CONFIDENT NOOB HAS MINOR FoC PEX ??

[JEDI ERIN]

Hello forum, I have been reading threads now for months and have successfully built 2 stunt sabers. one using a 1000ma buckpuck w/blue rebel, the other has a constant current driver w/ blue rebel. the both were a success becuase of all of your insightfull posts. I feel I'm ready to take on sound and have puchased my first PC 2.0. I have read the manual (twice) and have only one question that I could not find an answer to on the forums. I am going to be using a tri-rebel Blue-Blue-White, bridging the blues and having the white for the FoC. My question is, what resistor to use on the pex? I understand nothing about the formulas to figure this out. I am purely not an electrical person, I just love STAR WARS and saber building has always been my goal, even w/out the electrical knowledge I have done very well thanks to Tim and all of you on the forums. I apppreciate any help I can get in this crazy, fun, obsession in saber building. :p

[Silver Serpent]

http://led.linear1.org/1led.wiz is your friend for calculating resistors.

Source voltage will be whatever your battery pack is rated at. Probably 7.4v if you're using a 2x li-ion pack.

Rebel whites should be 3.1v@1000ma.

[JEDI ERIN]

Yes, I am using 7.4v li-ion. I'll check out the page for the calculation and if my electronic impaired self cannot figure it out I'll be back,ready for a tongue lashing of course. Thanks Silver Serpent for the info.

[JEDI ERIN]

I'm Back, O.K. the wizard on the page gave me 4.7 watt 4.7 ohm, there are no resistors on the tcss store page resembling these numbers, and dont get me started on the radio shack short supply of resistors. so what should I use?

[Silver Serpent]

Wattage is a minimum. You can always use a higher wattage resistor without affecting brightness. Don't go overboard, since higher wattage resistors take up more room in your hilt.

There are two different 4.7 ohm resistors in the shop that will work. http://www.thecustomsabershop.com/47ohm-5w-resistor-P492.aspx and http://www.thecustomsabershop.com/47ohm-10w-resistor-P19.aspx I'd choose the 5 watt version.

[JEDI ERIN]

O.K. good to know. I just saw the 5watt 4.7 ohm. After ordering I think I'm ready to begin my build. Thanks to you and all involved in this awesome community.

[patolcott]

what does the wattage affect then?

[Jay-gon Jinn]

Excess voltage mostly, but it also affects current to an extent, since the two are relative to one another.

[Silver Serpent]

Wattage rating determines how much power can be dissipated by the resistor before it lets the magic smoke out.

[JEDI ERIN]

Happy Holidays, I just recieved a box from TCSS and WOW goodies. The 4.7 ohm 5watt resistor is huge, like 4x the size of the PEX. Is that right? I've seen photos of a PEX with the resistor soldered "on" it. This thing could hold a few PEX's on it. I just don't want to start my build until I have everything worked out, better safe than fried.

[Forgetful Jedi Knight]

5W resistors are "large" in comparison to some smaller resistors. Some of us have been known the refer to them as "Big Honking Resistors (TM)". The PEX with resistors you have seen probably had smaller resistors on them because they were powering 2 dice where as I am guessing you are only powering one (I haven't read through this whole thread), hence why you need a "Big Honking Resistor". ;)

[Kevin Starwaster]

Happy Holidays, I just recieved a box from TCSS and WOW goodies. The 4.7 ohm 5watt resistor is huge, like 4x the size of the PEX. Is that right? I've seen photos of a PEX with the resistor soldered "on" it. This thing could hold a few PEX's on it. I just don't want to start my build until I have everything worked out, better safe than fried.

Yeah, as stated above, the thing is huge. You could just bend the wire coming off of it, so that it bends around the corner of the resistor (gently, though it is sturdy enough to do this with). Then about 1-2 millimeters down bend it back so that it protrudes away from the resistor. Do that with the other wire with the goal being to space them just far enough apart so that they will fit into the resistor holes on the PEX. Cut off the excess and you'll have a nice compact PEX/resistor package. Solder it in place.

You could also wire a single 'male' JST to the resistor holes. That would let you easily insert and remove the resistor if you anticipate changing it at some point in the future. Like if you were going to change LEDs and needed a different resistor on there.

[JEDI ERIN]

Thanks guys, just wanted to be sure on everything before I get started. This is my first build with sound and am having a hard time not rushing into. Patience, I believe is what I need to get it right the first time with no blow outs. Will post pics as I get along.