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Automotive LEDs...
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whammoed:
led's need  a resistor when they are rated for a voltage lower than that wich you are supplying.
Bottome Line.
a 12 volt bulb rated at 0.5 amps will draw 0.5 amps from a 12 volt supply regardless of the power supply rating.
Sinner:

--- Quote from: whammoed on February 06, 2006, 03:23:57 pm ---led's need  a resistor when they are rated for a voltage lower than that wich you are supplying.
Bottome Line.
a 12 volt bulb rated at 0.5 amps will draw 0.5 amps from a 12 volt supply regardless of the power supply rating.

--- End quote ---
I understand what you're saying, but I don't necessarily agree...resistors would limit the current, not the voltage...

whammoed:
Never said it limited the voltage.
Did you even look at ohms law?  It is pretty widely accepted.  ::)
Sinner:

--- Quote from: whammoed on February 06, 2006, 06:35:49 pm ---led's need  a resistor when they are rated for a voltage lower than that wich you are supplying.

--- End quote ---
I guess I read this as you were saying you needed a resistor to change the voltage...

As far as Ohm's law goes, wouldn't I need to know the amperage rating of the LED to figure out the resistance needed?
whammoed:
to figure out the resistor you need (if you need one) you need to know the amps and volts for the led and the volts you will be supplying.
this site will do the calculation for you:
http://ourworld.compuserve.com/homepages/Bill_Bowden/led.htm
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