For the Center-Tapped Secondary Full Wave Rectifier, the PIV is double the Vout. OK, but I can't see why? Not much luck on Google. Lots of info on what full-wave rectifiers are but not why PIV is double. On Stack Exchange, I found opposing answers that basically said it only needs to be double when there is a capacitor on the output. I can understand that but not when there is simply a resistive load? The negative peaks are 180° apart so why would they be additive? Or... Are the peaks additive due to the secondary ground tap?