Do RGB LEDs have very different brightness levels?
I'm running an RGB LED (common cathode) via some TIP120 transistors, controlled from a raspberry Pi.
There is a 5v feed from the rPi.
Initially I had ~2k resistors in series with the output pins and the base of the trans. but they were failing to trigger so I've removed them.
I also then had what I thought were the correct resistor values in series with the LED (82R and 150R for red and blue / green respectively) but they were so dim as to be useless.
So those have gone as well.
So against everything I know to be "right" I've got no resistors on the LED or the output pins. The red is nice and bright but green and blue are still both pretty dim. I'm controlling with software PWM from the pi and have had to limit the red channel to 25% of the green and blue just to level things out a bit.
Any idea what's going on?