Hackaday

Composting doesn’t seem difficult: pile up organic matter, let it rot. In practice, however, it’s a bit more complicated– if you want that sweet, sweet soil amendment in a reasonable amount of time, and to make sure any food-born pathogens and weed seeds don’t come through, you need a “hot” compost pile. How to tell if the pile is hot? Well, you could go out there and stick your arm in like a schmuck, or you could use [Dirk-WIllem van Gulik]’s “LORAWAN Compostheap solarpowered temperaturesensor” (sic).

The project is exactly what it sounds like, once you add some spaces: a solar-powered temperature sensor that uses LoRaWAN to track temperatures inside (and outside, for comparison) the compost heap year round. Electronically it is pretty simple: a Helltech CubeCell AB01 LoraWAN module is wired up with three DS18B20 temperature sensors, a LiPo battery and a solar panel. (The AB01 has the required circuitry to charge the battery via solar power.)

The three temperature sensors are spread out: within a handmade of a metal spike to measure the core of the heap, one partway up the metal tube holding said spike, to measure the edge of the pile, and one in the handsome 3D printed case to measure the ambient temperature. These three measurements, and the difference between them, should give a very good picture of the metabolism of the pile, and cue an observant gardener when it is time to turn it, water it, or declare it done.

Given it only wakes every hour or so for measurements (compost piles aren’t a fast moving system like an RMBK) and has a decent-sized panel, the LiPo battery isn’t going to see much stress and will likely last many years, especially in the benevolent Dutch climate. [Dirk] is also counting on that climate to keep the printed PLA enclosure intact. If one was to recreate this project for Southern California or North Australia, a different filament would certainly be needed, but the sun doesn’t beat down nearly as hard in Northern Europe and PLA will probably last at least as long as the battery.

Of course with this device it’s still up to the gardener to decide what to do with the temperature data and get out to do the hard work. For those who prefer more automation and less exercise, this composter might be of interest.

Our thanks to [Peter de Bruin] for the tip about this finely-turned temperature sensing tip. If you, too, want to bask in the immortal fame brought by a sentence of thanks at the end of a Hackaday article (or perhaps a whole article dedicated to your works?) submit a tip and your dreams may come true.

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Unlike computer games, which smoothly and continuously evolved along with the hardware that powered them, console games have up until very recently been constrained by a generational style of development. Sure there were games that appeared on multiple platforms, and eventually newer consoles would feature backwards compatibility that allowed them to play select titles from previous generations of hardware. But in many cases, some of the best games ever made were stuck on the console they were designed for.

Now, for those following along as this happened, it wasn’t such a big deal. For gamers, it was simply a given that their favorite games from the Super Nintendo Entertainment System (SNES) wouldn’t play on the Nintendo 64, any more than their Genesis games could run on their Sony PlayStation. As such, it wasn’t uncommon to see several game consoles clustered under the family TV. If you wanted to go back and play those older titles, all you had to do was switch video inputs.

But gaming, and indeed the entertainment world in general, has changed vastly over the last couple of decades. Telling somebody today that the only way they can experience The Legend of Zelda: A Link to the Past is by dragging out some yellowed thirty-odd year old console from the attic is like telling them the only way they can see a movie is by going to the theater.

These days, the expectation is that entertainment comes to you, not the other way around — and it’s an assumption that’s unlikely to change as technology marches on. Just like our TV shows and movies now appear on whatever device is convenient to us at the time, modern gamers don’t want to be limited to their consoles, they also want to play games on their phones and VR headsets.

But that leaves us with a bit of a problem. There are some games which are too significant, either technically or culturally, to just leave in the digital dust. Like any other form of art, there are pieces that deserve to be preserved for future generations to see and experience.

For the select few games that are deemed worth the effort, decompilation promises to offer a sort of digital immortality. As several recent projects have shown, breaking a game down to its original source code can allow it to adapt to new systems and technologies for as long as the community wishes to keep them updated.

Emulation For Most, But Not All

Before we get into the subject of decompilation, we must first address a concept that many readers are likely familiar with already: emulation.

Using a console emulator to play an old game is not entirely unlike running an operating system through a virtual machine, except in the case of the console emulator, there’s the added complication of having to replicate the unique hardware environment that a given game was designed to run on. Given a modern computer, this usually isn’t a problem when it comes to the early consoles. But as you work your way through the console generations, the computational power required to emulate their unique hardware architectures rapidly increases.

Nintendo put emulation to work with their “Mini” consoles.

The situation is often complicated by the fact that some games were painstakingly optimized for their respective console, often making use of little-documented quirks of the hardware. Emulators often employ title-specific routines to try and make these games playable, but they aren’t always 100% successful. Even on games that aren’t particularly taxing, the general rule of emulation is to put performance ahead of accuracy.

Therein lies the key problem with emulation when it comes to preserving games as an artistic medium. While the need for ever-more powerful hardware is a concern, Moore’s Law will keep that largely in check. The bigger issue is accuracy. Simply running a game is one thing, but to run it exactly how it was meant to run when the developers released it is another story entirely.

It’s fairly common for games to look, sound, and even play slightly differently when under emulation than they did when running on real hardware. In many cases, these issues are barely noticeable for the average player. The occasional sound effect playing out of sync, or a slightly shifted color palette isn’t enough to ruin the experience. Other issues, like missing textures or malfunctioning game logic can be bad enough that the game can’t be completed. There are even games, few as they may be, that simply don’t run at all under emulation.

