There was a time when wise older people warned you to check your tire pressure regularly. We never did, and would eventually wind up with a flat or, worse, a blowout. These days, your car will probably warn you when your tires are low. That’s because of a class of devices known as tire pressure monitoring systems (TPMS).

If you are like us, you see some piece of tech like this, and you immediately guess how it probably works. In this case, the obvious guess is sometimes, but not always, correct. There are two different styles that are common, and only one works in the most obvious way.

Obvious Guess

We’d guess that the tire would have a little pressure sensor attached to it that would then wirelessly transmit data. In fact, some do work this way, and that’s known as dTPMS where the “d” stands for direct.

Of course, such a system needs power, and that’s usually in the form of batteries, although there are some that get power wirelessly using an RFID-like system. Anything wireless has to be able to penetrate the steel and rubber in the tire, of course.

But this isn’t always how dTPMS systems worked. In days of old, they used a finicky system involving a coil and a pressure-sensitive diaphragm — more on that later.

TPMS sensor (by [Lumu] CC BY-SA 3.0Many modern systems use iTPMS (indirect). These systems typically work on the idea that a properly inflated tire will have a characteristic rolling radius. Fusing data from the wheel speed sensor, the electronic steering control, and some fancy signal processing, they can deduce if a tire’s radius is off-nominal. Not all systems work exactly the same, but the key idea is that they use non-pressure data to infer the tire’s pressure.

This is cheap and requires no batteries in the tire. However, it isn’t without its problems. It is purely a relative measurement. In practice, you have to inflate your tires, tell the system to calibrate, and then drive around for half an hour or more to let it learn how your tires react to different roads, speeds, and driving styles.

Changes in temperature, like the first cold snap of winter, are notorious for causing these sensors to read flat. If the weather changes and you suddenly have four flat tires, that’s probably what happened. The tires really do lose some pressure as temperatures drop, but because all four change together, the indirect system can’t tell which one is at fault, if any.

History

When the diaphragm senses correct pressure, the sensor forms an LC circuit. Low air pressure causes the diaphragm to open the switch, breaking the circuit.
The first passenger vehicle to offer TPMS was the 1986 Porsche 959. Two sensors made from a diaphragm and a coil are mounted between the wheel and the wheel’s hub. The sensors were on opposite sides of the tire. With sufficient pressure on the diaphragm, an electrical contact was made, changing the coil value, and a stationary coil would detect the sensor as it passed. If the pressure drops, the electrical contact opens, and the coil no longer sees the normal two pulses per rotation. The technique was similar to a grid dip meter measuring an LC resonant circuit. The diaphragm switch would change the LC circuit’s frequency, and the sensing coil could detect that.

If one or two pulses were absent despite the ABS system noting wheel rotation, the car would report low tire pressure. There were some cases of centrifugal force opening the diaphragms at high speed, causing false positives, but for the most part, the system worked. This isn’t exactly iTPMS, but it isn’t quite dTPMS either. The diaphragm does measure pressure in a binary way, but it doesn’t send pressure data in the way a normal dTPMS system does.

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Of course, as you can see in the video, the 959 was decidedly a luxury car. It would be 1991 before the US-made Corvette acquired TPMS. The Renault Laguna II in 2000 was the first high-volume car to have similar sensors.

Now They’re Everywhere

In many places, laws were put in place to require TPMS in vehicles. It was also critical for cars that used “run flat” tires. The theory is that you might not notice your run flat tires were actually flat, and while they are, as their name implies, made to run flat, they also require you to limit speed and distance when they are flat.

Old cars or other vehicles that don’t have TPMS can still add it. There are systems that can measure tire pressure and report to a smartphone app. These are, of course, a type of dTPMS.

Problems

Of course, there are always problems. An iTPMS system isn’t really reading the tire pressure, so it can easily get out of calibration. Direct systems need battery changing, which usually means removing the tire, and a good bit of work — watch the video below. That means there is a big tradeoff between sending data with enough power to go through the tire and burning through batteries too fast.

