Dramatically Increasing Usable Closet Space

As any science YouTuber or first-year physics student is quick to point out, the universe is mostly empty space. Not just space itself, but the amount of “empty” space between nuclei and their electrons is also huge. Getting rid of this empty space results in all kinds of interesting phenomena like degenerate matter and black holes. But the concept can be extrapolated into our daily lives as well; many things are so filled with air that we can get a lot more usable storage space by compressing them down a little bit. [Super Valid Designs] took this concept to a coat closet, building one that can hold an impressive number of coats.

He started by looking at an existing closet, which could hold around 21 coats but only if someone used two hands to cram the coats into the space. After a trip to a store which sells rugs, he saw a much better design that lets all the rugs pivot like the pages on a book, and took this idea to his closet using a similar mechanism designed for storing large blueprints instead of rugs. The closet he built around this mechanism has two hinged doors which allow a person easy access to the coats, and when opened the blueprint hangers pivot out like a book, allowing the coats to not only be easily accessed without disrupting the other coats, but also allow them to be compressed down by the closet door for storage.

For comparison, the original closet could only hold 10 coats when restricted to single-hand operation and 21 when using both. The new closet design is smaller, and can hold 24 coats with a single hand and over 30 when using both, a dramatic improvement of closet efficiency. To top it off, a set of cupboards on top and bottom allow for storing shoes and hats as well, and there’s even a garage for a robotic vacuum cleaner. Surprisingly, we don’t see many closet optimization builds around here. The closest we can come is another traditionally small space, a college dorm.

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A Split Keyboard Designed For Human Hands

A surprising number of things we use in everyday life retain most of their design cues from their 19th century ancestors. The bicycle retains the same basic design as it had in 1890, as does the sewing machine, the toilet, the car, and of course, the keyboard and the QWERTY layout from old typewriters. But we aren’t doomed to have our technology perpetually living in the past. [Paul] wanted a keyboard designed around human hands, rather than being designed around a machine, so he built this unique split keyboard.

The design of this specific keyboard went through around 50 iterations before he was comfortable with it. Other design goals here were for it to be portable, and the split nature of this certainly makes it more compact as does the use of low-profile switches. Each finger’s column is angled and spaced based on the needs of that finger, with the ring finger keys sitting higher and the index finger columns angled inward. Each thumb has access to three keys, one of which is the spacebar and the other two layer keys, which is what enables this design to get down to only 36 total keys.

When thinking about it for any length of time, the modern keyboard’s design holdovers from the 1800s are fairly wasteful compared to this split, ergonomic version. Especially when looking at the spacebar, which ties up both thumbs and only performs a single task, there’s a lot of opportunity for modern designs to be more efficient, more portable, and easier on one’s body. Feel free to take this to the extreme and use all three dimensions, as long as you aren’t particularly concerned with portability.

Miniaturized, Working Replica Of Vintage Leslie Speaker

Few pieces of vintage audio gear from the turn of the century (the previous one) inspire the kind of devotion that a Leslie speaker does. Sure, there are plenty of pieces that are rarer or more valuable, but the Leslie speaker has such a big following because of its uniqueness of physically moving sound around a room. Two rotating devices in the speaker physically direct the sound around the cabinet with musician-controlled speed, and this sound remains extremely difficult to reproduce faithfully without the moving components. But originals are enormous and meant for organs, so [Eric] built a 40% replica with a few modern touches for his guitar.

The build starts with a CAD model, where [Eric] works towards making the most accurate enclosure for his speaker as possible. The CAD model heads out to a CNC machine which can care most of the details into the wood, and he eventually is able to finish it, although it took a few tries with stains and paintbrushes of various types. For the speakers themselves, he’s using modern versions including modern brushless motors to drive the rotating elements. Like the original speaker, the high range of sound is sent through a rotating set of horns, of which one is only a counterweight, and the low range is directed out of the bottom of the cabinet through a large rotating drum. Both rotating elements here are 3D printed, and with everything put together and wired up [Eric] has a much more portable, faithful recreation of the original Leslie speaker.

There are some upgrades in the wiring too, which makes it work better with a guitar rather than for an organ. It’s also much lighter, and was a hit when he took it to let a few other guitarists to play as well. It’s not the first time we’ve seen the Leslie’s movement recreated for guitar, but it is the most alike to the classic 1930s-era speaker we’ve seen so far.

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Tricking An Air Conditioner Into Cooling

Modern heat pumps, of which air conditioners are a subset, seem like simple machines in theory. They just move heat from one place to another. But in order to operate efficiently, they need specific temperatures and humidities on either side of the pump or they can behave in non-ideal ways. [GreatScott!] noticed this when his air conditioner worked well during a heatwave, but started acting anemic once the outside air temperature cooled down. At once point it was barely able to bring his indoor house temperature below the temperature outside, and he went on a deep dive to investigate why this would be and then found a way trick his air conditioner into working outside its designed temperature range.

