Flashlight shining through gold leaf on glass

Shining Through: Germanium And Gold Leaf Transparency

Germanium. It might sound like just another periodic table entry (number 32, to be exact), but in the world of infrared light, it’s anything but ordinary. A recent video by [The Action Lab] dives into the fascinating property of germanium being transparent to infrared light. This might sound like sci-fi jargon, but it’s a real phenomenon that can be easily demonstrated with nothing more than a flashlight and a germanium coin. If you want to see how that looks, watch the video on how it’s done.

The fun doesn’t stop at germanium. In experiments, thin layers of gold—yes, the real deal—allowed visible light to shine through, provided the metal was reduced to a thickness of 100 nanometers (or: gold leaf). These hacks reveal something incredible: light interacts with materials in ways we don’t normally observe.

For instance, infrared light, with its lower energy, can pass through germanium, while visible light cannot. And while solid gold might seem impenetrable, its ultra-thin form becomes translucent, demonstrating the delicate dance of electromagnetic waves and electrons.

The implications of these discoveries aren’t just academic. From infrared cameras to optics used in space exploration, understanding these interactions has unlocked breakthroughs in technology. Has this article inspired you to craft something new? Or have you explored an effect similar to this? Let us know in the comments!

We usually take our germanium in the form of a diode. Or, maybe, a transistor.

Continue reading “Shining Through: Germanium And Gold Leaf Transparency”

Nottingham Railway departure board in Hackspace

All Aboard The Hack Train: Nottingham’s LED Revival

Hackerspaces are no strangers to repurposing outdated tech, and Nottingham Hackspace happens to own one of those oddities one rarely gets their hands on: a railway departure board. Left idle for over a decade, it was brought back to life by [asjackson]. Originally salvaged around 2012, it remained unused until mid-2024, when [asjackson] decided to reverse-engineer it. The board now cycles between displaying Discord messages and actual train departures from Nottingham Railway Station every few minutes. The full build story can be found in this blog post.

The technical nitty-gritty is fascinating. Each side of the board contains 4,480 LEDs driven as two parallel chains. [asjackson] dove into its guts, decoding circuits, fixing misaligned logic levels, and designing custom circuit boards in KiCAD. The latest version swaps WiFi for a WizNet W5500 ethernet module and even integrates the Arduino Uno R4 directly into the board’s design. Beyond cool tech, the display connects to MQTT, pulling real-time train data and Discord messages via scripts that bridge APIs and custom Arduino code.

This board is a true gem for any hackerspace, even more so now it’s working. It waited for the exact mix of ingredients why hackerspaces exist in the first place: curiosity, persistence, and problem-solving. Nottingham Hackspace is home to a lot more, as we once wrote in this introductory article.If you don’t have room for the real thing, maybe set your sights a bit smaller.

Do you have a statement piece this cool in your hackerspace or your home? Tip us!

Continue reading “All Aboard The Hack Train: Nottingham’s LED Revival”

Close up of a Hornet Nest circuit board

PoE-Power Protection: The Hornet Nest Alarm Panel

Have you ever thought of giving new buzz to outdated wired alarm systems or saving money while upgrading your home security? The Hornet Nest Alarm Panel, to which hacker [Patrick van Oosterwijck] contributes, does just that. Designed for domotics enthusiasts, it offers 42 sensor zones and seamless integration with Home Assistant and ESPHome. This open-source gem uses the wESP32 board, which combines an ESP32 with Ethernet and Power over Ethernet (PoE) for robust, reliable connectivity. Check out the Crowd Supply campaign for details.

So what makes this Hornet Nest special? Besides its hackable nature, it repurposes existing wired sensors, reducing waste and cost. Unlike WiFi-dependent solutions, the PoE-powered ESP32 ensures stable performance, even in hard-to-reach locations. The optional USB programming port is genius—it’s there when you need it but doesn’t clutter the board when you don’t. With its isolated circuits, long-cable safety, and smart Ethernet, WiFi, and Bluetooth combination, this system ticks every DIY box.

Hackaday has featured other DIY PoE-powered projects, offering more inspiration for smart automation enthusiasts.

