Guest Post: Try Radar for Your Next Project

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(photo taken by Matt Metts)

Sensors. The low-end stuff that we can get our hands on usually suffers from poor range, lack of sensitivity, and no way to characterize what the target is. But today we can use the good stuff that, until recently, was only available to military: radar. In this post we will discuss how radar works, commercially available small radar devices, and where to learn more to help make it easy to add radar to your next project. Reach out and sense something!
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We’re Going To The Midwest RepRap Fest

One month from now, Goshen, Indiana – deep in the land of Dairy Queens – will become one of the premier sites for RepRapping, 3D printing and everything involving open source manufacturing. It’s the 2nd annual Midwest RepRap Festival to be held March 14-16. Oh, Hackaday will also be there, cavorting around, distributing some swag, and doing some live videos and posts of the event.

Highlights of the Festival include [Prusa] giving a talk on the state of open source printing, [Sonny Monicou] discussing the challenges of his RepRap workshops, a roundtable discussion of the RepRap project, [Nicholas Seward] and his creations – the Wally, Simpson, and Lisa, along with a few folks from Lulzbot and UltiMachine. Basically, the only way to go to a bigger RepRap convention would be to visit a Maker Faire, and even that would only add a few hundred 9-year-olds astounded by printed Minecraft figurines.

If you’re willing to make the drive, there’s no fee to attend; just register, show up, and you’ll get a table for all that up-til-midnight RepRapping. There’s also a waffle breakfast on Sunday, along with me walking around makin’ it rain Hackaday stickers.

Arduino Powered ECG Informs Users of Their Death

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Just when you thought you’d seen an Arduino do everything, [birdyberth] built an Arduino powered Electrocardiogram (ECG or EKG). Electrocardiography is a non invasive method of studying the heart. For many of us that means a 10 minute test during our yearly physical exam. Medical grade ECGs can use up to 10 electrodes. To keep things simple [birdyberth] went the route of a few circuits we’ve seen before, and reduced it to two electrodes and a ground reference. [birdyberth] makes note that the circuit is only safe if battery power is used.

The “heart” of any ECG is an instrumentation amplifier. Instrumentation amplifiers can be thought of as super differential amplifiers. They have buffered inputs, low DC offset, low drift, low noise, high open loop gain, and high impedance among other favorable characteristics. The downside is cost. A typical op amp might cost 0.50 USD in single piece quantities. Instrumentation amplifiers, like [birdyberth's] INA128 can cost $8.30 or (much) more each. The extra cost is understandable when one thinks about the signals being measured. The ECG is “picking up” the heart’s electrical signals from the outside on skin. On commonly used ECG graph paper, a 1mm square translates to about .1 mV. High gain and clean signals are really needed to get any meaningful data here.

Electrodes are another important part of an ECG. Medical grade ECG units typically use disposable adhesive electrodes that make a strong electrical connection to the skin, and hurt like heck when they’re ripped off by the nurse. [birdyberth] was able to make electrodes using nothing more than tin foil and paper clips. We think the real trick is in the shower gel he used to make an electrical connection to his skin. While messy, the gel provides a low resistance path for the tiny currents to flow.

The actual processing in [birdyberth's] circuit is easy to follow. The signal from the instrumentation amplifier is sent through a low pass filter, through a 741 op amp, and then on to the Arduino. The Arduino uses a 16×2 LCD to display heart rate in beats per minute, along with a friendly message informing you if you are alive or dead. The circuit even provides audible feedback for heart beats, and the classic “flatline tone” when the users either disconnects the electrodes or expires. [birdyberth] has also plugged in his pocket oscilloscope just after the low pass filter. As his video shows, the familiar ECG waveform is clearly visible. We’d love to see a more complex version of this hack combined with [Addie's] heart simulator, so we could know exactly which heart malady is killing us in real time!

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Yo Fish, We Pimped Your Tank

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[Studio Diip] a machine vision company based in The Netherlands has created fish on wheels, a robotic car controlled by a goldfish. The idea of giving fish mobility on land is nothing new, but this definitely is a novel implementation. A Logitech 9X0 series camera captures overhead images of the fish tank. The images are then fed into a BeagleBoard XM, where they are processed. The image is thresholded, then a centroid of the fish-blob is determined. With the current and previous blob locations known, the BeagleBoard can determine the fish’s swim direction. It then and commands the chassis to drive accordingly.

