Misc Hacks

4033 Articles

Electrolytic Capacitor Repair

December 24, 2015 by 18 Comments

If you’ve ever worked on old gear, you probably know that electrolytic capacitors are prone to failure. [Dexter] undertook a repair of some four-decade-old capacitors in a power supply. He didn’t replace them. He fixed the actual capacitors.

The reason these units are prone to fail is the flip side of what people like about electrolytics: high capacitance in a small package. In a classic parallel plate capacitor, the capacity goes up as the distance between the plates shrinks. In an electrolytic, one plate is a rolled up spiral. The other plate is conductive fluid. The insulator between (the dielectric) is a very thin layer of oxide that forms on the spiral. Over time, the oxide degrades, but this degradation repairs itself when using the capacitor. If the capacitor isn’t powered up for an extended period, the oxide will degrade beyond the point of self-repair.

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Before Google There Was The Chemical Rubber Company

December 23, 2015 by 40 Comments

Quick. What’s the difference in conductivity between silver and copper? Today, that’s easy to find out. You just ask Google (maybe even out loud if you have a phone handy). But it wasn’t that long ago that you needed another option. Before the Internet age, a big part of being “that guy” (or gal) was knowing where to go to find things. You had to be a master of the library’s reference section, know what might be in an encyclopedia or an almanac.

However if you were a hardcore math, science, or engineering geek you probably had, at least, one edition of CRC handbooks. Today, we usually think of CRC as cyclic redundancy check, but back then it was the Chemical Rubber Company.

The Chemical Rubber Company dates back to 1903 when brothers Arthur, Leo, and Emanuel Friedman were selling rubber lab aprons in Cleveland, Ohio (Arthur, apparently, had been in a similar business from 1900). In 1913, the brothers offered a short (116-page) booklet called the Rubber Handbook free with the purchase of a dozen aprons.

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God On The CB Radio

December 23, 2015 by 37 Comments

Sometimes art pushes boundaries. We’ve covered a lot of tech art that blurs the lines between the craft of engineering and high-concept art theory. Praydio, by [Niklas Roy] and [Kati Hyyppä] leans easy on the tech, but pushes against viewers’ religious sensibilities.

Playing with the idea of talking directly to God, and with the use of altars as a focal point to do so, [Niklas] and [Kati] took the extremely literal route: embedding a CB radio into a dollar-store shrine. The result? If you’re lucky, someone will answer your prayers, although we’re not too hopeful that the intervention will be divine.

The art critic in us would say that this is a radical democratization of religious authority in that anyone who is tuned in can play the role of Jesus. Or maybe we’d say something about the perception of religious significance in the seemingly random events of our everyday life — maybe it’s not just chance that someone is tuning in at the time you’re asking for help?

Honestly, though, we think they’re just having a bit of fun. The video (below the break) shows someone asking Jesus for a coffee, and the artist on the other end laughs and fetches him one. It’s not high-tech, and it’s not even amateur radio the way we usually think of it, but something about the piece made us laugh, and then to think for a bit. Even if this art isn’t your style, check out [Niklas’] website — he’s got tons of fun projects written up, a few of which we’ve covered here before.

The Scientific Implausibility Of Starkiller Base

December 22, 2015 by 112 Comments

This post contains spoilers for Star Wars: The Force Awakens. These spoilers won’t affect you if you haven’t seen the movie; they’re equivalent to saying, “in A New Hope there’s a moon sized battle station with a superlaser” and “someone gets a hand amputated with a lightsaber in a Star Wars movie”

A lot has happened in the Star Wars universe since the battle of Endor. The Empire is in ruins, and Yavin 5 and the forest moon of Endor both have new planetary ring systems. The Rebellion has given way to a new Galactic Republic, but there is a spectre of evil looming in the unknown areas of the galaxy: the First Order, a malevolent force that has built a planet-sized superweapon capable of destroying entire planetary systems from across the galaxy. The Starkiller gets its energy from harvesting entire suns, moving from one solar system to another to feed this massive weapon of terror.

