Glowing Eyes For Regular Guys

December 18, 2018 by 47 Comments

Cosplayers continually push the boundary of what’s possible in live costuming, often taking effects from the silver screen and creating them in real life. [KyleofAsgard] is no exception, bringing Thor’s glowing eyes to life in this impressive build.

The helmet is a 3D printed piece from Thingiverse, painted and distressed by hand.

The build relies on special contact lenses, which [Kyle] suggests are best sourced by searching for “electric blue contact lenses”. These glow in the presence of UV light, which here is provided by a strip of UV LEDs embedded into Thor’s helmet from the recent Marvel movies.

The concept is simple, but the attention to detail is what makes this project a winner. Not content with an earlier build that was a tangle of wires and uncomfortable to use, [KyleofAsgard] made some smart upgrades. The battery for the LEDs and all circuitry is built into the helmet, making it easy to take on and off on those long convention days. For a more impressive effect, a relay is used to turn the LEDs on by remote control with a 433MHz module. This allows [Kyle] or an assistant to trigger the effect covertly, adding plenty of drama when the eyes suddenly begin to shine. It’s all done with off-the-shelf parts that even a novice could put together.

Giving credit where it’s due, [Kyle] notes that his work was inspired by that of Instagram cosplayer [missxboof], who executed a similar concept earlier this year. It’s great to see the cosplay community coming together and sharing tips and techniques online. Of course, if your tastes are more Metroid than Marvel, you might prefer this arm cannon build. Video after the break.

[Thanks to NZSmartie for the tip!]

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Old Wattmeter Uses Magnetics To Do The Math

December 18, 2018 by 19 Comments

Measuring power transfer through a circuit seems a simple task. Measure the current and voltage, do a little math courtesy of [Joule] and [Ohm], and you’ve got your answer. But what if you want to design an instrument that does the math automatically? And what if you had to do this strictly electromechanically?

That’s the question [Shahriar] tackles in his teardown of an old lab-grade wattmeter. The video is somewhat of a departure for him, honestly; we’re used to seeing instruments come across his bench that would punch a seven-figure hole in one’s wallet if acquired new. These wattmeters are from Weston Instruments and are beautiful examples of sturdy, mid-century industrial design, and seem to have been in service until at least 2013. The heavy bakelite cases and sturdy binding posts for current and voltage inputs make it seem like the meters could laugh off a tumble to the floor.

But as [Shahriar] discovers upon teardown of a sacrificial meter, the electromechanical movement behind the instrument is quite delicate. The wattmeter uses a moving coil meter much like any other panel meter, but replaces the permanent magnet stator with a pair of coils. The voltage binding posts are connected to the fine wire of the moving coil through a series resistance, while the current is passed through the heavier windings of the stator coils. The two magnetic fields act together, multiplying the voltage by the current, and deflect a needle against a spring preload to indicate the power. It’s quite clever, and the inner workings are a joy to behold.

We just love looking inside old electronics, and moving coil meters especially. They’re great gadgets, and fun to repurpose, too.

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Hackaday Podcast: 2018 Year In Review

December 18, 2018 by 19 Comments

Did you read all 3000+ articles published on Hackaday this year? We did. And to help catch you up, we preset the Hackaday 2018 Year in Review podcast!

Join us for the podcast, available on all major podcasting platforms, as Editors Mike Szczys and Elliot Williams attempt the impossible task of distilling the entire year into a one hour discussion. We’ve included every story mentioned in the podcast, and a few more, in the show notes here. But since we can’t possibly mention every awesome hack, we encourage you to share your favorites, and pat the writers on the back, by leaving a comment below.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (60 MB or so.)

Where to Follow Hackaday Podcast

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Thread Carefully: An Introduction To Concurrent Python

December 18, 2018 by 7 Comments

The ability to execute code in parallel is crucial in a wide variety of scenarios. Concurrent programming is a key asset for web servers, producer/consumer models, batch number-crunching and pretty much any time an application is bottlenecked by a resource.

It’s sadly the case that writing quality concurrent code can be a real headache, but this article aims to demonstrate how easy it is to get started writing threaded programs in Python. Due to the large number of modules available in the standard library which are there to help out with this kind of thing, it’s often the case that simple concurrent tasks are surprisingly quick to implement.

We’ll walk through the difference between threads and processes in a Python context, before reviewing some of the different approaches you can take and what they’re best suited for.

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Can You 3D-Print A Stator For A Brushless DC Motor?

December 18, 2018 by 33 Comments

Betteridge’s Law holds that any headline that ends in a question mark can be answered with a “No.” We’re not sure that [Mr. Betteridge] was exactly correct, though, since 3D-printed stators can work successfully for BLDC motors, for certain values of success.

