Wiring LED on 12V

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Thread Starter


Joined May 15, 2007
I am trying to make an alternating, blinking 3rd brake light for my truck. I saw one at a show awhile back so I know its possible. The guy that made his own, didnt know much about how he did it. He just said he played with it till it worked.

I want "S T" on one side and "O P" on the other. I have a LED controller off Ebay that will control the alternating and blinking of the sides. What I need to know is what size resistor, if any to use. Do I wire the LEDs in parallel or series? The LEDs are 2V, 20mA.
There are 18 LEDs in the "S T" and 22 in the other side.
This is the LED controller.
These are the LEDs.
I used these parts because this is what the guy at the show used. I just need to know about the resistors. Thank you all.


Joined Apr 19, 2007
Hi... You need to check the spec's on the LED's.Normaly they will run quite happy at 20mA. So if the they have a forward voltage of 2 volts, you can put 5 of them in series (10 volts) and then a resistor in series with them to give the correct current through them (20mA) 100 ohms.This will give you set's of 5.Then just put the set's of 5 in parallel as you need them..............Good luck.......Daniel.
Just thought !!!... I asume that the truck supply is 12 volts...If it is 24 volts you can put 11 in series and the 100 ohm resistor...... Dan.
......OH WHAT.. of course it's 12 volt, it says so in the question.... much too early in the morning for me....... Dan.
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