This question is about designing a split power supply from a transformer and a rectifier. I'm trying to understand why a full-wave bridge rectifier with a center-tapped transformer is not affected from loading comparing to a not center-tapped one.
In below schematics both configurations are simulated in LTspice. The only difference is the one on the left side uses the transformer as center-tapped and the one on the right uses the transformer the transformer as usual.
X and Y represents the terminals of the split supplies. Both supplies gives the same output at X and Y terminals without any loads. They both output around +8V and -8V when no loads attached. But as seen in the schematics, when I load both supply terminals with two different loads 1k and 100 ohm, the output voltages at the X Y terminals becomes as:
It seems like one should use a center-tapped transformer to create a split power supply otherwise the loading corrupts the output for non-symmetric loads.
My question is: I can verify this by LTspice but I do not understand the reason behind. How can we explain this difference logically?