Running A Desktop PC Off AA Alkaline Cells

February 28, 2026 by Maya Posch 2 Comments

Everyone is probably familiar with the concept of battery-powered devices, but generally, this involves a laptop with a beefy battery pack and hardware optimized for low power draw. You could also do the complete opposite and try to run a desktop PC off alkaline AA cells, as [ScuffedBits] recently did out of morbid curiosity. Exactly how many alkaline cells does it take to run a desktop PC for any reasonable amount of time?

One nice thing about using batteries with a desktop PC is that you can ditch the entire AC-DC power conversion step and instead use a DC-DC adapter like the well-known PicoATX and its many clones. These just take in 12 VDC and tend to have a fairly wide input voltage range, which is useful when your batteries begin to run out of juice. In this case, just above 10 VDC seemed to be the cut-off point for the used DC-DC adapter.

In the end, [ScuffedBits] used what looks like 56 alkaline AA cells connected in both parallel and series, along with two series-connected 6,800 µF, 40V electrolytic capacitors to buffer the spikes in power demand, after early experiments showed that the cells just cannot provide power that quickly. Although admittedly, the initial thin wiring didn’t help either. With alkaline rather than carbon AA cells, improved wiring, and some buffer capacitors, it turns out that you can indeed run a desktop PC off AA cells, if only just about long enough for a small game of Minesweeper.

Amusingly, the small LCD monitor used in the experiment drew so little power that it happily ran on eight NiMH cells for much longer, highlighting just how important power conservation is for battery-powered devices. We wonder if you could marry this project to a battery project we saw and end up with something practically portable?

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The Only Snail You Want In Your Garden Is A Seed-Starting Hack

February 28, 2026 by Tyler August 1 Comment

As temperatures warm up in the Northern Hemisphere, one’s mind naturally turns to the outdoors and the garden — even if some of our gardens are still snow-covered. One secret to good gardening is that many of the plants we love take too long to grow if started from seed outside, at least in relatively temperate climes. There are a myriad of ways to grow seedlings indoors, and this new hack highlighted by [GrowVeg] looks like a great way to get started.

The idea apparently comes from the seedier side of Instagram, where [Farida Sober] has been popularizing it as a “seed snail”, a name they seem to have coined. The technique is very simple: take a sheet of something cheap that won’t disintegrate when moist like bubble wrap or cardboard, layer it with soil — up to 5 cm depending on your seed size — and you roll the whole thing up like a piece of sushi to produce the spiral shape that gives the hack its name. With a piece of tape to hold the roll, it’s just a matter of planting your seeds according to the packet directions. If that’s clear as mud, check out the video embedded below.

Once the seedlings have grown, it looks like it will be very easy to unroll the spiral and pluck them out to plant in the ground or bigger pots without overly traumatizing their roots, like we always do starting in flats. If it weren’t for those delicate roots, it certainly looks like the snail might save some space compared to, say, peat pots. Just remember that starting under the proper LEDs can make a huge difference to how quickly your seeds grow. No dirt? No problem — once sprouted, your plants can be made to grow hydroponically. For the really adventurous, there’s even aeroponics.

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The Joys Of 3D Printing

February 28, 2026 by Elliot Williams 15 Comments

Al and I were talking on the podcast today about a sweet 3D printed wide-format camera build, and we got to musing on why we 3D-print.

For Al, it’s an opportunity to experiment with 3D printing itself: tweaking his machines to get the best performance out of them. Other people make small, functional objects that they need in their daily life, like bag clips or spare parts for broken appliances. Some folks go for the ornamental or the aesthetic. The kids in my son’s class all seem obsessed with sci-fi props and fidget toys. The initial RepRap ideal was to replace all commercial fabrication with machines owned by the individual, rather than by companies – it was going to be Marxist revolutionary.

But there’s another group of 3D printer enthusiasts that I think doesn’t get enough coverage, and I’m going to call them the hobbyist industrial designers. These are the people who design a custom dog-poop-bag holder that exactly fits their extra-wide dog leash, not because they couldn’t find one that fit in the pet store, but because it’s simply fun to design and fabricate things. (OK, that’s literally me.)

It’s fun to learn CAD tools, to learn about how things are designed, how they work, and how to manufacture them at least in quantity one. Dreaming, designing, fabricating, failing, and repeating until you get it right is a great joy. And then you get to use the poop-bag holder every day for a few years, until you decide to refine the design and incorporate the lessons learned on the tough streets of practical use.

Of course none of this is exclusive to 3D printing. There were always people who designed-and-built things in the metal machine shop, or made their creations out of wood. In that sense, the 3D printer is just another tool, and the real fun isn’t in using the 3D printer, but rather in the process of bringing things out of your mind and into the world. So maybe there is nothing new here, but the latitude that 3D printing affords the hobby designer is amazing, and that makes it all the more fun, and challenging.

So do you 3D print for necessity, to stick it to the man, to pimp your printer, for the mini-figs, or simply for the joy of the process of making things? It’s all good. 3D printing is a big tent.

3D Print This MRI Safe Torque Wrench If You’re Rich

February 28, 2026 by Lewin Day 8 Comments

MRI machines come with a variety of safety warnings. Perhaps most importantly, you have to be very careful not to take ferrous metal objects anywhere near them, since strong magnetic fields can send them flying, causing damage and injuries. To that end, you might find yourself in need of magnetically-safe tools when working on such machines. [Sam Schmitz] recently whipped up a nifty example of an MRI-safe torque wrench himself.

