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LED wiring question with diagrams
Timoe:
Anybody know the wattage on these resistors? are they 1/4 watt?
(I know that I need 100ohm) And I would gladly buy them from GGG with the resistors included but I need non standard colors.
BobA:
1/4 or 1/8 W will work fine in that configuration based on 100 ohm resistors.
Just to be safe what color are your LEDs and what ma do they run at?
RandyT:
A couple of comments:
First, the resistor can be on either side of the LED. It's a circuit, so placing it in series anywhere in the circuit will have the same effect. The resistor limits the flow of current, just as a valve limits the flow of water in a hose. If you had a flow meter in the center of the hose, placing the valve on either side of the meter would result in the same amount of flow through the meter.
And the other is...technically, you should be able to drive multiple identical LED's through one resistor, as long as it's large enough to handle the combined wattage of all the LED's in the circuit. EE types frown on this approach because of the manufacturing variances in the LED's, which makes it difficult to know just the right value to use when multiples are considered. It also has the effect of cooking every LED in the circuit if one of them should happen to blow (the current the blown one used would then no longer be consumed, so it would be distributed to the other LEDs, creating an over current situation.) But if you don't mind taking that chance, and you don't run them at the bleeding edge of tolerance, then you can simplify things a bit by ganging them.
However, for a single, standard 20ma superbright, !/8 watt will be plenty. 1/4 watts are more common, so they are often easier to find. You can always go bigger without a problem, just not smaller.
RandyT
Timoe:
Thanks Randy. I wish I could just order through you when we order all our other stuff. You sure you cant get some violet or pink button plaster leds?
bfauska:
I am totally uncertain about this but it seems to me that you could wire two serial pairs of LEDs in parallel, assuming that the LEDs were rated for >2.5v each.
Is that not correct, I could swear I have looked around and seen equations that make this sound correct? Randy? I would totally trust your opinion on the matter if you happen to check this thread again.
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