Hackaday Links: August 18, 2013


Let’s start off with some lock picking. Can you be prosecuted if it was your bird that broke into something? Here’s video of a Cockatoo breaking into a puzzle box as part of an Oxford University study. [Thanks Ferdinand via Endandit]

[Augybendogy] needed a vacuum pump. He headed off to his local TechShop and machined a fitting for his air compressor. It uses the Venturi Effect to generate a vacuum.

Build your own Arduino cluster using this shield designed by [Bertus Kruger]. Each shield has its own ATmega328. Many can be stacked on top of an Arduino board, using I2C for communications.

[Bunnie Huang] has been publishing articles a few articles on Medium called “Exit Reviews”. As a treasured piece of personal electronics is retired he pulls it apart to see what kind of abuse it stood up to over its life. We found his recent article on his Galaxy S II quite interesting. There’s chips in the glass, scuffs on the bezel, cracks on the case, and pervasive gunk on the internals.

We’d love to see how this this paper airplane folder and launcher is put together. If you know of a post that shares more details please let us know.

Squeezing the most out of a tiny microcontroller was a challenge. But [Jacques] reports that he managed to get a PIC 10F322 to play a game of Pong (translated). It even generates an NTSC composite video signal! Watch the demo video here.

3D printed arc reactor replica


[James] just keeps cranking on the idea of the perfect arc reactor replica. This time around he’s made most of the parts using a 3D printer. His write-up covers the basics of the build, but he also used this opportunity to make some tutorial videos on designing the parts using Autodesk 123D.

This is definitely an improvement on his last prop, which was built out of dollar store parts. When designing the components he tried to be as true to the original movie design as possible, while keeping in mind the limitations of using a home 3D printer; he printed them on a Lolzbot AO-101.

The videos below give you a good idea of what it’s like to model parts using 123D. The tool set is pretty simple compared to something like Blender 3D. But [James] uses them in such a way that the components get complex fairly quickly. The second video includes some footage of the parts being printed, as well as the assembly process that adds wrapped wire for looks, and LEDs for illumination.

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Wrist-mounted flamethrower on the cheap


Everyone wants to be Iron Man these days, but without a spare arc reactor lying around, you’ll have to settle on building a backup suit component. [Xavier] documents his take on the wrist-mounted flamethrower in this dirt-cheap and unquestionably dangerous build. Cobbled together from parts found at a local hardware store, this glove has the typical “ready” setting with a small flame that, upon turning one’s wrist, erupts into a loud and large swath of flames. We suspect the mask worn in the video below doubles as identity protection and to prevent accidental hair conflagrations. Skip to the end for a demonstration.

Though not the first flamethrower build at Hackaday, [Xavier's] is the only one with a guide and is certainly the cheapest. Be sure to look into the second generation of the Prometheus flame thrower and its subsequent third version that we featured a couple of years back. Not everyone’s flamethrower is wrist-mounted; some people put them inside a trombone. Remember, don’t try this at home.

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Building an accurate equal arm balance


This interesting take on weights and measures uses a two foot long level as the base for a diy equal arm balance. The balance is the oldest method used for measuring mass. That’s because you don’t even need a reference weight for it to work as long as you are measuring ingredients that are proportional to each other in whole numbers.

The key to accuracy with these scales is to reduce friction at the fulcrum. In this case the fulcrum is made of two upturned razor blades on the base, with a single razor blade resting perpendicular to those on the arm. But because gravity is doing the equalization, the base must be as level as possible. Adjustable feet were added to the base so that it can be leveled on two axes. When the tower at the center was built (using threaded rod) a disc level was used to fine-tune the mounting angle of the two razor blades. The finishing touches include a coupling nut on each end for fine-tuning the balance, and the halves of a tea ball strainer as the weighing vessels.


Liquid nitrogen (finally) makes an Arduino project cool

At $1.5 a liter in Moscow, [Michail] couldn’t resist buying some liquid nitrogen for himself. He thought that because Arduinos were quite popular among geeks, he’d try to overclock one while bringing its temperature down to -196°C/-320°F.

To check the ATmega was still working correctly, [Michail] designed several stability tests: SRAM read/write, flash read, arithmetic math and program flow tests (code with some conditionals). He used a standard HD44780 LCD to view the tests results but also an LED, blinking the number of the test it would have failed. The Arduino was externally clocked by a TTL-logic based square signal generator he designed, which can produce a clock between 16 and 100MHz. It turns out that you can run an Arduino at 65.3MHz when it is cooled with liquid nitrogen!

[Michail]‘s article also explains what happens to the different on-board components when cooled with LN2: electrolytic capacitors becomes virtually non-existent, X7R capacitors’ impedance drop by 2/3, silicon diodes voltage drop increase by 50% and LED’s colors change. Check out the video below:

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Tearing down an ultrasound machine from 1963


Vintage electronics are awesome, and old medical devices doubly so. When [Murtaugh] got his hands on an old ultrasound machine, he knew he had to tear it apart. Even if he wasn’t able to bring it back to a functional state, the components inside make for great history lesson fifty years after being manufactured.

This very primitive ultrasound machine was sold by Siemens beginning in 1963 as a, “diagnostic ultrasound unit for the quick evaluation of cerebral hemorrhage after accidents.” This is barely into the era of transistors and judging from [Murtaugh]‘s teardown, nearly the entire device is made of vacuum tubes, capacitors, and resistors. The only solid state component in this piece of equipment is a bridge rectifier found in the power supply. Impressive stuff, even today.

In the end, [Murtaugh] decided this device wasn’t worth repairing. There were cracks all the way through a PCB, and he didn’t have any of the strange proprietary accessories anyway. Still, this junkyard score netted [Murtaugh] a bunch of old tubes and other components, as well as a nifty CRT that came with a wonderful ‘Made in West Germany’ label,.

AquaTop: a gaming touch display that looks like demon possessed water

AquaTop_touch_displayAre you ready to make a utility sink sized pool of water the location of your next living room game console? This demonstration is appealing, but maybe not ready for widespread adoption. AquaTop is an interactive display that combines water, a projector, and a depth camera.

The water has bath salts added to it which turn it a milky white. This does double duty, making it a reasonably reflective surface for the projector, and hiding your hands when below the surface. The video below shows several different games being played. But the most compelling demonstration involves individual finger tracking when your digits break the surface of the water (show on the right above).

There is also a novel feedback system. The researchers hacked some speakers so they could be submerged in the tank, adding a large speaker with LEDs on it in the same manner. When fed a 50 Hz signal they make the surface of the pool dance.

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