Getting a robot to stand on two wheels without tipping over involves a challenging dance with the laws of physics. Self-balancing robots are a great way to get into control systems, sensor fusion, and embedded programming. This build by [mircemk] shows how to make one with just a few common components, an Arduino, and a bit of patience fine-tuning the PID controller.

At the heart of the bot is the MPU6050 – a combo accelerometer/gyroscope sensor that keeps track of tilt and movement. An Arduino Uno takes this data, runs it through a PID loop, and commands an L298N motor driver to adjust the speed and direction of two DC motors. The power comes from two Li-ion batteries feeding everything with enough juice to keep it upright. The rest of the magic lies in the tuning.

PID (Proportional-Integral-Derivative) control is what makes the robot stay balanced. Kp (proportional gain) determines how aggressively the motors respond to tilting. Kd (derivative gain) dampens oscillations, and Ki (integral gain) helps correct slow drifts. Set them wrong, and your bot either wobbles like a confused penguin or falls flat on its face. A good trick is to start with only Kp, then slowly add Kd and Ki until it stabilizes. Then don’t forget to calibrate your MPU6050; each sensor has unique offsets that need to be compensated in the code.

Once dialed in, the result is a robot that looks like it defies gravity. Whether you’re hacking it for fun, turning it into a segway-like ride, or using it as a learning tool, a balancing bot is a great way to sharpen your control system skills. For more inspiration, check out this earlier attempt from 2022, or these self-balancing robots (one with a little work) from a year before that. You can read up on [mircemk]’s project details here.

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.

Original photo by Kelly Sikkema on Unsplash

For those who love systems and structure, owning a 19-inch rack with just one slot filled is just not it. But what if the rest of your gear isn’t 19-inch? Well, then you go out and make it so, just like [Cal Bryant] did recently.

The goal was to consolidate multiple devices — DAC, input selector, streamer, and power routing — into a single 2U rackmount unit. His first attempts involved drilling 1U panels to attach gear with removable faceplates. That worked, but not all devices played nice. So his next step became a fully custom enclosure with CAD-modeled brackets and front panels.

OpenSCAD turned out to be a lifesaver, letting [Cal] design modular mounting solutions. Exporting proper circles for CNC turret punching however appeared to be a nightmare. It was FreeCAD to the rescue for post-processing. After some sanding and auto-shop painting, the final faceplate looked factory-made.

Custom switch boxes for power and audio routing keep things tidy, housing everything from USB to XLR inputs. A 4-pole switch even allows seamless swapping between his DAC and DJ controller, while UV-printed graphics bring the finishing touch to this project. For those looking to clean up their Hi-Fi setup (or just love modding for the sake of it), there’s a lot to learn from this build.

If buying a rack is not within your budget, you could start with well-known IKEA LACK furniture.

Shortwave radio has a charm all its own: part history, part mystery, and a whole lot of tech nostalgia. The Hallicrafters S-53A is a prime example of mid-century engineering, but when you get your hands on one, chances are it won’t be in mint condition. Which was exactly the case for this restoration project by [Ken’s Lab], where the biggest challenge wasn’t fried capacitors or burned-out tubes, but a stubborn band selector switch that refused to budge.

What made it come to this point? The answer is: time, oxidation, and old-school metal tolerances. Instead of forcing it (and risking a very bad day), [Ken]’s repair involved careful disassembly, a strategic application of lubricant, and a bit of patience. As the switch started to free up, another pleasant surprise emerged: all the tubes were original Hallicrafters stock. A rare find, and a solid reason to get this radio working without unnecessary modifications. Because some day, owning a shortwave radio could be a good decision.

Once powered up, the receiver sprang to life, picking up shortwave stations loud and clear. Hallicrafters’ legendary durability proved itself once before, in this fix that we covered last year. It’s a reminder that sometimes, the best repairs aren’t about drastic changes, but small, well-placed fixes.

What golden oldie did you manage to fix up?

What do you do when you need to choose an OS at boot but aren’t physically near your machine? [Dakhnod]’s inventive solution is a mix of GRUB, Wake-on-LAN (WOL), and a lightweight ESP8266 running a simple HTTP server. In the past, [dakhnod] already enlightened us with another smart ESP hack. This one’s a clever combination of network booting and remote control that opens up possibilities beyond the usual dual-boot selector.

