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Hackaday Links: October 17, 2021

We found a couple of headlines this week that seemed pretty alarming at first, mentioning as they did both “Chinese grannies” and “stun guns.” Digging a little deeper, it appears that widespread elder abuse isn’t what this is about, although there certainly is an unsavory aspect to the story. Apparently, it’s pretty common in Chinese cities for large groups of people to get together for exercise, with “square dancing” being one popular form. This isn’t the “do-si-do and allemande right” square dancing that made high school gym class really awkward for a few days, but rather large groups of mostly older women busting moves to Chinese music in public spaces. It’s the music that’s bothering some people, enough so that they’re buying “stun guns” that can somehow turn off the dancing grannies’ music. None of the articles go into any detail on the device besides describing it as a flashlight-looking thing, and that it appears to do no permanent damage to the sound system. We’d love to know where to get one of these things — you know, for science. And really, it’s kind of sad that people are taking offense at senior citizens just looking for a bit of exercise and social contact.

A couple of weeks back, we mentioned TeachMePCB, a free online PCB design class designed to take you from zero to PCB designer. We’ve been working through the course material and enjoying it, but it strikes us that there’s a lot to keep track when you’re designing a PCB, especially if you’re new to the game. That’s where this very detailed PCB design checklist would come in handy. It takes you right from schematic review and breadboard testing of subassemblies right through to routing traces to avoid crosstalk and stray capacitance problems, and right on to panelization tips and even how to make sure assembly services get your build right. Reading through the list, you get the feeling that each item is something that tripped up the author (grosdode) at one time or another. So it’s a little like having someone with hard-won experience watching over your shoulder as you work, and that can’t really be a bad thing.

Our friend Jeroen Vleggaar over at Huygens Optics on YouTube posted a video the other day about building an entire Schmidt-Cassegrain reflecting telescope out of a single piece of glass. The video is mostly an interview with optical engineer Rik ter Horst, who took up the building of monolithic telescopes as a hobby. It turns out that one of his scopes will be flying to space aboard a cubesat in January. If you’re a fan of precision optics, you’ll want to check this out. Jeroen also teased that he’ll be building his own version of Rik’s monolithic telescope, so watch for an article on that soon.

Heads up — applications are now being accepted for the Open Hardware Summit’s Ada Lovelace Fellowships. This year there are up to ten fellowships offered, each of which includes a $500 travel stipend to attend the Open Hardware Summit in April. The fellowships seek to foster a more diverse community in open-source hardware; applications are being accepted until December 17th, so hurry.

And finally, if you’ve got some spare cycles, you might want to turn your Mark 1 eyeballs to the task of spotting walrus from space. The World Wildlife Federation (WWF) is crowdsourcing its walrus census efforts by training people to spot the well-armed marine mammals in satellite photos. Assessing population numbers and distribution is important to understanding their ecology, and walrus are cute and cuddly (no, they’re not), so getting people to count them makes sense. But this seems like a job for machine vision — there has to be a model trained to recognize walrus, right? Or maybe just something to count dark spots against a white background? Maybe someone can whip something up to make this job a bit easier and less subjective.

Where You Are Influences What You Invent

[Timon] just bought a new PCB holder setup for his desk. It’s one of those spring-loaded jobbies that uses strong magnets to hold it up off of a work surface, and is made of metal so that you can reflow solder with it. It might be a clone of the PCBite, but frankly I’ve seen similar projects everywhere — it’s hard to say who is copying whom these days. And anyway, that’s not the point.

What struck me about the holders was their tops: they’re repurposed 3D printer nozzles. That’s a fantastic idea because they’re non-magnetic, heat tolerant, relatively uniform, and probably dirt cheap in Shenzhen, where the designer of this board almost certainly lives. Maybe he or she even works in a 3D printer factory? Who knows? But the designer almost certainly looked around for something that would fit the bill, and found the nozzles.

Indeed, there’s been a lot of innovation in all things board-holding coming out of China over the last decade. I can remember when the state of the art was a vise-like affair. (I still like my homebrew Stickvise clone for low, square jobs.)

But with cell phone repairs requiring the ability to hold and reflow ever stranger board shapes, there’s been a flourishing of repositionable holders. The pawn-pillar designs are cool, but their utility rests firmly in how strong the magnets are. (I wouldn’t buy the one linked, for instance, without trying it first-hand.) I really like the look of these jobbies, which have springs to maintain tension. (Will the 3D-printed plastic jaws hold up to multiple reflows?) Anyway, it’s no coincidence that the inventors of these devices are in the cellphone-repair capital of the universe.

The old saying is that necessity is the mother of invention. But what if, like with real estate, it’s location, location, location? You dream up solutions to problems around you, using parts that you’ve got on-hand. If that sounds a little fatalistic, consider that you can also change your surroundings, either physical or even virtual. Are you in the middle of the right challenges and opportunities?

