Fixing An Unpleasant SD Card Slot Issue In A NanoVNA

March 9, 2025 by 9 Comments

SD cards & the much smaller microSD cards are found on many devices, with the card often accessible from outside the enclosure. Unfortunately there’s a solid chance that especially small microSD cards will find their way past the microSD card reader slot and into the enclosure. This is what happened to [Rob] of the SevenFortyOne Radios and Repairs channel on YouTube with a NanoVNA unit. While shaking the unit, you can clearly hear the microSD card rattling inside, courtesy of the rather large gap above the card slot.

After a quick teardown and extracting the lost microSD card, the solution to prevent this is a simple bit of foam stuck on top of the microSD card slot, so that the too large opening in the enclosure is now fully blocked. It’s clearly a bit of a design fail in this particular NanoVNA unit, worsened by the tiny size of the card and having to use a fingernail to push the card into the slot as it’s so far inside the enclosure.

While [Rob] seems to blame himself for this event, we’d chalk it mostly up to poor design. It’s an issue that’s seen with certain SBC enclosures and various gadgets too, where losing a microSD card is pretty much a matter of time, and hugely fiddly at the best of times. That said, what is your preferred way of handling microSD card insertion & removal in devices like these?

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ice forming on surface with plus and minus pole

The Coolest Batteries You’ve Never Heard Of

March 9, 2025 by 55 Comments

Imagine cooling your building with the same principle that kept Victorian-era icehouses stocked with lake-frozen blocks, but in modern form. That’s the idea behind ice batteries, a clever energy storage hack that’s been quietly slashing cooling costs across commercial buildings. The invention works by freezing water when energy is cheap, and using that stored cold later, they turn major power hogs (air conditioning, we’re looking at you) into more efficient, cost-effective systems.

Pioneers like Nostromo Energy and Ice Energy are refining the tech. Nostromo’s IceBrick modules pack 25 kWh of cooling capacity each, install on rooftops, and cost around $250 per kWh—about half the price of lithium-ion storage. Ice Energy’s Ice Bear 40 integrates with HVAC systems, shifting up to 95% of peak cooling demand to off-peak hours. And for homes, the Ice Bear 20 replaces traditional AC units while doubling as a thermal battery.

Unlike lithium-ion, ice batteries don’t degrade chemically – their water is endlessly reusable. Combining the technology with this hack, it’s even possible in environments where water is scarce. But the trade-off? They only store cooling energy. No frozen kilowatts for your lightbulbs, just an efficient way to handle the biggest energy drain in most buildings.

Could ice batteries help decentralize energy storage? They’re already proving their worth in high-demand areas like California and Texas. Read the full report here and let us know your thoughts in the comments.

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Retrotechtacular: Better Living Through Nuclear Chemistry

March 8, 2025 by 11 Comments

The late 1950s were such an optimistic time in America. World War II had been over for less than a decade, the economy boomed thanks to pent-up demand after years of privation, and everyone was having babies — so many babies. The sky was the limit, especially with new technologies that promised a future filled with miracles, including abundant nuclear power that would be “too cheap to meter.”

It didn’t quite turn out that way, of course, but the whole “Atoms for Peace” thing did provide the foundation for a lot of innovations that we still benefit from to this day. This 1958 film on “The Armour Research Reactor” details the construction and operation of the world’s first privately owned research reactor. Built at the Illinois Institute of Technology by Atomics International, the reactor was a 50,000-watt aqueous-homogenous design using a solution of uranyl sulfate in distilled water as its fuel. The core is tiny, about a foot in diameter, and assembled by hand right in front of the camera. The stainless steel sphere is filled with 90 feet (27 meters) of stainless tubing to circulate cooling water through the core. Machined graphite reflector blocks surrounded the core and its fuel overflow tank (!) before the reactor was installed in “biological shielding” made from super-dense iron ore concrete with walls 5 feet (1.5 m) thick — just a few of the many advanced safety precautions taken “to ensure completely safe operation in densely populated areas.”

