[Mechanicus] has made a supercapacitor with a claimed 55 Farads per gram of active material. And he’s made it using dryer lint and dog hair. And he’s done it in 24 hours. That’s the short story. The longer story is an epic journey of self-discovery and dog ownership, and involves a cabin in the Wyoming backwoods.
So how did he do it?
He started with a home-made crucible that you maybe wouldn’t want to carry around in public as it bears more than a passing resemblance to a pipe bomb. Into that he packed his dog hair and lint, along with a generous helping of ammonia. An hour or two in a woodstove glowing red, and he’d made a rod of mostly carbon with the required high surface area. He sawed off a carbon slice, bathed it in lithium sulphate and potassium iodide electrolyte, and with the addition of a couple of pieces of stainless steel he had a supercapacitor.
Full details of his build can be found on the hackaday.io pages linked above, but there is also a handy YouTube video below the break.
Continue reading “Lint And Dog Hair Supercapacitor”
If you understand technology, there were a lot of things hard to explain on Star Trek. Transporters, doors that were smart enough to open unless you hit them during a fight, and the universal translator all defy easy explanation. But one of the hardest things to explain were Mr. Spock’s sensors. From the ship or with a tricorder, Spock could sense at a distance just about anything from chemical compositions, to energy, and even the presence of life (which, today, at least, is difficult to determine even what that means).
Remote sensing would have a very distinct use in today’s world: finding terrorist bombs earlier. A recent article published on New Scientist by [Debora MacKenzie] points out that stopping attacks like the recent one in Brussels is difficult without increasing congestion. For example, putting checkpoints at doors instead of inside transit stations is common in Asia, but causes lines and delays.
The United States has used ion mobility spectrometry (IMS) to detect explosive traces on swabs (using machines like the one on the left). However in the early 2000’s they experimented with a version of the device that used puffs of air to determine if people had explosives while they passed by the machine. By 2010, officials decided the machines broke down too often and stopped using them.
Remote Sensing in Practice
According to an expert at Rand Corporation, remote sensing is likely to employ imaging or sniffers. However, imaging solutions are easy to fool since a bomb can take the shape of an ordinary object. Sniffers, including biological sniffers (known as dogs), are harder to fool. The problem is that deploying thousands of dogs to cover the world’s airports is difficult.
Continue reading “Remote Sensing Bombs Could Stem Terrorism”
Fuel cells are like batteries, sort of. Both use chemical reactions to produce electricity. The difference is that when a battery exhausts its reactants, it goes dead. In some cases, you can recharge it, but you typically get less energy back with each recharge. A fuel cell, on the other hand, will make electricity as long as you keep supplying fuel. What kind of fuel? Depends on the cell, but most often it is hydrogen or methanol.
Researchers at the University of Bath, Queen Mary University of London, and the Bristol Robotics Laboratory want to use a different fuel: urine. According to the researchers, that’s one resource we will never deplete. The fuel cell is a type of microbial fuel cell which is nothing new. The breakthrough is that the new cell is relatively inexpensive, using carbon cloth and titanium wire. Titanium isn’t usually something you think of as cheap, until you realize that conventional cells usually use platinum.
Continue reading “They Put the “P” in Power”
We all know that you can stick copper and zinc in an acid and make a battery. And the classic demonstration of this is with a lemon. YouTuber [NorthSurvival] takes this to an extreme — starting a fire by shorting his lemon battery across some steel wool. (Video embedded below.)
Now calling this a “survival tip” is pushing it. A lot. When’s the last time you went camping with a bunch of zinc and copper nails, much less a supply of fresh lemons? It might be easier to put some matches in a waterproof canister, or just bring a lighter. But when the zombie apocalypse comes, and all the lighters are used up, the man with a lemon tree will be a millionaire.
Seriously, though, this demo made us question a few assumptions. First, when people do the potato- or lemon-battery experiment, they often use multiple lemons. Why? Hooking the pins up like [NorthSurvival] did in series seems like a no-brainer after the fact.
