35mA led with 25mA pic output?

[xnihilo]

There are LEDs and then there are LEDs. They can vary widely in their brightness output. For example, these are 2 green LEDs in a 5mm, T-1 3/4, thru hole package. Both are rated at a test current of 20mA.

http://search.digikey.com/scripts/Dk...me=511-1191-ND
This one has a rated output of 100mcd. This is typical of commonly available LEDs, 50 -300mcd.

http://search.digikey.com/scripts/Dk...FPG1-15Q-A3-ND
And this one has a rated output of 34,000mcd.

The output of the 2nd. one is 340 times that of the 1st. And it is not even a matter of price - both of them are about the same. So if the LED is bright enough for you at 20-25mA, just go for it. If not, get a brighter one. No need to mess with paralleling outputs, using BJT's or MOSFETS etc.

34000mcd... awesome! I didn't even think such exist
What if I put one on my car ...

[skimask]

34000mcd... awesome! I didn't even think such exist
What if I put one on my car ...

34000mcd (http://en.wikipedia.org/wiki/Candela) sounds really bright and really impressive, and they are fairly bright when viewed straight on...but it's not all that.
These are what I used in my toobz...
http://www.philipslumileds.com/pdfs/DS05.pdf
70mA drive current with a 1/2 power viewing angle of 90 degrees.
They aren't the Luxeon super bright, multi-watt, power LEDs, but they do well.