear motors retracting steel cable ‘tendons’ – [Joel] was able to pack all this equipment into a very small volume that isn’t much bigger than real, meat-based hands. To actuate the mechanical muscles in the hand, the user simply flexes a few muscles in their forearm. These electrical signals are picked up by a suite of custom electronics and tell the Open Hand what to do

In [Joel]’s Indiegogo video, he goes over what makes his robohands work with a little help from [Liam Corbett], hand amputee. Aesthetically, the Open Hand is a big improvement over [Liam]’s two-pronged hook, and with the dexterity demonstrated in the video, possibly a lot more capable.

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Hackaday Links: September 8, 2013

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“I’m sorry Dave, I’m afraid I can’t open the dorm room door.” Does your dorm room have a peephole? Take [pjensen’s] lead and turn it into a mini HAL 9000 using a red LED.

Mix a little work in with your hobby skills. [Vittore] needed to build a video looper to drive some TV screens for a Hotel contract job. He grabbed a Raspberry Pi and got to work. The final product (translated) even uses a shared folder on the hotel’s network as the source slides.

We’re not sure if anyone noticed last Monday (it was Labor Day in the U.S.).  We had a little fun with coffee themed posts. [Tom] wrote in to remind us about the HTCPCP: Hyper Text Coffee Pot Control Protocol. If you don’t have time to read it all, he suggests you don’t miss his favorite, error code 418.

Maybe funny reading isn’t your thing right now, but we have some more helpful stuff to offer. Check out [John Chandler’s] Commandments for using PIC microcontrollers from a few years back.

[Andy] has some old smart phones which he is using in his projects. His beef with the touchscreens is that there’s no tactile feedback. Since these are going to be dedicated displays he’s outlining the touch controls with tape to let your finger know what it’s doing.

If you’re living in your first home in America there’s a really good chance it’s a 1950’s ranch house considering how many of them were built after World War II. Bring its infrastructure into the information age with a cable retrofit. [Andrew Rossignol] just did so and posted a lot of pictures of the process.

If you liked [Ken Shirriff’s] post about the Sinclair Scientific Calculator we think you’ll love his continuation of a Z80 reverse engineering series.

Use Your New-timey Printer To Make An Old-timey Camera

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Here’s something to show people who don’t realize the power of 3D printing. This pinhole camera has one moving part which reveals the pinhole, letting in light to expose the 4×5 film inside.

It’s a near perfect roundup of all the qualities a 3D printer has to offer. The build centers around a 4×5 film holder which can be acquired used or as surplus. This drives home the concept of having the power to replace parts (in this case the entire camera) that fit with existing pieces (the film holder). The picture above is big enough that you can see the layers on the pyramid shape, but the structural pieces around the frame also let the uninitiated see that you can print more than just solid blocks. And finally, since it’s up for download on Thingiverse its a good example of how the printing community shares and builds on each others’ work.

Does it take quality photos? We have no idea. So far we didn’t see any example pictures. But really, if you’re looking for top quality you might want to build your own digital camera. Here’s one that uses a 14 megapixel sensor.

We’re Hiring

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The title says it all. We need more writers to keep the fresh hacks coming, now’s your chance to apply for the job.

UPDATE: Thank you for all of the applications. I have made the first round of offers to a select few. Narrowing it down to a handful was difficult as so many highly qualified, avid readers sent in applications. You are still welcome to submit an application which we’ll keep on file, but I don’t anticipate making any more offers at this time.

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BREWSTER Fetches Your Beer Automatically

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Afraid that if you leave the room you’ll miss the best play of the game? Now you don’t need to move your rear end in order to grab the next brewski. BREWSTER was developed to fetch cold beers from the fridge and deliver them to you automatically.

The robot started as a roomba but has been heavily repurposed with the addition of a mechanical arm on top of the chassis. This not only lets BREWSTER grip a can of beer, but it can first open the mini fridge and reach far enough inside to get one from the back. This requires no modification to the refrigerator, but the low clearance of the roomba does call for a mini-fridge sitting at floor level. Check out a demo run in the video after the break. We think the current version is running on a pre-coded route; this project is just waiting for a spin-off that has mapping and machine vision.

The alternative to this single can delivery would be to make the entire icebox into a robot.

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