Day: April 9, 2025

Making Liquid Oxygen: Far From Easy But Worth The Effort

April 9, 2025 by 25 Comments

Normally, videos over at The Signal Path channel on YouTube have a certain vibe, namely teardowns and deep dives into high-end test equipment for the microwave realm. And while we always love to see that kind of content, this hop into the world of cryogenics and liquid oxygen production shows that [Shahriar] has other interests, too.

Of course, to make liquid oxygen, one must first have oxygen. While it would be easy enough to get a tank of the stuff from a gas supplier, where’s the fun in that? So [Shahriar] started his quest with a cheap-ish off-the-shelf oxygen concentrator, one that uses the pressure-swing adsorption cycle we saw used to great effect with DIY O2 concentrators in the early days of the pandemic. Although analysis of the machine’s output revealed it wasn’t quite as capable as advertised, it still put out enough reasonably pure oxygen for the job at hand.

The next step in making liquid oxygen is cooling it, and for that job [Shahriar] turned to the cryocooler from a superconducting RF filter, a toy we’re keen to see more about in the future. For now, he was able to harvest the Stirling-cycle cryocooler and rig it up in a test stand with ample forced-air cooling for the heat rejection end and a manifold to supply a constant flow of oxygen from the concentrator. Strategically placed diodes were used to monitor the temperature at the cold end, a technique we can’t recall seeing before. Once powered up, the cryocooler got down to the 77 Kelvin range quite quickly, and within an hour, [Shahriar] had at least a hundred milliliters of lovely pale blue fluid that passed all the usual tests.

While we’ve seen a few attempts to make liquid nitrogen before, this might be the first time we’ve seen anyone make liquid oxygen. Hats off to [Shahriar] for the effort.

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Ask Hackaday: Vibe Coding

April 9, 2025 by 89 Comments

Vibe coding is the buzzword of the moment. What is it? The practice of writing software by describing the problem to an AI large language model and using the code it generates. It’s not quite as simple as just letting the AI do your work for you because the developer is supposed to spend time honing and testing the result, and its proponents claim it gives a much more interactive and less tedious coding experience. Here at Hackaday, we are pleased to see the rest of the world catch up, because back in 2023, we were the first mainstream hardware hacking news website to embrace it, to deal with a breakfast-related emergency.

Jokes aside, though, the fad for vibe coding is something which should be taken seriously, because it’s seemingly being used in enough places that vibe coded software will inevitably affect our lives.  So here’s the Ask Hackaday: is this a clever and useful tool for making better software more quickly, or a dangerous tool for creating software nobody quite understands, containing bugs which could cause a disaster?

Our approach to writing software has always been one of incrementally building something from the ground up, which satisfies the need. Readers will know that feeling of being in touch with how a project works at all levels, with a nose for immediately diagnosing any problems that might occur. If an AI writes the code for us, the feeling is that we might lose that connection, and inevitably this will lead to less experienced coders quickly getting out of their depth. Is this pessimism, or the grizzled voice of experience? We’d love to know your views in the comments. Are our new AI overlords the new senior developers? Or are they the worst summer interns ever?

Going To The Top With A Raspberry Pi Elevator

April 9, 2025 by 17 Comments

[BorisDigital] was mesmerised by a modern elevator. He decided to see how hard it would be to design his own elevator based on Raspberry Pis. He started out with a panel for the elevator and a call panel for the elevator lobby. Of course, he would really need three call panels since he is pretending to have a three-floor building.

It all looks very professional, and he has lots of bells and whistles, including an actual alarm. With the control system perfected, it was time to think about the hydraulics and mechanical parts to make a door and an actual lift.

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Self-Hosting A Cluster On Old Phones

April 9, 2025 by 34 Comments

The phones most of us carry around in our pockets every day hold a surprising amount of computing power. It’s somewhat taken for granted now that we can get broadband in our hands in most places; so much so that when one of these devices has reached the end of its life it’s often just tossed in a junk drawer even though its capabilities would have been miraculous only 20 years ago. But those old phones can still be put to good use though, and [Denys] puts a few of them back to work running a computing cluster.

Perhaps the most significant flaw of smartphones, though, is that most of them are locked down so much by their manufacturers that it’s impossible to load new operating systems on them. For this project you’ll need to be lucky enough (or informed enough) to have a phone with an unlockable bootloader so that a smartphone-oriented Linux distribution called postmarketOS can be installed. With this nearly full-fledged Linux distribution to work from, the phones can be accessed by ssh and then used to run Kubernetes for the computing cluster. [Denys] has three phones in his cluster that run a few self-hosted services for him.

[Denys] also points out in his guide that having a phone that can run postmarketOS might save some money when compared to buying a Raspberry Pi to run the same service, and the phones themselves can often be more powerful as well. This is actually something that a few others have noted in the past as well. He’s gone into a considerable amount of detail on how to set this up, so if you have a few old smartphones gathering dust, or even those with broken screens or other physical problems where the underlying computing resources are still usable, it’s a great way to put these machines back to work.

Thanks to [mastro Gippo] for the tip!

You Shouldn’t Build An X-Ray Machine, But You Could

April 9, 2025 by 18 Comments

Ever wanted your own X-ray machine? Of course you have! Many of us were indoctrinated with enticing ads for X-ray specs and if you like to see what’s inside things, what’s better than a machine that looks inside things? [Hyperspace Pirate] agrees, and he shows you the dangers of having your own X-ray machine in the video below.

The project starts with an X-ray tube and a high voltage supply. The tube takes around 70,000 volts which means you need a pretty stout supply, an interesting 3D printed resistor, and some mineral oil.

The output display? A normal camera. You also need an intensifying screen, which is just a screen with phosphor or something similar. He eventually puts everything in lead and reminds you that this is a very dangerous project and you should probably skip it unless you are certain you know how to deal with X-ray dangers.

Overall, looks like a fun project. But if you want real credit, do like [Harry Simmons] and blow your own X-ray tube, too. We see people build similar machines from time to time. You shouldn’t, but if you do, remember to be careful and to tell us about it!

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In 2025, The Philly Maker Faire Finds Its Groove

April 9, 2025 by 7 Comments

The first Philadelphia Maker Faire was extremely impressive, and seemed poised to be one of the premier maker events on the East Coast. Unfortunately, it had the misfortune of happening just a few months before COVID-19 made such events impossible. Robbed of all its momentum, the event tried out different venues after the shadow of the pandemic was gone, but struggled to meet the high bar set by that inaugural outing.

But after attending the the 2025 Philadelphia Maker Faire this past weekend, I can confidently say the organizers have moved the needle forward. This year marks the second time the event has been held at the Cherry Street Pier, a mixed-use public space with an artistic bent that not only lends itself perfectly to the spirit of Maker Faire but offers room for expansion in the future. The pier was packed with fascinating exhibits and excited attendees, and when the dust settled, everyone I spoke to was thrilled with how the day went and felt extremely positive about the future of the Faire.

Providing coverage of an event like this is always difficult, as there’s simply no way I could adequately describe everything there was to see and do. The following represents just a few of the projects that caught my eye; to see all that the Philadelphia Maker Faire has to offer, I’d strongly suggest you make the trip out in 2026.

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