Fixing A Dead Makita Battery With A 20 Cent Part

August 11, 2026 by No comments
That's not what an NTC should be reading. (Credit: The Repair Forge, YouTube)
That’s not what an NTC should be reading. (Credit: The Repair Forge, YouTube)

It’s no real secret that battery packs for power tools aren’t the foremost when it comes to user serviceability, so if said battery pack suddenly stops charging outside of warranty, you generally just e-waste it. That’s what [The Repair Forge] could have done for the Makita battery pack in question, but instead it was opened up for a diagnosis and fix.

Rather than the charger throwing up an error with this specific battery, it would flash its red LED and run its fan, but never actually start the charging process. Apparently the charger seems to think that the battery is either too hot or cold to be charged, which already gives a big hint as to what might be wrong.

Using the open source PocketOBI tool it’s possible to query the battery, which showed that one of the internal thermistors reported the battery being at a chilly -30°C while the other a more reasonable 28°C. After popping open the pack and measuring the thermistors, the faulty one registered as infinite resistance thus confirming that it had failed.

By putting in a temporary resistor this diagnosis was confirmed, thus the next step will be to replace said thermistor. This same procedure was then used with a second battery, whose thermistor read a wild 64°C.

Overall it’s a pretty easy fix, using a 20 cent part, with the entirety of diagnosis to repair taking maybe ten minutes when using a tool like PocketOBI, itself based on the great Open Battery Information project that originally reverse-engineered the Makita battery protocol.

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A man's hand is shown holding brass-colored tweezers. In the tweezers are held the inner race and the ball cage of a ball bearing, with half of the outer race lying below them on a table.

Splitting A Ball Bearing To Cut Out Backlash

August 11, 2026 by 2 Comments

Gears are usually the biggest contributors to backlash in a mechanical system, but they’re far from the only culprits. Ball bearings are a less obvious source of imprecision, since any gaps between the balls and the races can lead to axial wobble. Precision mechanisms can eliminate this by pairing two ball bearings, holding the outer races fixed, and applying a preload force to the inner traces. [Chronova Engineering], however, has a different solution, for which he split a ball bearing in half.

Besides taking up more room, thermal expansion also means that it’s difficult to apply a consistent preload force between two ball bearings. Instead, to make a self-contained preloaded bearing, [Chronova Engineering] first disassembled a single ball bearing. The most difficult part of this is taking apart the ball cage; the two parts of this are normally riveted together, but he managed to find a crimped cage and pry it apart. After taking the bearing completely apart, he cut the outer trace in half along the circumference, then reassembled the bearing. The split outer trace makes it possible to press the two halves together, preloading it and removing slop.

To see how well this worked, [Chronova Engineering] replaced the the ball bearing supporting one end of the feed screw for a milling machine with this new bearing. Before the replacement, it had a backlash of 0.1 to 0.2 millimeters; after the modification, it dropped to 30 to 40 microns. This kind of bearing is already known in the machining world – four-point-contact bearings use a very similar principle – but they don’t seem to be well known.

For more about these common yet remarkable rotary mechanisms, check out our article on bearings. If, on the other hard, precision isn’t a priority, you can always 3D print ball bearings.

Turning A Toy Game Boy Into A Real Game Boy

August 11, 2026 by 1 Comment

In the world of children’s toys there are many offerings which are meant to look like devices used by older kids or even adults, with the Fisher Price Laugh & Learn Lil’ Gamer toy bearing quite the resemblance to Nintendo’s iconic Game Boy. Although this factoid could be filed away as amusing trivia before passing said toy to a child for its requisite physical abuse by said child, a purported adult can still have a lot of fun with this toy by modding it into a real Game Boy, as [KOUZEX] recently did.

Part of the challenge here is to not just treat it as an unconventional replacement shell for a genuine Game Boy, but to retain as much of the child toy’s look and feel as possible. This includes things like buttons and even the weird sliding blocks on the side.

For the functional components a Game Boy Color with a busted screen was chosen as a donor, with the GBC mainboard fitting almost perfectly inside its new shell. Wires were then soldered to bridge Nintendo’s PCB with the toy’s PCB to make the original buttons and speaker work. After blowing a fuse on the GBC mainboard due to likely some power back feeding, the toy’s PCB had its non-essential parts stripped, but fortunately without further damage to the grafted in electronics.

Most of this mod is quite straightforward, just with some creativity required to add a Select and Start button as these were notably absent from the original. The new, rather large replacement OLED screen is a nice upgrade too and actually fits pretty well with the chunky look of the child’s toy. Even as mostly a joke mod, it seems surprisingly functional.