At its core, the hack modifies GRUB to fetch its boot configuration over HTTP. The ESP8266 (or any low-power device) serves up a config file defining which OS should launch. The trick lies in adding a custom script that tells GRUB to source an external config:

#!/usr/bin/env cat 
net_dhcp 
source (http,destination_ip_or_host:destination_port)/grub/config

Since GRUB itself makes the HTTP request, the system needs a running web server. That could be a Raspberry Pi, another machine, or the ESP itself. From there, a WOL-enabled ESP button can wake the PC and set the boot parameters remotely.

Is it secure? Well, that depends on your network. An open, unauthenticated web server dishing out GRUB configs is risky, but within a controlled LAN or a VLAN-segmented environment, it’s an intriguing option. Automation possibilities are everywhere — imagine remotely booting test rigs, toggling between OS environments for debugging, or even setting up kiosk machines that reconfigure themselves based on external triggers.

For those looking to take it further, using configfile instead of source allows for more dynamic menu entries, although it won’t persist environment variables. You could even combine it with this RasPi hack to control the uptime of the HTTP server. The balance between convenience and security is yours to strike.

If you’ve got your own wild GRUB customisation, let’s hear it!

If you’re into Soviet-era gear with a techy twist, you’ll love this teardown of a rare Zenit 19 camera courtesy of [msylvain59]. Found broken on eBay (for a steal!), this 1982 made-in-USSR single-lens reflex camera isn’t the average Zenit. It features, for example, electronically controlled shutter timing – quite the upgrade from its manual siblings.

The not-so-minor issue that made this Zenit 19 come for cheap was a missing shutter blade. You’d say – one blade gone rogue! Is it lost in the camera’s guts, or snapped clean off? Add to that some oxidized battery contacts and a cracked viewfinder, and you’ve got proper fixer-upper material. But that’s where it gets intriguing: the camera houses a rare hybrid electronic module (PAPO 074), complete with epoxy-covered resistors. The shutter speed dial directly adjusts a set of resistors, sending precise signals to the shutter assembly: a neat blend of old-school mechanics and early electronics.

Now will it shutter, or stutter? With its vertical metal shutter – uncommon in Zenits – and separate light metering circuitry, this teardown offers a rare glimpse into Soviet engineering flair. Hungry for more? We’ve covered a Soviet-era computer and a radio in the past. If you’re more into analog camera teardowns, you might like this analog Pi upgrade attempt, or this bare minimum analog camera project.

Did you know that the land of flat-pack furniture and Saab automobiles played a serious role in the development of minicomputers, the forerunners of our home computers? If not, read on for a bit of history. You can also go ahead and watch the video below, which tells it all with a ton of dug up visuals.

Sweden’s early computer development was marked by significant milestones, beginning with the relay-based Binär Aritmetisk Relä-Kalkylator (BARK) in 1950, followed by the vacuum tube-based Binär Elektronisk SekvensKalkylator (BESK) in 1953. These projects were spearheaded by the Swedish Board for Computing Machinery (Matematikmaskinnämnden), established in 1948 to advance the nation’s computing capabilities.

In 1954, Saab ventured into computing by obtaining a license to replicate BESK, resulting in the creation of Saab’s räkneautomat (SARA). This initiative aimed to support complex calculations for the Saab 37 Viggen jet fighter. Building on this foundation, Saab’s computer division, later known as Datasaab, developed the D2 in 1960 – a transistorized prototype intended for aircraft navigation. The D2’s success led to the CK37 navigational computer, which was integrated into the Viggen aircraft in 1971.

Datasaab also expanded into the commercial sector with the D21 in 1962, producing approximately 30 units for various international clients. Subsequent models, including the D22, D220, D23, D5, D15, and D16, were developed to meet diverse computing needs. In 1971, Datasaab’s technologies merged with Standard Radio & Telefon AB (SRT) to form Stansaab AS, focusing on real-time data systems for commercial and aviation applications. This entity eventually evolved into Datasaab AB in 1978, which was later acquired by Ericsson in 1981, becoming part of Ericsson Information Systems.

