Mysterious Files PH

If you look around your environment, you can probably pick off quite a few things that you’ve made, at least if you’ve been at this a while. You probably aren’t reading this from the bottom of a body of water though, which means you lack the incredible confidence of submarine builder [Hank Pronk]. Not only is he building himself a capable-looking diesel-electric submarine over on YouTube, he’s even DIYing CO2 scrubbers for it! Yeah, that’s a man who believes in himself.

Luckily [Hank] is not anywhere near the Caribbean, so needn’t worry about being misidentified as a narco-sub, but he still has to be concerned about his oxygen supply when tooling around beneath the local lakes. Perhaps more important than the oxygen supply in a sub is the build up of CO2. It doesn’t matter how many oxygen tanks you bring down with you if you can’t scrub CO2 out of the air to make room for it. Just like the Apollo missions, he’s using a chemical adsorbent to take carbon dioxide out of the air — and just like Apollo 13, he’s switching from square to round.

Or, rather, from a rather rectangular commercial model to a DIY little round unit. That’s because he doesn’t need the big scrubber in this sub: being diesel-powered, he expects to spend a lot of time at snorkel depth, where both the pilot and the engines can get clean air through the tube. Dives are expected to be short, and in that use case, too big of a CO2 scrubber is really a waste. If for some reason he gets stuck on the bottom, well, the lake isn’t that deep. He can swim to surface, and has a detailed bailout plan. If he wants to stay under overnight to avoid bailing at night, he’s carrying enough extra adsorbent for that.

There’s a reason almost every submarine we’ve featured on this site over the years is an ROV. It’s not that a homemade submarine is automatically a death trap, but you sure do have to be confident in your design.

When it comes to robots, few are as iconic as Robby. [Ogrinz Labs] has wanted to build one and even examined a real one up for auction to get high-res photos of it. He also combined his designs with some other open-source designs, and it looks good. He’s released his design as a Creative Commons-licensed set of STL files that you, in theory, could print. There are more details and instructions in the video below.

If you are looking for something quick to print for the weekend, this isn’t it. As you might expect, this is a lot to print. The creator admits, too, that it isn’t totally accurate. It has bigger feet, for example, so his feet can fit inside. There are a few other modifications made for different reasons, but only a hard-core Robby enthusiast would notice any of them.

In theory, you can wear the robot as a costume, but at the current height, it doesn’t look like that will work for the creator. Also, the joints that would make things rotate are still forward work, but he’s promised to provide updates.

Robby started out on Forbidden Planet and went on to appear in many other movies and TV shows. Much of the original body was vacuum-formed plastic (an early form of ABS known as Royalite).

Thanks to modern slicers, you can easily print the parts on your printer for later assembly, and the video shows you how. You can select what connectors are used, and while we like the dovetail mode for most of what we do, Robby’s clean surfaces need dowel connectors. We would be really excited to see someone take these files and make a working robot based on the design.

We’ve been watching this project for a while. If you are sorry you missed the auction of the original, you aren’t alone. But we couldn’t have afforded the $5,375,000 price tag anyway.

For those of us old enough to remember the harrowing days of the early 2020s, alongside another major kerfuffle there was a complete breakdown in global supply chains that led to the 2020-2023 global chip shortage. Unsurprisingly, this pushed many hardware manufacturers into less orthodox approaches, massive BOM changes, and hurried redesigns. One of the results of this era found its way into the hands of the bloke over at the [Playduino] YouTube channel, who was mystified to find two bodge wires in his fancy Saleae logic analyzer.

The reason for popping open the LA was crosstalk between two channels, which was bad enough that it made the unit quite unusable for the intended task. After seeing the cut traces and bodge wires he initially assumed that since he bought it used that the previous owner had modified it, but said person denied having opened it since purchasing it from an official retailer.

This was when he emailed Saleae support to see whether they knew anything. Initially they denied knowing anything about such a modification, but then the CTO emailed back with a long and very detailed confession. As explained in the video, during the aforementioned chip crisis Saleae was forced to rapidly redesign their LAs to use whatever FPGAs and other parts they could still get their hands on.

An initial prototype unit passed their internal tests, so they had a first batch manufactured using PCBs from a different supplier. Despite sending the same Gerber files, the resulting PCBs had ground fill issues that necessitated the observed rework, but due to insufficient testing for crosstalk a total of 406 units made it into the wild.

Sadly he had to return the defective unit for a replacement, making it somewhat hard to let go of such a piece of history. That said, if you want to know whether you’re also one of the lucky remaining 405 LA owners, the CTO provided the affected serial number range: 00200026245 to 00200026675 are affected.

After recently reviewing a Wattcycle LFP battery sent over by the manufacturer, [Will Prowse] was made aware of some disturbing changes to the internals of batteries received by regular customers. Rather than the nice protected cables, thick solid metal busbars, braided wire and excellent build quality, the units that a regular customer – got as well as the one that [Will] bought off Amazon – all feature something more akin to what you’d find in a budget LFP battery, including a wide variety of LFP cells.

With these LFP batteries generally coming in fully opaque plastic cases, it’s really hard to tell what the internals look like without either going medieval on them or using less intrusive methods such as an X-ray machine. In this case less capable braided cables were replaced with regular cables that in a test showed a much higher voltage drop compared to the braided type.

