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Re: A few questions and comments

In a message dated 4/18/00 11:09:45 AM Pacific Daylight Time, 
tesla-at-pupman-dot-com writes:

> Original Poster: "Chris Brick" <cbrick-at-rebelbase-dot-com> 
>  
>  Question:
>  
>  I have found that a lot of people recommend a 3:1 ratio for secondary size 
>  and am wondering if there is point in which the ratio isn't as 
>  important.  Also, how important is keeping the number of turns between 800 
>  and 1000?  I am in the process of building a large secondary (6 to 8 feet 
>  long and as wide as necessary) and want to make sure I don't make it too 
>  long that the number of turns is higher than optimal.  I am using 17 gauge 
>  wire.

Chris,

The 3 to 1 ratio is possibly a little short in some cases, esp for a small
coil.  Generally smaller coils will have a higher ratio than larger ones,
but even that rule only applies sometimes.  I've used a secondary that
is 4" by 23" and compared it with a secondary that is 6" by 24", both
wound with # 28 awg wire.  Both secondaries gave the same results.
Bottom line, it's not that critical.

IMO, you're better off with more turns than less turns.  I've always 
gotten longer sparks using more turns than less.  For instance when
I used 660 turns, I got 38" sparks, but when I used 1500 turns I got
42" sparks.  but this was a small coil.  In a large coil, fewer turns may
be OK.  I'm not sure because I never made a large TC.  

I do think that a narrower coil is better than a wide one.  The narrow
coil will have less self-capacitance, which lets you concentrate the
capacitance in the topload where it belongs.  The narrow coil also
lets you use thinner wire, which is cheaper, the coil will be lighter,
easier to build and handle, etc.  Bottom line; all the advantages favor
a narrow coil.  Of course *too* narrow is NG either.

Regarding wire size, IMO coilers tend to use wire that is too thick,
I favor a somewhat thinner wire size than the average coiler.  The #17
you speak of seems like a good wire size to me.  Much depends on
how much power you plan to use, and what spark length you expect.

For instance Richard Hull used #18 wire on a 14" by 45" coil form or so,
and obtained 15 foot arcs, so his arcs were about 4 times longer than
the coil length.  If you're looking for arcs 4 times your coil length that
would come to 24 foot to 32 foot arcs which will require up to 40kVA 
or more.

Yes, this Tesla list is great....great people....great research  !!!

Cheers,
John Freau

>  
>  Does anyone know what materials Greg Leyh used to build his large, open 
air 
>  secondary (not the Electrum coil) ?
>  
>  Comments:
>  
>  I am very impressed with the quality of information that comes across this 
>  list.  Even though I have some trouble following the big math 
>  conversations, I learn something new every post and eventually will 
>  understand it all much better.
>  
>  Thanks,
>  
>  Chris
>