Hackaday Links: June 2, 2024

June 2, 2024 by Dan Maloney 6 Comments

So you say you missed the Great Solar Storm of 2024 along with its attendant aurora? We feel you on that; the light pollution here was too much for decent viewing, and it had been too long a day to make a drive into the deep dark of the countryside survivable. But fear not — the sunspot that raised all the ruckus back at the beginning of May has survived the trip across the far side of the sun and will reappear in early June, mostly intact and ready for business. At least sunspot AR3664 seems like it’s still a force to be reckoned with, having cooked off an X-class flare last Tuesday just as it was coming around from the other side of the Sun. Whether 3664 will be able to stir up another G5 geomagnetic storm remains to be seen, but since it fired off an X-12 flare while it was around the backside, you never know. Your best bet to stay informed in these trying times is the indispensable Dr. Tamitha Skov.

Continue reading “Hackaday Links: June 2, 2024” →

Sound And Water Make Weird Vibes In Microgravity

April 29, 2024 by Donald Papp 1 Comment

NASA astronaut [Don Pettit] shared a short video from an experiment he performed on the ISS back in 2012, demonstrating the effects of sound waves on water in space. Specifically, seeing what happens when a sphere of water surrounding an air bubble perched on a speaker cone is subjected to a variety of acoustic waves.

The result is visually striking patterns across different parts of the globe depending on what kind of sound waves were created. It’s a neat visual effect, and there’s more where that came from.

[Don] experimented with music as well as plain tones, and found that cello music had a particularly interesting effect on the setup. Little drops of water would break off from inside the sphere and start moving around the inside of the air bubble when cello music was played. You can see this in action as part of episode 160 from SmarterEveryDay (cued up to 7:51) which itself is about exploring the phenomenon of how water droplets can appear to act in an almost hydrophobic way.

This isn’t the first time water and sound collide in visually surprising ways. For example, check out the borderline optical illusion that comes from pouring water past a subwoofer emitting 24 Hz while the camera captures video at 24 frames per second.

Retrotechtacular: The Other Kind Of Fallout Show

April 16, 2024 by Dan Maloney 29 Comments

Thanks to the newly released Amazon Prime series, not to mention nearly 30 years as a wildly successful gaming franchise, Fallout is very much in the zeitgeist these days. But before all that, small-F fallout was on the minds of people living in countries on both sides of the Iron Curtain who would have to deal with the aftermath of a nuclear exchange.

“Uwaga! Pył promieniotwórczy“ (“Beware! Radioactive Dust”) is a 1965 Polish civil defense film from film studio Wytwórnia Filmów Oświatowych. While the Cold War turning hot was not likely to leave any corner of the planet unscathed, Poland was certainly destined to bear the early brunt of a nuclear exchange between the superpowers, and it was clear that the powers that be wanted to equip any surviving Polish people with the tools needed to deal with their sudden change in circumstances.

The film, narrated in Polish but with subtitles in English, seems mainly aimed at rural populations and is mercifully free of the details of both fallout formation and the potential effects of contact with radioactive dust, save for a couple of shots of what looks like a pretty mild case of cutaneous radiation syndrome.

Defense against fallout seems focused on not inhaling radioactive dust with either respirators or expedient facemasks, and keeping particles outside the house by wearing raincoats and boots, which can be easily cleaned with water. The fact that nowhere in the film is it mentioned that getting fallout on your clothes or in your lungs could be largely avoided by not going outside is telling; farmers really can’t keep things running from the basement.

A lot of time in this brief film is dedicated to preventing food and water from becoming contaminated, and cleaning it off if it does happen to get exposed. We thought the little tin enclosures over the wells were quite clever, as were the ways to transfer water from the well to the house without picking up any contamination. The pros and cons of different foods are covered too — basically, canned foods dobry, boxed foods zły. So, thumbs up for Cram, but you might want to skip the YumYum deviled eggs.

Dealing with the potential for a nuclear apocalypse is necessarily an unpleasant subject, and it’s easy to dismiss the advice of the filmmakers as quaint and outdated, or just an attempt to give the Polish people a sense of false hope. And that may well be, but then again, giving people solid, practical steps they can take will at least give them some agency, and that’s rarely a bad thing.

Continue reading “Retrotechtacular: The Other Kind Of Fallout Show” →

Building A Tiny Organic Swimming Pool With Natural Filtering

March 24, 2024 by Lewin Day 18 Comments

When we think of swimming pools, we typically think of large fiberglass, plastic, or concrete constructions full of pristine, clear water. They’re usually maintained in this state with the regular addition of chlorine or other chemical. These kill biological stuff and help filter out dirt and other detritus. However, [David] likes to do things differently, as he demonstrates with a tiny plunge pool built inside his greenhouse.

The basic construction starts with digging a hole and building up a wall with concrete and bricks. There’s nothing particularly controversial there. It’s roughly 2 meters by 3 meters by 0.8 meters deep. To help the pool maintain heat, there’s a layer of foam insulation in the bottom, while the water is held inside a black liner.

