Day: March 4, 2025

Build A Parametric Speaker Of Your Own

March 4, 2025 by 16 Comments

The loudspeaker on your home entertainment equipment is designed to project audio around the space in which it operates, if it’s not omnidirectional as such it can feel that way as the surroundings reflect the sound to you wherever you are. Making a directional speaker to project sound over a long distance is considerably more difficult than making one similar to your home speaker, and [Orange_Murker] is here with a solution. At the recent Hacker Hotel conference in the Netherlands, she presented an ultrasonic parametric speaker. It projects an extremely narrow beam of sound over a significant distance, but it’s not an audio frequency speaker at all.

Those of you familiar with radio will recognize its operation; an ultrasonic carrier is modulated with the audio to be projected, and the speaker transfers that to the air. Just like the diode detector in an old AM radio, air is a nonlinear medium, and it performs a demodulation of the ultrasound to produce an audio frequency that can be heard. She spends a while going into modulation schemes, before revealing that she drove her speaker with a 40 kHz PWM via an H bridge. The speaker itself is an array of in-phase ultrasonic transducers, and she demonstrates the result on her audience.

This project is surprisingly simple, should you wish to have a go yourself. There’s a video below the break, and she’s put all the files in a GitHub repository. Meanwhile this isn’t the first time we’ve seen a project like this.

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Smartwatches Could Flatten The Curve Of The Next Pandemic

March 4, 2025 by 72 Comments

While we’d like to think that pandemics and lockdowns are behind us, the reality is that a warming climate and the fast-paced travel of modern life are a perfect storm for nasty viruses. One thing that could help us curb the spread of the next pandemic may already be on your wrist.

Researchers at Aalto University, Stanford University, and Texas A&M have found that the illness detection features common to modern smartwatches are advanced enough to help people make the call to stay home or mask up and avoid getting others sick. They note we’re already at 88% accuracy for early detection of COVID-19 and 90% for the flu. Combining data from a number of other studies on smartwatch accuracy, epidemiology, behavior, and biology, the researchers were able to model the possible outcomes of this early detection on the spread of future diseases.

“Even just a 66-75 percent reduction in social contacts soon after detection by smartwatches — keeping in mind that that’s on a par with what you’d normally do if you had cold symptoms — can lead to a 40-65 percent decrease in disease transmission compared to someone isolating from the onset of symptoms,” says Märt Vesinurm.

We’ve got you covered if you’re looking for a smartwatch that looks a bit like a hospital wristband and we’ve also covered one that’s alive. That way, you’ll have a slimy friend when you’re avoiding other humans this time around. And when it’s time to develop a vaccine for whatever new bug is after us, how do MRNA vaccines work anyway?

Dismanteled Hallicrafters radio on workbench

Shortwave Resurrection: A Sticky Switch Fix On A Hallicrafters

March 4, 2025 by 10 Comments

Shortwave radio has a charm all its own: part history, part mystery, and a whole lot of tech nostalgia. The Hallicrafters S-53A is a prime example of mid-century engineering, but when you get your hands on one, chances are it won’t be in mint condition. Which was exactly the case for this restoration project by [Ken’s Lab], where the biggest challenge wasn’t fried capacitors or burned-out tubes, but a stubborn band selector switch that refused to budge.

What made it come to this point? The answer is: time, oxidation, and old-school metal tolerances. Instead of forcing it (and risking a very bad day), [Ken]’s repair involved careful disassembly, a strategic application of lubricant, and a bit of patience. As the switch started to free up, another pleasant surprise emerged: all the tubes were original Hallicrafters stock. A rare find, and a solid reason to get this radio working without unnecessary modifications. Because some day, owning a shortwave radio could be a good decision.

Once powered up, the receiver sprang to life, picking up shortwave stations loud and clear. Hallicrafters’ legendary durability proved itself once before, in this fix that we covered last year. It’s a reminder that sometimes, the best repairs aren’t about drastic changes, but small, well-placed fixes.

What golden oldie did you manage to fix up?

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Interposer Helps GPS Receiver Overcome Its Age

March 4, 2025 by 5 Comments

We return to [Tom Verbeure] hacking on Symmetricom GPS receivers. This time, the problem’s more complicated, but the solution remains the same – hardware hacking. If you recall, the previous frontier was active antenna voltage compatibility – now, it’s rollover. See, the GPS receiver chip has its internal rollover date set to 18th of September 2022. We’ve passed this date a while back, but the receiver’s firmware isn’t new enough to know how to handle this. What to do? Build an interposer, of course.

