Sorry, but I'd have to disagree with that. I'm used to buying LEDs individually & soldering them into a circuit. There's loads of places that sell LEDs with wire on the end that doesn't have a resistor in it.

If the LED is rated at 3.3v and you're only supplying it from two AA cells, there's little point in a resistor.

Other than that little factet, we both appear to have the same outcome (note: it's not the 1st formula - the one you quoted - that's right, it's the 2nd)

Edit: Also, since there will be a resistor to drop from 12v to the LED input voltage, you could use both my first & last formulae to work out the parallel resistance required.

That's not an LED circuit though, it's just an LED. This is your own link I'm referring to here :)

I've been writing very badly all the way through this, I just realised... Left out bits I meant to, which probably makes it confused nonsense in places. If I add in about 20 "in a bike application" and "according to the links" it'd work, I think :roll:

Markyboy wrote

I wrote

Baph wrote

Northy wrote

Maybe I was just lucky :wink:

I'm no expert and a lot of people on here know there stuff about electric and I'll pull my head in if if got the wrong end of the stick....

would these not work a 12v resistor

I'll agree to that! Although the link I provided was merely an example application of LEDs. You only need a resistor if the supply voltage exceeds the input voltage.

DoubleD, brown blue black gold. That's a 16Ohm resistor. Depends entirely on what you wanted to use it for. :D

Dunno, they look suspiciously wee though. I think those are intended as series resistors with a stand-alone LED? Could be wrong. But I'd be really surprised if those are going to be able to deal with the job, they want to be 10W or more really I reckon. (rule of thumb, that)

http://www.ultraleds.co.uk/product_i...075c5174cced41

This'd work. Also, be ridiculously expensive ;)

Is what i have/had, until the indicators backed up that is...darn water

I have 2 of those sitting in my tool box at home doing nothing, brand new, I got them when I was going to put LED brake lights on my cage to fool the light check computer. Didn't go ahead with it though.

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