Cheap 10x10cm Hotplate Punches Above Its Weight

December 10, 2025 by Arya Voronova 11 Comments

For less than $30 USD, you can get a 10×10 centimeter hotplate with 350 Watts of power. Sounds mighty fine to us, so surely there must be a catch? Maybe not, as [Stefan Nikolaj]’s review of this AliExpress hotplate details, it seems to be just fine enough.

At this price, you’d expect some shoddy electronics inside, or maybe outright fiery design decisions, in the vein of other reviews for similar cheap heat-producing tech that we’ve seen over the years. Nope – the control circuitry seems to be more than well-built for our standards, with isolation and separation where it matters, the input being fused away, and the chassis firmly earthed. [Stefan] highlights just two possible problem areas: a wire nut that could potentially be dodgy, and lack of a thermal fuse. Both can be remedied easily enough after you get one of these, and for the price, it’s a no-brainer. Apart from the review, there’s also general usage recommendations from [Stefan] in the end of the blog post.

While we’re happy to see folks designing their own PCB hotplates or modifying old waffle irons, the availability of cheap turn-key options like this means there’s less of a reason to go the DIY route. Now, if you’re in the market for even more build volume, you can get one of the classic reflow ovens, and maybe do a controller upgrade while you’re at it.

Ask Hackaday: Solutions, Or Distractions?

December 10, 2025 by Dan Maloney 12 Comments

The “Long Dark” is upon us, at least for those who live north of the equator, and while it’s all pre-holiday bustle, pretty lights, and the magical first snow of the season now, soon the harsh reality of slushy feet, filthy cars, and not seeing the sun for weeks on end will set in. And when it does, it pays to have something to occupy idle mind and hands alike, a project that’s complicated enough to make completing even part of it feel like an accomplishment.

But this time of year, when daylight lasts barely as long as a good night’s sleep, you’ve got to pick your projects carefully, lest your winter project remain incomplete when the weather finally warms and thoughts turn to other matters. For me, at least, that means being realistic about inevitabilities such as competition from the day job, family stuff, and the dreaded “scope creep.”

It’s that last one that I’m particularly concerned with this year, because it has the greatest potential to delay this project into spring or even — forbid it! — summer. And that means I need to be on the ball about what the project actually is, and to avoid the temptation to fall into any rabbit holes that, while potentially interesting and perhaps even profitable, will only make it harder to get things done.

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Failed 3D Printed Part Brings Down Small Plane

December 10, 2025 by Donald Papp 73 Comments

Back in March, a small aircraft in the UK lost engine power while coming in for a landing and crashed. The aircraft was a total loss, but thankfully, the pilot suffered only minor injuries. According to the recently released report by the Air Accidents Investigation Branch, we now know a failed 3D printed part is to blame.

The part in question is a plastic air induction elbow — a curved duct that forms part of the engine’s air intake system. The collapsed part you see in the image above had an air filter attached to its front (towards the left in the image), which had detached and fallen off. Heat from the engine caused the part to soften and collapse, which in turn greatly reduced intake airflow, and therefore available power.

Serious injury was avoided, but the aircraft was destroyed.

While the cause of the incident is evident enough, there are still some unknowns regarding the part itself. The fact that it was 3D printed isn’t an issue. Additive manufacturing is used effectively in the aviation industry all the time, and it seems the owner of the aircraft purchased the part at an airshow in the USA with no reason to believe anything was awry. So what happened?

The part in question is normally made from laminated fiberglass and epoxy, with a glass transition of 84° C. Glass transition is the temperature at which a material begins to soften, and is usually far below the material’s actual melting point.

When a part is heated at or beyond its glass transition, it doesn’t melt but is no longer “solid” in the normal sense, and may not even be able to support its own weight. It’s the reason some folks pack parts in powdered salt to support them before annealing.

The printed part the owner purchased and installed was understood to be made from CF-ABS, or ABS with carbon fiber. ABS has a glass transition of around 100° C, which should have been plenty for this application. However, the investigation tested two samples taken from the failed part and measured the glass temperature at 52.8°C and 54.0°C, respectively. That’s a far cry from what was expected, and led to part failure from the heat of the engine.

The actual composition of the part in question has not been confirmed, but it sure seems likely that whatever it was made from, it wasn’t ABS. The Light Aircraft Association (LAA) plans to circulate an alert to inspectors regarding 3D printed parts, and the possibility they aren’t made from what they claim to be.

A Musically-Reactive LED Christmas Tree

December 10, 2025 by Lewin Day 6 Comments

Regular Christmas trees don’t emit light, nor do they react to music. If you want both things in a holiday decoration, consider this build from [dbmaking].

An ESP32-D1 mini runs the show here. It’s hooked up to a strip of WS2812B addressable LEDs. The LED strip is placed on a wooden frame resembling the shape of a traditional Christmas tree. Ping-pong balls are then stacked inside the wooden frame such that they act as a light diffuser for the LEDs behind. The microcontroller is also hooked up to an INMP441 omnidirectional MEMS microphone module. This allows the ESP32 to detect sound and flash the LEDs in time, creating a colorful display that reacts to music. This is achieved by using the WLED web installer to set the display up in a sound reactive mode.

