Bringing state-of-the-art LED Lighting to Hobbyists
The goal of the Light Brick 5 is to design a modular, ultrabright system suitable for any hobbyist to build their own LED lighting system based on any control scheme they like, for cheap, and without having to know power electronics or fabricate their own PCB. This should allow enough flexibility for someone to control the system using anything from an arduino board, to a parallel port on a computer, to an entirely custom designed system.
Warning: If you choose to assemble your own light fixture, your warranty will be limited. The below plans are provided "as-is", and no warranty express or implied is offered for fixtures not constructed in entirety by saikoLED, LLC. If the components sold by saikoLED and assembled by customer are damaged due to improper assembly, the customer is responsible for the repairs.
If you require a warranty beyond our standard 14-day return policy for undamaged goods, please purchase a complete Saiko5 fixture, which is assembled entirely by our staff. We can not be responsible for damage caused to our products due to customer assembly whether done according to the below plans or not.
The basic design is fundamentally very similar to the Ultraluminous Illuminator developed by Brian Neltner in 2007, except with the power supply integrated into the LED board, and without a controller of any kind. Instead, the Light Brick 5 is designed to be controlled through a 5 wire interface. 24VDC is applied to the positive terminal, GND is applied to the ground wire, and then three control wires are used to turn on each color of LED as desired using TTL level signals.
The Light Brick uses the same design for the power circuitry as the Ultraluminous Illuminator. A National Semiconductor LM3404 is used as the basis of the power circuitry with a buck converter in order to provide a constant 700mA regardles of input power voltage (18-36VDC). The board has three colors of LED -- red, green, and royal blue Rebel Luxeons from Philips Lumiled, with four of each color LED per board. Each control pin is pulled down to ground so that the device defaults to "off", and connected to a five pin connector for external control.
As you can see, the schematics are fairly simple, limiting the ways the device can fail. The LED board layout (below) is designed so that the royal blue and red LEDs are on opposite sides of the pattern with four green LEDs in the middle. This layout allows for the placement of every electrical trace on the PCB in a single layer, and by using only SMT components, the back of the board is entirely bare of electrical contacts.
The advantages of laying out the board with all the traces in a single layer are significant. The biggest benefit is that because the Rebel LEDs are electrically isolated at their heat sink, a single, continuous heat sink on the back of the board can very easily cool the LEDs. Secondarily, without electrically connected traces on the back of the board, there is no risk of short circuiting through the aluminum case the board is bolted into, eliminating the need for an electrically insulating but thermally conductive adhesive on the bottom of the board. The bottom of the board is shown below, where every visible hole (via) is grounded and connected to the LED heat sinks.
Next, more input protection is added to protect against user error in connecting the device. Between a fuse, eight input protection resistors, three zener diodes on the digital lines, a large 5W zener diode on the power input line, and a full bridge rectifier, it should be possible for the user to plug the wires in backwards, connect line voltage to the device briefly, have a noisy signal line, or other usually nasty errors without completely destroying the board. Of course, there will be a somewhat difficult SMT fuse to desolder and replace to repair the board in the event of catastrophic failure, but that's a good sight better than replacing all of the tiny and expensive chips!
For initial prototyping, a Weller hot air rework station was used to make sure that the LEDs were soldered without any residual stresses that could make the joints come loose over thermal cycling. This is done by first putting down a small amount of solder paste on the thermal pad and the two pins, and then heating the entire board up using a two-output air nozzle. A better small scale production method is to use a solder stencil along with a hot plate to reflow the entire board simultaneously, and this is what is actually used for our production. For an example of how to carry out hot plate reflow soldering, see the Extreme Surface Mount Soldering Instructable.
This also serves the purpose of "replacing" the LEDs into their correct seating on the board as surface tension from the melted solder pulls the part into position. It's actually a fascinating thing to watch as the LEDs "jump" into their correct, centered position (this is important for making them correctly placed for the optics!). The first step to this method of soldering is to place solder paste onto the board, either using a syringe, or a stencil.
Next, I placed all of the LEDs and other components using tweezers.
Finally, it's time to heat the board on a hotplate in order to reflow and replace the components.
The last step in board assembly is then to attach the optics -- in this case OPC1 style optics from Dialight. They're great! There are three tabs to guide it into the correct position (which is good so long as your LEDs are centered properly from reflow soldering them), and they are adhesively backed so that they stay in place. They also look quite snazzy, in my opinion. A very attractive board!
