Disposing Of PLA And Why Composting Is Not An Option

October 16, 2026 by 2 Comments

The ‘biofriendly’ nature of poly(lactic acid) (PLA) filament often gets touted as one of its main advantages over alternatives like PETG, but even a modicum of research ought to inform a person that the biodegrading feature of PLA is only true for pure PLA without additives and at temperatures at or above its glass transition temperature (Tg). Thus the results of a year-long experiment by [I built a thing] shouldn’t be too surprising.

After burying said PLA in the garden like any self-respecting person does who tries to dispose of some evidence, the PLA suffered through a European winter and very hot, dry summer, before being dug up again recently for inspection and testing. Although not the first time that someone has tested this, it’s a good reminder considering just how much PLA filament is used each year.

In total three sample sets were used, one being the control, the other two buried in soil and compost respectively. A visual inspection showed no major difference, and a tensile strength test also showed no statistically significant change among all three sample sets. The experiment could have been concluded here, but instead calorimetry was used in a laboratory setting to see whether exposure to microbes as commonly found in soil does anything significant.

This isothermal microcalorimetry test was performed at the University of Basel, effectively to answer the question whether there’s anything in the PLA samples that can feed said microbes. As it turns out, the answer is a resounding ‘no’, with microbial activity within the presence of PLA dropping off even quicker presumably due to there being less volume available for nutrients.

When [I built a thing] contacted a large number of commercial biodegrading facilities in Switzerland, Germany and the USA, many would happily take PLA, but none of them would accepted 3D-printed PLA parts, which says a lot. The primary reason for this appears to be that even under industrial composting conditions it simply takes too long for these facilities to consider these to be economical to compost.

With PLA primarily degrading via hydrolysis, it needs to be exposed to the right conditions for this process to not take an eternity. You can of course use something like PHA instead, which doesn’t require this hydrolysis step to be biodegradable. Overall PLA is quite a crummy material, with it also suffering from embrittlement due to crystallization that will happily turn a spool of PLA into lots of sad fragments. This makes PETG into a very common and very attractive alternative to PLA.

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Running DOOM (Sort Of) On A Sonoff Smart Switch

October 16, 2026 by No comments

It’s often said in this community that DOOM can be made to run on anything, and as time goes on, that’s becoming more and more accurate. We’re at the point now that every “normal” device seems to have some version of the iconic 1993 shooter, so now there’s nothing left but to start working on the more oddball targets.

As a perfect example, [piuppi] recently wrote in to share their efforts to get DOOM — or at least something that looks like it — running on the Sonoff Basic R2 smart switch. We say something that looks like it because the game you’re seeing in the video below isn’t actually DOOM. In fact, it’s not even really a full game. It’s essentially a tech demo that’s capable of rendering graphical data pulled from the game, but only within the confines of simplistic map. Still, not bad for something designed to turn lamps on and off.

The GitHub repo includes excellent documentation should you want to rip and tear on your own Sonoff device. As you might expect the process is a bit involved, and does require you to provide your own copy of DOOM for the script to extract the necessary data from. After it’s setup, you can hit the switch from any browser on the local network and take out your frustrations on the state of modern home automation on some imps. The best part is, even after the game is installed and running on the switch, the device still actually works as a switch.

But don’t worry. Even in the unlikely event that we run out of devices that can be hacked to run DOOM, there’s still a whole world of gadgets out there that need their own port of Duke Nukem 3D.

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Another Wireless Chip Has A Hidden SDR Revealed

October 15, 2026 by 6 Comments

The news of the past couple of weeks has seen the ESP32 turned into an software-defined radio (SDR) thanks to a hidden baseband mode, an exciting development by anyone’s standards. It seems unexpected SDRs are like busses in that you wait for ages and two turn up at once, because hot on the heels of the ESP32 story is [Samson1te], revealing the SDR functionality hidden within the LR2021 LoRa chip. This one is especially interesting because as well as a 2.4 GHz radio, the chip sports a radio that works from 150 to 960 MHz.

We’re indebted to them for posting this in a comment on our receive converter post, as a complimentary project to the ESP32 one. It gives a 16-bit SDR with receive and transmit, however as with the ESP32 it’s early days and we hope great things lie ahead. There are comprehensive docs available, should you wish to enter the fray. Currently the main demo is P25 digital voice.

If you’re interested, you can follow our coverage of the ESP32 SDR.

Using Optical Waveguide Arrays To Make Sheets Sense Shapes

October 15, 2026 by 3 Comments

Determining the shape of an object which can change dynamically is a bit of a challenge, one that especially vexes those who are really into Virtual Reality. Sensing the orientation of various limbs and appendages usually requires external sensors like cameras, or limit the focus to specific details like just the hands and fingers of the player. A more comprehensive and potentially flexible approach might be possible using optical waveguides, as demonstrated by [Qifan Yu] et al. in a recent article in Advanced Intelligent Systems.

