Robot Bites Man!

The old newspaper saying holds that a dog biting a man isn’t news, but “Man Bites Dog” is a stellar headline. So instead of focusing on the usual human-on-small-robot torture experiments as we usually do, we bring you “The First Law“, an art piece by [Alex Reben].

[Alex] built a robot that “intentionally” defies Asimov’s First Law: doing no harm to humans. A human puts its little pink finger in the slot, is sensed, and a robot arm with a needle comes down and smashes through the meatbag’s puny fleshy appendage. Or maybe it doesn’t — it’s got a randomization routine that can be said to be “choosing” to prick you or not.

Yeah, the pin-prick is trivial, and yeah, the robot is not really deciding, but the point of the ‘bot is to get people talking. In a world where killer robots are not (yet, explicitly) against the Geneva Convention, soon we’re going to be facing this problem for real. If we need robot-art that makes literary references to get us thinking about these issues, so be it.

Of course, you don’t need to wait until there’s moral consensus to build your own terribly dangerous “robots” at home. How about an automated flamethrower or a knife-wielding tentacle? Or maybe this once, we’ll say that it makes more sense to just sit back and read about other folks doing it.

Via [Fast Company]. Thanks [fishocks367] for the tip!

A Toasty Warm Pool Without The Propane Bills

So, you’ve got the deck, you’ve got the pool and the lounger, you’ve got the summer, and you’ve got the piña colada. All set, you might say.

Sounds idilyic, but sadly we aren’t all lucky enough to live in a tropical climate. So while sipping the cocktail on the lounger you’d be warm enough the chances are that taking a dip would leave you feeling as though you’d just jumped into the Arctic Ocean. Not a problem, just turn on the pool heater. At this point you discover just how much it costs to heat a large body of water kept outdoors and open to the atmosphere. You become the kind of valued customer your liquid propane dealer sends a Christmas card to, you are reduced to living on a diet of budget ramen, and your children wear shoes with holes in them.

[ClanMan] had almost the problems outlined above, at least as far as the uncomfortable propane bills. His solution was a surprisingly simple one, he built himself a solar water heater from inexpensive PVC pipe.

It might not be immediately apparent to the uninitiated, but the key to making an efficient solar collector from such a basic material lies in careful selection of the bores of the various sections of pipe being used. The hot water feed from the propane heater had quite a narrow bore with a fast flow rate, but because [ClanMan] needed his water to linger in the collector and pick up as much solar heat as possible, he chose a much wider bore to feed it to ensure a much slower flow. The collector itself was made from multiple parallel lengths of much narrower pipe, to preserve the slow net flow across their combined cross-section while ensuring the maximum surface area contact between hot pipe and water.

The resulting heat helped take the temperature of his pool from 75 to 80 Farenheit. This may not sound like much, but was enough to make a noticeable difference.

We’ve featured quite a few solar heat projects before here at Hackaday. Best title has to go to the Hippie-Redneck Solar-Heated Kiddo Swimmin’ Pool And Hot Tub, but we’ve also featured a very tidy coiled solar collector. All this swimming is hungry work though, so how about a solar cooker made from a satellite dish?

Wheel of Resistors Form Unique Rotary Encoder

Continuing his tradition of making bits of wire and scraps of wood work wonders, [HomoFaciens] is back with a unique and clever design for an electromechanical encoder.

There are lots of ways to build an encoder, and this is one we haven’t seen before. Not intended in any way to be a practical engineered solution, [HomoFaciens]’ build log and the video below document his approach. Using a rotating disc divided into segments by three, six or eight resistors, the encoder works by adding each resistor into a voltage divider as the disc is turned. An Arduino reads the output of the voltage divider and determines the direction of rotation by comparing the sequence of voltages. More resistors mean higher resolution but decreased maximum shaft speed due to the software debouncing of the wiped contacts. [HomoFaciens] has covered ground like this before with his tutorial on optical encoders, but this is a new twist – sort of a low-resolution continuous-rotation potentiometer. It’s a simple concept, a good review of voltage dividers, and a unique way to sense shaft rotation.

Is this all really basic stuff? Yep. Is it practical in any way? Probably not, although we’ll lay odds that these encoders find their way into a future [HomoFaciens] CNC build. Is it a well-executed, neat idea? Oh yeah.

