Wireless USB Autopsy

May 7, 2025 by Al Williams 22 Comments

It might seem strange to people like us, but normal people hate wires. Really hate wires. A lot. So it makes sense that with so many wireless technologies, there should be a way to do USB over wireless. There is, but it really hasn’t caught on outside of a few small pockets. [Cameron Kaiser] wants to share why he thinks the technology never went anywhere.

Wireless USB makes sense. We have high-speed wireless networking. Bluetooth doesn’t handle that kind of speed, but forms a workable wireless network. In the background, of course, would be competing standards.

Texas Instruments and Intel wanted to use multiband orthogonal frequency-division multiplexing (MB-OFDM) to carry data using a large number of subcarriers. Motorola (later Freescale), HP, and others were backing the competing direct sequence ultra-wideband or DS-UWB. Attempts to come up with a common system degenerated.

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Liquid Silicone 3D Printing Is No Joke

May 7, 2025 by Tyler August 45 Comments

They might call it Levity, but there’s nothing funny about Rapid Liquid Print’s new silicone 3D printer. It has to be seen to be believed, and luckily [3D Printing Nerd] gives us lots of beauty shots in this short video, embedded below.

Smooth, and *fast*. This bladder took 51 minutes according to the RLP website.

Printing a liquid, even a somewhat-viscous one like platinum-cure silicone, presents certain obvious challenges. The Levity solves them with buoyancy: the prints are deposited not onto a bed, but into a gel, meaning they are fully supported as the silicone cures. The fact that the liquid doesn’t cure instantly has a side benefit: the layers bleed into one another, which means this technique should (in theory) be stronger in all directions than FDM printing. We have no data to back that up, but what you can see for yourself that the layer-blending creates a very smooth appearance in the finished prints.

If you watch the video, it really looks like magic, the way prints appear in the gel. The gel is apparently a commercially-available hydrogel, which is good since the build volume looks to need ̶a̶b̶o̶u̶t̶ ̶5̶0̶0̶ ̶L̶ at least 125 L of the stuff. The two-part silicone is also industry-standard and off-the-shelf, though no doubt the exact ratios and are tweaked for purpose. There’s no magic, just a really neat technology.

If you want one, you can sign up for the waiting list at Rapid Liquid Print’s website, but be prepared to wait; units ship next year, and there’s already a list.

Alternatively, since there is no magic here, we’d love to see someone take it on themselves, the way once equally exotic SLS printers have entered the DIY world. There was a time when resin printers were new and exotic and hobbyists had to roll their own, too. None of this is to say we don’t respect the dickens out of the Rapid Liquid Print team and their achievement–it’s just that imitation is the sincerest form of flattery. Continue reading “Liquid Silicone 3D Printing Is No Joke” →

FLOSS Weekly Episode 832: Give Yourself A Medal

May 7, 2025 by Jonathan Bennett No comments

This week, Jonathan Bennett chats with Alexandre Dulaunoy and Quentin Jérôme about Kunai and CIRCL! How does Kunai help solve Linux security monitoring? Why is eBPF the right place for one of these tools to run? And how is CIRCL helping Luxembourg and the world deal with the modern security landscape? Watch to find out!

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Cabinentaxi layout as it existed in 1978, with labels by the Tim Traveller YT channel.

Germany’s Cabinentaxi: The Double-Sided Monorail That Wasn’t Meant To Be

May 7, 2025 by Maya Posch 14 Comments

The 1970s was a perfect time for alternative modes of transport to be trialed that might replace cars in the wake of the global oil crisis. One of these was the Cabinentaxi, or C-Bahn as it was later called, which was a variation on the standard suspended and monorail concepts.

It was a people mover concept, with ‘pods’ (or cabins) that’d ride either on top of or below the suspended track. It was tested intensively over the course of six years, performed admirably, and completely failed to materialize commercially due to budget crunch times around the world.

Recently [Tim Traveller] went to the muddy farm field that once housed the big test track (pictured above), of which nothing remains but the gates and a sign. Despite the fact that few people have heard of Cabinentaxi prior to seeing [Tim]’s video or reading this, there is a big Wikipedia entry on it, as well as a (German language) site dedicated to the technology.

