A Good DIY Solder Stencil Begins With A Cleanly-Sliced Soda Can

Solder stencils are a fantastic way to accurately apply solder paste to a PCB. Professionally-made stencils are cut from steel, but for the home hacker, soda cans continue to be the alternative of choice. The only trick is how to actually get those little holes made, and [Saheen Palayi] shows off both his method of laser-engraving the holes, as well as a tool for cutting the can in the first place.

A good result starts with cutting a can cleanly, thanks to a 3D-printed tool.

To turn a soda can into a flat-ish aluminum sheet means cutting off the ends and slicing it open. Ideally, one achieves this without kinking or bending the thin metal. In practice, this is quite difficult. [Saheen]’s solution is something a little like a pipe cutter — a 3D printed tool that gradually presses a blade section from a utility knife into the empty can as it turns until it cuts through. Once the top and bottom are off, it’s easy enough to snip down the side to get a curved sheet.

The hole pattern comes from one’s PCB design software of choice, and the actual cutting is done by a fiber laser. The wavelength of fiber lasers makes them good at marking and cutting metal, and [Saheen]’s laser takes almost no time at all to cut the stencil into the thin metal.

Fiber lasers used to be the sort of tool that only industrial shops had, but they’re a prosumer-level tool that can be bought online nowadays. [Saheen] uses an xTool F1 Ultra to cut his solder stencil, and we’ve previously seen that same laser used to create a PCB by blasting away unwanted copper until only the traces remain.

We’ve seen aluminum cans etched and also machined to create stencils, and the laser is certainly the fastest. Watch it in action in the video below.

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The prototype Vectron65 on breadboard with the VGA Plus v2 and VGA Text Mode cards

2026 Retrocomputer Challenge: Vectron65 Plus Puts The Emphasis On Plus

[Nick Bild] evidently has a soft spot for the 6502, given that his Vectron65 Plus home computer project uses at least one of them, depending on the add-ons. You see, he hasn’t just made a homebrew computer, he’s also produced multiple expansions. One of which, the VGA Plus Text Mode, has its own 6502 co-processor. He’s also produced two versions of a VGA graphics card capable of 640×480 output. We’re still not 100% sure how many entries we are going to count [Nick]’s work as for the contest, since the graphics cards can be used with just about anything, not just the Vectron65, but we do know they’re strong contenders every one.

The video doesn’t really show the graphics, so here’s an example.

We covered the start of the Vectron65 project back in 2019, and it’s only gotten more practical as it has moved off breadboard onto PCB, and into a new version as the 65 Plus with more RAM and GPIO ports. Considering that the original let you game in VR using an add-on we covered, we might have to drop the “nearly” from “nearly practical” when talking about the Plus. Especially when you consider the graphics — we covered first version of 7400-series based VGA graphics card, while the newer V2 differs mostly in doubling the RAM and producing a more stable output. The V2 VGA card can work in tandem with the Text Mode card to write 40-column text to the screen without using up all the 6502 CPU’s cycles, offloading them to the second 6502 on the card with the help of a character ROM. Hey, if Commodore could put a second 6502 in a disk drive, why not? You can check out the whole suite in action in the demo video below. We admit to being particularly tickled by the Hackaday Comment Generator he’s running in BASIC.

If you’re worried about competing with [Nick], don’t worry — the 2026 Retrocomputing contest has multiple categories. You still have a few weeks to do something retro-modern, restomod an old machine, or just do some old-school programming.

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The ESP32, An SDR In Itself

Perhaps the most famous of all the software-defined radio (SDR) receivers is the RTL-SDR, a digital TV receiver on which an undocumented feature was found. Perhaps other radio-enabled chips also have the same undocumented feature? It seems in the case of some members of the ESP32 family, they do. It’s a discovery made independently in two places, by Espargos, and a Reddit user by the name of h0m3us3r.

What’s happening is that the undocumented mode taps the I/Q stream off before the WiFi modem, and this can be read and processed by SDR software on an external computer. The undocumented mode can be found on ESP32 chips with the earlier Tensilica hardware onwards, so the low power Bluetooth only chips or the non-radio-equipped P4 won’t work. Sadly it’s also only possible with the receive side, with both 2.4 and 5 GHz bands being supported depending on the microcontroller in question.

This isn’t quite the general purpose SDR we got with the RTL-SDR, but there are still plenty of uses to which it can be put. We’re curious as to whether someone can implement the software side of an SDR on the same chip, but we are guessing that might be beyond their capabilities. Either way, we’re looking forward to what the community does with this new-found knowledge.

