A question regarding power supply efficiency: The theoretical maximum efficiency of a full-wave rectifier circuit with a resistive load and no smoothing is around 82%. In the calculations to derive that the resistance of the source or the rectifiers does not enter into the equation, so the first question would be: If the loss does not take place in the resistance of the source or in the resistance of the rectifiers where does it take place? I had also assumed that a similar theoretical limit applied to a capacitor input filter, but have been informed that this is not the case and the efficiency can go to 100% with a rectifier and source with no resistance. Why is this the case? Thanks for any insight.