Old-school technology can spark surprising innovations. By combining the vintage zoetrope concept with digital displays, [Mike Ando] created the Andotrope, a surprisingly simple omnidirectional display.

Unlike other 3D displays, the Andotrope lets you view a normal 2D video or images that appear identical irrespective of your viewing angle. The prototype demonstrated in the video below consists of a single smart phone and a black cylinder spinning at 1,800 RPM. A narrow slit in front of each display creates a “scanning” view that our brain interprets as a complete image, thanks to persistence of vision. [Mike] has also created larger version with a higher frame rate, by mounting two tablets back-to-back.

Surprisingly, the Andotrope appears to be an original implementation, and neither [Mike] nor we can find any similar devices with a digital display. We did cover one that used a paper printout in a a similar fashion. [Mike] is currently patenting his design, seeing the potential for smaller displays that need multi-angle visibility. The high rotational speed creates significant centrifugal force, which might limit the size of installations. Critically, display selection matters — any screen flicker becomes glaringly obvious at speed.

This device might be the first of its kind, but we’ve seen plenty of zoetropes over the years, including ones with digital displays or ingenious time-stretching tricks.

Whether you’re a kid or a kid at heart, learning about science and engineering can be a lot more fun if it’s practical. You could sit around learning about motors and control theory, or you could build a robot arm and play with it. If the latter sounds like your bag of hammers, you might like Pedro 2.0.

Pedro 2.0 is a simple 3D-printable robot arm intended for STEAM education. If you’re new to that acronym, it basically refers to the combination of artistic skills with education around science, technology, engineering and mathematics.

The build relies on components that are readily available pretty much around the world—SG90 servo motors, ball bearings, and an Arduino running the show. There’s also an NRF24L01 module for wireless remote control. All the rest of the major mechanical parts can be whipped up on a 3D printer, and you don’t need a particularly special one, either. Any old FDM machine should do the job just fine if it’s calibrated properly.

If you fancy dipping your toes in the world of robot arms, this is a really easy starting point that will teach you a lot along the way. From there, you can delve into more advanced designs, or even consider constructing your own tentacles. The world really is your octopus oyster.

When electronics release the Magic Smoke, more often than not it’s a fairly sedate event. Something overheats, the packaging gets hot enough to emit that characteristic and unmistakable odor, and wisps of smoke begin to waft up from the defunct component. Then again, sometimes the Magic Smoke is more like the Magic Plasma, as was the case in this absolutely smoked Omron programmable logic controller.

Normally, one tasked with repairing such a thing would just write the unit off and order a replacement. But [Defpom] needed to get the pump controlled by this PLC back online immediately, leading to the somewhat unorthodox repair in the video below. Whatever happened to this poor device happened rapidly and energetically, taking out two of the four relay-controlled outputs. [Defpom]’s initial inspection revealed that the screw terminals for one of the relays no longer existed, one relay enclosure was melted open, its neighbor was partially melted, and a large chunk of the PCB was missing. Cleaning up the damaged relays revealed what the “FR” in “FR4” stands for, as the fiberglass weave of the board was visible after the epoxy partly burned away before self-extinguishing.

With the damaged components removed and the dangerously conductive carbonized sections cut away, [Defpom] looked for ways to make a temporary repair. The PLC’s program was locked, making it impossible to reprogram it to use the unaffected outputs. Instead, he redirected the driver transistor for the missing relay two to the previously unused and still intact relay one, while adding an outboard DIN-mount relay to replace relay three. In theory, that should allow the system to work with its existing program and get the system back online.

Did it work? Sadly, we don’t know, as the video stops before we see the results. But we can’t see a reason for it not to work, at least temporarily while a new PLC is ordered. Of course, the other solution here could have been to replace the PLC with an Arduino, but this seems like the path of least resistance. Which, come to think of it, is probably what caused the damage in the first place.