Make no mistake, emulation is usually good enough for most games. Indeed, both Nintendo and Sony have used emulation in various capacities to help bring their extensive back catalog of games to newer generations. But the fact remains that there are some games which deserve, and sometimes even require, a more nuanced approach.

Chasing Perfection

In comparison, when a game is decompiled to the point that the community has the original C code that it was built from, it’s possible to avoid many of the issues that come with emulation. The game can be compiled as a native executable for modern platforms, and it can take advantage of all the hardware and software improvements that come with it. It’s even possible to fix long-standing bugs, and generally present the game in its best form.

For those who’ve dabbled in reverse engineering, you’ll know that decompiling a program back into usable C code isn’t exactly a walk in the park. While there are automated tools that can help get through a lot of the work, there’s still plenty of human intervention required. Even then, the original code for the game would have been written to take advantage of the original console’s unique hardware, so you’ll need to either patch your way around that or develop some kind of compatibility layer to map various calls over to something more modern and platform-agnostic. It’s a process that can easily take years to complete.

Because of this, decompilation efforts tend to be limited to the most critically acclaimed titles. For example, in 2021 we saw the first efforts to fully reverse The Legend of Zelda: Ocarina of Time. Released in 1998 on the N64, it’s often hailed as one of the greatest video games ever made. Although the effort started with Ocarina, by 2024, the lessons learned during that project led to the development of tools which can help decompile and reconstruct other N64 games.

Games as Living Documents

For the most part, an emulated game works the same way it did when it was first released. Of course, the emulator has full control over the virtual environment that the game is running in, so there are a few tricks it can pull. As such, additional features such as cheats and save states are common in most emulators. It’s even possible to swap out the original graphical assets for higher resolution versions, which can greatly improve the look of some early 3D games.

But what if you wanted to take things further? That’s where having the source code makes all the difference. Once you’ve gotten the game running perfectly, you can create a fork that starts adding in new features and quality of life improvements. As an example, the decompilation for Animal Crossing on the GameCube will allow developers to expand the in-game calendar beyond the year 2030 — but it’s a change that will be implemented in a “deluxe” fork of the code so as to preserve how the original game functioned.

At this point you’re beyond preservation, and you’ve turned the game into something that doesn’t just live on, but can actually grow with new generations of players.

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It’s a question new makers often ask: “Should I start with a CNC machine or a 3D Printer?”– or, once you have both, every project gets the question “Should I use my CNC or 3D printer?” — and the answer is to both is, of course, “it depends”. In the video embedded below by [NeedItMakeIt] you can see a head-to-head comparison for one specific product he makes, CRATER, a magnetic, click-together stacking tray for tabletop gaming. (He says tabletop gaming, but we think these would be very handy in the shop, too.)

[NeedItMakeIt] takes us through the process for both FDM 3D Printing in PLA, and CNC Machining the same part in walnut. Which part is nicer is absolutely a matter of taste; we can’t imagine many wouldn’t chose the wood, but *de gustibus non disputandum est–*there is no accounting for taste. What there is accounting for is the materials and energy costs, which are both surprising– that walnut is cheaper than PLA for this part is actually shocking, but the amount of power needed for dust collection is something that caught us off guard, too.

Of course the process is the real key, and given that most of the video follows [NeedItMakeIt] crafting the CNC’d version of his invention, the video gives a good rundown to any newbie just how much more work is involved in getting a machined part ready for sale compared to “take it off the printer and glue in the magnets.” (It’s about 40 extra minutes, if you want to skip to the answer.) As you might expect, labour is by far the greatest cost in producing these items if you value your time, which [NeedItMakeIt] does in the spreadsheet he presents at the end.

What he does not do is provide an answer, because in the case of this part, neither CNC or 3D Printing is “better”. It’s a matter of taste– which is the great thing about DIY. We can decide for ourselves which process and which end product we prefer. “There is no accounting for taste”, de gustibus non disputandum est, is true enough that it’s been repeated since Latin was a thing. Which would you rather, in this case? CNC or 3D print? Perhaps you would rather 3D Print a CNC? Or have one machine to do it all? Let us know in the comments for that sweet, sweet engagement.

While you’re engaging, maybe drop us a tip, while we offer our thanks to [Al] for this one.

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We take it for granted that we almost always have cell service, no matter where you go around town. But there are places — the desert, the forest, or the ocean — where you might not have cell service. In addition, there are certain jobs where you must be able to make a call even if the cell towers are down, for example, after a hurricane. Recently, a combination of technological advancements has made it possible for your ordinary cell phone to connect to a satellite for at least some kind of service. But before that, you needed a satellite phone.

On TV and in movies, these are simple. You pull out your cell phone that has a bulkier-than-usual antenna, and you make a call. But the real-life version is quite different. While some satellite phones were connected to something like a ship, I’m going to consider a satellite phone, for the purpose of this post, to be a handheld device that can make calls.

History

Satellites have been relaying phone calls for a very long time. Early satellites carried voice transmissions in the late 1950s. But it would be 1979 before Inmarsat would provide MARISAT for phone calls from sea. It was clear that the cost of operating a truly global satellite phone system would be too high for any single country, but it would be a boon for ships at sea.

Inmarsat, started as a UN organization to create a satellite network for naval operations. It would grow to operate 15 satellites and become a private British-based company in 1998. However, by the late 1990s, there were competing companies like Thuraya, Iridium, and GlobalStar.

