Re: Larger secondary more efficiency?

["Albert Hassick" <uncadoc-at-juno-dot-com> (by way of Terry Fritz <twftesla-at-uswest-dot-net>)]

Hello!  I think the 12" sonotube will work very well with the power
supply you have.  I have noticed that a larger, fatter secondary gives me
lots of sparks.  The tall skinny coils I started the hobby with do not
give out much spark.  I think a short fat secondary will give excellent
results!    Lately, I have tried to follow the "pi" formula with respect
to coil width in relation to coil height, and it works great!  Don't ask
me why since I know nothing about math.  I just decided to use the "pi"
formula and it worked!  So I am now prepping a 12" diameter x 37" high
tube at this time.    I have the same supply that you have, except mine
are modified/shunt removed neons that have been unpotted.  I am now
myself prepping a 12" sonotube with many coats of polyurethane on the
exterior and fiberglass resin on the interior of the tube.  I use many
coats of sealer because I run my coils for very long periods of time and
I do not wish to see them carbon track.   I must be doing something right
, since I can run a cardboard sonotube for over an hour at full power
with no destruction of the secondary.  So be sure to seal your tube the
best that you can.  My latest sonotube to date is a 8" x 25" high coil
and it is very nasty!  60" sparks are easily obtained.  I used #18ga.
wire on my 8" secondary and have found that the larger wire size = bigger
sparks. At least, that is the way it seems, since my first two coils were
wound with 23ga. wire and they did not give much output. but, they were
also of a very skinny diameter.  I think a fat tube with your 24ga wire
will work real well.  You will have a very successful coil!  If at all
possible, you may try to scout around and try to find a larger tube for
your primary, your 3/16 tube will certainly work, but I think you will
get more bang from your coil with a larger scale tube.      AL. 


On Sun, 08 Oct 2000 21:49:07 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> Original poster: "Kelly & Phillipa Williams" <kellyw-at-ihug.co.nz> 
> 
> Hello all,
> 
> I need some advice on materials.
> (Living in New Zealand, materials are difficult to find.)
> 
> My power supply is 15kV -at-120mA, and
> I have a large amounts of 24AWG magnet wire 
> and 3/16 inch copper refridgeration tubing.  
> 
> I would like an 8" or larger secondary, to increase efficiency,
> but over 6 inches PVC pipe becomes too expensive for me.
> I asked around about cardboard tubes equivalent to sonotube, 
> (for forming concrete columns) but all I can obtain 
> is 300mm OD tube, (that's 11.8 inches). - BTW this is cheap.
> 
> With 120 mA of current, can I use that large a secondary?
> (It's all I can get )
> I have heard that larger coils are more efficient, but surely
> there is a cut off point where efficiency starts to drop as coil 
> forms
> get larger?
> 
> Thanks in advance,
> 
> Alan Williams
> 
> 
>