Resistor Question

[Yorginsnarff]

I see. So it'd just be better to wire two .48 ohm 1/2W resistors on each respective wire, THEN splice then off to the board.

Yeah Madcow's method seems a bit more professional. I'm still a youngling after all ^_^

[Bark]

Agreeing with FJK, one resistor on a splice for two LEDs in parallel is problematic for this reason. If there is a slight difference in the LED dies, from the manufacturing for example, they won't draw current equally. One will draw more than the other. If it draws so much that it pops, all of the current then goes through the remaining LED die. Since that's twice the current it can handle, it will shortly pop too.

Some of us here, like FJK and me, think it's just safer to dedicate a resistor for each LED die. That's the only way to make sure the LED die isn't drawing more than what you intend.

However, I personally don't like to splice off the board if I can just splice wire closer to where the junction physically has to be. For example, one wire on the board going to the splice near the heat sink. If you put the resistors on the positive side, you can still do a Madcow setup for the negative side wiring if you want to save real estate and have only one negative wire for both LED dies.

[Yorginsnarff]

ooh, so I found a .22 ohm, 2W resistor. Can I use these for the greens, since I calculated 0.12 would be the resistance value and still not blow the LED? (The 2 watts should take care of any heat problems I have)

Equation for the greens: ( 3.7-3.58 ) = 0.12/1A = 0.12 ohms is Resistance <-- Rounding up to .22 ohm 2 watt resistor? Is this ok?

Equation for the white: ( 3.7-3.15 ) = 0.55/1A = 0.55 ohms is Resistance <-- I'm rounding this up to 1 ohm 2 watt resistor

[Yorginsnarff]

nvm I remembered that resistors are always safer the more you go up. My brain had a stupid moment lawl.