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Determining Location by Listening for Airplanes

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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...
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Cat Feeder Ensures Fed Cats

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Automatic cat feeders are a dime a dozen, largely because this is an easy problem to solve. Dry cat food is easy for machines to manipulate, and the electronics needed to accomplish the task to a bare minimum are plentiful and inexpensive. But just doling out food is only easy part of the problem. [Jason] wanted to make sure that his cats actually ate once the food was dispensed so he added a few extra features to this cat feeder . The main addition to this feeder compared to off-the-shelf models is a weight sensor under the bowl. The feeder metes out a certain amount of food, and then a Raspberry Pi Pico W keeps an eye on the weight of the dish. If it goes down, presumably the cat has eaten all of the food. But just to be sure, an ultrasonic sensor was added beside the bowl to ensure something cat-shaped was there at the same time. There was some issue with this sensor blasting out noise in a cat’s audible range at first, but it seems like that problem has since been solved as w...
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Etching Press Aims To Impress

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There’s an old joke about inviting a girl up to your dorm room to ‘look at your etchings’– but if you’re going to do that, you’d best have some etchings, lest she call your bluff. Even better would be to have prints available, so you might share your hard work with adoring fans. Over on YouTube, [This Designed That] shows building the perfect little etching press   so you need never invite anyone to your room again: you can crank out enough prints on this bad boy to hand out your etchings on a street corner! Crank is the right word, because it’s hand-cranked, with the rollers chain-driven off a separate driveshaft. It works like, well, a roller press: two steel rollers squeeze a plattern holding your inked etching and a of paper together to put an image onto. His choice of an off-cut of steel pipe to use as the top roller is inspired, even if he did have to turn it down quite a bit to get an even radius and smooth surface finish. The whole thin...
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Toddler Phone Calls Family and No One Else

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The great thing about the modern world is how connected we are. It’s also the worst thing about the modern world, to be honest. [Allan Binder] wanted to give his toddler the very best of that, and escape the worst, with a specially-designed telephone to call Grandma with– and not get scam calls in turn. We’re not going to say his build guide is so thorough a toddler could follow it, but it’s not too far off. The device is very simple: a commercial ‘retro-style’ handset pairs with an ESP32-S3 over USB. Said ESP32, aside from acting as a USB host, runs a minimal Session Initiation Protocol (SIP) client, which connects via WiFi to a VoIP account the parent has set up. In this case, [Allan] is using Twilio, but there are other internet telephony providers one could use if a Twilio employee once ran over your dog or something. There are no inbound calls in this setup, so little Timmy isn’t going  to be bothered needlessly about import fees on no...
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Detecting an Eight Magnetic Pole State using Chiral Phonons

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The idea that magnetism doesn’t necessarily always have a dipolar configuration is not a new one, but it’s not an easy theory to find evidence for. Most recently a team of scientists at the University of Toronto used a new method involving vibrational energy in the form of phonons to find evidence for an octupolar magnetic order . In the associated paper in  Physical Review Letters (paywalled, arXiv version ) by [Ruairidh Sutcliffe] et al. we can find more details on this method and what their findings may mean for various fields. Naturally, this is a quantum-level phenomenon that requires Raman spectroscopy to be detectable via said phonons. The materials investigated here are also somewhat exotic, ranging from actinides like NpO 2 to transition metal oxides like Sr 2 MgReO 6 , while having on common strong spin-orbit coupling. Where the phonons come into play is that they can be used to indirectly measure crystal lattice distortions due to the pseudo-angular momentum a...
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NEMESIS Gives You Control Over Your Hyundai Head Unit

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Whether it’s to make more money or because of licensing disagreements, car companies often restrict the abilities of the infotainment units in their vehicles. They can do so much more, and a group of hackers is setting the Gen5W systems from Hyundai free with NEMESIS . Many Hyundai and Kia vehicles from 2015 to 2019 use the Gen5W system, but there are some exceptions to the exploit like the Hyundai Elantra, Kia Forte, and Hyundai Ioniq 6, along with Canadian vehicles using the system. The most interesting feature for most users will likely be the ability to use Android Auto or Apple CarPlay wirelessly as well as bringing turn-by-turn navigation cues from those systems to the driver cluster and heads up display like you get with the built-in, but not so great, OEM navigation system. Using a flaw in the over the air (OTA) update system, the developer says “the version must have S5W_M in it (General Settings > SW Info). S5W_L is not supported.” The head unit must als...
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Flying an RC Airplane with Twin Airblower EDFs

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Shortly after [RCMakerLab] posted his question on potentially equipping an RC airplane with the electronic ducted fans (EDFs) from those airblower devices – are sold mostly as a replacement for canned air – the comment sections pretty much exploded with comments that he should just have strapped them onto an RC airplane and see for himself. In a new video this is exactly what is done , creating a somewhat A-10 Warthog-esque RC plane with its twin EDF turbines. After we first covered this journey, the next question that got answered in the subsequent video was whether replacing the default electronic speed control (ESC) would make sense, mostly to lighten the load and optimize it for use with a typical RC avionics controller.  This turned out to be the case, and thus it’s time for a test flight. The aircraft created from largely styrofoam board seems to be largely designed for stability, with its large wings and the very A-10-like placement of the turbines right abov...
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