Transformer Inductive Coupling Simulation Is SFW

October 2, 2014 by Kristina Panos 12 Comments

[James] has a friend who teaches at the local community college. When this friend asked him to build a transformer coupling simulation, he was more than happy to oblige. Fortunately for us, he also made a video that explains what is happening while showing the output on a ‘scope.

For the simulation, [James] built primary and secondary coils using PVC pipe. The primary coil consists of 11 turns of 14AWG stranded wire with 4V ~~running through it~~ applied. The first secondary he demonstrates is similarly built, but has 13 turns. As you’ll see, the first coil induces ~1.5V in the second coil. [James] first couples it with the two windings going the same way, which results in the two 2Mhz waveforms being in phase with each other. When he inserts the secondary the other way, its waveform is out of phase with the primary’s.

His second secondary has the same diameter PVC core, but was wound with ~60 turns of much thinner wire—28AWG bell wire to be exact. This match-up induces 10V on the secondary coil from the 4V he put on the primary. [James]’ demonstration includes a brief Lissajous pattern near the end. If you don’t know enough about those, here’s a good demonstration of the basics coupled with an explanation of the mechanics behind them.

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Invisibility Achieved With A Few Clever Focal Points

October 1, 2014 by James Hobson 53 Comments

Students at the University of Rochester have developed a clever optical system which allows for limited invisibility thanks to a bit of optic ~~sorcery~~ physics.

Almost all invisibility technologies work by taking light and passing it around the object as if it were never there. The problem is, a lot of these methods are very expensive and not very practical — and don’t even work if you change your perspective from a head on view.

[Joseph Choi] figured out you can do the same thing with four standard achromatic lenses with two different focal lengths. The basic concept is each lens causes the light to converge to a tiny point in between itself and the next lens — at which point it begins to diverge again, filling the following lens. This means the cloaked area is effectively doughnut shaped around the tightest focal point — if you block the center point of the lens, it won’t work. But everything around the center point of the lens? Effectively invisible. Take a look at the following setup using lasers to show the various focal points and “invisibility zones”.

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Mining Bitcoins With Pencil And Paper

September 29, 2014 by Brian Benchoff 17 Comments

Right now there are thousands of computers connected to the Internet, dutifully calculating SHA-256 hashes and sending their results to other peers on the Bitcoin network. There’s a tremendous amount of computing power in this network, but [Ken] is doing it with a pencil and paper. Doing the math by hand isn’t exactly hard, but it does take an extraordinary amount of time; [Ken] can calculate about two-thirds of a hash per day.

The SHA-256 hash function used for Bitcoin isn’t really that hard to work out by hand. The problem, though, is that it takes a 64 byte value, sends it through an algorithm, and repeats that sixty-four times. There are a few 32-bit additions, but the rest of the work is just choosing the majority value in a set of three bits, rotating bits, and performing a mod 2.

Completing one round of a SHA-256 hash took [Ken] sixteen minutes and forty-five seconds. There are sixty-four steps in calculating the hash, this means a single hash would take about 18 hours to complete. Since Bitcoin uses a double SHA-256 algorithm, doing the calculations on a complete bitcoin block and submitting them to the network manually would take the better part of two days. If you’re only doing this as your daily 9-5, this is an entire weeks worth of work.

Just for fun, [Ken] tried to figure out how energy-efficient the bitcoin mining rig stored in his skull is. He can’t live on electricity, but donuts are a cheap source of calories, at about $0.23 per 200 kcalories. Assuming a metabolic rate of 1500 kcal/day, this means his energy cost is about 67 quadrillion times that of an ASIC miner.

Video below.

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‘Duinos And VR Environments

September 27, 2014 by Brian Benchoff 5 Comments

At the Atmel booth at Maker Faire, they were showing off a few very cool bits and baubles. We’ve got a post on the WiFi shield in the works, but the most impressive person at the booth was [Quin]. He has a company, he’s already shipping products, and he has a few projects already in the works. What were you doing at 13?

[Quin]’s Qduino Mini is your basic Arduino compatible board with a LiPo charging circuit. There’s also a ‘fuel gauge’ of sorts for the battery. The project will be hitting Kickstarter sometime next month, and we’ll probably put that up in a links post.

Oh, [Quin] was also rocking some awesome kicks at the Faire. Atmel, I’m trying to give you money for these shoes, but you’re not taking it.

[Sophie] had a really cool installation at the faire, and notably something that was first featured on hackaday.io. Basically, it’s a virtually reality Segway, built with an Oculus, Leap Motion, a Wobbleboard, an Android that allows you to cruise on everyone’s favorite barely-cool balancing scooter through a virtual landscape.

