wiring an LED and switch?

[pcgamer4life]

I've got a couple questions, most of which have probably been answered before, but I searched and couldn't find anything of use.


1.How would I go about wiring an LED to a toggle switch for my car?
2.How would I go about wiring up multiple LEDs to a toggle switch for my car?

I've got a some 3 "pronged" switches: Ground, positive, and Acc(essory?).

Would I need to wire the 12v battery source to the resistor, then that to the + of my LED, then that to the Acc, then the negative battery source to the negative on the switch and negative on the LED?

I'm at a loss here, please help.

[SolidxSnake]

It goes like this:

+12v source-->resistor-->switch-->LEDs' + leg-->LED-->LED's - leg-->COM

[4GHZ_or_bust]

To find the size of the resistor, use this simple formula:
vsource - vLED / iLED

vsource would be your car's 12v. vLED is the rated voltage of LED> A typical red and green is 2v and blue and white is 3v. Other LED may require more or less and if you use multiple LEDs, they should have each its own resistor as not all LED are perfect and single resistor for multiple LED may lead to minor problem.

iLED is the rated current for LED. Typically 20ma (convert to amp or 0.02) for red and green and more for others.

Assume you are using a single red LED< your formula would be 12-2/0.02 = 500 ohms. It is the bare minimum and generally higher value for safety (about 10% higher) so 550 ohms is what you need. Since 500 ohms is not a common value, the nearest common value is 510 or you can put 2x 1K in paralel to get exactly 500 ohm.

LED are also polarity specific. Usually the short lead of the LED is cathode for negative connection and longer is anode for positive connection. Resistor is not polarity specific and can be used in either position.