Keep Your Back Cool While Others Melt

September 17, 2026 by Jenny List 18 Comments

With an El Niño event in full swing those of us in the northern hemisphere have just had a roasting hot summer, and those in the southern are about to have one. We know what that means, even with the best laid plans the slightest bit of exercise is going to raise a lot of sweat. And if you’re carrying a backpack that means a soaking down your back. Never fear though, because for that one, [Crafterboi] is here with a fan-assisted back protector.

The idea is simple enough, an open framework that sits between you and the backpack, allowing air to flow. If that weren’t enough, there are a couple of 5 volt fans at the top to blow air through the space. It’s printed using PETG, because as he explains, on a really hot day some surfaces can exceed the temperature at which PLA starts to soften.

We like the idea of this project, but what we especially like is that his prototype was made of a pizza box. ten out of ten for resourcefulness! Meanwhile this isn’t the first time we’ve seen a cooling backpack as others have had Peltier systems and evaporative coolers. We would link you to them, but sadly those are both from Hackaday’s early years and link rot has taken their websites.

How To Avoid Getting Arc Flashed

September 3, 2026 by Maya Posch 48 Comments

After getting called out in the field to troubleshoot a large PV solar installation, [Derek] found himself suddenly in the midst of an arc flash, causing burns all over his face and arms. In a recent video he goes over the scenario that led up to this unfortunate event, as the holes in the Swiss cheese slowly lined themselves up, culminating in a high-current 480 VDC discharge nearly giving [Derek] a fatal embrace.

Despite being a professionally trained and certified professional, being called out to diagnose a weird issue on a slightly unusual solar farm’s electrical installation already worked against him. After having spent some time doing said troubleshooting, he finally tracked down the auxiliary transformer that normally powers the low-voltage gear, along with the spicy parts that should absolutely be unpowered after flipping the breaker into the ‘off’ position.

Testing for no power confirmed that the power had indeed been cut, which was when the wiring that normally connects the auxiliary transformer was spotted still lying just out of reach in the back of the cabinet. Clearly this was the cause behind one of the issues that the owner had been having.

This was when [Derek] decided to ~~go to the light~~ reach for this spool of wiring with a pair of pliers, into the – as it turned out – still live high-voltage side. One massive arc flash and hospital recovery later, [Derek] learned that the layout of the lines in the cabinet were different from usual, with the position of the roll of loose wiring being a potential hint that something was off.

The problem here was one of habituation, and the assumption that the system that he was working on was de-energized. The reason that he’s still with us being that the pliers acted as the current path instead of his body, and the arc flash cooked only the exposed parts of his skin, being mostly parts of his face and his hands.

Terrifyingly, [Derek] was working alone, and was forced to dial 911 somehow, with fingers that no longer registered on the iPhone’s touch screen on account of the skin having been turned into charcoal. While he doesn’t remember exactly how he managed to reach 911, it’s likely that the voice assistant finally connected him. The property owner also arrived and did what he could do to help before the ambulance arrived.

Overall, the lesson here is that complacency and assumptions are the killers here. Even if the layout of a high-voltage circuit is different in a way that makes no sense and there ought to be industry standards, when it’s you reaching into that cabinet such trivial details matter less than having ensured that there’s absolutely no power on anything, even if you know that there shouldn’t be. Reality only has to disagree with you once there.

[Derek] was lucky in the sense that the cabinet mostly shielded him from the arc flash’s intense heat, but over 19% of his skin was still burned, requiring skin grafts and an ongoing, very painful recovery. By sharing his story he hopes that he can prevent at least one other person reaching into that cabinet with some pliers for that ‘let me just quickly…’ moment.

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An arm and a hand: on the arm is a chunky blue box, and in the hand is a phone showing a dashboard.

HYDR8 Will Lead You To Water, But Will You Drink?

August 19, 2026 by Kristina Panos 16 Comments

[Ayushmaan] states up front that most of his free time is spent “building things that probably didn’t need to exist”. Well, this one might be an anomaly, because it seems pretty useful to us.

HYDR8, as it says on the tin, is a wearable that knows when it’s time to hydrate. The impetus for this one was something we all chase: the flow state. [Ayushmaan] would sit down, get deep into work, and look up hours later to to find that he had a headache and a full water bottle. Phone reminders were soon swiped away in annoyance.

This wearable is based on a XIAO ESP32-C3. It reads heart rate, oxygenation, skin temperature, and both the ambient temperature and humidity. It also learns your personal resting numbers range.

Taking all of this into consideration, it generates a heat/hydration stress score between 0-100. The thing is, HYDR8 tells you specifically what to do; sometimes it’s ‘drink water’ and other times, it’s ‘find shade’.

The wearable itself, while somewhat chunky, is pretty simple: it only shows the time and a message when it matters. The ESP32 hosts a full dashboard on your phone.

Keep in mind that this is not a medical device, it’s an experiment, a prototype. It can’t measure how hydrated you are. Instead, it measure hydration stress.

If you don’t want to wear anything, here’s a smart straw that uses a tiny turbine flowmeter and a Hall effect sensor to record the volume sipped, and detect whether the sipper is low on fluids. And if you find yourself under the hot lights of a wet bulb event, here’s how to survive it.

A desktop Borg cube. Just kidding, it's a buttonless, cube-shaped timer with a really neat 3D-printed enclosure.

