You would think that there’s nothing to know about RGB LEDs: just buy a (strip of) WS2812s with integrated 24-bit RGB drivers and start shuffling in your data. If you just want to make some shinies, and you don’t care about any sort of accurate color reproduction or consistent brightness, you’re all set.
But if you want to display video, encode data in colors, or just make some pretty art, you might want to think a little bit harder about those RGB values that you’re pushing down the wires. Any LED responds (almost) linearly to pulse-width modulation (PWM), putting out twice as much light when it’s on for twice as long, but the human eye is dramatically nonlinear. You might already know this from the one-LED case, but are you doing it right when you combine red, green, and blue?
It turns out that even getting a color-fade “right” is very tricky. Surprisingly, there’s been new science done on color perception in the last twenty years, even though both eyes and colors have been around approximately forever. In this shorty, I’ll work through just enough to get things 95% right: making yellows, magentas, and cyans about as bright as reds, greens, and blues. In the end, I’ll provide pointers to getting the last 5% right if you really want to geek out. If you’re ready to take your RGB blinkies to the next level, read on!
Word clocks are cool, but getting them to function correctly and look good is all about paying attention to the details. One look at this elegant walnut-veneered word clock shows what you can accomplish when you think a project through.
Most word clocks that use laser-cut characters like [grahamvinyl]’s effort suffer from the dreaded “stencil effect” – the font has bridges to support the islands in the middle of characters like “A” and “Q”. While that can be an aesthetic choice and work perfectly well, like in this word clock we featured a few months back, [grahamvinyl] was going for a different look. The clock’s book-matched walnut guitar back was covered in tape before being laser cut; the tape held the letters and islands in place. After painstakingly picking out the cutouts and tweaking the islands, he used clear epoxy resin to hold everything in place. The result is a fantastic Art Deco font and a clean, sleek-looking panel to sit on top of an MDF light box for the RGB LED strips.
The braided cloth cable adds a vintage look to the power cord, and [grahamvinyl] mentions some potential upgrades, like auto-dimming and color shifting. This is very much a work in progress, but even at this point we think it looks fabulous.
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.
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.
[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.
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.
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.
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.