Continue reading “PoE-Power Protection: The Hornet Nest Alarm Panel”

Puzzle Bobble on a screen with a physical gadget in front

Crafting A Cardboard Tribute To Puzzle Bobble

What do you get when you cross cardboard, deodorant rollers, and a love for retro gaming? A marvel of DIY engineering that brings the arcade classic Puzzle Bobble to life—once again! Do you remember the original Puzzle Bobble aiming mechanism we featured 12 years ago? Now, creator [TomTilly] has returned with a revamped version, blending ingenuity with a touch of nostalgia. [Tom] truly is a Puzzle Bobble enthusiast. And who could argue that? The game’s simplicty makes for innocent yet addictive gameplay.

[Tom]’s new setup recreates Puzzle Bobble’s signature aiming mechanic using surprising materials: deodorant roller balls filled with hot glue (to diffuse LED colours), bamboo skewers, and rubber bands. At its heart is an Arduino UNO, which syncs the RGB LED ‘bubbles’ and a servo-driven aiming arm to the game’s real-time data. A Lua script monitors MAME’s memory locations to match the bubble colours and aimer position.

But this isn’t just a static display. [Tom] hints at a version 2.0: a fully functional controller complete with a handle. Imagine steering this tactile masterpiece through Puzzle Bobble’s frantic levels!

Need more inspiration? Check out other quirky hacks like [Tom]’s deodorant roller controller we featured in 2023. Whether you’re into cardboard mechanics or retro gaming, there’s no end to what clever hands can create.

Continue reading “Crafting A Cardboard Tribute To Puzzle Bobble”

Bokeh photo of red light particles in the dark

Beam Me Up: Simple Free-Space Optical Communication

Let’s think of the last time you sent data without wires. We’re not talking WiFi here, but plain optical signals. Free-space optical communication, or FSO, is an interesting and easy way to transmit signals through light beams. Forget expensive lasers or commercial-grade equipment; this video by [W1VLF] offers a simple and cheap entry point for anyone with a curiosity for DIY tech. Inspired by a video on weak signal sources for optical experiments, this project uses everyday components like a TV remote-control infrared LED and a photo diode. The goal is simply to establish optical communication across distances for under $10. Continue reading “Beam Me Up: Simple Free-Space Optical Communication”

close up hands holding lighting pcb

Circuit Secrets: Exploring A $5 Emergency Light

Who would’ve thought a cheap AliExpress emergency light could be packed with such crafty design choices? Found for about $5, this unit uses simple components yet achieves surprisingly sophisticated behaviors. Its self-latching feature and decisive illumination shut-off are just the beginning. A detailed analysis by [BigCliveDotCom] reveals a smart circuit that defies its humble price.

The circuit operates via a capacitive dropper, a cost-effective way to power low-current devices. What stands out, though, is its self-latching behavior. During a power failure, transistors manage to keep the LEDs illuminated until the battery voltage drops below a precise threshold, avoiding the dreaded fade-to-black. Equally clever is the automatic shut-off when the voltage dips too low, sparing the battery from a full drain.

Modifications are possible, too. For regions with 220V+ mains, swapping the dropper capacitor with a 470nF one can reduce heat dissipation. Replacing the discharge resistor (220k) with a higher value improves longevity by running cooler. What remarkable reverse engineering marvels have you come across? Share it in the comments!  After all, it is fun to hack into consumer stuff. Even if it is just a software hack.

Continue reading “Circuit Secrets: Exploring A $5 Emergency Light”

desk with a hand holding a Lego unit

LDU Decoded: The Untold Tale Of LEGO Dimensions

LEGO bricks might look simplistic, but did you know there’s an actual science behind their sizes? Enter LDUs — LEGO Draw Units — the minuscule measurement standard that allows those tiny interlocking pieces to fit together seamlessly. In a recent video [Brick Sculpt] breaks down this fascinating topic.

So, what is an LDU precisely? It’s the smallest incremental size used to define LEGO’s dimensions. For context, a standard LEGO brick is 20 LDUs wide, and a single plate is 8 LDUs tall. Intriguingly, through clever combinations of headlight bricks, jumper plates, and even rare Minifig neck brackets, builders can achieve offsets as tiny as 1 LDU! That’s the secret sauce behind those impossibly detailed LEGO creations.

We already knew that LEGO is far more than a toy, but this solidifies that theory. It’s a means of constructing for anyone with an open mind – on its own scale. The video below explains in detail how to achieve every dimension possible. If that inspires you to build anything, dive into these articles and see if you can build upon this discovery!

Continue reading “LDU Decoded: The Untold Tale Of LEGO Dimensions”