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Another issue with dTPMS is that you are broadcasting. That means you have to reject interference from other cars that may also transmit. Because of this, most sensors have a unique ID. This raises privacy concerns, too, since you are sending a uniquely identifiable code.

Of course, your car is probably also beaming Bluetooth signals and who knows what else. Not to even mention what the phone in your car is screaming to the ether. So, in practice, TPMS attacks are probably not a big problem for anyone with normal levels of paranoia.

An iTPMS sensor won’t work on a tire that isn’t moving, so monitoring your spare tire is out. Even dTPMS sensors often stop transmitting when they are not moving to save battery, and that also makes it difficult to monitor the spare tire.

The (Half Right) Obvious Answer

Sometimes, when you think of the “obvious” way something works, you are wrong. In this case, you are half right. TPMS reduces tire wear, prevents accidents that might happen during tire failure, and even saves fuel.

Thanks to this technology, you don’t have to remember to check your tire pressure before a trip. You should, however, probably check the tread.

You can roll your own TPMS. Or just listen in with an SDR. If biking is more your style, no problem.

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Espressif has unveiled its latest major chip in the form of the ESP32-E22. Officially referred to as a Radio Co-Processor (RCP), it’s intended to be used via its PCIe 2.1 or SDIO 3.0 host interface to provide wireless communications to an SoC or similar.

This wireless functionality includes full WiFi 6E functionality across all three bands, 160 MHz channel bandwidth and 2×2 MU-MIMO, making it quite a leap from the basic WiFi provided by e.g. the ESP32-S* and -C* series. There is also Bluetooth Classic and BLE 5.4 support, which is a relief for those who were missing Bluetooth Classic in all but the original ESP32 for e.g. A2DP sinks and sources.

The ESP32-E22 processing grunt is provided by two proprietary Espressif RISC-V CPU cores that can run at 500 MHz. At this point no details appear to be available about whether a low-power core is also present, nor any additional peripherals. Since the graphics on the Espressif PR article appear to be generic, machine-generated images – that switch the chip’s appearance from a BGA to an LQFP package at random – there’s little more that we can gather from there either.

Currently Espressif is making engineering samples available to interested parties after presumed vetting, which would indicate that any kind of public release will still be a while off. Whether this chip would make for an interesting stand-alone MCU or SoC along the lines of the -S3 or -P4 will remain a bit of a mystery for a bit longer.

Thanks to [Rogan] for the tip.

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There’s been a lot of virtual ink spilled about LLMs and their coding ability. Some people swear by the vibes, while others, like the FreeBSD devs have sworn them off completely. What we don’t often think about is the bigger picture: What does AI do to our civilization? That’s the thrust of a recent paper from the Boston University School of Law, “How AI Destroys Institutions”. Yes, Betteridge strikes again.

We’ve talked before about LLMs and coding productivity, but [Harzog] and [Sibly] from the school of law take a different approach. They don’t care how well Claude or Gemini can code; they care what having them around is doing to the sinews of civilization. As you can guess from the title, it’s nothing good.
Somehow the tl;dr was written decades before the paper was.
The paper a bit of a slog, but worth reading in full, even if the language is slightly laywer-y. To summarize in brief, the authors try and identify the key things that make our institutions work, and then show one by one how each of these pillars is subtly corroded by use of LLMs. The argument isn’t that your local government clerk using ChatGPT is going to immediately result in anarchy; rather it will facilitate a slow transformation of the democratic structures we in the West take for granted. There’s also a jeremiad about LLMs ruining higher education buried in there, a problem we’ve talked about before.

If you agree with the paper, you may find yourself wishing we could launch the clankers into orbit… and turn off the downlink. If not, you’ll probably let us know in the comments. Please keep the flaming limited to below gas mark 2.

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The meaning of Inception’s ending famously revolves around a top which spins forever in dreams, but in real life comes to a stop like any other top. Any other top, that is, except for [Aaed Musa]’s self-spinning top, which can continuously spin for about two hours before coming to a stop.

