This is an old style bridge rectifier i found in a reel to reel tape recorder
This is the layout for the bridge
Below are 2 types of xingle phase rectifiers, most commonly used in power supplies
Mainly in industry you are likely to find 3 phase rectifiers like this
And in rare industrial systems you may even find a 6 phase rectifier
Just to note, a rectifier does NOT change AC to DC, a half wave rectifier only allows positive half vycles to go through on the positive cycle only, a bridge rectifier does the same thing except on both half cycles, so you get positive going waves.
To get any sort of DC you would need to add a capacitor to 'smooth' the waveform