Growing Aluminium-Copper Alloy Crystals Using Hydrogen

April 20, 2026 by Maya Posch 2 Comments

Having molten aluminium interact with atmospheric water forms a source of hydrogen which can be rather problematic if you’re trying to cast aluminium parts. As the molten metal cools down, the dissolved hydrogen is forced out, creating bubbles and other flaws that make aluminium foundries rather upset. While you can inject inert gases to solve the problem, you can also lean into this issue to make some rather fascinating aluminium crystals and geodes, as [Electron Impressions] recently did.

The key here is to use a eutectic Al-Cu alloy at around 45% Cu by weight, as this alloy readily forms large crystals as it cools down. With hydrogen injected into the molten metal, this hydrogen forms large bubbles inside the cooling metal with crystals clearly visible.

A way to create proper geodes involves very slow cooling and pouring off the still molten metal before the eutectic point is reached. As can be seen in this video, this creates a rather impressive looking geode after it’s been smashed open. This also gives a good clue as to how these geological features form in nature, although one does not typically observe Al-Cu alloy geodes in the wild.

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Making The Most Pick-Proof Lock Yet

April 20, 2026 by Maya Posch 43 Comments

3D cutaway of the lock with the handle engaging the cog that rotates the mechanism. (Credit: Works By Design, YouTube)

Throughout the centuries the art of lock-making and lock-picking have been trapped in a constant struggle, with basic lock designs being replaced by ever more complex ones that seek to thwart any lockpicking attempts, as well as less gentle approaches. When it comes to the very common pin-and-tumbler lock design, the main issue here is that the keyway also provides direct access to the lock’s mechanism. This led [Works By Design] to brainstorm a lock design in which the keyway is hidden.

The ingenious part here is that because the actual key is rotated away after insertion, there is no clear path to the pins. This did require some creative thinking to have a somewhat traditional style key as well as a way to turn the internal mechanism so that the key would be pressed against the pins. Here inspiration was drawn from the switchable magnet mechanism as seen with e.g. magnetic bases. This ensures the key and key handle can be detached and attached quite firmly.

After many 3D printed prototypes, a metal version was CNCed and subjected to some early testing by a locksmith, who even with having seen the CAD model of the lock was stumped. With this initial result and some user feedback in the bag, it was time for large-scale testing with more lockpick enthusiasts, as there are many more ways to open a lock beyond pushing pins. That said, a mechanism was also added to the lock to prevent bumping attacks.

The next testers were found in the Lock Pickers United community, one of whom raised the issue of an impressioning attack. With a couple of test locks on their way to said lockpicking enthusiasts it’ll be exciting to see whether this new lock design will set the standard for future locks or not.

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DIY Nuclear Battery With PV Cells And Tritium

April 20, 2026 by Maya Posch 21 Comments

Nuclear batteries are pretty simple devices that are conceptually rather similar to photovoltaic (PV) solar, just using the radiation from a radioisotope rather than solar radiation. It’s also possible to make your own nuclear battery, with [Double M Innovations] putting together a version that uses standard PV cells combined with small tritium vials as radiation source.

The PV cells are the amorphous type, rated for 2.4 V, which means that they’re not too fussy about the exact wavelength at the cost of some general efficiency. You generally find these on solar-powered calculators for this reason. Meanwhile the tritium vials have an inner coating of phosphor so they glow. With a couple of these vials sandwiched in between two amorphous cells you thus have technically something that you could call a ‘nuclear battery’.

With an approximately 12 year half-life, tritium isn’t amazingly radioactive and thus the glow from the phosphor is also not really visible in daylight. With this DIY battery wrapped up in aluminium foil to cover it up fully, it does appear to generate some current in the nanoamp range, with a single-cell and series voltage of about 0.5 V.

A 170 VAC-rated capacitor is connected to collect some current over time, with just under 3 V measured after a night of charging. In how far the power comes from the phosphor and how much from sources like thermal radiation is hard to say in this setup. However, if you can match up the PV cell’s bandgap a bit more with the radiation source, you should be able to pull at least a few mW from a DIY nuclear battery, as seen with commercial examples.

This isn’t the first time we’ve seen this particular trick. A few years ago, a similar setup was used to power a handheld game, as long as you don’t mind waiting a few months for it to charge.

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Fixing A GameCube’s Dodgy Optical Drive With Fresh Capacitors

April 17, 2026 by Maya Posch 3 Comments

Generally when a game console with an optical drive stops reading discs the first thing that people do is crank on the potentiometer that controls the power to the laser diode to ramp up its output. While this can be a necessary solution to eke out a bit more life out of a clearly dying laser diode, this can actually massively shorten the lifespan of a good diode that’s just held back by bad capacitors. This is demonstrated by [Skawo] with a fix on a GameCube that stopped reading discs.

