Pickle Diodes, Asymmetric Jacobs Ladders, And Other AC Surprises

January 3, 2026 by Tyler August 15 Comments

While we’re 100 years past Edison’s fear, uncertainty, and doubt campaign, the fact of the matter is that DC is a bit easier to wrap one’s head around. It’s just so honest in its directness. AC, though? It can be a little shifty, and that results in some unexpected behaviors, as seen in this video from [The Action Lab].

He starts off with a very relatable observation: have you ever noticed that when you plug in a pickle, only half of it lights up? What’s up with that? Well, it’s related to the asymmetry he sees on his Jacobs ladder that has one side grow hotter than the other. In fact, it goes back to something welders who use DC know about well: the Debye sheath.

The arc of a welder, or a Jacobs ladder, or a pickle lamp is a plasma: ions and free electrons. Whichever electrode has negative is going to repel the plasma’s electrons, resulting in a sheath of positive charge around it. This positively-charged ions in the Debye sheath are going to accelerate into the anode, and voila! Heating. That’s why it matters which way the current goes when you’re welding.

With DC, that makes sense. In AC, well — one side starts as negatively charged, and that’s all it takes. It heats preferentially by creating a temporary Debye sheath. The hotter electrode is going to preferentially give off electrons compared to its colder twin — which amplifies the effect every time it swings back to negative. It seems like there’s no way to get a pure AC waveform across a plasma; there’s a positive feedback loop at whatever electrode starts negative that wants to introduce a DC bias. That’s most dramatically demonstrated with a pickle: it lights up on the preferentially heated side, showing the DC bias. Technically, that makes the infamous electric pickle a diode. We suspect the same thing would happen in a hot dog, which gives us the idea for the tastiest bridge rectifier. Nobody tell OSHA.

[The Action Lab] explains in more detail in his video, and demonstrates with ring-shaped electrode how geometry can introduce its own bias. For those of us who spend most of our time slinging solder in low-voltage DC applications, this sort of thing is fascinating. It might be old hat to others here; if the science of a plain Jacobs ladder no longer excites you, maybe you’d find it more electrifying built into a blade.

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The solar-electric tractor is out standing in its field.

Adding Solar Power To An Electric Tractor

January 2, 2026 by Tyler August 9 Comments

In my country, we have a saying: the sun is a deadly lazer. Well, it’s not so much a folk saying as a meme, and not so much in one country as “the internet”. In any case, [LiamTronix] was feeling those cancer rays this harvest season when running his electric tractor, and realized that– since he’s already charging it with ground-mounted solar panels anyway–if he’s going to build a roof for his ride, he might as well make charge the batteries.

Another bonus is safety: the old Massey-Ferguson at the heart of the electric tractor build didn’t come with any rollover protection from the factory back in the 1960s. Since having however many tons of tractor roll onto you was bad enough before it got a big hefty battery pack, we heartily approve of including a roll cage in this build. Speaking of battery packs, he’s taking this chance to upgrade to a larger LiFePo pack from the LiIon pack he installed when we first featured this conversion in 2024.

Atop the new roll cage, and above the new battery, [Liam] installed four second-hand 225 W solar panels. Since that’s under 1kW even if the panels have not degraded, the tractor isn’t going to be getting much charge as it runs. In the northern winter, [Liam] is only able to pull 80 W from the set. That’s not getting much work done, but who wants a tractor without a cab or heater when it’s below freezing? In the summer it’s a much better story, and [Liam] estimates that the roof-mounted panels should provide all of the energy needed to run the tractor for the couple hours a day he expects to use it.

If you’re wondering how practical all this is, yes, it can farm — we covered [Liam] putting the project through its paces in early 2025.

The big white thing is is the CO2 exhaust bag.

Liquid CO2 For Grid Scale Energy Storage Isn’t Just Hot Air

January 2, 2026 by Tyler August 129 Comments

There’s folk wisdom in just about every culture that teaches about renewable energy — things like “make hay while the sun shines”. But as an industrial culture, we want to make hay 24/7 and not be at the whims of some capricious weather god! Alas, renewable energy puts a crimp in that. Once again, energy supplies are slowly becoming tied to the sun and the wind.

