I have built a really simple 120VAC to 12VDC 2A power supply. Here is the schematic and the PCB.
As you can see, the power supply does strange things. The frequency of that bump is about 5 ms and it has a width of about 0.2 ms. I think it is generating inconsistency in my op-amp readings because it gets extremely noisy.
Anyone could help me improve that design with some explanations?