A cuboctahedron (a kind of polyhedron) made out of LED filaments is being held above a man's hand in front a computer screen.

The Graph Theory Of Circuit Sculptures

February 3, 2026 by Aaron Beckendorf 6 Comments

Like many of us, [Tim]’s seen online videos of circuit sculptures containing illuminated LED filaments. Unlike most of us, however, he went a step further by using graph theory to design glowing structures made entirely of filaments.

The problem isn’t as straightforward as it might first appear: all the segments need to be illuminated, there should be as few powered junctions as possible, and to allow a single power supply voltage, all paths between powered junctions should have the same length. Ideally, all filaments would carry the same amount of current, but even if they don’t, the difference in brightness isn’t always noticeable. [Tim] found three ways to power these structures: direct current between fixed points, current supplied between alternating points so as to take different paths through the structure, and alternating current supplied between two fixed points (essentially, a glowing full-bridge rectifier).

To find workable structures, [Tim] represented circuits as directed graphs, with each junction being a vertex and each filament a directed edge, then developed filter criteria to find graphs corresponding to working circuits. In the case of power supplied from fixed points, the problem turned out to be equivalent to the edge-geodesic cover problem. Graphs that solve this problem are bipartite, which provided an effective filter criterion. The solutions this method found often had uneven brightness, so he also screened for circuits that could be decomposed into a set of paths that visit each edge exactly once – ensuring that each filament would receive the same current. He also found a set of conditions to identify circuits using rectifier-type alternating current driving, which you can see on the webpage he created to visualize the different possible structures.

We’ve seen some artistic illuminated circuit art before, some using LED filaments. This project doesn’t take exactly the same approach, but if you’re interested in more about graph theory and route planning, check out this article.

LED Interior Lighting Could Compromise Human Visual Performance

February 3, 2026 by Lewin Day 66 Comments

LED lighting is now commonplace across homes, businesses, and industrial settings. It uses little energy and provides a great deal of light. However, a new study suggests it may come with a trade-off. New research suggests human vision may not perform at its peak under this particular form of illumination.

The study ran with a small number of subjects (n=22) aged between 23 to 65 years. They were tested prior to the study for normal visual function and good health. Participants worked exclusively under LED lighting, with a select group then later also given supplemental incandescent light (with all its attendant extra wavelengths) in their working area—which appears to have been a typical workshop environment.

*Incandescent bulbs have a much broader spectrum of output than even the best LEDs. Credit: Research paper*

Notably, once incandescent lighting was introduced, those experimental subjects showed significant increases in visual performance using ChromaTest color contrast testing. This was noted across both tritan (blue) and protan (red) axes of the test, which involves picking out characters against a noisy background. Interestingly, the positive effect of the incandescent lighting did not immediately diminish when those individuals returned to using purely LED lighting once again. At tests 4 and 6 weeks after the incandescent lighting was removed, the individuals continued to score higher on the color contrast tests. Similar long-lasting effects have been noted in other studies involving supplementing LED lights with infrared wavelengths, however the boost has only lasted for around 5 days.

The exact mechanism at play here is unknown. The study authors speculate as to a range of complex physical and biological mechanisms that could be at play, but more research will be needed to tease out exactly what’s going on. In any case, it suggests there may be a very real positive effect on vision from the wider range of wavelengths provided by good old incandescent bulbs. As an aside, if you’ve figured out how to get 40/40 vision with a few cheap WS2812Bs, don’t hesitate to notify the tip line.

Thanks to [Keith Olson] for the tip!

Solar Supercapacitor Lamp Probably Won’t Get You Saved At Sea

January 29, 2026 by Lewin Day 19 Comments

Most solar lights are cheap garbage that exist just to put more microplastics into the environment as they degrade in short order. [Jeremy Cook] built his own solar light, however, and this one might just last a little longer.

Most solar lights rely on the cheapest nickel-cadmium or nickel-metal hydride cells that are available on the market. They don’t tend to have a lot of capacity and they wear out incredibly fast. [Jeremy] went a different route for his build, though, instead relying on a rather tasty supercapacitor to store energy. Unlike a rechargeable battery, that may only last a few thousand cycles, these supercaps are expected to perform over 500,000 charge/discharge cycles without failure. With such longevity, [Jeremy] suggests his build could last a full 1369.8 years, assuming it charged and discharged once a day. Whether the plastic transistor, LEDs, or diode could hold up over such a long period is another question entirely.

Electronically, the build is relatively simple. The solar panel collects light energy and turns it into electricity, charging the supercaps through a diode. The supercaps are only able to discharge through a transistor, which only turns on when the voltage output by the solar panel drops at night time, and the voltage on the base becomes lower than that on the emitter. When current flows through the transistor, it then lights the LED in turn and the device glows in the darkness. As a nice touch, the whole circuit is installed in a glass jug of syrup originally sourced from Costco. Files are on Github for those eager to explore further.

Given the light-in-a-bottle construction, [Jeremy] also playfully imagined that a lamp like this could theoretically be used as a safety device. If lost at sea, you could charge it using the sun and try and use it to signal for help. However, upon casually exploring the concept, he notes that a small solar-powered light will only raise the chance of a far-off ocean rescue from “extremely unlikely” to “still very unlikely.”

You can do all kinds of neat things with free energy from the sun, from mowing your lawn to processing waste products. Video after the break.

