[sdiy] Guard Rings

[Harry Bissell]

I thought that too, but couldn't you put that resistor between the source of the FET and the base of the emitter-follower transistor and make life easier... ?

(unless you are worried about what might happen if the cap was holding a charge and you crowbar'd
the power supply suddenly....)

H^) harry

----- Original Message -----
From: Neil Johnson <neil.johnson97 at ntlworld.com>
To: Harry Bissell <harrybissell at wowway.com>
Cc: David Ingebretsen <dingebre at 3dphysics.net>, synth diy <synth-diy at dropmix.xs4all.nl>
Sent: Fri, 05 Nov 2010 11:02:14 -0400 (EDT)
Subject: Re: [sdiy] Guard Rings

Hi,

> I agree, what is R13 ?

My guess: it limits the peak current through the G-S junction
(remember, its a PN junction, so will conduct if forward biased).

But that's just a guess.

Neil
-- 
http://www.njohnson.co.uk

-- 
Harry Bissell & Nora Abdullah 4eva