Perovskite Solar Cell Crystals See The Invisible

September 16, 2025 by Heidi Ulrich 14 Comments

A new kind of ‘camera’ is poking at the invisible world of the human body – and it’s made from the same weird crystals that once shook up solar energy. Researchers at Northwestern University and Soochow University have built the first perovskite-based gamma-ray detector that actually works for nuclear medicine imaging, like SPECT scans. This hack is unusual because it takes a once-experimental lab material and shows it can replace multimillion-dollar detectors in real-world hospitals.

Current medical scanners rely on CZT or NaI detectors. CZT is pricey and cracks like ice on a frozen lake. NaI is cheaper, but fuzzy – like photographing a cat through steamed-up glass. Perovskites, however, are easier to grow, cheaper to process, and now proven to detect single photons with record-breaking precision. The team pixelated their crystal like a smartphone camera sensor and pulled crisp 3D images out of faint radiation traces. The payoff: sharper scans, lower radiation doses, and tech that could spread beyond rich clinics.

Perovskite was once typecast as a ‘solar cell wonder,’ but now it’s mutating into a disruptive medical eye. A hack in the truest sense: re-purposing physics for life-saving clarity.

Neural network shown on original mac screen, handwritten 2 on left and predictions on right

Original Mac Limitations Can’t Stop You From Running AI Models

September 15, 2025 by Ian Bos 14 Comments

Modern retrocomputing tricks often push old hardware and systems further than any of the back-in-the-day developers could have ever dreamed. How about a neural network on an original Mac? [KenDesigns] does just this with a classic handwritten digit identification network running with an entire custom SDK!

Getting such a piece of hardware running what is effectively multiple decades of machine learning is as hard as most could imagine. (The MNIST dataset used wasn’t even put together until the 90s.) Due to floating-point limitations on the original Mac, there are a variety of issues with attempting to run machine learning models. One of the several hoops to jump through required quantization of the model. This also allows the model to be squeezed into the limited RAM of the Mac.

Impressively, one of the most important features of [KenDesigns] setup is the custom SDK, allowing for the lack of macOS. This allows for incredibly nitty-gritty adjustments, but also requires an entire custom installation. Not all for nothing, though, as after some training manipulation, the model runs with some clear proficiency.

If you want to see it go, check out the video embedded below. Or if you just want to run it on your ancient Mac, you’ll find a disk image here. Emulators have even been tested to work for those without the original hardware. Newer hardware traditionally proves to be easier and more compact to use than these older toys; however, it doesn’t make it any less impressive to run a neural network on a calculator!

Continue reading “Original Mac Limitations Can’t Stop You From Running AI Models” →

E-Waste And Waste Oil Combine To Make Silver

September 14, 2025 by Tyler August 13 Comments

As the saying goes, “if it can’t be grown, it has to be mined”– but what about all the metals that have already been wrested from the bosom of the Earth? Once used, they can be recycled– or as this paper charmingly puts it, become ore for “urban mining” techniques. The technique under discussion in the Chemical Engineering Journal is one that extracts metallic silver from e-waste using fatty acids and hydrogen peroxide.

This “graphical abstract” gives the rough idea.

Right now, recycling makes up about 17% of the global silver supply. As rich sources of ore dry up, and the world moves to more sustainable footing, that number can only go up. Recycling e-waste already happens, of course, but in messy, dangerous processes that are generally banned in the developed world. (Like open burning, of plastic, gross.)

This paper describes a “green” process that even the most fervant granola-munching NIMBY wouldn’t mind have in their neighborhood: hot fatty acids (AKA oil) are used as an organic solvent to dissolve metals from PCB and wire. The paper mentions sourcing the solvent from waste sunflower, safflower or canola oil. As you might imagine, most metals, silver included, are not terribly soluble in sunflower oil, but a little refining and the addition of 30% hydrogen peroxide changes that equation.

More than just Ag is picked up in this process, but the oils do select for silver over other metals. The paper presents a way to then selectively precipitate out the silver as silver oleate using ethanol and flourescent light. The oleate compound can then be easily washed and burnt to produce pure silver.

The authors of the paper take the time to demonstrate the process on a silver-plated keyboard connector, so there is proof of concept on real e-waste. Selecting for silver means leaving behind gold, however, so we’re not sure how the economics of this method will stack up.

Of course, when Hackaday talks about recycling e-waste, it’s usually more on the “reuse” part of “reduce, reuse, recycle”. After all, one man’s e-waste is another man’s parts bin–or priceless historical artifact.

Thanks to [Brian] for the tip.Your tips can be easily recycled into Hackaday posts through an environmentally-friendly process via our tipsline.

A worker inspects JUNO's acrylic sphere under the watching eye of PMTs

Worlds Largest Neutrino Detector Is Collecting Data In China

September 1, 2025 by Tyler August 16 Comments

To say that neutrinos aren’t the easiest particles to study would be a bit of an understatement. Outside of dark matter, there’s not much in particle physics that is as slippery as the elusive “ghost particles” that are endlessly streaming through you and everything you own. That’s why its exciting news that JUNO is now taking data as the world’s largest detector.

