Author: Elliot Williams

1450 Articles

Reverse Engineering Super Animal Cards

December 11, 2014 by 15 Comments

If you don’t have a niece or nephew we encourage you to get one because they provide a great excuse to take apart kids’ toys.

[Sam] had just bought some animal-themed trading cards. These particular cards accompany a card-reader that uses barcodes to play some audio specific to each animal when swiped. So [Sam] convinces her niece that they should draw their own bar codes. Of course it’s not that easy: the barcodes end up having even and odd parity bits tacked on to verify a valid read. But after some solid reasoning plus trial-and-error, [Sam] convinces her niece that the world runs on science rather than magic.

But it can’t end there; [Sam] wants to hear all the animals. Printing out a bunch of cards is tedious, so [Sam] opens up the card reader and programs and Arduino to press a button and blink an IR LED to simulate a card swipe. (Kudos!) Now she can easily go through all 1023 possible values for the animal cards and play all the audio tracks, and her niece gets to hear more animal sounds than any child could desire.

Along the way, [Sam] found some interesting non-animal sounds that she thinks are Easter eggs but we would wager are for future use in a contest or promotional drawing or something similar. Either way, its great fun to get to listen in on more than you’re supposed to. And what better way to educate the next generation of little hackers than by spending some quality time together spoofing bar codes with pen and paper?

Popular Electronics Magazine Archive Online

December 3, 2014 by 43 Comments

They began publishing Popular Electronics magazine in 1954, and it soon became one of the best-selling DIY electronics magazines. And now you can relive those bygone days of yore by browsing through this archive of PDFs of all back issues from 1954 to 1982.

Reading back through the magazine’s history gives you a good feel for the technological state of the art, at least as far as the DIYer is concerned. In the 1950s and 1960s (and onwards) radio is a big deal. By the 1970s, hi-fi equipment is hot and you get an inkling for the dawn of the digital computer age. Indeed, the archive ends in 1982 when the magazine changed its name to Computers and Electronics magazine.

It’s fun to see how much has changed, but there’s a bunch of useful material in there as well. In particular, each issue has a couple ultra-low-parts-count circuit designs that could certainly find a place in a modern project. For example, a “Touch-Controlled Solid State Switch” in July 1982 (PDF), using a hex inverter chip (CD4049) and a small handful of passive components.

But it’s the historical content that we find most interesting. For instance there is a nice article on the state of the art in computer memory (“The Electronic Mind — How it Remembers”) in August 1956 (PDF).

Have a good time digging through the archives, and if you find something you really like, let us know in the comments.

Kentucky-Fried Induction Furnace

December 2, 2014 by 34 Comments

[John] and [Matthew] built an induction-heater based furnace and used it to make tasty molten aluminum cupcakes in the kitchen. Why induction heating? Because it’s energy efficient and doesn’t make smoke like a fuel-based furnace. Why melt aluminum in the kitchen? We’re guessing they did it just because they could. And of course a video, below the break, documents their first pour.

Now don’t be mislead by the partly low-tech approach being taken here. Despite being cast in a large KFC bucket, the mini-foundry is well put together, and the writeup of exactly how it was built is appreciated. The DIY induction heater is also serious business, and it’s being monitored for temperature and airflow across the case’s heatsinks. This is a darn good thing, because the combination of high voltage and high heat demands a bit of respect.

Anyway, we spent quite a while digging through [John]’s website. There’s a lot of good information to be had if you’re interested in induction heaters. Nonetheless, we’ll be doing our metal casting in the back yard.

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The Halfbug

November 28, 2014 by 4 Comments

[Alex] posted up build details of his robot, Halfbot, on Tinkerlog. We’ve been big fans of his work ever since his Synchronizing Fireflies Instructable way back in the day. [Alex’s] work usually combines an unconventional idea with minimalistic design and precise execution, and Halfbot is no exception.

