Re: Basic question

saketram wrote:

A simple question, just to know about theory.

Suppose I have 12v DC @ 1A, 1.5 LED.
How much power resistor do I need to use to glow the Diode?

Should I use 12 ohms as,
R = V/I = 12/1 = 12 ohms

or should I use 10.5 ohms as,
R = V/I = (12 - 1.5)/1 = 10.5 ohms
(as 1.5 LED will consume 1.5v).


Thank you.

Saketram

you need to know the I (current) of the LED ?
lets assume for now, it's 20ma at 1.5 volt
across the diode.

R = (12-1.5)/I = (12-1.5)/ 0.020 = 525 ohms

like i said, you need to know the (I) of the LED..
its also best to operate the LED at a little less than
spec. so a 680 Ohm would do just fine, which is a more
common value.
that's the closes i can come up with for you.



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