The one constraint was that every functional component had to be contained within the top’s shell, and [Aaed]’s first approach was to build a reaction wheel into the top. When a motor accelerates a weighted wheel, conservation of angular momentum applies an equal and opposite torque to the motor. The problem is that motors eventually reach a top speed and stop accelerating, which puts an end to the torque. This is known as saturation, and the only way to desaturate a reaction wheel is to slow it down, which counteracts the originally generated torque. [Aaed] originally planned to mount the motor in a one-way bearing, which would let it bleed off speed without producing torque against the rest of the top, but it was rather choppy in practice.

The solution occurred to [Aaed] while watching the aforementioned final scene, when it occurred to him that the wobbling of a top could actually generate rotation. A prototype proved that an off-center weight rotating at a constant speed did successfully spin the top by rotating the center of mass, and after that, it was a matter of incremental testing and improvement. A higher moment of inertia worked better, as did a lower center of gravity and a tip made from a hard, low-friction silicon nitride ball bearing. He made housings out of both 3D-printed plastic and CNC-milled aluminium, which each contained a tiny brushless motor, an electric speed controller, a microcontroller, and a small rechargeable lithium battery.

If you allow for external power, you can make the top itself the rotor of a motor, and drive it from a base. Alternatively, if you levitate your top in a vacuum, it could spin for longer than recorded history.

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Your new project really could use a block device for Linux. File systems are easy to do with FUSE, but that’s sometimes too high-level. But a block driver can be tough to write and debug, especially since bugs in the kernel’s space can be catastrophic. [Jiri Pospisil] suggests Ublk, a framework for writing block devices in user space. This works using the io_uring facility in recent kernels.

This opens the block device field up. You can use any language you want (we’ve seen FUSE used with some very strange languages). You can use libraries that would not work in the kernel. Debugging is simple, and crashing is a minor inconvenience.

Another advantage? Your driver won’t depend on the kernel code. There is a kernel driver, of course, named ublk_drv, but that’s not your code. That’s what your code talks to.

The driver maintains the block devices and relays I/O and ioctl requests to your code for servicing. There are several possible use cases for this. For example, you could dream up some exotic RAID scheme and expose it as a block device that multiplexes many devices. The example in the post, for example, exposes a block device that is made up of many discrete files on a different file system.

Do you need this? Probably not. But if you do, it is a great way to push out a block driver in a hurry. Is it high-performance? Probably not, just like FUSE isn’t as performant as a “real” file system. But for many cases, that’s not a problem.

If you want to try FUSE, why not make your favorite website part of your file system?

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DDR3 seemed plenty fast when it first showed up 19 years ago. Who could say no to 6400 Mb/s transfer speeds? Of course compared to the modern DDR5 that’s glacially slow, but given that RAM is worth its weight in gold these days– with even DDR4 spiking in price– some people, like [Gheeotine], are asking “can you game on DDR3“? The answer is a shocking yes.

[Gheeotine] builds two budget-friendly PCs for this video, using some of the newest DD3-supporting motherboards available. That’s not exactly new: we’re talking 12 to 15 years old, but hey, not old enough to drive. We certainly didn’t expect to hear about an x79 motherboard hosting an Ivy Bridge processor in 2026, but needs must when the devil dances. The only concession to modernity is the graphics cards: the x79 mobo got an RX6600XT 8GB, and the other build, using a z97 motherboard got an NVIDIA RTX 4060. The z97 motherboard allowed a slightly newer processor, as well, an i7 4790, with the new and exciting Haswell architecture you may have heard of. Both boards are maxed out on RAM, because at less than one USD/GB, why not?

[Gheeotine] puts a few new titles through their paces on these boxen, and while the results aren’t amazing, everything he tries comes out playable, which is amazing in and of itself. Well, playable unless you’re one of those people who can’t stand playing at resolutions under 4K or FPS under 100. Those of who spent their formative years with 29.7 FPS or 25 FPS in NTSC or PAL regions aren’t going to complain too loudly if frame rates dip down into the 30s playing at 1080p for some of the more demanding titles. Ironically, one of those was the five-year-old Crysis Remastered. Given the age of some of this hardware “Can it Run Crysis” is a perfectly reasonable question, and the answer is still yes.

