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Path: utzoo!mnetor!seismo!lll-crg!lll-lcc!ptsfa!nonvon!apn
From: apn@nonvon.UUCP (apn)
Newsgroups: sci.electronics
Subject: Re: Tesla Coil
Message-ID: <1298@nonvon.UUCP>
Date: Sun, 14-Dec-86 23:43:24 EST
Article-I.D.: nonvon.1298
Posted: Sun Dec 14 23:43:24 1986
Date-Received: Wed, 17-Dec-86 04:19:12 EST
References: <4815@reed.UUCP> <823@A60.UUCP> <824@A60.UUCP> <904@sfsup.UUCP>
Organization: NONVON Systems Computer Research Group
Lines: 58
Summary: Wrongo..

In article <904@sfsup.UUCP>, dcm@sfsup.UUCP (David C. Miller, consultant) writes:
> >
> >Gene did forget one very important item.  As a series resonant LC circuit,
> >you need a capacitor.  this is placed in series with the neon sign xfmr
> >secondary, the spark gap, and the Tesle coil primary.
> >
> >[ description of capacitor ]
> 
> Not necessarily.  In fact, I would hazzard a guess that Gene could have
> omitted the spark gap as well and it would have still worked.
> 
> Spark gaps and capacitors are there to accumulate a charge, then release
> it through the primary in one large burst; much like the capacitor and
> point in a car.  The difference is that the circuit that Ron is
> referring to is strictly for DC power, Genes is for AC.  Yes, those
> neon sign transformers put out AC, so you really don't even need the
> sparkgap.
>

	A spark gap is almost mandatory in either circuit! You should
examine the rich RF spectrum emitted  from any electrical spark. This
is exactly what is needed to drive the primary of the final transformer
in a tesla coil. 10 or 20 turns should do. The sec. should be several
1000 turns.

	Also, let me point that if one does use 60hz power WITHOUT 
a spark gap, you can still obtain a rather high voltage. Although
nowhere near as high, since usually the final xformer is only air 
coupled and typically does not want to have any core material.

	Further, on using 60hz, you create a highly hazardouos HV 
on the output. 60 hz will not travel on your skin surface for example,
while 20mhz will. This has to do with eddy current effects and 
surface propogation waves.

	Of course one way to omit the spark gap is to use a 
simple oscilator circuit... but last I checked 1000W of 10kv drive
does not come in a nice small MOSFET package ( joke , ok ? ) So 
we are stuck using expensive transmitting tubes...



further clarifaction/obfuscation on request.


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