A rectangular box with a purple section sandwiched between two red sections sits on a black tabletop. The end of the box is open. Black and red wires run out of the back of the box to a breadboard.

Improving Wind Turbine Testing With A Better Air Source

June 17, 2024 by 16 Comments

When comparing the efficiency of different wind turbine blade designs, [AdamEnt] found using a hair dryer wasn’t the best tool for the job. Enter his new 3D-printed wind tunnel.

After several prototypes, [AdamEnt] decided on a design that exploits slicer infill to create a flow straightener without having to do any tedious modeling of a lattice. Combined with a box on both ends of the straightener to constrain the flow, he has a more controllable air source with laminar instead of turbulent flow for testing his wind turbines.

The BLDC motor driving the air is attached to a toroidal blade of MIT fame. We get a little bit of the math behind calculating wind turbine efficiency and see a quick test of a blade placed next to the outlet of the air source at the end of the video.

If you’re planning on building your own wind tunnel, we’ve covered a few. We’ve even seen one that goes up to Mach 20, although that probably wouldn’t be useful for wind turbine design!

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Harmonic Table Keyboard Brings Old Idea Back To Life

June 17, 2024 by 11 Comments

If you missed the introduction of the Axis-49 and Axis-64 keyboards by C-Thru Music, you’re definitely not alone. At the time it was a new musical instrument that was based on the harmonic table, but it launched during the Great Recession and due to its nontraditional nature and poor timing, the company went out of business. But the harmonic table layout has a number advantages for musicians over other keyboard layouts, so [Ben] has brought his own version of the unique instrument to life in his latest project.

Called the Midihex, the keyboard has a number of improvements over the version from C-Thru Music, most obviously its much larger 98 playable keys and five function keys. The keys themselves are similar to Cherry MX keys but which use Hall-effect sensors. This style of key allows the device to send continuous key position information to the host computer, and since this is a MIDI instrument, this capability allows it to support a MIDI protocol called MIDI Polyphonic Expression (MPE) which allows each note to be more finely controlled by the musician than a standard MIDI instrument. The PCB is powered by a Teensy 4.1 at the core.

For any musicians that haven’t tried out a harmonic table before, an instrument like this might be worth trying out. The layout provides easier chord and scale patterns, and for beginner musicians it can have a much shallower learning curve than other types of instruments. If you can’t find an original Axis-49 or Axis-64 anywhere to try out, though, we actually posted a teardown of one way back in 2009 when the company was still producing instruments.

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PostmarketOS Now Boots On Over 250 Devices

June 17, 2024 by 43 Comments

Every year, as consumers gobble up the latest Android devices, more old, but perfectly serviceable, units end up collecting dust in drawers. Or worse, they end up getting tossed in the trash. One of the most promising tools we have to help keep these older devices useful is postmarketOS, a full-fledged Linux distribution that provides a flexible and up-to-date software environment on devices that might otherwise be stuck with some old and unsupported version of Google’s mobile operating system.

As of the latest update on the postmarketOS blog, the team has announced an exciting milestone: over 250 devices can now boot the stable release of the OS.

Now to be clear, not all devices will be fully functional. In fact, the blog post clarifies that some of them only barely boot. But it’s progress, and now that these semi-supported devices aren’t hidden behind a development version of the OS, it means more folks will be able to put them to use.

For example, if you want to turn your old smartphone into a low-energy headless webserver, it doesn’t really matter if its display, touchscreen, or speakers are supported. You just need it to boot into Linux and fire up an SSH server so you can get in and start working.

But support for new devices is just one of the additions in this new v24.06 release. The blog post also points out several notable software upgrades, including the move to the 6.x branch of KDE Plasma Mobile. This brings with it a long list of improvements and changes, including a rewritten homescreen with enhanced customization options. If you prefer a more minimal GUI, don’t worry. This new release also updates Sxmo, which provides a menu-driven interface for both touch screens and hardware controls.

Among the newly supported devices is a generic x86_64 image that should work on a wide array of PCs. While obviously there’s no shortage of Linux distros you could run on your old computer, being able to install postmarketOS on it is definitely helpful for development purposes. There’s also a new Tegra ARMv7 target which brings a number of new devices into the fold, such as the Google Nexus 7, and Microsoft Surface RT.

Looking to run postmarketOS on your own hardware? The best way to start is to check the Devices page and see how many of those old gadgets you’ve got collecting dust in a drawer are compatible.

