A Digital Audio Recorder For TOSLink

May 5, 2026 by 7 Comments

Every now and then in our travels we come upon a project with such an obvious need that it’s almost a surprise nobody has thought of doing it before. So it is with [Elehobica]’s project, an audio recorder for S/PDIF audio streams. It’s the device you could have used, years ago!

S/PDIF, or its optical fiber cousin TOSLINK, is the digital output you’ll find on the back of Hi-Fi equipment, it’s a serial encoding of an uncompressed digital audio data stream dating from the era when CDs were new. Its relative simplicity may be what’s given it longevity — it’s easy to implement so it plugs into pretty much everything.

Perhaps back in the day it might have been a pain for an 8-bit microprocessor to handle, but in 2026 it’s no bother for a Raspberry Pi Pico. The project is a small PCB with the Pico, a few interface components, and an SD card socket, and it sends what it hears on the input to the card as WAV files. We particularly like its smart sample rate and bit depth detection, and the way it cuts up tracks based on periods of silence. If you work with SPD/IF, this is going to be a useful tool.

Perhaps it could even be fed with a laser!

LightInk, A Solar Powered ESP32 Smartwatch

May 5, 2026 by 5 Comments

There’s something about the ESP32 family of microcontrollers and timekeeping. We probably see it in clocks as often as we do anything else; we also probably see more clocks with one as the beating heart than any of the many other possible timekeeping options.

[Daniel Ansorregui]’s LightInk watch is no different in that regard — but it is very different in one important detail, because like any other smartwatch, you won’t have to worry about battery life. Outside of gloomiest Gotham, its built-in solar panel should be able to keep it charged.

That’s for a few reasons. The obvious one is the e-ink display, which only takes a sip of power during updates. That’s hardly unique to [Daniel]’s projec t– he quite explicitly calls out the Watchy project, which we featured previously, as where he got the idea of putting e-ink and an ESP32-PICO together on his wrist. What is unique is the delightful hack [Daniel] is using to minimize power usage, which is our favorite part.

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E-paper Dashboard Reimagines Smart Home’s Connection With Technology

May 5, 2026 by 9 Comments

When [Joel] and his partner got married, they had a goal to create a home with a healthy relationship to technology, which largely means avoiding smartphone use. Smartphones aren’t without their benefits, though, like being clocks and calendars, so [Joel] started looking for other options to replace these capabilities. At first he went with a “magic mirror” solution, but quickly pivoted to a wall-mounted e-paper solution he calls Timeframe which has evolved into a respectable overview for his home and life.

E-paper has a number of advantages over LCD and LED displays, one of which being that its resemblance to real paper makes it feel more organic. The first e-paper iterations of Timeframe used multiple displays in wooden frames, and [Joel] had a few different ones stationed around the house. They received their data from a custom-built Rails backend which sent pictures to the devices. This made the refresh rate possible fairly low, but a new 23.5″ display from Boox eventually enabled an acceptably high resolution and refresh rate which could support more traditional display uses. But this display required that [Joel] rewrite the entire back-end, an effort that took quite a bit of time but resulted in an impressive final product.

Like any custom-built project like this, [Joel] still has plans for improvements including those around further integration with his Home Assistant and reducing costs for future platforms. E-paper displays are popular pieces of technology for home dashboards like this, in the past we’ve seen similar, smaller builds which coincidentally have the same name.

Camera Slider: Build Instead Of Buy Goes Awry

May 4, 2026 by No comments

[TheHyperFix] had a problem. He’d spied a brilliant camera slider, but didn’t want to lay out big money to acquire it. The natural solution? Build one! Only, life is seldom so straightforward.

The plan was straightforward – take an old broken 3D printer, and repurpose its parts to make a camera slider instead. The build started with a aluminium extrusion, some V-slot wheels, and a 3D printed platform to hold the camera. Moving the platform was done via a belt drive, using the stepper motors and some software to tell the original printer controller what to do.

Unfortunately, the early experiments failed when the controller blew up under load. An Arduino was subbed in with a CNC shield, which got things back on track, and [TheHyperFix] had a somewhat functional slider with relatively jerky movement. A tough iterative design process ensued to work out problems with bearings and the Arduino’s pulse limit, among others.

As it stands, the slider is semi-functional, but it’s not quite well behaved enough to use for professional shooting. Still, for a first attempt at electronics prototyping, we think [TheHyperFix] did a pretty solid job. It might not be all there yet, but it’s well on the way, and a great deal was learned in the process.

If you’re trying to build a camera slider in a hurry, you might like to try recreating one of the builds we’ve featured before. Video after the break.

