The Fascinating Waveguide Technology Inside Meta’s Ray-Ban Display Glasses

October 9, 2025 by Maya Posch 27 Comments

The geometric waveguide glass of the Meta Ray-Ban Display glasses. (Credit iFixit)

Recently the avid teardown folk over at iFixit got their paws on Meta’s Ray-Ban Display glasses, for a literal in-depth look at these smart glasses. Along the way they came across the fascinating geometric waveguide technology that makes the floating display feature work so well. There’s also an accompanying video of the entire teardown, for those who enjoy watching a metal box cutter get jammed into plastic.

Overall, these smart glasses can be considered to be somewhat repairable, as you can pry the arms open with a bit of heat. Inside you’ll find the 960 mWh battery and a handful of PCBs, but finding spare parts for anything beyond perhaps the battery will be a challenge. The front part of the glasses contain the antennae and the special lens on the right side that works with the liquid crystal on silicon (LCoS) projector to reflect the image back to your eye.

While LCoS has been used for many years already, including Google Glass, it’s the glass that provides the biggest technological advancement. Instead of the typical diffractive waveguide it uses a geometric reflective waveguide made by Schott, with the technology developed by Lumus for use in augmented reality (AR) applications. This is supposed to offer better optical efficiency, as well as less light leakage into or out of the waveguide.

Although definitely impressive technology, the overall repairability score of these smart glasses is pretty low, and you have to contest with both looking incredibly dorky and some people considering you to be a bit of a glasshole.

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Why Stepper Motors Still Dominate 3D Printing

October 8, 2025 by Maya Posch 43 Comments

It’s little secret that stepper motors are everywhere in FDM 3D printers, but there’s no real reason why you cannot take another type of DC motor like a brushless DC (BLDC) motor and use that instead. Interestingly, some printer manufacturers are now using BLDCs for places where the reduction in weight matters, such as in the tool head or extruder, but if a BLDC can be ‘stepped’ much like any stepper motor, then why prefer one over the other? This is the topic of a recent video by [Thomas Sanladerer], with the answer being mostly about cost, and ‘good enough’ solutions.

The referenced driving method of field-oriented control (FOC), which also goes by the name of vector control, is a VFD control method in which the controller can fairly precisely keep position much like a stepper motor, but without the relatively complex construction of a stepper motor. Another advantage is that FOC tends to use less power than alternatives.

Using a FOC controller with a BLDC is demonstrated in the video, which also covers the closed-loop nature of such a configuration, whereas a stepper motor is generally driven in an open-loop fashion. Ultimately the answer at this point is that while stepper motors are ‘good enough’ for tasks where their relatively large size and weight aren’t real issues, as BLDCs with FOC or similar becomes more economical, we may see things change there.

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Building The DVD Logo Screensaver With LEGO

October 8, 2025 by Maya Posch 9 Comments

The completed Lego DVD screensaver. (Credit: Grant Davis, YouTube)

There’s something extremely calming and pleasing about watching a screensaver that merely bounces some kind of image around, with the DVD logo screensaver of a DVD player being a good example. The logical conclusion is thus that it would be great to replicate this screensaver in Lego, because it’d be fun and easy. That’s where [Grant Davis]’s life got flipped upside-down, as this turned out to be anything but an easy task in his chosen medium.

Things got off on a rocky start with figuring out how to make the logo bounce against the side of the ‘screen’, instead of having it merely approach before backing off. The right approach here seemed to be Lego treads as used on e.g. excavators, which give the motion that nice pause before ‘bouncing’ back in the other direction.

With that seemingly solved, most of the effort went into assembling a functional yet sturdy frame, all driven by a single Lego Technic electromotor. Along the way there were many cases of rapid self-disassembly, ultimately leading to a complete redesign using worm gears, thus requiring running the gears both ways with help from a gearbox.

Since the screensaver is supposed to run unattended, many end-stop and toggle mechanisms were tried and discarded before settling on the design that would be used for the full-sized build. Naturally, scaling up always goes smoothly, so everything got redesigned and beefed up once again, with more motors added and multiple gearbox design changes attempted after some unfortunate shredded gears.

Ultimately [Grant] got what he set out to do: the DVD logo bouncing around on a Lego ‘TV’ in a very realistic fashion, set to the noise of Lego Technic gears and motors whirring away in the background.

Thanks to [Carl Foxmarten] for the tip.

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Building A Diwheel To Add More Tank Controls To Your Commute

October 7, 2025 by Maya Posch 19 Comments

It’s often said that one should not reinvent the wheel, but that doesn’t mean that you cannot change how the use of said wheel should be interpreted. After initially taking the rather zany concept of a monowheel for a literal ride, [Sam Barker] decided to shift gears, did a ‘what if’ and slapped a second monowheel next to the first one to create his diwheel vehicle. Using much thicker steel for the wheels and overall much more robust construction than for his monowheel, the welding could commence.