You can bring the module up to date by sending some extra init commands to the GPS chipset during bootup, and, firmware hacking just wasn’t the route. An RP2040 board, a custom PCB, a few semi-bespoke connectors, and a few zero-ohm resistors was all it took to make this work. From there, a MITM firmware wakes up, sends the extra commands during power-on, and passes all the other traffic right through – the system suspects nothing.

Everything is open-source, as we could expect. The problem’s been solved, and, as a bonus, this implant gives a workaround path for any future bugs we might encounter as far as GPS chipset-to-receiver comms are concerned. Now, the revived S200 serves [Tom] in his hacking journeys, and we’re reminded that interposers remain a viable way to work around firmware bugs. Also, if the firmware (or the CPU) is way too old to work with, an interposer is a great first step to removing it out of the equation completely.

Inexpensive Powder Coating

March 4, 2025 by 17 Comments

[Pete] had a friend who would powder coat metal parts for him, but when he needed 16 metal parts coated, he decided he needed to develop a way to do it himself. Some research turned up the fluid bed method and he decided to go that route. He 3D printed a holder and you can see how it all turned out in the video below.

A coffee filter holds the powder in place. The powder is “fluidized” by airflow, which, in this case, comes from an aquarium pump. The first few designs didn’t work out well. Eventually, though, he had a successful fluid bed. You preheat the part so the powder will stick and then, as usual, bake the part in an oven to cure the powder. You can expect to spend some time getting everything just right. [Pete] had to divert airflow and adjust the flow rate to get everything to work right.

With conventional powder coating, you usually charge the piece you want to coat, but that’s not necessary here. You could try a few other things as suggested in the video comments: some suggested ditching the coffee filter, while others think agitating the powder would make a difference. Let us know what you find out.

This seems neater than the powder coating guns we’ve seen. Of course, these wheels had a great shape for powder coating, but sometimes it is more challenging.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Schreibmaschine

March 4, 2025 by 6 Comments

Choc switches on a ThumbsUp! v8 keyboard with IBM Selectric typewriter keycaps, thanks to some 3D-printed adapters.
Image by [Sasha K.] via reddit
Remember that lovely Hacktric centerfold from a couple Keebins ago with the Selectric keycaps? Yeah you do. Well, so does [Sasha K.], who saw the original reddit post and got inspired. [Sasha K.] has more than one IBM Selectric lying around, which is a nice problem to have, and decided to strip one of its keycaps and get to experimenting.

The result is a nice adapter that allows them to be used with Kailh chocs — you can find the file on Thingiverse, and check out the video after the break to see how they sound on a set of clicky white chocs.

Those white chocs are attached to a ThumbsUp! v8 keyboard, a line that [Sasha K.] designed. His daily driver boards are on v9 and v10, but the caps were getting jammed up because of the spacing on those. So instead, he used v8 which has Cherry MX spacing but also supports chocs.

As you can see, there is not much to the adapter, which essentially plugs the Selectric keycap’s slot and splits the force into the electrical outlet-style pair of holes that chocs bear This feels like an easier problem to solve than making an adapter for MX-style switches. What do you think?

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It’s 2025, And Here’s A New Film Format

March 4, 2025 by 8 Comments

We love camera hacking here at Hackaday, and it’s always fascinating to see new things being done in photography. Something rather special has come our way from [Camerdactyl], who hasn’t merely made a camera, instead he’s created an entirely new analogue film format. Move over 35mm and 120, here’s the RA-4 cartridge!

RA-4 is the colour print chemistry many of you will be familiar with from your holiday snaps back in the day. Normally a negative image is projected onto it from the negative your camera took, and the positive image is developed on the paper as the reverse of that.  It can also be developed as a reversal process similar to slide film, in which the negative image is developed and bleached away leaving an unexposed positive image, which can then be exposed to light and developed to reveal a picture. This means that with carefully chosen colour correction filters it can be shot in a camera to make normal colour prints with this reversal process.

The new film format is a 3D printed cartridge system holding a long roll of RA-4 paper, which slots into a back for standard 5 by 4 inch cameras. He’s also made a modular developing machine for the process, and can get over 100 shots on a roll. A portion of the video below deals with how he wants to release it; since it has taken a huge amount of development resources he intends to release the files to the public in stages as he reaches sales milestones with his work. It’s an unusual strategy that we hope works for him, though we suspect that many camera hackers would be prepared to pay him directly for the files.

Either way, it’s a reminder that there’s still plenty of fun to be had with analogue film, and also that reversal development of RA-4 is possible. Some of us here at Hackaday have been known to hack a few cameras, we guess it’s another one to add to the “one day” list.

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