If you want modern games, you’re much better off with a z97 chipset motherboard if you chose to go the DDR3 route, since you won’t run into issues related to the AVX2 instruction, which first appeared with the Haswell microarchitecture. Here at Hackaday our preferred solution to the rampocalypse is software optimization, Since holding your breath for that would probably be fatal, cost-optimizing PC builds is probably a good plan, even if some might balk at going all the way back to DDR3.

Of course if you’re going to use nearly-retro hardware like DDR3, you might as well go all-out on retro vibes with a nostalgic 80s-style, or even 50s-style case.

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When you’re driving a car with a stickshift, it’s pretty easy to keep track of which gear you’re in. That can be a little bit more difficult on something like a motorcycle with a sequential shifter. [decogabry] built a neat gearshift indicator to solve this issue.

An ESP32 devboard is used as the brain of the build. It’s paired with an ELM327 dongle over Bluetooth, which is able to hook into the bike’s ODB diagnostic port to pick up data like engine RPM, wheel speed, and coolant temperature. The first two factors are combined in order to calculate the current gear, since the ratio between engine RPM and wheel speed is determined directly by the gear selection. The ESP32 then commands a Philips ZM1020 Nixie tube to display the gear, driving it via a small nest of MPSA42 transistors. A separate self-contained power supply module is used to take the bike’s 12 volt supply up to the 170 volts needed to run the tube. There is also a small four-digit display used to show status information, RPM, and engine temperature.

Notably, [decogabry] made this build rather flexible, to suit any bike it might be installed upon. The gear ratios are not hard coded in software. Instead, there is a simple learning routine that runs the first time the system is powered up, which compares RPM and wheel speed during a steady-state ride and saves the ratios to flash.

We’ve featured projects before that used different techniques to achieve similar ends. It’s also interesting to speculate as to whether there’s a motorcycle vintage enough to suit a Nixie display while still having an ODB interface on board as standard. Meanwhile, if you’re cooking up your own neat automotive builds, don’t hesitate to drop us a line.

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If you were asked to pick the most annoying of the various Microsoft Windows interfaces that have appeared over the years, there’s a reasonable chance that Windows 8’s Metro start screen and interface design language would make it your choice. In 2012 the software company abandoned their tried-and-tested desktop whose roots extended back to Windows 95 in favor of the colorful blocks it had created for its line of music players and mobile phones.

Consumers weren’t impressed and it was quickly shelved in subsequent versions, but should you wish to revisit Metro you can now get the experience on Linux. [er-bharat] has created Win8DE, a shell for Wayland window managers that brings the Metro interface — or something very like it — to the open source operating system.

We have to admire his chutzpah in bringing the most Microsoft of things to Linux, and for doing so with such a universally despised interface. But once the jibes about Windows 8 have stopped, we can oddly see a point here. The trouble with Metro was that it wasn’t a bad interface for a computer at all, in fact it was a truly great one. Unfortunately the computers it was and is great for are handheld and touchscreen devices where its large and easy to click blocks are an asset. Microsoft’s mistake was to assume that also made it great for a desktop machine, where it was anything but.

We can see that this desktop environment for Linux could really come into its own where the original did, such as for tablets or other touch interfaces. Sadly we expect the Windows 8 connection to kill it before it has a chance to catch on. Perhaps someone will install it on a machine with the Linux version of .net installed, and make a better Windows 8 than Windows 8 itself.

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Space telescopes are all the rage, and rightfully so. The images they take are spectacular, and they’ve greatly increased what we know about the universe. Surely, any picture taken of, say, the Andromeda galaxy before space telescopes would be little more than a smudge compared to modern photos, right? Maybe not.

One of the most famous pictures of our galactic neighbor was taken in — no kidding — 1888. The astronomer/photographer was Isaac Roberts, a Welsh engineer with a keen interest in astrophotography. Around 1878, he began using a 180 mm refracting telescope for observations, and in 1883, he began taking photographs.

