Full-Bridge Rectifier.
9V 60Hz source.
Notice the voltage not being 9V at all due 2x forward voltage drop of the diodes. And so the small "flats" on the output are also due to forward voltage of the diodes.
Increase the voltage at the source and see them "disappear".
Follows Full-Bridge Rectifier: https://everycircuit.com/circuit/6073208297750528
