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From: wolfgang@mgm.mit.edu (Wolfgang Rupprecht)
Newsgroups: sci.electronics
Subject: Re: And you thought you've heard everything!
Message-ID: <1718@bloom-beacon.MIT.EDU>
Date: Fri, 30-Oct-87 14:33:49 EST
Article-I.D.: bloom-be.1718
Posted: Fri Oct 30 14:33:49 1987
Date-Received: Wed, 4-Nov-87 22:37:50 EST
References: <9312@tekecs.TEK.COM>
Sender: daemon@bloom-beacon.MIT.EDU
Reply-To: wolfgang@mgm.mit.edu (Wolfgang Rupprecht)
Organization: Independent Software Consultant
Lines: 60

In article <9312@tekecs.TEK.COM> snoopy@doghouse.gwd.tek.com (Snoopy) writes:
> [ a quote from Peter Belt from _Hi-Fi_Answers_ ] 
>  "The answer turned out to be simple: leaked energy from the AC mains supply.
>  This was having the effect of ionising the air which in turn created a
>  complex network of charge potentials across the surface of conductive
>  objects.  The presence of stray electromagnetic fields interacting with 
>  this leaked AC field seemed greatly to increase the ionising effects,
>  thereby worsening the sound."

Well, Peter does sound like he has a great career ahead of him. Is he 
into radio communications with the dead also? ;-)

Seriously, I have told of reports about exposure to various
electrically induced fields.  The claim is that large ion flows, and
large ac magnetic fields as by power-lines, both effect you slightly,
but in entirely different ways.

The claim is that large ion flows (ie. from a terminal that has a
cheap *very* non-conductive screen), will "bathe" you in this flux.
This has the effect of sticking charge on facial hairs, insulating
skin flakes etc. No ill effects come from this charge directly (the
human body is *quite* conductive, once you get past the insulation of
the skin's outer surface). The effects come from: 1) the negatively
charged particles (ie. including half of the smoke, dust and dirt in
the world) that is constantly flowing away from the screen, being
repelled by the ions which are also moving away, and 2) the positively
charged particles (the other half of the smoke, dust and dirt) that
also get stuck to your skin, after being attracted by the negative
charge just stuck there, and trapped in the surface oils, etc.
Luckily the two effects tend to cancel out each other.

So is that why comp-u-nerds have most of the world's supply of acne? ;-)

I have seen quite a range of surface charges on various CRT screens.
The old VT-100, that I had once, worked better than most electostatic
air cleaners. I never needed a glare-guard for that. It attracted its
own (self healing) matte-surface. Other terminals don't even make the
finer hairs on the back of your hand stand up when you hold your hand
near the screen. (Actually, a conductive spray, as used to protect
CMOS work environments, would probably work wonders for cheap crt
screens.)

On ac magnetic fields: 

I heard a bit on NPR a few months back about a high tension power line
study. It claimed higher levels of stress on subjects exposed to 60hz
magnetic fields for long durations. They went on to say that strong
e-fields (such as found near high voltage lines) had no noticable
effects. I'm not sure how one can verify "stress levels". What does
ring true about it is that the human body does have quite a low
impedence internally.  Any exterior e-field would be attenuated
(inside the body) by the ratio of the air's resistance to the body's,
a very large number to be sure. This same low impedence makes it easier
to induce small currents by alternating magnetic fields.

Now, how does this effect Peter Belt's stereo? Well, if Peter lived
near both a high tension power line, and a cheap terminal manufacturer
... ;-)
Wolfgang Rupprecht	UUCP: mirror!mit-mgm!wolfgang
			ARPA: wolfgang@mgm.mit.edu (IP addr 18.82.0.114)