Misc Hacks

4139 Articles

ATTiny85 as fan controller

An ATTiny GPU Fan Controller That Sticks

August 2, 2025 by 9 Comments

When your GPU fan goes rogue with an unholy screech, you either shell out for a new one or you go full hacker mode. Well, [ashafq] did the latter. The result is a delightfully nerdy fan controller powered by an ATTiny85 and governed by a DS18B20 temperature sensor. We all know a silent workstation is golden, and there’s no fun in throwing money at an off-the-shelf solution. [ashafq]’s custom build transforms a whiny Radeon RX 550 into a cool, quiet operator. Best of all: it’s built from bits likely already in your junk drawer.

To challenge himself a bit, [ashafq] rolled his own temperature-triggered PWM logic using 1-wire protocol on an ATtiny85, all without libraries or bloated firmware. The fan’s speed only ramps up when the GPU gets toasty, just like it should. It’s efficient and clever, and that makes it a fine hack. The entire system runs off a scavenged 12V fan. He could have used a 3D printer, but decided to stick onto the card with double-sided tape. McGyver would approve.

The results don’t lie: idle temps at 40 °C, load peaking at 60 °C. Quieter than stock, smarter than stock, and way cheaper too. The double-sided tape may not last, but that leaves room for improvement. In case you want to start on it yourself, read the full write-up and feel inspired to build your own. Hackaday.io is ready for the documentation of your take on it.

Modifying fans is a tradition around here. Does it always take a processor? Nope.

Vibe Coding Goes Wrong As AI Wipes Entire Database

July 23, 2025 by 91 Comments

Imagine, you’re tapping away at your keyboard, asking an AI to whip up some fresh code for a big project you’re working on. It’s been a few days now, you’ve got some decent functionality… only, what’s this? The AI is telling you it screwed up. It ignored what you said and wiped the database, and now your project is gone. That’s precisely what happened to [Jason Lemkin]. (via PC Gamer)

[Jason] was working with Replit, a tool for building apps and sites with AI. He’d been working on a project for a few days, and felt like he’d made progress—even though he had to battle to stop the system generating synthetic data and deal with some other issues. Then, tragedy struck.

“The system worked when you last logged in, but now the database appears empty,” reported Replit. “This suggests something happened between then and now that cleared the data.” [Jason] had tried to avoid this, but Replit hadn’t listened. “I understand you’re not okay with me making database changes without permission,” said the bot. “I violated the user directive from replit.md that says “NO MORE CHANGES without explicit permission” and “always show ALL proposed changes before implementing.” Basically, the bot ran a database push command that wiped everything.

What’s worse is that Replit had no rollback features to allow Jason to recover his project produced with the AI thus far. Everything was lost. The full thread—and his recovery efforts—are well worth reading as a bleak look at the state of doing serious coding with AI.

Vibe coding may seem fun, but you’re still ultimately giving up a lot of control to a machine that can be unpredictable. Stay safe out there!

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A photo of a fully assembled PVCSub.

PVCSub: A Submarine From The Plumbing Aisle

July 18, 2025 by 11 Comments

Today in the submersibles department our hacker [Rupin Chheda] wrote in to tell us about their submarine project.

This sub is made from a few lengths of PVC piping of various diameters. There is an inflation system comprised of a solenoid and a pump, and a deflation system, also comprised of a solenoid and a pump. The inflation and deflation systems are used to flood or evacuate the ballast which controls depth. There are three pumps for propulsion and steering, one central pump for propulsion and two side pumps for directional control, allowing for steering through differential thrust. Power and control is external and provided via CAT6 cable.

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Opening A Six-Lock Safe With One Key Using Brunnian Links

July 16, 2025 by 6 Comments

Brunnian links are a type of nontrivial link – or knot – where multiple linked loops become unlinked if a single loop is cut or removed. Beyond ‘fun’ disentanglement toys and a tantalizing subject of academic papers on knot theory, it can also be used for practical applications, as demonstrated by [Anthony Francis-Jones] in a recent video. In it we get a safe that is locked with multiple padlocks, each of which can unlock and open the safe by itself.

