LED Constant current array help

Thread Starter


Joined Sep 14, 2011

I know nearly nothing about electronics but I'm on a mission to build an LED array.

Here's my a list of my equipment and following that will be an explanation of how I plan to assemble it.

1x 670mA 36W Power Constant Current Source LED Driver (input: 85~265V output: DC 28-45V)

2x 9Vf Warm White LUXEON Tristar LED

1x 6.3Vf Red LUXEON Tristar LED

1x 6.6Vf Deep Red LUXEON Tristar LED

1x 9.3Vf Blue LUXEON Tristar LED

Power supply will be wired the plugged into the wall. Power supplies output will be connected to all LEDs in series for a total of 40.2Vf (well under the 45V max).

How do these power supplies work?
I understand the current is CONSTANT as the name implies. If the voltage variable depending what kind of load you put on the circuit?

I'll also heat sink everything and strap a fan on to keep things cool.

Will this work?
Is my thinking right?


Joined Sep 8, 2011
I'm pretty sure it will =)

Yes the current is constant and the voltage is variable because the led's voltage drop isn't constant.


Joined Mar 24, 2008
You only need one or the other regulator, not both.

I would use something similar to this...

It has a reasonably low parts count. However, it will get very hot, depending. You will need adaquate heatsinking, and possibly a fan. This is just an illustration, you would need to modify this design to your needs.

A SMPS constant current source will run much, much cooler and be a lot more efficiently (the two are related). Google buck puck. We have several untested experimental designs you could try out.


Joined Sep 9, 2010
Will this work?
It looks OK to me: The LEDs can tolerate a bit more current than that supply produces, the total Vf is OK as you've noted. All is good.

The price of that supply is tough to beat unless you've got parts already in hand and enjoy the DIY approach.

The thing I'd think about before turning it on is heat dissipation. Make sure those LEDs are kept cool at that current level. The current spec for the LED is probably for some ideal world that is really tough to achieve, and your supply is getting close to that spec. So better give it some thought.


Joined Oct 15, 2009
Before you turn them on....Heat sink, heat sink, heat sink.
Let me add a couple more to drive the point home.. Heat sink, heat sink, heat sink, heat sink, heat, sink...and fan (air movement makes all the difference in the world)

Thread Starter


Joined Sep 14, 2011
You guys are UNBELIEVABLE!
I'm going to post a new thread on this but does anyone have thoughts on where to buy LEDs with specific wavelengths?

I've been searching around online and there's various sources but I feel that the Luxeon website is the best option. I've read their LEDs are good, and the website seems to imply that the REBEL series are the most up to date versions of their LEDs.

DealExtreme.com has LEDs for cheaper but I have no idea what the wavelengths are and I have no IDEA in the world how to figure out which LED they're selling exactly based on the BIN/item code they may/may not have provided and then matching that code to the naming guide baffles me.

I've looked through MOUSER.com and NEWARK.com but I don't want to end up buying LEDs that are old models and less efficient.

THANKS again you guys are all over this stuff.

PS. Bill, I can read a basic circuit diagram but the one you provided confuses me. If everyone else is saying what I have planned will work I think I'll just go with that. BUT I'm always keen to learn and improve on my design.