Author: Al Williams

4336 Articles

PC Case Makes Portable Power Supply

October 21, 2023 by 4 Comments

Recently, we’ve seen a lot of semi-portable power stations. These have some big rechargeable battery and various connection options. [Dereksgc] wanted to make his own and decided the perfect housing would be a small PC tower case. (Video, embedded below.) It makes sense. There are plenty of easy-to-work front panel inserts, a power supply box with an AC cord (the power supply is long gone), and it is big enough to fit the battery. You can see the result in the video below.

The bulk of the work was installing power supply modules and a charge controller on floppy disk blank panels. The battery — a 50 Ah LiFePO4 unit — fits nicely in the bottom. Some of the buttons and connectors find use in the new incarnation.

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CPU Cooler In A Printer’s Hot End

October 21, 2023 by 9 Comments

[Proper Printing] often does unusual 3D printer mods. This time, he’s taking a CPU cooler made for a Raspberry Pi with some heat pipes and converting it into a 3D printer hot end. Sound crazy? It is even crazier than it sounds, as seen in the video below.

Heat pipes contain a liquid and a wick, so bending them was tricky. It also limited the size of the heat break he could use since the two heat pipers were relatively closely spaced. Once you have the cooler reshaped and a threaded hole for the heatbreak, the rest is anticlimactic. The heatbreak holds a heat block that contains the heating element and temperature sensor. A few changes were needed to the custom extruder cut out of acrylic, but that didn’t have anything to do with the fan and mount.

Normally, a hot end assembly has a substantial heat sink, and a fan blows air over it. The heat pipe technique is a common way to move heat away from a tight space. So, the way it is used here is probably not very useful compared to a conventional technique. However, we can imagine tight designs where this would be viable.

Heat pipes aren’t the same as water cooling, even though some use water inside. A heat pipe is a closed system. The fluid boils off at the hot end, condenses at the cool end, and wicks the liquid back to close the cycle. On the other hand, you can use more conventional water cooling, too.

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Pocket Calculator Isn’t A Brain Or Magic

October 20, 2023 by 18 Comments

If you predate the pocket calculator, you may remember slide rules. But slide rules take a a little skill to use. There was a market for other devices that were simpler or, in some cases, cheaper. One common one was the “magic brain” or Addiator which was a little metal box with some slots that could add numbers. However, using clever tricks it could also subtract and — in a fashion — multiply. [Our Own Devices] has a teardown of the device you can see in the video below. It is deceptively simple, and the description of how it works is at least as interesting as the peek inside.

We remember these on the market and, honestly, always thought they were simple tally mechanisms. It turns out they are both less and more than that. Internally, the device is a few serrated sheet metal strips in a plastic channel. The subtraction uses a complement addition similar to how you do binary subtraction using 2’s complement math. Multiplication is just repetitive addition, which is fine for simple problems.

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NFTs And Tulipmania: A Little Bit Of History Repeating

October 20, 2023 by 123 Comments

We were not surprised to read that a company that tracks NFTs declared that most NFTs are now worthless. But the NFT — non-fungible token — market was huge, so around 23 million people invested in NFTs that are now worth nothing. Worse still, the company notes that because of oddities in how NFTs are priced, the real number of worthless assets is probably even greater than they think.

It is easy to look back and think that it was obvious. After all, an NFT of the Mona Lisa isn’t really the Mona Lisa. Nor does owning it confer any real benefit other than “bragging rights” of owning an NFT of the Mona Lisa. But that’s like saying Luke should have known Darth Vader was his father — it’s only evident after the fact. History is replete with bad ideas at the time that paid out down the road. Of course, history is also full of bad ideas that were simply bad ideas. For every Apple or Google stock you didn’t buy at $4 a share, there are a hundred $4 stocks that you shouldn’t have bought.

The Virus

The NFT craze was sort of a viral event. We usually think of these as part of the Internet culture, but that’s not really true. There is actually very little new on the Internet. The Internet just lets things reach further and faster than before.

