Help with my first LED Saber? (Resistors give me headaches)

[FaithTruthWisdom]

Greetings fellow saber enthusiasts! I'm looking to dive head first into building my first custom saber. I've poured over these forums, as well as the YouTube channel; watching countless tutorials and drawing up (crude) diagrams to put together the guts of the beautiful Sith Relic I've been designing in my mind.

One hiccup: I know bubkiss about electronics. Now, I can use the different formulas to calculate watts and ohms just fine, and I know there's some wiggle room when selecting your resistors. But just to be safe, I figured I'd run it by you fine people before I spend a whole lot of money to (potentially) create a big puff of smoke.

The components I plan to use:
Nano Biscotte V3
Red/Red/White Cree XP-E2 CopperNova
Panasonic 18650 3.7v Battery w/ recharge port
12mm Red Ring AV switch.
2x Red Accent LEDs (for crystal chamber, 2.0-2.2v, 20mA)


As for the LED in the 12mm switch, as well as the two accent LEDs: I plan on running these in parallel off of the 3.3V Power Indicator pad featured on the NBv3. Am I correct in assuming that the 20mA DynaOhm resistor would be adequate to run these 3 LEDs safely?

Second question: If I've done my math right (and unlike Tony Stark, I may have botched this), I'll need a 0.38W, 3.17ohm resistor for the twin Reds, and a 0.55W, 0.55ohm for the White. Did I do the math right? And if so, which resistors should I use?

I bow to your superior knowledge, and thanks in advance!

[darth_chasm]

It's usually recommended that you use a resistor for each led. I've never used the dynaohm so I won't comment on that. The calculation for your main reds seems high. If I remember correctly, they need 1.2 ohm 1 watt resistors.

[FaithTruthWisdom]

How I missed the LED calculator (http://led.linear1.org/1led.wiz), I'll never know. According to it, I should run 1.2ohm, 1.2+w on the reds, 1ohm, 2+w on the white, and 68ohm, 1/8+w for the switch/accents. So far I've based my wiring on the tutorials on the TCSS YouTube channel, which recently showcased a build utilizing the NBv3 and a Tri-Rebel, where he spliced both positives on the twin blues to a single resistor.

Going by the above-mentioned calculator, it mentions to use "or higher" on the watt readings. How high is too high?

Based on the Dynaohm description, its a variable-voltage resistor which provides a constant flow of 20mA.

[darth_chasm]

The calculators are notorious for rounding up a bit too high sometimes. Especially under 1 ohm. For the white, being the FOC led, you could probably get away with the .5 ohm resistor in the store.

Wattage is just how much heat the resistor can dissipate. Going over won't have any adverse effects except eating up more physical space. A 5 watt resistor is considerably bigger than a 1 watt and so on.

[Greenie]

Agreed. My lastest saber, the reveal, uses a tri Cree R/R/W. DC's numbers are spot on.
I have used the dynaohm for an AV switch. It does fine but it ain't small and you want three. You may wanna do the calcs for accents. The correct resistors may well be smaller than the dynaohm.