FlipBuddy Is Borg, You Will Be Assimilated

August 7, 2026 by Kristina Panos 19 Comments

When you think about it, time is all we’ve really got. Where to go from there is ultimately up to you. Maybe you use an app to track every task, or just go with the onboard timer. But that can be a lot of steps to begin with, and then the phone screen goes dark again. For some people, the whole out of sight, out of mind thing will kick in. At worst, you get distracted, start doing something else, and then feel guilty and frustrated when the timer starts going off.

But there’s hope for us visual simpletons, and the purveyor of that hope is [Edris] of Ponderly Robotics. You see, [Edris] created an extremely easy-to-use timer that looks like something you’d find on Captain Picard’s desk as a token of defeating the Borg. But the affably-named FlipBuddy is far more useful than that description implies.

[Edris] uses the open-source FlipBuddy every day, and swears by its simplicity. The point is accessibility, and respect for privacy. That said, there’s a companion app to provide insight.

Basically, you assign a task to each cube face. Choose one, and place the cube with that side facing up. FlipBuddy wakes up, connects to WiFi, and then pushes your session to the cloud, bypassing the need for your phone.

Time to switch tasks? Just put the new side face up. When you’re done for the day, use the stop face, which we’re hoping means to set it on the knocked-off corner.

You don’t need much to make FlipBuddy come to life. [Edris] used an ESP32 (an S3 SuperMini or similar will work), an MPU6050, six WS2812B LEDs, and a 3.7 V Li-Po cell. The beautiful, 3D printed origami mesh enclosure prints as a single, flat piece, and you get to fold it up around the internals and make your new buddy come to life.

Part of the point of FlipBuddy is that it can become as intuitive as punching a chess clock. So if it’s buttons you’re after, check out this simple Pomodoro timer.

The Coolest Hat At The Hacker Camp

July 5, 2026 by Jenny List 27 Comments

People in hotter parts of the world may permit themselves a grin at this, but Europeans have recently been suffering under an unseasonal June heatwave. Most of us have been cowering inside with our air conditioners, but not [Making Stuff With Mike]. He’s adapting a safety helmet with a Noctua fan for only slightly uncool on-the-go cooling.

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Defeat Blood-Sucking Mosquitoes By Becoming The Bug Zapper

June 20, 2026 by Maya Posch 11 Comments

One of the stun gun modules with battery pack. (Credit: Dani Cruster DiWHY, YouTube)

Few things are more satisfying during a Summer night than hearing the crackle and pop of another mosquito hurling itself against a bug zapper and knowing that it won’t be trying to suck your blood any more. The only problem with those bug zappers, whether the mounted or hand-held type is that you cannot get every single attacking mosquito. Unless you were to put the bug zapper on yourself, of course. This is basically what [Dani Cruster] of the aptly named ‘DiWHY’ channel decided would be the right course of action.

The video is apparently dubbed over from the original Russian – with the team claimed to be based in Moldova – which probably explains a lot of the reasoning behind this engineering. At the core of the whole-body bug zapper is galvanized mesh, with a big question being how close you can get it to the body before said body gets zapped too. With about a millimeter of clearance between both layers of mesh required at 1 kV, this was another design consideration.

Ultimately the guts of stun guns were used, which output around 10 kV and thus require a 1 cm gap between the mesh layers. PVC plates were used to create the structural elements of the walking bug zapper suit, using a heatgun to form it into a body-appropriate shape. That’s when human testing started, to try and not make it zap the wearer.

The final suit of bug zapping armor uses six stun gun modules, each powered by a 3 V power source created from two 1.5 V alkaline cells that are good for an hour of zapping. One issue found during a human trial run was that the zip ties used turned out to actually cause arcing, which had to be addressed first before heading to the mosquito-infested woods. In the video these are said to be near Tarkov in what appears to be the national park in Russia’s Tver Oblast and clearly a prime mosquito breeding ground.

During the real-life test run many mosquitoes and apparently even some ticks find their electrifying demise, before for some reason they seem to clear out after an hour or so. Overall it seems to work well, even if it’s not that ergonomic and things get spicy when it starts to rain.

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Building A Ceiling-Based Crane Robot To Keep A Room Clean

June 15, 2026 by Maya Posch 28 Comments

One of the joys you get to experience whether as a proud parent or pet owner is that a lot of things get left around haphazardly. You could of course pick every piece of discarded clothing, half-destroyed toy and detritus yourself, but as a parent of three children himself [Nathaniel Nifong] opted to use his engineering background to potentially over engineer a wires-suspended robotic claw to do this picking up for him.

What he calls Stringman robots requires an anchoring point at four corners of a room, after which the robotic crane can then scour across the ceiling, identify targets to pick up and move these to predesignated drop-off points. It’s an open source project with the LeRobot-based firmware available on GitHub in addition to build instructions for the physical hardware. There’s also a pilot run of ready to use hardware and kits for those who want to trial it, but aren’t interested in building it themselves via [Nathaniel]’s company website.

The basic idea is that this crane can run for an hour or so and deal with the mess in its room without having to do anything yourself. The process isn’t perfect yet, of course, with the underlying diffusion transformer to implement machine vision requiring more refinement. The gripper itself struggles with objects like books, which can be a concern for parents and bookworms, and of course while the crane is operating the wires will dip down as a potential risk to anyone in the room.

Compared to an overhead crane like a traditional bridge crane this wire-suspension crane is probably more stable, but either is an interesting engineering challenge when applied to a household. Next it would probably also be cool if items could be put away where they belong instead of dropped into a bin, as so far that task will still be left to deal with by the adult humans.

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