modified 9 years ago

parallel on fire

00:54:52

do not touch

published 9 years ago

Robert_Kidd

9 years ago

Make resistors 1900 Ohms to give correct current of 20mA.

Hamzah8

9 years ago

Robert, I think Mrcool was trying to tell a joke on this comedy circuit.

Robert_Kidd

9 years ago

Yes, I agree but some may learn from it :-)

HannibalBarkas

9 years ago

How you get the 1900? V=RI ?

Hamzah8

9 years ago

Agreed, Robert. :) Han, Robert was trying to tell us to change the value on each resistors, so we can adjust them from 100 to 1.9k (1900) and it's not that formula. You can tell by look at circuit after change resistors' value

HannibalBarkas

9 years ago

I've turn it to 1900, but how can I calculate it.. Is it possible?

Robert_Kidd

9 years ago

The supply is 40V. We want 2V across the LED, leaving 38V to drop across the resistor. We want LED current of 20mA (=0.02A). Rearranging V=IR, R=V/I, so R=38/0.02=1900 Ohms. Hope this helps.

HannibalBarkas

9 years ago

Thanks, yes! Now it make sense! :)

Robert_Kidd

9 years ago

You are welcome :-)

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