An audio spectrogram is shown in the middle of the image, with intensity plots shown both above and below the spectrogram. A vertical yellow line runs through all three graphs.

Determining Location By Listening For Airplanes

November 9, 2026 by No comments

Beyond what people deliberately disclose, there’s a surprising amount of information hidden in everyday messages, especially photos and videos. Even when people try to hide the location or time at which something was recorded, small details make these surprisingly difficult to obscure. One of the more well-known techniques correlates mains-frequency hum with power grid frequency variations. In a similar vein, [colsto] recently developed a powerful technique for precisely geolocating videos using the Doppler curves generated by passing aircraft.

Since aircraft are often audible for miles in all directions, they’re particularly likely to be inadvertently picked up in a video. The aircraft may not be discernible to the human ear, but the sound it makes can still show up in a spectrogram. To turn this data into a location, the pattern of Doppler curves needs to be correlated to an aircraft’s flight path. This is easy enough using public ADS-B records, which provide a timestamped history of each aircraft’s location, altitude, speed, and heading.

Having more than one Doppler curve in the recording simplifies the location process significantly: it’s possible to simply search for points at which Doppler curves would have been heard with the correct interval between them. It’s also important to exclude locations at which more Doppler curves would have been heard than were actually recorded – without this filter, most locations are around airports.

This eliminates most candidate areas, but it still leaves too many to manually check. The shape of the Doppler curve also provides a clue, though. The height of the curve is determined by the airplane’s speed, and the length by its distance. From an aircraft’s flight path, it’s possible to reconstruct the Doppler curve which would have been heard at any point around its flight path. These reconstructions can then be matched against the real curve to find the exact location. In a test, even a single Doppler curve was enough to locate a video without the help of any other clues.

This is just the latest in a long series of unexpected ways in which we’ve seen secrets shared, whether the secret in question is the location of a military base or the position of radar emitters.

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A Smart Alarm Clock That Doesn’t Sell Your Soul

November 8, 2026 by 8 Comments

Devices from the likes of Google and Amazon can be used as high-tech alarm clocks that can show the weather and family photos in addition to telling you what time it is. But they’re also used to push ads out and potentially do other shady things that you’d probably just as soon not have in your bedroom.

If you like the features offered by devices like these but not the hidden costs that come with them, take a look at Rouse. This firmware, which can be installed on common ESP32 development boards such as the Waveshare ESP32-S3-Touch and the ubiquitous Cheap Yellow Display, provides some of those same features in a DIY package.

There’s no user account, no subscription, and no app for your phone that will inevitably stop working some day. The firmware offers up a web interface for configuration that can be accessed by anything with a web browser, and while it can perform firmware updates over the network, it only does so with your approval. It might seem odd that we have to double check to make sure our alarm clocks aren’t leaking any of our information onto the Internet, but that’s the world we live in apparently.

In addition to the basic ESP32 board, you’ll probably want to add some buttons and a speaker, all of which is documented in a fantastic build guide. There’s even files for you to 3D print your own enclosure for the finished clock, though you could certainly put it in an enclosure of your own choosing should you want to customize the build further.

Hackers and makers love clock projects, and at this point we’ve covered more than we can even keep track of. As part of that we’ve seen a number of alarm clocks builds, but as is so often the case around these parts, they tend to be one-off builds. The fact that Rouse has been built with community in mind really makes it stand out, and we’d love to hear in the comments if any of you already have one of these ticking away on your nightstand.

Saving A Vintage High-Voltage Power Supply From The Scrap Heap

November 8, 2026 by 1 Comment

[Mr Carlson’s Lab] saves a Fluke Model 407 high-voltage power supply from the scrap heap, and demonstrates carefully troubleshooting the vintage device to track the cause of the bad output down to a single capacitor. In the process, we get a close look at what is inside as well as insights on how to meaningfully service a device like this.

Firing up old electronics should always be done with care. Some electronic components don’t age well, and some faults aren’t always visible. Applying full power to an vintage device could cause considerable (and avoidable) damage. [Mr Carlson] powers up the device using an isolated transformer and a current-limited variac, but another classic approach would be to use a dim-bulb tester, which most folks could cobble together from spare parts.

Glorious vacuum tubes where one would otherwise expect transistors.

While destined for the junk heap, this Fluke Model 407 actually looks to be in pretty good condition. There’s no obvious damage or failure in its vacuum-tube-and-circuit-board internals, and it powers up but the main output doesn’t act right.

[Mr Carlson] walks through the entire process of tracking down the fault, demonstrating everything from safe power-up and basic inspections to signal and component checking. This process is aided by having access to the original schematics, and the problem is ultimately narrowed down to a faulty capacitor in a feedback signal responsible for keeping the output voltage constant.

It’s not a full restoration, but rather a clear demonstration of diagnosing a hardware error thanks to a careful and informed approach that keeps the specific challenges of vintage electronics in mind. Watch the whole thing in the video, embedded below.