The Solar System Is Weirder Than You Think

June 17, 2024 by 50 Comments

When I was a kid, the solar system was simple. There were nine planets and they all orbited in more-or-less circles around the sun. This same sun-and-a-handful-of-planets scheme repeated itself again and again throughout our galaxy, and these galaxies make up the universe. It’s a great story that’s easy to wrap your mind around, and of course it’s a great first approximation, except maybe that “nine planets” thing, which was just a fluke that we’ll examine shortly.

What’s happened since, however, is that telescopes have gotten significantly better, and many more bodies of all sorts have been discovered in the solar system which is awesome. But as a casual astronomy observer, I’ve given up hope of holding on to a simple mental model. The solar system is just too weird.

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Magic Cane Is The Secret Behind Lightsaber

June 17, 2024 by 23 Comments

Everyone has a lightsaber or two lying around the house, but not everyone has a lightsaber that extends and retracts automatically. And that’s because, in the real world, it’s not an easy design challenge. [HeroTech]’s solution for the mechanism is simple and relies on an old magician’s trick: the appearing cane. (Video, embedded below.)

An appearing cane is a tightly coiled up spring steel sheet that springs, violently, to its full length when a pin is released, but they can’t retract while the audience is looking. This is fine for magic tricks, but a lightsaber has to be able to turn off again. Here, an LED strip does double duty as source of glow but also as the cable that extends and retracts the appearing cane spring. A motor and spool to wind up the LED strip takes care of the rest.

There are still a number of to-dos in this early stage prototype, and the one mentioned in the video is a tall order. Since the strip doesn’t illuminate out the sides, the lightsaber has two good viewing angles, and two bad ones. The plan is to rotate the LED strip quickly inside the sheath: an approach that was oddly enough used in the original movie prop, as demonstrated in this documentary. Doing this reliably in an already packed handle is going to be a challenge.

If you’re thinking you’ve seen a magic-cane lightsaber before, well, maybe you saw this video. And if you want a light saber with real lasers, check out this build that brings its own fog machine. Take that, Darth Vader!

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Preview Markdown In The Terminal With Bash

June 17, 2024 by 12 Comments

Markdown has become an extremely popular way to document source code and other projects, thanks in no small part to how well web-based services like GitHub render it. Just sprinkle a few extra characters into a regular text file, and all of a sudden it looks like you know what you’re doing. Unfortunately, there are some places where markdown won’t actually render, and you’ll be stuck looking at those extra characters.

But thanks to MarCLIdown, the terminal doesn’t have to be one of those places. Written by [NihaAlGhul], this simple tool takes a given markdown file and spits out a fairly impressive rendering — and you don’t even need to have one of those fancy new GPU-accelerated terminals. Most impressively, the whole thing is implemented as a single Bash script.

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3D Printing A Bottle Labeling Assembly Line

June 16, 2024 by 11 Comments

We’re not completely sure why [Fraens] needs to label so many glass bottles at home. Perhaps he’s brewing his own beer, or making jams. Whatever the reason is, it was justification enough to build an absolutely incredible labeling machine that you could mistake for a piece of industrial gear…if it wasn’t for the fact that majority of the device is constructed out of orange 3D printed plastic.

As we’ve come to expect, [Fraens] has documented the build with a detailed write-up on his site — but in this case, you’ve really got to watch the video below to truly appreciate how intricate the operation of this machine is. Watching it reminded us of an episode of How It’s Made, with the added bonus that you not only get to see how the machine functions, but how it was built in the first place.

Nearly every part of the machine, outside the fasteners, smooth rods, a couple of acrylic panels, and a few sections of aluminum extrusion, were 3D printed. You might think this would result in a wobbly machine with sloppy tolerances, but [Fraens] is truly a master of knowing when and where you can get away with using printed parts. So for example, while the glue rollers could be done in printed plastic, they still needed metal rods run through the middle for strength and proper bearings to rotate on.

Looking at the totality of this build, it’s hard to imagine how it could have been accomplished via traditional methods. Sure you could have sourced the rollers and gears from a supplier to save some plastic (at an added expense, no doubt), but there’s so many unique components that simply needed to be fabricated. For example, all the guides that keep the label heading in the right direction through the mechanism, or the interchangeable collars which let you select the pattern of glue which is to be applied. Maybe if you had a whole machine shop at your disposal, but that’s a lot more expensive and complex a proposition than the pair of desktop 3D printers [Fraens] used to crank out this masterpiece.

If the name (and penchant for orange plastic) seems familiar, it’s because we’ve featured several builds from [Fraens] in the past. This one may be the most technically impressive so far, but that doesn’t diminish the brilliance of his vibratory rock tumbler or cigarette stuffing machine.

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