2026-02-18 11:00:45
Antenna design is often referred to as a black art or witchcraft, even by those experienced in the space. To that end, [Janne] wondered—could years of honed skill be replaced by bruteforcing the problem with the aid of some GPUs? Iterative experiments ensued.
[Janne]’s experience in antenna design was virtually non-existent prior to starting, having a VNA on hand but no other knowledge of the craft. Formerly, this was worked around by simply copying vendor reference designs when putting antennas on PCBs. However, knowing that sometimes a need for something specific arises, they wanted a tool that could help in these regards.
The root of the project came from a research paper using an FDTD tool running on GPUs to inversely design photonic nanostructures. Since light is just another form of radio frequency energy, [Janne] realized this could be tweaked into service as an RF antenna design tool. The core simulation engine of the FDTD tool, along with its gradient solver, were hammered into working as an antenna simulator, with [Janne] using LLMs to also tack on a validation system using openEMS, an open-source electromagnetic field solver. The aim was to ensure the results had some validity to real-world physics, particularly important given [Janne] left most of the coding up to large language models. A reward function development system was then implemented to create antenna designs, rank them on fitness, and then iterate further.
The designs produced by this arcane system are… a little odd, and perhaps not what a human might have created. They also didn’t particularly impress in the performance stakes when [Janne] produced a few on real PCBs. However, they do more-or-less line up with their predicted modelled performance, which was promising. Code is on Github if you want to dive into experimenting yourself. Experienced hands may like to explore the nitty gritty details to see if the LLMs got the basics right.
We’ve featured similar “evolutionary” techniques before, including one project that aimed to develop a radio. If you’ve found ways to creatively generate functional hardware from boatloads of mathematics, be sure to let us know on the tipsline!
2026-02-18 08:00:52
Cathode ray tubes (CRTs) are a fascinating display technology that has been largely abandoned outside of retro gaming and a few other niche uses. They use magnets to steer a beam of electrons rapidly across a screen, and while a marvel of engineering for their time, their expense, complexity, and weight all led to them being largely replaced by other displays like LCDs and LEDs. They were also difficult to miniaturize, but there were a few companies who tried. [dooglehead] located a few of the smallest CRT displays he could find and got to work putting them in the most unlikely of situations: a virtual reality headset.
The two displays for his headset come from Sony Watchmans, compact over-the-air black-and-white handheld televisions from the late 1900s. [dooglehead] had to create a method for sending video to these units which originally had no input connections, and then also used an FPGA to split a video signal into two parts, with one for each display. The two displays are placed side by side and attached to a Google Cardboard headset, with an off-the-shelf location tracker attached at the top. An IMU tracks head rotation while this location tracker tracks the motion of the unit through 3D space.
With everything assembled and ready to go, the CRT VR headset only weighs in a few grams heavier than [dooglehead]’s modern HTC headset, although it’s lacking a case (which is sorely needed to cover up the exposed high voltage of the CRTs). He reports surprisingly good performance, with notable interlacing and focus issues. He doesn’t plan to use it to replace any of his modern VR displays anytime soon, but it was an interesting project nonetheless. There are some rumors that CRTs are experiencing a bit of a revival, so we’d advise anyone looking to toss out an old CRT to at least put it on an online market place before sending it to a landfill.
2026-02-18 05:00:04
If you’re looking to jack up your car and you don’t have anything on hand, your 3D printer might not be the first tool you look towards. With that said, [Alan Reiner] had great success with a simple idea to create a surprisingly capable scissor jack with a multi-material print.
The design will look familiar if you’ve ever pulled the standard jack out of the back of your car. However, this one isn’t made fully out of steel. It relies on an M6 bolt and a rivet nut, but everything else is pure plastic. In this scissor jack design, rigid PETG arms are held in a scissor jack shape with a flexible TPU outer layer. Combined with the screw mechanism, it’s capable of delivering up to 400 pounds of force without failing. It’s an impressive figure for something made out of 80 grams of plastic. The idea came about because of [Alan’s] recent build of a RatRig VCore4 printer, which has independent dual extruders. This allowed the creation of single prints with both rigid and flexible filaments included.