Hackaday Podcast 140: Aqua Battery, IBM Cheese Cutter, Waiting For USB-C, And Digging ADCs

Hackaday editors Elliot Williams and Mike Szczys chew the fat over the coolest of hacks. It’s hard to beat two fascinating old-tech demonstraters; one is a mechanical IBM computer for accurate cheese apportionment, the other an Analog-to-Digital Converter (ADC) built from logic chips. We gawk two very different uses of propeller-based vehicles; one a flying-walker, the other a ground-effect coaster. Big news shared at the top of the show is that Keith Thorne of LIGO is going to present a keynote at Hackaday Remoticon. And we wrap the episode talking about brighter skies from a glut of satellites and what the world would look like if one charging cable truly ruled all smartphones.

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (55 MB)

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This Week In Security: The Apache Fix Miss, Github (Malicious) Actions, And Shooting The Messenger

Apache 2.4.50 included a fix for CVE-2021-41773. It has since been discovered that this fix was incomplete, and this version is vulnerable to a permutation of the same vulnerability. 2.4.51 is now available, and should properly fix the vulnerability.

The original exploit used .%2e/ as the magic payload, which is using URL encoding to sneak the extra dot symbol through as part of the path. The new workaround uses .%%32%65/. This looks a bit weird, but makes sense when you decode it. URL encoding uses UTF-8, and so %32 decodes to 2, and %65 to e. Familiar? Yep, it’s just the original vulnerability with a second layer of URL encoding. This has the same requirements as the first iteration, cgi-bin has to be enabled for code execution, and require all denied has to be disabled in the configuration files. Continue reading “This Week In Security: The Apache Fix Miss, Github (Malicious) Actions, And Shooting The Messenger”

Basics Of Remote Cellular Access: Watchdogs

When talking about remote machines, sometimes we meanĀ really remote, beyond the realms of wired networks that can deliver the Internet. In these cases, remote cellular access is often the way to go. Thus far, we’ve explored the hardware and software sides required to control a machine remotely over a cellular connection.

However, things can and do go wrong. When that remote machine goes offline, getting someone on location to reboot it can be prohibitively difficult and expensive. For these situations, what you want is some way to kick things back into gear, ideally automatically. What you’re looking for is a watchdog timer!

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The Compute Module Comes Of Age: Say Hello To The Real Cutting Edge Of Raspberry Pi

If we wanted to point to an epoch-making moment for our community, we’d take you back to February 29th, 2012. It was that day on which a small outfit in Cambridge put on the market the first batch of their new product. That outfit was what would become the Raspberry Pi Foundation, and the product was a run of 10,000 Chinese made versions of their very first single board computer, the Raspberry Pi Model B. With its BCM2835 SoC and 512 megabytes of memory it might not have been the first board that could run a Linux distribution from an SD card, but it was certainly the first that did so for pocket money prices. On that morning back in 2012 the unforseen demand for the new board brought down the websites of both the electronics distributors putting it on sale, and a now-legendary product was born. We’re now on version 4 of the Model B with specs upgraded in almost every sense, and something closer to the original can still be bought in the form of its svelte stablemate, the Pi Zero.

How Do You Evolve Without Casualties?

The original Pi Model B+ from 2014.
The original Pi Model B+ from 2014. The form factor has had a few minor changes, but hardware-wise the Pi 4 follows this pretty closely. Lucasbosch, CC BY-SA 3.0.

The problem with having spawned such a successful product line is this: with so many competitors and copies snapping at your heels, how do you improve upon it? It’s fair to say that sometimes its competitors have produced more capable hardware than the Pi of the moment, but they do so without the board from Cambridge’s ace in the hole: its uniquely well-supported Linux distribution, Raspberry Pi OS. It’s that combination of a powerful board and an operating system with the minimum of shocks and surprises that still makes the Pi the one to go for after all these years.

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Illustrated Kristina with an IBM Model M keyboard floating between her hands.

Keebin’ With Kristina: The One With The Curved Typewriter

Aerodox Flies on Wireless Wings

Aerodox, a wireless, split keyboard.[Simon Merrett] didn’t know anything about keyboards when he started this project, but he didn’t let that stop him. [Simon] did what any of us would do — figure out what you like, learn enough to be dangerous, and then start fiddling around, taking all that inspiration and making a mashup of influences that suits your needs.

The Aerodox design became a cross between the ErgoDox‘s key layout and the logic and communication of the Redox Wireless, itself a reduced-size version of the ErgoDox. Interestingly, [Simon] chose the ErgoDox’s dimensions and spacing, and not those of the Redox. Like a lot of people out there, I found the ErgoDox to be too big for my hands, mostly in that the thumb cluster is too far away from the mainland. It’s nice to see that it suits some people, though.

[Simon] worked up a custom hot-swap footprint that makes the board reversible, much like the ErgoDox. Each half has an NRF51822 for a brain, and there’s a third one that acts as a receiver. This external NRF board is connected over UART to an Arduino Pro Micro, which acts as the USB HID and runs QMK. It’s an interesting journey for sure, so go dig into the logs.

Continue reading “Keebin’ With Kristina: The One With The Curved Typewriter”