I am terrible at math, so I just can not calculate the resistor I need. I will be using the PC 2.0, FoC, Tri-Rebel Star BBW, and 7.4v Li-ion 800mAh 14500 Battery Pack. What is the proper resistor in the store that I should get?
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I am terrible at math, so I just can not calculate the resistor I need. I will be using the PC 2.0, FoC, Tri-Rebel Star BBW, and 7.4v Li-ion 800mAh 14500 Battery Pack. What is the proper resistor in the store that I should get?
Let's get to a relevant piece of information you didn't include above... what color will the FoC be?Quote:
Originally Posted by Renaissance Jedi
Also as a FYI, while technically FoC will work with the battery pack you mentioned, you will not have a very long run time at all. ;)
There are also resistor calculators available on the net. I use the one I found over at CandlepowerForums. It should be noted that these programs are usually developed by hobbyists, and should not be relied upon as the only source of information. Programs can have unknown flaws or bugs.
Aside from that, you might also check the forums for similar setups. The search function can narrow down your work considerably. I would look at FenderBender and other pro smiths. Sometimes you will find a complete build log that is relevant to the setup you want.
He won't be able to use the calculators if he doesn't have all the relevant info ;). The math is easy if you have the facts.Quote:
Originally Posted by BlessedWrath
Okay, so I'm using the Tri-rebel star BBW. White is the FoC color. You say that I should use a different batter pack? Which one should I use? I should mention that I am going to have very little room in my hilt as I am using on of the blank blade holders which significantly reduces the amount of space available for electronics if I'm going to keep my hilt under 1 foot, so a larger battery pack is not possible.
Oh, and technically couldn't I just use this: 20mA DynaOhm™ Variable Resistor?
Sorry for sounding like such an amateur. I really have been on the saber scene for a while, I've just never used FoC before.
Also, for reference, here is the internal view of the hilt.
Attachment 8690
Sure, if you only want 20mA going to your FoC LED :pQuote:
Originally Posted by Renaissance Jedi
The DynaOhm in the store is the same as the current regulator on Petit Crouton, it varies voltage to give the specified current to the LED it is attached to. On Petit Crouton this is whatever you set in the configuration file, but for the Dynaohm it is set to 20mA, purposed for driving small accent LEDs.
As for calculating your resistor, it's simple ohm's law (for which there is already a very extensive guide on this forum).
R=V/I
In other words, your resistance (in ohms) is equal to your desired voltage drop divided by your desired current (in amperes).
The white luxeon rebel has a Vf of 3.1V and can be run at 1A. This gives us the equation:
R=(7.4-3.1)/1
Hence:
R=4.3Ω
Now we need to calculate power so we don't burn out the resistor. We use the formula P=IV. Power (in watts) is equal to current (in amperes) multiplied by voltage.
P=(7.4-3.1)*1
P=4.3W
Therefore you need a 4.3Ω resistor with a power rating greater than or equal to 4.3W.
Quote:
Originally Posted by Renaissance Jedi
Well... I won't really comment on the design, and if you don't have a lot of room, it is what it is.
For the original question, like Skott said, you will need the 4.7 Ohm,5W resistor that is sold in the store. I would recommend the 14650 pack IF you had the room.
Thank you to everyone who helped me out with my issue.