I'm relatively new to electronics (stuck with software development for years, and starting to migrate over), and one of my first useful projects is going to be a LED backlit sign. The sign will have at least 3 banks of LEDs (haven't decided yet entirely, because there was a trick I was thinking about that would use split the one section into a few more banks). I was thinking about using a 08M, or more likely a 14m (because it has more outputs, and thus would allow me to do the aforementioned trick), with the outputs to a darlington driver (most likely an 8 channel ULN2803) so I could effectively drive the various banks without taxing the picaxe too much. The issue I'm coming up with is that the LEDs I was able to get of each color (Red, white and blue), are all different brightnesses. The red is 4000mcd, the blue is 5000mcd, and the white is 13000mcd. The white and blues are both 3.2 forward volts, with 20 mA. The red ones are 2volts and 18mA. Each color will be in its own bank. What I want to do, is have the picaxe control the brightnesses, so that I could have the various LEDs appear to be approximately the same brightness (more important on the red and blue, but I do want to tone the whites down). I could do that with various components in a permanent fashion, but was wanting to be able to fade the LEDs.
What would your recommendations be?
What would your recommendations be?