Author: Dan Maloney

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Hackaday Links: January 5, 2025

January 5, 2025 by 4 Comments

Good news this week from the Sun’s far side as the Parker Solar Probe checked in after its speedrun through our star’s corona. Parker became the fastest human-made object ever — aside from the manhole cover, of course — as it fell into the Sun’s gravity well on Christmas Eve to pass within 6.1 million kilometers of the surface, in an attempt to study the extremely dynamic environment of the solar atmosphere. Similar to how manned spacecraft returning to Earth are blacked out from radio communications, the plasma soup Parker flew through meant everything it would do during the pass had to be autonomous, and we wouldn’t know how it went until the probe cleared the high-energy zone. The probe pinged Earth with a quick “I’m OK” message on December 26, and checked in with the Deep Space Network as scheduled on January 1, dumping telemetry data that indicated the spacecraft not only survived its brush with the corona but that every instrument performed as expected during the pass. The scientific data from the instruments won’t be downloaded until the probe is in a little better position, and then Parker will get to do the whole thing again twice more in 2025. Continue reading “Hackaday Links: January 5, 2025” →

Pi Pico Makes SSTV Reception A Snap

January 4, 2025 by 10 Comments

There’s a paradox in amateur radio: after all the time and effort spent getting a license and all the expense of getting some gear together, some new hams suddenly find that they don’t have a lot to talk about when they get in front of the mic. While that can be awkward, it’s not a deal-breaker by any means, especially when this Pi Pico SSTV decoder makes it cheap and easy to get into slow-scan television.

There’s not much to [Jon Dawson]’s SSTV decoder. Audio from a single-sideband receiver goes through a biasing network and into the Pico’s A/D input. The decoder can handle both Martin and Scottie SSTV protocols, with results displayed on a TFT LCD screen. The magic is in the software, of course, and [Jon] provides a good explanation of the algorithms he used, as well as some of the challenges he faced, such as reliably detecting which protocol is being used. He also implemented correction for “slant,” which occurs when the transmitter sample rate drifts relative to the receiver. Fixing that requires measuring the time it took to transmit each line and adjusting the timing of the decoder to match. The results are dramatic, and it clears up one of the main sources of SSTV artifacts.

We think this is a great build, and simple enough that anyone can try it. The best part is that since it’s receive-only, it doesn’t require a license, although [Jon] says he’s working on an encoder and transmitter too. We’re looking forward to that, but in the meantime, you might just be able to use this to capture some space memes.

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Dress Up Your 3D Prints With Toner-Transfer Labels

January 2, 2025 by 25 Comments

We’ve always found the various methods for adding text and graphics to 3D prints somewhat underwhelming. Embossed or debossed characters are fuzzy, at best, and multi-color printers always seem to bleed one color into the next. Still, the need for labels and logos is common enough that it’s worth exploring other methods, such as this easy toner transfer trick.

Home PCB makers will probably find the method [Squalius] describes in the video below very familiar, and with good reason. We’ve seen toner transfer used to mask PCBs before etching, and the basic process here is very similar. It starts with printing the desired graphics on regular paper using a laser printer; don’t forget to mirror the print. The printed surface is scuffed up a bit, carefully cleaned, and coated with a thick layer of liquid acrylic medium, of the kind used in paint pouring. The mirrored print is carefully laid on the acrylic, toner-side down, and more medium is brushed on the back of the paper. After the print dries, the paper is removed with a little water and some gentle friction, leaving the toner behind. A coat of polyurethane protects the artwork reasonably well.

[Squalius] has tested the method with PLA and PETG and reports good results. The text is clear and sharp, and even fine text and dithered graphics look pretty good. Durability could be better, and [Squalius] is looking for alternative products that might work better for high-wear applications. It looks like it works best on lightly textured surfaces, too, as opposed to surfaces with layer lines. We’d love to see if color laser prints work, too; [Squalius] says that’s in the works, and we’ve seen examples before that are reason for optimism.

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Lowering Your Noise Floor, The Easy Way

December 31, 2024 by 35 Comments

If there’s anything more annoying to an amateur radio operator than noise, we’re not sure what it could be. We’re talking about radio frequency noise, of course, the random broadband emissions that threaten to make it almost impossible to work the bands and pick out weak signals. This man-made interference is known as “QRM” in ham parlance, and it has become almost intolerable of late, as poorly engineered switch-mode power supplies have become more common.

But hams love a technical challenge, so when a nasty case of QRM raised its ugly head, [Kevin Loughlin (KB9RLW)] fought back. With an unacceptable noise floor of S8, he went on a search for the guilty party, and in the simplest way possible — he started flipping circuit breakers. Sure, he could have pulled out something fancier like a TinySA spectrum analyzer, but with his HF rig on and blasting white noise, it was far easier to just work through the circuits one by one to narrow the source down. His noise problem went away with the living room breaker, which led to pulling plugs one by one until he located the culprit: a Roomba vacuum’s charging station.

