Building Huge Displays With LED Strips

February 25, 2013 by Brian Benchoff 58 Comments

Building RGB LED displays is one of the most interesting programming and engineering challenges we see here on Hackaday. Not only do the creators of large displays and LED cubes have to deal with the power requirements of driving a whole bunch of LEDs, but there’s also the issue of getting the frame rate high enough to display video. It’s a non-trivial task, but [Paul Stoffregen] has an interesting solution. He wrote an LED strip library that can control eight meter-long LED strips that can also be used on daisy chained Teensy 3.0 microcontrollers for really large displays.

[Paul]’s LED library works with LED strips based on the WS2811 LED controller IC. These chips are the most common controller chips for the individually controllable LED strips you can find at Adafruit or hundreds of Chinese resellers. The library requires DMA transfer to display images, so if you’re looking to build a ginormous RGB LED display, you might want to pick up a few of [Paul]’s Teensy 3.0 boards

[Paul] also created a Processing app that takes a video file and turns it into serial data for his LED strip library. You can check out a video of this app, library, and a 60×32 RGB LED display after the break.

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LED Marquee Uses Discrete Through-hole Lights

February 21, 2013 by Mike Szczys 29 Comments

through-hole-led-marquee

[Michael] built his own LED marquee using individual diodes. Despite his choice to forego the 8×8 or 5×7 modules we often see in these projects, his decision to spin a dedicated PCB saved him a lot of trouble during assembly. Sure, he still had to solder 180 leads on the 9×18 grid of lights, but at least he didn’t have to deal with wiring up the complex display layout.

The chip driving the display is an ATtiny24. You can see that it’s an SMD package and spans one row of the through hole LED footprint. There are way too few pins to drive a multiplexed display of this size. Instead of adding a separate driver IC he decided to design the display to use Charlieplexing. We didn’t see a schematic for the project, but judging from the board images all of the I/O pins are used by either the display itself, or the serial connection provided by that right angle pin header.

Wall-wart Retrofitted With A High-power LED Supply Circuit

February 13, 2013 by Mike Szczys 10 Comments

high-power-LED-wall-wart-supply

This custom circuit board picks up some of the pieces from a wall wart to drive a high-power LED. The basic concept is to keep the high-voltage components and swap out the low voltage ones for parts that will be able to drive the 10W load.

The PCB is custom designed, but you can see that it was shaped to match the wall wort’s original board. To the right is the original 500mA transformer. The low-voltage side uses an LM393 because of its dual-comparators. This provides feedback for both current and voltage and is a perfect compliment for the TOP242. We haven’t seen that part before, but [Mincior] says that it’s nice for this application as it has safety features that lock down the chip if power or temperature are above spec. Once the replacement is nestled inside of the plastic case it looks stock and makes sure that your custom LED fixtures will stand the test of time safely.

Hackaday Links: February 9th, 2013

February 9, 2013 by Mike Szczys 6 Comments

Hobby electronics from 1982

[Lennart] came across one of his projects from several decades ago. It’s a twinkling star which blinks LEDs at different rates using some 7400 logic chips and RC timers.

Solder fume extractor

We’re still blowing the solder fumes away from us using our mouth, but this might inspire us to do otherwise. It’s a large PC fan mounted on a lamp goose neck. It clamps to the bench and is quite easy to position.

Ultrasonic liquid level measurement

Wanting a way to measure the liquid in these tanks without submerging a sensor, [JO3RI] turned to an Arduino and an ultrasonic rangefinder. His method even allows the level to be graphed as shown in his Instructible about the project.

Adding an ‘On’ light to save batteries

Dumpster diving yielded this electronic drum machine for [MS3FGX’s] daughter to play with. The problem is that pushing any of the buttons turns it on, it doesn’t have an auto-off, and there’s no way to know when it’s on. This is unacceptable since it runs on 5 AA batteries. His quick fix adds this green On LED. We wonder if he’ll improve upon this and add an auto-off feature?

CMOS Binary Clock

This is a portion of the guts of [Dennis’] CMOS Binary Clock project from the early 2000’s. He even built a nice case with a window for the LEDs which you can see are mounted perpendicular to the protoboard.

NASA Inspired Circadian Rhythm Lights

February 8, 2013 by Mike Szczys 10 Comments

circadian-rhythm-light-rig

After reading about an initiative between NASA and Boeing to develop lights for the International Space Station [Rasathus] decided to give it a go at building his own. The project uses RGB pixels to build a circadian rhythm light installation. Without the normal rise and fall of the sun the sleep wake schedule for the astronauts can be pretty rough. This uses color and intensity of light in a well-defined schedule to help alleviate that. [Rasathus] is trying to bring his project in well under the $11.1 million mark which was established for the ISS.

The light modules he’s using are from a strand of LEDs from Adafruit. Each is driven by a WS2801 controller, a common driver used for easy and complicated projects like this huge ball of light which our own [Jesse Congdon] tackled. The board above is the start of an adapter board for interfacing with the Raspberry Pi GPIO header. [Rasathus] wanted to make certain he didn’t fry the control electronics so he built some protection into this adapter. The control software is covered in the second portion of the write up. We’ve embedded the video from that post after the break.

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Stellaris Launchpad Shield Shows Good Fabrication Technique

February 4, 2013 by Mike Szczys 6 Comments

launchpad-shield-with-great-fabrication

Here’s an LED and Button shield for the Stellaris Launchpad (translated) which you can fabricate at home. It gives you access to a 5×5 matrix of LEDs, and adds four more buttons. In order to cut down on the number of I/O pins required to operate the lights [Cosimo] is using the concept of Charlieplexing. This lets him get away with just six driver pins and four button pins.

It’s not just the finished product that interests us here. The fabrication itself is worth clicking through to his project post. What initially caught our eye is the use of Kapton tape as an insulator so that clipped off LEDs could be used as jumpers flat against the top side of the board before populating the LEDs themselves. After those are soldered in place he masks them off, as well as the button footprints, and uses spray paint to protect the top side of the board. The final look is more polished than most at-home project boards.

Elemental Display Is Also A LED Wall

February 4, 2013 by Brian Benchoff 14 Comments

elements

[Dan] is an element collector, someone who gets his socks knocked off by bismuth crystals and the orange vapor of bromine. Of course every element collector needs a proper display case, and since the periodic table table idea is cliché, [Dan] decided to build an elemental display that’s also a really awesome LED wall.

The build started off as most do with a few sheets of plywood and 120 acrylic shelves for each item in [Dan]’s collection. The real magic happened when [Dan]’s buddy [Bill] was called in to make the display a little more interesting.

Behind each acrylic shelf is a three-LED section of a LED strip, each part of the periodic table having a different color. The 120 individual shelving units are broken down into 16-shelf groups, each driven by a custom LED driver board. These driver boards are connected to a master Arduino with phone cables and make wonderful use of a very neat TCL5940 Arduino library.

The elemental display has a few options; all-on, twinkling, an Apple ‘breathing’ mode, and a graphic eq, as shown in the video after the break.

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