Magnetic skyrmions are an interesting example of solitons that occurs in ferromagnetic materials with conceivable solutions in electronics, assuming they can be created and moved at will. The creation and moving of such skyrmions has now been demonstrated by [Yubin Ji] et al. with a research article in Advanced Materials. This first ever achievement by these researchers of the Korea Research Institute of Standards and Science (KRISS) was more power efficient than previously demonstrated manipulation of magnetic skyrmions in thicker (3D) materials.

Magnetic skyrmions are sometimes described as ‘magnetic vortices’, forming statically stable solitons. In a broader sense skyrmions are a topologically stable field configuration in particle physics where they form a crucial part of the emerging field of spintronics. For magnetic skyrmions their stability comes from the topological stability, as changing the atomic spin of the atoms inside the skyrmion would require overcoming a significant energy barrier.

In the case of the KRISS researchers, electrical pulses together with a  magnetic field were used to create magnetic skyrmions in the ferromagnetic  (Fe₃GaTe₂, or FGaT) film, after which a brief (50 µs) electric current pulse was applied. This demonstrated that the magnetic skyrmions can be moved this way, with the solitons moving parallel to the electron flow injection, making them quite steerable.

While practical applications of magnetic skyrmions are likely to be many years off, it is this kind of fundamental research that will enable future magnetic storage and spintronics-related devices.

Featured image: Direct imaging of the magnetic skyrmions. The scale bars represent 300 nm. (Credit:Yubin Ji et al., Adv. Mat. 2024)

If you’re into CNC machining, mechanical tinkering, or just love a good engineering rabbit hole, you’re in for a treat. Substack’s [lcamtuf] has written a quick yet insightful 15-minute introduction to involute gears that’s as informative as it is accessible. You can find the full article here. Compared to Hackaday’s more in-depth exploration in their Mechanisms series over the years, this piece is a beginner-friendly gateway into the fascinating world of gear design.

Involute gears aren’t just pretty spirals. Their unique geometry minimizes friction and vibration, keeps rotational speeds steady, and ensures smooth torque transfer—no snags, no skips. As [lcamtuf] points out, the secret sauce lies in their design, which can’t be eyeballed. By simulating the meshing process between a gear and a rack (think infinite gear), you can create the smooth, rolling movement we take for granted in everything from cars to coffee grinders.

From pressure angles to undercutting woes, [lcamtuf] explores why small design tweaks matter. The pièce de résistance? Profile-shifted gears—a genius hack for stronger teeth in low-tooth-count designs.

Whether you’re into the theory behind gear ratios, or in need of a nifty tool to cut them at home, Hackaday has got you covered. Inspired?

A mouse is just two buttons, and a two-dimensional motion tracking system, right? Oh, and a scroll wheel. And a third button. And…now you’re realizing that mice can be pretty complicated. [DIY Yarik] proves that in spades with his impressive—and complex—mouse build. The only thing is, you might argue it isn’t really a mouse.

The inspiration for the mouse was simple. [Yarik] wanted something that was comfortable to use. He also wanted a mouse that wouldn’t break so often—apparently, he’s had a lot of reliability issues with mice in recent years. Thus, he went with a custom 3D-printed design with a wrist rest at the base. This allows his hand to naturally rest in a position where he can access multiple buttons and a central thumbstick for pointing. In fact, there’s a secondary scroll control and a rotary dial as well. It’s a pretty juicy control surface. Code is up on GitHub.

The use of a thumbstick is controversial—some might exclaim “this is not a mouse!” To them, I say, “Fine, call it a pointing device.” It’s still cool, and it look like a comfortable way to interface with a computer.

We’ve seen some other neat custom mice over the years, too, like this hilarious force-feedback mouse. Video after the break.

With few exceptions, electronic event badges are often all but forgotten as soon as the attendee gets back home. They’re a fun novelty for the two or three days they’re expected to be worn, but after that, they end up getting tossed in a drawer (or worse.) As you might imagine, this can be a somewhat depressing thought thought for the folks who design and build these badges.