An IsatPhone-Pro (CC-BY-SA-3.0 by [Klaus Därr])The first commercial satellite phone call was in 1976. The oil platform “Deep Sea Explorer” had a call with Phillips Petroleum in Oklahoma from the coast of Madagascar. Keep in mind that these early systems were not what we think of as mobile phones. They were more like portable ground stations, often with large antennas.

For example, here was part of a press release for a 1989 satellite terminal:

…small enough to fit into a standard suitcase. The TCS-9200 satellite terminal weighs 70lb and can be used to send voice, facsimile and still photographs… The TCS-9200 starts at $53,000, while Inmarsat charges are $7 to $10 per minute.

Keep in mind, too, that in addition to the briefcase, you needed an antenna. If you were lucky, your antenna folded up and, when deployed, looked a lot like an upside-down umbrella.

However, Iridium launched specifically to bring a handheld satellite phone service to the market. The first call? In late 1998, U.S. Vice President Al Gore dialed Gilbert Grosvenor, the great-grandson of Alexander Graham Bell. The phones looked like very big “brick” phones with a very large antenna that swung out.

Of course, all of this was during the Cold War, so the USSR also had its own satellite systems: Volna and Morya, in addition to military satellites.

Location, Location, Location

The earliest satellites made one orbit of the Earth each day, which means they orbit at a very specific height. Higher orbits would cause the Earth to appear to move under the satellite, while lower orbits would have the satellite racing around the Earth.

That means that, from the ground, it looks like they never move. This gives reasonable coverage as long as you can “see” the satellite in the sky. However, it means you need better transmitters, receivers, and antennas.

Iridium satellites are always on the move, but blanket the earth.

This is how Inmarsat and Thuraya worked. Unless there is some special arrangement, a geosynchronous satellite only covers about 40% of the Earth.

Getting a satellite into a high orbit is challenging, and there are only so many “slots” at the exact orbit required to be geosynchronous available.  That’s why other companies like Iridium and Globalstar wanted an alternative.

That alternative is to have satellites in lower orbits. It is easier to talk to them, and you can blanket the Earth. However, for full coverage of the globe, you need at least 40 or 50 satellites.

The system is also more complex. Each satellite is only overhead for a few minutes, so you have to switch between orbiting “cell towers” all the time. If there are enough satellites, it can be an advantage because you might get blocked from one satellite by, say, a mountain, and just pick up a different one instead.

Globalstar used 48 satellites, but couldn’t cover the poles. They eventually switched to a constellation of 24 satellites. Iridium, on the other hand, operates 66 satellites and claims to cover the entire globe. The satellites can beam signals to the Earth or each other.

The Problems

There are a variety of issues with most, if not all, satellite phones. First, geosynchronous satellites won’t work if you are too far North or South since the satellite will be so low, you’ll bump into things like trees and mountains. Of course, they don’t work if you are on the wrong side of the world, either, unless there is a network of them.

Getting a signal indoors is tricky. Sometimes, it is tricky outdoors, too. And this isn’t cheap. Prices vary, but soon after the release, phones started at around $1,300, and then you paid $7 a minute to talk. The geosynchronous satellites, in particular, are subject to getting blocked momentarily by just about anything. The same can happen if you have too few satellites in the sky above you.

Modern pricing is a bit harder to figure out because of all the different plans. However, expect to pay between $50 and $150 a month, plus per-minute charges ranging from $0.25 to $1.50 per minute. In general, networks with less coverage are cheaper than those that work everywhere. Text messages are extra. So, of course, is data.

If you want to see what it really looked like to use a 1990-era Iridium phone, check out [saveitforparts] video below.

If you prefer to see an older non-phone system, check him out with an even older Inmarsat station in this video:

So it is no wonder these never caught on with the mass market. We expect that if providers can link normal cell phones to a satellite network, these older systems will fall by the wayside, at least for voice communications. Or, maybe hacker use will get cheaper. We can hope, right?

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Time series of O2 (blue) and VGADM (red). (Credit: Weijia Kuang, Science Advances, 2025)

In an Earth-sized take on the age-old ‘correlation or causality’ question, researchers have come across a fascinating match between Earth’s magnetic field and its oxygen levels since the Cambrian explosion, about 500 million years ago. The full results by [Weijia Kuang] et al. were published in Science Advances, where the authors speculate that this high correlation between the geomagnetic dipole and oxygen levels as recorded in the Earth’s geological mineral record may be indicative of the Earth’s geological processes affecting the evolution of lifeforms in its biosphere.

As with any such correlation, one has to entertain the notion that said correlation might be spurious or indirectly related before assuming a strong causal link. Here it is for example known already that the solar winds affect the Earth’s atmosphere and with it the geomagnetic field, as more intense solar winds increase the loss of oxygen into space, but this does not affect the strength of the geomagnetic field, just its shape. The question is thus whether there is a mechanism that would affect this field strength and consequently cause the loss of oxygen to the solar winds to spike.

Here the authors suggest that the Earth’s core dynamics – critical to the geomagnetic field – may play a major role, with conceivably the core-mantle interactions over the course of millions of years affecting it. As supercontinents like Pangea formed, broke up and partially reformed again, the impact of this material solidifying and melting could have been the underlying cause of these fluctuations in oxygen and magnetic field strength levels.

Although hard to say at this point in time, it may very well be that this correlation is causal, albeit as symptoms of activity of the Earth’s core and liquid mantle.