He was so pleased with the results that he ordered a reflecting telescope with a 510 mm first-surface mirror and built an observatory around it in 1885. Photography and optics back then weren’t what they are now, so adding more mirrors to the setup made it more challenging to take pictures. Roberts instead mounted the photographic plates directly at the prime focus of the mirror.

Andromeda

This image, captured with the NASA/ESA Hubble Space Telescope, is the largest and sharpest image ever taken of the Andromeda galaxy — otherwise known as M31. This is a cropped version of the full image and has 1.5 billion pixels. You would need more than 600 HD television screens to display the whole image. It is the biggest Hubble image ever released and shows over 100 million stars and thousands of star clusters embedded in a section of the galaxy’s pancake-shaped disc stretching across over 40 000 light-years. This image is too large to be easily displayed at full resolution.
Because it took hours to capture good images, he developed techniques to keep the camera moving in sync with the telescope to track objects in the night sky. On December 29th, 1888 he used his 510 mm scope to take a long exposure of Andromeda (or M31, if you prefer). His photos showed the galaxy had a spiral structure, which was news in 1888.

Of course, it’s not as good as the Hubble’s shots. In all fairness, though, the Hubble’s is hard to appreciate without the interactive zoom tool. And 100 years of technological progress separate the two.

Roberts also invented a machine that could engrave stellar positions on copper plates. The Science Museum in London has the telescope in its collection.

Your Turn

Roberts did a great job with very modest equipment. These days, at least half of astrophotography is in post-processing, which you can learn. Want time on a big telescope? Consider taking an online class. You might not match the James Webb or the Hubble, but neither did Roberts, yet we still look at his plates with admiration.

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Modern cellular networks are built to serve millions upon millions of users, all while maintaining strict encryption across all communications. But earlier cellular networks were by no means so secure, as [Nostalgia for Simplicity] demonstrates in a recent video.

The video begins with an anecdote — our narrator remembers a family member who could listen in on other’s conversations on the analog AMPS phone network. This was easily achieved simply by entering a code that would put an Ericsson handset into a test mode, in which it could be switched to tune in any desired AMPS channel. Since the communications were transmitted in a purely analog manner, with no encryption of any sort, any conversation on such a network was basically entirely open for anyone to hear. The video shows a recreation of this method, using a software-defined radio to spin up a low-power, very local AMPS network. A phone call is carried out between two handsets, with a third handset able to listen in just by using the special test mode.

If you’re particularly keen to build your own first-generation AMPS phone network, just know that it’s not really allowed due to rules around spectrum allocations. Still, it’s entirely possible as we’ve covered before. It doesn’t even take much hardware in our modern SDR era.

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You’ve likely at least heard of Marion Stokes, the woman who constantly recorded television for over 30 years. She comes up on reddit and other places every so often as a hero archivist who fought against disinformation and disappearing history. But who was Marion Stokes, and why did she undertake this project? And more importantly, what happened to all of those tapes? Let’s take a look.

Marion the Librarian

Marion was born November 25, 1929 in Germantown, Philadelphia, Pennsylvania. Noted for her left-wing beliefs as a young woman, she became quite politically active, and was even courted by the Communist Party USA to potentially become a leader. Marion was also involved in the civil rights movement.

Marion on her public-access program Input. Image via DC Video
For nearly 20 years, Marion worked as a librarian at the Free Library of Philadelphia until she was fired in the 1960s, which was likely a direct result of her political life. She married Melvin Metelits, a teacher and member of the Communist Party, and had a son named Michael with him.

Throughout this time, Marion was spied on by the FBI, to the point that she and her husband attempted to defect to Cuba. They were unsuccessful in securing Cuban visas, and separated in the mid-1960s when Michael was four.

Marion began co-producing a Sunday morning public-access talk show in Philadelphia called Input with her future husband John Stokes, Jr. The focus of the show was on social justice, and the point of the show was to get different types of people together to discuss things peaceably.