But thanks to a new firmware released by the FREE-WILi project, at least one badge is going to get a shot at having a second life. When loaded onto the RP2350-powered DEF CON 32 badge, the device is turned into a handy hardware hacking multi-tool. By navigating through a graphical interface, users will be able to control the badge’s GPIO pins, communicate over I2C, receive and transmit via infrared, and more. We’re particularly interested in the project’s claims that the combination of their firmware and the DC32 badge create an ideal platform for testing and debugging Simple Add-Ons (SAOs).

Don’t know what the FREE-WILi project is? Neither did we until today, which is actually kind of surprising now that we’re getting a good look at it. Basically, it’s a handheld gadget with a dozen programmable GPIO pins and a pair of CC1101 sub-GHz radios that’s designed to talk to…whatever you could possibly want to interface with.

It’s a bit like an even more capable Bus Pirate 5, which considering how many tricks that particular device can pull off, is saying something. As an added bonus, apparently you can even wear the FREE-WILi on your wrist for mobile hardware hacking action!

Anyway, while the hardware in the FREE-WILi is clearly more capable than what’s under the hood of the DC32 badge, there’s enough commonality between them that the developers were able to port a few of the key features over. It’s a clever idea — there’s something like 30,000 of these badges out there in the hands of nerds all over the world, and by installing this firmware, they’ll get a taste of what the project is capable of and potentially spring for the full kit.

If you give your DC32 badge the FREE-WILi treatment, be sure to let us know in the comments.

SpaceX’s Starship is the most powerful launch system ever built, dwarfing even the mighty Saturn V both in terms of mass and total thrust. The scale of the vehicle is such that concerns have been raised about the impact each launch of the megarocket may have on the local environment. Which is why a team from Brigham Young University measured the sound produced during Starship’s fifth test flight and compared it to other launch vehicles.

Published in JASA Express Letters, the paper explains the team’s methodology for measuring the sound of a Starship launch at distances ranging from 10 to 35 kilometers (6 to 22 miles). Interestingly, measurements were also made of the Super Heavy booster as it returned to the launch pad and was ultimately caught — which included several sonic booms as well as the sound of the engines during the landing maneuver.

The paper goes into considerable detail on how the sound produced Starship’s launch and recovery propagate, but the short version is that it’s just as incredibly loud as you’d imagine. Even at a distance of 10 km, the roar of the 33 Raptor engines at ignition came in at approximately 105 dBA — which the paper compares to a rock concert or chainsaw. Double that distance to 20 km, and the launch is still about as loud as a table saw. On the way back in, the sonic boom from the falling Super Heavy booster was enough to set off car alarms at 10 km from the launch pad, which the paper says comes out to a roughly 50% increase in loudness over the Concorde zooming by.

OK, so it’s loud. But how does it compare with other rockets? Running the numbers, the paper estimates that the noise produced during a Starship launch is at least ten times greater than that of the Falcon 9. Of course, this isn’t hugely surprising given the vastly different scales of the two vehicles. A somewhat closer comparison would be with the Space Launch System (SLS); the data indicates Starship is between four and six times as loud as NASA’s homegrown super heavy-lift rocket.

That last bit is probably the most surprising fact uncovered by this research. While Starship is the larger and more powerful  of the two launch vehicles, the SLS is still putting out around half the total energy at liftoff. So shouldn’t Starship only be twice as loud? To try and explain this dependency, the paper points to an earlier study done by two of the same authors which compared the SLS with the Saturn V. In that paper, it was theorized that the arrangement of rocket nozzles on the bottom of the booster may play a part in the measured result.

Hydrogen! It’s a highly flammable gas that seems way too cool to be easy to come by. And yet, it’s actually trivial to make it out of water if you know how. [Maciej Nowak] has shown us how to do just that with his latest build.

The project in question is a simple hydrogen generator that relies on the electrolysis of water. Long story short, run a current through water and you can split H₂O molecules up and make H₂ and O₂ molecules instead. From water, you get both hydrogen to burn and the oxygen to burn it in! Even better, when you do burn the hydrogen, it combines with the oxygen to make water again! It’s all too perfect.

