What type of resistor do I need?

Mark_Paulus

Enlightened
Joined
Aug 13, 2003
Messages
224
Location
Colorado Springs, CO, USA
Hello,

I have a Fraen Tri-Star optic, (3) Luxeon III that I will use with the optic, a Craftsman 2D Tool light that will house this setup (The TriStar optic fits right in with just a minimal amount of sanding on the outer lip to fit the supplied rubber gasket.).

Now, I plan on feeding this beast with either a 2D Li-ion replacement pack (rated at ~2200 mah / 8.2V), or (2) 18650/17670 (rated at about 1400 mah / 8.2V).

I would like to drive these LEDs at 1000mA ea. According to the Lumileds calculator, I need either a 4.7 ohm / 5W, or a 5.6 ohm / 5W resistor, depending upon whether I decide to run at 8.2V, or calculate for the possibility of (3) CR-123 / 9V, using a Vf of 3.90. Oh, yeah, these calcs are based upon running the 3 stars in parallel.

So, what's the problem, you ask?

I would like to know if I need to use 5W resistors, or can I use other resistors, such as 1W or 3W? Also, would I be better off using 3 resistors, one per star, or can I use 1 resistor, and then split from the resistor and go parallel to the stars?

Thanks for any/all inputs.
 
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