Question about resistors

**Darth Saevius** · 01-30-2013, 01:45 PM

I am building a PC 2.0 saber with a tri-rebel BBW. The saber will also have 2 accent LEDs, one green and one red. I will have two blue momentary switches, one ring and one dot.

I've read the pc 2.0 manual and I understood a lot of things I wasn't sure, about the whole saber building, but the resistors are still something I'm not quite sure.

The green LED is 2.2v 25mAh and the red one 2v 20mAh. If I understood correctly, the user decides what he wants. So let's say I want to green one at arround 13mAh and the red one a little bit brighter, about 15mAh. 82 ohm would be about it, meaning I have to get http://www.thecustomsabershop.com/82...istor-P23.aspx good so far?
If the resistor is correct, do I need two? or just one? I did not understand how the wiring for the accent LEDs resistors work, with the resistor footprint pads. Are they in serie or in parrallel? I'd like some info on how the accent LEDs are wired. Thank you.

For the rest, if I understand correctly, the main LED doesn't need a resistor, only the FoC LED? I recall the white LED is 3.1v and can be driven up to 1A. The resistor would be something like 4.3 ohm. Good so far?
Would I be better with a 4.7ohm 5w http://www.thecustomsabershop.com/47...stor-P492.aspx or a 3.9 ohm 5w http://www.thecustomsabershop.com/39...istor-P17.aspx ?

Now for the switches, they are wired to the 3.3v pad, right? They are both already 3.3v and 20mAh. If the max mAh from the pad is 18, do I still need a resistor?

I think this covers pretty much my questions. I want to be sure to buy the right stuff and to be sure I understand.

Thanks a lot

**Kyaryo Ysoyav** · 01-30-2013, 01:55 PM

Looks like for the accent LED's you will need one resistor for each if you want them at different brightness levels. You will have one positive from each LED to the PC as shown by the red lines in pg 12 of the PC manual. They share a common ground line.

You're correct on the FOC LED needing a resistor.

For your AV switches, do you want them to light up as soon as the saber gets power, or only when it is turned on? You'll likely need resistors either way, but it changes how you wire them.

**Darth Saevius** · 01-30-2013, 07:31 PM

Well, what I meant is that since I'd be using the same resistor (82ohm) for both accent LEDs one would be brighter than the other one and it's okay for me. But would I need two or just the same one?
And for the wiring, what I was asking, is that the positive goes on the accent pad and the negative on the ground pad, the resistor goes on the resistor footprint pads. How does that work? I have the diagram in front of me and it says "external resistors". I'm just not sure what it means.

For the switches, I don't care when they light up, I guess I'd prefer once the saber is on, but how do I determine what I need? It's the same voltage.

Thanks for the reply. But I still don't know if I understood correctly and if my resistor choices are okay

**Forgetful Jedi Knight** · 01-30-2013, 08:16 PM

You would have to put a resistor on each accent LED, usually the positive wire side.

The resistor pads are for those who can use tiny SMB resistors, instead of a traditional resistor. Otherwise you would just bridge those two pads together (as shown in the manual) and use a conventional resistor.

**Darth Saevius** · 01-30-2013, 08:38 PM

Okay thanks, it wasn't clear for me. I thought we had to use the pads and not just solder the resistor to the positive wire.

**Forgetful Jedi Knight** · 01-30-2013, 08:47 PM

It's an either / or thing. If you have the skills, you can use the pads. If you don't, just bridge the pads and do it the "old fashioned" way.

**Darth Saevius** · 01-30-2013, 08:51 PM

Most of the times I have no problems understanding English, but some terms are still unclear for me. I'm not sure what it means to bridge and what's to do. Is it to link two pads together? And why?