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Pi Networks the Smith Chart Way

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[Ralph] is excited about impedance matching, and why not? It is important to match the source and load impedance to get the most power out of a circuit. He’s got a whole series of videos about it. The latest? Matching using a PI network and the venerable Smith Chart . We like that he makes each video self-contained. It does mean if you watch them all, you get some review, but that’s not a bad thing, really. He also does a great job of outlining simple concepts, such as what a complex conjugate is, that you might have forgotten. Smith charts almost seem magical, but they are really sort of an analog computer. The color of the line and even the direction of an arrow make a difference, and [Ralph] explains it all very simply. The example circuit is simple with a 50 MHz signal and a mismatched source and load. Using the steps and watching the examples will make it straightforward, even if you’ve never used a Smith Chart before. The red lines plot impedance, and the blue lines show co...
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Optimizing Dust Separation for Extreme Efficiency

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[Ruud], the creator of [Capturing Dust], started his latest video with what most of us would consider a solved problem: the dust collection system for his shop already had a three-stage centrifugal dust separator with more than 99.7% efficiency. This wasn’t quite as efficient as it could be, though, so [Ruud]’s latest upgrade shrinks the size of the third stage while increasing efficiency to within a rounding error of 99.9%. The old separation system had two stages to remove large and medium particles, and a third stage to remove fine particles. The last stage was made out of 100 mm acrylic tubing and 3D-printed parts, but [Ruud] planned to try replacing it with two parallel centrifugal separators made out of 70 mm tubing. Before he could do that, however, he redesigned the filter module to make it easier to weigh, allowing him to determine how much sawdust made it through the extractors. He also attached a U-tube manometer (a somewhat confusing name to hear on YouTube) to measure ...
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Linear Solar Chargers for Lithium Capacitors

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For as versatile and inexpensive as switch-mode power supplies are at all kinds of different tasks, they’re not always the ideal choice for every DC-DC circuit. Although they can do almost any job in this arena, they tend to have high parts counts, higher complexity, and higher cost than some alternatives. [Jasper] set out to test some alternative linear chargers called low dropout regulators (LDOs) for small-scale charging of lithium ion capacitors against those more traditional switch-mode options. The application here is specifically very small solar cells in outdoor applications, which are charging lithium ion capacitors instead of batteries. These capacitors have a number of benefits over batteries including a higher number of discharge-recharge cycles and a greater tolerance of temperature extremes, so they can be better off in outdoor installations like these. [Jasper]’s findings with using these generally hold that it’s a better value to install a slightly larger solar cell ...
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Rust Drives a Linux USB Device

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In theory, writing a Linux device driver shouldn’t be that hard, but it is harder than it looks. However, using libusb, you can easily deal with USB devices from user space, which, for many purposes, is fine.  [Crescentrose] didn’t know anything about writing user-space USB drivers until they wrote one and documented it for us. Oh, the code is in Rust, for which there aren’t as many examples. The device in question was a USB hub with some extra lights and gadgets. So the real issue, it seems to us, wasn’t the code, but figuring out the protocol and the USB stack. The post covers that, too, explaining configurations, interfaces, and endpoints. There are other ancillary topics, too, like setting up udev. This lets you load things when a USB device (or something else) plugs in. Of course, you came for the main code. The Rust program is fairly straightforward once you have the preliminaries out of the way. The libusb library helps a lot. By the end, the code kicks off some thread...
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Simulating Empires with Procedurally Generated History

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Procedural generation is a big part of game design these days. Usually you generate your map, and [Fractal Philosophy] has decided to go one step further: using a procedurally-generated world from an older video, he is procedurally generating history by simulating the rise and fall of empires on that map in a video embedded below. Now, lacking a proper theory of Psychohistory, [Fractal Philosophy] has chosen to go with what he admits is the simplest model he could find, one centered on the concept of “solidarity” and based on the work of [Peter Turchin], a Russian-American thinker. “Solidarity” in the population holds the Empire together; external pressures increase it, and internal pressures decrease it. This leads to an obvious cellular automation type system (like Conway’s Game of Life), where cells are evaluated based on their nearest neighbors: the number of nearest neighbors in the empire goes into a function that gives the probability of increasing or decreasing the solidarit...
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Ceramic Printing Techniques for Plastic

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[Claywoven] mostly prints with ceramics, although he does produce plastic inserts for functional parts in his designs. The ceramic parts have an interesting texture, and he wondered if the same techniques could work with plastics, too. It turns out it can , as you can see in the video below. Ceramic printing, of course, doesn’t get solid right away, so the plastic can actually take more dramatic patterns than the ceramic. The workflow starts with Blender and winds up with a standard printer. The example prints are lamps, although you could probably do a lot with this technique. You can select where the texturing occurs, which is important in this case to allow working threads to avoid having texture. You will need a Blender plugin to get similar results. The target printer was a Bambu, but there’s no reason this wouldn’t work with any FDM printer. We admire this kind of artistic print. We’ve talked before about how you can use any texture to get interesting results . If you need ...
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Homebrew Pockels Cell Is Worth the Wait

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We haven’t seen any projects from serial experimenter [Les Wright] for quite a while, and honestly, we were getting a little worried about that. Turns out we needn’t have fretted, as [Les] was deep into this exploration of the Pockels Effect , with pretty cool results. If you’ll recall, [Les]’s last appearance on these pages concerned the automated creation of huge, perfect crystals of KDP , or potassium dihydrogen phosphate. KDP crystals have many interesting properties, but the focus here is on their ability to modulate light when an electrical charge is applied to the crystal. That’s the Pockels Effect, and while there are commercially available Pockels cells available for use mainly as optical switches, where’s the sport in buying when you can build? As with most of [Les]’s projects, there are hacks galore here, but the hackiest is probably the homemade diamond wire saw. The fragile KDP crystals need to be cut before use, and rather than risk his beauties to a bandsaw or angle g...
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