AC to DC power supplies

The basic info is good. There is a problem with the right transformer, as drawn one half of the secondary windings are shown short circuited. The txfmr appears to be a center tapped type of device, not a bifilar type that is required for a 2 diode fullwave rectifier circuit. This is the reason for the strange output voltages. http://everycircuit.com/circuit/4682639917973504

Center tapped transformers requires double meters of wire windings than normal trasformer (you can see this removing your shortcircuit as Billy said). For this reason they are usually bigger and more expensive than the normal one, having the same power and the output voltage characteristics for each side of windings. Their advantage is that they needs only two diodes, instead four. This was convenient only when tubes were the only rectifiers available, because other two tubes were much expensive than double copper wire meters. At our days is more convenient add two diodes instead, using a bridge and normal transformer. To compare rightly the your three solutions, please double the voltage of the right example.

http://everycircuit.com/circuit/5321124152606720

BillyT, I see what's making my right transformer acting weird, besides the short circuit. I played a little bit around with your circuit and saw what makes your "center tapped" transformer work better than mine. Thanks for sharing!

giomix, I fixed the secondary windings. It makes sense that a center tapped transformer needs double the amount of windings on the secondary side. Thank you for sharing