On 12/31/2010 7:39 AM, Spehro Pefhany wrote:

 > For more protection, add to Olin's clamp a back-to-back pair of 500V
 > depletion-mode MOSFETs in series with "SIGNAL". Such a circuit can
 > handle 277VAC connected directly to the input.

I'm starting to like this protection circuit....

But, can you clarify which back to back arrangement we're talking=20
about?  Probably because my brain is so polluted with Enhancement fets...

And, I'm assuming you mean N-channel Depletion, since it seems P-channel=20
depletion isn't very common...

-forrest

--=20
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