While it’s absolutely true that laser diodes have a limited lifespan, so do the capacitors and other components in the system. Thus, after tearing down this Japanese GameCube, [Skawo] accesses the optical PCB for some delicate plier-based capacitor surgery. One can absolutely question such violence, as well as the replacement mix of MLCC ceramics and a stray THT electrolytic capacitor, but the results after reassembly are obvious.

Without having to adjust the laser diode’s potentiometer, the game console now happily reads the game disc while the laser diode breathes a sigh of relief. Although all GameCube consoles will face the inevitable demise of their optical drives – barring a replacement optical pickup solution appearing – with this capacitor replacement solution it’s at least possible to stave off that undesirable time for a bit longer.

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Making A Bronze Mirror From Scratch

April 17, 2026 by Maya Posch 18 Comments

Although modern-day silvered glass mirrors have pretty much destroyed the market for bronze mirrors, these highly polished pieces of metal once were the pinnacle of mirror technology. Due to the laborious process required these mirrors saw use essentially only by the affluent. That said, how hard would it be to make a bronze mirror today with all of the modern technologies that even a hobbyist can acquire for their shed? Cue [Lundgren Bronze Studios] giving it a shot, starting by casting something flat-ish to start polishing.

Just getting that initial shape to start polishing is a chore, with hammering out the shape possibly being also a viable method. When casting metal it’s tricky to avoid having air bubbles and other defects forming, though using a sand mold seems to help a lot.

After you have the rough shape, polishing using power tools seems like cheating, but as you can see in the video even going from 50 to 8000 grit with a rotating disc left countless scratches. Amusingly, hand sanding did a much better job of removing the worst scratches, following which a polishing compound helped to bring out that literal mirror finish.

A quick glance at the Wikipedia entry for bronze mirrors shows that a tin-bronze alloy like speculum metal was used for thousands of years as it was much easier to polish to a good mirror finish. The metallurgy of what may seem like just a vanity item clearly goes deeper than just polishing up a metal surface.

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Comparing 12 VDC Air Fryers With Regular 240 VAC Ones

April 16, 2026 by Maya Posch 18 Comments

That boiling water is a contentious topic of discussion is clear, but what about hot air? When you take a 12 VDC, 280 Watt-rated air fryer and pit it against a bog-standard 240 VAC, 1400 Watt unit, which one would you want to use when you’re doing some camping or other exciting off-the-grid opportunities? Unlike with boiling water the physics aren’t as clear-cut here, so [Cahn] did some testing to figure out exactly what the efficiency numbers look like

Since air fryers rely on the transfer of thermal energy from the resistive heating element into the food, any thermal energy that’s not immediately transferred is effectively wasted. This, combined with the relatively low power rating and thus much higher time demand of the low-voltage air fryer is enough to set one’s expectations pretty low.

As scientific test samples chicken nuggets were used with the test, following a preheating period for the 12 VDC unit. Both units managed to hit a safe temperature inside the nuggets after 20 minutes, thus successfully staving off food poisoning, but the browning with the 240 VAC air fryer was much better.

As for the efficiency, the 12 VDC unit required 150 Wh for 20 minutes plus the 10 minutes of preheating, with 45 minutes total at 225 Watt to get proper browning. Meanwhile the 240 VAC unit burned through 250 Wh in 20 minutes, with no pre-heating, though only 230 Wh with no inverter losses included. As a final test, the 12 VDC unit was run at 400 Watt using 14.6 VDC input, which did indeed get it up to temperature much faster.

Thus both are equivalent, just with the caveat that the low-voltage unit will take considerably more time to get the same result. This mirrors the results with boiling water, where most options mostly vary in how much time they require to get water up to a boiling temperature.

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Do We Really Need Another Development Board?

April 16, 2026 by Maya Posch 34 Comments

It’s fair to say that there are a lot of development board form factors for MCUs, with [Tech Dregs] over on yonder YouTube on the verge of adding another one to the pile, but not before he was having some serious thoughts on the implications of such a decision. Does this world really need another devboard with the ubiquitous 2.54 mm (0.1″) pitch pin headers, all so that it can perhaps be used in the same traditional 2.54 mm pitch breadboards?

The thought that [Tech Dregs] is playing with is to go for something more akin to the system-on-module (SoM) approach that’s reminiscent of the Raspberry Pi compute module form factor. This means using a 1 mm pitch for the headers and castellated edges in case you want use it as an SMT part, while breaking out many more pins of the onboard ESP32 module in far less space.

Obviously, the main advantage of this approach is that much like with compute modules you can leave most of the tedious cheap stuff on a carrier board, while the expensive to manufacture components are on a self-contained module. Meanwhile with the much finer pitch on the SoM contacts it’d straddle the divide between a 2.54 mm breadboard-capable devboard and a fully custom PCB, while making any mistakes on the carrier board much cheaper to redo.

The counterpoint here is of course that something like an ESP32 module is already a module with a finer pitch, but if you need more than just what it offers, or you want to use an STM32 or RP MCU across boards it could make a lot of sense.

Having 1 mm pitch breadboards would honestly also be rather nifty, natch. That said, what are your thoughts on this matter?

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