And the lemon seems to be putting out a fair amount of juice (Amperes, that is). We’ve got to wonder — what is the short-circuit current of a lemon battery? And why haven’t we seen specs anywhere? What kind of “science education” experiment is this anyway, without measurements?
Continue reading “Lighting Fires with Lemons”
The Farnsworth Fusor is a fascinating device, a reactor that fuses hydrogen into helium by creating a plasma under a very high voltage. Although it isn’t a practical way to generate energy, it is a fascinating way to see nuclear fusion. An increasing number of home experimenters are starting to build their own fusors, and [Erik] decided he wanted to be among them. He’s put together a great build log of his progress, starting with a propane tank he bought off craigslist. He added a window, a vacuum pump and a 40KV power supply. Once he added some deuterium (electrolyzed from heavy water he bought from United Nuclear) it was ready to go. After a couple of failed runs, he got the characteristic plasma glow that shows that the reactor is working. The central globe is the plasma, while the light on the left side is a beam of electrons freed by the fusion process. So far, [Erik] has not detected the high-energy neutrons that would show that fusion is underway, but he is close.
Needless to say, this is not a casual build. [Erik] is using a 40KV power supply that would kill you in a heartbeat if your body happened to be the easiest pathway to ground,
especially as the power supply is generating pulls over 9 amps to create the fusion reaction. [Erik] joins a select group of amateur fusor builders called the Plasma Club. It isn’t the first Farnsworth Fusor that we have covered, but it is one of the most impressive.
What’s worse than coming in from the workbench for a sandwich only to discover that the bread has molded? That red bread mold–Neurospora crassa–can transform manganese into a mineral composite that may improve rechargeable batteries, according to a recent paper in Current Biology.
Researchers used the carbonized fungal biomass-mineral composite in both lithium ion cells and supercapacitors. The same team earlier showed how fungi could stabilize toxic lead and uranium. Mold, of course, is a type of fungus that grows in multi-cellular filaments. Apparently, the fungal filaments that form are ideal for electrochemical use of manganese oxide. Early tests showed batteries using the new material had excellent stability and exceeded 90% capacity after 200 discharge cycles.
The team plans to continue the use of fungus in various metallurgical contexts, including recovering scarce metal elements. This is probably good news for [Kyle]. This is quite an organic contrast to the usual news about graphene batteries.
Image: Qianwei Li and Geoffrey Michael Gadd
Metalwork of any kind is fascinating stuff to watch. When the metalwork in question is in service of the clockmaker’s art, the ballgame changes completely. Tiny screws and precision gears are created with benchtop lathes and milling machines, and techniques for treating metals border on alchemy – like heat-bluing of steel clock hands for a custom-built clock.
If you have even a passing interest in metalwork and haven’t followed [Clickspring]’s YouTube channel, you don’t know what you’re missing. [Chris] has been documenting a museum-quality open-body clock build, and the amount of metalworking skill on display is amazing. In his latest video, he covers how he heat-blues steel to achieve a wonderful contrast to the brass and steel workings. The process is simple in principle but difficult in practice – as steel is heated, a thin layer of oxides forms on the surface, enough to differentially refract the light and cause a color change. The higher the heat, the thicker the layer, and the bluer the color. [Chris] uses a custom-built tray filled with brass shavings to even out the heat of a propane torch, but even then it took several tries to get the color just right. As a bonus, [Chris] gives us a primer on heat-treating the steel hands – the boric acid and methylated spirits bath, propane torch flame job and oil bath quenching all seems like something out of a wizard’s workshop.
We’ve covered [Chris]’ build before, and we encourage everyone to tune in and watch what it means to be a craftsman. We only hope that when he finally finishes this clock he starts another project right away.
Continue reading “Metal Magic: Heat Bluing Steel Clock Hands”