Since “Make compute while the wind blows” doesn’t have a great ring to it, clearly our civilization needs to come up with some grid-scale storage. Over in Sardinia they’re testing an idea that sounds like hot air, but isn’t — because the working gas is CO2.

The principle is simple: when power is available, carbon dioxide is compressed, cooled, and liquefied into pressure vessels as happens at millions of industrial facilities worldwide every day. When power is required, the compressed CO2 can be run through a turbine to generate sweet, sweet electricity. Since venting tonnes of CO2 into the atmosphere is kind of the thing we’re trying to avoid with this whole rigmarole, the greenhouse gas slash working fluid is stored in a giant bag. It sits, waiting for the next charge cycle, like the world’s heaviest and saddest dirigible. In the test project in Sardinia — backed by Google, amongst others — the gas bag holds 2000 tonnes and can produce 20 megawatts of power for up-to 10 hours.

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Building A Steam Loco These Days Is Nothing But Hacks

January 1, 2026 by Tyler August 34 Comments

The Pennsylvania Railroad (PRR)’s T1 class is famous for many reasons: being enormous, being a duplex, possibly having beaten Mallard’s speed record while no one was looking… and being in production in the 21st century. That last fact is down to the redoubtable work by the PRR T1 Steam Locomotive Trust, who continued their efforts to reproduce an example of these remarkable and lamentably unpreserved locomotives in the year 2025.

They say that 2025 was “the year of the frame” because the frame was finally put together. We might say that for the PRR Trust, this was the year of welding. Back when the Baldwin and Altoona works were turning out the originals, the frames for steam locomotives were cast, not welded. There might not be anywhere on Earth to get a 64′ long (19.5 m), 71,000 lbs steel casting made these days. Building it up with welded steel might not be perfectly accurate, but it’s the sort of hack that’s needed to keep the project moving.

The cylinders, too, would have been bored-out castings back the day. Getting the four (it’s a duplex, remember) assemblies cast as one piece didn’t prove practical, so T1 #5550 will have welded cylinders as well. Given modern welding, we expect no problem with holding steam pressure. The parts are mostly machined and will be welded-together next year.

The giant wheels of the locomotive have been cast, but need to be machined. It’s not impossible to believe that locomotive #5550 will be on its frame, on its wheels, in 2026. The boiler is already done and the injectors to get water into it have been reinvented, which can perhaps be considered another hack.

Right now, if donations continue to trickle in at the current rate– and prices don’t rise any faster than they have been– the Trust hopes to have the locomotive steaming in 2030. She’s now 59.8% complete. That’s up from 40% when we last checked in, back in 2022, which is great progress considering this is a volunteer-driven, crowd-funded effort.

If you don’t have the skills or geographical location to volunteer with this build, but we’ve piqued your love of steam, perhaps you could 3D print an engine to scratch the itch.

Continue reading “Building A Steam Loco These Days Is Nothing But Hacks” →

A giant pokeball is the best place to hide this holiday season.

Our New Years Wish Is To Hide In A Giant Pokéball

January 1, 2026 by Tyler August 7 Comments

Between the news, the world situation, and the inevitable family stresses that come this time of year, well — one could be excused for feeling a certain amount of envy for those adorable pocket monsters who spend their time hidden away in red-and-white orbs. [carlos3dprint] evidently did, but he didn’t just dream of cozy concave solitude: he made it happen, with 3D printing and way too much post-processing.

Arguably 3D printing is not the ideal technique for such a large build, and even [carlos], despite the 3dprint in his handle, recognized this: the base frame of the sphere is CNC-routed plywood. He tried to use Styrofoam to make a skin, but evidently he’d lost access to the large CNC cutter he’d borrowed for the plywood frame at that point, as he was trying to do the cuts by hand. It still seems like it wouldn’t have be any worse than the little printed blocks from four different printers he eventually hot-stapled into a shell.