Fixing A Power Grid That Loses Over Half Its Power To Inefficiency And Theft

[Mini Shaji Thomas] has a deeply interesting article on IEEE Spectrum detailing how the power distribution system for a city of over twenty million people went from failing to first-class. In the early 2000s, over half of Delhi’s generated power was lost to inefficiencies of all kinds, and theft. Losses were technical as well as administrative, and the rampant theft was perpetuated by “both the powerful and the powerless”. Spoiler alert: it’s a big job.

That level of loss is staggering, and caused by many issues rather than just one or two. Many of the problems tended to compound one another. For example, an effective power grid relies on balancing active and reactive power, but if that is not well managed then inefficiencies cause losses and outages that tend to lead to even more losses and outages as the system is never able to catch up to demand. On the scale of tens of millions of inhabitants, such losses are far from trivial.

There wasn’t a silver bullet solution. Modernizing and stabilizing the power distribution required technical resources, modernized equipment, political will, expert planning, a willingness to follow through, and authority.

The starting point was grim: a failing network that was constantly overloaded, poor or nonexistent controls and safeguards, inaccurate records and inefficient administration, no real means of sensing faults or inefficiencies or theft, weak to nonexistent enforcement, and an untrained workforce. Still, it could be done, and it was. While there’s still improvement to be made, revamping the system was ultimately successful.

Individually, some of the solutions were quite simple. For example, replacing bare overhead distribution wires with a system of insulated cables containing multiple conductors was not just safer and more resilient, it made it much harder for people to tap into the lines. Other initiatives like making it easier and more convenient to pay accurate bills helped, too. Turns out it’s easier to have legit customers when the product and service is reliable.

Give it a read if you have a few minutes, because besides providing a peek into the technical end of how effective power grids work, it’s a good analysis of what can be accomplished with some co-operation and a willingness to change.

Own The OSD Chip In Your Cheap Composite Monitor

[Ogrinz Labs] has built a Robbie the Robot suit, which is super-cool, but has a huge flaw. When inside the suit, he’s too tall to do what the original Robbie actor did, which was to look through the “mouth” grille. He solved this with an inexpensive automotive reversing camera, but then realised its monitor had a built-in on-screen-display chip. After a lot of work, he’s published a GitHub repository that allows access to this thing for custom on-screen graphics.

The chip in question is an AMT630A, which contains video switching hardware, a graphics system for the on-screen-display, and an 8052 microcontroller core. He didn’t manage to get into the 8052’s brain, but the video below details the long path towards controlling it through an I2C port with an ESP32. The software is available as an Arduino library. His intention is to use it as a display for navigational sensor data to aid in maneuvering Robbie.

Given the status of Robbie as a sci-fi movie icon, it should come as no surprise that we’ve featured this suit before,

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That’s No Moon… That’s An Exoplanet!

It wasn’t that long ago that a science teacher would have told students that there was no evidence of planets around other star systems. Even more recently, they might have said that while we’ve seen evidence of extra-solar planets, we would never be able to see them directly. But that’s all changed. [Jason Wang] has several videos that use images taken over years to visualize the orbit of several large exoplanets.

Of course, some extrapolation is involved. According to [Jason]:

We unfortunately do not have the luxury of watching these planets every night and record them. However, these planets move slowly, with orbital periods at least decades long, and predictably following Kepler’s laws. We can use a technique called motion interpolation to reconstruct what the image should look like using images taken before and after the date we are interested in. Motion interpolation is a technique commonly found in video editing and in modern TVs.

You have to be a patient photographer, apparently. One video has 30 images taken over 17 years, for example. Another has 10 images from the Keck Observatory taken over 12 years.

The work has fed scientific papers like this one or this one. While it might be more fun to see these star systems from the bridge of your favorite starship, this is probably as close as you are going to get.

We find both the prospect of exoplanets and the technology used to find them exciting

Is This The Smallest Internet Radio?

Internet radios have been a thing in some form for the last quarter century, and the advent of cheap networked microcontrollers has made them easier than ever to build. But just how small can one be made? [Milen] has made one that’s about as small as we’ve seen, and put it up on Instructables.

The hardware recipe is straightforward enough; take a microcontroller, connect it to the internet, and have your internet radio software squirt its output to a DAC. In this case the microcontroller is an ESP32-C£ on a very small dev board, and clipped to that is a custom PCB with a PCM5102A I2S DAC and an amplifier. The whole thing is tiny, small enough in fact that the two connectors are significant in size compared to it.

Whether or not it’s a practical device for listening remains to be seen, but it’s certainly tiny. But the question is, could it be made smaller? Perhaps eschewing the connectors would be an easy win, and in return for a loss in quality the ESP has a built-in DAC that’s not intended for audio but can be used. If you have any bright ideas, we’d be interested to hear them.

We’ve seen plenty of internet radios over the years, and for some reason this cassette-shaped one appeals to us.