It’s a fun build, and we’d love to tinker around with coding more advanced visualizer effects for a build like this. We’ve seen builds that go the other way, too, by toning down excessive blinkiness in Christmas decorations.

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Putting KDE On Raspberry Pi OS Simpler Than Expected

December 9, 2025 by Arya Voronova 20 Comments

Raspberry Pi boards are no longer constrained – these days, you can get a quad-core board with 8 or 16GB of RAM to go around, equip it with a heatsink, and get a decently comfortable shop/desk/kitchen computer with GPIOs, cameras, speedy networking, maybe even NVMe, and all the wireless you’d expect.

Raspberry OS, however, remains lightweight with its pre-installed LXDE environment – and, in many cases, it feels quite constrained. In case you ever idly wondered about giving your speedy Pi a better UI, [Luc]/[lucstechblog] wants to remind you that setting up KDE on your Raspberry OS install is dead simple and requires only about a dozen commandline steps.

[Luc] walks you through these dozen steps, from installation to switching the default DE, and the few hangups you might expect after the switch; if you want to free up some disk space afterwards, [Luc] shows how to get rid of the original LXDE packages. Got the latest Trixie-based Pi OS? There’s an update post detailing the few necessary changes, as well as talking about others’ experiences with the switch.

All in all, [Luc] demonstrates that KDE will have a fair bit of graphical and UX advantages, while operating only a little slower, and if you weren’t really using your powerful Pi to the fullest, it’s a worthwhile visual and usability upgrade. For the regular desktop users, KDE has recently released their own distro, and our own [Jenny] has taken a look at it.

MagQuest: Measuring Earth’s Magnetic Field With Space-Based Quantum Sensors

December 9, 2025 by Maya Posch 5 Comments

Recently the MagQuest competition on improving the measuring of the Earth’s magnetic field announced that the contestants in the final phase have now moved on to launching their satellites within the near future. The goal here is to create a much improved World Magnetic Model (WMM), which is used by the World Geodetic System (WGS). The WGS is an integral part of cartography, geodesy and satellite-based navigation, which includes every sat nav, smartphone and similar with built-in GNSS capabilities.

Although in this age of sat navs and similar it can seem quaint to see anyone bother with using the Earth’s magnetic field with a compass, there is a very good reason why e.g. your Android smartphone has an API for estimating the Earth’s magnetic field at the current location. After your sat nav or smartphone uses its magnetometer, the measurements are then corrected so that ‘north’ really is ‘north’. Since this uses the WMM, it’s pertinent that this model is kept as up to date as possible, with serious shifts in 2019 necessitating an early update outside of the usual five-year cycle.

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Making Glasses That Detect Smartglasses

December 9, 2025 by Donald Papp 11 Comments

[NullPxl]’s Ban-Rays concept is a wearable that detects when one is in the presence of camera-bearing smartglasses, such as Meta’s line of Ray-Bans. A project in progress, it’s currently focused on how to reliably perform detection without resorting to using a camera itself. Right now, it plays a well-known audio cue whenever it gets a hit.

Currently, [NullPxl] is exploring two main methods of detection. The first takes advantage of the fact that image sensors in cameras act as tiny reflectors for IR. That means camera-toting smartglasses have an identifying feature, which can be sensed and measured. You can see a sample such reflection in the header image, up above.

As mentioned, Ban-Rays eschews the idea of using a camera to perform this. [NullPxl] understandably feels that putting a camera on glasses in order to detect glasses with cameras doesn’t hold much water, conceptually.

The alternate approach is to project IR in a variety of wavelengths while sensing reflections with a photodiode. Initial tests show that scanning a pair of Meta smartglasses in this way does indeed look different from regular eyeglasses, but probably not enough to be conclusive on its own at the moment. That brings us to the second method being used: wireless activity.

Characterizing a device by its wireless activity turned out to be trickier than expected. At first, [NullPxl] aimed to simply watch for BLE (Bluetooth Low-Energy) advertisements coming from smartglasses, but these only seem to happen during pairing and power-up, and sometimes when the glasses are removed from the storage case. Clearly a bit more is going to be needed, but since these devices rely heavily on wireless communications there might yet be some way to actively query or otherwise characterize their activity.

This kind of project is something that is getting some interest. Here’s another smartglasses detector that seems to depend entirely on sniffing OUIs (Organizationally Unique Identifiers); an approach [NullPxl] suspects isn’t scalable due to address randomization in BLE. Clearly, a reliable approach is still in the works.

The increasing numbers of smartglasses raises questions about the impact of normalizing tech companies turning people into always-on recording devices. Of course, the average person is already being subtly recorded by a staggering number of hidden cameras. But at least it’s fairly obvious when an individual is recording you with a personal device like their phone. That may not be the case for much longer.