Mysterious Files PH

There’s a meme which may have a basis in truth, of a teenager left clueless when presented with a rotary telephone. The dial, in reality a mechanical pulse chain generator, was once ubiquitous enough that having one in your parts bin was anything but unusual. If you’re curious about their inner workings in 2026 though, you may be out of luck. Never fear though, because [Moeya 3D Designs] is here with a fully 3D printed version. It’s not as compact as the original, but it’s all there.

If you’re not put off by the anime-style Japanese voice over on the video below the break and you can enable subtitles for your language, you get the full explanation. There’s a ratchet and spring on the dial, which when released drives a gear train that ends in a cam that would operate a switch for the pulses. Another set of gears drives a very neatly designed centrifugal speed governor, and we see the effect immediately when it is removed. We’re not sure who will go for this project, but we surely like it.

There are two videos below the break, with the dial shown off in the first and the design process in the second. Meanwhile we’ve talked in the past about the networks behind the dials.

Thanks [Jan] for the tip.

Sunday night, around 7:00 PM local time, a bright fireball streaked across the western German sky, exploded, and rained chunks of space rock down on the region around Koblenz. One of the largest known chunks put a soccer-ball-sized hole in someone’s roof, landing in their bedroom. Fortunately, nobody was hurt. But given the apparent size of the explosion, there must be many more pieces out there for the finding, and a wave of hopeful meteorite hunters has descended upon the region.

But if you wanted a piece of the action, where exactly would you start looking? How do scientists find meteorites anyway? And what should you do if you happen to see a similar fireball in the night sky?

Citizen Science

In the age of always-on dashboard cameras, ubiquitous smartphones, and other video recording devices, it’s hard for a shy meteorite to find a quiet spot out of the public eye. That makes them a lot easier to find than they were in the past. Indeed, the International Meteor Organization, which aggregates amateur meteor observations, received more than 3,200 reports of this one, including several with video documentation. Some are stunning, and others may not even be of the event at all.

By collecting reports from many locations, they can hope to piece together the meteorite’s trajectory. However, if you look at the individual reports, it’s clear that this is a difficult task. Nobody is expecting a bright fireball to streak across the night sky, so many of the reports are reasonably vague on the details and heavy on the awe.

This report from [Sophie Z], for instance, is typical. She records where she was and roughly the location in the night sky where the meteorite passed, along with the comment “I’ve never seen anything so amazing and large before in my life.” Other amateur observers are more precise. [David C] (“I have a Ph.D in physics”) managed to record the start and the end heading of the meteorite to a couple of decimal places. He must have had a camera.

We’d love to know the exact algorithm used for combining the reports. It’s worth noting that reporters get an experience score, and the system presumably takes this into account when producing the average track. However, the system works, though, with 3,200 reports of a once-in-a-lifetime meteorite, it’s bound to come up with a pretty good estimate. But for smaller meteorites, like this one that flew by on Monday night, there are fewer observers, and deducing the actual track is a lot more difficult.

Everyday meteorites are better tracked by taking a more systematic approach. We’ve covered a few of these networks before, because the equipment needed to contribute meaningfully isn’t all that much more complicated than a single-board computer with a network connection, a camera module, and a weatherproof housing to keep it working all year round. We’ve covered the French meteorite-hunting network, Fripon, before, and have featured other amateur sky-camera builds to boot. But we’re not amateur astronomers, so we’re not in the loop on what the current state of the art is. If you know about coordinated citizen-science meteorite tracking efforts, let us know in the comments.

Geologists Get Into The Astronomy Game

This meteorite was big enough and loud enough when it exploded that participation in tracking wasn’t limited to those who are looking up. Geologists at the Karlsruhe Institute for Technology (KIT) found that the explosion registered on their seismometers. (Via Heise Online.) These have the advantage that they are in very well-known locations with extremely precise timestamps. After all, that’s what they’re used for every day, although the medium that the pressure waves travel through is usually the earth rather than the air.

This was also a particularly lucky event for the KIT team because it happened over a particularly dense network of seismological stations in the Eifel mountains, allowing for greater resolution. And as they point out, using the sound of the explosion has the additional advantage of not being hindered by light conditions during the day or clouds at night. This makes us think of how easy it would be to set up a distributed system of microphones to do something similar.

The KIT track estimate lines up fairly well with the aggregated estimate from amateur observers, but it’s not exactly the same. Who is right? We’ll see where more of the meteorites are found on the ground, presumably, in the next few weeks.

Meteorite Hunting

If the meteorite fell through our roof and chunks were scattered all around our bedroom, we’d count ourselves lucky. But would we get to keep it? Of course, it depends on the local laws, and in Germany, you can keep the meteorites in most cases, unless the state decides that it’s of special value for whatever reason, and then they get first dibs.