Continue reading “Solar Supercapacitor Lamp Probably Won’t Get You Saved At Sea” →

Building A Light That Reacts To Radio Waves

January 29, 2026 by Lewin Day 12 Comments

When it comes to electromagnetic waves, humans can really only directly perceive a very small part of the overall spectrum, which we call “visible light.” [rootkid] recently built an art piece that has perception far outside this range, turning invisible waves into a visible light sculpture.

The core of the device is the HackRF One. It’s a software defined radio (SDR) which can tune signals over a wide range, from 10 MHz all the way up to 6 GHz. [rootkid] decided to use the HackRF to listen in on transmissions on the 2.4 GHz and 5 GHz bands. This frequency range was chosen as this is where a lot of devices in the home tend to communicate—whether over WiFi, Bluetooth, or various other short-range radio standards.

The SDR is hooked up to a Raspberry Pi Zero, which is responsible for parsing the radio data and using it to drive the light show. As for the lights themselves, they consist of 64 filament LEDs bent into U-shapes over a custom machined metal backing plate. They’re controlled over I2C with custom driver PCBs designed by [rootkid]. The result is something that looks like a prop from some high-budget Hollywood sci-fi. It looks even better when the radio waves are popping and the lights are in action.

It’s easy to forget about the rich soup of radio waves that we swim through every day.

Continue reading “Building A Light That Reacts To Radio Waves” →

Fiber Optic Lamp Modified To Be Scarily Bright

January 21, 2026 by Lewin Day 21 Comments

[Brainiac75] is a fan of fiber optic lamps, except for one thing—they’re often remarkably dim. Thus, they set out to hack the technology to deliver terrifying amounts of light while still retaining their quirky charm.

Older fiber optic lamps use a dim filament lamp or halogen lamp to light them up. They also often feature a spinning color disk to vary the light patterns, which does have the side effect of absorbing some of the already-limited light output.

When it came to upgrading his own decades-old lamp, [Braniac75] decided to initially stick within the specs of the original halogen lamp. The fixture was rated for 12 volts at 5 watts, with a GU4/GZ4 compatible base, and white light was desired so the color wheel could still do its thing. Swapping out the original 5 W halogen for a 2.5 W LED unit brought a big upgrade in brightness, since the latter is roughly equivalent to a 20 W halogen in light output. Upgrading to a 4.2 W LED pushed things even further, greatly improving the look of the lamp.

The video also explores modding a modern fiber optic lamp, too. It was incredibly cheap, running off batteries and using a single color-changing LED to illuminate the fibers. [Braniac75] decided to try illuminating the plastic fibers with an RGB stage lighting laser rig—namely, the LaserCube Ultra 7.5 W from Wicked Lasers. With this kind of juice, the fiber lamp is eye-searingly bright, quite literally, and difficult to film. However, with the laser output dialed way down, the lamp looks amazing—with rich saturated colors dancing across the fiber bundle as the lasers do their thing.

If you’ve ever wanted to build a fiber lamp that doesn’t look like a cheap gimmick, now you know how. We’ve looked at weird applications for these lamps before, too.

Continue reading “Fiber Optic Lamp Modified To Be Scarily Bright” →

Building Beautiful LED Lanterns With Black LED Acrylic

December 27, 2025 by Lewin Day 8 Comments

[Geeksmithing] and [When Geeks Craft] recently came together for a glowing collaboration. They wanted to build ever more attractive lanterns for a local parade event. They recently discovered a fantastic material that can really improve the look of whatever project you might be building with LEDs.

The material is commonly referred to as “Black LED Acrylic” or similar. In this case, it was sourced from TAP Plastics, though you can source similar acrylic from other vendors, too. From first glance, it looks like any other piece of black acrylic plastic. However, shine an LED through it, and it will be beautifully diffused and smoothed out to wonderful visual effect. A simple test of a 3×3 array of LEDs behind a 3D-printed grid shows how good this can look. It almost entirely eliminates hot spots, and the result looks like a display built out of juicy glowing cubes. The duo used this material to produce giant pixel art lanterns for their local parade. We only get a glimpse at the final build, but it appears giant Pacman and Blinky totems are on the way.

If you’ve been struggling to find a good way to diffuse the light from LEDs, you might want to give this stuff a try. Alternatively, you might explore some other methods we’ve looked at before, and don’t discount ping pong balls, either.

Continue reading “Building Beautiful LED Lanterns With Black LED Acrylic” →

Print Your Next LED Bezel

December 27, 2025 by Donald Papp 6 Comments

LED bezels (also known as LED panel-mount holders) are great, so how about 3D printing the next ones you need? Sure, they’re inexpensive to purchase and not exactly uncommon. But we all know that when working on a project, one doesn’t always have everything one might need right at hand. At times like that, 3D printing is like a superpower.

Printing a part you find yourself short of can be a lifesaver.

[firstgizmo]’s design is made with 3D printing in mind, and most printers should be able to handle making them. Need something a little different? You’re in luck because the STEP files are provided (something we love to see), which means modifications are just a matter of opening them in your favorite CAD program.

There’s not even any need to export to an STL after making tweaks, because STEP support in slicer programs is now quite common, ever since PrusaSlicer opened that door a few years ago.

Not using 5 mm LEDs, and need some other size? No problem, [firstgizmo] also has 3 mm, 8 mm, and 10 mm versions so that it’s easy to mount those LEDs on a panel. Combined with a tool that turns SVG files into multi-color 3D models, one can even make some panels complete with color and lettering to go with those LEDs. That might be just what’s needed to bring that midnight project to the next level.