[Amps] Novel Screen Grid Regulator

[Carl]

Ive been using the IXCP0M90S, good to 900V at 1-100ma. Keeps those sensitive 
screen grids safe from over current or collateral damage when there is an 
internal failure.

It does keep 8122's happy in my case.

Carl

----- Original Message ----- 
From: "Paul Christensen" <w9ac at arrl.net>
To: <amps at contesting.com>
Sent: Thursday, September 27, 2012 12:52 PM
Subject: Re: [Amps] Novel Screen Grid Regulator


> Jim,
>
> Very interesting circuit since the MOSFETs function like a high-power, 
> active voltage divider.  I did note that the non-inverting input to U1a 
> may be susceptible to the effects of both the normal screen voltage and 
> perhaps a flash from the screen.  However, provided that Z1 acts quickly 
> enough and R10 remains intact, then concern is probably minimized.  Still, 
> it may make sense to Zener-clamp the non-inverting op-amp input to a level 
> just above the value found in normal operation.  Then, if adding 
> Zener-clamping, I think it would be a good practice to add series R at the 
> non-inverting input of 1K.  The input Z to the non-inverting input of the 
> LM358 is quite high, allowing for some additional series R protection.
>
> Paul, W9AC
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