Two Microcontrollers Talking, All It Needs Is An LED

October 5, 2026 by Jenny List 10 Comments

There are some projects that seem at first sight to be easy, but anyone who tries them finds a whole heap of unexpected problems and turns to the off-the-shelf device. PCB antennas for example, or data links using LEDs, whether IR or visible. The latter doesn’t faze [Luca Soltoggio] though, because he has two ESP32s talking to each other using visible light. Best of all, both use a single LED as both transmitter and receiver.

The software is called SecurePair, and is an Arduino library for exchanging keys and communicating with encryption. The LEDs are the cool hardware hack but it’s designed to work with ESPNow or LoRa too, indeed a typical use case would see light for pairing and wireless for the exchange of encrypted data.. In case you were wondering, it relies on the property of an LED that it’s also a photodiode of sorts. Best of all, while the examples have two ESP32s, it’s not limited to that number and many more can join the conversation if needed.

Check out the video below to see it in action — if you’re curious about LEDs as sensors, we’ve been there too.

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ESP32 Replacement For Lighting Display Controller

September 22, 2026 by Bryan Cockfield 1 Comment

As a company, NanoLeaf has been producing modular lights that can be easily snapped together into various geometric shapes for around a decade. Similar to the addressable LED light strips many of us are familiar with that also became popular around a decade ago, these modular lights are supposed to be easy to configure, customize, and program. But their controllers are notoriously finicky according to [Myrik] who found that a simple ESP32 could be used to replace them when they eventually fail.

Part of the reason [Myrik] found this to be straightforward is that the company publishes their firmware and makes it essentially available to anyone. Whether or not this was purposeful is not clear; but in either case it only requires slight modification to run on the ESP32. When plugged into an existing string of panels, the panels themselves report their positions and orientations over a single data bus which the ESP32 has no problem interpreting. The ESP32 can also communicate its status over the network, meaning that it can in turn be controlled by any other lighting software a user might have.

There’s a separate Reddit post about this build as, with other users offering other potential solutions to the controller issue. But we are always happy to see more open solutions to hardware failures which keep interesting things like these out of the e-waste pile, or simply building NanoLeaf-inspired replicas from the ground up in the first place.

Big Infinity Mirror Clock Invites You To Gaze Deeply

September 12, 2026 by Donald Papp 10 Comments

[Andy Huot] has a fantastic-looking infinity mirror digital clock that really raises the bar. It uses high quality components, smart use of RGB LED animations, and a clever “stacked diffuser” vertical design to the 7-segment display elements that really enhances the infinity mirror effect. It needs to be seen in action, so check it out.

The end result is expressly portal-like, with the smooth animations of the LEDs really playing into the effect. The size helps, too. It’s 24 inches in diameter, giving it considerable presence.

The stacked diffuser design for each display element really enhances the effect.

A basic infinity mirror design consists of lit elements sandwiched between a reflective back surface and a partially-reflective, partially-transmissive top cover. That same basic principle is used here, but with great care given to ensure nothing so much as a fingerprint spoils the illusion. For example, the top cover is a disk of acrylic with a 90% reflective film affixed to the inside surface. That’s easy enough to DIY with some car tint, but [Andy] found that for the very best results it was worth having high-quality film professionally applied.

We like the use of 3D-printed custom jigs for soldering the segments of RGB LED strips, and holding the pre-measured wires in place with some putty is a great way to keep them in place while working. In case you’re wondering, the mirrored acrylic making up the back wall has holes in it for mounting each segment’s LED strip in a holder, and running the wires to the rear.

The video (embedded below) documents every step of the assembly, and it’s a serious build. While the design files for the 3D-printed parts are not free, there’s certainly enough detail for an enterprising hacker to replicate the design in their own way.

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Custom AMOLED Wearable Makes Great Icebreaker

September 10, 2026 by Donald Papp 12 Comments

Nifty little AMOLED screens are easy to get nowadays, and [Sophie D] demonstrates they are both thin and light enough to be worn with OpenChoker, a design for a choker necklace that was a hit at DEF CON.

The choker consists of an AMOLED touchscreen flanked by short RGB LED strips. Behind the display is the PCB which contains an RP2350 and micro SD card slot for external storage, and at the rear of the choker is an 18650 cell to power it all. The display plays an eye-catching animation that gets generated on the fly while the LEDs sparkle away.

[Sophie] shares a number of interesting takeaways from designing and building this device. One is that the bulk of the PCB design work was interfacing to the display, since no existing footprint or reference design could be found. So if you find yourself with a Hello Lighting HL020E21-02 2.14″ touchscreen display you’re hankering to use in your own project, do yourself a favor and check out [Sophie]’s board design instead of starting from scratch.

Battery life was more than enough for a device like this. A single 18650 cell powered the choker effortlessly for a 16-hour stretch and still the cell measured a robust 3.7 V. While a light-up choker used indoors isn’t a great candidate for wearable solar power, it’s encouraging that there’s no need for a tethered battery pack.

