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Primary field strength




----------
From:  th3 mAst3r [SMTP:menthol-at-juno-dot-com]
Sent:  Sunday, August 23, 1998 4:53 PM
To:  tesla-at-pupman-dot-com
Subject:  Re: Primary field strength

this post is a little old but my comment is at the bottom.


On Thu, 20 Aug 1998 23:15:22 -0500 Tesla List <tesla-at-pupman-dot-com> writes:
>
>----------
>From:  Malcolm Watts [SMTP:MALCOLM-at-directorate.wnp.ac.nz]
>Sent:  Thursday, August 20, 1998 3:56 PM
>To:  Tesla List
>Subject:  Re: Primary field strength
>
>Hi Chris,
>
>> From:  chris.swinson [SMTP:chris.swinson-at-zetnet.co.uk]
>> Sent:  Wednesday, August 19, 1998 8:58 AM
>> To:  Tesla List
>> Subject:  Re: Primary field strength
>> 
>>  Hi Malcolm & All.....
>> 
>> 
>> 
>> >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.
>> >
>> 
>> I'm not 100% sure of what you getting at.  Are you saying that if I 
>did
>> build a 200" high seconday and ( theory ) had the same capacitance 
>as my 36"
>> seconday, it would in fact give me a huge power increase ?
>
>It won't have the same capacitance - it will be a *lot* higher which 
>means output voltage will be a lot lower for a given primary energy.
> 
>> 
>> >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.
>> >
>> 
>> 
>> Could you explain your calc a little better, Perhaps with a example 
>or 5.
>
>It is derived from Conservation of Energy. 
>
>    0.5CpVp^2 = 0.5CsVs^2   where Vp = gap firing voltage
>
>=>  Vp^2*Cp/Cs = Vs^2
>
>=>  Vp*SQRT(Cp/Cs) = Vs
>
>In other words, you can't get more out than you put in and that 
>equality assumes no losses in transferring the energy from primary to 
>secondary. Note that it also works by Vs = Vp*SQRT(Ls/Lp) since
>LsCs = LpCp (tuning requirement).
>
>Malcolm 
>
>
>

why is LsCs = LpCp a tuning a requirement?  does this mean most tesla
coils are double tuned transformer circuits or am i getting things mixed
up?

thanks...

~m3nthol

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