TechyMagThings

Solid state batteries, we are told, are the new hot battery technology that will replace lithium-ion batteries. Soon. Not that we haven’t heard that before. One reason it isn’t dominating the market today is that it’s prone to short circuits during charging. [Dr. Yuwei Zhang and others have published a paper detailing why the shorts happen, which could lead to strategies to improve the technology.

Solid state batteries employ a solid electrolyte and a lithium anode. It is known that, sometimes, lithium metal from the anode forms dendrites that penetrate the ceramic electrolyte and cause it to crack. This is somewhat of a mystery as the lithium is a soft metal (to quote [Zhang], “like a gummy bear.”).

There were two leading hypotheses for the observations. [Zhang’s] team showed that hydrostatic stress made the lithium dendrites act like a water jet, enabling them to penetrate the hard ceramic.

There is still work to figure out what to do about it, but understanding the root cause is certainly a step in the right direction. We’ve looked at these batteries before. We’ve also seen how changing the anode construction might help with the problem.

Ultrasonic levitation is by now a familiar trick: one or more ultrasonic transducers create a standing wave, and small objects can be held in the nodes of this standing wave. With a sufficiently large array of transducers, it’s even possible to control the movement of the object. This isn’t the only form of ultrasonic levitation, however, as [Steve Mould] demonstrated with his ultrasonic air hockey table.

This less familiar form of levitation was discovered by [Bob Collins] while working on torpedo guidance systems: when he tried to place a glass lens on an ultrasonic transducer it immediately slid off. He found during further experimentation that an ultrasonic transducer would levitate over any sufficiently flat and smooth surface. It works by trapping a very thin layer of air between the transducer and the smooth surface. When the transducer moves sharply toward the surface, it compresses a layer of air in between, and forces some air out, and the reverse happens while pulling back. However, during the downstroke, the gap through which air can escape is narrower than during the upstroke, and there is more surface-induced drag, meaning that the inflow and outflow of air through a narrow gap isn’t completely equal. At a certain distance, inflow and outflow balance, and the transducer floats on a thin layer of air.

In [Steve]’s air hockey arena, the floor oscillates and the pucks levitate over this. Driving it using just one transducer didn’t work, since the floor formed standing waves, and the pucks would get stuck on node lines. Instead, he used two transducers, one at each end of the arena, and drove them out of phase with each other. This created a standing wave and minimized dead spots.

The arena was a bit small (having to be played using toothpicks), but it seemed to work well. If you prefer your air hockey a bit more human-scaled, we’ve seen a table build before. We’ve also seen ultrasonic levitation before, ranging from simple electronics kits to the driving force behind a full volumetric display or photography station.

Springs are great, but making them out of plastic tends to come with some downsides, for fairly obvious reasons. Creating a compliant mechanism that can be 3D printed and yet which doesn’t permanently deform or wear out after a few uses is therefore a bit of a struggle. The complaint toggle mechanism that [neotoy] designed is said to have addressed those issues, with the model available on Printables for anyone to give a shake.

The model in question is a toggle, which is the commonly seen plastic or metal device that clamps down on e.g. rope or cord and requires you to push on it to have it release said clamping force. Normally these use a metal spring inside, but this version is fully 3D printable and thus forms a practical way to test this particular compliant mechanism with a variety of materials.

The internal spring is a printed spiral spring, with the example in the video printed in PETG. You can of course also print it in other materials for different durability and springiness properties. As noted in the video, PLA makes for a very poor spring material, so you probably want to skip that one.

We covered compliant mechanisms in the past for purposes like blasters, including some that you can only see under a microscope.

When building a project to operate on battery power for long periods of time, having a microcontroller with a reliable and extremely low-power sleep mode is critical. When processing power isn’t needed, it should be able to wait around using almost no energy until an interrupt triggers it. Once triggered, the CPU performs its tasks and then puts itself right back to sleep, making sure the battery lasts as long as possible. Unfortunately, not every microcontroller has sleep capabilities or has an acceptably low level of power use for maximizing battery life. For these systems, a tool like this power manager might come in handy.

The small PCB, called the powerTimer, essentially acts as a middleman for power delivery to another microcontroller. On the PCB is an RV3028-C7 real-time clock, which uses a mere 45 nA of current and can interact with the second microcontroller through a timer or alarm. When commanded, the powerTimer uses an SR latch as its main control circuit, allowing single button presses to change the power state for the second microcontroller. Once the powerTimer powers up the second microcontroller, that microcontroller can communicate back to the powerTimer with a “DONE” signal, and once this signal is received, the powerTimer will cut power and wait for the next interrupt to occur.

The project’s creator, [Juan], had this idea for an ESP32 with a camera module.  While it does have a sleep mode, the ESP32 wasn’t nearly low-power enough to get the battery life that he wanted. With a modular system like this, it can be used in many other applications as well. PowerTimer is one of the entries in our 2026 Green Powered Challenge.

“Lights, camera, action!” might have been the call when recording back in the day, but for an awesome three-dimensional viewing experience, you might try yelling “Mist, Mirrors, Laser!” and following in the footsteps of [Ancient]’s latest adventure in voxel displays, which is also embedded below.

He starts with a naive demonstration: take a laser projector and toss an image into a flat cloud of mist. That demonstrates that yes, the mist does resolve an image, and that the viewing angle is very poor– that is, brightness drops off sharply when you’re out of line from the projector. In this case, that’s a good thing! It means more angles can be projected into that mist for a three-dimensional, hologram effect.

The optical train gets folded up, probably to make this fit on a tabletop: first, an array of flat mirrors in front of the projector splits the image from the projector into multiple viewpoints, which are each bounced to a second flat mirror that sends the image into the fog bank.

