TechyMagThings

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 well.

The build has a few other perks as well. The hardware has wireless communication ability, so it’s easy to keep an eye on when out and about. It can log data and is much more programmable than others. Like most cat feeders, though, it’ll only work for dry food. For automatically feeding wet food something like this robotic feeder that opens cans and dispenses them at set intervals would be needed.

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 thing is very well made, and all of it hand-machined except for off-the-shelf bearings and the yellow side plates, which were commercially CNC’d.

We also appreciate that [This Designed That] took the time to prove the merit of his machine by showing the press in work, and the resulting prints.  We’re not art critics, but we are willing to say this makes a good impression.

[This Designed That] is both printer and machinist, and we’ve seen his print projects before, like using resin prints for foil stamping or a DIY proofing press that seems to share some DNA with this larger project.

Thanks to [Paul Manwaring] for the tip!

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 nonexistent packages or his car’s extended warranty. Dialing out is toddler-friendly, too– it’s as simple as mashing an arcade button linked to the ESP32’s GPIO. Each designated contact gets a button with its pre-programed contact, like the speed dial of yore. A really nice touch is the use of illuminated buttons tied to the time-zone of the designated contact: kiddo will learn quick that if the button isn’t lit, it’s not time for phone calls. The phone will actually say so, via a text-to-speech that also announces network errors and the like.

While cardboard box housing the prototype seems a bit flimsy to trust with any toddler we’ve met, but the concept here is very sound indeed. We’ve seen such kid-communication devices before, but this implementation, aside from being more current, has a lot to recommend it.

Thanks to [Allan Binder] for the tip!

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 NpO₂ to transition metal oxides like Sr₂MgReO₆, 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 assigned to the phonons. This generates pseudo-chiral phonons which then show up in the Raman spectroscopy.

Although finding evidence for octopolar magnetic order is interesting in itself, this way to measuring a crystal lattice’s structure makes for another fascinating research tool that can be used to study many similar phenomenon.

These quantum-level magnetic states could conceivably be used for anything from sensors to magnetic data storage, though any such research is unlikely to be commercialized any time soon.

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 also be one that supports OTA updates as otherwise it won’t have the appropriate logic to exploit.

We’ve seen hacks of various infotainment systems before including older Hyundai systems and Teslas.

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 above the tail with its twin vertical stabilizers. It wasn’t really a shocker to see that the resulting 368 gram light airplane actually flies pretty well, with it taking off almost immediately.

With the used 2S1P, 1300 mAh Li-Po battery total flight time is about 3-4 minutes, which seems about on par with typical numbers. With a larger airplane and battery these two EDFs probably could be pushed even further, which we fully expect to see in a future video.

Sometimes the naming of parts in electronics can contribute to confusion about what they are good for, with the topic of Zener diodes in the context of fast surges like those from electrostatic discharge (ESD) being a good example. In a recent video by [BTT Lab] this particular question regarding Zener suitability for suppressing ESD is addressed, as compared to transient-voltage-suppression (TVS) diodes.

The main argument against using Zener diodes for ESD and similar surge suppression is that they react too slowly, which obviously gives said surge time to cause some real damage. This is where a special form of avalanche effect-based diodes called TVS diodes are recommended, as their response time is in the picoseconds rather than nanoseconds or slower as for Zener diodes.

Although this is technically true, as also pointed out in the video, a Zener diode also uses the avalanche effect, with the diode starting off conducting in the reverse direction using the Zener effect before transitioning to the much faster avalanche effect. The transition point is hereby determined by how heavily the p-n junction is doped, making effectively all Zener diodes also avalanche diodes.

TVS diodes consequently are basically Zener diodes that are optimized for a very early transition to said avalanche effect. They are also generally larger than typical Zener diodes as they generate a lot of internal thermal energy while in reverse conducting mode, which has to be contained and shed without causing permanent damage.

The short version is thus that diodes marked as ‘TVS’ are the best choice for surge protection, while those marked as ‘Zener’ are best used for voltage clamping, reference voltages and all other typical Zener diode things.