Waveguides are structures that guide electromagnetic waves, with optical waveguides such as used here targeting EM radiation in the optical band. This can even allow for the use of cheap and plentiful optical fiber, though here custom elastomeric waveguides are manufactured. These are laid out onto the sheet in a double-sided, overlapping zig-zag pattern, which allows for easy reconstruction of the shape of said sheet based on how the wave propagation through the waveguide changes.

By characterizing the behavior of the signals through the waveguide, its shape and thus that of the sheet can be reconstructed. This was then demonstrated to be accurate by wrapping the sheet around a volunteer’s arm, elbow and hand, detecting the flexing and movement of individual joints.

Although fairly bulky in the demonstrated configuration and with an unoptimized algorithm, it’s conceivably something that can be miniaturized to the point where it can be woven into regular fabric. This could make for sensor sheets that could track the configuration of everything from robots to human bodies for something like VR purposes.

45 Years Later, The Sinclair ULA Design Documents Surface

October 15, 2026 by 4 Comments

In the 8-bit home computer boom of the early 1980s, Sir Clive Sinclair’s machines were always among the cheapest on the market, often packing a surprising level of sophistication in their limited hardware. If there was one component that was key to their success it was the Ferranti ULA, or Uncommitted Logic Array, a clever way to make an ASIC from a chip containing a library of logic parts ready made. The Sinclair ULAs have been reverse engineered, but their full details have remained a mystery. Until now it seems, because here’s [Happy Little Diodes] with a treasure trove of original Ferranti design documents covering all the Sinclair parts.

The documents were picked up on eBay, and contain folders with printouts, engineering drawings, and hand written design notes. They cover the full range of Sinclair products of the era, including the ZX81 and Spectrum, the ZX printer, the Microdrive, the Spectrum Interface 1, and even the curious little flat screen TV. Oddly the IP is now held by the satellite broadcaster Sky as the holder of Amstrad’s portfolio, but fortunately Sky have recognised their historical importance and allowed their sharing with minimal changes. They’re all catalogued with download links in a Google spreadsheet, so dig in and see what you can find. Of particular interest are the ULAs that haven’t been reverse engineered yet, and the subtle differences between different versions of the same ULA as the engineers tried to fix bugs. The video is below the break.

If you’re curious about the ULA and Ferranti, we linked to a period film about it.

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Linux Kernel Drops AI Tag Requirement, Uses Meta AI For Code Reviews

October 15, 2026 by 52 Comments

Since we last covered the way that the Linux Kernel project has been dealing with the influx of code created using LLM-based coding assistants, all the way back in April, things have changed a lot, with most recently the Linux maintainers deciding to fully drop the requirement to mark LLM-assisted commits with the Assisted-by tag.

While not a fully uncontroversial decision – as also reported by Phoronix – with key maintainers already having made this decision it seems certain to proceed. This is not the only change made fairly recently, with a ‘Sashiko’ bot introduced that is supposed to handle code reviews.

In a July LKML post [Linus Torvalds] defends this decision, with a follow-up post in August by [Jakub Kicinski] it being stated that budget has been secured for using Meta’s LLMs, using said LLM-based resources for reviewing patches, as well as creating and editing commit messages. As noted by [Jakub] they’re running multiple frontier models on each patch to try and weed out confabulations.

Whether this will prove to be the right decision remains to be seen. Whereas most open source projects have firmly banished or heavily curtailed LLM-based contributions on slop, copyright as well as licensing grounds, the Linux Kernel project may be an interesting experiment in what the outcome of the exact opposite approach will be.

C64 Hardware Simulator Isn’t (Just) For Playing Around

October 15, 2026 by 10 Comments

If you want to play old Commodore games, there are C-64 emulators available for just about any platform– but most of them are so high level, they’re really meant for just that: playing games. [antirez] has a different goal with his c64-hw-sim project— it’s a lower-level emulation that simulates every chip and every connection on an ASSY 250407 motherboard, and all the chips on it, too. Ever wondered what happens when a specific chip is missing, or a random pin is shorted to ground or forced high? You can do all that in software, with no risk of harming antique hardware.

While that might be a fun bit of faffing about for a certain sort electronics sadist, the real utility is to learn about the hardware, both in the abstract and to help you troubleshoot a board you might have. It’s likely that many given failure modes reproduce the same effects– lots of things can knock out the display output, for example–but at least if you’ve reproduced a flaw in software you can try testing the hardware to see if that’s the cause of your problem. Assuming the simulation covers your hardware issue, anyway.

There’s cycle-accurate chip emulation for the processor, CIAs, SID and VIC-II via code by [Andre Weissflog], a.k.a. [flooh]. Meanwhile analog circuitry in the video, audio and power sections are not simulated so not everything fault will be replicable here. Still, it might be a neat tool– just don’t try and run any games on it, because even on high-end modern hardware it only runs at about one-third speed. That’s fast enough for diagnostics, but not so much for Maniac Mansion, never mind Elite. 

Speaking of Elite, did you know the source– both of the port and the original– is available with comments? If you want an emulator you can play, you can get it on everything from microcontrollers like Teensy to your personal computer.

Thanks to [Salvatore] for the tip!