Modded Lightbox Makes For Attractive LED Matrix Display

February 24, 2026 by Lewin Day 1 Comment

If you’ve been to a wedding or a downtown coffee shop in the last 10 years, you’ve probably seen those little lightboxes that are so popular these days. They consist of letters placed on a plastic frame in front of a dim white light, and they became twee about five minutes after your hipster friend first got one. However, they can also make a neat basis for an LED display, as [Folkert van Heusden] demonstrates.

The build is straightforward enough, using daisy chains of 32×8 LED matrix modules, two each for the three rows of the lightbox. This provides for a 24 character textual display, or a total display resolution of 64 x 24 pixels. An ESP8266 is used to command the matrixes, which are run by MAX7219 display controllers. Thanks to the microcontroller’s onboard wireless hardware, the display can be addressed in a number of ways, such as using the LedFX DDP protocol or [Folkert’s] Pixel Yeeter python library. Files are on GitHub for the curious.

Quite a few of these exist out in the wild — [Folkert] has built a variety of modded lightboxes over the years with varying internals. The benefit of the lightbox is that it effectively acts as a handy housing for LED matrixes and supporting electronics, while also providing a neat diffuser effect. The lightboxes are also readily wall mountable and generally look more like an intentional piece of signage than most things we might homebrew in the lab.

We’ve featured similar-looking builds before, like this public transit display that was hacked for custom use. If you’re building your own public information boards or other nifty LED displays, don’t hesitate to notify the tipsline!

A Candle-Powered Light

February 23, 2026 by Bryan Cockfield 24 Comments

For a little over two thousand years, the primary light sources after the sun had set were oil lamps and candles. This was well before the age of fossil fuels, so these oil lamps were often fueled with a labor-intensive agricultural product like olive oil. Candles were similarly difficult to make, made from tallow, beeswax, or even butter. Labor and materials costs aside, though, there’s a surprising amount of energy in these fuels and [Maciej Nowak Projects] has a generator that help these ancient light sources generate some electricity on the side.

The generator is based around a piece of technology called a thermoelectric generator (TEG), which produces a voltage potential when placed in a temperature gradient. These aren’t new technologies, but their typically low efficiencies limit where they can be effectively used. In this case, however, [Maciej Nowak] has gone to great effort to boost this efficiency as high as possible by using a huge radiator on the cool side of the TEG and another one on the hot side, which in this case is heated by a small tea candle. The electricity produced is sent to a tiny DC converter which regulates the voltage to 3.3V, which then powers two custom-built pedestal lamps on either side of the TEG, each with a high-efficiency LED mounted to a custom-made circuit board.

Although this is certainly not the first time a TEG has been set up to run a small lighting system, we do appreciate this one for its polish, design, and high efficiency. It would make a fitting addition to anyone’s emergency power outage kit as it really increases the amount of available light produced from any given candle. When taken to the extreme, though, thermoelectric generators can be made to produce a surprising amount of energy, provided they are placed in the right environment.

Continue reading “A Candle-Powered Light” →

Real LED TVs Are Finally Becoming A Thing

February 16, 2026 by Lewin Day 53 Comments

Once upon a time, the cathode ray tube was pretty much the only type of display you’d find in a consumer television. As the analog broadcast world shifted to digital, we saw the rise of plasma displays and LCDs, which offered greater resolution and much slimmer packaging. Then there was the so-called LED TV, confusingly named—for it was merely an LCD display with an LED backlight. The LEDs were merely lamps, with the liquid crystal doing all the work of displaying an image.

Today, however, we are seeing the rise of true LED displays. Sadly, decades of confusing marketing messages have polluted the terminology, making it a confusing space for the modern television enthusiast. Today, we’ll explore how these displays work and disambiguate what they’re being called in the marketplace.

Continue reading “Real LED TVs Are Finally Becoming A Thing” →

LED Interior Lighting Could Compromise Human Visual Performance

February 3, 2026 by Lewin Day 67 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!

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” →

Different Algorithms Sort Christmas Lights

December 29, 2025 by Bryan Cockfield 10 Comments

Sorting algorithms are a common exercise for new programmers, and for good reason: they introduce many programming fundamentals at once, including loops and conditionals, arrays and lists, comparisons, algorithmic complexity, and the tradeoff between correctness and performance. As a fun Christmas project, [Scripsi] set out to implement twelve different sorting algorithms over twelve days, using Christmas lights as the sorting medium.

The lights in use here are strings of WS2812 addressable LED strips, with the program set up to assign random hue values to each of the lights in the string. From there, an RP2040-based platform will step through the array of lights and implement the day’s sorting algorithm of choice. When operating on an element in the array the saturation is turned all the way up, helping to show exactly what it’s doing at any specific time. When the sorting algorithm has finished, the microcontroller randomizes the lights and starts the process all over again.

For each of the twelve days of Christmas [Scripsi] has chosen one of twelve of their favorite sorting algorithms. While there are a few oddballs like Bogosort which is a guess-and-check algorithm that might never sort the lights correctly before the next Christmas (although if you want to try to speed this up you can always try an FPGA), there are also a few favorites and some more esoteric ones as well. It’s a great way to get some visualization of how sorting algorithms work, learn a bit about programming fundamentals, and get in the holiday spirit as well.

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” →