Hackaday Links: January 7, 2024

January 7, 2024 by Dan Maloney 27 Comments

Oh, perfect — now our cars can BSOD. At least that’s how it looks from a forum post showing a Blue Screen of Death on a Ford Mustang Mach E, warning that an over-the-air software update failed, and now the car can’t be driven. The BSOD includes a phone number to reach Ford’s Customer Relationship Center and even presents a wall of text with specific instructions to the wrecker driver for loading the bricked vehicle onto a flatbed. Forum users questioned the photo’s veracity, but there are reports of other drivers getting bricked the same way. And we’ve got to point out that even though this specific bricking happened to an EV, it could just have easily happened to an ICE vehicle too; forum members were particularly prickly about that point. It would be nice if OTA software updates on vehicles could always roll back to the previous driveable state. Still, we suppose that’s not always possible, especially if memory gets corrupted during the update. Maybe the best defense against a bricked vehicle would be to keep a beater around that doesn’t need updates to keep running.

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Using Sound Waves As A Fire Extinguisher

January 7, 2024 by Maya Posch 15 Comments

In order for a fire to sustain itself, it needs three things: fuel, heat, and oxygen, with the disruption of just one of those causing the fire to extinguish. Water, sand, and carbon dioxide-based fire extinguishers are commonly used, but you’re probably familiar with blowing out a candle using your breath. Counter-intuitively, we also blow on a fire (or use bellows) to make it burn better, so what is happening here? Starting with a novelty app for smartphones that can be used to blow out small flames like candles, [The Action Lab] digs into the topic in a recent video.

Using an air vortex cannon strapped to a bass reflex port to wiggle a flame to death. (Credit: The Action Lab)

Using a fairly beefy speaker to blast a 70 Hz tone at a big alcohol flame was not enough to extinguish it, but using the bass reflex port on the back was more effective, yet still not nearly enough. Using an air vortex cannon to focus the sound waves from the bass reflex port, it ‘wiggles’ the flame out in a matter of seconds, as illustrated with a thermal camera. Compared to the much stronger airflow from the box fan that was also used in one attempt, the difference with the sound waves is that they oscillate, constantly fluctuating the air pressure.

This churns the air and thus the flame around, diffusing the suspended fuel, cooling the air, and alternatingly pushing oxygenated air and carbon dioxide-heavy combustion fumes into the flame. This differs from the constant flow from the box fan, which only pushes oxygen-rich air into the flame, thus keeping it intact and burning brightly. Perhaps the main question that remains here is just how practical this approach is for extinguishing flames. Some commentators suggested using this approach in low- and zero-gravity situations, as found in space stations, where regular fire extinguishers based around smothering a flame aren’t as practical.

(Thanks to [Hyperific] for the tip)

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Recreating The Jupiter ACE

January 7, 2024 by Al Williams 25 Comments

What looks like a Sinclair ZX81 but runs Forth? If you said a Jupiter ACE, you get a gold star. These are rare because ordinary people in 1982 didn’t want Forth, so only about 5,000 of the devices were sold. [Cees Meijer] assumes they are unaffordable, so he built a replica and shows you how you can, too. [Scott Baker] built one recently; you can see his video below.

The resemblance to the Sinclair computer wasn’t just a coincidence. Richard Altwasser and Steven Vickers were behind the computer, and both had worked for Sinclair previously. In addition to being famous for using Forth, the machine initially had a badly manufactured case and an unreliable keyboard. A later version tried to correct these issues, but there were fewer than 1,000 made. [Cees’] replica used a design from [Grant Searle] with some modifications.

We liked the realistic look of the 3D printed keyboard. The keyboard uses white plastic with raised letters. A quick black spray paint followed by sanding gives the appearance of black keys with white printed text.

Overall, this is a good-looking build of a computer you probably won’t see in person. We wish Forth had caught on in the early PC world, but it didn’t. [Grant] was prolific with replica computers, and [Cees] isn’t the only one who used that work as a starting point for their own projects. If you want real old-school Forth, you have to go back a few more years.

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Remote-Control Kinetic Sand Table Uses A Single Arduino

January 7, 2024 by Kristina Panos 11 Comments

There’s nothing fun about a Sisyphean task unless you’re watching one being carried out by someone or something else. In that case, it can be mesmerizing like this Arduino-driven kinetic sand table.

What you can’t see. Image via [thang010146] on YouTube

Like many of these builds, it all started with an ordinary coffee table from the hacker’s favorite furnitüre store. [NewsonsElectronics] opened it up and added a 3mm-thick board to hold the sand and another to hold the rails and magnets.

After designing some pieces to connect the rails and pulleys together, [NewsonsElectronics] let the laser cutter loose on some more 3mm stock. A pair of stepper motors connected to a CNC shield do all of the work, driving around a stack of magnets that causes the ball bearing to trudge beautifully through the sand.

Be sure to check out the videos after the break. The first is a nice demonstration, and the second is the actual build video. In the third video, [NewsonsElectronics] explains how they could write the world’s smallest GRBL code to swing this with a single Arduino. Hint: it involves removing unnecessary data from the g-code generated by Sandify.