This particular hydrogen generator uses a series of acrylic tanks. Each is fitted with electrodes assembled from threaded rods to pass current through water. The tops of the tanks have barbed fittings which allow the gas produced to be plumbed off to another storage vessel for later use. The video shows us the construction of the generator, but we also get to see it in action—both in terms of generating gas from the water, and that gas later being used in some fun combustion experiments.

Pedants will point out this isn’t really just a hydrogen generator, because it’s generating oxygen too. Either way, it’s still cool. We’ve featured a few similar builds before as well.

Have you ever wondered how a magnetometer works? We sure have, which was why we were happy to stumble upon this article on simple homebrew fluxgate magnetometers.

As [Maurycy] explains, clues to how a fluxgate magnetometer works can be found right in the name. We all know what happens when a current is applied to a coil of wire wrapped around an iron or ferrite core — it makes an electromagnet. Wrap another coil around the same core, and you’ve got a simple transformer.

Now, power the first coil, called the drive coil, with alternating current and measure the induced current on the second, or sense coil. Unexpected differences between the current in the drive coil and the sense coil are due to any external magnetic field. The difference indicates the strength of the field. Genius!

For [Maurycy]’s homebrew version, binocular ferrite cores were stacked one on top of each other and strung together with a loop of magnet wire passing through the lined-up holes in the stack. That entire assembly formed the drive coil, which was wrapped with copper foil to thwart eddy currents. The sense coil was made by wrapping another length of magnet wire around the drive coil package; [Maurycy] found that this orthogonal of coils worked better than an antiparallel coil setup at reducing interference from the powerful drive coil field.

Driving the magnetometer required adding a MOSFET amp to give a function generator a little more oomph. [Maurycy] mentions that scope probes will attenuate the weak sense coil current, so we assume that the sense coil output goes right into the oscilloscope via coax. Calibrating the instrument was accomplished with a homebrew coil and some simple calculations.

This was a great demo of magnetometry methods and some of the intricacies of measuring weak fields with simple instruments. We’ve covered fluxgate magnetometer basics before and even talked about how they made pre-GPS car navigation possible.

You might say that the worst LEGO to step on is any given piece that happens to get caught underfoot, but have you ever thought about what the worst one would really be? For us, those little caltrops come to mind most immediately, and we’d probably be satisfied with believing that was the answer. But not [Nate Scovill]. He had to quantitatively find out one way or another.

And no, the research did not involve stepping on one of each of the thousands of LEGO pieces in existence. [Nate] started by building a test rig that approximated the force of his own 150 lb. frame stepping on each piece under scrutiny and seeing what it did to a cardboard substrate.

And how did [Nate] narrow down which pieces to try? He took to the proverbial streets and asked redditors and Discordians to help him come up with a list of subjects.

If you love LEGO to the point where you can’t bear to see it destroyed, then this video is not for you. But if you need to know the semi-scientific answer as badly as we did, then go for it. The best part is round two, when [Nate] makes a foot out of ballistics gel to rate the worst from the first test. So, what’s the worst LEGO to step on? The answer may surprise you.

And what’s more dangerous than plain LEGO? A LEGO Snake, we reckon.

A conventional tube amplifier has a circuit whose fundamentals were well in place around a hundred years ago, so there are few surprises to be found in building one today. Nevertheless, building one is still a challenge, as [Mike Freda shows us with a stereo amplifier in the video below the break.

The tubes in question are the 12AU7 double triode and 6L6 tetrode, in this case brand new PSVANE parts from China. The design is a very conventional single-ended class A circuit, with both side of the double triode being used for extra gain driving the tetrode. The output uses a tapped transformer with the tap going to the other grid in the tertode, something we dimly remember as being an “ultra-linear” circuit.

