Thank you! If I will use a 12v supply should I modify something?
I'd use NPN connection on cathode side for all arrays, same as the top left 1/3 of the schematic.Then a high from Arduino to turn on each transistor individually.
12V is only enough for two LEDs in each column.
76, one transistor, no problem.
Thank you! How can I compute the max string of LEDs er transistor?
Hooray for CrossRoads and fungus! Thank you!