Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!rutgers!princeton!allegra!ulysses!sfmag!sfsup!dcm
From: dcm@sfsup.UUCP
Newsgroups: sci.electronics
Subject: Re: Tesla Coil (**RETRACTION**)
Message-ID: <981@sfsup.UUCP>
Date: Mon, 15-Dec-86 11:41:25 EST
Article-I.D.: sfsup.981
Posted: Mon Dec 15 11:41:25 1986
Date-Received: Wed, 17-Dec-86 20:17:35 EST
References: <4815@reed.UUCP> <823@A60.UUCP> <824@A60.UUCP> <904@sfsup.UUCP> <675@uwmacc.UUCP>
Reply-To: dcm@sfsup.UUCP (David C. Miller, consultant)
Organization: AT&T Information Systems, Summit N.J.
Lines: 66


	+----------------------------------------------------------+
	| ***DON'T BUILD A TESLA COIL WITHOUT CHECKING THE FACTS** |
	|		(Do as I say, don't do as I did!!)	   |
	+----------------------------------------------------------+

In article <904@sfsup.UUCP>, I wrote that
it was possible to build a tesla coil without a spark gap or capacitor.
In article <675@uwmacc.UUCP> pwu@uwmacc.UUCP (Peter ) replied:
>
>If he did that he'll blow out the fuse or the neon transformer in no
> time.
>Imagine shorting the output of a neon transformer (~1000 V) to the
>primary of the tesla coil (several feet of wire loop around air is as
>good as short circult to 60 Hz AC).
>
>Maybe I am wrong; someone ought to try this out :)
		   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  NO! NO! NO! NO!

Having been properly chastized (sp?), I wish to withdraw those statements.
I did this some years ago as a freshman in college and it did work.
Lovely sparks and such.

Fortunately, it seems someone up-stairs must have looked
favorably on me and I'm still around today.  (The secondary
started arcing with one of the primary windings and
burned through it before I could get it turned off!  WHEW!)

What I built was not a tesla coil, but a bodacious spark coil.
Had I caught one of those lovely sparks it would have been hacker flambe'e.

What follows is from of one of the letters I received.
(This is real scary reading, looking back on what I did!! 8-< )

This one from tweed@apollo.UUCP (David Tweed):
+-------->
|
|   !!!! ATTEMPTING TO BUILD A 60-HZ TESLA COIL IS INCREDIBLY DANGEROUS !!!!
|
|   True Tesla coils operate a a frequency of several megahertz (check one of
|the many suggested references for the actual range). This makes the sparks
|that are generated travel over the surface of, rather than through, the human
|body, making them essentially harmless.  This effect is known as the skin
|effect.
|
|   The purpose of the primary spark-gap in the Tesla coil is to provide lots
|of high-frequency energy from the 60-Hz transformer (it arcs on each peak of
|the power waveform, essentially). This energy is filtered by the resonant
|circuit formed by the inductance of the primary of the Tesla coil and the
|discrete capacitor. It is only this (safe) radio-frequency energy that gets
|boosted by the secondary of the Tesla coil.
|
|   All parts of the primary circuit should be treated as extremely dangerous,
|as there is plenty of 60-Hz high voltage floating around, which is what is used
|in electric chairs (just so you get the right mental image).
+-------->

Please be careful.  I survived my experiment, others might not.  

David C. Miller, consultant
AT&T Information Systems
190 River Road
Summit, NJ  07901
(201) 522-5149

{allegra,burl,cbosgd,clyde,ihnp4,ulysses}!sfsup!dcm