[Alan] did test the jack by lifting up his vehicle, which it kind of achieved. The biggest problem was the short stroke length, which meant it could only raise the back of the car by a couple inches. Printing a larger version could make it a lot more practical for actual use… if you’re willing to trust a 3D-printed device in such use.
Files are on Printables if you wish to make your own. It’s worth paying attention to the warning upfront that [Alan] provides—”THIS CAN CREATE A LOT OF FORCE (400+ lbs!), WHICH MEANS IT CAN STORE A LOT OF ENERGY THAT MIGHT BE RELEASED SUDDENLY. Please be cautious using 3d-printed objects for high loads and wear appropriate safety equipment!”
Funnily enough, we’ve featured 3D printed jacks before, all the way back in 2015! Video after the break.
2026-02-18 03:30:51
An orrery is a beautiful type of mechanical contrivance, built to demonstrate the motion of heavenly objects. LEGO happens to offer just such a device, built using its Technic line of blocks, shafts, and gears. Only, it has a serious limitation—it has to be cranked manually to make it spin the Earth around the sun. [Görkem] set out to fix this glaring oversight with some good old-fashioned hardware.
The setup removes just five LEGO pieces from the original design, eliminating the hand crank from the mechanism. In its place, [Görkem] installed a NEMA 17 stepper motor, paired with a custom PCB mounted on the back. That carries an ESP32 microcontroller and a TMC2208 stepper motor driver set up for silent drive. Rigged up like so, the orrery can simulate the motion of the Earth and Moon around the Sun in real time. There’s also a knob to track back and forth in time, and a button to reset the system to the correct real-time position.
The final build looks great, combining the LEGO Technic parts with some chunky electronics and 7-segment displays that make it a wonderful techy desk decoration. Down the line, [Görkem] hopes to offer a plug-and-play kit to others who wish to duly animate their own LEGO orrery sets (set #42179).
We love a good LEGO build around these parts. We’ve featured everything from parts sorters to functional typewriters in the past.
2026-02-18 00:30:43
The ancient question of whether or not it’s possible to construct a circle with the same area as a given square using only a drawing compass and straightedge was finally answered in 1882, where it was proved that pi is a transcendental number, meaning it cannot be accurately represented in a compass-and-straightedge system. This inability to accurately represent pi is just one of the ways in which these systems resemble a computer, a similarity that [0x0mer] explored in CasNum.
The core of the program represents operations with a drawing compass and unmarked straightedge. There are only a few operations that can be used for calculation: constructing a line through two points, constructing a circle centered at one point and intersecting another point, and constructing the intersection(s) of two lines, a line and a circle, or two circles. An optional viewer visualizes these operations. Another class builds on top of this basic environment to perform arithmetic and logical operations, representing numbers as points in the Cartesian plane. To add two numbers, for example, it constructs the midpoint between them, then doubles the distance from the origin.
There are some examples available, including the RSA algorithm. [0x0mer] also altered a Game Boy emulator to implement the ALU instructions using compass and straightedge operations. In testing, it took about fifteen minutes to boot, and runs at a “totally almost playable” speed, near one FPS. This is after extensive caching has been applied to minimize computation time; the performance here is impressive, but in a more qualitative than quantitative sense.
Being virtual, this system is discrete, but a physical compass and straightedge form a simple analog computer capable of dealing with continuous values.
2026-02-17 23:00:59
Imagine a line of affordable toys controlled by the player’s brainwaves. By interpreting biosignals picked up by the dry electroencephalogram (EEG) electrodes in an included headset, the game could infer the wearer’s level of concentration, through which it would be possible to move physical objects or interact with virtual characters. You might naturally assume such devices would be on the cutting-edge of modern technology, perhaps even a spin-off from one of the startups currently investigating brain-computer interfaces (BCIs).
But the toys in question weren’t the talk of 2025’s Consumer Electronics Show, nor 2024, or even 2020. In actual fact, the earliest model is now nearly as old as the original iPhone. Such is the fascinating story of a line of high-tech toys based on the neural sensor technology developed by a company called Neurosky, the first of which was released all the way back in 2009.
