Zlim

ok, so i bought some leds (3v 20mA) and i want to wire 4 of them in series on the 12v molex. as i understand it if i do so i dont have to use an resistor.

how do i know wich one of the pins that is the +/-?

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xie67

The LONG LEAD is the ANODE and the SHORT LEAD is the CATHODE.

cheers

edit : ANODE = +ve and CATHODE = -ve

tdunks

You connet the +12v line to the first positive then that to the negative so its 12v + - + - + - + - gnd the +12v is the yellow wire on 4 pin molex and ground is black.
here is a pic:

If you want more then 4 you can do parallel series as shown here:

Zlim

isnt the red one 12v and the yellow 5v?

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tdunks

You have that backwards. it is yellow-black-black-red(12v-gnd-gnd-5v). My guide for LED wiring is in my sig.

Zlim

WOOT?
according 2 casemodgod this is hov u wire them in series...

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tdunks

You dont ned a resistor if you use 4 LEDs though. but yea that is right minus the resistor and plus 2 LEDs

xie67

You need to limit the current through the LED to about 15mA eventhough it is rated at 20mA.

They illuminate fine on 15mA.

As they are 3v ( forward voltage or working voltage) to run 1 only in a 12v circuit at 15ma you would require a 600 Ohm resistor to do 3 in series you would need a 200 Ohm resistor.

To do 4 in series will require no resistor.

Hope that helps you out.

cheers

Zlim

thx rep 4 u

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Anzen

A resistent isn't always necessary.

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-Anzen