QUOTE(autogeek @ Aug 14 2007, 05:22 AM)

can anyone help me figure out a way to hook 3 bright LEDS in my car with the 12v output of the cigarette lighter?
can anyone help me with a simple diagram of how to do it?
OK, you need to use OHMS law. Voltage/Current = resistance...
So the led will need around 10ma of current and have a voltage drop of 0.7V. You will need to check the current the led requires, the bright white ones may need more....
SO... the maths is:
12-0.7 = 11.3V
10ma of current
11.3/0.01 = 1130 ohm
so I suspect round that down to a 1K resistor. Depending on the brightness of the LED, I've seen them driven from 680 ohm to 1K.
To wire it up, one side of the resistor goes to the +12V terminal. The other side of the resistor goes to the LONG leg of the LED.. the short leg of the LED goes to the ground terminal ie: chasis etc....
If you want 3, replicate this 3 times....
Cheers..Pete