Kritik sah

If the word “train” didn’t grab your attention, you’re probably not the target audience for this project. If it did, then there is no need to explain why [AeroKoi] has come up with a modular 3″ train whistle, available on Thingiverse and well explained in the video embedded below. It’s a train whistle. Who doesn’t want their own train whistle? The great part of this design– aside from requiring less air than his earlier, larger-diameter iterations –is the modularity. With adjustable bell caps, you can alter the size of the resonant chamber and thus the notes the whistle plays on the fly. That’s the key difference between a train whistle, as used in the steam era, and a train horn as you find on a modern diesel or electric– whistles use a resonant chamber, while a horn uses a diaphragm to create the vibrations we call sound. By using the movable chamber caps to change the resonance, you can go from a Santa Fe 5 chime to...

Although combining electronics and 3D-printed structures is fairly common, this usually entails some level of manual assembly. This contrasts strongly with the Print & Place approach demonstrated by [Oliver Child] et al. in their research article titled Print & Place: Using a 3D printer for Continuous Assembly of Electronic Devices . An accompanying video is also provided which covers all the basics and showing a few ways in which a regular FDM printer can be used without modifications to embed these components. Rather than requiring a custom tool head the thermoplastic is used as a temporary adhesive to pick up parts that are placed in a printed tray elsewhere on the build plate. This parts tray is created parametrically before being printed. Following this an operator has to populate this tray with the requisite parts so that the print head can pick them up when they are needed. This is done during the printing of the actual parts, with regular G-code added to move the he...

Although it used to be a much more rare event, now almost any time at dawn or dusk, provided clear weather, a human observer can walk outside, look up, and spot an artificial satellite passing overhead. This has caused some consternation among astronomers who have another source of pollution to deal with in their data, but has benefited society in other ways such as more reliable internet and better weather predictions. To keep an eye on what exactly is passing overhead, take a look at this tool built by [Armaan] . The browser-based satellite tracker uses simplified perturbations models (SGP4) to model the passes of every satellite that has passed a given location on Earth in the past seven days. The modeling is all done locally within the user’s browser, and can even be self-hosted through a fairly simple method that involves forking the project with a tool called Vercel. Not only does this tool find the satellite passes for that given location, though, but it also automaticall...

Back in 2002, [Takahiro Yonemura] and others built a system that used a single webcam-like device to track a user’s hand and generate inputs for a computer. Given that this was more than 20 years ago, the technological limitations were much greater than they are today. It wasn’t until nearly a decade later that we got something like the Microsoft Kinect, and even now many VR and gesture controls require something more than a simple camera. Although [Takahiro Yonemura]’s original paper (Japanese, Google Translate link ) is now many decades old, he’s recently picked the project back up and used it to develop this game . The original system worked by attempting to automatically identify the user’s fingers and head. The team had focused on user inputs for standard PCs, drawing characters in the air and allowing the software to interpret them and pass them to a computer. In the modern iteration the scope is slimmed down a bit. The system instead detects an ope...

Over the past decades CRISPR, short for “clustered regularly interspaced short palindromic repeats”, has become somewhat of a household name, holding the promise of directly addressing genetic mutations by effectively removing, silencing, or even fixing them. Yet the original purpose of CRISPR is slightly less cute and cuddly: the evolutionary origin of these DNA sequences is that of a core component of the prokaryotic immune system. In most medical applications today we only try to use CRISPR to detect sequences and then apply enzymes such as the well-known Cas9 to cut DNA at specific locations in the process of gene-editing. In a recent study (paywalled, bioRxiv pre-print ) by Jingkun Zheng et al. in Nature such benign enzymes are dropped for Cas12a2, which turns a detection event into the release of a DNA-destroy enzyme as the molecular equivalent of a guided missile. The pitched use case here is the detection of cancer-cell specific mutations in the DNA, following wh...

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...

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...