I'm going to make 12V DC power source for my project, using a transformer (230V AC to 15V AC) and full wave bridge rectifier, followed by LM7812.
The load will be 200mA DC.
That is all perfectly OK, I understand it pretty well.
But there is one thing that is not clear to me. Do I have to select transformer that is capable of providing 200mA or 450mA?
Transformers specifications usually say:
Power rating: 3VA
Secondary voltage: 15V
Secondary current: 200mA
example: TR Z03.00/15
I know that I should not pick transformer on the edge of current rating and have some margin. But my question is whether to use RMS value (200mA) or peaks value (450mA) for the selection.