As you can see, this circuit is a little more complex than the half-wave. This circuit requires the use of a centre tapped transformer. You may also notice that this circuit contains two diodes! There is a simple reason for this, efficiency! Now, how is an extra diode going to make a rectifier more efficient? I'll tell you how!  But once again you must imaging that we could stop time every 180 degrees. You must note that the bottom of the transformer's secondary is 180 degrees out of phase with the top. Which means, as the top of the secondary is in the positive alternation, the bottom half is at the negative alternation. So, how does it work? Well, when the top of the secondary produces the positive alternation, the anode becomes more positive than the cathode. You got it! It forward biased the diode! You can see this in the image as the first alternation. Now, at the same time the bottom half of the secondary is in the negative alternation, making D2 reverse biased, allowing no current. So how does that second positive alternation get there? Well, now for the next alternation. The top of the secondary goes into it's negative alternation, causing the anode to be more negative than the cathode, causing the diode to become reverse biased. At the same time, the bottom half of the secondary goes through it's positive alternation. Just like above, it causes D2's anode to be more positive than it's cathode, forward biasing it, causing the second positive output alternation! Thus recovering all 360 degrees of the cycle!! Now it's time to get fancy with them!