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From: thad@cup.portal.com (Thad P Floryan)
Newsgroups: unix-pc.general,comp.sys.att
Subject: Re: Brownouts, shorts, explosions and the unix pc.
Message-ID: <37881@cup.portal.com>
Date: 11 Jan 91 14:36:06 GMT
References: <1991Jan6.050124.6838@csn.org> <37644@cup.portal.com>
  <484@dmk3b1.UUCP> <1991Jan11.025038.11661@colnet.uucp>
Organization: The Portal System (TM)
Lines: 61

res@colnet.uucp (Rob Stampfli) in <1991Jan11.025038.11661@colnet.uucp> writes:

	>And for those electronics hobbiests amongst you, don't play with Tesla
	>coils within 400m (1/4 mile) of computers ... you WILL zap CMOS ICs.

	I am a ham radio operator.  I have gone to numerous hamfests where
	various individuals were actively operating tesla coils in order to
	garner interest in a potential sale of tesla coil kits.
	[...]
	I don't dispute that it is possible to zap a computer with a tesla
	coil, but why doesn't their use at these hamfests cause a major
	catastrophe?

Probably because the HAMs would jam the remnants of their handheld transceivers
down the throat of any clown with a really *B*I*G* Tesla coil!  :-)

Seriously, as with most other things, there are power differences amongst
different models.

Contrast a SONY Walkman to a 1000W Phase Linear audio amp.
Contrast a gas-operated leaf blower to the engine on the Space Shuttle.
Contrast a precision micro soldering pencil to a 500W soldering gun.

I've seen small, desktop (literally handheld) Tesla coils, and I've seen Tesla
coils from which I want to be more than a mile away when energized.  And
Popular Science had a picture of one circa 1980 that was over 75 feet tall ...
I don't even want to be in the same country when THAT one is fired up! 

The one the dealer had (re: surge suppressors and UPS systems) was about 4-1/2
feet tall (chest-high to me), and his insurance company "convinced" him not to
energize it any more at demonstrations due to claims of damaged computers.  We
did fire it up "one last time" in his parking lot; neat!  It's since been
dismantled.

High power "anything" will "do in" things.  I recall one incident that is
"rumored" to have occured either at Ft. Bliss TX (Air Defense School) or at
White Sands Missile Range circa late '50s or early '60s: a soldier took a
shortcut through the "beam" in a multi-megawatt RADAR installation and keeled
over, and it wasn't apparent what happened until after the autopsy: certain
internal organs were cooked.  This incident is "rumored" to have been the
start of what we today know as MicroWave ovens.  Though I was there at the
time, I don't have any first-hand information, but I also have NO reason to
disbelieve such an incident did occur.

The frequencies used in consumer-grade ovens "like" objects the size of
eyeballs and human testicles which is one of the reasons why, to this day, I
still don't have a microwave oven at home.

And before you pshaw-away my "fears", remember that one of my specialties is
microwave engineering with which I was gainfully employed at the Electronic
Defense Labs until I got involved with computers and a small "startup" known
as Tymshare Associates whose legacies today are Tymnet (now owned by British
Telecom) and McDonnel-Douglas Field Service Operations.

One final comment: power decreases with the square of the distance, which is
probably why a small Tesla coil at your HAM-fests doesn't perturb the other
equipment.  Even those huge electro-magnets that are used to lift cars have
little power to do so with just an inch or two separation (but, again, the
EMP-like effect of a Tesla coil cannot be compared to magnetism).

Thad Floryan [ thad@cup.portal.com ]