Question about diode clamper
Assume negligible resistance for the Diode On resistance of say 1 Ohm per Amp and ESR of Cap of 1 Ohm per 100uF and is much smaller than RL. 

Assume the impedance of the Cap is &lt;&lt; RL at some frequency and uF

Then the Diode only turns on at the 1st half cycle and then only at just before sine peaks when diode restores charge drained slowly from RL.

Otherwise the Diode is OFF and the Cap has a stored DC voltage to pass AC thru to load. 

Thus you have an "AC passthru with DC clamp" either positive or negative. 

There is an offset due to the diode drop when ON.
Better "Active Clamps" overcome this offset with a FET switch during peak zero crossing using dV/dt=0 for either positive or negative peak signals.

e.g. TV Video Hsync uses an Active Clamp to restore AC coupled video to DC = 0V = "Black Level" after sync pulse.