We’ve had nearly forty years to argue the plausibility of the Death Star, lightsabers, parsecs as a unit of time, and hyperdrives. It’s time to pass the hallowed tradition of arguing over fictional spacecraft to a new generation. Starkiller Base is a cool idea, but does the science behind it hold up? No. It’s completely implausible. It makes for a great story, but it’s completely implausible.

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Muscle Wire Pen Dances To Duke Nukem

December 22, 2015 by 2 Comments

[serdef] is clearly just having a little bit of fun here. One never needs a whiteboard pen that’s syncronized by MIDI to dance along with the theme from Duke Nukem.

But if you had all of the parts on hand (a highly liquid MIDI-driven relay board that connects straight up to a soundcard, some muscle wire, tape, and a whiteboard pen, naturally) we’re pretty sure that you would. You can watch the dancing pen in a video below the break.

The project is really about documenting the properties of [serdef]’s muscle wire, and he found that it doesn’t really contract enough with a short piece to get the desired effect. So he added more wire. We’ve always meant to get around to playing with muscle wire, and we were surprised by how quickly it reacted to changing the voltage in [serdef]’s second video.

Now the dancing pen isn’t the most sophisticated muscle wire project we’ve ever seen. And that award also doesn’t go to this Nitinol-powered inchworm. Did you know that there’s muscle wire inside Microsoft’s Surface?

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Netflix And Chill – And Socks?

December 19, 2015 by 18 Comments

Waking up to spoilers in the last episode after falling asleep during the first episode of a Netflix binge-watching session ranks right up there on the list of first-world problems. Luckily there’s a solution in the form of a pair of Netflix enabled socks, which looks like a pretty neat wearable IoT project.

To be sure, calling these socks Netflix enabled is a bit of a stretch. Aside from the sock designs, which are based on popular Netflix original series, there’s nothing about the electronics that’s specific to the popular streaming service. These socks, with their Arduino Pro Trinket and accelerometer, detect when you stop moving and send an IR signal to do your bidding – pause the movie, kill the TV, or whatever. The electronic side of the build is pretty approachable – it’s just a couple of modules soldered together. The fiber arts side of the project might be a little outside the wheelhouse of the typical hardware hacker, but you can either team up with someone who knits – an experienced knitter, as socks are not a beginner’s pattern – or just slip the felt-clad hardware into your favorite comfy socks. We’d be a bit concerned about ESD protection for the hardware in the wooly environment, though.

“Netflix and chill” is the current version of last century’s “Watching the submarine races,” and as such the need for special socks or a custom Netflix switch for the occasion is a bit puzzling. Still, the underlying wearables idea is pretty good, with plenty of possibilities for expansion and repurposing.

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Gutted USB Power Packs Run Your TV

December 17, 2015 by 30 Comments

With a computer in every pocket, being tethered to large mains-powered appliances is a bit passe. No longer must you be trapped before the boob tube when you can easily watch YouTube on your phone. But you might be jonesing for the big screen experience in the middle of a power outage, in which case learning to build a simple battery bank built from cheap cell-phone power packs might be a good life skill to practice.

Looking more for proof of concept than long-term off-grid usability from his battery bank, [Stephen] cobbled together a quick battery bank from 18650 lithium ion batteries and a small 300W inverter. All the hardware was had on the cheap from an outfit called Cd-r King, a Phillipines-based discount gadgetorium we’d like to see in the states. He got a handful of USB power packs and harvested the single 18650 battery from each, whipped up a quick battery holder from 1/2″ PVC pipe and some bolts to connect the inverter. With four batteries in series he was able to run a flat-screen TV with ease, as well as a large floor fan – say, is that a Mooltipass on [Stephen]’s shelf in the background? And what’s nice about the gutted USB power packs is that they can still be used to recharge the batteries.

As [Stephen] admits, this is a simple project and there’s plenty of room to experiment. More batteries in parallel for longer run times is an obvious first step. He might get some ideas from this laptop battery bank project, or even step up to Tesla Li-ion battery hacking – although we doubt Cd-r King will be of much help with the latter.

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