Posted on Sunday, 13th May 2007 by Auw Jimmy
I’ve finished my Luxeon III project. It contains two Luxeon III Star (Lambertian). I design a simple voltage and current regulator based on two National Semiconductor LM317. You can adjust the current and the voltage by using few resistor or potentiometer. I will discuss about the driver on separate post (later). Now, just enjoy the project showcase first
The picture above shows my project. As you can see, I use two LM317. The first one is to regulate the current, the second one is to regulate the voltage. I use two switches to set the current. All switches off means 200 mA, one switch on means 400 mA, and two switches on means 600 mA. Actually I should provide switches to set the 800 and 1000 mA. Perhaps later. The resistors used for regulating the current should be minimum 2 Watts (I use 5 Watts).
I mount the Luxeon on separate heatsink (remember: Luxeon III backplate is not insulated! So please don’t mount more than one Luxeon III on same heatsink. Except if you will use epoxy compound that will transfer the heat, but not the electricity). This Luxeon may need adequate heatsink if you will drive it with high current (up to 80 Lumens @ 1000 mA).
Top view from my Luxeon driver. Adequate heatsink is required for the LM317. Quite hot after 10-15 minutes of operation. Don’t forget to use thick enough cables, since you will driver over 500 mA of current.
Another view from the front side. Not a really good layout from me I mount all the resistor and diode in standing position to save the space.
Another view from the back side. I use some cable ties to tight up the resistor to the switches. Again, not really a good design.
I mount the Luxeon on the heatsink with some thermal paste. Then, I glue them up with some epoxy to make sure that the Luxeon will be tighted firmly to the heatsink.
Luxeon III on action. All switches are turned off, means the current is rated at 200 mA.
Luxeon III on action. One switch is turned on and one turned off, means the current is rated at 400 mA.
Luxeon III on action. All switches are turned on, means the current is rated at 600 mA.
The Luxeon on typical room lighting. On the photo, I set the current at 200 mA (both switches are off). Quite bright, eh?
I plug the 15 degree lens to each Luxeon. Hmm… this time the beam is more focused. Good as a flash light!
I open up the lenses and feed the Luxeon with 600 mA. Man, I can’t see the Luxeon right now. Simply too bright!
My conclusion is: This is an excellent LED. Very bright LED. Use 2 or 4 at 600 mA and you are ready to blind your friend’s eyes. The minor problem is the backplate of Luxeon III is not insulated. It means that you have to use special epoxy that will transfer the heat, but not the electrically conductive or better use separate heatsink. The current and voltage regulator are also cheap to design (less than $5). For you who want to make it simple, you can search for special ready to use Luxeon driver (buck or boost version, around $20). But I prefer my own design