Hi everyone, I want to understand how to decide what type of regulator I need to use in a circuit. I believe it will take much time to learn it totally but as a first step I am going to ask the differences between two regulator circuits. A circuit and the 5V regulator it uses can be seen below: Another circuit uses a different regulator circuit: The question is that, cannot the first circuit use the regulator circuit in the second circuit (the one with no capacitor)? If not, why? As both of them supply a 5V output I cannot see the difference. Could you explain me why the capacitors are used?