Re: Planning a magnifier

[FutureT-at-aol-dot-com (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

In a message dated 7/18/00 9:16:32 PM Pacific Daylight Time, tesla-at-pupman-dot-com 
writes:

> Some coilers claim that good homemade plastic bottle capacitors
>  work almost as good as the commercial caps - even in magnifier coils - 
>  while others insist that commercial caps are the only way to go in a
>  magnifier setup.  I am looking for a cap that will perform reasonably
>  well, without requiring that I blow hundreds of dollars in addition to
>  what I am already paying for my pig.  Does anyone know of a capacitor
>  type that would be good for me?  I guess the capacitance sort of depends
>  on the power of my input transformer, but the pigs are all rated at
>  24,940 V.  Sorry if I'm asking too many questions, but any help would be
>  much appreciated.
>  
>  Thanks!
>  
>  Joshua Wilson
>  

Joshua,

I've never tried plastic bottle caps, but rolled poly caps will perform
about the same as commercial caps, if the rolled poly caps survive.
Probably the best type of homemade cap is an MMC cap made up
from individual small polypropylene caps soldered together, but this
can get somewhat expensive if you're on a budget.

There's nothing about a magnifier that demands a different type or
quality of cap than a normal TC, because a magnifier works very similar
to a normal TC despite what you may have heard.  There are a lot
of myths about magnifiers such as that they give better performance,
need better caps or spark gaps, utilize very tight coupling, etc.  This
is all false.  The latest research and analysis by others and myself
show that the performance is the same as a normal TC,
and the coupling is about the same as a normal TC.  It is only the
primary to driver coupling that is tight, but the overall coupling
(which is what matters) is loose.  Because of this, just a normal
spark gap is needed.  Any cap that works well in a normal TC will
work fine in a magnifier.  The best way to think of a magnfier is as
a normal TC that has it's resonator cut into two pieces (that's 
oversimplified a little, but is generally correct).

There may be a way to get a little more performance from a 
magnifier which is described at Antonio's webpage, but this has
never been demonstrated in a working coil.

Those pig voltages you mention are pretty high, usually the 14.4kV
is more common.  You may have to take extra precautions with the
higher voltage.  I would go for the larger size pig for scaling up later
as you said.

Cheers, and be safe,

John Freau