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QR codes are something that we all take for granted in this day and age. There are even a million apps to create your own QR codes, but what if you want to make a barcode? How about making a specific kind of barcode that follows UPC-E, CODE 39, or even the infamous… CODABAR? Well, it might be more difficult to find a single app that can handle all those different standards. Using “yet-another-web-app”, Barcode Tool – Generator & Scanner, you can rid these worries, created by [Ricardo de Azambuja].

When going to [Ricardo]’s simple application, you will find a straightforward interface that allows you to make far more different strips and square patterns than you’ve ever imagined. Of course, starting with the common QR code, you can create custom overlaid codes like many other QR generators. More uniquely, there are options for any barcode under the sun to help organize your hacker workspace. If you don’t want to download an app to scan the codes, you can even use the included scanner function.

If you want to use the web app, you can find it here! In-depth solutions to rather simple problems are something we strive to provide here at Hackaday, and this project is no exception. However, if you want something more physical, check out this specialized outdoor city cooking station.

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Learning new instruments is never a simple task on your own; nothing can beat the instant feedback of a teacher. In our new age of AI, why not have an AI companion complain when you’re off note? This is exactly what [Ada López] put together with their AI-Powered Piano Trainer.

The basics of the piano rely on rather simple boolean actions, either you press a key or not. Obviously, this sets up the piano for many fun projects, such as creative doorbells or helpful AI models. [Ada López] started their AI model with a custom dataset with images of playing specific notes on the piano. These images then get fed into Roboflow and trained using the YOLOv8 model.

Using the piano training has the model run on a laptop and only has a Raspberry Pi for video, and gives instant feedback to the pianist due to the demands of the model. Placing the Pi and an LCD screen for feedback into a simple enclosure allows the easy viewing of how good an AI model thinks you play piano. [Ada López] demos their device by playing Twinkle Twinkle Little Star but there is no reason why other songs couldn’t be added!

While there are simpler piano trainers out there relying on audio cues, this project presents a great opportunity for a fun project for anyone else wanting to take up the baton. If you want to get a little more from having to do less in the physical space, then this invisible piano is perfect for you!

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When seeing a story from MIT’s Lincoln Labs that promises 3D printing glass, our first reaction was that it might use some rare or novel chemicals, and certainly a super-high-tech printer. Perhaps it was some form of high-temperature laser sintering, unlikely to be within the reach of mere mortals. How wrong we were, because these boffins have developed a way to 3D print a glass-like material using easy-to-source materials and commonly available equipment.

The print medium is sodium silicate solution, commonly known as waterglass, mixed with silica and other inorganic nanoparticles. It’s referred to as an ink, and it appears to be printed using a technique very similar to the FDM printers we all know. The real magic comes in the curing process, though, because instead of being fired in a special furnace, these models are heated to 200 Celsius in an oil bath. They can then be solvent cleaned and are ready for use. The result may not be the fine crystal glass you may be expecting, but we can certainly see plenty of uses for it should it be turned into a commercial product. Certainly more convenient than sintering with a laser cutter.

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Hold onto your hats, everyone — there’s stunning news afoot. It’s hard to believe, but it looks like over-reliance on chatbots to do your homework can turn your brain into pudding. At least that seems to be the conclusion of a preprint paper out of the MIT Media Lab, which looked at 54 adults between the ages of 18 and 39, who were tasked with writing a series of essays. They divided participants into three groups — one that used ChatGPT to help write the essays, one that was limited to using only Google search, and one that had to do everything the old-fashioned way. They recorded the brain activity of writers using EEG, in order to get an idea of brain engagement with the task. The brain-only group had the greatest engagement, which stayed consistently high throughout the series, while the ChatGPT group had the least. More alarmingly, the engagement for the chatbot group went down even further with each essay written. The ChatGPT group produced essays that were very similar between writers and were judged “soulless” by two English teachers. Go figure.

The most interesting finding, though, was when 18 participants from the chatbot and brain-only groups were asked to rewrite one of their earlier essays, with the added twist that the chatbot group had to do it all by themselves, while the brainiacs got to use ChatGPT. The EEGs showed that the first group struggled with the task, presumably because they failed to form any deep memory of their previous work thanks to over-reliance on ChatGPT. The brain-only folks, however, did well at the task and showed signs of activity across all EEG bands. That fits well with our experience with chatbots, which we use to help retrieve specific facts and figures while writing articles, especially ones we know we’ve seen during our initial scan of the literature but can’t find later.

Does anyone remember Elektro? We sure do, although not from personal experience, since the seven-foot-tall automaton built by Westinghouse for the World’s Fair in New York City in 1939 significantly predates our appearance on the planet. But still, the golden-skinned robot that made its living by walking around, smoking, and cracking wise at the audience thanks to a 78-rpm record player in its capacious chest, really made an impression, enough that it toured the country for the better part of 30 years and made the unforgettable Sex Kittens Go to College in 1960 before fading into obscurity. At some point, the one-of-a-kind robot was rescued from a scrap heap and restored to its former glory, and now resides in the North Central Ohio Industrial Museum in Mansfield, very close to the Westinghouse facility that built it. If you need an excuse to visit North Central Ohio, you could do worse than a visit to see Elektro.

