Making A Copper-Oxide Photodetector From Scratch

September 20, 2026 by No comments

Photodetectors come in a wide variety of constructions and materials, with the Cu2O-based photodetector that [Mad Scientist Creations] demonstrates in a recent video being a good example of a photodetector that can be created at home using nothing but some copper and a heat source.

Of the two copper elements in a salt water cell, one element is heated to the point where a copper oxide layer forms, specifically Cu2O, which acts as a semiconductor and provides the photosensitive layer. Even a fairly crude sensor created with a regular gas stove produces enough of a current that it can be used in a simple light detection circuit.

Although copper-oxide photodetectors may seem quaint, they are getting a lot of interest as they feature a very narrow bandgap at 1.2 eV. In a 2019 study by [Hyeon-Joo Song] et al. as published in Scientific Reports such a sensor is enhanced with an optimized grain structure that improves its performance, with much higher sensitivity and faster response times.

As demonstrated by [Andrzej Kwiatkowski] et al. in a 2024 paper in Solar Energy Materials and Solar Cells these copper-oxide sensors can also be used for gas detectors, though they used advanced gas deposition to produce the thin films instead of sticking a bit of copper tape into a natural gas flame.

Even if DIY copper-oxide sensors aren’t quite as exciting as what one can do with access to a well-equipped (semiconductor) lab, it’s still a pretty accessible material that lends itself for easy experimentation.

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Hackaday Links: September 20, 2026

September 20, 2026 by 4 Comments

Some sad news to start this week off — after 52 years in business, Sherline has announced they are winding down their manufacturing operations. By the end of October they estimate they’ll have produced their last tool, and although they will no longer be making new products, they plan on supporting their existing customers for as long as possible. Although from the sound of the press release, that may mean simply keeping the website up and selling through their inventory of spare parts.

The company offered a range of American-made miniature lathes and mills, and while their manual machines may have been better known in our community, they did eventually branch out into CNC. The press release doesn’t go into a lot of detail about the chain of events that led up to this decision, but it does mention the challenges of modern manufacturing and the lingering aftereffects of the COVID pandemic.

At first blush, it might seem strange that the company would falter just as desktop CNCs appear to finally be gaining momentum, but of course that doesn’t change their ability to compete with overseas manufacturing in terms of price.

Of course, keeping competitive is only a concern when you actually have competitors in the first place. That’s the situation that NASA and Boeing may find themselves in should SpaceX decide to retire the Crew Dragon after 2030. While the International Space Station will (probably) be out of the equation by that point, the US space agency will still need the capability to fly humans to… somewhere, and that means there will be lucrative government contracts up for grabs.

The chances of any other American company developing and launching a human-rated spacecraft between now and the end of the decade are pretty much zero, which means Boeing will have to pick up the slack with their Starliner capsule. Or at least, try to, as Starliner hasn’t exactly had the best track record so far. Although by the 2030s SpaceX plans to have transitioned most, if not all, of its operations to Starship, one does wonder if a big enough check from Uncle Sam could change its mind.

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A laptop is shown set up on a desk next to a spectrum analyser, an SDR, and two antennas. The antennas are aimed toward assorted electronics, including headphones and a phone handset.

Reviving TEMPEST Attacks With An Injected Signal

September 20, 2026 by No comments

TEMPEST attacks are often the most effective way to break air-gapped security: rather than directly accessing a computer, the attacker records the system’s unintended radio emissions and uses them to reconstruct its internal operations. This kind of attack was much more effective in the days of noisy, high-voltage CRT displays, and has gradually become less effective as electronics migrate to quieter, less powerful components. A group of researchers, however, has found that even modern electronics can become effective TEMPEST transmitters when irradiated with an RF signal.

The RF a device emits depends on the unintentional antennas in its internal structure. These are difficult to eliminate, and it’s usually not worth the effort; they’re usually small enough that they only effectively radiate at much higher frequencies than the electronics carry. The researchers’ technique, called InjectEave, radiated these electronics with a radio frequency tuned to their internal antennas, injecting that frequency into the circuit. Nonlinear electronic components, such as amplifiers, then mix the injected frequency with the internal signal, creating RF sidebands. This mixed signal then radiates out of the device and can be picked up and demodulated to recover the device’s internal signal.

