Reply to "Surgery on Plastic Lenses for Observation Car Tail Lights"

gunrunnerjohnOGR Forum Member SUPPORTING MEMBERDIGITAL SUBSCRIBER

It's actually pretty easy to calculate resistor values in your head for common 20ma LED's. You also don't have to be exact, just err on the side of more resistance and not less.

For each volt you need to drop from the power to the rated voltage of the LED, use 50 ohms.

For example, you are using a 12VDC power source and want to light a white LED. You need to drop 9 volts as the white LED has a 3V operating voltage. 9 times 50 is 450, so a 470 ohm resistor is a very common value and is a perfect choice.

5/20/2210:34 AM

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