Hi all,
I have an USB connector powered by 5V source. To indicate readiness I added a LED (3.2V, 0.02A). Using Ohm's law I calculated a resistor of 90Ω. LED was too bright so I used 160Ω... too bright - 220... 1k... 33k... 100k - and hardly reached acceptably low brightness. In my understanding, there should be 0.000018 Amps so why does the LED so happily shine? Why would anyone calculate resistance when even 1000 times higher resistor makes no difference? What am I missing here?
Thanks for your advise.
j.
I have an USB connector powered by 5V source. To indicate readiness I added a LED (3.2V, 0.02A). Using Ohm's law I calculated a resistor of 90Ω. LED was too bright so I used 160Ω... too bright - 220... 1k... 33k... 100k - and hardly reached acceptably low brightness. In my understanding, there should be 0.000018 Amps so why does the LED so happily shine? Why would anyone calculate resistance when even 1000 times higher resistor makes no difference? What am I missing here?
Thanks for your advise.
j.