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Converting AC Irrigation Valves To DC Operation

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Due to historical engineering decisions made many decades ago, a great many irrigation systems rely on solenoid valves that operate on 24 volts AC. This can be inconvenient if you’re trying to integrate those valves with a modern smart home control system. [Johan] had read that there were ways to convert these valves to more convenient DC operation , and dived into the task himself. As [Johan] found, simply wiring these valves up to DC voltage doesn’t go well. You tend to have to lower the voltage to avoid overheating, since the inductance effect used to limit the AC current doesn’t work at DC. However, even at as low as 12 volts, you might still overheat the solenoids, or you might not have enough current to activate the solenoid properly. The workaround involves wiring up a current limiting resistor with a large capacitor in parallel. When firing 12 volts down the line to a solenoid valve, the resistor acts as a current limiter, while the parallel cap is initially a short circuit....
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Keebin’ with Kristina: the One with the Height-Adjustable Key Caps

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Now, we can’t call these LEGO key caps for obvious reasons , but also because they don’t actually work with standard LEGO. But that’s just fine and dandy, because they’re height-adjustable key caps that use the building block principle. Image by [paper5963] via reddit Now you could just as easily build wells as the dome shape pictured here, and I’d really like to see that one of these days. In the caption of the gallery, [paper5963] mentions foam. As far as I’ve studied the pictures, it seems to be all 3D-printed material. If they were foam, they would likely be porous and would attract and hold all kinds of nastiness. Right? [paper5963] says that there are various parts that add on to these, not just flat tops. There are slopes and curves, too. They are also designing these for narrow pitch, and say they are planning to release the files. Exciting! Fold-able Keyboard Goes Anywhere [pinya] says this is a remake of their Crabapplepad V2 into something that folds. They take it ...
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Kodak MC3: Everything But a Phone In 2001

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One of the constants in consumer electronics is that designers will try to put as many features into a single device as possible, whether it’s a Walkman with a radio tuner or a new class of devices that crams a photo and video camera in the same enclosure as a music player. At the time that the Kodak MC3 was released this made it a rather unique device, with it in hindsight being basically a smartphone without the phone, as [Tech Tangents] aptly notes in his recent video on the device . Six years before Apple’s iPhone would be announced, and eight years before the first iPod with a video camera, the Kodak MC3 was in many respects bleeding edge technology targeted straight at tech enthusiasts. For less than $300 you got VGA-quality images, CompactFlash storage, and MP3 playback capability. The videos it produced were 320×240 resolution, h.263 encoded MOVs with a maximum length of 4 seconds at 20 FPS, or 4 minutes with a 64 MB CF card. The unit that [Tech Tangents] got used came with...
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Hackaday Links: February 8, 2026

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We start this week with a bit of a good news/bad news situation. On February 6th, the Relativistic Heavy Ion Collider (RHIC) was shut down  after 25 years of operation . Located at Brookhaven National Laboratory in Upton, New York, the RHIC was the only operating particle collider in the United States, and along with the Large Hadron Collider (LHC), was one of only two heavy-ion colliders in existence. So that’s the bad news. The good news is that the RHIC is going dark so that the Electron-Ion Collider (EIC) can take its place. Planned for activation in the mid-2030s, the EIC will occupy the same tunnel as the RHIC and reuse much of the same hardware. As the name implies, it will be used to collide electrons. Switching gears (no pun intended) to the world of self-driving cars, Waymo’s chief safety officer, Dr. Mauricio Peña, made a surprising admission this week during a U.S. Senate hearing . When asked what his company’s vehicles do when they are presented with a situation t...
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Wooden Case Makes a 2026 TV Stylish

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The middle of the 20th century produced a revolution in understated stylish consumer design, some of which lives on today. The reality of living in a 1950s or ’60s house was probably to be surrounded by the usual mess of possessions from many past decades, but the promise was of a beautiful sleek and futuristic living space. Central to this in most homes would have been the TV set, and manufacturers followed the trends of the age with cases that are now iconic. Here in 2026 we put up with black rectangles, but fortunately there’s Cordova Woodworking with a modern take on a retro TV cabinet. We’ve put the build video below , and it’s a wonderfully watchable piece of workshop titillation in a fully-equipped modern shop. While we appreciate they’ve put the design up for sale, we think many Hackaday readers could come up with their own having already been inspired. One thing we notice over the originals is that they use “proper” wood for their case, when we know the ’60s version would ha...
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Habit Detection For Home Assistant

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Computers are very good at doing exactly what they’re told. They’re still not very good at coming up with helpful suggestions of their own. They’re very much more about following instructions than using intuition; we still don’t have a digital version of Jeeves to aid our bumbling Wooster selves. [Sherrin] has developed something a little bit intelligent, though, in the form of a habit detector for use with Home Assistant. In [Sherrin]’s smart home setup, there are lots of things that they wanted to fully automate, but they never got around to implementing proper automations in Home Assistant. Their wife also wanted to automate things without having to get into writing YAML directly. Thus, they implemented a sidecar which watches the actions taken in Home Assistant. The resulting tool is named TaraHome. When it detects repetitive actions that happen with a certain regularity, it pops up and suggests automating the task. For example, if it detects lights always being dimmed when medi...
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555-Based Square-Wave and Triangle-Wave Function Generator Build for Beginners

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Over on YouTube [Andrew Neal] has a Function Generator Build for Beginners . As beginner videos go this one is fairly comprehensive. [Andrew] shows us how to build a square-wave generator on a breadboard using a 555 timer , explaining how its internal flip-flop is controlled by added resistance and capacitance to become a relaxation oscillator. He shows how to couple a potentiometer to vary the frequency. He then adds an integrator built from a TL082 dual op amp to convert the circuit to a triangle-wave generator, using its second op amp to build a binary inverter. He notes that a binary inverter is usually implemented with a comparator, but he uses the op amp because it was spare and could be put to good use. Again, potentiometers are added for frequency control, in this case a 1 MΩ pot for coarse control and a 10 kΩ pot for fine control. He ends with a challenge to the viewer: how can this circuit be modified to be a sine-wave generator? Sound off in the comments if you have some...
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