What made the C-Bahn different from trains and buses were the smaller pods, high throughput capacity and ability to call a pod on demand at any of the stations. This kind of flexibility is what is seen more or less with today’s people moving systems at airports and some cities, except the C-Bahn was classified as a personal rapid transport (PRT), with on-demand pods that could travel between any two stations without stopping or delays. This is something that isn’t seen with public transport today, even if self-driving cars purport to one day do this kind of trick.

Considering that this technology died most due to economical circumstances, we remain hopeful to see its revival one day.

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Big Chemistry: Cement And Concrete

May 7, 2025 by Dan Maloney 24 Comments

Not too long ago, I was searching for ideas for the next installment of the “Big Chemistry” series when I found an article that discussed the world’s most-produced chemicals. It was an interesting article, right up my alley, and helpfully contained a top-ten list that I could use as a crib sheet for future articles, at least for the ones I hadn’t covered already, like the Haber-Bosch process for ammonia.

Number one on the list surprised me, though: sulfuric acid. The article stated that it was far and away the most produced chemical in the world, with 36 million tons produced every year in the United States alone, out of something like 265 million tons a year globally. It’s used in a vast number of industrial processes, and pretty much everywhere you need something cleaned or dissolved or oxidized, you’ll find sulfuric acid.

Staggering numbers, to be sure, but is it really the most produced chemical on Earth? I’d argue not by a long shot, when there’s a chemical that we make 4.4 billion tons of every year: Portland cement. It might not seem like a chemical in the traditional sense of the word, but once you get a look at what it takes to make the stuff, how finely tuned it can be for specific uses, and how when mixed with sand, gravel, and water it becomes the stuff that holds our world together, you might agree that cement and concrete fit the bill of “Big Chemistry.”

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Diagram showing the structure of the base.

Magic On Your Desk Via MagLev Toy

May 7, 2025 by Tyler August 9 Comments

Magnets aren’t magic, but sometimes you can do things with them to fool the uninitiated — like levitating. [Jonathan Lock] does that with his new maglev desk toy, that looks like at least a level 2 enchantment.

This levitator is USB-powered, and typically draws 1 W to 3 W to levitate masses between 10 g and 500 g. The base can provide 3 V to 5 V inductive power to the levitator to the tune of 10 mA to 50 mA, which is enough for some interesting possibilities, starting with the lights and motors [Jonathan] has tried.

In construction it is much like the commercial units you’ve seen: four permanent magnets that repel another magnet in the levitator. Since such an arrangement is about as stable as balancing a basketball on a piece of spaghetti, the permanent magnets are wrapped in control coils that pull the levitator back to the center on a 1 kHz loop. This is accomplished by way of a hall sensor and an STM32 microcontroller running a PID loop. The custom PCB also has an onboard ESP32, but it’s used as a very overpowered USB/UART converter to talk to the STM32 for tuning in the current firmware.

If you think one of these would be nice to have on your desk, check it out on [Jonathan]’s GitLab. It’s all there, from a detailed build guide (with easy-to-follow animated GIF instructions) to CAD files and firmware. Kudos to [Jonathan] for the quality write-up; sometimes documenting is the hardest part of a project, and it’s worth acknowledging that as well as the technical aspects.

We’ve written about magnetic levitation before, but it doesn’t always go as well as this project. Other times, it very much does. There are also other ways to accomplish the same feat, some of which can lift quite a bit more.

Tracking The Sun? Nah!

May 7, 2025 by Al Williams 43 Comments

If you want solar power, you usually have to make a choice. You can put a solar panel in a fixed location and accept that it will only put out the maximum when the sun is properly positioned. Or, you can make the panels move to track the sun.

While this isn’t difficult, it does add cost and complexity, plus mechanical systems usually need more maintenance. According to [Xavier Derdenback], now that solar panels are cheaper than ever, it is a waste of money to make a tracking array. Instead, you can build a system that looks to the east and the west. The math says it is more cost effective.

The idea is simple. If you have panels facing each direction, then one side will do better than the other side in the morning. The post points out that a tracking setup, of course, will produce more power. That’s not the argument. However, for a given power output, the east-west solution has lower installation costs and uses less land.

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