My question is based on the MOSFET circuit shown in a question by uMinded.. "High Voltage Series Pass Transistor - Low Voltage Control" here
This circuit is a little unique in that it is not using a follower type load driver.. if you Google power supplies, 99% use an source- or emitter-follower based design driving the load..
My question is: yes a follower MOSFET or BJT has high current gain with no voltage gain and is simple, but adding a varying value of load capacitance and the error op-amp circuit becomes very unstable as the op-amp see's this capacitance on its output. So, why is the load, NOT Usually driven as it is in the circuit mentioned above (from the Drain or Collector) more isolating the op-amp from load capacitance... after all the op-amp has lots of gain.
I have simulated the circuit mentioned above with appropriate changes, and even when varying the load capacitance from 1 µF to 10000 µF it showed no sign of instability.