resistor question

[Darth Money]

Does anyone know what size resistor is needed for a normal build with the red LED. I am new and this will be my first saber build I am also putting in a buck puck

[Racona Nova]

I don't know exactly, but I think I've read something that the red diode doesn't need to be resistored when you use a BuckPuck.
Maybe someone could confirm/correct that?

What I definitely know is that you have to do that when you're building a resistor-only setup.

[Darth Money]

hope so I just don't want to screw up my first build and eventually I will add sound to it at a later date

[TEmmett]

I've been looking up the same thing myself, trying to switch a couple of mine over to the li-po setup.
Here is what I have in mine without sound:

Blue Cree LED -> 2ohm 3w 5% resistor -> 4AAA battery holder. Resistor is on the ground wire, while the hot wire runs through the switch.
White LED -> Buckpuck -> Li-Po battery holder. I cannot find a resistor wired in this setup.

It would appear that the Buckpuck does not need a resistor; from what I've found its job is to regulate the output amperage anyway.
The data I can find on the Luxdrive LEDs that both of my sabers have suggest that a Red LED would need 2.3v @ 700ma.

The sabers I have with sound also have the Emerald driver, which does the voltage regulation in this case. I wouldn't think that would need to be different, but I can't say for sure.

[Darth Money]

that's a big help appreciate it I seen people complain that they burned out their LED but the pics didn't show a resistor or anything on it so I wanted to make sure that I learn from others mistake lol hard enough taking the wife into letting me spend what I have

[Darth Money]

what gauge wire is best to use when wiring them up?

[TEmmett]

The battery holders use 26Ga wire. My sabers have heavier wire between the resistor/switch and LED, but I wouldn't think it would need to be heavier than the power supply wiring. Also, there is a 700ma Buckpuck that would probably suit the Red LED better (the Blue, Green and White can take 1000ma). I hadn't looked at the one US sells separately, so I dunno if it's the 700 or 1000ma model.

[Kouri]

My understanding is US is using Cree LEDs on their sabers, even if they're mounted to a LuxDrive star. Those'll run 2.59v @ 1000mA.

But yeah, if you're using a buckpuck, circuit'll go something like this:

Battery positive > Latching switch > Buckpuck > LED > Battery Negative

You won't need a resistor with the buckpuck, but you should have 7v to run the puck. 4x AAA alkalines will only put out 6v, so you'll need two Trustfires wired in series or a custom Lithium pack that runs at 7.4v.

[TEmmett]

The numbers I listed came from a data sheet for the Cree XP-E http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/Data%20and%20Binning/XLampXPe.pdf
No listing for red @ 1000ma on it, so I assumed 700ma was the preferred amperage.

If it's an XP-E2, the numbers you listed match their data sheet http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/Data%20and%20Binning/XLampXPE2.pdf
Given that US only sells the 1000ma Buckpuck, I would imagine that it's this one; I've not seen anything on any of my LEDs that would confirm which version it is.

[Sarich Belmont]

You only need 5v to run a buckpuck, but I would actually recommend using a resistor and a single 18650 cell instead of AAA batteries. You'll get a much brighter saber that way.

[Kouri]

Huh, appears I mis-remembered the data sheet. You're right, 5v is the minimum input on a puck. Still, the max output voltage is 2.5v less than the input, and there are only so many LEDs that'll run on 2.5v, regardless of the mA. I'd say a safer minimum would be 6v, since a max of 3.5v should cover most single diodes.

I'll also vouch on the 18650 + resistor combo. Managed to wire up a Rebel Lime LED with a 1ohm 2w resistor, and that thing shines bright enough to light up a room.

[Darth Money]

cool thanks for all the info I will post when I get it all together I am just waiting on my parts to arrive

[Sarich Belmont]

Yeah, Buck Pucks aren't really as useful as they once were. I would still use them in a build that used 4 alkaline batteries, but anything else it's better to just use a single 18650+resistor. You don't get any more brightness from the extra voltage and the Puck actually limits the current being supplied if you are using, say, a Tri-LED, so it isn't useful at all there.