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RE: Non-tiger question

To: "'Scott Hutchinson'" <shutchin@netjets.com>, <tigers@autox.team.net>
Subject: RE: Non-tiger question
From: "Stu Brennan" <stubrennan@comcast.net>
Date: Sat, 11 Feb 2006 14:18:16 -0500
Netjets.  Airplanes.  I should have guessed.  You mean those zillion
buck Citations and Hawkers don't have 60Hz converters?  What are those
poor executives to do?  Have any of them complained about fried laptops?

Anyway, I popped open a Dell power pack and here's what I found.

They first have a full wave bridge that rectifies the incoming AC into a
400V cap.  I read about 160V DC across it, which is about the peak of
the 110V AC waveform, so that makes sense.  This DC then appears to go
to a switcher type regulator that converts the power down to the laptop
input voltage.  Lots of electronics, mostly surface mount stuff, there.
The power packs I have interfere with the TV when placed nearby, another
symptom of a switcher, so I'm fairly confident about that. 

The switchers I worked with at my last company could accept a wide range
of DC input, so that explains why the power pack can accept such a wide
range of AC inputs...220 VAC would put about 312V across this cap, well
below the 400Max spec.

Anyway, I'd guess that the input rectifier would probably be OK at 400
Hz, and once you have the 160V DC, the rest of the circuit wouldn't
care.  So my guess is that it would probably work normally at 400Hz.
I'd feel the power pack once in a while, especially near the power input
end, just to be sure nothing is getting unusually hot.

All the usual disclaimers about YMMV, the above is based on the
examination of one power pack for maybe 5 minutes, use your own
judgment, this is just my guess, this could be wrong for your
application, etc.!!!!


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