It was with some alarm that we learned this week from Al Williams that mtrek.com 1701 appeared to be down. For those not in the know, mtrek is a Telnet space combat game inspired by the Star Trek franchise, which explains why Al was in such a tizzy about not being able to connect; huge Trek nerd, our Al. Anyway, it appears Al’s worst fears were unfounded, as we were able to connect to mtrek just fine. But in the process of doing so, we stumbled across this collection of Telnet games and demos that’s worth checking out. The mtrek, of course, as well as Telnet versions of chess and backgammon, and an interactive world map that always blows our mind. The site also lists the Telnet GOAT, the Star Wars Asciimation; sadly, that one does seem to be down, at least for us. Sure, you can see it in a web browser, but it’s not the same as watching it in a terminal over Telnet, is it?

And finally, if you’ve got 90 minutes or so to spare, you could do worse than to spend it with our friend Hash as he reverse engineers an automotive ECU. We have to admit that we haven’t indulged yet — it’s on our playlist for this weekend, because we know how to party. But from what Hash tells us, this is the tortured tale of a job that took far, far longer to complete than expected. We have to admit that while we’ll gladly undertake almost any mechanical repair on most vehicles, automotive ECUs and other electronic modules are almost a bridge too far for us, at least in terms of cracking them open to make even simple repairs. Getting access to them for firmware extraction and parameter fiddling sounds like a lot of fun, and we’re looking forward to hearing what Hash has to say about the subject.

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Look out of a window, ask yourself the question, “Has a nuke gone off?”. Maybe, maybe not, and all of us here at Hackaday need to know the answer to these important questions! Introducing the hasanukegoneoff.com Indicator from [bigcrimping] to answer our cries.

An ESP32 running a MicroPython script handles the critical checks from hasanukegoneoff.com for any notification of nuclear mayhem. This will either power the INS-1 neon bulb, indicating “no” or “yes” in the unfortunate case of a blast. Of course, there is also the button required for testing the notification lights; no chance of failure can be left. All of this is fitted onto a custom dual-sided PCB and placed inside a custom 3D-printed enclosure.

Hasanukegoneoff.com’s detection system, covered before here, relies on an HSN-1000L Nuclear Event Detector to check for neutrons coming from the blast zone. [bigcrimping] also provides the project plans for your own blast detector to answer the critical question of “has a nuke gone off” from anywhere other than the website’s Chippenham, England location.

This entire project is open sourced, so keep sure to check out [bigcrimping]’s GitHub for both portions of this project on the detector and receiver. While this project provides some needed dark humor, nukes are still scary and especially so when disarming them with nothing but a hacksaw and testing equipment.

Thanks to [Daniel Gooch] for the tip.

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Maybe your goal is to preserve the heyday of rail travel with a precise scale replica of a particular railroad station. Maybe you’re making a hyper-local edition of Monopoly in which the houses and hotels are the actual houses and hotels in your hometown.

Whatever the reason, if you have need for shrinkifying a building or other reasonably large object, there is (at least) one sure-fire way to do it, and [ nastideplasy ] is your guide with this tutorial on drone photogrammetry.

The process is essentially the same as any other photogrammetry you may have seen before—take lots of overlapping photos of an object from many different angles around it, stitch those photos together, make a 3D mesh by triangulating corresponding points from multiple photos—but this time the photos are captured by drone, allowing for much larger subjects, so long as you can safely and legally fly a drone around it.

The challenge, of course, is capturing a sufficient number of overlapping photos such that your reconstruction software can process them into a clean 3D mesh. Where purpose-built 3D scanners, automatic turntables, or a steady hand and lots of patience worked well at a smaller scale, skill with a pair of control sticks is the key to getting a good scan of a house.

[ nastideplasy ] also points out the importance of lighting. Direct sunlight and deep shadows can cause issues when processing the images, and doing this at night is almost certainly out of the question. Overcast days are your best bet for a clean scan.

The tutorial calls for software from Autodesk to stitch photos and clean up 3D meshes. We’ve also seen some excellent results with open source options like Meshroom as well.

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As far as giving mechanical instruments electronic control goes, drums are probably the best candidate for conversion; learning to play them is challenging and loud for a human, but they’re a straightforward matter for a microcontroller. [Jeremy Cook]’s latest project takes this approach by using an Arduino Opta to play a tongue drum. [Jeremy]’s design far the drum controller was inspired by the ring-shaped arrangement of the Cray 2 supercomputer. A laser-cut MDF frame forms a C-shape around the tongue drum, and holds eight camera mount friction arms. Each friction arm holds a solenoid above a different point on the drum head, making it easy to position them. A few supports were 3D-printed, and some sections of PVC tubing form pivots to close the ring frame. [Jeremy] found that the the bare metal tips of the solenoids made a harsh sound against the drum, so he covered the tips of six solenoids with plastic caps, while the other two uncoated tips provide an auditory contrast.The Arduino Opta is an open-source programmable logic controller normally intended for industrial automation. Here, its silent solid-state relays drive the solenoids, as [Jeremy]’s done before in an earlier experiment. The Opta is programmed to accept MIDI input, which [Jeremy] provided from two of the MIDI controllers which we’ve seen him build previously. He was able to get it working in time for the 2024 Orlando Maker Faire, which was the major time constraint.Of course, for a project like this you need a MIDI controller, and we’ve previously seen [Jeremy] convert a kalimba into such a controller. We’ve seen this kind of drum machine at least once before, but it’s more common to see a purely electronic implementation.

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Over on his YouTube channel our hacker [CircuitValley] repairs an old TDS8000 scope.

