Primary field strength

To: "'Tesla List'" <tesla-at-pupman-dot-com>
Subject: Primary field strength
From: Tesla List <tesla-at-stic-dot-net>
Date: Tue, 18 Aug 1998 23:51:55 -0500
Approved: tesla-at-stic-dot-net

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From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
Sent:  Tuesday, August 18, 1998 4:00 PM
To:  Tesla List
Subject:  Re: Primary field strength

Hi Chris,

> From:  chris.swinson [SMTP:chris.swinson-at-zetnet.co.uk]
> Sent:  Sunday, August 16, 1998 3:48 PM
> To:  Tesla List
> Subject:  Re: Primary field strength
> 
<snip>
> so if the field is that big, I could easily make a 200" secondary, as it
> appears the field is huge when the caps are included.  Ok, I could not do
> this as I only have 80" hight in my room.  But you see what I'm getting at.
> 
> This was only 1 gap as well, If I used all 5 gaps , the field would probably
> go 100's of yards away.  So what stopping me from building a bigger
> secondary ?

The problem can summarised thus: You are transferring a fixed amount 
of energy from the primary cap to the secondary capacitance with each 
gap fire. Each gap fire is separate from every other. There is no 
accumulation in the secondary with successive gap fires. The 
capacitance of the secondary rises with its size. 

Since Vo = Vgap*SQRT(Cp/Cs),  you can see what is happening to your 
output voltage as your secondary gets larger. Taken to an extreme, if 
your secondary capacitance ends up being as big as the primary one, 
secondary voltage only reaches that of the primary assuming no loss 
in effecting the energy transfer.

Malcolm    
<snip>