LED Hacks

1889 Articles

Building A Minecraft Lantern For Halloween

October 21, 2025 by 5 Comments

Sometimes it’s fun to bring props from video games into the real world. [Hulk] has done just that with their latest Halloween build—creating a working replica of the lantern from Minecraft.

Key to the build is the 3D printed enclosure, which faithfully mimics the look of the in-game item. By virtue of Minecraft’s simplistic visual style, it’s a relatively straightforward print, without a lot of quirky geometry or difficult overhangs that might otherwise trip up your printer. It’s printed in six parts and assembled with acrylic lenses which act to diffuse the light coming from inside.

Electronically, an Arduino Nano runs the show. It’s hooked up to a pair of NeoPixel addressable LED rings, which provide rich RGB colors on demand. Rotary pots are installed on the enclosure to enable the color to be tuned to the user’s desire. Power is courtesy of an 18650 lithium-ion cell and a TP4056 module ensures the battery is kept happy when charging.

It’s a fun prop build, and one that would be the perfect addition to any Minecraft costume. Except for maybe a chicken jockey, because they don’t use lanterns. In any case, we’ve seen similar work before, too.

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Don’t Believe Planck’s Constant? Measure It Yourself

October 20, 2025 by 12 Comments

We aren’t sure if [Looking Glass Universe] didn’t trust the accepted number for Planck’s constant, or just wanted the experience of measuring it herself. Either way, she took some LEDs and worked out the correct figure. Apparently, it hasn’t changed since we first measured it in 1916. But it’s always good to check.

The constant, if you need a refresher, helps explain things like why the color of light changes how the photoelectric effect manifests, and is at the root of quantum physics. LEDs are perfect for this experiment because, of course, they come in different colors. You essentially use a pot to tune down the LED until it just reaches the point where it is dark. Presuming you know the wavelength of the LED, you can estimate Planck’s constant from that and the voltage across the virtually ready-to-light LED. We might have used the potentiometer in a voltage divider configuration, but it should work either way.

The experiment showed that even a disconnected LED emits a few stray photons. But it was still possible to interpret the results. The constant is very tiny, so you’ll want your scientific calculator get do the math or, as she used, Wolfram Alpha.

The first result was off by the alarming amount of 1 x 10-40. No, that’s not alarming at all. That number is amazingly small.

This is a fairly common home physics experiment. You can do it quick, like [Looking Glass] did, or you can build something elaborate.

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A hand holding the circuit in its active state

2025 Component Abuse Challenge: A Self-Charging LED Flasher By Burkhard Kainka

October 18, 2025 by 8 Comments

[Tito] entered a Self-Charging LED Flasher into the Component Abuse Challenge. It’s a simple re-build of a design by the unstoppable [Burkhard Kainka], and while [Tito] doesn’t explain its workings in detail, it’s a clever experiment in minimalism, and a bit of a head-scratcher at the same time.

You press a button and an LED flashes.  But there is no battery, so how does it work? Maybe the schematic to the right here will help. Or does it confound? Look at it yourself before reading on and see if you can figure out how it works.

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An LED Sphere For Your Desk

September 27, 2025 by 1 Comment

The Las Vegas Sphere is great and all, but few of us can afford the expense to travel to out there to see it on the regular. If you’re looking for similar vibes you can access at home, you might enjoy the desk toy that [AGBarber] has designed.

The scale is small — the sphere measures just 98 mm (3.6 inches) in diameter — but that just means it’s accessible enough to be fun. The build is based around various sizes of WS2812B addressable LED rings, and contains 120 individual RGB LEDs in total. They’re wrapped up in a 3D printed housing which does a great job of diffusing the light. Transparent filament was used to print parts that light up with a richly-saturated glow with few visible hotspots. Commanding the LEDs is an ESP8266 microcontroller in the form of a Wemos D1 Mini, which provides plenty of grunt to run animations as well as great wireless connectivity options. [AGBarber] relied on their own Pixel Spork library to handle all the cool lighting effects. Files are on GitHub for the curious.

Maybe you don’t like spheres, and icosahedrons are more your speed. Well, we’ve featured those too—with 2,400 LEDs, no less.

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The schematic on the left and the assembled circuit on the right.

How To Make A Simple MOSFET Tester

September 13, 2025 by 22 Comments

Over on YouTube our hacker [VIP Love Secretary] shows us how to make a simple MOSFET tester.

This is a really neat, useful, elegant, and simple hack, but the video is kind of terrible. We found that the voice-over constantly saying “right?” and “look!” seriously drove us to distraction. But this is a circuit which you should know about so maybe do what we did and watch the video with subtitles on and audio off.

To use this circuit you install the MOSFET you want to test and then press with your finger the spare leg of each of two diodes; in the final build there are some metal touch pads attached to the diodes to facilitate this. One diode will turn the MOSFET off, the other diode will turn the MOSFET on, and the LED will show you which is which.

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Inside and outside the Contrib Cal.

Reify Your GitHub Commit History With Contrib Cal

September 12, 2025 by 3 Comments

Over on Instructables, [Logan Fouts] shows us the Contrib Cal GitHub desk gadget. This build will allow you to sport your recent GitHub commit activity on your wall or desk with an attractive diffuse light display backed by a 7×4 matrix of multicolor LEDs. Motivate yourself and impress your peers!

This humble project is at the same time multifaceted. You will build a case with 3D printing, make a diffuse screen by gluing and cutting, design a LED matrix PCB using KiCad, solder everything together, and then program it all with Python. The brains of the operation are a Raspberry Pi Zero W.

The Instructables article will run you through the required supplies, help you to print the case, explain how to solder the LEDs, tell how to install the heat-set inserts for high quality screw attachments, explain wiring and power, tell you about how to use the various screws, then tell you about where to get more info and the required software on GitHub: Contrib Cal v2.

Of course this diffuse LED matrix is only one way to display your GitHub progress, you can also Track Your GitHub Activity With This E-Ink Display.

Scott and his Prompt 80

Restoring A Vintage Intel Prompt 80 8080 Microcomputer Trainer

September 3, 2025 by 3 Comments

Over on his blog our hacker [Scott Baker] restores a Prompt 80, which was a development system for the 8-bit Intel 8080 CPU.

[Scott] acquired this broken trainer on eBay and then set about restoring it. The trainer provides I/O for programming, probing, and debugging an attached CPU. The first problem discovered when opening the case is that the CPU board is missing. The original board was an 80/10 but [Scott] ended up installing a newer 80/10A board he scored for fifty bucks. Later he upgraded to an 80/10B which increased the RAM and added a multimodule slot.

[Scott] has some luck fixing the failed power supply by recapping some of the smaller electrolytic capacitors which were showing high ESR. Once he had the board installed and the power supply functional he was able to input his first assembly program: a Cylon LED program! Making artistic use of the LEDs attached to the parallel port. You can see the results in the video embedded below.

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