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Re: more cap questions



In a message dated 4/24/99 2:29:21 AM Pacific Daylight Time, tesla-at-pupman-dot-com 
writes:

> Original Poster: Robin Copini <rcopini-at-merlin-dot-net.au> 
>  
>  Is there a limit to a LTRC cap?,
>  
>  i.e. if the maths dictates a 0.083uf cap for my 5kva piggy - and I have
>  been advised not to design for resonance with the cap. Other posts to
>  this list  have suggested going LTRC, if this is so, bearing in mind I
>  am halfway through constructing an async RSG, just how much larger than
>  resonance can you go?, And, what is effected if you go larger? i.e.
>  chnages to tapped turns/freq of primary?
>  
>  
>   Regards
>  
>   Robin Copini,
>   Adelaide, South Australia.
>  
Robin,

I am using a 5kva distribution transformer on my 6.0" coil.  It was 
originally designed to use a .025 ufd primary tank cap.  I have since added a 
second .025 cap for a total of .05 ufd.  A larger cap will allow the system 
to process more power, thus longer sparks.  Adding more capacitance reduces 
the frequency so you have to use fewer turns on the primary.  But now you 
have more power, can make the toroid larger, which lowers the frequency of 
the secondary and moves the tap back out some on the primary.  It is not 
necessary to design for resonant charging with a transformer of this size.  
You will have plenty of current to charge the cap for multiple breaks per 
half cycle.  In fact, I had a primary 60 hz resonant problem for a long time 
with this system and blew two commercial caps by having basically an 
uncontrolled primary voltage rise in the system.

Ed Sonderman