I need some help to fully understand how this circuit works (credits to Audio Design Guide):
My doubts are in the operation of the MOSFET. I tried to gather some information from my books and online, and the summary of what I know about it is:
- R2, R3, R1, C1, R5, D1 and M1 work as something called a "capacitance multiplier"
- The above mentioned components work as a ripple filter
- The B+ Out voltage is determined by the R2 - R3 voltage divider.
- B+ Out takes circa 110 seconds to reach its maximum
From my understanding the ripple is minimized by the R1 - C1 lowpass.
What I don't understand is what the MOSFET does, how it operates. Can you give me a hint?