LED Resistors and Ohm's Law

[Arkhan]

you would have to come up with a compatible array of LEDs. If you wire them all in series, you can't deal with the forward voltage requirement.

If you wire them all in parallel, you end up putting a resistor on each of them, or a very large resistor in front of them.

If you create an array, mixing parallel and series, you can keep the forward voltage reqs down into manageable range, while reducing the # and wattage of resistors necessary to protect them from over current.

If you google for LED parallel/series calculator, there is one I have used that will take the info about your LEDs, your power source, how many of them you have and create a workable array for you.

[morpheus1977]

so if I want to wire up let say six of these
http://www.radioshack.com/product/in...ductId=3097460
using 3 AA
this is how I would want to wire it up?

Then I would just place a mom switch on the battery neg wire.
after looking at the radio shack website it looks like they dont have exactly what the calculator recomended.
It suggested.
1/4 w
56 ohm

the closest I could find was
1/2 w 47 ohm. so it looks like they will be overdriven. a little.

[RevengeoftheSeth]

Doesn't Makoto just wire his all in series? The voltage stays the same, but the mA stacks per LED.

For instance, you have 10x 3V 20mA LEDs which requires 3V 200mA to power them sufficiently.

[Rhyen Skytracker]

In series the voltage will split and the current stay the same, it is parallel where the current will split and the voltage stay the same.

Morph,
You can use down to a 25 ohm resistor. Those LEDs have a max recommended voltage of 4 V so:

(4.5V source - 4 V forward) / .02A = 25 ohm resistor.

[morpheus1977]

Thanks Rhyen
the lowest I could find is 33 so I will use that. I want these nice and bright. I will be using diffusers with them.

But this is going to be ugly wired up.(yea it will be in the lancer but still ugly)

quick question instead of having to buy a three AA battery pack. I still have the battery sled from my MR Vader saber can I use that?

[Rhyen Skytracker]

Yes, you can use it if it will fit.

[morpheus1977]

ok got it can somebody tell me which is pos and which is neg?

*edit* never mind figured it out LOL