Many things can cause this behavior, and some of them are indicative of malfunctions like low refrigerant levels or problems with the compressor or control circuitry. But [GreatScott!]’s unit is pretty new so it was unlikely to be something like that. To investigate, he built a circuit with a small heater which is paired to the outdoor heat exchanger’s temperature probe, tricking the control circuitry into working in a different mode. With a few temperature sensors inside and outside, this was enough to kick the air conditioner into high gear and start outputting cold air again.

While noting that we aren’t HVAC experts, there are a few things that could cause this. One of which is high indoor humidity which might be likely for Germany in the summer, or the outdoor condenser needing a certain temperature or pressure range to operate efficiently. Whatever the case, [GreatScott!] decided to remove his creation to keep from inadvertently damaging his air conditioner. It is possible, however, to use a bit of machine learning to find out more about why one’s HVAC system isn’t behaving as well as it should.

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USB-C Adapted For Legacy Sprinkler Systems

In the modern world USB has become a truly universal connector, with its inclusion on almost every major piece of consumer electronics. It has even expanded well beyond things that we’d think of as consumer electronics, like the solenoids on automatic sprinkler systems.

This project comes to us from [Ray Wang] at opensprinkler.org who has been working on various ways of controlling the old sprinkler standards, which generally rely on a 24 VAC power supply to drive solenoids. This tests uses the power available from USB-PD and closely examines four methods of energizing the solenoids: unipolar PWM, dual voltage, synthesizing an AC wave from a DC supply, and producing a bipolar square wave. The bipolar square wave had some interesting results, being able to get pretty close to the behavior of a true sine wave while minimizing the dedrmand on power electronics.

For those working on old sprinkler systems, or many other antiquated systems that still rely on 24 VAC, this project shows that USB can deliver a surprising amount of power in unique ways, and the fact that it’s near-ubiquitous and affordable makes it that much easier to adapt into situations it was never really designed for.

These old sprinkler systems have other ways of working on modern systems as well, like this one which replaces the AC source for a DC one, but with a few caveats.

LLM Moats Quickly Evaporating

In the business world, a moat is a quality of a business that makes it difficult for competitors to take that company’s profits. With how hard it is to train models for large language models (LLMs) and generative AI, it might seem like Anthropic, Open AI, and other LLM companies would have huge moats given the amount of compute it takes to build models. But open source models are quickly draining that moat, and now the only thing standing in the way of a customer using one of these models on their own hardware instead one from the larger companies is physical computing resources. [TerminalBytes] demonstrates a few of these models on personally owned computers to show the current state of the art.

[TerminalBytes] started off running the 27B version of the Qwen3.8 on a Mac Studio with 256 GB of unified RAM, which is plenty for this task. But it’s also enough to benchmark a few different models. Qwen3.6 is compared to 3.8, and then the different quants of each model are also compared. Quants are compressed versions of models that need fewer bits to store weights, meaning that the same models can run in less memory with smaller losses in fidelity. Many of these quants run on machines with 32 GB of RAM or less, encompassing many average gaming PCs. There’s even a 1-bit quant that [TerminalBytes] tested which can easily run on a machine with 16 GB, although with mixed results.

Keep in mind that this is just the current state of affairs with open LLMs. Future versions of these models are likely to optimize the number of tokens produced per unit time, or otherwise increase quality of responses while requiring less computer resources. We don’t really think that the ease of running local models will be the sole reason that the AI bubble pops, though. The fact that not every computer user is running Linux is proof enough of that.

Woodstove Assistant Keeps The Heat On Safely

Those who have never lived in a cold climate might romanticize winters around a fire, keeping warm under blankets while snow gently falls outside. While it certainly can be a cozy experience, using a woodstove comes with a number of pitfalls, and when operated improperly can even cause house-destroying chimney fires. Modern stoves operated properly with properly dried wood make this possibility extremely remote, but it’s still worth keeping an eye on. Reddit user [nas886] built a system called Oru which takes a lot of the guesswork out using one of these pieces of heating equipment.

The real danger of a woodstove isn’t necessarily running the fire too hot, although that can be a problem, but running it too cold. Without full combustion of the wood, flammable creosote builds up on the inside of the chimney which eventually can combust. This system uses a probe placed in the stovepipe to monitor the temperature of the exhaust gasses. If it’s too low an ESP32 notifies [nas886] remotely with with a status LED inside a seperate custom-built walnut enclosure so that more wood can quickly be added or airflow increased to bring up the temperature, and in the case that the fire gets too hot the LED changes to a different color and the air can be closed off a bit.

Woodstoves themselves have quite a bit of variability in the size wood they can burn, the amount they can hold at once, their efficiency, and their thermal mass, so this could find utility for anyone from those with tiny stoves that have to be fed constantly to those trying to get all-night burns in massive units, all without having to constantly sit by the fire and monitor it. [nas886] found initial success selling a few of these custom units and plans to put it into further production as well, but the general idea is not too difficult to replicate for most of us here either.

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