The system appears to work pretty well on the video, however we’re not sure how much of the input is due to the fish swimming, and how much is due to the water sloshing and pushing the fish around. We definitely like the chrome rims and knobby tires on the fishes’ pimped out ride.  This could become a trend. Just make sure no animals or humans are hurt, and send your animal powered hacks to our tip line!

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Hackaday Terms of Use (aka: The Lawyers are Coming!)

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Hackaday has posted Terms of Use and Privacy Policy documents which you should read. These can also be accessed through the Policies Page which is linked in the footer. We’ve edited this post to take up less room since it will be sticky for a few days. Original text and updates after the jump.

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Hackaday Visits The Clark Magnet High School

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Thought Hackaday’s trip to LA was all about hackerspaces, parties, and rummaging through piles of awesome junk? Nope. We’re also tasked with some community outreach that brought us to the Clark Magnet High School in Glendale, CA.

This isn’t your usual high school. Each year, it accepts around 300 new freshmen (grade 9) from the other high schools in the Glendale district. Selection is done through a lottery system, ensuring it’s not just the kids “on the good side of the tracks” or whose parents are active in the PTA that are selected; about 52% of the students at Clark can be classified as at or below the poverty line.

The curriculum? Instead of stopping at the classical comprehensive high school education, the students at Clark Magnet are focused primarily on the STEM fields. They’re also the home base for Team 696, a FIRST robotics team that has done very well in robotics competitions. A few mentors from JPL and IBM help the students out on their projects, and the head of Clark’s engineering program, [David Black], as well as the principal, were once students themselves.

As far as their engineering program goes, they have a very impressive setup; their workshop features a Haas minimll with a 10-tool carousel, a huge CNC wood router, more than one 3D printer, a small woodshop, a CAD classroom – in short, enough tools to make just about anything. Because Clark Magnet is in sunny California, they’ve been able to get a few grants and build a 358kW peak solar array behind the football field. It’s enough to keep the lights on, and the electric bill down, allowing them to hire an additional teacher or two.

In addition to an impressive engineering/shop class, there’s also an audio and video production suite filled with Mac Pros, cameras, mixing boards and 96 Terabytes of storage. It’s not an exaggeration to say this high school is better equipped than some colleges.

Clark also does some other very interesting stuff outside of class; they’ve launched and recovered high altitude balloons, traveled to elementary schools to play with Lego robots, and some students also have impressive home-built projects they bring in to tinker with. We saw a homebrew quadcopter and a very awesome Mecanum wheel robot that we expect to see in the Hackaday tip line shortly.

Despite how awesome the Clark engineering department is, and how capable the students are, they’ve said the FIRST robotics team has been getting a lot of flak from the rest of the maker community. Apparently some people see an amazing engineering program as a waste of resources. From our short time at Clark, we think nothing could be further from the truth. These students are quickly becoming experts at CAD design and CNC operations. They’re competent embedded programmers and well on their way to becoming awesome engineers. Students who don’t want to build a robot or program firmware get involved in project planning, marketing, and all the rest of the business that goes into running a initiative of this size. It’s a truly awesome program, and I have to say I’m a little bit jealous I didn’t graduate from Clark.

Gallery of pics and two videos below: going over the workshops at Clark and a robot project. Our fanboyism for Clark also demands we link to the (very small and very resonable) Kickstarter the FIRST robotics team is using for their 2014 budget.

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The Gathering: Huge Success!

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In case you haven’t heard, Hackaday put on a little shindig in downtown LA this past Tuesday. It was awesome.

And we had a few very awesome visitors: [Eliot], senior editor of Hackaday for the first five years made a showing, as did former co-editor [Jack Buffington]. Eminent LA-area hackers came out, including [charliex] of Null Space Labs, the guys from Deezmaker, and the long-haired hippie who can be found in a few NASA videos for the Curiosity rover.

Aside from the free drinks and the awesome people, there was some really cool tech on display. The mezzanine of the bar had a laser graffiti rig, and everyone who came received a super collectible NFC card that allowed them to vote on what Hackaday is doing for our next main event (the quadcopter option won but the vote was non-binding so we’ll keep you updated).

On a personal note, this was one of the few times I’ve interacted with Hackaday readers without the use of a keyboard. You guys are awesome. Thanks for coming out, and if you have any pics from the party, post a link to an album in the comments, or share your stories with us on Twitter via #HaDLAGoogle+, and/or Facebook.

Pics below. These were taken by [Edward de la Torre]

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