40ma limit ?

Other Hardware General Electronics
8

electrofunkdaddy:
Thanks Mike :slight_smile:

So the resistor is limiting what the led's are pulling less then 20ma , does mean that they are not at there optium current for optium brightness?

With 270 ohm resistors? Yes.

Trying to run LEDs at "optimimum brightness" using resistors is usually futile. You have to control the current going through the LEDs, not the voltage. Resistors will get you close ... but if the LEDs have to be matched for brightness it won't work.

The easiest way to control the current is with an LED driver chip. Something like the TLC5940 is commonly used for setups like this.