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!

Hackaday Podcast Episode 355: Person Detectors, Walkie Talkies, Open Smartphones, And A WiFi Traffic Light

January 30, 2026 by Jenny List No comments

Another chilly evening in Western Europe, as Elliot Williams is joined this week by Jenny List to chew the fat over the week’s hacks.

It’s been an auspicious week for anniversaries, with the hundredth since the first demonstration of a working television system in a room above a London coffee shop. John Logie Baird’s mechanically-scanned TV may have ultimately been a dead-end superseded by the all-electronic systems we all know, but the importance of television for the later half of the 20th century and further is beyond question.

The standout hacks of the week include a very clever use of the ESP32’s WiFi API to detect people moving through a WiFi field, a promising open-source smartphone, another ESP32 project in a comms system for cyclists, more cycling on tensegrity spokes, a clever way to smooth plaster casts, and a light sculpture reflecting Wi-Fi traffic. Then there are a slew of hacks including 3D printed PCBs and gem-cut dichroic prisms, before we move to the can’t-miss articles. There we’re looking at document preservation, and a wallow in internet history with a look at the Netscape brand.

As usual all the links you need can be found below, so listen, and enjoy!

Or download the podcast old-school, with a direct link to the MP3 file in question.

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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.

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Light Following Robot Does It The Analog Way

January 28, 2026 by Lewin Day 12 Comments

If you wanted to build a robot that chased light, you might start thinking about Raspberry Pis, cameras, and off-the-shelf computer vision systems. However, it needn’t be so complex. [Ed] of [Death and the Penguin] demonstrates this ably with a simple robot that finds the light the old-fashioned way.

The build is not dissimilar from many line-following and line chasing robots that graced the pages of electronics magazines 50 years ago or more. The basic circuit relies on a pair of light-dependent resistors (LDR), which are wrapped in cardboard tubes to effectively make their response highly directional. An op-amp is used to compare the resistance of each LDR. It then crudely steers the robot towards the brighter light between turning one motor hard on or the other, operating in a skid-steer style arrangement.

[Ed] then proceeded to improve the design further with the addition of a 555 timer IC. It’s set up to enable PWM-like control, allowing one motor to run at a lower speed than the other depending on the ratio between the light sensors. This provides much smoother steering than the hard-on, hard-off control of the simpler circuit. [Ed] notes that this is about the point where he would typically reach for a microcontroller if he hoped to add any additional sophistication.

In an era where microcontrollers seem to be the solution to everything, it’s nice to remember that sometimes you can complete a project without using a processor or any code at all. Video after the break.

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Robot Sees Light With No CPU

January 19, 2026 by Al Williams 10 Comments

If you ever built a line following robot, you’ll be nostalgic about [Jeremy’s] light-seeking robot. It is a very simple build since there is no CPU and, therefore, also no software.

The trick, of course, is a pair of photo-sensitive resistors. A pair of motors turns the robot until one of the sensors detects light, then moves it forward.

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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.

Lichtenberg Lightning In A Bottle, Thanks To The Magic Of Particle Accelerators

December 22, 2025 by Tyler August 14 Comments

You’ve probably seen Lichtenberg figures before, those lightning-like traces left by high-voltage discharge. The safe way to create them is using an electron beam to embed charge inside an acrylic block, and then shake them loose with a short, sharp tap. The usual technique makes for a great, flat splay of “lightning” that looks great in a rectangular prism or cube on your desk. [Electron Impressions] was getting bored with that, though, and wanted to do something unique — they wanted to capture lightning in a bottle, with a cylindrical-shaped Lichtenberg figure.

They’re still using the kill-you-in-milliseconds linear accelerator that makes for such lovely flat figures, but they need to rotate the cylinder to uniformly deposit charge around its axis. That sounds easy, but remember this is a high-energy electron beam that’s not going to play nice with any electrical components that are put through to drive the spinning.

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