Apparently, the going rate for meteorites is between 1€ and 5,000€ per gram, so we’re not entirely sure that it will cover the damage. Maybe our homeowners’ insurance would? We’ll have to go dig out our policy to be sure, but however that plays out, we’d just be stoked to have the meteorite chunks and a good story.

While very big fireballs like this are rare, NASA estimates that around 44,000 kg of meteoritic material falls on the Earth every day. (Whoah!) Most of this burns up in the atmosphere, but some falls to the ground. Most of that fraction is in the form of micrometeorites, which are sand-grain-sized bits that are very likely raining down on us every day. Indeed, if you’re interested, you can try to collect them, and all you need is a tarp on the roof or a magnet in your downspout, a good microscope, and a bit of knowledge. So if all you want is some extraterrestrial rock, and you’re not worried so much about the size, maybe micrometeorite hunting is the path to success.

Have you gone looking for meteorites? Know of any up-to-date amateur fireball-hunting networks? Sound off in the comments!

This unusual clock by [Moritz v. Sivers] looks like a holographic dial surrounded by an LED ring, but that turns out to not be the case. What appears to be a ring of LEDs is in fact a second hologram. There are LEDs but they are tucked out of the way, and not directly visible. The result is a very unusual clock that really isn’t what it appears to be.

The face of the clock is a reflection hologram of a numbered spiral that serves as a dial. A single LED – the only one visibly mounted – illuminates this hologram from the front in order to produce the sort of holographic image most of us are familiar with, creating a sense of depth.

The lights around the circumference are another matter. What looks like a ring of LEDs serving as clock hands is actually a transmission hologram made of sixty separate exposures. By illuminating this hologram at just the right angle with LEDs (which are mounted behind the visible area), it is possible to selectively address each of those sixty exposures. The result is something that really looks like there are lit LEDs where there are in fact none.

[Moritz] actually made two clocks in this fashion. The larger green one shown here, and a smaller red version which makes some of the operating principles a bit more obvious on account of its simpler construction.

If it all sounds a bit wild or you would like to see it in action, check out the video (embedded below) which not only showcases the entire operation and assembly but also demonstrates the depth of planning and careful execution that goes into multi-exposure of a holographic plate.

[Moritz v. Sivers] is no stranger to making unusual clocks. In fact, this analog holographic clock is a direct successor to his holographic 7-segment display clock. And don’t miss the caustic clock, nor his lenticular clock.

Debugging an application crash can oftentimes feel like you’re an intrepid detective in a grimy noir detective story, tasked with figuring out the sordid details behind an ugly crime. Slogging through scarce clues and vapid hints, you find yourself down in the dumps, contemplating the deeper meaning of life and  the true nature of man, before hitting that eureka moment and cracking the case. One might say that this makes for a good game idea, and [Jonathan] would agree with that notion, thus creating the Fatal Core Dump game.

Details can be found in the (spoiler-rich) blog post on how the game was conceived and implemented. The premise of the game is that of an inexplicable airlock failure on an asteroid mining station, with you being the engineer tasked to figure out whether it was ‘just a glitch’ or that something more sinister was afoot. Although an RPG-style game was also considered, ultimately that proved to be a massive challenge with RPG Maker, resulting in this more barebones game, making it arguably more realistic.

Suffice it to say that this game is not designed to be a cheap copy of real debugging, but the real deal. You’re expected to be very comfortable with C, GDB, core dump analysis, x86_64 ASM, Linux binary runtime details and more. At the end you should be able to tell whether it was just a silly mistake made by an under-caffeinated developer years prior, or a malicious attack that exploited or introduced some weakness in the code.

If you want to have a poke at the code behind the game, perhaps to feel inspired to make your own take on this genre, you can take a look at the GitHub project.

Alzheimer’s disease remains a frustratingly difficult condition to manage for the millions of patients affected worldwide and their families. The cause of the disease is still not properly understood, and by the time memory loss and cognitive decline become apparent, the underlying brain pathology has often been quietly building for decades.

Soon, though it may be possible to diagnose impending Alzheimer’s disease ahead of time, before symptoms have taken hold. New research suggests this could be achieved through a simple blood draw, providing clinicians and patients precious time to manage the condition and plan ahead.

Early Warning

A hallmark of Alzheimer’s disease is the buildup of amyloid and tau protein in the brain. Despite decades of research, the protein’s precise role in the disease remains somewhat unclear. Typically, Alzheimer’s disease is diagnosed by symptoms like memory loss and cognitive decline, with later investigation revealing the presence of elevated levels of these proteins in the brain. This investigation often involves brain imaging or invasive and painful spinal fluid tests.

