[Milsurplus] FET Regulator: How It Do Dat?

[Hubert Miller]

Make that, the 18 volt zener only  conducts when source is 18 volts less than gate ( limiting the FET gate bias to +18 volts approx. )
( This would also provide some protection against the inrush current for the following capacitor. ) 
-H 

-----Original Message-----
From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Hubert Miller
Sent: Monday, April 3, 2017 4:33 PM
To: milsurplus at mailman.qth.net
Subject: Re: [Milsurplus] FET Regulator: How It Do Dat?

I ain't so smart, but looks to me that the MOSFET the drain and gate voltages add to bias the gate in either conduct more - conduct less condition. 
The 18 volt zener only conducts when S  is 18 volts lower than the drain. That's a form of current limit protection in case the output suffers some serious lowering of joltage, like a high current drain.  Looks like to me. 
-H