Yes, this is a simple trick, but one that’s worth remembering as at least a first pass when QRM problems creep up. It probably won’t help if the source is coming from a neighbor’s house, but it’s a least worth a shot before going to more involved steps. As for remediation, [Kevin] opts to just unplug the Roomba when he wants to work the bands, but if you find that something like an Ethernet cable is causing your QRM issue, you might have to try different measures.

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Ball Nut Modification Charts A Middle Course Between Building And Buying

December 29, 2024 by 7 Comments

A lot of the projects we feature here on Hackaday engender the classic “build versus buy” argument. We’ve always been puzzled by that; if anyone can appreciate the sheer joy of making something rather than buying it, it should be our readers. But there’s something to be said for buying the stuff you can buy and concentrating your effort on the bespoke aspects of the project. It’s perhaps not as exciting, but needs must, oftentimes.

Let’s not forget there’s a third way though, which [Andy] explores with this ball nut modification project. Keen-eyed readers will recall [Andy]’s recent scratch-built ball screw build, in service of some top-secret, hush-hush project related to world domination and total subjugation of humanity. His homebrew efforts in this regard were a great lesson in how to machine a complex mechanism to work in a constrained space. Still, it left folks wondering why he’d go to all the trouble when he could have just trimmed an off-the-shelf part down to size. So, he decided to give that a try.

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A Die-Level Look At The Pentium FDIV Bug

December 29, 2024 by 10 Comments

The early 1990s were an interesting time in the PC world, mainly because PCs were entering the zeitgeist for the first time. This was fueled in part by companies like Intel and AMD going head-to-head in the marketplace with massive ad campaigns to build brand recognition; remember “Intel Inside”?

In 1993, Intel was making some headway in that regard. The splashy launch of their new Pentium chip in 1993 was a huge event. Unfortunately an esoteric bug in the floating-point division module came to the public’s attention. [Ken Shirriff]’s excellent account of that kerfuffle goes into great detail about the discovery of the bug. The issue was discovered by [Dr. Thomas R. Nicely] as he searched for prime numbers. It’s a bit of an understatement to say this bug created a mess for Intel. The really interesting stuff is how the so-called FDIV bug, named after the floating-point division instruction affected, was actually executed in silicon.

We won’t presume to explain it better than [Professor Ken] does, but the gist is that floating-point division in the Pentium relied on a lookup table implemented in a programmable logic array on the chip. The bug was caused by five missing table entries, and [Ken] was able to find the corresponding PLA defects on a decapped Pentium. What’s more, his analysis suggests that Intel’s characterization of the bug as a transcription error is a bit misleading; the pattern of the missing entries in the lookup table is more consistent with a mathematical error in the program that generated the table.

The Pentium bug was a big deal at the time, and in some ways a master class on how not to handle a complex technical problem. To be fair, this was the first time something like this had happened on a global scale, so Intel didn’t really have a playbook to go by. [Ken]’s account of the bug and the dustup surrounding it is first-rate, and if you ever wanted to really understand how floating-point math works in silicon, this is one article you won’t want to miss.

The Business Card Of DOOM

December 28, 2024 by 11 Comments

This account of running DOOM on a PCB business card isn’t really about serving the “Will it DOOM?” meme of getting the classic game to run on improbable hardware. Rather, this project has more to do with getting it done right and leveraging work that’s already been done.

We’ll explain. You may recall [rsheldiii]’s previous DOOM keycap build, which was quite an accomplishment for someone who doesn’t fancy himself a hardware hacker. But he made a fair number of compromises to pull that build off, and rather than letting those mistakes propagate, he decided to build a more general platform to serve as a jumping-off point for the DOOM building community. The card is centered on the RP2040, which keeps things pretty simple. The card has a tiny LCD screen along with USB jacks for power and a keyboard, so you can actually play the game. It also has GPIO lines brought out to pads on the edge of the board, in case you want to do something other than play the game, which is shown in the brief video below.

Pretty standard stuff, right? Perhaps, but where this project stands out for us is that it stresses the importance of relying on reference circuits. We’ve all seen projects that have been derided for pulling the example circuit from the datasheet, but as [rsheldiii] points out, that seems a little wrongheaded. Component manufacturers put a lot of effort into those circuits, and they don’t do it out of the goodness of their hearts. Yes, they want to make it easier for engineers to choose their parts, but in doing so they’ve done a lot of the work for you. Capitalizing on that work wherever possible only makes sense, and in this case the results were perfect for the task at hand.

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