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A Sloshing-Mercury-Powered Neon Light

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In 1675, while transporting a barometer by night, the astronomer Jean Picard noticed a glow inside its glass tube, just above the mercury. As the mercury sloshed and splashed across the surface of the glass, a static electric charge had built up, which was discharging by ionizing the residual gas molecules inside the evacuated tube. [Styropyro] recreated this effect , and found that the dim glow could be made much stronger by adding some noble gas to the tube. It starts with a simple recreation: he took a volumetric flask, attached a narrow glass stem to the mouth, added some mercury to the flask, evacuated it with a vacuum pump, and sealed off the glass stem. This produced a faint glow when shaken, but it was only really visible under very low light. When [Styropyro] brought it near a Tesla coil, however, it did glow much more brightly. Backfilling an identical flask with neon to about 40 millitorr produced a much more spectacular result (a low pressure in the tube is necessary, bu...
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White Rails are the Infrastructure Hack We Didn’t Know We Needed

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Railroads might be a nineteenth century technology, but they’re still the backbone of cargo transportation in the 21st century. They’ve also far from run out of innovation, including this one which really just sounds like a hack: painting the rails white to beat the heat . In the old days, when rails were short and riveted together, this might have been unecesssary; all those joints allowed for a lot of flex. But when you have kilometers of continously welded rail, the thermal expansion starts to matter. A lot. Even if the rails haven’t bent and buckled from excess heat, their capacity goes down. Trains must therefore slow way, way down in hot weather, reducing the overall amount of freight the system can handle. So, how do you cool the million miles of metal that holds a country together? Paint. Simple white paint sprayed on the side of the rails can bring down temperatures 11 °C (20 °F), according to the Union Pacific Railroad, the first to try this in North Americ...
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A USB Port by Any Other Color…

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[Dr. Gough] bought a generic USB 3.0 hub on an Asian website. Surely, USB 3 is mature enough that even the cheapest hub will have some IC in it that will work well, right? You’d think so, but a little exploratory surgery showed that the only thing about this hub that was USB 3 were the blue port connectors . We have a few problem USB hubs ourselves, so it might be worth doing this to any you have lying around. The first clue: most of the connectors on the PCB only have four pins. On closer examination, the hub appears to be a USB 3.0 extension cable with a USB 2.0 hub made from two HS8836A chips. Not only are these USB 2-only, but all the ports on an HS8836A also share the same USB 1.1 bandwidth. Some hubs can provide multiple ports full 1.1 bandwidth, using the higher-speed USB protocol to the PC as a backhaul. There were quite a few other issues. Missing solder, cables soldered to the board directly, and no bypass capacitors. The per-port switches cut off USB power, but that...
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Bad Apple on a Karaoke Machine

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CD+Graphics was a format that never really caught on. It let music discs pack some graphics, maybe liner notes, and mostly song lyrics into the otherwise empty space on a CD. It was never intended for displaying full-motion video, but that didn’t stop [Adam Gashlin] from getting a Bad Apple, with lyrics, running on any device that will play CD+G . The main challenge is that CD+G gives you 300 screen commands per second, which is plenty for updating text on the 48×16 blocks as the lyrics scroll by. But if you want to send custom blocks and draw images, that’s 2.5 seconds per screen: a lousy framerate. [Adam]’s first trick is to drop the resolution way down, which gets him into the 8 FPS range. Only update the blocks that change pushes this up to a respectable 17-20 FPS. But you can see the updates, and that’s distracting. It really needed buffering. If you don’t know Bad Apple , it’s in black and white. And like many old graphics engines of the...
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Pinch Puts an Arduino On a USB-C Connector

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Compared to the Arduino Uno of old, modern microcontrollers are absolutely tiny — especially for the amount of processing power and I/O you get. But if you need something  really small, like fits-on-the-tip-of-your-finger small, most of the turn-key development boards on the market are still a bit too big. Enter the pinch from moddo , which they advertise as “The World’s Smallest 32-Bit Arduino- Compatible Board.” We can’t vouch for its world-record status, but we certainly can’t think of a smaller one. At least not a complete solution like this, which offers native USB and 15 GPIO pins in addition to the usual suspects like SPI, I2C, PWM, and UART. In fact, it’s so small that it even includes a breakout board to make prototyping a bit easier. Coming from something like an ESP32, the biggest adjustment will probably be working around the relatively limited specs of the SAMD11. The ARM Cortex-M0+ under the hood tops out at 48 MHz, and there...
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DOOM runs (slowly) in a IBM PC-Compatible CSS Sheet

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Just when you thought we’d run out of things to port DOOM to, here comes [Ahmed Amer] with his CSS-DOS, a massive 300 MB CSS style sheet, that runs not just DOS, but Windows 1.0 and, of course, DOOM . The CSS sheet isn’t holding a DOOM port this time, though — it’s holding a full IBM PC compatible, with a simulated 8086, 640 kB of RAM, floppy and VGA controllers. Yes, in one style sheet. We did mention it was 300 MB, right? CSS is not a very good programming language. It’s got functions and if statements nowadays, but it doesn’t really do programs in the usual sense. That is, lists of instructions that feed one into another. You can’t change a variable without jumping through hoops. The sort of static behavior you get from a CSS sheet actually matches hardware architecture better than software, which was the key insight [Ahmed] had to make the project possible. It’s still not easy, or elegant, or perhaps even sane , as you can find out ...
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Cut And Fold Your 3D Printer’s Next Cover

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[cmh]’s  ultra-simple top cover for the Snapmaker U1 3D printer has a 3D model, but don’t let that fool you. There’s no 3D printing at all involved in this project. Rather, the model is a reference shape for making an effective top cover out of cardboard or corrugated plastic sheet (also known as Coroplast) which is what [cmh] used. The pattern can be cut from a single sheet, or from multiple pieces taped together. Corrugated plastic is a versatile option for things like printer enclosures. It’s cheap, a good insulator, easy to cut, and available from just about any plastics supplier. We’ve made the case that they’re a good alternative to acrylic sheets for printer enclosures, but [cmh] goes even further with a design that requires no additional hardware whatsoever. Assembly doesn’t even require more than tape, really. He provides a cutout diagram for pieces that, when assembled, make a sort of hat that is just right to cover the top of the...
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