The TDS8000 was manufactured by Tektronix circa 2001 and was also marketed as the CSA8000 Communications Signal Analyzer as well as the TDS8000 Digital Sampling Oscilloscope. Tektronix is no longer manufacturing and selling these scopes but the documentation is still available from their website, including the User Manual (268 page PDF), the Service Manual (198 page PDF), and some basic specs (in HTML).

You can do a lot of things with a TDS8000 scope but particularly its use case was Time-Domain Reflectometry (TDR). A TDR scope is the time-domain equivalent of a Vector Network Analyzer (VNA) which operates in the frequency-domain.

The TDS8000 needs sampling heads attached and it has two large slots on the front for optical sampling heads and four smaller slots for electrical sampling heads. In this video we don’t see any sampling heads actually used, the only thing we see in this video is troubleshooting and repair of the TDS8000 itself. The effective bandwidth of the scope is limited by the capabilities of the sampling heads but according to its datasheet can extend up to 50 GHz, which is seriously large, especially by the standards of 2001!

[CircuitValley] cleans, replaces, upgrades, and fixes a bunch of things during the service of this TDS8000 and documents the process in this YouTube video. In the end he seems to have fixed the problem the scope had in the beginning, where it would hang while loading its main application. We’d love to hear from [CircuitValley] again some time to see a complete system operating with sampling heads attached.

If you’re interested in old scope repair too, then how far back in time did you want to go? Maybe you could start at Recovering An Agilent 2000a/3000a Oscilloscope With Corrupt Firmware NAND Flash and then work your way back to Repairing An Old Heathkit ‘Scope.

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If you’ve put in all the necessary practice to learn bike tricks, you’d probably like an appropriately dramatic soundtrack to accompany your stunts. A team of students working on a capstone project at the University of Washington took this natural desire a step further with the Music Bike, a system that generates adaptive music in response to the bike’s motion.

The Music Bike has a set of sensors controlled by an ESP32-S3 mounted beneath the bike seat. The ESP32 transmits the data it collects over BLE to an Android app, which in turn uses the FMOD Studio adaptive sound engine to generate the music played. An MPU9250 IMU collects most position and motion data, supplemented by a hall effect sensor which tracks wheel speed and direction of rotation.

When the Android app receives sensor data, it performs some processing to detect the bike’s actions, then uses these to control FMOD’s output. The students tried using machine learning to detect bike tricks, but had trouble with latency and accuracy, so they switched to a threshold classifier. They were eventually able to detect jumps, 180-degree spins, forward and reverse motion, and wheelies. FMOD uses this information to modify music pitch, alter instrument layering, and change the track. The students gave an impressive in-class demonstration of the system in the video below (the demonstration begins at 4:30).

Surprisingly enough, this isn’t the first music-producing bike we’ve featured here. We’ve also seen a music-reactive bike lighting system.

Thanks to [Blake Hannaford] for the tip!

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Coming in hot from Cornell University, students [Amanda Huang], [Caroline Hohner], and [Rhea Goswami] bring a project that is guaranteed to tickle the funny bone of anyone in the under-40 set, and sadists of all ages: The Tamagochi Torture Chamber.

He’s dead, Jim.

In case you somehow missed it, Bandai’s Tamagochi is a genre-defining digital pet that was the fad toy at the turn of the millennium, and has had periodic revivals since. Like the original digital pet, there are three pushbuttons to allow you to feed, play with, and clean your digital pet. These affect the basic stats of happiness, health, food and weight in ways that will be familiar to anyone who played with the original Tamagochi. Just as with the original, mistreatment or neglect causes the Tamagochi to “die” and display a tombstone on the TFT display.

Where the “Torture Chamber” part comes in is the presence of an accelerometer and soft physics simulation– the soft physics gets an entire core of the Pi Pico at the heart of this build dedicated to it, while the other core handles all inputs, display and game logic. What this enables is the ability to bounce the digital pet off the walls of its digital home with an adorable squish (and drop in health stat) by tilting the unit. You can check that out in the demo video blow.

Is it overkill for a kids toy to have a full soft body simulation, rather than just a squish-bounce animation? Probably, but for an ECE project, it lets the students show off their chops… and possibly work out some frustrations.

We won’t judge. We will point you to other Tamagotchi-inspired projects, though: like this adorable fitness buddy, or this depressingly realistic human version.

If you’ve got an innovative way to torture video game characters, or a project less likely to get you on Skynet’s hitlist, don’t forget to send in a tip!

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Currently the typical way that crude oil is processed involves a fractional distillation column, in which heated crude oil is separated into the various hydrocarbon compounds using distinct boiling points. This requires the addition of significant thermal energy and is thus fairly energy intensive. A possible alternative has been proposed by [Tae Hoon Lee] et al. with a research article in Science. They adapted membranes used with reverse-osmosis filtration to instead filter crude oil into its constituents, which could enable skipping the heating step and thus save a lot of energy.

The main change that had to be made was to replace the typical polyamide films with polyimine ones, as the former have the tendency to swell up – and thus becomes less effective – when exposed to organic solvents, which includes hydrocarbons. During testing, including with a mixture of naphtha, kerosene and diesel, the polyimine membrane was able to separate these by their molecular size.

It should be noted of course that this is still just small scale lab-testing and the real proof will be in whether it can scale up to the flow rates and endurance required from a replacement for a distillation column. Since this research is funded in part by the fossil fuel industry, one can at least expect that some trial installations will be set up before long, with hopefully positive results.

