Tiny Tiny RGB LED Displays

Hackaday.io contributor extraordinaire [al1] has been playing around with small LEDs a lot lately, which inevitably leads to playing around with large groups of small LEDs. Matrixes of tiny RGB LEDs, to be precise.

Where's the LED?
Where’s the LED?

First, he took 128 0404 SMD RGB LEDs (yes, 40 thousandths of an inch on each side) and crammed them onto a board that’s just under 37 mm x 24 mm. He calls the project 384:LED (after all, each of those 128 packages has three diodes inside). A microcontroller and the driver chips are located on a separate driver board, which piggy-backs via pin headers to the LED board. Of course, he had to use 0.05 inch headers, because this thing is really small.

Of course, no project is without its hitches. [al1] bought LEDs with the wrong footprint by mistake, so he had a bunch of (subtly different) 0404 LEDs left over. Time for an 8×8 matrix! 192:LED isn’t just the first project cut in half, though. It’s a complete re-design with a four-layer board and the microcontroller on the back-side. And as befits a scrounge project with lots of extreme soldering, he even pulled the microcontroller off of a cheap digital FM radio. Kudos!

We’re in awe of [al1]’s tiny, tiny hacking skills. Now it’s time to get some equally cool graphics up on those little displays.

Rainbow Cats Announce Engagement

[ANTALIFE] is going to tie the knot sometime in 2017. Instead of sending out paper announcements or just updating his Facebook status, he wanted to give their family members something lasting and memorable, like a small trinket with a pair of light-up cats.

This project is pretty simple in theory. A pair of RGB LEDs cycle through the colors of the rainbow with the help of an ATtiny25 and resistors carefully chosen for each LED. But there are several challenges at play here. [ANTALIFE] wanted to design something quite small that would last at least a day on a single CR2032 coin cell. This project was his first foray into SMD/SMT design and construction. We think that this warrants its own congratulations, especially since it looks as though he made at least a dozen of these things.

[ANTALIFE] made things much easier for himself with the purchase of a cheap hot air rework station and used a chip clip to program the ‘tiny. The cats are a design from Thingiverse, which he modified to turn them into bride and groom. Watch a whole line of them glow after the break. We sincerely hope that a larger version of these cats end up on top of the wedding cake.

For anyone with an undying love blinkenlights and impending nuptials, don’t forget the light-up invitations, wedding attire, and centerpieces.

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8-bit Video Wall Made From 160 Gaming Keyboards

Well this is something we haven’t seen before. A video wall An 8-bit style video wall made from 160 RGB illuminated gaming keyboards.

On display at the PAX East gaming expo, the keys on 160 Logitech keyboards make up the “pixels” of a video wall showing a short film inspired from side-scroller video games. It’s the work of the production company iam8bit. Details on the system are scant, but we can learn a little from close observation of the video.

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Beautiful Weather Station uses Acrylic, RGB LED, and and ESP8266

Everyone knows there’s form and there’s function. It isn’t fair, but people do judge on appearance, sometimes even overriding all other concerns. So while your Makerspace buddies might be impressed by your weather station built on a breadboard, your significant other probably isn’t. [Dennisv15] took an ordinary looking weather station design with a 0.96″ display and turned into an attractive desk piece with a much larger display and an artistic–and functional–enclosure.

The acrylic cloud lights up thanks to an RGB LED Neopixel strip and can indicate weather trends at a glance: red for warmer, blue for colder, flashing for inclement weather. The project was truly multidisciplinary, using a laser cutter to produce the body and the stand, a 3D-printed display bezel, and a PCB to make it easy to build.

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Controlling RGB LEDs With The Pi Zero

The Pi Zero is a great piece of hardware, even if you’re not designing another USB hub for it. [Marcel] wanted to control a few RGB LED strips from his phone, and while there are a lot of fancy ways you can do this, all it really takes is a Pi Zero and a few parts that are probably already banging around your parts drawers.

This isn’t a project to control individually addressable RGB LEDs such as NeoPixels, WS2812s, or APA102 LEDs. This is just a project to control RGB LEDs with five four connectors: red, green, blue, power, and or ground. These are the simplest RGB LEDs you can get, and sometimes they’re good enough and cheap enough to be the perfect solution to multi-colored blinkies in a project.

Because these RGB LEDs are simple, that means controlling them is very easy. [Marcel] is just connecting a transistor to three of the PWM pins on the Pi and using a TIP122 transistor to drive the red, green, and blue LEDs. You’ve got to love those TIPs package parts!

Control of the LEDs is accomplished through lighttpd. This does mean a USB WiFi dongle is required to control the LEDs over the Internet, but it is so far the simplest way we’ve seen to add multicolor blinkies to the web.


The Raspberry Pi Zero contest is presented by Hackaday and Adafruit. Prizes include Raspberry Pi Zeros from Adafruit and gift cards to The Hackaday Store!
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Building The World’s Smallest RGB LED Cube

What’s the smallest RGB LED cube? A 1x1x1 cube is easy, but it’s a stupid joke and we’ve heard it before. No, to build the smallest LED cube, you’ll have to stuff 64 RGB LEDs into a cubic inch, like [Hari] did with his miniscule LED cube.

A single column of Charlieplexed LEDs. Note the resistor for scale.
A single column of Charlieplexed LEDs. Note the resistor for scale.

One might think that individually addressable RGB LEDs are the way to go with an LED cube this small. Anything else would hide the LEDs behind a mess of wires. This isn’t the case with [Hari]’s LED cube – he’s using standard surface mount RGB LEDs for this build. But how is he connecting the things?

The entire build was inspired by the a much earlier project, the Charliecube. This LED cube, like [Hari]’s uses Charlieplexing to condense all the connections for a column of LEDs to only four wires. Repeat that sixteen times, and [Hari] built himself a tiny, one-inch cube of glowey goodness.

The cube itself was built with a PCB backplane designed in Eagle and fabbed at OSHPark. The LEDs are driven by an Arduino Nano. If you’d like to build your own, or you’re a masochist for dead bug soldering, you can grab all the design files over on [Hari]’s hackaday.io project page.

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Recursive Soldering Iron Hacking

We’ve all done it. You’re walking out the door or maybe you’ve even gotten on the road when the question hits, “Did I leave the [coffee pot | stove | hair curler | soldering iron ] on?” [Daniel Johnson’s] problem was even worse. He couldn’t tell if his Hakko-936 soldering iron was off because the LED indicator wasn’t always on. Instead it flashed. He fixed that problem and along the way hacked his battery powered soldering iron since he was out of batteries. Now that’s perseverance.

Hacked Soldering Iron to Hack Soldering Iron
Soldering Iron Hack Recursion

The Hakko’s LED turned on whenever the power turned on to heat the tip. That was about every 5 seconds once the tip was hot. But just as a watched pot never boils, a watched LED never seems to flash. After determining the LED was driven by a comparator he decide to unsolder it as part of his hack. He wisely decided using the Hakko on itself was not a good idea so reached for the battery-powered portable iron, which was sadly battery-free. Undaunted, he wired the portable to a power supply and when 4.5 volts didn’t melt the solder cranked it up to 6 volts.

Back to the Hakko, he replaced the red LED with a RBG LED but used only the red and green leads. The green was tied to the 24v power supply through a hefty 47k ohm resistor, and the red was tied to the comparator. A little masking tape to hold things in place and provide insulation finished the job. Now when the Hakko is on the green LED is lit and the red LED shows the heating cycle. Quite clever.