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