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Ski Lift Removes Mice From Chicken Coop

September 20, 2026 by 16 Comments

Getting rid of rodents like squirrels, mice, or groundhogs is a lot like digging a hole on the beach. No matter how much you remove, it’ll always fill back in. So, while [Super Valid Designs] could keep trapping and “removing” the mice in his chicken coop, more will always work their way back in. His theory is that removing them live from the chicken coop and placing them some distance away will be more effective, and with this semi-automated ski lift that traps them and carts them off, it might end up being less work too.

The build comes to us in roughly two parts. The first is the gondolas, which not only cart the mice down the hill to freedom but also double as the mousetrap themselves. They are placed in the chicken coop, and a trap door on the ceiling with bait causes the mice to fall inside. 3D printed with acrylic windows, they are a luxurious way for a mouse to travel. At the bottom, another trap door opens onto a pile of brush, releasing the mice. The second part is the lift, built hastily out of wood and other parts lying around. After much hiking up and down the hill, [Super Valid Designs] eventually got it working properly and reliably toting the mice and automatically releasing them at the bottom of the hill.

It’s a bit too early to tell if this method is more effective than more traditional methods of dealing with mice. But it was at least a fun way to deal with the problem while he also works on more effective methods of preventing the mice from getting into his buildings in the first place. There are some simpler catch-and-release mousetraps out there as well if a ski lift is out of the question for whatever reason.

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World War I Coded Message Appears Cracked, Finally

September 20, 2026 by 4 Comments

When you think of wartime cryptography, you probably think of World War II and Enigma, although there were other famous codes used during that war. But in fact, there have been codes used through wars and in peacetime for much longer. Even the Romans used codes. Of course, World War I, or The Great War, as it would have been known, had its share of codes and, as you might expect, most of these have been broken long ago. Most of them. But apparently an AI model, GPT-6 Astra, recently cracked one that was previously undeciphered.

If you aren’t up on century-old cryptography, the ADFGVX cipher appeared in 1918. It began as ADFGX, but after a few months grew an extra letter — and a larger grid. The letters were chosen because their Morse-code patterns were relatively easy to distinguish: A, D, F, G, V, and X.

The original ADFGX version used a 5×5 grid containing the alphabet, usually merging I and J. The later ADFGVX version expanded this to 6×6, making room for all the letters and the digits as well.

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Reverse Engineering A Sony Car Stereo LCD

September 20, 2026 by 2 Comments

For his own reasons, [Jose Luis Monteiro] (aka [emsyscode]) decided he needed to drive the LCD on a Sony CDX-A250 car stereo’s front panel using an Arduino. There’s probably a sweet project in the works, or perhaps he just wanted to see if it could be done. Either way, more power to [Jose], because he totally pulled it off and put the results up on GitHub for all to enjoy. There’s also a project video showing how he did the reverse-engineering, which you can see below.

The driver for this diminutive LCD is a chip obviously labeled LC75826W, and that’s what the Arduino ends up talking to. Thankfully, there was a datasheet available for that part, which gave [Jose] a great starting point for figuring out how to use it. While [Jose] is working with the LC75826W driver, he’s quite explicit in his GitHub repo that this repository is not a driver library for that chip. The code only targets the specific LCD on the CDX-A250 head unit. Still, if you’ve got a different oddball LCD that uses this driver, [Jose]’s code is a great place to start, and since it’s under an MIT license, you can fork to your heart’s content.

Kudos to Sony for not obfuscating the part or using a chip-on-board black blob — you can reverse-engineer an LCD driven by one of those, but it’s a lot more work. If you’re wondering how and why those black blobs come to be, we’ve got you covered.

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A Bandpass Filter Pulls In The Signals

September 20, 2026 by 8 Comments

It’s an unfortunate side effect of proximity to a large transmitter that the received signal can overload a receiver’s front end even when tuned to other frequencies. [Rfrht]’s had this problem with nearby FM broadcast transmissions overloading the 2 metre and 70 centimetre amateur bands. The solution?  Design and build a bandpass filter. This allows the signals you want to pass through while rejecting or attenuating out-of-band frequencies. The resulting PCB is very nice indeed.

On board, aside from the filters themselves, are a low-noise preamplifier and relays to switch between receive and transmit. Everything is controlled by logic-level signals. All components are surface-mount, and the PCB layout clearly takes special care with RF routing.

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