You're right. It doesn't regulate current, it's got "A high-power LED direct drive (no current regulator)". Right from the manual.
Still, I've used the Drive setting with normal 3w LEDs without resistors and without problems, one would think in theory that the Tri-Rebels (for exampl) would work the same.
The resistors aren't bad once you get it figured out. This thing here is your friend.Originally Posted by Yoshi-Taka
http://led.linear1.org/1led.wiz
Don't ask me how to get all of the values, I forget this stuff the minute I dont need it anymore and would have to try and re-learn it all just to answer the question. But that resistor calculator can give you what you need. Then you can go to Mouser.com or someplace that sells 10000 different resistors and stock up very easy for not a lot of money. For that setup I did, I knew that I needed 1watt resistors for my setup and anywhere in the 1ohm to 5ohm range. I got like two of several different sizes and swapped them around until I had the right combination. I've done the same with another LED with green & blue dies to get kind of cyan color. Don't let the resistors sway you. Its kind of a pain, but once you've read up on it some it will come together.
It would depend on the limits for the individual dies on the Tri-rebels. The DX RGB's I worked with cannot take as much as a single die 3W led and that all I have any experience with other than the Ledengin (which was through the PC and didn't require a resistor)
Yeah I use the calculator for accent leds all the time. But I figure if I don't have to use a resistor, I don't want to, you know? If my theorizing is incorrect and I have to use resistors, then I will.
But let's say I'm using a GGW Tri-Rebel. In theory, I should be able to wiring the G and G in parallel, and use the Drive to maintain them both, yes? I mean, they're basically the same G LED just being use together and in theory the Drive setting would be the same for both, therefore it would be able to maintain them both without overdriving them. That's my thinking; I hope I'm right but if I'm wrong, oh well and I'll use resistors. But better to be safe and ask, right?
Last edited by Yoshi-Taka; 01-28-2013 at 09:03 PM.
The "drive" setting adjusts the voltage, but not the current. It's used to set the output voltage to the nominal LED voltage for when the latter is very close to your battery voltage.
In this case, you would set the NB output voltage to equal the highest forward voltage (blue) of the parallel LEDs. Then calculate the required resistor for the lower voltage LED (red) based on the new output voltage instead of the battery voltage. That saves you one, but not two resistors, because the nominal LED voltages are different.
Is this a requirement, or could I leave the default settings as they are?
EDIT: Nevermind, I just re-read the post and answered my own question.
Going back to Silver Serpent's answer to my original post, where would I place the resistor? Would it go on one of the arms of the Y, or the tail?
Last edited by Maleficia; 01-29-2013 at 10:37 AM.
One of the arms, specifically, the arm that has the LED whose power you're trying to control (i.e.: the red one).
I thought I needed a resistor on each LED based on previous comments. Man, this is confusing.
If you set "drive 940" in the config file to bring the voltage down to what the blue LED wants, you do not need a resistor for that LED, just the red one. Otherwise, yes, you would need two resistors, different values, one in each branch.
Okay, that makes sense now. Thanks for clarifying!
So using the drive control method, I would just need to place a single resistor on one of the top "arms" of the Y splice on either the positive or negative leads of the red LED. Just for extra clarity, why wouldn't I want to put the resistor on the tail before the splice?
Posting Permissions
Reply With Quote
Bookmarks