Static Electricity Remembers

As humans we often think we have a pretty good handle on the basics of the way the world works, from an intuition about gravity good enough to let us walk around, play baseball, and land spacecraft on the moon, or an understanding of electricity good enough to build everything from indoor lighting to supercomputers. But zeroing in on any one phenomenon often shows a world full of mystery and surprise in an area we might think we would have fully understood by now. One such area is static electricity, and the way that it forms within certain materials shows that it can impart a kind of memory to them.

The video demonstrates a number of common ways of generating static electricity that most of us have experimented with in the past, whether on purpose or accidentally, from rubbing a balloon on one’s head and sticking it to the wall or accidentally shocking ourselves on a polyester blanket. It turns out that certain materials like these tend to charge themselves positively or negatively depending on what material they were rubbed against, but some researchers wondered what would happen if an object were rubbed against itself. It turns out that in this situation, small imperfections in the materials cause them to eventually self-order into a kind of hierarchy, and repeated charging of these otherwise identical objects only deepen this hierarchy over time essentially imparting a static electricity memory to them.

The effect of materials to gain or lose electrons in this way is known as the triboelectric effect, and there is an ordering of materials known as the triboelectric series that describes which materials are more likely to gain or lose electrons when brought into contact with other materials. The ability of some materials, like quartz in this experiment, to develop this memory is certainly an interesting consequence of an otherwise well-understood phenomenon, much like generating power for free from static electricity that’s always present within the atmosphere might surprise some as well.

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A 100-Year-Old Electronic Musical Instrument Brought Back To Life

In the early years of electrification, when electricity was beginning to shape the modern world, this new technology was being put to use in many more places than turning motors and providing lighting. Some things we can see as obvious missteps like electrified corsets marketed as health tonics or x-ray treatments for eye strain, but others ended up being fascinating bits of technology with interesting uses, many of which have been largely forgotten since. This 100-year-old musical instrument is squarely in the latter category, and this build brings the sound of it back to life.

The instrument was called the Luminaphone and was originally built by [Harry Grindell Matthews]. Of course, this was an age before transistors and many other things we take for grated, so it has some quirks that we might not otherwise expect from a musical instrument. The device generated sound by shining a series of lights through a perforated rotating disc at a selenium cell. The selenium cell was an early photoresistor, generating current corresponding to the amount of light falling on it. A keyboard activated different lights, shining on areas of the disc with different numbers of holes, causing differing sounds to be produced by the instrument.

The recreation was built by [Nick Bild] and uses a laser diode as a stand-in for the rotating disc, but since it can be modulated in a similar way the idea is that the photodiode used as a receiver would generate a similar sound. The recreation sounds a bit like a video game from the 8-bit era, but with no recordings or original Luminaphones surviving to the present day we may never know how accurate it is. There are some other electronic instruments still around today, though, and plenty of ways of DIY-ing their sound like this project which recreates the tonewheels of the classic Hammond organ.

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ice forming on surface with plus and minus pole

The Coolest Batteries You’ve Never Heard Of

Imagine cooling your building with the same principle that kept Victorian-era icehouses stocked with lake-frozen blocks, but in modern form. That’s the idea behind ice batteries, a clever energy storage hack that’s been quietly slashing cooling costs across commercial buildings. The invention works by freezing water when energy is cheap, and using that stored cold later, they turn major power hogs (air conditioning, we’re looking at you) into more efficient, cost-effective systems.

Pioneers like Nostromo Energy and Ice Energy are refining the tech. Nostromo’s IceBrick modules pack 25 kWh of cooling capacity each, install on rooftops, and cost around $250 per kWh—about half the price of lithium-ion storage. Ice Energy’s Ice Bear 40 integrates with HVAC systems, shifting up to 95% of peak cooling demand to off-peak hours. And for homes, the Ice Bear 20 replaces traditional AC units while doubling as a thermal battery.

Unlike lithium-ion, ice batteries don’t degrade chemically – their water is endlessly reusable. Combining the technology with this hack, it’s even possible in environments where water is scarce. But the trade-off? They only store cooling energy. No frozen kilowatts for your lightbulbs, just an efficient way to handle the biggest energy drain in most buildings.

Could ice batteries help decentralize energy storage? They’re already proving their worth in high-demand areas like California and Texas. Read the full report here and let us know your thoughts in the comments.

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Kites Fill Electricity Generation Gaps

Looking at a wind turbine from first principles, it’s essentially a set of wings that generate lift in much the same way an airplane wing does. Putting the wings on a rotor and calling them “blades” is not a huge step away from that. But there’s no reason the wing has to rotate, or for that matter be attached to a fixed platform, in order to generate electricity. Anything that generates lift can be used, and this company is demonstrating that with their kite-powered wind generators.