There’s an element of workshop entertainment in the video, but aside from that we think it’s the process of characterising the amp and getting its voltages right which is the take-away here. It’s not something many of us do these days, so despite the apparent simplicity of the circuit it’s worth a look.

These modern tubes come from a variety of different sources, we’ve attempted to track them down in the past.

For a time, pocketwatches were all the rage, but they were eventually supplanted by the wristwatch. [abe] built this cyberpunk Lock’n’Watch to explore an alternate history for the once trendy device.

The build was inspired by the chunky looks of Casio sport watches and other plastic consumer electronics from the 1980s and 90s. The electronics portion of this project relies heavily on a 1.28″ Seeed Studio Round Display and a Raspberry Pi 2040 XIAO microcontroller board. The final product features a faux segmented display for information in almost the same color scheme as your favorite website.

[abe] spent a good deal of the time on this project iterating on the bezel and case to hold the electronics in this delightfully anachronistic enclosure. We appreciated the brief aside on the philosophical differences between Blender, TinkerCAD, and Fusion360. Once everything was assembled, he walks us through some of joys of debugging hardware issues with a screen flicker problem. We think the end result really fulfills the vision of a 1980s pocketwatch and that it might be just the thing to go with your cyberdeck.

We’ve seen accelerometers stuffed into old pocketwatch cases, a more useful smart pocketwatch, or you could learn how to repair and restore vintage watches.

This week, Jonathan Bennett, Randal Schwartz, and Aaron Newcomb chat about Linux, the challenges with using system modules like the Raspberry Pi, challenges with funding development, and more!

Did you know you can watch the live recording of the show Right on our YouTube Channel? Have someone you’d like us to interview? Let us know, or contact the guest and have them contact us! Take a look at the schedule here.

Direct Download in DRM-free MP3.

If you’d rather read along, here’s the transcript for this week’s episode.

If you wonder how Large Language Models (LLMs) work and aren’t afraid of getting a bit technical, don’t miss [Brendan Bycroft]’s LLM Visualization. It is an interactively-animated step-by-step walk-through of a GPT large language model complete with animated and interactive 3D block diagram of everything going on under the hood. Check it out!

The demonstration walks through a simple task and shows every step. The task is this: using the nano-gpt model, take a sequence of six letters and put them into alphabetical order.

A GPT model is a highly complex prediction engine, so the whole process begins with tokenizing the input (breaking up words and assigning numerical values to the chunks) and ends with choosing an appropriate output from a list of probabilities. There are of course many more steps in between, and different ways to adjust the model’s behavior. All of these are made quite clear by [Brendan]’s process breakdown.

We’ve previously covered how LLMs work, explained without math which eschews gritty technical details in favor of focusing on functionality, but it’s also nice to see an approach like this one, which embraces the technical elements of exactly what is going on.

We’ve also seen a much higher-level peek at how a modern AI model like Anthropic’s Claude works when it processes requests, extracting human-understandable concepts that illustrate what’s going on under the hood.

SDRs have been a game changer for radio hobbyists, but for ham radio applications, they often need a little help. That’s especially true of SDR dongles, which don’t have a lot of selectivity in the HF bands. But they’re so darn cheap and fun to play with, what’s a ham to do?

[VK3YE] has an answer, in the form of this homebrew software-defined radio (SDR) helper. It’s got a few features that make using a dongle like the RTL-SDR on the HF bands a little easier and a bit more pleasant. Construction is dead simple and based on what was in the junk bin and includes a potentiometer for attenuating stronger signals, a high-pass filter to tamp down stronger medium-wave broadcast stations, and a series-tuned LC circuit for each of the HF bands to provide some needed selectivity. Everything is wired together ugly-style in a metal enclosure, with a little jiggering needed to isolate the variable capacitor from ground.

The last two-thirds of the video below shows the helper in use on everything from the 11-meter (CB) band down to the AM bands. This would be a great addition to any ham’s SDR toolkit.