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Prusa Shows Us the New i3 MK2 3D Printer and Where the Community is Headed

Josef Prusa’s designs have always been trustworthy. He has a talent for scouring the body of work out there in the RepRap community, finding the most valuable innovations, and then blending them together along with some innovations of his own into something greater than the sum of its parts. So, it’s not hard to say, that once a feature shows up in one of his printers, it is the direction that printers are going. With the latest version of the often imitated Prusa i3 design, we can see what’s next.

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Wrangling High Voltage

Working with high voltage is like working with high pressure plumbing. You can spring a leak in your plumbing, and of course you fix it. And now that you’ve fixed that leak, you’re able to increase the pressure still more, and sometimes another leak occurs. I’ve had these same experiences but with high voltage wiring. At a high enough voltage, around 30kV or higher, the leak manifests itself as a hissing sound and a corona that appears as a bluish glow of excited ions spraying from the leak. Try to dial up the voltage and the hiss turns into a shriek.

Why do leaks occur in high voltage? I’ve found that the best way to visualize the reason is by visualizing electric fields. Electric fields exist between positive and negative charges and can be pictured as electric field lines (illustrated below on the left.) The denser the electric field lines, the stronger the electric field.

The stronger electric fields are where ionization of the air occurs. As illustrated in the “collision” example on the right above, ionization can happen by a negatively charged electron leaving the electrically conductive surface, which can be a wire or a part of the device, and colliding with a nearby neutral atom turning it into an ion. The collision can result in the electron attaching to the atom, turning the atom into a negatively charged ion, or the collision can knock another electron from the atom, turning the atom into a positively charged ion. In the “stripping off” example illustrated above, the strong electric field can affect things more directly by stripping an electron from the neutral atom, again turning it into a positive ion. And there are other effects as well such as electron avalanches and the photoelectric effect.

In either case, we wanted to keep those electrons in the electrically conductive wires or other surfaces and their loss constitutes a leak in a very real way.

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Hackaday Advises the United Nations

The Convention on the Rights of Persons with Disabilities is being held this week at the United Nations in New York and Hackaday will be there. Sophi Kravitz is representing us as the conference discusses assistive technology.

Sophi’s panel is Thursday mid-day, entitled: Tec Talk: Brilliant New Designs in Assistive Technology, Ease of Use & Multimedia. The Hackaday community has become a world leader in thinking about new designs, implementations, and increased availability of assistive technologies. We’re really excited to have an organization like the UN recognize this trait. Congratulations on all of you who have spent time thinking about ways to make life better for a lot of people — you are making a difference in the world.

Most notable in this category is Eyedrivomatic, the eye-controlled electric wheelechair extension project which was selected as the winner of the 2015 Hackaday Prize. Awarded second prize last year was another notable project. OpenBionics designed an open source, easily manufactured, prosthetic hand. Hand Drive, a Best Product finalist from last year, developed a device to operate a wheelchair with a rowing motion. Like we said, the list goes on and on.

But of course our biggest accomplishments lie ahead. The 2016 Hackaday Prize is currently underway and again focusing on building something that matters. The current challenge is Citizen Scientist which focuses on making scientific experimentation, equipment, and knowledge more widely available. But on August 22nd we turn our sights to the topic of Sophi’s UN Panel as the Hackaday Prize takes on Assistive Technologies. Don’t wait until then, make this the summer you change peoples’ lives. Start your design now.

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Premier Farnell Sold to Swiss Firm

According to this article in the Guardian, Premier Farnell, the electronics parts distributor who is also a UK manufacturer of the Raspberry Pi, is going to be sold to Dätwyler. Their share price immediately rose 50%, closing at just under the Swiss firm’s offer price.

Farnell itself had been on a binge, according to Wikipedia anyway, buying up electronics distributorships in Poland, India, and the US. In 2009, they bought Cadsoft, the makers of Eagle CAD software. Now they’re being sold to another distributor.

Bloomberg writes this up as being just more consolidation in an already consolidating market. What any of this will mean for the hacker on the street is anyone’s guess, but we’re putting our money on it amounting to nearly nothing. But still, now’s the time to stock up on your genuine UK-owned, made-in-UK Pis before they become Swiss-owned and made who knows where.