Some might call the resulting image a hologram; others might complain that that’s technically something totally different, and that this volumetric display is just all smoke and mirrors. We can hope that [Ancient] sees fit to share more details, like the software stack needed to generate the video feed– though it’s likely using a version of the same software as his last volumetric display, which used the same laser but whose point cloud was made from a bubblegram rather than an actual cloud. With a lot more points, though, the resolution is amazing in comparison, at the cost of appearing fuzzy at the edges. Unfortunately, we do not see the display in this demo run DOOM, as one of his previous projects did.

This video is more of a demo than a how-to, but it’s a heck of an impressive demo. If you don’t feel like watching the assembly, jump right to 9:00 to be impressed. It comes across a lot better on video than in the screenshot.

It’s been three weeks since the Artemis II crew returned to Earth, and while the mission might be over for Reid Wiseman, Victor Glover, Christina Hammock Koch, and Jeremy Hansen, the work is only just beginning for engineers back at NASA. In a blog post earlier this week, the space agency went over the preliminary post-mission assessments of the spacecraft and its ground support equipment, and detailed some of the work that’s currently taking place as preparations begin for Artemis III.

During Artemis I, higher than expected damage was noted on both the Orion’s heat shield and the Space Launch System (SLS) launch pad. But according to NASA, the changes implemented after that first mission seem to have prevented similar issues this time around. The post also explains that reusable components of the Orion spacecraft, such as the avionics and the crew seats, are already in the process of being removed from Integrity so they can be installed in the next capsule on the production line.

While watching the live stream of the Artemis mission is the closest most of us will ever get to experiencing spaceflight, that doesn’t mean you can’t explore the solar system from the comfort of your own home — or more specifically, your browser. [Sani Huttunen] has created an incredible web-based solar system simulator that lets you explore our celestial neighborhood throughout different periods of time. You can tour the moons of Jupiter, see how the planets aligned on the date of your birth, and even check in on the Voyager probes. There are some very valid reasons to be skeptical about software moving to the web, but we’ve got to admit, this is a very slick demonstration of just how far modern browsers have come.

Speaking of how far things have come, are you ready for a car without a rear window? Polestar certainly hopes so, as their latest model does away with such quaint concepts. The glass panel in the roof ends right around the back headrests, and while the rear of the vehicle does open up for storage, the hatch is completely solid. In place of the traditional mirror, there’s a “high resolution” 1480 x 320 display that shows the feed from a rear-mounted camera.

No, that’s not a typo. At a time when smartphones are shipping with 2K displays, should the driver want to see what’s going on behind their $70,000+ USD electric vehicle, they’re limited to seeing it at a vertical resolution below that of VGA. We’d make a joke about Polestar offering up a “Rearview+” upgrade down the line that would give the driver a higher resolution view, but honestly, it’s getting a little too close to reality to be funny.

If that last one has you wishing for a reminder of simpler times, how about some new software for using the iconic Wii Remote as an input device? The Wii and its revolutionary controllers may be turning 20 later this year, but that hasn’t stopped the dedicated fans. This new wrapper provides accelerometer calibration, infrared tracking, and the ability to remap the Wii Remote’s buttons and create key combos. If you do something cool with it, we’d love to hear about it.

Finally, on the other end of the input spectrum, some details leaked out this weekend about Valve’s upcoming Steam controller — namely, the fact that it will cost players $99 at release. As reported by VICE, a hands-on review of the controller by TechyTalk was accidentally published early on YouTube, providing the public with pricing info ahead of an official announcement.

At first blush, this might seem like a lot of money to pay for a game controller, but it’s actually within striking distance of the sticker price on the standard controllers on the Xbox and PlayStation consoles. Perhaps more critically, it’s around half the price of the official “premium” controller offerings available for the aforementioned systems. Is it really any wonder that we’ve got cars without rearview mirrors when folks are putting down 200 bucks for a fancy PlayStation controller?

See something interesting that you think would be a good fit for our weekly Links column? Drop us a line, we’d love to hear about it.

For those first venturing into sailing, it can be overwhelming since the experience is thick with jargon and skills that don’t often show up in life ashore. With endless choices, including monohulls versus catamarans, fiberglass versus wood, fractional versus masthead rigs, and sloops versus ketches, a new sailor risks doing something like single-handing a staysail schooner when they should have started on a Bermuda-rigged dinghy without a spinnaker. Luckily, there are some shortcuts to picking up the hobby, like the venerable Sunfish or Hobie ships. It’s also possible to build a simple sailing vessel completely out of materials from a local hardware store, as [Cumberland Rover] has been demonstrating.

[Cumberland Rover] has a number of homemade vessels under his belt, from various kayaks and rowboats. His latest project is a 12-foot rowboat, which has the option to add a mast and sail. The hull is made from two 1×12 pieces of lumber, bent around a frame and secured. Plywood makes the bottom, and a few seats finish out the build. He’s also using standard hardware to fasten everything together, which helps with maintenance. It came in handy when he recently added some height to the bow of the boat to improve seaworthiness.

For sailing, the mast is made out of two pieces of 2x lumber glued together and then worked into a more cylindrical shape. It’s unstayed, reducing complexity, and although he broke one in extremely high winds, it is more than strong enough for most of his sailing. The ship is gaff-rigged, with a square sail hoisted up the mast by a wooden spar. All of these design choices make it quick and easy to set the sail up when the wind is good or pack it away fast when it’s time to row.

Although there are paid plans available on his website, the methods used in the video show how simple it can be to get into rowing or sailing with a minimal cost. You’ll still want to learn the basics of sailing before taking one of these out into open water. DIY speedboats are also possible and accessible as well, but there’s the added complexity of a motor here to think about, as well as registration requirements that often accompany powered craft.