Don’t have a laser cutter? Here’s a sand table built from 3D printer parts.

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802.11ah Wi-Fi HaLOW: The 1 Kilometer WiFi Standard

January 7, 2024 by Maya Posch 31 Comments

The 802.11ah WiFi (HaLow) standard is fairly new, having only been introduced in 2017. It’s supposed to fall somewhere between standard WiFi used in domiciles and offices and the longer range but low-bitrate LoRaWAN, ZigBee, and others, with bandwidth measured in megabits per second. In a recent video, [Ben Jeffery] looks at the 802.11ah chipsets available today and some products integrating these.

The primary vendors selling these chipsets are TaiXin Semiconductor (TXW8301), Morse Micro (MM6108), and Newracom (NRC7394), with a range of manufacturers selling modules integrating these. Among the products using these, [Ben] found an Ethernet range extender kit (pictured) that takes 12V input as power, along with Ethernet. Running some distance tests in a quarry showed that 300 meters was no problem getting a strong signal, though adding some trees between the two transceivers did attenuate the signal somewhat.

Another interesting product [Ben] tested is what is essentially an 802.11ah-based WiFi extender, using an 802.11ah link between the server node – with an Ethernet socket – and a client that features a standard 2.4 GHz 802.11n that most WiFi-enabled devices can connect to. Using this, he was able to provide a solid ~10 Mbps link to a cabin near the main house (~10 meters) through two outside walls. What makes 802.11ah so interesting is that it is directly compatible with standard Ethernet and WiFi protocols and uses the 900 MHz spectrum, for which a wide range of alternative antennae exist that can conceivably extend the range even more.

(Thanks to [Keith Olson] for the tip)

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A Journey Through Font Rendering

January 7, 2024 by Matthew Carlson 8 Comments

In the wide world of programming, there are a few dark corners that many prefer to avoid and instead leverage the well-vetted libraries that are already there. [Phillip Tennen] is not one of those people, and when the urge came to improve font rendering for his hobby OS, axle, he got to work writing a TrueType font renderer.

For almost a decade, the OS used a map table encoding all characters as 8×8 bitmaps. While scaling works fine, nonfractional scaling values are hard to read, and fractional scaling values are jagged and blocky. TrueType and font rendering, in general, are often considered dark magic. Font files (.ttf) are structured similarly to Mach-O (the binary format for macOS), with sections containing tagged tables. The font has the concept of glyphs and characters. Glyphs show up on the screen, and characters are the UTF/Unicode values that get translated into glyphs by the font. Three critical tables are glyf (the set of points forming the shape for each glyph), hmtx (how to space the characters), and cmap (how to turn Unicode code points into glyphs).

Seeing the curtain pulled back from the format itself makes it seem easy. In reality, there are all sorts of gotchas along the way. There are multiple types of glyphs, such as polygons, blanks, or compound glyphs. Sometimes, control points in the glyphs need to be inferred. Curves need to be interpolated. Enclosed parts of the polygon need to be filled in. And this doesn’t even get to the hinting system.

Inside many fonts are tiny programs that run on the TrueType VM. When a font is rendered at low enough resolutions, the default control points will lose their curves and become blobs. E’s become C, and D’s become O’s. So, the hinting system allows the font to nudge the control points to better fit on the grid. Of course, [Phillip] goes into even more quirks and details in a wonderful write-up about his learnings. Ultimately, axle has a much better-looking renderer, we get a great afternoon read, and fonts seem a little less like forbidden magic.

Maybe someday [Phillip] will implement other font rendering techniques, such as SDF-based text renderers. But for now, it’s quite the upgrade. The source code is available on GitHub.

An Adjustable High-Voltage Power Supply Built With Safety In Mind

January 6, 2024 by Dan Maloney 11 Comments

It’s not entirely clear why [Advanced Tinkering] needs a 50,000-volt power supply, but given the amount of work he put into this one, we’re going to guess it will be something interesting.

The stated specs for this power supply are pretty simple: a power supply that can be adjusted between 20kV and 50kV. The unstated spec is just as important: don’t kill yourself or anyone else in the process. To that end, [Advanced] put much effort into making things as safe as possible. The basic architecture of the supply is pretty straightforward, with a ZVS driver and an AC flyback transformer. Powered by a 24-volt DC supply and an adjustable DC-DC converter, that setup alone yields something around 20kV — not too shabby, but still far short of the spec. The final push to the final voltage is thanks to a three-stage Cockcroft-Walton multiplier made with satisfyingly chunky capacitors and diodes. To ensure everything stays safe in the high-voltage stage, he took the precaution of potting everything in epoxy. Good thing, too; tests before potting showed arcing in the CW multiplier despite large isolation slots in the PCB.

Aside from the potting, some really interesting details went into this build, especially on the high-voltage side. The 3D-printed and epoxy-filled HV connector is pretty cool, as is the special wire needed to keep arcs at bay. The whole build is nicely detailed, too, with care taken to bond each panel of the rack-mount case to a common ground point.

It’s a nice build, and we can’t wait to see what [Advanced Tinkering] does with it. In the meantime, if you want to get up to speed on handling high voltage safely, check out our HV primer.

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