2026-04-18 10:00:41
Those who have worked on a hobby operating system for x86 will have interacted with its rather complex and confusing interrupt model. [Evalyn] shows us why and how to use Flexible Return and Event Delivery (FRED), a new standard by the x86 Ecosystem Advisory Group.
Of course, it would be silly to omit the fact that Linux received patches first. But that isn’t the interesting part; after all, Linux is often the first place to have support for this kind of thing. No, what’s interesting is [Evalyn]’s implementation, to our knowledge among — if not the first — non-Linux operating system to support it.
To know why we should switch to FRED, we must first understand what it replaces. The Interrupt Descriptor Table (IDT) tells the CPU what code to run when certain interrupts or faults happen. The big problem that the IDT has is inconsistency, most egregiously the fact that the stack layout depends on which interrupt happened. To solve the issues with the IDT, FRED was created.
[Evalyn] shows us the process, starting at the documentation, then finding an emulator capable of it and culminating in a demo where DOOM runs in EvalynOS with FRED enabled.
Pentium II die shot. Martijn Boer, Public domain.
2026-04-18 07:00:00
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.
2026-04-18 04:00:11
Cooking food with fire is arguably the technology that propelled humans to become the dominant species on Earth. It’s pretty straightforward to achieve, just requiring a fuel source, a supply of oxygen from the air, and a way to initiate the reaction; then it self-sustains. You wouldn’t think there’s much to improve, but what about cooking with plasma? [Jay] from the plasma channel is no stranger here, and he thinks that there may be something in this idea, certainly enough to actually build something.
Now, let’s be straight with you, this isn’t a new concept, and you can buy a plasma-based cooking appliance right now. But they are all AC-powered devices. What if you want to go camping? [Jay] attempts (and succeeds) in building a portable, rechargeable 600W plasma cooking device that can actually cook food, but it was not all plain sailing.
The existing off-the-shelf ZVS driver modules available were a bit weak and unreliable, and the required flyback coils were hard to find with the right specs, so he needed to get down to work building custom parts. First off, the coils. Custom formers were resin-printed and machine-wound with 4000 turns of fine wire, and then resin-sealed into the former. [Jay] takes care to explain that it is crucial to get all the air out of the windings, or else local flashover breakdown will occur and wreck the coil in a short time. We reckon the resulting coils look amazing in their own right!
Next, the ZVS drivers on hand had low-quality capacitors (well, not enough capacitance anyway) and cheap driver transistors, so both were upgraded. The initial plan was to have four driver/coil pairs, each driving a single pair of electrodes, with a common ground ring connecting them all. It turns out this was a terrible idea: the drivers were not synchronised, so they were pulling on each other, causing catastrophic damage to the PCBs in a very short time. The solution was more complicated wiring, to give each coil secondary output a dedicated electrode pair, so there was no direct electrical connection between neighbouring coils and no coupling between them. A clever electrode arrangement meant that a pan would sit on top of a ring of electrodes, causing plasma discharges to jump directly to the pan, thereby concentrating localised heating there. We were wondering how this new direct connection (the pan is now a common connection!) didn’t also cause backfeeding and kill the ZVS drivers again, but it didn’t seem to happen.
Anyway, [Jay] demonstrates what is possibly the world’s first rechargeable, portable plasma cooker capable of making breakfast. Which we think is very important in its own right, however, we would like a plasma-based solution to making toast next, perhaps a plasma knife that cooks the bread as you slice it?
If this plasma cooking lark rings a bell, yes, we did touch upon this way back in 2017. And whilst not strictly plasma cooking, you can make an amazing microwave plasma in this ridiculously upgraded appliance. Definitely do not try that one at home.
2026-04-18 01:30:53
We’ve all had those times when your electrical device of choice is running low on battery. Sometimes you even plan ahead and are also carrying a battery pack, but what happens when you’ve forgotten to charge the battery pack? This is the problem that [Arnov Sharma] addressed with the SolMate, a portable solar panel that keeps a battery bank topped up.
The SolMate is built around an efficient 2 W photovoltaic panel that’s not much bigger than a cellphone. This panel can supply 5 V at 400 mA on a sunny day. The solar output is more than enough to keep the internal 2000 mAh battery topped up and ready for use. Charging the Li-ion battery is handled by an IP5306 power management chip, which pulls double duty: it safely regulates charging while boosting the battery’s 3.7 V to the 5 V expected at the USB charge ports. Speaking of charge ports, the SolMate includes both a USB-A and a USB-C port, plus a switch to enable or disable the unit.
The case is all 3D printed, with some clever design choices. Offsetting the bulk of the battery and PCB storage area to one side lets the SolMate naturally cant toward the sun. Even the clip used to attach it to a backpack is printed.
Be sure to check out the other entries into our latest challenge!
2026-04-18 00:30:38
It’s the evening before publication, and a pair of Hackaday writers convene to record the week’s podcast. This week Elliot Williams is joined by Jenny List, and it’s a bumper episode!
Of course, a bit of Hackaday news makes the cut, as it’s time to make an entry in the Green Powered Challenge. Then we make the first of a couple of sojourns into AI, as we talk about the Linux kernel stance on AI code. In short: if you submit AI code you’re responsible for its bugs. Meanwhile out of this world, we look forward to a time when astronauts breathe oxygen from moon dust.
There are hacks aplenty for your enjoyment, starting with far more than you ever thought it was possible to know about sound-reactive LED strips. Then we have among others a Mac on an ESP32 forming the UI for a weather monitor, Doom on a toaster, and a fascinating look at screw threads for plastic.
In the longer reads we have our colleague [Tom Nardi] finding Chinese people’s personal data on hard drives he bought in an electronics store, and an attempt to look at what an LLM can do that might be useful. Grab your headphones, and join us!
2026-04-17 23:30:59
Well, this might just be a Hackaday first. Certainly not the circuit sculpture part, nor the wearable aspect, but the glorious combination of the two. Behold [CMoz]’s Fashionably on Task: a Smart Bracelet for Forgetfulness. The name may be long, but the intent is concise: to showcase your top five must-dos for the day.
This lovely bracelet uses a tri-color e-paper display, and it’s WiFi enabled in order to receive input from the corresponding phone app. Although the cute pink ESP32-C3 is programmed in PlatformIO, the code will work with the Arduino IDE as well.
To get down to business, just power on the bracelet. If it can’t connect to the network you’ve hard-coded, it will broadcast it’s own access point. Connect with your phone to the custom web page, and Bob’s your uncle. From here, you can enter the tasks, change the colors around, mark tasks as complete, and remove tasks or reset recurring reminders.
The nifty part is that e-paper screen, since it will of course continue to display your list once powered down. Here’s the full code. Then you can deep-dive into the graph theory of circuit sculptures.