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Space Invaders On A VFD

November 8, 2026 by 8 Comments

When most people think of vacuum fluorescent displays (VFDs), they probably imagine the clock on a microwave or the equalizer on a piece of stereo equipment. But there was a brief period where the glowing phosphor displays were actually used for portable game systems before things like LCD took over.

While the salvaged display that [José Luis Monteiro] and his father have been hacking on certainly isn’t portable, it does play a mean Space Invaders. It’s vertical resolution is a bit tight for the gameplay, but the various sprites look fantastic and the art style works particularly well with the retro VFD vibe.

Just as with their recent efforts to bring Snake to a seven-segment display, a great deal of attention is given to explaining the nuts and bolts of how these vintage displays work. The documentation and source code they’be provided are certainly valuable to anyone else who might be hacking on this type of hardware, but the video they’ve produced is entertaining and informative enough that it’s worth checking out even if you aren’t actively trying to port DOOM over to your old microwave.

If you’re interested in learning even more about these fascinating old school displays, we’ve previously covered some excellent deep dives into the tech.

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Lillith Tells Your Future

November 8, 2026 by 6 Comments

Maybe you are old enough to remember Zoltar in an arcade, or perhaps you’re just a fan of the movie Big. Either way, maybe you’d like to build an animated fortune teller. [Oh Well Why Not] did just that and gives you a roadmap for you to make your own. It took four months to build, but with the road already mapped, you can probably do it in less. Then again, who can predict the future?

The fortune teller, Lillith, uses servos and some voice generation to provide the same experience. If you dare to hit the button, you’ll get a glimpse into your future that’s at least as good as a fortune cookie from your local takeaway place.

Lillith doesn’t hide behind windows since it isn’t in a public venue, but if you were going to put it out in the wild, you’d probably want to encase it a little better. While waiting, the servos provide some small animations to attract the next user.

If you remember Bullwinkle more fondly than Zoltan, you might prefer this project.

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Custom Game Boy Cart Speeds Up Development

November 8, 2026 by 5 Comments

These days, it is easy enough to get a flash cart for your Game Boy that makes it easy to run code — yours or otherwise — on it, but they aren’t necessarily ideal for actual development. The process of shuttling new code over to the cart via an SD card isn’t bad if you’re doing it once, but it gets very annoying if you’re trying to make rapid incremental changes.

Which is specifically what [MrFrenchLame] was looking to improve on with his development cart. Rather than using a SD card to move over ROMs, the cart features a small bootloader that establishes communication with the computer over the Game Boy’s link port. The new code goes right into the cart’s RAM, where it can be immediately executed without having to write it out to flash. When you want to load new code, just press a button on the cart, and the whole thing starts over fresh. The upload routine can even be worked into your IDE to streamline the process.

This lack of permanence makes the cart a poor choice for actually playing games since everything goes poof when the power goes out. Plus, it only has 32K of RAM to work with, and can’t really do anything without being tethered to a computer. But it’s a fantastic solution if you’re looking to test things out quickly.

That said, there is one pretty major problem with this project: it requires your development computer to have a physical parallel port, which is a tall order in 2026. [MrFrenchLame] mentions this could likely be addressed by pulling in knowledge from some of the modern DIY flash carts we’ve seen recently, but hasn’t had time to tackle it yet. Maybe you could lend a hand?

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An FPGA Version Of The AT&T UNIX PC For MiSTer

November 8, 2026 by 9 Comments

We all have our childhood heroes, which in the case of [Hrvoje Cavrak] was the 1985 AT&T UNIX PC. This 18 kg behemoth of a workstation computer boasted a 10 MHz Motorola 68010 CPU, up to 4 MB of RAM and dozens of megabytes of storage in addition to endless expansion options, making it a powerhouse of a personal computer for the discerning professional. Now, many decades later [Hrvoje] has an FPGA-based version to tinker with.

This project targets the MiSTer project, meaning that this softcore with SystemVerilog, Verilog and VHDL components should synthesize and run on any MiSTer-compatible FPGA system, such as the DE10 Nano. For that board the SDRAM add-on board is required due to the DE10 Nano Cyclone V SoC’s FPGA side only having access to a fraction of the 4 MB required by the softcore.

Obviously the boot ROM and disk images for AT&T UNIX are still under copyright, so although you can download both you should be wary of provoking the current copyright holder. With that in place, however, you now have got access to a very complete UNIX PC experience, as can be seen in the demonstration video.

Some aspects of the code were written and validated by LLM coding chatbots, so this is still a ‘works on my MiSTer board’ project. In lieu of getting access to the real hardware – meanwhile priced at unobtanium levels – this seems like a fair enough trade-off if old workstations like these are your thing.

The UNIX PC obviously didn’t make it into mainstream computer as we covered previously, with the IBM PC with MS-DOS, CP/M and Apple’s systems quickly cornering the home market along with Commodore, Atari, etc. This possibly makes these AT&T UNIX PCs even more rare than 1990s SGI and Sun systems.

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