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Starting June 20th, any cordless phone, smartphone, or feature phone, as well as tablets (7 – 17.4″ screens) have to meet Ecodesign requirements. In addition there is now mandatory registration with the European Product Registry for Energy Labelling (EPREL). The only exception are phones and tablets with a flexible (rollable) main display, and tablets that do not use a mobile OS, i.e. not Android, iPadOS, etc. These requirements include resistance to drops, scratches and water, as well as batteries that last at least 800 cycles.

What is perhaps most exciting are the requirements that operating system updates must be made available for at least five years from when the product is last on the market, along with spare parts being made available within 5-10 working days for seven years after the product stops being sold. The only big niggle here is that this access only applies to ‘professional repairers’, but at least this should provide independent repair shops with full access to parts and any software tools required.

On the ENERGY label that is generated with the registration, customers can see the rating for each category, including energy efficiency, battery endurance, repairability and IP (water/dust ingress) rating, making comparing devices much easier than before. All of this comes before smartphones and many other devices sold in the EU will have to feature easily removable batteries by 2027, something which may make manufacturers unhappy, but should be a boon to us consumers and tinkerers.

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Here’s a great hack sent in to us from [Simon]. He uses an e-paper photo frame as a weather map!

By now you are probably aware of e-paper technology, which is very low power tech for displaying images. E-paper only uses energy when it changes its display, it doesn’t draw power to maintain a picture it has already rendered. The particular e-paper used in this example is fairly large (as e-paper goes) and supports color (not just black and white) which is why it’s expensive. For about US$100 you can get a 5.7″ 7-color EPD display with 600 x 448 pixels.

Beyond the Inky Frame 5.7″ hardware this particular hack is mostly a software job. The first program, written in python, collects weather data from the UK Met Office. Once that image data is available a BASH script is run to process the image files with imagemagick. Finally a Micro Python script runs on the Pico to download the correct file based on the setting of the real-time clock, and update the e-paper display with the weather map.

Thanks to [Simon] for sending this one in via the tipsline. If you have your own tips, please do let us know! If you’re interested in e-paper tech we have certainly covered that here in the past, check out E-Paper Anniversary Counter Is A Charming Gift With Minimal Power Draw and A Neat E-Paper Digit Clock (or Four).

The video below the break is a notice from the UK Met Office regarding their data services.

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Before YouTube, you had to watch your educational videos on film. In the 1970s, if you studied radio, you might have seen the video from Universal Education and Visual Arts, titled Understanding Electronics Basic Radio Circuitry. The video’s been restored, and it appears on the [CHAP] YouTube channel.

The video starts with a good history lesson that even covers Fessenden, which you rarely hear about. The video is full of old components that you may or may not remember, depending on your age. There’s a classic crystal radio at the start and it quickly moves to active receivers. There’s probably nothing in here you don’t already know. On the other hand, radios work about the same today as they did in the 1970s, unless you count software-defined varieties.

We expect this was produced for the “trade school” market or, maybe, a super advanced high school shop class. There were more in the series, apparently, including ones on vacuum tubes, the transistor, and the principles of television.

We were sad that the credits don’t mention the narrator. He sounded familiar. Maybe Robert Vaughn? Maybe not. A little research indicates the company was a division of Universal Studios, although the Library of Congress says it was actually produced by  Moreland-Latchford Productions in Toronto.

Maybe these videos were the next step in becoming a child radio engineer. If you like old radio videos, this one is even older.

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I was watching Ben Krasnow making iron nitride permanent magnets and was struck by the fact that about half of the video was about making a magnetometer – a device for measuring and characterizing the magnet that he’d just made. This is really the difference between doing science and just messing around: if you want to test or improve on a procedure, you have to be able to measure how well it works.

When he puts his home-made magnet into the device, Ben finds out that he’s made a basically mediocre magnet, compared with samples out of his amply stocked magnet drawer. But that’s a great first data point, and more importantly, the magnetometer build gives him a way of gauging future improvements.

Of course there’s a time and a place for “good enough is good enough”, and you can easily spend more time building the measurement apparatus for a particular project than simply running the experiment, but that’s not science. Have you ever gone down the measurement rabbit hole, spending more time validating or characterizing the effect than you do on producing it in the first place?

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We like scale models here, but how small can you shrink the very large? If you’re [Frans], it’s pretty small indeed: his Micro Tellurium fits the orbit of the Earth on top of an ordinary pencil. While you’ll often see models of Earth, Moon and Sun’s orbital relationship called “Orrery”, that’s word should technically be reserved for models of the solar system, inclusive of at least the classical planets, like [Frans]’s Gentleman’s Orrery that recently graced these pages. When it’s just the Earth, Moon and Sun, it’s a Tellurium.

The whole thing is made out of brass, save for the ball-bearings for the Earth and Moon. Construction was done by a combination of manual milling and CNC machining, as you can see in the video below. It is a very elegant device, and almost functional: the Earth-Moon system rotates, simulating the orbit of the moon when you turn the ring to make the Earth orbit the sun. This is accomplished by carefully-constructed rods and a rubber O-ring.

Unfortunately, it seems [Franz] had to switch to a thicker axle than originally planned, so the tiny moon does not orbit Earth at the correct speed compared to the solar orbit: it’s about half what it ought to be. That’s unfortunate, but perhaps that’s the cost one pays when chasing smallness. It might be possible to fix in a future iteration, but right now [Franz] is happy with how the project turned out, and we can’t blame him; it’s a beautiful piece of machining.

