noob has question on direct driving leds...

[celtickeeper1]

im building my first saber and am trying to direct drive a red lux 3 off of 2 aa batteries. i know in theory the luxeon wants 2.95v so 2 aa's make 3v and it should be golden. problem is led looks dim to me so i hooked up a multimeter with the led powered and it only reads 2.5v. im a complete electronics/wiring noob... but am i doing something wrong? ha, i dont even wanna mention the voltage/brightness problems when i hooked it up to the cheap hasbro soundboard, it need 6v to it just to get 2.75v out with the led in the circuit but the soundboard starting smelling burney any thoughts?

[Darth Morbius]

1. Check you connections.

2. Have you checked the resistance of the connections in your switch?

3. What gauge of wire are you using?

4. Check to make sure your batteries are fresh.

[Novastar]

When I direct-drive a Lux III red with a 2AA pack:

* I read ~3.3v from the fresh cells
* I read ~3.0v from the cells when they are under load (in this case, the Luxeon III)

2.5v = when Morbius said... #4.

If you put two packs together, you can double the runtime... if you wire it correctly.

[JediKnightBJ]

Are you using rechargeable AA's?

If so then your multimeter is reading correct, they are only 1.2v's per cell. With a full charge, could be putting up that 2.6v's.

[celtickeeper1]

1. Check you connections.

2. Have you checked the resistance of the connections in your switch?

3. What gauge of wire are you using?

4. Check to make sure your batteries are fresh.

thanks for the replies.

1. just battery pack wired to lux... wires off battery pack read ~3.2v without lux, ~2.5v "under load" from lux (thanks nova for the terminology ) tried both luxeons i had... one soldered up w wires and connected to heatsink, one bare... identical results.

2. no switch yet, just testing (unless you count when i hooked up the hasbro board, in which case it was putting out .1-.2v less than batteries alone w no lux hooked up so that seems normal)

3. whatever comes attached to the 2aa battery holder ultra uses, my guess is 18-20 maybe

4. brand new batteries, not expensive ones but they read ~3.2v off the pack so that should be ok.

any chance the resistance is in the luxeons? it seems like im doing everything right... i tried both i have and they both do the exact same thing. they are from the same batch as they were connected when i recieved them fom the store (tcss).

[Lord Dottore Matto]

There is an old saying in the saber community, "This thread is useless without pictures..."

In other words, you "think" you have it wired correctly, but do you really? Take some pix of your set-up and post them here. Then we will be able to actually help you!

[celtickeeper1]

There is an old saying in the saber community, "This thread is useless without pictures..."

In other words, you "think" you have it wired correctly, but do you really? Take some pix of your set-up and post them here. Then we will be able to actually help you!

pretty standard i thought... maybe not?

[celtickeeper1]

bump for added pics, thought an edit would do it but i guess not...

[Darth_DevilGuy]

<that pack looks like it's running in series rather than parallel, I may be thinking backwards but I think that that pack would run it with double the MAH rather than the voltage/amperage...>

scratch that I'm backwards, series adds voltage, parallel adds MAH, I can't think of why that wouldn't work tbh.

[Vallen Kel-Romarr]

Can you post a clearer close-up shot of the star/connections/top of the heatsink?

Thanks!