Parallel to these developments, Åtvidabergs Industrier AB (later Facit) produced the FACIT EDB in 1957, based on BESK’s design. This marked Sweden’s first fully domestically produced computer, with improvements such as expanded magnetic-core memory and advanced magnetic tape storage. The FACIT EDB was utilized for various applications, including meteorological calculations and other scientific computations. For a short time, Saab even partnered with the American Unisys called Saab-Univac – a well-known name in computer history.

These pioneering efforts by Swedish organizations laid the groundwork for the country’s advancements in computing technology, influencing both military and commercial sectors. The video below has lots and lots more to unpack and goes into greater detail on collaborations and (missed) deals with great names in history.

If you think shorting a transformer’s winding means big sparks and fried wires: think again. In this educational video, titled The Magnetic Bypass, [Sam Ben-Yaakov] flips this assumption. By cleverly tweaking a reluctance-based magnetic circuit, this hack channels flux in a way that breaks the usual rules. Using a simple free leg and a switched winding, the setup ensures that shorting the output doesn’t spike the current. For anyone who is obsessed with magnetic circuits or who just loves unexpected engineering quirks, this one is worth a closer look.

So, what’s going on under the hood? The trick lies in flux redistribution. In a typical transformer, shorting an auxiliary winding invites a surge of current. Here, most of the flux detours through a lower-reluctance path: the magnetic bypass. This reduces flux in the auxiliary leg, leaving voltage and current surprisingly low. [Sam]’s simulations in LTspice back it up: 10 V in yields a modest 6 mV out when shorted. It’s like telling flux where to go, but without complex electronics. It is a potential stepping stone for safer high-voltage applications, thanks to its inherent current-limiting nature.

The original video walks through the theory, circuit equivalences, and LTspice tests. Enjoy!

In a recent video, [Shahriar] from The Signal Path has unveiled the intricate design and architecture of optical HDMI cables, offering a cost-effective solution to extend HDMI 2.0 connections beyond the limitations of traditional copper links. This exploration is particularly captivating for those passionate about innovative hardware hacks and signal transmission technologies.

[Shahriar] begins by dissecting the fundamentals of HDMI high-speed data transmission, focusing on the Transition Minimized Differential Signaling (TMDS) standard. He then transitions to the challenges of converting from twisted-pair copper to optical lanes, emphasizing the pivotal roles of Vertical-Cavity Surface-Emitting Lasers (VCSELs) and PIN photodiodes. These components are essential for transforming electrical signals into optical ones and vice versa, enabling data transmission over greater distances without significant signal degradation.

A standout aspect of this teardown is the detailed examination of the optical modules, highlighting the use of free-space optics and optical confinement techniques with lasers and detectors. [Shahriar] captures the eye diagram of the received high-speed lane and confirms the VCSELs’ optical wavelength at 850 nm. Additionally, he provides a microscopic inspection of the TX and RX chips, revealing the intricate VCSEL and photodetector arrays. His thorough analysis offers invaluable insights into the electronic architecture of optical HDMI cables, shedding light on the complexities of signal integrity and the innovative solutions employed to overcome them.

For enthusiasts eager to take a deeper look into the nuances of optical HDMI technology, [Shahriar]’s comprehensive teardown serves as an excellent resource. It not only gives an insight in the components and design choices involved, but also inspires further exploration into enhancing data transmission methods.

In the near future, imagine a world where your health is continuously monitored, not through bulky devices but through an invisible graphene tattoo. Developed at the University of Massachusetts Amherst, these tattoos could soon detect a range of health metrics, including blood pressure, stress levels, and even biomarkers of diseases like diabetes. This technology, though still in its infancy, promises to revolutionize how we monitor health, making it possible to track our bodies’ responses to everything from exercise to environmental exposure in real-time.

Graphene, a single layer of carbon atoms, is key to the development of these tattoos. They are flexible, transparent, and conductive, making them ideal for bioelectronics. The tattoos are so thin and pliable that users won’t even feel them on their skin. In early tests, graphene electronic tattoos (GETs) have been used to measure bioimpedance, which correlates with blood pressure and other vital signs. The real breakthrough here, however, is the continuous, non-invasive monitoring that could enable early detection of conditions that usually go unnoticed until it’s too late.

