An animated set of circles and lines are drawn on a black screen. Meanwhile, in a smaller window in the lower right corner, the boot screen of a Game Boy is displayed.

Running Pokémon With A Compass And Straightedge

February 17, 2026 by 1 Comment

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.

The Complicated Legacy Of Mind Controlled Toys

February 17, 2026 by 4 Comments

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?

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AirTag Has Hole Behind The Battery? It’s Likely Been Silenced

February 17, 2026 by 17 Comments

Apple AirTags have speakers in them, and the speaker is not entirely under the owner’s control. [Shahram] shows how the speaker of an AirTag can be disabled while keeping the device watertight. Because AirTags are not intended to be opened or tampered with, doing so boils down to making a hole in just the right place, as the video demonstrates.

By making a hole in just the right place, the speaker can be disabled while leaving water resistance intact.

How does putting a hole in the enclosure not compromise water resistance? By ensuring the hole is made in an area that is already “inside” the seal. In an AirTag, that seal is integrated into the battery compartment.

Behind the battery, the enclosure has a small area of thinner plastic that sits right above the PCB, and in particular, right above the soldered wire of the speaker. Since this area is “inside” the watertight seal, a hole can be made here without affecting water resistance.

Disabling the speaker consists of melting through that thin plastic with a soldering iron then desoldering the (tiny) wire and using some solder wick to clean up. It’s not the prettiest operation, but there are no components nor any particularly heat-sensitive bits in that spot. The modification has no effect on water resistance, and isn’t even visible unless the battery is removed.

In the video below, [Shahram] uses a second generation AirTag to demonstrate the mod, then shows that the AirTag still works normally while now being permanently silenced.

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Using 3D Printed Breadboards To Accommodate Wide Boards

February 17, 2026 by 25 Comments

Although off-the-shelf breadboards are plentiful and cheap, they almost always seem to use the same basic design. Although you can clumsily reassemble most of them by removing the voltage rail section and merging a few boards together, wouldn’t it be nice if you had a breadboard that you could stick e.g. one of those wide ESP32 development boards onto and still have plenty of holes to poke wires and component leads into? Cue [Ludwin]’s 3D printable breadboard design that adds a big hole where otherwise wasted contact holes would be.

The related Instructables article provides a visual overview of the rationale and the assembly process. Obviously only the plastic shell of the breadboard is printed, after which the standard metal contacts are inserted. These contacts can be ‘borrowed’ from commercial boards, or you can buy the contacts separately.

For the design files there is a GitHub repository, with breadboard designs that target the ESP32, Raspberry Pi Pico, and the Arduino Nano. An overview of the currently available board designs is found on the Hackaday.io project page, with the top image showing many of them. In addition to the single big space design there are also a few variations that seek to accommodate just about any component and usage, making it rather versatile.

Performing An Autopsy On 15 Dead Battle Born LFP Batteries

February 16, 2026 by 11 Comments

More molten plastic spacers between the bus bar and terminal. (Credit: Will Prowse)
More molten plastic spacers between the bus bar and terminal. (Credit: Will Prowse)

Because size matters when it comes to statistics, [Will Prowse] decided to not just bank on his handful of failed Battle Born LFP batteries when it came to documenting their failure modes. Instead he got a whole gaggle of them from a viewer who had experienced failures with their Battle Born LFP batteries for an autopsy, adding a total of 15 samples to the data set.

Interestingly, the symptoms of these dead batteries are all over the place, from a refusal to charge, some have the overheating terminal, some do not show any sign of life, others have charged cells but a non-responsive BMS, etc. As [Will] notes, it’s important to test batteries with a load and a charger to determine whether they are functional not just whether you can measure a charge.

Although some of the batteries still showed enough signs of life to be put aside for some load testing, the remaining ones were cut open to check their insides. This revealed the typical molten plastic at the terminals, but also a lot of very loose connections for the internal wiring. Another battery showed signs of corrosion inside, which could be due to either moisture intrusion or a cell having leaked its electrolyte.

While the full results will hopefully be released soon, the worrying thing about this latest batch of Battle Born LFP batteries is that they span quite a few years, with one being from 2018. Although it’s comforting that not every one of these batteries is necessarily going to catch on fire within its approximate 8-year lifespan, a lot seems to depend on exactly how you load and charge them, as [Will] is trying to figure out with the upcoming load testing. With the unit that he recently purchased for testing it turned out that lower currents actually made the melting problem much worse.

Between this video and the much awaited follow-up, [Will] actually got his hands on a troubled 300A-rated industrial Battle Born battery. During testing that one actually failed violently with a cell venting and the loose BMS rattling around in the case.

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What The FDA’s 2026 Wellness Device Update Means For Wearables

February 16, 2026 by 7 Comments

With more and more sensors being crammed into the consumer devices that many of us wear every day, the question of where medical devices begin and end, and how they should be regulated become ever more pertinent. When a ‘watch’ no longer just shows the time, but can keep track of a dozen vital measurements, and the line between ‘earbud’ and ‘hearing aid’ is a rather fuzzy one, this necessitates that institutions like the US FDA update their medical device rules, as was done recently in its 2026 update.

This determines how exactly these devices are regulated, and in how far their data can be used for medical purposes. An important clarification made in the 2026 update is the distinction between ‘medical information’ and ‘signals/patterns’. Meaning that while a non-calibrated fitness tracker or smart watch does not provide medically valid information, it can be used to detect patterns and events that warrant a closer look, such as indications of arrhythmia or low blood oxygen saturation.

As detailed in the IEEE Spectrum article, these consumer devices are thus  ‘general wellness’ devices, and should be marketed as such, without embellished claims. Least of all should they be sold as devices that can provide medical information.

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A Basic Guide To Shielding

February 16, 2026 by 2 Comments

[GreatScott] has recently been tinkering in the world of radio frequency emissions, going so far as to put their own designs in a proper test chamber to determine whether they meet contemporary standards for noise output. This led them to explore the concept of shielding, and how a bit of well-placed metal can make all the difference in this regard.

The video focuses on three common types of shielding—absorber sheets, shielding tapes, and shielding cabinets. A wide variety of electronic devices use one or more of these types of shielding. [GreatScott] shows off their basic effectiveness by putting various types of shielding in between a noise source and a near-field probe hooked up to a receiver. Just placing a bit of conductive material in between the two can cut down on noise significantly. Then, a software defined radio (SDR) was busted out for some more serious analysis. [GreatScott] shows how Faraday cages (or simple shielding cabinets] can be used to crush down spurious RF outputs to almost nothing, and how his noisy buck-boost designs can be quieted down with the use of the right absorber sheets that deal well with the problematic frequencies in question. The ultimate upshot of the tests is that higher frequencies respond best to conductive shielding that is well enclosed, while lower frequency noise benefits from more absorptive shielding materials with the right permeability for the job.

Shielding design can be a complex topic that you probably won’t master in a ten minute YouTube video, but this content is a great primer if you’re new to the topic. We’ve covered the topic before, too, particularly on how a bit of DIY shielding can really aid a cheap SDR’s performance. Video after the break.

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