I've recently started playing around with Arduino. I've got quite much experience with programming, but I'm a beginner regarding electronics.
I recently stumbled across this schematic: Arduino simple signal generator and I just don't understand why this works. I think I understand what happens when only one output is high at the same time (how the voltage is divided between the resistors and why the voltage at out is like it is). But I can't explain what's going on with two or more outputs high. Please give me some advice what's happening in this case.