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The Math You Need To Start Understanding LLMs

May 4, 2026 by 16 Comments

Once you peel back the hype and mysticism, large language models (LLMs) are a fascinating application of statistical models, effectively what you get when you dial a basic auto-complete model up to eleven. In order to analyze a mind-boggling amount of text and produce meaningful auto-completion results quite a bit of math is involved, with a recent three-part article series by [Giles] going through the basics of inference, being the prediction step using a trained model.

The text is encoded in the LLM’s vector space as token IDs, each token being a text fragment that has some probability of following another ID, such as when cats may be found on desks, as in the above photo by [Giles]. With inference multiple of such IDs are retrieved in a vector from which in successive steps a sentence can be pieced together. These so-called logits are detailed in the first article in the series, with the second article focusing on vocabulary space and embedding, as well as the matrix operations used for inference.

Finally, the third article puts all of this together and looks at transformers, which is a crucial part of GPT (generative pretrained transformer) LLM architecture. Of note is the attention mechanism, which takes GPTs beyond merely being glorified auto-complete systems by adding pattern matching. Here we can see how the statistical model of the LLM is used to generate a rather plausible output, which is where the human has to ask themselves in how far they feel that it is correct.

Of course, there goes a lot more into making LLMs and GPTs performant, such as key-value caches that massively speed up inference.

Teardown Of A Shahed-136 Gimbaled Camera

May 4, 2026 by 28 Comments
The remains of a gimbal camera after its drone was shot down. (Credit: Le labo de Michel, YouTube)
The remains of a gimbal camera after its drone was shot down. (Credit: Le labo de Michel, YouTube)

The Iranian Shahed-136’s basic design has seen many changes and additions since Russia began using them, with some featuring interesting payloads such as cameras in a gimbal, making these drones useful for tasks like surveillance. Recently [Michel] got his hands one one such camera that was recovered from a shot-down drone in Ukraine, providing the opportunity for an in-depth look at what hardware is in these cameras.

The teardown thus covers the gimbal mechanism itself as well as the electronics and camera. First up is an Artix-7 FPGA-based board, followed by the range finder assembly. Unsurprisingly the camera feed handling is performed by an Hi3519 SoC, as this appears to be the off-the-shelf option you find all over on AliExpress and similar sites. There’s also an Artix-7 FPGA-based board here, which presumably performs some machine vision tasks or similar.

Continuing the ‘bought off AliExpress’ vibe, the power supply board (pictured above) is quite literally just that. A relay board follows the same pattern, with apparently the entire contents of the camera consisting of off-the-shelf development boards and modules that are readily found for sale online.

For the camera there is a thermal camera presumably for night operations, as most of these drone swarms are launched towards Ukraine at night. Looking at the gimbal assembly it similarly feels like it was sourced off AliExpress, featuring mostly Western components, sometimes with the typical lasered-off component markings and such.

This makes one wonder how much has changed here since nearly two years ago we saw an air data computer from a similar drone that could have been sourced off AliExpress, while the Russian missile teardowns show significantly more custom hardware, presumably because those are harder to source off AliExpress.

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Sunlight Powered, Sunlight Readable: Solar Case For Nook Simple Touch

May 4, 2026 by 4 Comments

When life gives you lemons, you make lemonade. What if life gives you a pile of old e-book readers? Well, when [spiritplumber] got box of old Nook Simple Touch devices, he decided to design solar-powered cases to help boost the old batteries. It makes perfect sense to us: sunlight readable screen, sunlight chargeable battery.

It looks like he’s got a pair of panels built into the 3D printed case. He recommends using any TP4056-based charger, and tying into the battery test points, not the 5 V supply. It won’t hurt anything if you do, apparently, but the device will think it’s plugged in an refuse to turn off the WiFi. That’s no big deal when you’ve got a continental power grid on the other end of the cable, but charging from a small panel on the back of the case doesn’t always give you enough juice to waste on unneeded radio activity. Especially indoors — these panels are apparently big enough to trickle-charge the device under artificial light, which is a nice, if doubtless slow feature.

The design is open source, and includes SketchUp design files as well as the exported .STL, so if you’ve got a hankering to edit this to fit a different e-book reader, you can. He also provides a handy-dandy guide to root this model of Nook, and if you’re on Hackaday we probably don’t need to explain why you might want to.

We’ve seen the Nook Simple Touch go some interesting places — like into the clouds as a glider computer — but solar power is a new hack for this device, at least on this site. We don’t know if [spiritplumber] has a green thumb, but he’s evidently got some environmental bones in his body: his last featured project was about improving quadcopter efficiency with a wing and a prayer.