First, in case you’re not a physics geek, let’s go back to basics. Neutrinos are neutral particles (the name was coined by Fermi as “little neutral one”) with very, very little mass and a propensity for slipping in between the more-common particles that make up everyday matter. The fact that neutrinos have mass is kind of weird, in that it’s not part of the Standard Model of Particle Physics. Since the Standard Model gets just about everything else right (except for dark matter) down to quite a few decimal points, well… that’s a very interesting kind of weird, hence the worldwide race to unravel the mysteries of the so-called “ghost particle”. We have an explainer article here for anyone who wants more background.

Continue reading “Worlds Largest Neutrino Detector Is Collecting Data In China” →

Google Will Require Developer Verification Even For Sideloading

August 26, 2025 by Maya Posch 118 Comments

Do you like writing software for Android, perhaps even sideload the occasional APK onto your Android device? In that case some big changes are heading your way, with Google announcing that they will soon require developer verification for all applications installed on certified Android devices – meaning basically every mainstream device. Those of us who have distributed Android apps via the Google app store will have noticed this change already, with developer verification in the form of sending in a scan of your government ID now mandatory, along with providing your contact information.

What this latest change thus effectively seems to imply is that workarounds like sideloading or using alternative app stores, like F-Droid, will no longer suffice to escape these verification demands. According to the Google blog post, these changes will be trialed starting in October of 2025, with developer verification becoming ‘available’ to all developers in March of 2026, followed by Google-blessed Android devices in Brazil, Indonesia, Thailand and Singapore becoming the first to require this verification starting in September of 2026.

Google expects that this system will be rolled out globally starting in 2027, meaning that every Google-blessed Android device will maintain a whitelist of ‘verified developers’, not unlike the locked-down Apple mobile ecosystem. Although Google’s claim is that this is for ‘security’, it does not prevent the regular practice of scammers buying up existing – verified – developer accounts, nor does it harden Android against unscrupulous apps. More likely is that this will wipe out Android as an actual alternative to Apple’s mobile OS offerings, especially for the hobbyist and open source developer.

CERN’s Large Hadron Collider Runs On A Bendix G-15 In 2025

August 25, 2025 by Adam Fabio 19 Comments

The Bendix G-15 refurbished by [David at Usagi Electric] is well known as the oldest fully operational digital computer in North America. The question [David] gets most is “what can you do with it?”. Well, as a general-purpose computer, it can do just about anything. He set out to prove it. Can a 1950s-era vacuum tube computer handle modern physics problems? This video was several years in the making, was a journey from [David’s] home base in Texas all the way to CERN’s Large Hadron Collider (LHC) in Switzerland.

The G-15 can run several “high-level” programming languages, including Algol. The most popular, though, was Intercom. Intercom is an interactive programming language – you can type your program in right at the typewriter. It’s much closer to working with a basic interpreter than, say, a batch-processed IBM 1401 with punched cards. We’re still talking about the 1950s, though, so the language mechanics are quite a bit different from what we’re used to today.

To start with, [Usagi’s] the G-15 is a numeric machine. It can’t even handle the full alphabet. What’s more, all numbers on the G-15 are stored as floating-point values. Commands are sent via operation codes. For example, ADD is operation 43. You have to wrangle an index register and an address as well. Intercom feels a bit like a cross between assembler and tokenized BASIC. Continue reading “CERN’s Large Hadron Collider Runs On A Bendix G-15 In 2025” →

How To Stop Zeus From Toasting Your Pi

August 22, 2025 by Heidi Ulrich 18 Comments

If you’ve ever lost gear to lightning or power spikes, you know what a pain they are. Out in rural Arkansas, where [vinthewrench] lives, the grid is more chaos than comfort – especially when storms hit. So, he dug into the problem after watching a cheap AC-DC module quite literally melt down. The full story, as always, begins with the power company’s helpful reclosers: lightning-induced surges, and grid switching transients. The result though: toasted boards, shorted transformers, and one very dead Raspberry Pi. [vinthewrench] wrote it all up – with decent warnings ahead. Take heed and don’t venture into things that could put your life in danger.

Back to the story. Standard surge suppressors? Forget it. Metal-oxide varistor (MOV)-based strips are fine for office laptops, but rural storms laugh at their 600 J limits. While effective and commonly used, MOVs are “self-sacrificing” and degrade over time with each surge event.

[vinthewrench] wanted something sturdier. Enter ZeusFilter 1.0 – a line-voltage filter stitched together from real parts: a slow-blow fuse, inrush-limiting thermistor, three-electrode gas discharge tube for lightning-class hits, beefy MOVs for mid-sized spikes, common-mode choke to kill EMI chatter, and safety caps to bleed off what’s left. Grounding done right, of course. The whole thing lives on a single-layer PCB, destined to sit upstream of a hardened PSU.

As one of his readers pointed out, though, spikes don’t always stop at the input. Sudden cut-offs on the primary can still throw nasty pulses into the secondary, especially with bargain-bin transformers and ‘mystery’ regulators. The reader reminded that counterfeit 7805s are infamous for failing short, dumping raw input into a supposedly safe 5 V rail. [vinthewrench] acknowledged this too, recalling how collapsing fields don’t just vanish politely – Lenz makes sure they kick back hard. And yes, when cheap silicon fails, it fails ugly: straight smoke-release mode.

In conclusion, we’re not particularly asking you to try this at home if you lack the proper knowledge. But if you have a high-voltage addiction, this home research is a good start to expand your knowledge of what is, in theory, possible.