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The PC OS That Would Have Blown Your Mind Back In 1984

August 11, 2026 by 28 Comments

As far as desktop microcomputers for mere mortals went in the first half of the 1980s, there was a sharp distinction between home computers such as the many 8-bit machines we regularly see here, and what you might call professional computers such as a CP/M word-processor or the earliest IBM PCs. These were conservative machines, boring even, with command line interfaces and mostly text-mode software.

When the middle of the decade saw the arrival of mass-market machines such as the Macintosh or the Amiga with their beautiful GUIs, a PC with DOS couldn’t yet compete. [Jggonz] then is over four decades late with the beautiful os8088, a fully-functional OS for 8088 IBM PCs and clones, with a very slick Mac-style GUI.

os8088 is a single-floppy OS that provides preemptive multitasking and fully loadable software alongside that GUI, unlike other similar projects we’ve seen it’s not an all-in-one compiled application that just looks like an OS. There’s a second floppy with a suite of software that would have been seriously impressive back in the day, with games, graphics, and demos. It’s a shame that this thing appeared in 2026 when there is little need of it.

You can try it for yourself either on real hardware, your own emulator, or even in an in-browser emulator. Sadly it’s not OS enough to fulfill the requirements for a Daily Drivers test drive, but it’s definitely fun to play with. Bonus, if you run it on a Book8088.

PC-1: The 1954 Computer With No Tubes, Relays, Or Transistors

August 11, 2026 by 16 Comments

However you make a digital computer, you need something to represent a binary digit. Usually this is some form of switch: a relay, a tube, or a transistor, although there have been other ways to represent state. In 1954, [Eiichi Goto] of Japan invented the parametron, a resonant circuit using a ferrite core and a capacitor that could be moved between two phases.

According to [Goto’s] 1959 paper, the device is effectively a parametric oscillator, similar to some used at UHF frequencies by hams. The idea is that a tuned circuit is set to some frequency and driven with twice that frequency.

A What?

A parametron is essentially a resonant circuit made with inductors or capacitors whose reactance is varied at twice its resonant frequency. That “pumping” causes the circuit to oscillate at half the pump frequency. The neat trick is that there are two equally stable oscillation states at half the pump frequency, separated from each other by 180° of phase. Those two phases become binary 0 and 1. Depending on the incoming signals, one phase will win over the others.

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Running DOOM On A Cheap 104-in-One Handheld

August 11, 2026 by 4 Comments

Taking a break from putting DOOM on devices that absolutely were never conceived for use as gaming devices, [Aaron Christophel] recently got enticed by some cheapo handheld gaming systems at his local Action budget store. One is a controller-shaped ‘mini game console’ with 104 games from the 1980s and 1990s, while the other is simply a Pac-Man handheld in a more typical rectangular form factor. Although this brings to mind basic blob chips and limited hacking potential, as it turns out they’re actually quite nice inside.

As also covered in the demonstration video, rather than said nasty blob chip, both handhelds turned out to use the same unmarked MCU in QFN48 packaging. Some prodding and poking confirmed that it’s a typical ARM core, specifically a Cortex-M33 compatible STAR-MC1 ARMv8-M from an unknown manufacturer. Without a datasheet to go by, its limitations had to be discovered experimentally.

Of those, the biggest were a clock speed of 62 MHz – instead of the typical 194 MHz – as well as a lack of sound. This latter issue might be fixable with a better understanding of what appears to be a quirky DMA-fed DAC. Beyond this you’re also dealing with limited memory and of course just 4 MB of flash, though the chip for this might be upgradable if the MCU can map more. You do get a 320×240 display and a lot of buttons, which is admittedly nice.

As for the price difference of around $8/€7 for the Pac-Man version, this appears to be due to it running an officially licensed Bandai Namco arcade emulator as firmware, while the 104-in-one unit runs FlyThings/ZKSWE with a NES emulator.

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The Code The British Government Doesn’t Want You To See (Any More)

August 11, 2026 by 23 Comments

Governments like to do things which at least sound open and honest. It makes them look like Thoroughly Good Eggs, when maybe the truth might be a little murkier. They also like to quietly roll back those things when it suits them, and so it is that [Jonty], of Electromagnetic Field fame, has assembled a list of code repositories quietly disappeared by the UK Government. Naturally, being thorough about such things, he’s also kept copies.

Now we’re always happy to reach for a mildly sensational title, but paging through the archive it’s more a collection of flotsam and jetsam than a trove of state secrets, after all these were all public GitHub repositories. There’s a lot of web stuff, some data analytics in R for those interminable government reports, odd bits of server code, and a whole load more. The Met Office Informatics Lab in particular has a fair bit of climate related code and data.

Should Brits with an interest in government openness be concerned here? In terms of the data and code deleted, probably not, but in terms of that which they might delete without notice in the future, it’s a slippery slope. We’re glad people like [Jonty] are there to make these things a little less easy to disappear.