Re: Museum Coil Revisited

To: tesla-at-pupman-dot-com
Subject: Re: Museum Coil Revisited
From: FutureT-at-aol-dot-com
Date: Thu, 2 Jan 1997 20:34:01 -0500
Subscriber: FutureT-at-aol-dot-com Thu Jan 2 23:15:06 1997
In a message dated 97-01-02 02:57:38 EST, you write:

<< 
 Subscriber: bert.hickman-at-aquila-dot-com Wed Jan  1 21:43:31 1997
 Date: Wed, 01 Jan 1997 10:38:36 -0800
 From: Bert Hickman <bert.hickman-at-aquila-dot-com>
 To: tesla-at-pupman-dot-com
 Subject: Re: Museum Coil Revisited
 
 Tesla List wrote:
 > 
 > snip
 > << > The relatively radical approach used by Cox caused me to take a
another
 >  > look at this aspect of coil design. It looks like Cox'es grounding
 >  > approach may be the best, at least for Museum coils!
 >  >
 >  > Isn't that the Oudin Coil scheme?
 >  >
 >  >                                                                 73, Ira
 >  >
 >  >" Yes, although there's some controversy over just _who_ should be
 >  credited with this configuration. There are some who would say that an
 >  "Oudin Coil" is also a minor variant of a Tesla Coil, and Oudin should
 >  not be credited for what is largely Tesla's work. The reason this
 >  configuration is somewhat "radical" today is that it goes against the
 >  conventional wisdom on how 2-coil TC's should be constructed from a
 >  safety and EMI standpoint, not that it is a brand new approach."
 > 
 > >Safe coilin' to you, Ira!
 > 
 >  -- Bert --
 >   >>
 > I've never used a separate ground for my secondary coil.  I always ground
one
 > side of my pri. tank, except in neon-sign systems.  I haven't had any
 > problems with arcing outlets, etc.  Never gave it too much thought since I
 > was busy with other coil aspects, but these posted comments are
interesting,
 > never realized this hook-up was so rare and disliked.
 > 
 > I thought also that capacitance between pri. and sec. was to be avoided as
an
 > operating loss?
 > 
 >    John Freau
 
 >You bring up an interesting point! I had "assumed" that the
 >configuration of tieing one end of the primary to the secondary was
 >relatively rare, based upon the excellent design guidelines that Richard
 >Quick and others have provided on the Tesla site or in previous BBS and
 >Tesla List postings. I think the main objection was one of safety - with
>the primary floating, there was no direct connection between any portion
> of the 60 Hz HV, or high-power primary RF section, and the secondary. If
 >the common connection to ground were to become open or degrade, there
> was at least less of a chance that the entire secondary would become
 >"live" with high voltage at 60 Hz. However, other bad things would
 >probably happen if you had an open the secondary base ground...
>BTW - do you ground the innermost turn or the tapping point?
 
> Primary-Secondary capacitance does not usually operating losses, unless
> you're overcoupled and seeing heavy corona breakout between the two.
> However, to the extent that higher capacitance effectively increases the
 >coil self-C or toroid capacitance, it can have the impact of reducing
 >coil output voltage a bit (all other things remaining the same). Is
 >there another loss you're thinkning of?
 
> Safe coiling to you!
 
 -- Bert --
>>
Bert, 

I ground the inner primary turn in the hope that this will help to prevent
corona, flashover, and losses.   The capacitive losses I refered to are the
ones you mentioned.  I suppose the separate sec. ground is safer.   BTW, what
is the TESLA  SITE that you mentioned?    BTW, I'll get the specifics from
Lou Balint concerning his oil-magnifier and oil tuning cap. 
Happy  Coiling!
 
    John Freau