Yet despite considerable interest leading up to their release — fueled at least in part by the fact that one of the models featured Star Wars branding and gave players the illusion of Force powers — the devices failed to make any lasting impact, and have today largely fallen into obscurity. The last toy based on Neurosky’s technology was released in 2015, and disappeared from the market only a few years later.
I had all but forgotten about them myself, until I recently came across a complete Mattel Mindflex at a thrift store for $8.99. It seemed a perfect opportunity to not only examine the nearly 20 year old toy, but to take a look at the origins of the product, and find out what ultimately became of Neurosky’s EEG technology. Was the concept simply ahead of its time? In an era when most people still had flip phones, perhaps consumers simply weren’t ready for this type of BCI. Or was the real problem that the technology simply didn’t work as advertised?
NeuroSky was founded in 1999 to explore commercial applications for BCIs, and as such, they identified two key areas where they thought they could improve upon hardware that was already on the market: cost, and ease of use.
Cost is an easy enough metric to understand and optimize for in this context — if you’re trying to incorporate your technology into games and consumer gadgets, cheaper is better. To reduce costs, their hardware wasn’t as sensitive or as capable as what was available in the medical and research fields, but that wasn’t necessarily a problem for the sort of applications they had in mind.
Of course, it doesn’t matter how cheap you make the hardware if manufacturers can’t figure out how to integrate it into their products, or users can’t make any sense of the information. The average person certainly wouldn’t be able to make heads or tails of the raw data coming from electroencephalography or electromyography sensors, and the engineers looking to graft BCI features into their consumer products weren’t likely to do much better.
To address this, NeuroSky’s technology presented the user with simple 0 to 100 values for more easily conceptualized parameters like concentration and anxiety based on their alpha and beta brainwaves. This made integration into consumer devices far simpler, albeit at the expense of accuracy and flexibility. The user could easily see when values were going up and down, but whether or not those values actually corresponded with a given mental state was entirely up to the interpretation being done inside the hardware.
These values were easy to work with, and with some practice, NeuroSky claimed the user could manipulate them by simply focusing their thoughts. So in theory, a home automation system could watch one of these mental parameters and switch on the lights when the value hit a certain threshold. But the NeuroSky BCI could never actually sense what the user was thinking — at best, it could potentially determine how hard an individual was concentrating on a specific thought. Although in the end, even that was debatable.
After a few attempted partnerships that never went anywhere, NeuroSky finally got Mattel interested in 2009. The result was the Mindflex, which tasked the player with maneuvering a floating ball though different openings. The height of the ball, controlled by the speed of the blower motor in the base of the unit, was controlled by the output of the NeuroSky headset. Trying to get two actionable data points out of the hardware was asking a bit much, so moving the ball left and right must be done by hand with a knob.
But while the Mindflex was first, the better known application for NeuroSky’s hardware in the entertainment space is certainly the Star Wars Jedi Force Trainer released by Uncle Milton a few months later. Fundimentally, the game worked the same way as the Mindflex, with the user again tasked with controlling the speed of a blower motor that would raise and lower a ball.
But this time, the obstacles were gone, as was the need for a physical control. It was a simpler game in all respects. Even the ball was constrained in a clear plastic tube, rather than being held in place by the Coandă effect as in the Mindflex. In theory, this made for a less distracting experience, allowing the user to more fully focus on trying to control the height of the ball with their mental state.
But the real hook, of course, was Star Wars. Uncle Milton cleverly wrapped the whole experience around the lore from the films, putting the player in the role of a young Jedi Padawan that’s using the Force Trainer to develop their telekinetic abilities. As the player attempted to accurately control the movement of the ball, voice clips of Yoda would play to encourage them to concentrate harder and focus their minds on the task at hand. Even the ball itself was modeled after the floating “Training Remote” that Luke uses to practice his lightsaber skills in the original film.