It should be said here that the concept of a diwheel, or dicycle, isn’t entirely new, but the monowheel – distinct from a unicycle – is much older, with known builds at least as far back as the 19th century. Confusing, self-balancing platforms like Segways are also referred to as ‘dicycles’, while a diwheel seems to refer specifically to what [Sam] built here. That said, diwheels are naturally stable even without gyroscopic action, which is definitely a big advantage.

The inner frame for [Sam]’s diwheel is built out of steel too, making it both very robust and very heavy. High-tech features include suspension for that smooth ride, and SLS 3D-printed nylon rollers between the inner frame and the wheels. After some mucking about with a DIY ‘lathe’ to work around some measurement errors, a lot more welding and some questionable assembly practices, everything came together in the end.

This is just phase one, however, as [Sam] will not be installing pedals like it’s an old-school monowheel. Instead it’ll have electrical drive, which should make it a bit less terrifying than the Ford Ka-based diwheel we featured in 2018, but rather close to the electric diwheel called EDWARD which we featured back in 2011. We hope to see part two of this build soon, in which [Sam] will hopefully take this beast for its first ride.

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Qualcomm Introduces The Arduino Uno Q Linux-Capable SBC

October 7, 2025 by Maya Posch 89 Comments

Generally people equate the Arduino hardware platforms with MCU-centric options that are great for things like low-powered embedded computing, but less for running desktop operating systems. This looks about to change with the Arduino Uno Q, which keeps the familiar Uno formfactor, but features both a single-core Cortex-M33 STM32U575 MCU and a quad-core Cortex-A53 Qualcomm Dragonwing QRB2210 SoC.

According to the store page the board will ship starting October 24, with the price being $44 USD. This gets you a board with the aforementioned SoC and MCU, as well as 2 GB of LPDDR4 and 16 GB of eMMC. There’s also a WiFi and Bluetooth module present, which can be used with whatever OS you decide to install on the Qualcomm SoC.

This new product comes right on the heels of Arduino being acquired by Qualcomm. Whether the Uno Q is a worthy purchase mostly depends on what you intend to use the board for, with the SoC’s I/O going via a single USB-C connector which is also used for its power supply. This means that a USB-C expansion hub is basically required if you want to have video output, additional USB connectors, etc. If you wish to run a headless OS install this would of course be much less of a concern.

Google Confirms Non-ADB APK Installs Will Require Developer Registration

October 6, 2025 by Maya Posch 162 Comments

After the news cycle recently exploded with the announcement that Google would require every single Android app to be from a registered and verified developer, while killing third-party app stores and sideloading in the process, Google has now tried to put out some of the fires with a new Q&A blog post and a video discussion (also embedded below).

When we first covered the news, all that was known for certain was the schedule, with the first trials beginning in October of 2025 before a larger rollout the next year. One of the main questions pertained to installing apps from sources that are not the Google Play Store. The answer here is that the only way to install an app without requiring one to go through the developer verification process is by installing the app with the Android Debug Bridge, or adb for short.

The upcoming major release of Android 16 will feature a new process called the Android Developer Verifier, which will maintain a local cache of popular verified apps. The remaining ones will require a call back to the Google mothership where the full database will be maintained. In order to be a verified Android developer you must have a Google Play account, pay the $25 fee and send Google a scan of your government-provided ID. This doesn’t mean that you cannot also distribute your app also via F-Droid, it does however mean that you need to be a registered Play Store developer, negating many of the benefits of those third-party app stores.

Although Google states that they will also introduce a ‘free developer account type’, this will only allow your app to be installed on a limited number of devices, without providing an exact number so far. Effectively this would leave having users install unsigned APKs via the adb tool as the sole way to circumvent the new system once it is fully rolled out by 2027. On an unrelated note, Google’s blog post also is soliciting feedback from the public on these changes.

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Logitech POP Buttons Are About To Go Pop

October 6, 2025 by Maya Posch 70 Comments

For those who missed out on the past few years of ‘smart home’ gadgets, the Logitech POP buttons were introduced in 2018 as a way to control smart home devices using these buttons and a central hub. After a few years of Logitech gradually turning off features on this $100+ system, it seems that Logitech will turn off the lights in two weeks from now. Remaining POP Button users are getting emails from Logitech in which they are informed of the shutdown on October 15 of 2025, along with a 15% off coupon code for the Logitech store.

Along with this coupon code only being usable for US-based customers, this move appears to disable the hub and with it any interactions with smart home systems like Apple HomeKit, Sonos, IFTTT and Philips Hue. If Logitech’s claim in the email that the buttons and connected hub will ‘lose all functionality’, then it’d shatter the hopes for those who had hoped to keep using these buttons in a local fashion.

Suffice it to say that this is a sudden and rather customer-hostile move by Logitech. Whether the hub can be made to work in a local fashion remains to be seen. At first glance there don’t seem to be any options for this, and it’s rather frustrating that Logitech doesn’t seem to be interested in the goodwill that it would generate to enable this option.