Designing A Controllable RGB LED Driver Board

March 30, 2011 by Mike Szczys 16 Comments

[Paul] wrote in to tell us about this LED driver board he’s been working on with a few friends. The collaborators had been unhappy with the Lumens per Watt ratings (or lack of a rating) on low powered LEDs and set out to find a better solution. They picked up the beefy ASMT-MT00 which houses all three diodes in one package, with all the pins on one side of the surface mount package, a heat dissipating tab on the other side, and pushed 30 Lumens per Watt. With that in hand they set out to design a host board for the blindingly bright light.

The board includes a heat sink on the underside. To drive the LEDs [Paul] sourced an LM3407 constant current driver. The manufacture recommends using one of these chips for each of the colors in the LED package. [Paul] built a circuit that allows him to route power around each LED, making the system work with just one low-side driver. From there, an ATtiny2313 provides addressable control via the RS485 protocol. Screw terminals on either end of the PCB allow this to be chained along with other modules, and they’ve already worked out a basic PureData program that will be able to address multiple boards once they finish manufacturing them.

Super Pong Table Doubles The Fun

March 29, 2011 by Mike Nathan 8 Comments

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While Pong has traditionally been a game played between two individuals, Instructables user [Brad] has put together a variation that doubles the fun. His Pong coffee table has the ability to support up to four users at once, and makes for quite the living room centerpiece.

The table is made from sheets of MDF and incorporates a grid of 900 LEDs, all controlled by a PIC18 micro controller. The MCU is installed on a control board he designed, along with the other additional bits required to drive the LED array. A set of old Atari paddle controllers were disassembled and installed around the table, making this a true retro Pong experience.

As you can see in the video, the action is pretty frantic. It’s hard to tell who is winning until the game is over, but [Brad] says that a scoreboard will come in a future revision.

4-way Pong is a really cool idea! ~~, but it looks like there are no open source schematics or code for the control board. We’re hoping someone sees this project and puts together a version for all to use, free of charge.~~

We were mistaken about the status of this project in relation to whether or not it was open source. [Brad] wrote to us letting us know that his code was not originally included with the Instructable as a result of a late night omission. As always, his projects are open source, and you can now download all of the source code and schematics at the page linked above (and in the first step of the Instructable, no less). Mea culpas all around, thanks for the update, [Brad]!

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LED Floor Lamp Really Ties The Room Together

March 28, 2011 by Mike Nathan 12 Comments

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Instructables user [lincomatic] was doing some home decorating and was trying to find something that would really tie the room together. He decided against adding a nice rug, a light fixture is what he was after. Rather than settle on a simple lamp for the corner of the room, he constructed an 8×8 RGB LED fixture he calls the Lampduino.

He constructed the 8×8 grid using some leftover cardboard packaging, then got to work wiring up the LED strands. In a rather unorthodox move, he decided to wire wrap the LED leads instead of soldering them. Once the LEDs were in place, he wired everything up to his Colorduino, an Arduino derivative specially made for driving large quantities of LEDs. A thin sheet of drafting film was placed on both sides of the board, then it was mounted on a stand for display.

His Daft Punk-esque lamp can be programmed to display just about anything from color patterns to video game sprites, and it can also be timed to music if desired. We think it looks great, and could make for a nice wall hanging if he ever got sick of the stand. While the wire wrap technique sounds like it sped up the development of this project significantly, we would be interested in hearing how it holds up after a few months of use.

Check out the trio of videos embedded below to see the Lampduino in action.

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Low-voltage Wind Turbine Lighting

March 24, 2011 by Mike Nathan 30 Comments

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Instructables user [Dustyn] recently constructed a wind-based lantern to provide a bit of free, renewable light in urban settings. The project is based around a vertical-axis wind turbine, which she says are better suited to these environments since wind often comes from all different directions. Despite their lower efficiency compared their horizontal-axis brethren, this style of turbine seems to fit her needs quite well.