The Force Trainer enjoyed enough commercial success that Uncle Milton produced the Force Trainer II in 2015. This version used a newer NeuroSky headset which featured Bluetooth capability, and paired it with an application running on a user-supplied Android or Apple tablet. The tablet was inserted into a base unit which was able to display “holograms” using the classic Pepper’s Ghost illusion. Rather than simply moving a ball up and down, the young Jedi in training would have to focus their thoughts to virtually lift a 3D model of an X-Wing out of the muck or knock over groups of battle droids.
Unfortunately, Force Trainer II didn’t end up being as successful as its predecessor, and was discontinued a few years later. Even though the core technology was the same as in 2009, the reviews I can still find online for this version of the game are scathing. It seems like most of the technical problems came from the fact that users had to connect the headset to their own device, which introduced all manner of compatibility issues. Others claimed that the game doesn’t actually read the player’s mental state at all, and that the challenges can be beaten even if you don’t wear the headset.
The headsets for both the Mindflex and the original Force Trainer use the same core hardware, and NeuroSky even released their own “developer version” of the headset not long after the games hit the market which could connect to the computer and offered a free SDK.
Over the years, there have been hacks to use the cheaper Mindflex and Force Trainer headsets in place of NeuroSky’s developer version, some of which have graced these very pages. But somehow we missed what seems to be the best source of information: How to Hack Toy EEGs. This page not only features a teardown of the Mindflex headset, but shows how it can be interfaced with the Arduino so brainwave data can be read and processed on the computer.
I haven’t gone too far down this particular rabbit hole, but I did connect the headset up to my trusty Bus Pirate 5 and could indeed see it spewing out serial data. Paired with a modern wireless microcontroller, the Mindflex could still be an interesting device for BCI experimentation all these years later. Though if you can pick up the Bluetooth Force Trainer II headset for cheap on eBay, it sounds like it would save you the trouble of having to hack it yourself.
So the big question: does the Mindflex, and by extension NeuroSky’s 2009-era BCI technology, actually work?
Before writing this article, I spent the better part of an hour wearing the Mindflex headset and trying to control the LEDs on the front of the device that are supposed to indicate your focus level. I can confidently say that it’s doing something, but it’s hard to say what. I found that getting the focus indicator to drop down to zero was relatively easy (story of my life) and nearly 100% repeatable, but getting it to go in the other direction was not as consistent. Sometimes I could make the top LEDs blink on and off several times in a row, but then seconds later I would lose it and struggle to light up even half of them.
Some critics have said that the NeuroSky is really just detecting muscle movement in the face — picking up not the wearer’s focus level so much as a twitch of the eye or a furrowed brow which makes it seem like the device is responding to mental effort. For what it’s worth, the manual specifically says to try and keep your face as still as possible, and I couldn’t seem to influence the focus indicator by blinking or making different facial expressions. Although if it actually was just detecting the movement of facial muscles, that would still be a neat trick that offered plenty of potential applications.
I also think that a lot of the bad experiences people have reported with the technology is probably rooted in their own unrealistic expectations. If you tell a child that a toy can read their mind and that they can move an object just by thinking about it, they’re going to take that literally. So when they put on the headset and the game doesn’t respond to their mental image of the ball moving or the LEDs lighting up, it’s only natural they would get frustrated.
So what about the claims that the Force Trainer II could be played without even wearing the headset? If I had to guess, I would say that if there’s any fakery going on, it’s in the game itself and not the actual NeuroSky hardware. Perhaps somebody was worried the experience would be too frustrating for kids, and goosed the numbers so the game could be beaten no matter what.
As for NeuroSky, they’re still making BCI headsets and offer a free SDK for them. You can buy their MindWave Mobile 2 on Amazon right now for $130, though the reviews aren’t exactly stellar. They continue to offer a single chip EEG sensor (datasheet, PDF) that you can integrate into your projects as well, the daughterboard for which looks remarkably similar to what’s in the Mindflex headset. Despite the shaky response to the devices that have hit the market so far, it seems that NeuroSky hasn’t given up on the dream of bringing affordable brain-computer interfaces to the masses.