It should be noted that there is likely no tellurium in this tellurium — the metal and the model share the same root, but are otherwise unrelated. We have featured hacks with that element, though.

Thanks to [Franz] for submitting this hack. Don’t forget: the tips line is always open, and we’re more than happy to hear you toot your own horn, or sing the praises of someone else’s work.

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To paraphrase an old joke: How do you know if someone is a Rust developer? Don’t worry, they’ll tell you. There is a move to put Rust everywhere, even in the Linux kernel. Not going fast enough for you? Then check out Asterinas — an effort to create a Linux-compatible kernel totally in Rust.

The goal is to improve memory safety and, to that end, the project describes what they call a “framekernel.” Historically kernels have been either monolithic, all in one piece, or employ a microkernel architecture where only bits and pieces load.

A framekernel is similar to a microkernel, but some services are not allowed to use “unsafe” Rust. This minimizes the amount of code that — in theory — could crash memory safety. If you want to know more, there is impressive documentation. You can find the code on GitHub.

Will it work? It is certainly possible. Is it worth it? Time will tell. Our experience is that no matter how many safeguards you put on code, there’s no cure-all that prevents bad programming. Of course, to take the contrary argument, seat belts don’t stop all traffic fatalities, but you could just choose not to have accidents. So we do have seat belts. If Rust can prevent some mistakes or malicious intent, maybe it’s worth it even if it isn’t perfect.

Want to understand Rust? Got ten minutes?

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Have you ever finished up a bit of code and thought that typing “git push” in a terminal is just not a satisfying finish? So did [penumbriel], so he built a big red button he could smash instead.

This is a very simple hack: an Arduino sits inside a 3D-printed case that holds a big, red button. The case itself is very sturdily made to withstand a good satisfying smack: it has thick walls, brass insets, and rubber feet to protect the de The code for the Arduino is very, very simple: it spoofs a USB HID using the standard keyboard library, and automatically types out “git push” whenever the button is pressed. Or smashed, because you know you’re going to want to slam that thing. So far, so good– very innovative for 2006, right?

The detail that made this project stand out in 2025 was the technique [penumbriel] used for lettering– we’re always looking

With a simple soap-and-water mask, the cured silicone peels right off, leaving a clean label.

for new ways to make a good front panel. In this case, the letters were printed as a valley, and filled with silicone adhesive. To protect the top surface of the print, soapy water was used as a mask. The silicone would not adhear to the wet plastic, so all [penumbriel] had to do was peel it off after it had cured, leaving solid white inside. It’s a neat trick, and a great way to use up an old tube of silicone before it goes hard. You could also use it for injection molding, but this is a great use for the dregs.

This might go well next to the programmer’s macro pad we featured a while back, but it really needs to stay as a big red button for maximum satisfaction.

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The last time we checked in with the ELIZA archeology project, they had unearthed the earliest known copy of the code for the infamous computer psychiatrist written in MAD-SLIP. After a lot of work, that version is now running again, and there were a number of interesting surprises.

While chatbots are all the modern rage, [Joseph Weizenbaum] created what could be the first one, ELIZA, in the mid-1960s. Of course, it wasn’t as capable as what we have today, but it is a good example of how simple it is to ape human behavior.

The original host was an IBM 7094, and MAD-SLIP fell out of favor. Most versions known previously were in Lisp or even Basic. But once the original code was found, it wasn’t enough to simply understand it. They wanted to run it.

Fortunately, there is an emulator for the IBM 7094. MAD-SLIP is around, too, but for whatever reason, didn’t support all the functions that [Weizenbaum] had used. The 2,600 lines of code are mostly undocumented, and the only copy was on fanfold printer paper, so the first step was getting the text in digital form.

Once it was manually transcribed, they found some functions were missing in their MAD-SLIP version. Rewriting the functions and correcting a typo made everything work.

The original version had a learning mode that did not carry over to the later clones. There’s an example of how to teach new rules in the paper. You can also see a video (below) of the original code duplicating (nearly) the original published conversations from the 1966 paper.

We have been following the team for some time and they’ve made their work available if you want to try it. We have thought a lot about Eliza since the chatbots have started taking over.

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PVA filament with a core. (Credit: Lost In Tech)

PVA filament is an interesting filament type, for the reason that while it can be printed with any FDM printer, it supposedly readily dissolves in water, which is also the reason why PVA glue sticks are so popular when doing crafts and arts with young children. This property would make PVA filament ideal for printing supports if your printer can handle two different materials at the same time. So surely you can just pick any old PVA filament spool and get to printing, right? As [Lost in Tech] found out, this is not quite the case.

As an aside, watching PVA supports dissolve in water set to classical music (Bach’s Air from Orchestral Suite No. 3) is quite a pleasant vibe. After thus watching the various PVA prints dissolve for a while, we are left to analyze the results. The first interesting finding was that not every PVA filament dissolved the same way, or even fully.

The first gotcha is that PVA can stand for polyvinyl acetate (the glue stick) or polyvinyl alcohol (a thickener and stabilizer) , with the ‘PVA’ filament datasheets for each respective filament showing various combinations of both types of PVA. This results in wildly different properties per filament, both in terms of Shore hardness, their printability, as well as their ability to dissolve in water. Some of the filament types (Yousu, Reprapper) also have an outer layer and inner core for some reason.

Ultimately the message appears to be that ‘PVA’ filament requires a fair bit of research to have any chance of having a relatively trouble-free printing experience.

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