I am attempting to build a gel transilluminator using RGB LEDs instead of UV fluorescent bulbs. Blue/Green LEDs can excite many fluorescent dyes similarly to UV without the harmful effects of UV. I would also like to make white light an option so we can image non-fluorescent gels. While I'm at it, I can include a blue only option because blue light illumination is also common.
Anyway, I thought the simplest way to do that would be a large common anode RGB LED array. Rather than trying to control each LED separately, I will wire them all up in parallel, with three switches to turn on each color all at once, so I can choose blue/green, blue, or white by turning on different combinations of switches.
I have a 12 V 5 A DC power supply. I know I need a resistor on each color channel, but is one resistor on each channel enough for what I want to do? Or will I need 3 resistors per LED? I also need to run the LEDs at a high current so that they are very bright, so "recommended" resistance levels might be too high, I'm not sure yet. I am okay with reducing the lifetime of the LEDs a little because transilluminators are only turned on for a few seconds to minutes at a time. I am very new to circuit building so I'm sure there is something I'm missing.