This project was a collaboration between [Sophie], [Takafumi Ide], [Adelle Lin], and [Martha Hipley]. The virtual landscape was built in Unity, displayed on the Oculus, controlled with an accelerometer on a phone, and has input with a Leap Motion. There are destructible and interactable things in the environment that can be pushed around with the Leap Motion, and with the helmet-mounted fans, you can feel the wind in your hair as you cruise over the landscape on your hovering Segway-like vehicle. This is really one of the best VR projects we’ve ever seen.

Starting To Wrap Up Maker Faire

September 26, 2014 by Brian Benchoff 3 Comments

It’s almost a week since the NYC Maker Faire, and it’s about time for us to start wrapping up all the posts we’re doing on everything we’ve seen.

[Chris Mitchell], hackaday favorite from Cemetech did what he always does at Maker Faire: brought some stuff he’s doing with TI graphing calculators.

The TI-84 with GPS made a showing, as did the graphing calculator IRC client. By far the coolest looking calculator was the wooden casemod. It’s a TI-82 put into a (what feels and looks like) a maple enclosure. The buttons are painted on, and despite stuffing consumer electronics into a handmade case, it’s still reasonable portable.

There were more Hackaday fans at the faire, but I’m not sure if anyone can beat the guys from Protopalette. Wait. One guy could. Find me in public sometime and I’ll tell you about that.

The Protopalette is a board with a bunch of lights, buttons, switches, sensors, knobs, servos, and buzzers for electronics prototyping. Think of it as a stylized version of the old ‘parts and springs and wire’ radio shack beginner electronic kits.

Some of the members of the hackerspace with the craziest group narrative, LVL1 in Louisville, made it to the faire. They’re working with GE to create a ‘maker module’ for appliances. It’s called Green Bean, and GE is actually building support for this into some of their fridges, washers, stoves and dishwashers.

There are a few modules already, like a scale that will send out a message when you’re out of milk. It’s an interesting system, and there are already a lot of appliances that support the system.

Pics below.

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Choreographed Iron Dust Dances To The Beat

September 23, 2014 by Adam Fabio 6 Comments

Up on the second level of World Maker Faire’s main hall, one could hear Technotronic’s hit “Pump up the Jam” playing again and again. We were expecting breakdancing robots, but upon investigating, what we found was something even better. [David Durlach] was showing off his Choreographed Iron Dust, a 9 x 9 grid of magnets covered in iron filings. The filings swayed and danced to the beat of the music, at times appearing more like ferrofluid than a dry material. Two LED lights shined on the filings from an oblique angle. This added even more drama to the effect as the light played on the dancing spikes and ridges.

While chatting with [David] he told us that this wasn’t a new hack. Choreographed Iron Dust made its debut at the Boston Museum of Science back in 1989. Suddenly the 80’s music made more sense! The dust’s basic control system hasn’t changed very much since the 1980’s. The magnets are actually a stack of permanent and electromagnets. The permanent magnet provides enough force to hold the filings in place. The electromagnets are switched on to make the filings actually dance.

Since it was designed in 1989, there were no Arduinos available. This project is powered by the most hacker friendly interface of the era: the PC’s parallel port. As one might imagine, [David] has been having a hard time finding PC’s equipped with parallel ports these last few years.

[David] wasn’t just showing off iron dust. Having spent so much time painstakingly animating the iron filings for various customers, he knew there had to be a better way. He’s come up with ChoreoV, a system which can take recorded video, live performances, or even capture a section of a user’s screen. The captured data can then be translated directly into light or motion on an art piece.

The Abovemarine

September 17, 2014 by Brian Benchoff 48 Comments

Over the course of a few weeks, [Adam] trained his betta fish, [Jose], to jump out of the water to snatch food off his finger. An impressive display for a fish, but being able to train his small aquatic friend got [Adam] thinking. What’s stopping [Jose] from interacting his environment even more? The abovemarine was born.

The abovemarine is a robotic platform specifically built for [Jose]’s aquarium. Below, three omni wheels drive the entire aquarium in any direction. A computer running OpenCV, a webcam, and a few motors directs the abovemarine in whatever direction [Jose] wants to go. Yes, it’s a vehicle for a fish, and that’s awesome.

[Adam] put a lot of work into the creation of the abovemarine, and was eventually able to teach [Jose] how to control his new home. In the videos below, you can see [Jose] roaming the studio and rolling towards the prospect of food.

Because [Jose] is a Siamese fighting fish and extremely territorial when he sees other males of his species, this brings up the idea of a version of Battlebots with several abovemarines. They’re in different tanks, so we don’t know what PETA would think of that, but we do expect it to show up in the Hackaday tip line eventually.

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