Don’t believe me? Kilroy was a viral meme in the 1940s. Fads such as hula hoops, phone booth stuffing, and flagpole sitting were the ice bucket challenges of their day. But, of course, these things weren’t economic. Just fun fads. But economic fads that turn out to be a bad idea are nothing new, either.

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An Explosive Look At Detonators

October 20, 2023 by 17 Comments

If you’ve ever watched a cartoon where something blows up, you’ve probably seen a detonator — the device with a plunger that, when you push it, some dynamite blows up a bridge or a building or whatever. Detonators may be common in cartoons, but they are very real, and [Our Own Device] talks about some vintage detonators and, along the way, gives a brief history of explosive compounds.

For many years, black powder — a low explosive — was the only game in town. But a flurry of scientific advances brought a new class of high explosives far more powerful than gunpowder. The story of antique explosive factory safety measures, and lack thereof, is also an interesting side detour.

We enjoyed the trip down memory lane. However, if you want to skip the history lesson, jump about 17 minutes in to get a better look at the hardware. The teardown follows soon thereafter. These boxes are built solidly and have many safety features to prevent accidental detonations. One is a dynamo device with some clever mechanisms to ensure that the unit produces enough voltage, the other uses a charged capacitor.

Our usual interest in pyrotechnics is usually aimed more at fireworks. You think of explosives as having an imprecise effect, but that isn’t necessarily the case.

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Linux Fu: Deep Git Rebasing

October 17, 2023 by 22 Comments

If you spend much time helping people with word processor programs, you’ll find that many people don’t really use much of the product. They type, change fonts, save, and print. But cross-references? Indexing? Largely, those parts of the program go unused. I’ve noticed the same thing with Git. We all use it constantly. But do we? You clone a repo. Work on it. Maybe switch branches and create a pull request. That’s about 80% of what you want to do under normal circumstances. But what if you want to do something out of the ordinary? Git is very flexible, but you do have to know the magic incantations.

For example, suppose you mess up a commit message — we never do that, of course, but just pretend. Or you accidentally added a file you didn’t want in the commit. Git has some very useful ways to deal with situations like this, especially the interactive rebase.

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[Ken] Looks At The 386

October 16, 2023 by 27 Comments

The 80386 was — arguably — Intel’s first modern CPU. The 8086 was commercially successful, but the paged memory model was stifling. The 80286 also had a protected mode, which differed from the 386’s. [Ken Shirriff] takes the 386 apart for us in a recent blog post.

The 286’s protected mode was less successful than the 386 because of several key limitations as it was a 16-bit processor with a 24-bit address bus. It still required segment changes to access larger amounts of memory, and it had no good way to call back into real mode for compatibility reasons. The 386 fixed all that. You could adopt a segment strategy if you wanted to. But you could also load the segment registers once to point to a 4 GB linear address space and then essentially forget them. You also had a virtual 86 mode that could simulate real mode with some work.

The CPU used a 1-micron process, compared to the 1.5-micron process used earlier. The chip had 285,000 transistors (although the 80386SL had many more). That was ten times the number of devices on the 8086. The cheaper 386SX did use the 1.5 micron process for a while, but with a 16-bit external bus, this was feasible. While 285,000 sounds like a lot, a Core i9 has around 4.2 billion transistors. Times have changed.

A smaller design also allowed chips like the 386SL for laptops. The CPU took up only about a fourth of the die. The rest held bus controllers and cache interfaces to cut costs on laptops. That’s why it had so many more transistors.

[Ken] does his usual in-depth analysis of both the die and the history behind this historic device. We spent a lot of time writing protected mode 386 code, and it was nice to see the details of a very old friend. These days, you can get a pretty capable CPU system on a solderless breadboard, but designing a working 386 system took a few extra parts. The 80286 was a stepping stone between the 8086 and 80386, but even it had some secrets to give up.