While still requiring refinement, this technology is advancing rapidly. Graphene still amazes us, but it’s no longer just science fiction. Soon, these tattoos could be a part of everyday life, helping individuals track their health and enabling better preventative care. Since we’re hackers out here –  but this is a far fetch – combining this knowledge on graphene production, and this article on tattooing with a 3D printer, could get you on track. Let us know, what would you use graphene biosensors for?

Original photo by engin akyurt on Unsplash

Virtual Reality in woodworking sounds like a recipe for disaster—or at least a few missing fingers. But [The Swedish Maker] decided to put this concept to the test, diving into a full woodworking project while wearing a Meta Quest 3. You can check out the full experiment here, but let’s break down the highs, lows, and slightly terrifying moments of this unconventional build.

The plan: complete a full furniture build while using the VR headset for everything—from sketching ideas to cutting plywood. The Meta Quest 3’s passthrough mode provided a semi-transparent AR view, allowing [The Swedish Maker] to see real-world tools while overlaying digital plans. Sounds futuristic, right? Well, the reality was more like a VR fever dream. Depth perception was off, measuring was a struggle, and working through a screen-delayed headset was nauseating at best. Yet, despite the warped visuals, the experiment uncovered some surprising advantages—like the ability to overlay PDFs in real-time without constantly running back to a computer.

So is VR useful to the future of woodworking? If you’re a woodworking novice, you might steer clear from VR and read up on the basics first. For the more seasoned: maybe, when headsets evolve beyond their current limitations. For now, it’s a hilarious, slightly terrifying experiment that might just inspire the next wave of augmented reality workshops. If you’re more into electronics, we did cover the possibilities with AR some time ago. We’re curious to know your thoughts on this development in the comments!

Building a robotic arm and hand that matches human dexterity is tougher than it looks. We can create aesthetically pleasing ones, very functional ones, but the perfect mix of both? Still a work in progress. Just ask [Sarah de Lagarde], who in 2022 literally lost an arm and a leg in a life-changing accident. In this BBC interview, she shares her experiences openly – highlighting both the promise and the limits of today’s prosthetics.

The problem is that our hands aren’t just grabby bits. They’re intricate systems of nerves, tendons, and ridiculously precise motor control. Even the best AI-powered prosthetics rely on crude muscle signals, while dexterous robots struggle with the simplest things — like tying shoelaces or flipping a pancake without launching it into orbit.

That doesn’t mean progress isn’t happening. Researchers are training robotic fingers with real-world data, moving from ‘oops’ to actual precision. Embodied AI, i.e. machines that learn by physically interacting with their environment, is bridging the gap. Soft robotics with AI-driven feedback loops mimic how our fingers instinctively adjust grip pressure. If haptics are your point of interest, we have posted about it before.

The future isn’t just robots copying our movements, it’s about them understanding touch. Instead of machine learning, we might want to shift focus to human learning. If AI cracks that, we’re one step closer.

Original photo by Marco Bianchetti on Unsplash

The days that PDFs were the granny-proof Swiss Army knives of document sharing are definitely over, according to [vk6]. He has managed to pull off the ultimate mind-bender: running Linux inside a PDF file. Yep, you read that right. A full Linux distro chugging along in a virtual machine all encapsulated within a document. Just when you thought running DOOM was the epitome of it. You can even try it out in your own browser, right here. Mind-boggling, or downright Pandora’s box?

Let’s unpack how this black magic works. The humble PDF file format supports JavaScript – with a limited standard library, mind you. By leveraging this, [vk6] managed to compile a RISC-V emulator (TinyEMU) into JavaScript using an old version of Emscripten targeting asm.js instead of WebAssembly. The emulator, embedded within the PDF, interfaces with virtual input through a keyboard and text box.

The graphical output is ingeniously rendered as ASCII characters – each line displayed in a separate text field. It’s a wild solution but works astonishingly well for something so unconventional.

Security-wise, this definitely raises eyebrows. PDFs have long been vectors for malware, but this pushes things further: PDFs with computational power. We know not to trust Word documents, whether they just capable of running Doom, or trash your entire system in a blink. This PDF anomaly unfolds a complete, powerful operating system in front of your very eyes. Should we think lightly, and hope it’ll lead to smarter, more interactive PDFs – or will it bring us innocent looking files weaponized for chaos?