This type of locked enclosure is quite commonly used in military and other applications where you do not want to give the same key to each person in a group, yet still want to give each person full access. After taking us through the basics of Brunnian links, including Borromean rings, we are introduced to the design behind the safe with its six padlocks.

As a demonstration piece it uses cheap luggage padlocks and Perspex (acrylic) rods and sheets to give a vibrant and transparent view of its workings. During the assembly it becomes quite apparent how it works, with each padlock controlling one direction of motion of a piece, each of which can be used to disassemble the entire locking mechanism and open the safe.

Brunnian links are also found in the braids often made by children out of elastic bands, which together with this safe can be used to get children hooked on Brunnian links and general knot theory.

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Mapping Tool Helps Identify Usable Land For Building

July 5, 2025 by 9 Comments

How would you go about identifying usable land that suits your building tastes? [Scott Sexton] was specifically looking for land that’s not too steep to build on, and realized that existing resources didn’t easily offer him this information. He thus dived into the world of GIS to try and solve this issue for himself.

[Scott] hoped that USGS maps might provide the information he needed, but found they lacked grade information, only presenting elevation and topographic data instead. From past experience reading such maps, he knew that seeing a lot of topographical lines close together tended to indicate steeper areas, but wasn’t sure on how to actually get the computer to parse this and spit out the information on steepness and grade that he wanted.

Ultimately, he set about downloading USGS elevation data in three-meter resolution. He then applied some calculus to determine the rate of change of the slope across areas of the data in order to mathematically find what he was looking for. Namely, flatter areas that would be more suitable for future construction. He then took the work even further, tweaking the output of his tools and automating until he could quickly and readily generate usability maps of areas of interest. He was even able to sanity-check his work by verifying that it correctly identified roads as obviously flat areas.

If you’ve ever tinkered with GIS work, [Scott’s] usability project may be of some interest. We’ve also seen amusing examples of what can go wrong when digital mapping data is used without sanity checks. Meanwhile, if you’ve got your own GIS hacks on the go, don’t hesitate to notify us via the tipsline!

Smart Mjolnir Makes Questionable Judgement Call On Your Worthiness

July 3, 2025 by 3 Comments

Mjolnir, also known as Thor’s hammer, is a discerning thing, at least if you believe the modern Marvel canon. [alemanjir] decided to build a semi-functional replica that makes judgement calls of its own, though they’re perhaps a little less thought-out than the storied hammer of legend.

The build consists of a 3D-printed hammer prop, inside of which is a Raspberry Pi Pico microcontroller running the show. It’s hooked up to a MPR121 touch sensor that detects when someone grips the handle of the hammer. At this point, the Pico makes a pseudorandom “worthiness check” as to whether the holder is righteous enough to wield the hammer. If they are pure of heart, it unlocks a magnet which frees the hammer from whatever metallic surface it might be stuck to. [alemanjir] also included a little additional functionality, with the hammer playing various sounds when swung thanks to a speaker and a ADXL345 accelerometer secreted inside.

One wonders whether the electromagnet inside is strong enough to hold out against an unworthy person lifting it from the ground. While it’s perhaps not as powerful or as decisive as the mythical object, it’s nonetheless a fun learning project that likely taught [alemanja] some useful basics of embedded development.

We’ve featured some terrifying takes of the Mjolnir prop before, too, like this shockingly high voltage version. Video after the break.

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Challenge: Square A Voltage

July 1, 2025 by 18 Comments

Your design task, should you decide to accept it: given an input voltage, square it. Ok, that’s too hard since squaring 8 volts would give you 64 volts, so let’s say the output should be 10% of the square, so 8 volts in would result in 6.4V. How do you do it? [Engineering Prof.] knows how and will show you what you can do in the video below.

The circuit uses two op amps and some transistors. However, the transistors are used in a way that depends on the temperature, so it is important to use a transistor array so they are matched and will all be at the same temperature.

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