Recently China’s new CHIEF hypergravity facility came online to begin research projects after beginning construction in 2018. Standing for Centrifugal Hypergravity and Interdisciplinary Experiment Facility the name covers basically what it is about: using centrifuges immense acceleration can be generated. With gravity defined as an acceleration on Earth of 1 g, hypergravity is thus a force of gravity >1 g. This is distinct from simple pressure as in e.g. a hydraulic press, as gravitational acceleration directly affects the object and defines characteristics such as its effective mass. This is highly relevant for many disciplines, including space flight, deep ocean exploration, materials science and aeronautics.

While humans can take a g-force (g₀) of about 9 g₀ (88 m/s²) sustained in the case of trained fighter pilots, the acceleration generated by CHIEF’s two centrifuges is significantly above that, able to reach hundreds of g. For details of these centrifuges, this preprint article by [Jianyong Liu] et al. from April 2024 shows the construction of these centrifuges and the engineering that goes into their operation, especially the aerodynamic characteristics. Both air pressure (30 – 101 kPa) and arm velocity (200 – 1000 g) are considered, with the risks being overpressure and resonance, which if not designed for can obliterate such a centrifuge.

The acceleration of CHIEF is said to max out at 1,900 gravity tons (gt, weight of one ton due to gravity), which is significantly more than the 1,200 gt of the US Army Corps of Engineers’ hypergravity facility.

Tinkerers and tech enthusiasts, brace yourselves: the frontier of biohacking has just expanded. Picture implantable medical devices that don’t need batteries—no more surgeries for replacements or bulky contraptions. Though not all new (see below), ChemistryWorld recently shed new light on these innovations. It’s as exciting as it is unnerving; we, as hackers, know too well that tech and biology blend a fine ethical line. Realising our bodies can be hacked both tickles our excitement and unsettlement, posing deeper questions about human-machine integration.

Since the first pacemaker hit the scene in 1958, powered by rechargeable nickel-cadmium batteries and induction coils, progress has been steady but bound by battery limitations. Now, researchers like Jacob Robinson from Rice University are flipping the script, moving to designs that harvest energy from within. Whether through mechanical heartbeats or lung inflation, these implants are shifting to a network of energy-harvesting nodes.

From triboelectric nanogenerators made of flexible, biodegradable materials to piezoelectric devices tapping body motion is quite a leap. John Rogers at Northwestern University points out that the real challenge is balancing power extraction without harming the body’s natural function. Energy isn’t free-flowing; overharvesting could strain or damage organs. A topic we also addressed in April of this year.

As we edge toward battery-free implants, these breakthroughs could redefine biomedical tech. A good start on diving into this paradigm shift and past innovations is this article from 2023. It’ll get you on track of some prior innovations in this field. Happy tinkering, and: stay critical! For we hackers know that there’s an alternative use for everything!

Who doesn’t like dial-up internet? Even if those who survived the dial-up years are happy to be on broadband, and those who are still on dial-up wish that they weren’t, there’s definitely a nostalgic factor to the experience. Yet recreating the experience can be a hassle, with signing up for a dial-up ISP or jumping through many (POTS) hoops to get a dial-up server up and running. An easier way is demonstrated by [Minh Danh] with a Viking DLE-200B telephone line simulator in a recent blog post.

This little device does all the work of making two telephones (or modems) think that they’re communicating via a regular old POTS network. After picking up one of these puppies for a mere $5 at a flea market, [Minh Danh] tested it first with two landline phones to confirm that yes, you can call one phone from the other and hold a conversation. The next step was thus to connect two PCs via their modems, with the other side of the line receiving the ‘call’. In this case a Windows XP system was configured to be the dial-up server, passing through its internet connection via the modem.

With this done, a 33.6 kbps dial-up connection was successfully established on the client Windows XP system, with a blistering 3.8 kB/s download speed. The reason for 33.6 kbps is because the DLE-200B does not support 56K, and according to the manual doesn’t even support higher than 28.8 kbps, so even reaching these speeds was lucky.