Curious minds, go take a look for yourself. The project’s code is available on GitHub.

When you see a ventriloquist like [Jeff Dunham], you probably expect to see him with a puppet. This time – spoilers ahead – you won’t. Besides his fame on stage, [Dunham] is also a collector of vintage tech and a die-hard television enthusiast. In the video below, [Dunham] has gotten his hands on a rarity: an unboxed 1958 Philco Predicta TV. The original tape was still on the box. We get to follow along on his adventure to restore this sleek, retro-futuristic relic!

[Dunham]’s fascination with the Predicta stems from its historical significance and bold design. At a time when television was making its way into American homes, the Predicta dared to be different with its swivel-mounted picture tube and early printed circuit boards. Despite its brave aesthetics, the Predicta’s ambition led to notorious reliability issues. Yet, finding one in pristine condition, sealed and untouched for over six decades, is like unearthing a technological time capsule.

What makes this story unique is [Dunham]’s connection to both broadcasting and his craft. As a ventriloquist inspired by Edgar Bergen — whose radio shows captivated America — [Dunham] delights in restoring a TV from the same brand that first brought his idol’s voice to airwaves. His love for storytelling seamlessly translates into this restoration adventure.

After unboxing, [Dunham’s] team faces several challenges: navigating fragile components, securing the original shipping brace, and cautiously ramping up voltage to breathe life into the Predicta. The suspense peaks in the satisfying crackle of static, and the flicker of a 65-year-old screen finally awakened from slumber.

Have you ever come across an opportunity like this? Tell us about your favorite new old stock find in the comments. Buying these can be a risk, since components have a shelf life. We appreciate when these old TVs play period-appropriate shows. Who wants to watch Game of Thrones on a Predicta?

Ever stopped at a red light and noticed something odd about the poles holding up the traffic lights? Look closer next time—many of them appear to hover just above the concrete, anchored by visible bolts. This video below explains it all. It’s not a job left unfinished. It is actually clever design, and all about functionality and easy maintenance. Let’s break down why engineers prefer this so-called ‘floating’ base plate setup.

At first, you might think mounting poles directly into concrete would be more stable—after all, that’s how heavy columns are often installed. But traffic light poles are lightweight, hollow, and face constant wind pressure. Instead of brute stability, they need flexibility and precise alignment. Enter the standoff base plate. By resting on leveling nuts, these poles can be fine-tuned for perfect verticality, even when the ground shifts slightly over time. That’s critical for keeping your 30-foot pole from leaning like the Tower of Pisa.

The open design also simplifies maintenance. If the pole tilts after years of wear, it takes just a few nut adjustments to fix it—no heavy cranes required. Plus, the gap helps prevent moisture buildup, reducing corrosion. So next time you’re waiting at an intersection, you’ll know it’s not just clever engineering—it’s practical street smarts. If you’re an infrastructure nut, this slightly older article might spark your interest.

This unusual tattoo hack by [Emily The Engineer] is not for the weak of heart, but let’s be frank: we kind of know her for that. And she gives out a warning, albeit at a good 10 minutes in, to not do this at home. What she’s about to do takes creativity and tech obsession to the next level: to transform a 3D printer into a functional tattoo machine. Therefore, [Emily] ingeniously modified one of her standard 3D printers to operate two-dimensionally, swapped its plastic extruder for a tattoo gun, and, yes, even managed to persuade a willing participant to try it out.

The entire process can be seen in [Emily]’s video below, which humorously yet meticulously documents the journey from Sharpie test runs to actually inking skin. Aside from a lot of tongue-in-cheek trial and error, this project requires a sheer amount of problem-solving. [Emily] employs firmware edits to bypass safety checks, and clever hardware adaptations to ensure smooth transitions between strokes. One impressive upgrade is the emergency solenoid system, a literal panic button to stop the machine mid-tattoo in case of trouble—a critical addition for something with needles involved!

This hack sits on the edge of DIY body modification, raising eyebrows and technical questions alike. If you missed the warning and are now frantically searching for tattoo removal options, know we’ve covered some (but you might be rightfully scared of automating that, too, at this point). If you haven’t lifted a finger while reading this, just do the safe thing: watch [Emily]’s video, and tinker about the subsequent purposes this discovery creates for 3D printing or tattoo art.