led load resistors

[bigtallsam]

hi all

does anyone know what value/type of resistors i should use on an led tail light bulb?

i know they're a bit ricer but i quite like the look of them on the car but would like to stop the obc bonging at me

regards

sam

[pingu]

You can work out what resistor value you'll need using V=IR and P=(I^2)R.

I presume you'll need a resistor for each bulb.

Sizing the resistor to make the new setup (i.e. the current drawn by the resistor together with the LEDs) use the same current as the old setup should fool the OBC, though you can probably get away with a higher value resistor and still fool the OBC.

Bear in mind that the resistor(s) will probably dissipate several watts (just like the old bulbs) and so might get hot. When you choose your resistors, you'l need to get one(s) with the correct power handling ability as well as the corrrect resistance.

[Qube]

Here you go: http://autolumination.com/equalizers.htm

[bigtallsam]

DOH!

AND DOH! AGAIN

i can't belive i forgot it was a simple as a basic physics equation!!!!:D

thanks for the reminder

s

[bigtallsam]

here's a handy little online thing to find 'R'

http://www.the12volt.com/ohm/page2.asp#top

if my calcs are correct a normal 12v/21w tail bulb uses about 6.857 ohms

so.... will a 21w 2.857ohm load res do ok or do i really need to take into account the led specs??


s