While the reactor design is interesting enough, the control panels and instrumentation are what really caught our eye. The Fallout vibe is strong, including the fact that the controls are all right in the room with the reactor. This allows technicians equipped with their Cutie Pie meters to insert samples into irradiation tubes, some of which penetrate directly into the heart of the core, where neutron flux is highest. Experiments included the creation of radioactive organic compounds for polymer research, radiation hardening of those new-fangled transistors, and manufacturing radionuclides for the diagnosis and treatment of diseases.

This mid-century technological gem might look a little sketchy to modern eyes, but the Armour Research Reactor had a long career. It was in operation until 1967 and decommissioned in 1972, and similar reactors were installed in universities and private facilities all over the world. Most of them are gone now, though, with only five aqueous-homogenous reactors left operating today.

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Fictional Computers: EMERAC Was The Chatbot Of 1957

March 8, 2025 by 17 Comments

Movies mirror the time they were made. [ErnieTech] asserts that we can see what people thought about computers back in 1957 by watching the classic Spencer Tracy/Katharine Hepburn movie “Desk Set.” What’s more, he thinks this might be the first movie appearance of a human-like computer. On a side note, in the UK this movie was known as “The Other Woman.”

The story is about an MIT computer expert computerizing a broadcasting company who, of course, finds romance and, at least towards the end, comedy.

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Writing An OLED Display Driver In MicroZig

March 8, 2025 by 18 Comments

Although most people would use C, C++ or MicroPython for programming microcontrollers, there are a few more obscure options out there as well, with MicroZig being one of them. Recently [Andrew Conlin] wrote about how to use MicroZig with the Raspberry Pi RP2040 MCU, showing the process of writing an SSD1306 OLED display driver and running it. Although MicroZig has since published a built-in version, the blog post gives a good impression of what developing with MicroZig is like.

Zig is a programming language which seeks to improve on the C language, adding memory safety, safe pointers (via option types), while keeping as much as possible of what makes C so useful for low-level development intact. The MicroZig project customizes Zig for use in embedded projects,  targeting platforms including the Raspberry Pi MCUs and STM32.  During [Andrew]’s usage of MicroZig it was less the language or supplied tooling that tripped him up, and more just the convoluted initialization of the SSD1306 controller, which is probably a good sign. The resulting project code can be found on his GitHub page.

Expensive Camera, Cheap 3D-Printed Lens

March 8, 2025 by 8 Comments

If you’re a photography enthusiast, you probably own quite a few cameras, but the chances are your “good” one will have interchangeable lenses. Once you’ve exhausted the possibilities of the kit lens, you can try different focal lengths and effects, but you’ll soon find out that good glass isn’t cheap. Can you solve this problem by making your own lenses? [Billt] has done just that.

Given some CAD skills, it’s possible to replicate the mount on an existing lens, but he takes a shortcut by using a readily available camera cap project. There are two lenses detailed in the video below the break; the first is a plastic lens from a disposable camera, while the second takes one from a Holga toy camera. The plastic lens is inserted mid-print, giving the colour aberrations and soft focus you’d expect, while the Holga lens is mounted on a slide for focusing. There may be some room for improvement there, but the result is a pair of fun lenses for experimentation for not much outlay. Given the number of broken older cameras out there, it should be relatively easy for anyone wanting to try this for themselves to have a go.

The video is below the break, but while you’re on this path, take a look at a previous project using disposable camera lenses. Or, consider printing an entire camera.

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Transceiver Reveals Unusual Components

March 8, 2025 by 22 Comments

[MSylvain59] likes to tear down old surplus, and in the video below, he takes apart a German transceiver known as a U-600M. From the outside, it looks like an unremarkable gray box, especially since it is supposed to work with a remote unit, so there’s very little on the outside other than connectors. Inside, though, there’s plenty to see and even a few surprises.

Inside is a neatly built RF circuit with obviously shielded compartments. In addition to a configurable power supply, the radio has modules that allow configuration to different frequencies. One of the odder components is a large metal cylinder marked MF450-1900. This appears to be a mechanical filter. There are also a number of unusual parts like dogbone capacitors and tons of trimmer capacitors.

The plug-in modules are especially dense and interesting. In particular, some of the boards are different from some of the others. It is an interesting design from a time predating broadband digital synthesis techniques.

While this transceiver is stuffed with parts, it probably performs quite well. However, transceivers can be simple. Even more so if you throw in an SDR chip.

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