You all missing the point of what this thread was for.
cowana....i think you are mistaking an op-amp for a voltage regulator? an op amp takes a voltage, and multiplies it, based on the resistors selected that are connected to it. For instance, a 1k and 9k resistor, i think, puts a 24volt on the op amps output from a 5v supply to the output.
Now a voltage regulator, yes, some, even most from my understanding, does have a voltage drop across them of around 1.25 volts, some even higher, and they can't output any higher than than the supplie voltage to it.
rstofer. That's all great and all, IF i had more than 5volts to drive 2 or more LED's in series. I don't, I only have 5v to work with.
dacman.....Why? That's just added components, and I still have the problem with only having 5v to drive multiple LED's in series (which can't happen, maybe RED color I can drive two, but that's it).
I did a search the other day, someone was using a op amp with 5 volt input and controlling 4 white led's that were motion sensors, they turned on and off as he waived his hand. His schematic showed the 4 white led's connected directly to the output of the op amp. But, I can't seem to find the video now or the schematic.
Guess I'll try and see if I have one and see if it works or not.