Foil Leyden Jar Helps Bring Crookes Tube To Life

May 23, 2025 by Seth Mabbott 7 Comments

It might be too soon to consider the innards of the old CRT monitor at the back of your closet to be something worth putting on display in your home or workshop. For that curio cabinet-worthy appeal, you need to look a bit further back. Say, about 150 years. Yes, that’ll do. A Crookes tube, the original electron beam-forming vacuum tube of glass, invented by Sir William Crookes et al. in the late 19th century, is what you need.

And a Crookes tube is what [Markus Bindhammer] found on AliExpress one day. He felt that piece of historic lab equipment was asking to be put on display in proper fashion. So he set to work crafting a wooden stand for it out of a repurposed candlestick, a nice piece of scrap oak, and some brass feet giving it that antique mad-scientist feel.

After connecting a high voltage generator and switch, the Crookes tube should have been all set, but nothing happened when it was powered up. It turned out that a capacitance issue was preventing the tube from springing to life. Wrapping the cathode end of the tube in aluminum foil, [Markus] formed what is effectively a Leyden jar, and that was the trick that kicked things into action.

As of this writing, there are no longer any Crookes tubes that we could find on AliExpress, so you’ll have to look elsewhere if you’re interested in showing off your own 19th century electron-streaming experiment. Check out the Crookes Radiometer for some more of Sir Williams Crookes’s science inside blown glass.

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Running DOOM On An Atari ST

May 22, 2025 by Heidi Ulrich 27 Comments

If you grew up with a beige Atari ST on your desk and a faint feeling of being left out once Doom dropped in 1993, brace yourself — the ST strikes back. Thanks to [indyjonas]’s incredible hack, the world now has a working port of DOOM for the Atari STe, and yes — it runs. It’s called STDOOM, and even though it needs a bit of acceleration or emulation to perform, it’s still an astonishing feat of retro-software necromancy.

[indyjonas] did more than just recompile and run: he stripped out chunks of PC-centric code, bent GCC to his will (cheers to Thorsten Otto’s port), and shoehorned Doom into a machine never meant to handle it. That brings us a version that runs on a stock machine with 4MB RAM, in native ST graphics modes, including a dithered 16-colour mode that looks way cooler than it should. The emotional punch? This is a love letter to the 13-year-old Jonas who watched Doom from the sidelines while his ST chugged along faithfully. A lot of us were that kid.

Sound is still missing, and original 8MHz hardware won’t give you fluid gameplay just yet — but hey, it’s a start. Want to dive in deeper? Read [indyjonas]’ thread on X.

Recovering Water From Cooling Tower Plumes With Plume Abatement

May 22, 2025 by Maya Posch 24 Comments

Electrostatic droplet capture system installed on an HVAC condenser. (Credit: Infinite Cooling)

As a common feature with thermal power plants, cooling towers enable major water savings compared to straight through cooling methods. Even so, the big clouds of water vapor above them are a clear indication of how much cooling water is still effectively lost, with water vapor also having a negative impact on the environment. Using so-called plume abatement the amount of water vapor making it into the environment can be reduced, with recently a trial taking place at a French nuclear power plant.

This trial featured electrostatic droplet capture by US-based Infinite Cooling, which markets it as able to be retrofitted to existing cooling towers and similar systems, including the condensers of office HVAC systems. The basic principle as the name suggests involves capturing the droplets that form as the heated, saturated air leaves the cooling tower, in this case with an electrostatic charge. The captured droplets are then led to a reservoir from which it can be reused in the cooling system. This reduces both the visible plume and the amount of cooling water used.

In a 2021 review article by [Shuo Li] and [M.R. Flynn] in Environmental Fluid Mechanics the different approaches to plume abatement are looked at. Traditional plume abatement designs use parallel streams of air, with the goal being to have condensation commence as early as possible rather than after having been exhausted into the surrounding air. Some methods used a mesh cover to provide a surface to condense on, while a commercially available technology are condensing modules which use counterflow in an air-to-air heat exchanger.

Other commercial solutions include low-profile, forced-draft hybrid cooling towers, yet it seems that electrostatic droplet capture is a rather new addition here. With even purely passive systems already seeing ~10% recapturing of lost cooling water, these active methods may just be the ticket to significantly reduce cooling water needs without being forced to look at (expensive) dry cooling methods.

Top image: The French Chinon nuclear power plant with its low-profile, forced-draft cooling towers. (Credit: EDF/Marc Mourceau)

You Can 3D Print These Assistive Typing Tools

May 22, 2025 by Lewin Day 8 Comments

Typing can be difficult to learn at the best of times. Until you get the muscle memory down, it can be quite challenging. However, if you’ve had one or more fingers amputated, it can be even more difficult. Just reaching the keys properly can be a challenge. To help in this regard, [Roei Weiman] built some assistive typing tools for those looking for a little aid at the keyboard.