Along with all the other changes between these batteries, this makes it impossible to rely on any reviews as a customer. [Will] notes that Wattcycle isn’t alone in doing this, and makes the case for more transparent cases for LFP batteries. After all, if you can see at a glance through the transparent case what the cables and wiring looks like, what BMS is installed and even what any LEDs on said BMS PCB are doing.

There are some LFP batteries with such a transparent case already, and with some smaller LFP batteries you can even pop the top off without having to resort to very permanent levels of violence, so this is not a problem without solutions. From a consumer perspective it definitely would be nice to see the internals as literal transparency from the manufacturer’s side, as well as an increased ability to monitor the battery for any thermal, leakage or other issues.

[Trwmato] wanted to spend more time listening to a normal radio to cut back on phone use. But the programming wasn’t quite right so, of course, the solution was to spin up a custom radio station!

The station in question uses a Pi Zero to poll podcasts and news from RSS feeds and automatically mixes them with local content and sends it out via Bluetooth. An FM transmitter allows it to still work on the FM radio, too. Grabbing podcasts isn’t very difficult, thanks to podget. The real logic is in how long to retain things and creating a playlist that both prioritizes fresh content while not repeating things too often. Did we forget to mention the whole thing is a collection of shell scripts?

We could see this as the start of a cool project to have a “radio station” for a school, organization, or company. It is easy to understand and modify.

We often argue that the much-maligned bash script is sometimes the right tool for the job. You can even do things like critical sections in them.

There are plenty of ways to get sound into your house: good old fashioned headphones, the Dolby surround setup we all lusted after back in the day, or the 21st century’s ubiquitous soundbar, with its ‘spatial audio’ magic. Which will work in your space? If you were an audio engineer, you’d set up listening area and use a microphone to map the space– but that would be thousands of points and sounds like tedium. [PlasmatronX] had a better idea: use Schlieren imaging to see the sound waves as the travel through the space. Schlieren imaging has trouble with audio frequencies, though, and imaging the entire living room was going to be difficult. So he scaled it all down– including the sound waves, by shifting to ultrasonic frequencies.

He’s using the usual mirror-and-razor Schlieren setup with an 8″ telescope mirror– and if you don’t know what that is, we did a deep dive on this kind of optical flow visualizer a while back. Inside the circular imaging area where that lets him see density changes, he’s set up what he calls a CAT– Computer Acoustic Tomography– array. It’s a rig on a turntable he can set up ultrasonic transducers on, to match the various speaker setups he wants to test, and turn so he can see from all angles what the scaled-down waves are doing. To capture those waves, which aren’t going to be standing still, he adds a stroboscope. All the ultrasound signals are being generated by a Pi Pico, and are scaled 4:1 in the frequency domain– that is, a high 10kHz whine becomes inaudible 40kHz. Those signals are fed through a DIY 8-channel amp into both ultrasonic transducers and larger ‘cat-repellent speakers’ from AliExpress.

The microcontroller is actually a Pico 2W, which is using its “W” to communicate via Bluetooth with a Pi 4. That SBC is running the camera, the stepper for the turntable, and image processing, along with the timing for the audio signals. After that it’s a matter of setting up a scaled down 7.1 surround setup and itty-bity soundbar, and test it on a (stuffed) guinea pig. Obviously you can see a big difference between the steered beams from the tiny soundbar and the true surround, but how that translates to listening pleasure will be at least somewhat subjective.

What’s less subjective is the obvious effect soft furnishings add to the simulation. Now he doesn’t take the time to find a material that will scale the frequency response of a set of curtains, but we’re not sure how much that matters. At 5kHz or 20kHz, they’re going to deaden sound, and you can see that here, and you can see it’s a much bigger deal for the shaped beams of the soundbar than it is for surround sound. In the end, [PlasmatronX] decides to stick to headphones, but the whole video is very much worth watching, so we’ve embeddded it below. If you want to try it yourself he’s put his code on GitHub.

Thanks to [PlasmatronX] for the tip!

Especially in this era of the Internet, the role of the Internet Archive’s Wayback Machine has become increasingly essential as more and more web content vanishes into the ether or is surreptitiously altered to hide salient details. More recently a new worry has seemingly cropped up in the form of scraping of data for so-called AI systems, or at least that’s part of the excuses being offered for blocking the Wayback Machine’s web crawlers, with [Andrew Deck] and [Hanaa’ Tameez] of [Nieman Lab] detailing the impact and reasons provided.

Some news outlets like The Baltimore Banner insist that they’re only blocking the Wayback Machine crawlers because they are worried that LLM chatbots would otherwise ‘improperly cite’ the source of content, while outlets like The Atlantic have put a blanket anti-scraping policy in place. Meanwhile news outlets are generally happy to let paid commercial news archiving outlets like ProQuest and LexisNexis index their content, showing a potential financial incentive.

Whatever the reasons, the direct effect is that as content is modified or vanishes during for example a system migration, buy-out or bankruptcy, researchers who rely on the Wayback Machine are pretty much forced to rely on paid offerings by ProQuest and kin, without the pure archiving focus and free access to information. It will also leave big holes in what the Wayback Machine can cover in its archives, with news especially becoming very spotty.

Incidentally there’s an ongoing petition over at SaveTheArchive.com which people can sign.