We only say that because based on his description of how much resin and filler went into creating a smooth outer surface on his Pokéball, the raw surface of the prints must have been pretty bad before fiberglass was applied. Still, it’s hard to argue with results, and the results are smooth, shiny and beautiful after all the sanding and painting. Could another technique have been easier? Maybe, but we hack with what we have, and [carlos] had 3D printers and knows how to make the best of them.

The interior of the ball is just large enough for a cozy little gaming nook, and no guesses what [carlos] is playing inside. The Instructable linked above doesn’t have many interior photos, though, so you’ll have to check the video (embedded below) for the interior fitting out, or jump to the tour at about the 15 minute mark.

Given ongoing concerns about VOCs from 3D printers, we kind of hope the Bulbsaur-themed printer he’s got in there is decorative, but it’s sure a nice homage to the construction method. Other pokeballs featured on Hackaday have been much smaller, but we’ve always had a soft spot for scaled-up projects.

Continue reading “Our New Years Wish Is To Hide In A Giant Pokéball” →

Bringing A Yagi Antenna To 915MHz LoRa

December 31, 2025 by Tyler August 34 Comments

If you’re a regular reader of Hackaday, you may have noticed a certain fondness for Meshtastic devices, and the LoRa protocol more generally. LoRa is a great, low-power radio communications standards, but sometimes the antennas you get with the modules can leave you wanting more. That’s why [Chris Prioli] at the Gloucester County Amateur Radio Club in the great state of New Jersey have got a Yagi antenna for North America’s 915 MHz LoRa band.

Right out the gate, their article links to one of ours, where [tastes_the_code] builds a Yagi antenna for the European 868 MHz LoRa. Like [tastes_the_code], the radio club found [Chris]’s antenna gives much better reception than what came with the LoRa module. Looking out their window, instead of two Metastatic nodes with a stock antenna, one club member is now connecting to two hundred.

A simulation of the radiation pattern. Looks like a Yagi, alright.

Now, the Yagi is directional, so you only get that boost pointed down the axis of the antenna, but at least in simulation they estimate a 7.7 dB front-to-back gain vs under 3 dB for an omnidirectional antenna. Not bad, for a simple 3D print and some stiff wire!

If you don’t want to re-invent the wheel again, check out the GCARC’s GitHub for files if you’re in North America. If you’re in Europe, check out [taste_the_code]’s build from last year. Of course whatever band you’re operating in, Yagi isn’t your only roll-your-own option for a LoRa antenna.

Thanks to [Jon Pearce WB2MNF] for the tip!

All Projections Suck, So Play Risk On A Globe Instead

December 30, 2025 by Tyler August 11 Comments

The worst thing about the getting people together is when everyone starts fighting over their favourite map projection– maybe you like the Watterman Butterfly, but your cousin really digs Gall-Peters, and that one Uncle who insists on defending Mercator after a couple of beers. Over on Instructables [madkins9] has an answer to that problem that will still let you play a rousing game of Risk– which will surely not drag on into the night and cause further drama– skip the projection, and put the game on a globe.

The pieces are from a 1960s version. The abstract tokens have a certain charm the modern ones lack.

Most globes, being cardboard, aren’t amenable to having game pieces cling to them. [madkins9] thus fabricates a steel globe from a pair of pre-purchased hemispheres. Magnets firmly affixed to the bases of all game pieces allow them to stick firmly to the spherical play surface. In a “learn from my mistakes” moment, [madkins] suggests that if you use two pre-made hemispheres, as he did, you make sure they balance before welding and painting them.

While those of us with less artistic flair might be tempted to try something like a giant eggbot, [madkins] was able to transfer the Risk world map onto his globe by hand. Many coats of urethane mean it should be well protected from the clicking or sliding magnet pieces, no matter how long the game lasts. In another teachable moment, he suggests not using that sealer over sharpie. Good to know.

Once gameplay is finished, the wooden globe stand doubles as a handsome base to hold all the cards and pieces until the next time you want to end friendships over imaginary world domination. Perhaps try a friendly game of Settlers of Catan instead.