The torque wrench mechanism, which operates in one direction only.

It’s a 3D printed design which can be produced on a Formlabs Fuse 1+ as a single piece in nylon using a selective laser sintering process. The torque wrench works in a deceptively simple manner. As the handle is rotated, a flap mates with the flat side of a fin on the shaft. This allows the shaft to turn. However, apply more than 0.6 Nm of torque, and the fin will eventually give in, snapping over the lip and stopping any further rotation that would over-tighten the fastener. [Sam] suggests these printed torque wrenches largely come out to the correct torque spec when printed, and can survive a thousand cycles or more while remaining in a usable spec.

The wrench does have one drawback though—it is apparently painfully loud to use. When the handle snaps past the detent, the “click” is quite piercing. [Sam] has measured the sound at up to 125 dB. Not exactly the best when it comes to ear safety!

If you work on MRI machines regularly, you already have the tooling to do your job. However, it’s neat to see that such a specialized tool can be easily and reliably 3D printed… with the slight drawback that you need a $60,000 SLS printer to do it. SLS isn’t readily available at the DIY level just yet, but it is slowly getting there. We’re waiting with bated breath.

NaCl Casting Technique Really Earns Its Salt

February 28, 2026 by Tyler August 9 Comments

Sodium Chloride has a melting point of 801 C (1,474 F), putting it comfortably between commonly-cast materials like aluminum and bronze. Which led to [Robinson Foundry] asking the question: can you cast salt like a metal? The answer, surprisingly, was yes!

[Robinson] tries casting the salt with two different methods: like it was glass, and like it was metal. In the glass-like casting, he packs a ceramic mold with salt and tosses it into an electric kiln, there to melt and very slowly cool. In metal-like casting, he just tosses salt into a crucible and melts it in the same beer-can kiln we saw when we featured his lost-pla casting a while back. The molten salt is poured very carefully into sand casting molds. If you’re familiar with the technique, you can skip to about 5:20 when he does the reveal.

As it turns out, the sand casting works out much better. While the glass-style casting in the electric kiln grew much larger crystals and so is more translucent, it’s also stuck completely inside the porous ceramic. Perhaps the ceramic would need glazed to pull off that technique?

On the other hand, the sand reacts with the salt in some way– molten salt isn’t exactly a noble gas, after all–to create a lovely gunmetal finish to the parts. They almost look like metal, though the brittleness gives away the game when he opens the mold to show a dagger in several pieces. For the decorative busts and megalodon teeth in the test, though, it is a great success.

Now, we’re not going to say this video came about because of high metal prices, or comment on what sort of trade policies might be driving up the price of metals like aluminum in the USA, but we do think this a great hack. While salt-based castings are obviously going to have very different physical properties than metal, for decorative work, it creates a lovely finish out of a material that’s cheap as dirt. Hopefully he comes back to the glass-style casting; we would not want to trust that black coating around food, and a salt crystal salt shaker sounds too good to pass up.

The only times we’ve seen molten salt around here is in nuclear reactors, and in homemade batteries, though that first one obviously wasn’t table salt.

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Evolved Nerf RC Tank Now Leaves Welts

February 27, 2026 by Donald Papp 5 Comments

[Joshua Clay] recently unveiled his newest RC Nerf Dart Robot and talks through his design choices, pointing out that in his aim to have it launch darts fast and hard he may have somewhat overshot the mark. He found out first hand during testing that it shoots hard enough to leave welts through a sweatshirt and probably should be downgraded a bit. Thankfully, one of the features of his new unit is a highly modular design that makes iterating easier than ever.

A modular, glue-free assembly that leaves wiring accessible helps make design iterations faster and easier.

This model is an evolution of his first Nerfbot, and the new one is a smaller, tighter design that trades a wheeled base for a tracked one, among other changes.

The tank platform is one example of [Joshua] using affordable, off-the-shelf solutions where it makes sense to do so. For example, the inexpensive tank-track platform means he can focus on the rest of the bot without having to design or make his own tank treads. Similarly, to control the bot he opts for a PlayStation 4 controller, paired to the bot over Bluetooth. It’s high quality, inexpensive, commonly available, and easily interfaced with the RP2040 that runs the show.

[Joshua] aims for a modular, LEGO-inspired mechanical assembly that makes maintenance, wiring, and iteration as easy as possible. We especially like how the battery, wiring, and things like gears for the pan-and-tilt mechanism of the Nerf launcher are easily accessible.

The dart launcher uses two flywheels to grip and propel each dart fed from a high-capacity magazine, and you can watch it move and shoot around the 9:44 mark in the video, embedded below. It’s plenty loud, but the camera is barely able to register darts leaving the barrel.

If you like the looks of [Joshua]’s newest Nerfbot, keep an eye out because he’s got more to share about it and is considering other features like a camera. In the meantime, there are a few more photos on his website.

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Philco Bet The Farm On The Predicta… And Lost

February 27, 2026 by Al Williams 20 Comments

Philco was a common household brand for many years. The company started in 1892, making street lights. Then they pivoted to batteries. This was big business when early radios were all battery-operated. But in the 1920s, line-powered radios threatened to shrink their customer base, so they pivoted again. This time, they started making radios. So what happened? [The Last Shift] has the story, and you can see the video below.

Philco used advanced manufacturing techniques to make radios more affordable. By 1930, they were the number one radio maker in the world. After World War II, they moved into everything electric: mostly appliances, but also the new king of the electronics market, the television.

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