The devices were built for [Yoni], who works in tech and has two amputated fingers. [Roei] worked on many revisions to create a viable brace and extension device that would help [Yoni] type with greater accuracy and speed.

While [Roei] designed the parts for SLS 3D printing, it’s not mandatory—these can easily be produced on an FDM printer, too. For SLS users, nylon is recommended, while FDM printers will probably find best results with PETG. It may also be desirable to perform a silicone casting to add a grippier surface to some of the parts, a process we’ve explored previously.

The great thing about 3D printing is that it enables just about anyone to have a go at producing their own simple assistive aids like these. Files are on Instructables for the curious. Video after the break.

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Building A Tiny Table Saw

May 22, 2025 by Lewin Day 29 Comments

If you want a regular table saw, you’re probably best off just buying one—it’s hard to beat the economies of scale that benefit the major manufacturers. If you want a teeny one, though, you might like to build it yourself. [Maciej Nowak] has done just that.

The concept is simple enough; a small motor and a small blade make a small table saw. [Maciej] sourced a remarkably powerful 800-watt brushless motor for the build. From there, the project involved fabricating a suitable blade mount, belt drive, and frame for the tool. Some time was well-spent on the lathe producing the requisite components out of steel and aluminum, as well as a stout housing out of plywood. The motor was then fitted with a speed controller, with the slight inconvenience that it’s a hobby unit designed to run off DC batteries rather than a wall supply. Ultimately, though, this makes the saw nicely portable. All that was left to do was to fit the metal top plate, guides, and a suitably small 3″ saw blade to complete the build.

We’ve seen mini machine tools like these before, too. They can actually be pretty useful if you find yourself regularly working on tiny little projects. Video after the break.

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2025 Pet Hacks Contest: Loko Tracks Fido With LoRa And GPS

May 22, 2025 by Tyler August 7 Comments

Some projects start as hacks, and end as products — that’s the case for [Akio Sato]’s project Loko, the LoRa/GPS tracker that was entered in our 2025 Pet Hacks Contest. The project dates all the way back to 2019 on Hackaday.io, and through its logs you can see its evolution up to the announcement that Loko is available from SeeedStudio.

It’s not a device necessarily limited to pets. In fact, the original use case appears to have been a backup locator beacon for lost drones. But it’s still a good fit for the contest none-the-less: at 12 grams, the tiny tracking device won’t bother even the most diminutive of pups, and will fit on any collar at only 30 mm x 23 mm. The “ground station” that pairs with your phone is a bit bigger, of course, but unless you have a Newfoundlander or a St. Bernard you’re likely bigger than fido. The devices use LoRa to provide a range up to 15 km — maybe better if you can loop them into a LoRaWAN. Depending on how often you pin the tracker, it can apparently last for as long as 270 days, which we really hope you won’t need to track a missing pet.

The hardware is based around Seeed’s Wio-E5 LoRa chip, which packages an STM32 with a LoRA radio. The firmware is written in MicroPython, and everything is available via GitHub under the MIT license. Though the code for the mobile app that interfaces with that hardware doesn’t appear to be in the repository at the moment. (There are folders, but they’re disappointingly empty.) The apps are available free on the iOS App Store and Google Play, however.

There’s still plenty of time to submit your own hacks to the Pet Hacks Contest, so please do! You have until May 10th, so if you haven’t started yet, it’s not too late to get hacking.

Hackaday Supercon 2025 Call For Participation: We Want You!

May 22, 2025 by Elliot Williams 11 Comments

We’re tremendously excited to be able to announce that the Hackaday Supercon is on for 2025, and will be taking place October 31st through November 2nd in Pasadena, California.

Supercon is about bringing the Hackaday community together to share our great ideas, big and small. So get to brainstorming, because we’d like to hear what you’ve been up to! Like last year, we’ll be featuring both longer and shorter talks, and hope to get a great mix of both first-time presenters and Hackaday luminaries. If you know someone you think should give a talk, point them here.

The Call for Participation form is online now, and you’ve got until July ~~3rd~~ 10th to get yourself signed up.

Honestly, just the people that Supercon brings together is reason enough to attend, but then you throw in the talks, the badge-hacking, the food, and the miscellaneous shenanigans … it’s an event you really don’t want to miss. And as always, presenters get in for free, get their moment in the sun, and get warm vibes from the Hackaday audience. Get yourself signed up now!

We’ll have more news forthcoming in the next few weeks, including the start of ticket sales, so be sure to keep your eyes on Hackaday.