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Eltronics help needed

  Clio 1.4 16v
To put lower voltage LED's into the 12 volt power of me car, what resistor will I need, thanks


ClioSport Club Member
  A blue one.
Here's the famous pyramid....


V = IR
I = V/R
R = V/I

You need to use the bottom equation. Your LED will have a current rating, most are around 20ma, but will depend on brightness & colour.

R = 12/0.02 = 600 Ohms

And the other thing to make note of:

P = VI (Power in watts)

P = 12*0.02 = 0.24W

So you need your resistor to be at least 1/4 of a watt rated.

Just replace 0.02 (20ma) with the rating of your led in the above equations and you should be good to go.


ClioSport Club Member
  A blue one.
OK, probably a silly question, but can I find the current rating with a multimeter?

No. It'll have been specified either in the catalogue or on the packaging (if you bought from tandy or such like).
  Polo + Micra
i've used this before to find out what resistors to use

yeah it's all about current when it comes to led's
  Clio 1.4 16v
too complicated, lol

I like the simplicity of the other one, just gotta hope its right and all my LED's don't blow :)