if you look the the "connects to cathode layer cable" section i can understand they are using a 2n2222 transistor to sink the current which is coming from the cable to the ground but if you look at the bottom the "cathode layer cable" is connected to 5v why?
Those resistors are there to pull up the collectors to 5volt, when the bases are not driven.
Using pin 0 and 1 of an Uno is a bad idea.
Leo..
I guess those are pull up resistors. Maybe to prevent some residual light from leakage currents of the transistors. I don't think they are needed but it should cause no harm.
if you look at the bottom the "cathode layer cable" is connected to 5v
It's not connected to 5V. It's connected to resistors that are connected to 5V. These are very different things. To be connected to 5V the resistors would be replaced by wires.
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