Like other wind energy producers that have used kites to generate electricity, this one is similar in that the kite is flown in a figure-8 pattern downwind where it can harness energy the most efficiently, pulling out a tether which is tied to a generator. When fully extended, it is flown to a position where the wind doesn’t strike the kite as strongly and the tether is reeled in. Unlike other kite generators we’ve seen, though, this one is offered as a turnkey system complete with battery backup and housed in a self-contained shipping unit, allowing it to be deployed quickly to be used in situations where something like a diesel generator would be impossible to get or where the fuel can’t be obtained.

The company, called Kitepower, does note that these aren’t replacements for traditional wind turbines and would be used more for supporting microgrids. There are still some advantages to using kites over fixed turbine blades though: kites can reach higher altitude where the wind is stronger, and they require less materials for a given amount of energy production, often making them even more environmentally friendly and possibly more economical as well. Surprisingly enough, kites can also be used to generate energy even in places where there’s no wind at all.

Monitoring Energy Use And Saving Money

On the surface, the electric grid might seem like a solved piece of infrastructure. But there’s actually been a large amount of computerized modernization going in the background for the past decade or so. At a large scale this means automatic control of the grid, but for some electric utility customers like [Alex] this means the rates for electricity can change every hour based on demand. By keeping an eye on the current rate, you can extract the most value from these utilities.

[Alex] is located in the United Kingdom and has an energy provider whose rates can change every half hour. This information is freely available well enough in advance to download the data and display it visibly in with a NeoPixel LED ring around a clock. The colors displayed by the LEDs represent an increase or decrease in price for the corresponding time and allow him to better plan out the household’s energy use for the day. The clock uses a TinyPICO ESP32 module to gather the data and handle the clock display. A second wall-mounted device shows real-time energy readings for both gas and electricity using two old analog voltmeters modified to display kilowatt-hours.

While not everyone has a utility which allows this sort of granularity with energy pricing, having one can make a bit of a difference as electricity rates under this system can sometimes go negative. [Alex] estimates that using these two displays to coordinate his energy usage has saved around £50 a month. Even if your utility offers minimal or no price adjustments for time-of-use, it’s still a good idea to monitor energy use in your home. Here’s a fairly comprehensive project that does that without modifying any existing wiring.

Hackaday Prize 2023: Machining Metals With Sparks

Working with metals can present a lot of unique challenges even for those with a fairly well-equipped shop. Metals like aluminum and some types of steel can be cut readily with grinders and saws, but for thick materials or some hardened steels, or when more complex cuts need to be made, mechanical cutting needs to be reconsidered in favor of something electric like electrical discharge machining (EDM) or a plasma cutter. [Norbert] has been on the path of building his own EDM machine and walks us through the process of generating a spark and its effects on some test materials.

Armed with a microscope, a homemade high-voltage generator, drill bit, and a razor blade to act as the workpiece, [Norbert] begins by experimenting with electrical discharges by bringing the energized drill bit close to the razor to determine the distance needed for effective electrical machining. Eventually the voltage is turned up a bit to dive into the effects of higher voltage discharges on the workpiece. He also develops a flushing system using de-ionized water, and then finally a system to automate the discharges and the movement of the tool.

While not a complete system yet, the videos [Norbert] has created so far show a thorough investigation of this metalworking method as well as some of the tricks for getting a setup like this working. EDM can be a challenging method for cutting metal as we’ve seen before with this similar machine which uses wire as the cutting tool, but some other builds we’ve seen with more robust electrodes have shown some more promise.

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Automatic Transfer Switch Keeps Internet Online

Living in a place where the electric service isn’t particularly reliable can be frustrating, whether that’s because of a lack of infrastructure, frequent storms, or rolling blackouts. An option for those living in these situations is a backup generator, often turned on and connected by an automatic transfer switch. These are necessary safety devices too; they keep power lines from being back-fed by the generators. But there are other reasons to use transfer switches as well as [Maarten] shows us with this automatic transfer switch meant to keep his computers and Internet powered up.

The device is fairly straightforward. A dual-pole, dual-throw relay is housed inside of an electrical junction box with two electrical plugs, each of which can be connected to a different circuit or power source in [Maarten]’s house. The relay coil is energized by the primary power supply, and when that power is lost the relay automatically changes over to the other power supply, which might be something like a battery backup system. [Maarten] was able to get a higher quality product by building it himself rather than spending a comparable amount of money on a cheap off-the-shelf product as well. Continue reading “Automatic Transfer Switch Keeps Internet Online”