Topic locked, so I'll start a new one.
A resistor inserted at the center tap of a full-wave rectifier acts the same as adding two resistors of the same value, one in series with each diode, and could be modeled as extra resistance in the secondary. Of course the dissipation? is doubled (RMS current is 1.4 times what is modeled).? This could also be used provide a negative bias voltage, though it's not much different from cathode bias.? Often called "back bias".? Definitely out of PSUD territory...
