Cell phones and humans
Group, the subject of possible biological effects of cell phones is having a lot of attention these days and it was already touched in this forum. I'd like to get opinions about what my wife just told me. I don't know if this should be classified as "influence of cell phones on humans" or "influence of humans on cell phones". The story is as follows: my wife was talking on her cell phone while walking by a swimming pool. As she steppen right on the wet border of the pool (she was bare foot) the line went down. But just after stepping back on dry ground (just a step or two back, so the signal level shouldn't have changed so much) the line got back and she was able to resume her conversation. She told me she didn't step back again on the water, just to check if the phenomenon was repeatable. I honestly don't know if this is even worth of attention because of course it's not a "laboratory" or just even a "controlled" experiment. But if anyone out there has any guess or thinks there is an explanation... that would be welcome !! Paolo --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
EFT/Burst
Group, we are currently discussing with one OEM the interpretation of EFT/Burst test requirements per EN55024 and EN61000-4-4 to a printer. Specifically we are discussing the requirements of application of bursts to AC power lines. Our understanding is that they must be applied between each (single) power supply conductor and reference ground (or protective earth), as specified in EN61000-4-4 section 7.3.1. Also fig.4 and fig.11 in the same document seem to confirm this. Our OEM customer says that all combinations of phase, neutral and protective earth should be tested. They actually tested both singular AC lines and also more than one AC line. The printer passed the test in the first mode and failed in the second mode. Any comments / interpretations would be highly appreciated. Paolo Roncone Compuprint s.p.a. Italy --- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson:pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
RE: Charge moving from decoupling capacitors
George,
can you pls explain your correction ?
I supposed your first statement ("At 1/4 wavelength, the charges are 90
degrees out of phase") was the correct one !
Paolo Roncone
Compuprint s.p.a.
Reply Separator
Subject:RE: Charge moving from decoupling capacitors
Author: george_t...@dell.com
List-Post: emc-pstc@listserv.ieee.org
Date: 5/22/00 9:14 PM
Barry,
I need to make a correction. I was rushing to lunch on Thursday, so I
did
not read over what I wrote. Here is the correction for the 2nd comment
below:
At 1/4 wavelength, the charges are 180 degrees out of phase, so they are
working against the IC current draw. 1/8 wavelength (90 degrees out of
phase) is what I consider to be acceptable.
Regards,
George Tang
george_t...@dell.com
-Original Message-
From: Tang, George
Sent: Thursday, May 18, 2000 12:31 PM
To: 'Barry Ma'; Tang, George
Cc: si-l...@silab.eng.sun.com; emc-p...@ieee.org
Subject: RE: Charge moving from decoupling capacitors
Barry,
Thanks for the comments. Here are my comments:
Ok, you put caps at a certain distance away from the IC because you only
want them to work at 100 MHz. But that distance turns out to be the 1/4
wave distance at 400 MHz, and you placed enough caps at the 1/4 wave
distance to cause board resonance. Now what? Do you tell the caps not
to
work at 400 MHz because it's not their frequency?
For your 2nd comment:
I used the words "loosely define" for that reason. If you are
interested in
high frequency decoupling and instantaneous current, you really want to
have
all your charges moving in phase. At 1/4 wavelength, the charges are 90
degrees out of phase, so they will not do much for your instantaneous
current. 1/8 wavelength is what I consider to be acceptable. You can
certainly pick a different number.
Regards,
George Tang
george_t...@dell.com
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