She provided a complete bill of materials, down to the last screw and washer you would need to replicate her work. The wind sails were constructed from thin aluminum flashing, and inserted between two acrylic sheets. These were then mounted to the central aluminum shaft of the turbine, which drives the stepper motor built into the base.

The current from the stepper motor is rectified and run through a pair of capacitors before being used to light the attached LED. This allows the bipolar motor to provide current regardless of the direction the turbine is turning, and the caps smooth things out so that the LEDs don’t flicker wildly under varying wind conditions. The turbine is not going to light up a full city block, but it is definitely a nice alternative to sun jars.

Stick around to see a video of the turbine mechanism in action.

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Laptop Touchpad-based LED Lighting Control

March 24, 2011 by Mike Nathan 5 Comments

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[Dave] needed some extra light above his desk/workbench area and decided to wire up some RGB LED light strips to brighten the place up a bit. He wasn’t content with using a standard switch to toggle them on and off, and after some brainstorming, he decided to build a capacitive touch circuit using a pair of copper tubes mounted in a project box. Just as he was putting the finishing touches on his switch, he saw a project online where a Synaptics touchpad was used in conjunction with an Arduino for lighting control. The copper tube switch was pitched, and he got busy working with his Arduino.

When connected to an Arduino, the touchpads can be used in two modes – relative and absolute. Relative mode is familiar to most people because it is used to guide the mouse cursor around on a laptop’s screen. Absolute mode however, relays coordinate information back to the Arduino, allowing the user to map specific areas of the pad to specific functions. [Dave] enabled his touchpad to use absolute mode, and mapped a handful of different functions on the Arduino. He can now fade his lights on and off or light the room on a timer, as well as use a sliding function to tweak the LEDs’ brightness.

It’s a neat, yet simple hack and a great way to repurpose old laptop touchpads.

Continue reading for a quick demo video he put together, and swing by his site if you want to take a look at the source code he used to get this working.

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POV Business Card Is Guaranteed To Get You Noticed

March 21, 2011 by Mike Nathan 17 Comments

Some say that handing out business cards is an antiquated practice due to the ubiquity of smart phones which can be used to trade or record contact information in mere moments. Instructables user [sponges] however, doesn’t agree and is pushing a “business card renaissance” of sorts with his POV business card.

Hand-built in his basement, the cards feature a handful of SMD LEDs that display his name, followed by his phone number when waved back and forth. Constructed to be nearly the same size as a standard business card, his verison uses a PIC to manage the display as well as a tilt sensor to monitor the card’s motion. His walkthrough is quite thorough, and includes tutorials for each of the steps required to build the card. He discusses constructing your own etching tank, converting a laminator for PCB transfer purposes, building a solder reflow oven controller, as well as hacking an aquarium pump for use as a vacuum-powered pick and place.

The end result is a sharp looking business card that ensures you won’t forget meeting him. Keep reading to see a video of the card in action.

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Third Time’s A Charm – 512 LED Cube Kicks It Up A Notch With RGB LEDs

March 20, 2011 by Mike Nathan 25 Comments

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In the comments section of our 512-LED cube post from the other day, several people suggested that to take the project up a notch, building a similar cube using RGB LEDS was the next logical step. It seems that Hack-a-Day reader [vespine] was way ahead of the curve, as he sent us the build details of his 8x8x8 RGB cube shortly after the other story was published.

His cube, which was finished earlier this year, uses 512 10mm RGB LEDs, arranged on top of a simple elevated stand. The stand conceals all of the circuitry he uses to control the cube, the centerpiece of which is a PIC32 MCU. A dozen TLC5940 16-channel PWM drivers are used alongside the PIC in order to adjust the color output of the LEDs, each of which can be addressed and colored individually.

The end result is just about as amazing as you would imagine. He has created several quick demonstration animations, which you can view in the video below. Be sure to stop by his site to see all of his build details – there’s quite a lot there.

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