Rather than traditional chemical methods, however, [David] relies on organic methods to maintain the pool. He explains how he uses an aquarium pump to create a “bubble filtered” pool that draws water through a gravel bed to maintain it and keep it clear. It’s a very natural setup, with multiple plants in the water to make it as organic as can be. It’s the kind of thing you’d expect to see at a luxury island resort, but [David’s] got one right in his very own greenhouse. [David] explains the organic filtering concept in greater detail on his website.

We’ve featured some pool hacks before, too, though more traditional ones than this. Video after the break.

Continue reading “Building A Tiny Organic Swimming Pool With Natural Filtering” →

A series of plates and tubes sits in a tank of water. The plates are square with what looks to be a white coating.

Desalinating Water With The Sun

December 21, 2023 by Navarre Bartz 12 Comments

Getting fresh water from salt water can be difficult to do at any kind of scale. Researchers have developed a new method of desalinating water that significantly reduces its cost. [via Electrek]

By mimicking the thermohaline circulation of the ocean, the researchers from MIT and Shanghai Jiao Tong University were able to solve one of the primary issues with desalination systems, salt fouling. Using a series of evaporator/condenser stages, the seawater is separated into freshwater and salt using heat from the sun.

Evaporating water to separate it from salt isn’t new, but the researchers took it a step further by tilting the whole contraption and introducing a series of tubes to help move the water along and create eddy currents. These currents help the denser, saltier water move off of the apparatus and down deeper into the fluid where the salt doesn’t cause an issue with the device’s operation. The device should have a relatively long lifetime since it has no moving parts and doesn’t require any electricity to operate.

The researchers believe a small, suitcase-sized device could produce water for a family for less than the cost of tap water in the US. The (paywalled) paper is available from Joule.

If you’re curious about other drinking water hacks, check out this post on Re-Imagining the Water Supply or this previous work by the same researchers.

Re-imagining The Water Supply

October 15, 2023 by Bryan Cockfield 49 Comments

Getting freshwater supplied across cities and towns in a reliable and safe way is no simple task. Not only is a natural freshwater reservoir or other supply needed, but making sure the water is safe to drink and then shipping it out over a dense network of pumps and pipes can cost a surprising amount of time and money. It also hinges on a reliable power grid, which is something Texas resident [Suburban Biology] doesn’t have. But since fresh water literally falls out of the sky for free, he decided to take this matter into his own hands.

The main strategy with a system like this is to keep the rainwater as clean as possible before storage so that expensive treatment systems are less necessary. That means no asphalt shingles, a way to divert the first bit of rain that washes dust and other contaminants off the roof away, and a safe tank. This install uses a 30,000 gallon tank placed above ground for storage, but that’s not the only thing that goes into a big rainwater catchment system like this. A system of PVC pipes are needed both for sending rainwater from the roofs of the buildings into the tank and for pumping it into the home for use. With all of that in place it’s both a hedge against climate change, unstable electric grids, and even separates the user from the local aquifer which may or may not have its own major issues depending on where you live.

While Texas legally protects the rights of citizens to collect and store rainwater, the same isn’t true for all areas. For example, Colorado only just passed a law allowing the collection and storage of a meager 110 gallons of rainwater and forbade it entirely beforehand. There are some other considerations for a project like this too, largely that above-ground systems generally won’t work in cold climates. On the other hand, large systems like these are really only needed where rainfall is infrequent; in more tropical areas like south Florida a much smaller storage system can be used

Continue reading “Re-imagining The Water Supply” →

The Science Behind The Majesty Of Dancing Raisins

September 16, 2023 by Lewin Day 18 Comments

Have you ever thrown a handful of raisins into a tub of sparkling water? Or peanuts into beer? It seems like an altogether strange thing to do, but if you’ve tried it, you’ll have seen the way the raisins dance and tumble in the fluid. As it turns out, there’s some really interesting science at play when you dive into the mechanics of it all. [Saverio Spagnolie] did just that, and even went as far as publishing a paper on the topic.

The fundamental mechanism behind the dancing raisins is down to the bubbles in sparkling water. When dropped into the fluid, bubbles form on the raisins and attach to them, giving them additional buoyancy. They then float up, with some of the bubbles shedding or popping on the way, others doing so at the fluid surface. This then causes the raisins to lose buoyancy, rotate, flop around, and generally dance for our amusement.

[Saverio] didn’t just accept things at face value though, and started taking measurements. He used 3D-printed models to examine bubble formation and the forces involved. Along with other scientists, models were developed to explore bubble formation, shedding, and the dynamics of raisin movement. If you don’t have time to dive into the paper, [Saverio] does a great job of explaining it in a Twitter thread (Nitter) in an accessible fashion.

It’s a great example of cheap kitchen science that can teach you all kinds of incredible physics if you just care to look. Video after the break.

Continue reading “The Science Behind The Majesty Of Dancing Raisins” →