can one visually discern between different LEDS (without powering them)

[Avidgrant]

Thanks Silver Serpent!

[jbkuma]

The arrow stands for ground, which is the (-)

[Avidgrant]

OK- so i read Darth Chasm's tutorial, and if i understand it correctly- then i believe the results below are correct for working with NB3/3.7 Battery type of configuration... actually regardless of card- i believe the calculation is appropriate for 3.7V power source, but i would really appreciate it if someone could confirm so i don't go buy 50 bucks of resistors and commence blowing stuff up!
So i have a batch of many different Leds- all purchased through the store- a couple copper nova R/RB/G- and the rest are all luxeon. they consist of a combination of R/B/RB/G/W. So i did calculations for all these. Based on what i could discern from this site- the Cree reds and all cree colors- and all luxeon colors (other then red (red orange- deep red- etc)) can be run at 1000mA. Red luexon needs to be run at 700mA. So the calculations became simple (I think) as its all /1 and x1 (squared)... other then the red lux (If what i did is right).
So here is what i came up with
Luxeon
R- 1.3ohm/2.65w
B- .47ohm/.47w
RB- .5ohm/.5w
G- .47ohm/.47w
W- .6ohm/.6w
Cree
R- 1.11ohm/1.11w
G- .12ohm/.12w
RB- .29ohm//29w

I know you have mentioned you might not be able to find an exact match so you should get the next highest resistor, and i also understand from some of your posts that the higher ohm will affect the brightness- but i am a little less clear on what a higher W resister does.... does it affect battery life- drain- (is it better to get something larger here if you have the space??) efficiency ?

Thanks again for the help!

[rlobrecht]

so i don't go buy 50 bucks of resistors

Wow, that's a lot of resistors.

that the higher ohm will affect the brightness- but i am a little less clear on what a higher W resister does.... does it affect battery life- drain- (is it better to get something larger here if you have the space??) efficiency ?

The higher wattage resistors are able to disperse more current as heat. A larger one than necessary will just take up more space inside the hilt. It won't affect battery life.

[Avidgrant]

building blades for the kids, and me () and some extras to mess around with.

[Avidgrant]

can you tell i like to shop at Sams

[TheCheeker]

The wattage is just the maximum amount of heat the resistor can disperse. As long as the wattage is greater than what you calculated, you're good. It just means it can handle what you're throwing at it. Nothing else is affected.

The resistance, on the other hand, affects brightness. You want to get the resistance as close to your calculation as possible (without going under your calculated Ohms). When calculating resistance, you're calculating the answer to the question, "How much do I have to hold back in order to push a significant but safe amount of amps to my LED?". Since Ohm's Law tells us that current = voltage / resistance and knowing your battery pushes 3.7V (or whatever depending on your battery), as your resistance goes up, the current goes down. And the brightness of the LED goes down with it.

[Avidgrant]

ah..... ok- so- is it more beneficial - assuming there is room- to get the larger w resistor? Is there a point of diminishing returns- or where it gets to a point where it has a negative effect?
Also.... can anyone check my math and confirm on the wrong path.

[Silver Serpent]

If you meet the minimum calculated requirement for wattage, you're fine. Higher wattage will not improve performance, last longer, affect brightness, or anything else other than take up more room. The only reason to get a higher wattage resistor is if those are the only ones in stock at the time.