You’ll have to watch the video (embedded below the break) to fully appreciate the way it moves. The two big front legs alternate with the small front pads to make an always-stable tripod with the caster wheel at the back. It lifts itself up, moves a bit forward, and then rests itself down on the pads again while the legs get in position for the next step. It’s not going to win any speed tournaments, but it’s a great-looking gait.

The head unit also has two degrees of freedom, allowing it to scan around with its ultrasonic rangefinder unit, and adding a bit more personality to the whole affair.

[Alex] mentions that he’d recently gotten a lathe and then a CNC mill. So it’s no surprise that he made all the parts from scratch just to give the machines a workout. We think he did a great job with the overall aesthetics, and in particular the battery pack.

We’re excited to see how [Alex] adds new behaviors as he develops the firmware. No pressure!

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Darth Vader Magic 8 Ball

November 27, 2014 by 4 Comments

Imagine that your wife likes Darth Vader and wants help making important life choices. (Who doesn’t?) [bithead942] solves both problems in one project by gutting a Lego clock and making a talking animatronic Darth Vader 8-Ball-style oracle. Now his wife can simply press Darth’s head and her decision-making is handled by the Dark Side of the Force.

You can see the result in the video below the break.

The internals consist mainly of an Arduino Nano, a WTV020SD WAV playback chip, and some swanky servos. [bithead942] took a Dremel to the existing clock interior and found a way to make it all fit. The cloak helped, and the speaker was a good fit for the previous clock’s display.

Then he used IMDB and combed through the Star Wars movies to find Darth Vader quotes that kinda sound like the 8-Ball’s answers. As [bithead942] mentions Darth Vader doesn’t really dwell much on the positive, so finding instances where he says “yes” was hard work. This is in contrast to the original 8 Ball which has a brighter outlook than a cheerleader on Prozac, but there’s a reason they call it the Dark Side.

We really like the way the waist and arm servos work together to bring Darth to life. The added oak base with pull-out instruction card not only makes Darth look fancy, but prevents him from falling over when he leans forward to talk. All in all, a really nice build and well written-up with difficulties and their solutions.

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Chicken-powered Pendulum

November 24, 2014 by 17 Comments

Every once in a while we get sent a link that’s so cute that we just have to post it. For instance: this video from [Ludic Science]. It’s a wind-up chicken toy that kicks a pendulum back and forth. No more, no less.

But before you start screaming “NOT A HACK!” in the comments below, think for a second about what’s going on here. The bird has a spring inside, and a toothed wheel that is jammed and released by the movement of the bird’s foot (an escapement mechanism). This makes the whole apparatus very similar to a real pendulum clock.

Heck, the chick toy itself is pretty cool. It’s nose-heavy, so that under normal conditions it would tip forward. But when it’s wound up, tipping forward triggers the escapement and makes it hop, tipping it backward in the process and resetting the trigger. The top-heavy chicken is an inverted pendulum!

And have a look, if you will indulge, at the very nice low-tech way he creates the pivot: a bent piece of wire, run through a short aluminum tube, held in place by a couple of beads. Surely other pivots are lower-friction, but the advantage of using a rod and sleeve like this is that the pendulum motion is constrained to a plane so that it never misses the chicken’s feet.

Our only regret is that he misses (by that much) the obvious reference to a “naked chick” at the end of the video.

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Laser-cut Album Released

November 19, 2014 by 15 Comments

In some alternate universe, where laser cutters and phonographs are more common than MP3 players, it makes a ton of sense to release laser-cutter files for your band’s new album (Translated). In this universe, it’s wacky and awesome.

The new EP from ASIC, alias [Patric] from Fablab Zürich, is out as PDF before it’s out in other forms of digital download, and the trailer video (embedded below the break) looks fantastic.

The release draws on this Instructable by Amanda Ghassaei to turn the music into PDFs suitable for feeding into a laser cutter, and we think it’s classy that she gets a shout-out on the label’s release page.  Everything else about the album will be released under a Creative Commons license to boot.

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