However, researchers have developed a new predictive model that suggests it’s possible to estimate when a person will begin showing Alzheimer’s symptoms, based on a similar marker. The key ingredient is another protein called p-tau217, which circulates in the blood plasma and mirrors the slow, steady accumulation of amyloid and tau protein within the brain tissues.

Earlier research had previously established that p-tau217 levels tended to track alongside the rise of amyloid and tau buildup in the brain. This indicated that the level of p-tau217 in the blood could be a proxy for how far along the disease process has progressed. This allows the estimation of how many years remain before symptoms emerge for a given patient, with the research study suggesting this could be as specific as a margin of three or four years.

The research study drew on data from 603 older adults enrolled in two long-running studies — the Knight Alzheimer Disease Research Center at WashU Medicine and the multi-site Alzheimer’s Disease Neuroimaging Initiative. Plasma p-tau217 was measured using simple blood draws. One of the more interesting findings concerns age. The model revealed that the interval between elevated p-tau217 levels and symptom onset isn’t fixed. A person whose levels first ticked upwards at the age 60 might not develop noticeable cognitive problems for another two decades. But if that same elevation appeared at age 80, symptoms tended to follow within about eleven years. It suggests that younger brains appear to tolerate Alzheimer’s-related pathology for longer, while older brains are less able to withstand the protein buildup once the process gets underway.

Right now, p-tau217 testing is primarily used to help confirm an Alzheimer’s diagnosis in patients who are already experiencing cognitive trouble. It isn’t recommended for screening asymptomatic individuals outside of research settings. However, using p-tau217 as a predictive marker has obvious potential. If clinical trials for preventive Alzheimer’s drugs could enroll participants based on a predicted timeline for symptom onset, rather than waiting years for decline to actually happen, those trials could become dramatically shorter and cheaper to run, and  more efficient in general. Perhaps more importantly, it has the potential to give patients a better understanding of what lies ahead, allowing them to plan ahead before cognitive symptoms become an unmanageable imposition on their life.

The research team has made their model development code publicly available on Github and created a web-based tool that lets other researchers explore the clock models in detail. Looking ahead, they note that combining p-tau217 with other blood-based biomarkers linked to cognitive decline could sharpen predictions even further. It’s still early days, but a future where a routine blood test could serve as an early-warning system for Alzheimer’s is looking more plausible than it did a few years ago.

Who among us does not have a plethora of mains-powered devices on their workbench, and a consequent mess of power strips to run them all? [Jeroen Brinkman] made his more controllable with a multi-way switch box.

At first sight it’s a bank of toggle switches, one for each socket. But this is far more than a wiring job, because of course there are a couple of microcontrollers involved, and each of those switches ultimately controls a relay. There are also status LEDs for each socket, and a master switch to bring them all down. Arduino code is provided, so you can build one too if you want to.

We like the idea of a handy power strip controller, and especially the master switch with the inherent state memory provided by the switches. This could find a home on a Hackaday bench, and we suspect on many others too. It’s by no means the first power strip with brains we’ve seen, but most others have been aimed at the home instead.

What hardware hacker doesn’t have a soft spot for transparent cases? While they may have fallen out of mainstream favor, they have an undeniable appeal to anyone with an interest in electronic or mechanical devices. Which is why the Orbigator built by [wyojustin] stands out among similar desktop orbital trackers we’ve seen.

Conceptually, it’s very similar to the International Space Station tracking lamp that [Will Dana] built in 2025. In fact, [wyojustin] cites it specifically as one of the inspirations for this project. But unlike that build, which saw a small model of the ISS moving across the surface of the globe, a transparent globe is rotated around the internal mechanism. This not only looks gorgeous, but solves a key problem in [Will]’s design — that is, there’s no trailing servo wiring that needs to be kept track of.

For anyone who wants an Orbigator of their own, [wyojustin] has done a fantastic job of documenting the hardware and software aspects of the build, and all the relevant files are available in the project’s GitHub repository.

The 3D printable components have been created with OpenSCAD, the firmware responsible for calculating the current position of the ISS on the Raspberry Pi Pico 2 is written in MicroPython, and the PCB was designed in KiCad. Incidentally, we noticed that Hackaday alum [Anool Mahidharia] appears to have been lending a hand with the board design.

As much as we love these polished orbital trackers, we’ve seen far more approachable builds if you don’t need something so elaborate. If you’re more interested in keeping an eye out for planes and can get your hands on a pan-and-tilt security camera, it’s even easier.