Another tip to consider relates to the screen’s touch sensitivity. In short, the capacitive touch screen responded perfectly when plugged into a development computer, but when mounted and isolated on the choker it responded so poorly as to be useless. It didn’t keep the rest of the choker from doing its job, but it might be worth keeping in mind as something to watch out for with a device like this.

There’s one final mystery [Sophie] ran into: with only one day to spare, glue used to affix some wires ended up melting away the wire insulation, revealing bare copper. We’re not sure what happened there, but if nothing else it’s a reminder that Murphy’s Law is always ready to strike when one is on a deadline.

Parchment Paper Paired With 3D-Printed Grid Gives A Nice Glow

September 4, 2026 by Donald Papp 14 Comments

This custom enclosure for a 64×64 RGB LED matrix by [Davisan1001] not only provides a mount point for a Raspberry Pi, but presents a clean and smooth face with square pixels thanks to a 3D-printed grid, some parchment paper, and a sheet of clear plastic.

The first clever thing in this design is the way [Davisan1001] created the grid that acts as a light blocker for each LED in the matrix, preventing light from “spilling” over into its neighbors. Instead of designing the grid from scratch, the solution was just to leverage slicer settings. By printing a flat square with a grid pattern infill and zero solid top and bottom layers, the slicer creates the grid all by itself. A little trial and error was required to get the spacing just right, but it seems to have worked out fine. We’re not sure it’s better than designing a grid in CAD, but it was certainly a clever way to avoid having to do so.

[Davisan1001] also struggled to find an effective and economical solution for a diffuser. Certainly, high-quality diffuser films are available for sale, as are specialty acrylic sheets, but surely there was some household DIY option to do the trick. A sheet of plain white paper blocks too much light. Wax paper handles poorly, and off-angle viewing is poor. The sweet spot was parchment paper.

Parchment paper is commonly used in baking and is thin, easy to handle, flat and even in color, and just opaque enough to act as an effective diffuser while still transmitting enough light to not impede clarity. Cover the LED matrix with the 3D-printed grid, lay parchment paper over that, cover with a sheet of clear plastic, and the job is done.

Light diffusion can be tricky to get just right in a DIY project, and what works for one application won’t necessarily work for another. Our community had loads of suggestions on different solutions, so consider this one more idea to try the next time you have a project that calls for it.

Sliding Into Perfection: The Open Task Light

September 1, 2026 by Matt Varian 29 Comments

A few years ago Dyson released a desk lamp that could slide up and down, in and out, balancing itself at every position. [Steven Bennett] saw that lamp and wanted to make his own. From this passion, the Open Task Light was born.

We covered the prototype of the Open Task Light back in 2023, and the project is a superb example of iteration. In his 15-part video series on the lamp, you can watch him take on each new aspect of the light, improving the mechanisms, electronics, and production. All those small changes add up to this beautifully finished product.

The first thing you’ll notice about the lamp is how little there is to notice: just a pair of extruded aluminum rails with a lamp head on one end and some rollers in the middle. Look a little closer at the rail and you’ll find a PCB running its length, feeding the lamp through pogo pins and leaving no exposed wires. The lamp uses a heat pipe to dump the LED’s heat, again hidden inside the aluminum extrusion. An ESP32 talks to a dedicated LED driver that runs a Cree high-CRI LED. The base comes in several variations for freestanding use or clamping to a table, and it rides on bearings so it can rotate as freely as the lamp’s other axes of movement.

The original lamp this was inspired by carries a hefty price tag, and while the 50-plus-part BOM on this one adds up, it still comes in at well under half the price of its inspiration. The best part: the Open Task Light is open. You can make it your own, head over to [Steven Bennett]’s GitHub to check out the parts. He has also published a well-documented guide on assembling the Open Task Light.

Given the incredible work [Steven] has put into his lamp, we can’t wait to see his next passion project.

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Building An Energy-Harvesting Business Card

August 31, 2026 by Zoe Skyforest 12 Comments

The hope is always that a good business card will leave a good impression. For those in the electronics field, they also serve as an opportunity to showcase creative design skills. [Wilson Harper] demonstrates that ably with a rather nifty energy-harvesting build.

The card is based around a thin PCB in the typical business card size. It’s populated by 21 Charlieplexed LEDs, a small microcontroller, and some supporting components. Now, this is normally where you might expect the device to be powered by a small coin cell, maybe deftly integrated into the PCB thickness itself to make the card less cumbersome. But no—[Wilson] went a different route. The thing is that in 2026, most of us are carrying phones with NFC readers built in. Thus, the card was built to harvest this source of energy with a PCB trace antenna, designed with the aid of STM’s antenna inductance tools and an LLM script lobbed into KiCad. All one needs to do is to pop the card on the back of a phone and the LEDs animate joyfully.

Design files are on Github for the curious. You might also like to check out some of the fancy business cards we’ve featured in the past. Of course, if you’re working on just such a project yourself, you’re more than welcome to send it in to the tipsline!