Audio, is that true I would still need to test every LED even if I know the LEDs I have are the same ones I linked a spec sheet to in a prior post? What is the variable, current? I hooked those LEDs up with 3 new energizer batteries without resistors and it worked great but after being educated that shouldn't work, and I don't want to have the possibility of blowing the LEDs every time I switch out the batteries.
Sceadwian, the issue I have with the switches is that I am using this grid (4x4) as a back light. The light would have hot spots and low spots without all the LEDs lit at the same time. Best case scenario would be being able to dim the LEDs to what is needed, and thus save battery life by only using what is needed.
Alex, I looked up a data sheet for the chip you mentioned and the cost seems reasonable. How is it hooked up and what other components are required?