It’s not that [GreatScott!] isn’t aware that 3D-printed motors are a thing; after all, the video below mentions the giant Halbach array motor we featured some time ago. But part of advancing the state of the art is to replicate someone else’s results, so that’s essentially what [Scott!] attempted to do here. It also builds on his recent experiments with rewinding commercial BLDCs to turn them into generators. His first step is to recreate the stator of his motor as a printable part. It’s easy enough to recreate the stator’s shape, and even to print it using Proto-pasta iron-infused PLA filament. But that doesn’t come close to replicating the magnetic properties of a proper stator laminated from stamped iron pieces. Motors using the printed stators worked, but they were very low torque, refusing to turn with even minimal loading. There were thermal issues, too, which might have been mitigated by a fan.

So not a stunning success, but still an interesting experiment. And seeing the layers in the printed stators gives us an idea: perhaps a dual-extruder printer could alternate between plain PLA and the magnetic stuff, in an attempt to replicate the laminations of a standard stator. This might help limit eddy currents and manage heating a bit better. Continue reading “Can You 3D-Print A Stator For A Brushless DC Motor?” →

GPS III Launching Today But You Can’t Use It Until 2022

December 18, 2018 by 49 Comments

Imagine if you bought a new car but they keys were not going to be shipped to you until a few years later. That’s analogous to the situation the U.S. Air Force finds itself in. The first GPS III satellite is finally ready to launch today, December 18, 2018 — a little over 2 years beyond the original schedule. However, most of the unique GPS III features won’t be available until at least 2022, according to a 2017 Government Accounting Office (GAO) report to Congress.

GPS III is a project to launch 32 new satellites that will — for military users — be more difficult to jam. For civilian users, the new GPS satellites will be compatible with other systems, including the EU’s Galileo system. But the big draw? About three times the accuracy of the current system. For civilian use, that means 3 to 10 feet under good conditions as opposed to the current systems’ 10- to 33-foot resolution.

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Does Library Bloat Make Your Smartphone App Look Fat?

December 18, 2018 by 53 Comments

While earlier smartphones seemed to manage well enough with individual applications that only weighed in at a few megabytes, a perusal of the modern smartphone software store uncovers some positively monstrous file sizes. The fact that we’ve become accustomed to mobile applications requiring 100+ MB downloads on what’s often a metered Internet connection in only a few short years is pretty crazy if you stop to think about it.

Seeing reports that the Nest app for iOS tipped the scales at nearly 250 MB, [Alexandre Colucci] decided to investigate. On his blog he not only documents the process of taking the application apart piece by piece to find out just what’s eating up all that space, but lists some potential fixes which could shave a bit off the top. Even if you aren’t planning a spelunking expedition into your pocket supercomputer’s particular variant of the Netflix app, the methodology and tools he uses here are fascinating in their own right and might be something worth adding to your software bag of tricks.

By passing the application’s files through a disk usage visualizer called GrandPerspective, [Alexandre] immediately identified some rather large blocks of content. The bundled Apple Watch version of the app takes up 23 MB, video and audio used to walk the user through the device setup weigh in at 22 MB, and localization files for various languages consumes a surprising 33 MB. But the biggest single contributor to the application’s heft is the assorted libraries and frameworks which total up to an incredible 67 MB.

Of course the question is, how much of it is really necessary? It’s hard to be sure from an outsider’s perspective, but [Alexandre] notes that a few of the libraries used seem to be redundant or obsolete. In some cases this could be the result of old code still lurking in the project, but the four different libraries used for user tracking probably aren’t in there by accident. It also stands to reason that the instructional videos could be offloaded to something like YouTube, so that only users who need to view them have to expend their bandwidth on it.

Getting a little deeper into things, [Alexandre] notes that some of the localization images appear to be redundant. As a specific example, he points to the images of the Nest itself displaying Fahrenheit and Celsius temperatures. While logically this should only be two image files, there are actually eight copies of the Celsius image, each filed away as language-specific. These redundant localization images could easily be stripped out, but with gains measured in only a few hundred kilobytes, it probably wasn’t considered worth the effort during development.

In the end there’s really not as much bloat as we might like to believe. There were some redundant files, maybe a few questionable library inclusions, and the Apple Watch version of the app could surely be separated out. All together, it might get you a savings of 30 – 40%, but still not enough to bring it down under 100 MB.

All signs point to the fact that modern smartphone software development is just a lot more burdensome than us hackers might like. Save for projects looking to put control back into the hand’s of the users, it looks like mobile operating systems aren’t going to be slimming down anytime soon.