Outings Under Six Hours

Marion’s taping began in 1979 with the Iranian Hostage Crisis, which coincided with the dawn of the twenty-four-hour news cycle. Her final tape is from December 14, 2012 — she recorded coverage of the Sandy Hook massacre as she passed away.

In 35 years of taping, Marion amassed 70,000 VHS and Beta-max tapes. She mostly taped various news outlets, fearing that the information would disappear forever. Her time in the television industry taught her that networks typically considered preservation too expensive, and therefore often reused tapes.

But Marion didn’t just tape the news. She also taped various programs such as The Cosby Show, Divorce Court, Nightline, Star Trek, The Oprah Winfrey Show, and The Today Show. Some of her collection includes 24/7 coverage of news networks, all of which was recorded on up to eight VCRs: 3-5 were going all day every day, and up to 8 would be taping if something special was happening. All family outings were planned around the six-hour VHS tape, and Marion would sometimes cut dinner short to go home and change the tapes.

People can’t take knowledge from you. — Marion Stokes

You might be wondering where she kept all the tapes, or how she could afford to do this, both financially and time-wise. For one thing, her second husband John Stokes, Jr. was already well off. For another, she was an early investor in Apple stock, using capital from her in-laws. To say she bought a lot of Macs is an understatement. According to the excellent documentary Recorder, Marion own multiples of every Apple product ever produced. Marion was a huge fan of technology and viewed it as a way of unlocking people’s potential. By the end of her life, she had nine apartments filled with books, newspapers, furniture, and multiples of any item she ever became obsessed with.

In addition to the creating this vast video archive, Marion took half a dozen daily newspapers and over 100 monthly periodicals, which she collected for 50 years. This is not to mention the 40-50,000 books in her possession. In one interview, Marion’s first husband Melvin Metelits has said that in the mid-1970s, the family would go to a bookstore and drop $800 on new books. That’s nearly $5,000 in today’s money.

Why Tapes? Why Anything?

It’s easy to understand why she started with VHS tapes — it was the late 1970s, and they were still the best option. When TiVo came along, Marion was not impressed, preferring not to expose her recording habits to any possible governments. And she had every right to be afraid, with her past.

Those in power are able to write their own history. — Marion Stokes

As for the why, there were several reasons. It was a form of activism, which partially defined Marion’s life. The rest I would argue was defined by this archive she amassed.

Marion started taping when the Iranian Hostage Crisis began. Shortly thereafter, the 24/7 news cycle was born, and networks reached into small towns in order to fill space. And that’s what she was concerned with — the effect that filling space would have on the average viewer.

Marion was obsessed with the way that media reflects society back upon itself. With regard to the hostage crisis, her goal was trying to reveal a set of agendas on the part of governments. Her first husband Melvin Metelits said that Marion was extremely fearful that America would replicate Nazi Germany.

The show Nightline was born from nightly coverage of the crisis. It aired at 11:30PM, which meant it had to compete with the late-night talk show hosts. And it did just fine, rising on the wings of the evening soap opera it was creating.

To the Internet Archive

When Marion passed on December 14, 2012, news of the Sandy Hook massacre began to unfold. It was only after she took her last breath that her VCRs were switched off. Marion bequeathed the archive to her son Michael, who spent a year and half dealing with her things. He gave her books to a charity that teaches at-risk youth using secondhand materials, and he says he got rid of all the remaining Apples.
Image via The Internet Archive
But no one would take the tapes. That is, until the Internet Archive heard about them. The tapes were hauled from Philadelphia to San Francisco, packed in banker’s boxes and stacked in four shipping containers.

So that’s 70,000 tapes at let’s assume six hours per tape, which totals 420,000 hours. No wonder the Internet Archive wasn’t finished digitizing the footage as of October 2025. That, and a lack of funding for the massive amount of manpower this must require.

If you want to see what they’ve uploaded so far, it’s definitely worth a look. And as long as you’re taking my advice, go watch the excellent documentary Recorder on YouTube. Check out the trailer embedded below.

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Main and thumbnail images via All That’s Interesting

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