Now to power it on, I attach 20VDC or so across power and ground, and then touch the control pins with 5VDC (current limited, just in case on the digital lines!). Below you can see me manually touching the control pins for the red, green, and blue channels one at a time.
The final device puts out around 1000 lumens of light, assuming 80% optical efficiency (i.e. 20% of the light is lost to the optics and LED inefficiencies). These particular optics focus the beam down to a 7 degree cone, and even from this wide angle that the photos are taken from (around 45 degrees), it's pretty obvious that you wouldn't want to look straight into this one! I turned it on full white, and was able to basically replace the light output of the 60W incandescent overhead light in my room!
The cases are designed to make use of the simplest possible design while still being attractive and functional. The design utilizes a 1/4" back plate made of aluminum and anodized for a primary heat sink. This board has four holes for 6-32 holes which are used to attach the circuit board rigidly, and has a hole in the center of an appropriate size to fit the ferrule from a 1/4" Moffatt Flex Arm. It extends past the edges of the 5" diameter circuit board to the diameter of a standard schedule 40 5" aluminum pipe, with four grooves.
After tightening a nut to hold the flex arm to the aluminum back plate, five wires are threaded through the flex arm to carry power and control signals:
This plate with board attached now has four grooves in the sides, big enough for a #6-32 screw. These allow the back plate to be fixed directly onto a 5 inch schedule 40 aluminum pipe about three inches long. The pipe is anodized as well, and has #6-32 threaded holes placed at 0, 90, 180, and 270 degrees on both sides of the pipe to allow easy attachment of the back plate to the pipe.
Finally, an acrylic lasercut cover is placed on the top, cut to perfectly fit the aluminum pipe and with four identical grooves to the base plate in it so that the acrylic piece can be attached to the end of the pipe as well. This protects the board fairly well from the environment, and allowed the lights to survive even the harsh environment of Burning Man. This is not waterproof, but it does help a great deal against dust and dropping, as well as offering limited protection from moisture.
The Light Brick 5 Digikey Bill of Materials can be downloaded here. This document can be uploaded at Digikey in order to easily get all of the components required for assembling a Light Shield 7 of your own. This Bill of Materials does not include the Rebel Luxeon LEDs from Philips Lumileds which can be ordered through Future Lighting Solutions.
What we'd be really excited to see come of this is to be able to sell these systems on a hobbyist website like Sparkfun Electronics. They also sell the Arduino system, which has many sensor modules. Imagine how awesome it would be to have this connected up to, I don't know, a geiger counter and a microphone so you can have it flash red when it detects radiation, and then flash blue once it hears screams. Or maybe just have it flash red and blue on a curtain if a video camera detects motion.
Okay, maybe those are stupid ideas. But that's sort of the point. As a designer, I may be good at designing hardware, or perhaps someone else is good at writing software, but any one person can only have so many ideas on their own. We'd be thrilled to see people buy these, come up with awesome new uses for them by integrating them into their own projects, and then publish the code so that we can build up our cumulative open-source expertise. I'd love to see the day where there are a dozen or even a hundred individual hobbyists who've done crazy cool stuff with this light (or others like it) and published it online to inspire the rest of us! So, in that spirit, please let us know if you are psyched about getting involved in participating! We have lots of ideas, but I'm sure many of you have way cooler ones than me =)
You can also check out media and information on the places where this system has been used as a part of the Saiko5 WiFi LED Light Fixture in the Installations and Applications section. So far, it's been made to work with Arduino, the amazing Leaf Labs Maple Board, a higher processing power hobbyist board designed to be pin compatible with the Arduino, and the folks at Leaf Labs managed to make their Maple Board as well as the Arduino control the Saiko5 WiFi LED Light Fixture using an entirely wireless interface by using the async_labs WiShield as a basis and then improving stability. Check out the Light Shield and Firmware for more information about those code improvements, as well as our custom board for WiFi and power control.
Brian Neltner, R.J. Ryan, and Perry Hung also wrote software that allows a user to take advantage of the aubio library, a sweet sound analysis suite usable in C, Python, PureData, and other languages for analyzing realtime or pre-recorded music and extracting relevant features from the sound such as the beats, transients, and other cool stuff! Check out the Software page for more information about the control software.
