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RE: Secondary size



Original poster: "Luke" <Bluu-at-cox-dot-net> 

Ok so 2" would be a bad idea.
4 6 8 or even 10 would be better.
Why not go with a 24" dia coil?
With a 15KV 60mA NST and a rotary spark gap I should be able to get some
huge sparks from a secondary that gives even more performance because it
is a 24" dia. right?

Comon sense tells me this would be nuts.
But the question is WHY?
If 6 is better than 2 then 50 must be better than 6 right?
Where do you stop on how large to make the dia?

I have had the idea that the larger your dia the larger your top load
would need to be to shadow the secondary.  This large top load would
have a high capacitance so it would work against output because of the
capacitance ratio.

If the sec dia should be bigger, how much bigger? And WHY?

Luke Galyan
Bluu-at-cox-dot-net

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, January 15, 2004 7:18 AM
To: tesla-at-pupman-dot-com
Subject: Re: Secondary size

Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>


At 60 mA you should not run a 2" dia. coilform.  Even 4" reduces
performance.

If you're running 60 mA you could use a 6 " ID, 8" ID, or 10 " ID
coilform
with much greater output.

Your resonant cap value would be 10.6 nF (.0106 uF).  This is, of
course, a
value you really don't want to use or potential resonant rise could
occur
and blow your NST.

If you are running a stationary sparkgap your correct value would be 1.6
x
resonant value, ie, 1.6 x 10.6 nF, or approx 17 nF (.017 uF).  This
keeps it
above the resonant range and keeps your NST safe.

Now, if you opt to go for max power, then you run a synchro RSG.  Use
the
10" ID coilform.  Your multiplier then becomes 3.2 x resonant value, ie,
approx 34 nF.  This sounds like a lot of capacitance but remember your
NST
is not trying to charge it 2-3 times per 1/2 cycle, only once.  Sparks
at
4.25 ft with this setup.

Dr. Resonance

Resonance Research Corporation
E11870 Shadylane Rd.
Baraboo   WI   53913

  >  > I know 4.5:1 works very well.  Since this is true I could then use
my
  >  > 15KV 60Ma NST, give it a SRSG and a MC of .028 micro farads.  Then
my
  >  > optimal coil height would be 9" tall right?  Providing I use a
secondary
  >  > dia. of 2" I would still be in the 4.5:1 ratio and poof I should
fall
  >  > into a good rule of thumb for my coil height.  I got it!  Thanx!
  >  >
  >  > Ok that was not meant to be sarcastic.  I was trying to show you
that
  >  > the ratio was not my question as stated in the original question.
There
  >  > were actually a few questions I had.  but in reference to the one
you
  >  > answered I was aiming somewhere else.
  >  >
  >  > Assuming I use your recommended 4.5:1 ratio.  What is a good
height to
  >  > use based on the anticipated arc length?  Obviously the 9" tall
coil
  >  > might have some problems if say 50" arcs were created.
  >  >
  >  > The question is based on a particular anticipated arc length, what
is a
  >  > good rule of thumb to decide on the HEIGHT of the coil?
  >  >
  >  > After I get this under my belt ill re ask the other questions.
  >  > Thanx
  >  >
  >  > And again I do not mean to sound sarcastic just trying to make a
point
  >  > in order to address my real question.
  >  >
  >  > Luke Galyan
  >  > Bluu-at-cox-dot-net
  >  >
  >  > -----Original Message-----
  >  > From: Tesla list [mailto:tesla-at-pupman-dot-com]
  >  > Sent: Tuesday, January 13, 2004 9:01 PM
  >  > To: tesla-at-pupman-dot-com
  >  > Subject: Re: Secondary size
  >  >
  >  > Original poster: "Dr. Resonance" <resonance-at-jvlnet-dot-com>
  >  >
  >  >
  >  > An optimum coil height to dia ratio is approx 4.5:1.  At values
less
  >  > than
  >  > 4.5:1 arcing to primary or strike rails occur on a regular basis.
If
  >  > the
  >  > coil is too high the coeff. of coupling is lower and less energy
is
  >  > transferred.
  >  > 4.5 : 1 seems to work very well.
  >  >
  >  > The potential output of a resonance transformer is equal to it's
gain
  >  > times
  >  > the potential input, ie,
  >  >
  >  > Vout = Vinput peak (1.4 x Erms) x sqr (Ls/Lp)    ----    this is
called
  >  > system gain.
  >  >
  >  > Also inductance of a coil is proportional to n^2 (high number of
turns
  >  > works
  >  > good because of this square factor) and also to r^2 (this is the
radius
  >  > of
  >  > the coils geometry).  This r squared factor rapidly increases the
  >  > inductance
  >  > (Ls) in big coils so the gain (voltage multiplication factor) is
high
  >  > and
  >  > output potential is high.
  >  >
  >  > It's important to note that spark length is more of a function of
  >  > current
  >  > (system power) than potential.  To double the spark length in most
  >  > systems
  >  > the power has to be increased by a factor of 4 (2 ^2).
  >  >
  >  > Hope this answers your question.
  >  >
  >  > Dr. Resonance
  >  >
  >  > Resonance Research Corporation
  >  > E11870 Shadylane Rd.
  >  > Baraboo   WI   53913
  >  >   >
  >  >   > I would assume that the height would be based on anticipated
arc
  >  > length
  >  > and
  >  >   > the dia would simply fall into using what you can to stay in
the
  >  > suggested
  >  >   > height to width ratio.
  >  >   > How do you go about deciding how tall the coil should be based
on
the
  >  > arc
  >  >   > length?
  >  >   > Other than aesthetics what is the method for choosing a
secondary
  >  > size?
  >  >   > What is the cut off for deciding how short a coil can be with
a
given
  >  >   > anticipated arc length?
  >  >   >
  >  >   > It seems there are coils that generate longer arcs than the
coil is
  >  >   > high.  And since the arcs are referenced to ground it seems
that is
  >  > putting
  >  >   > the top load very close to ground with respect to its output.
I
know
  >  > that
  >  >   > the toroid slash secondary top will be at the same positive or
  >  > negative at
  >  >   > any one time as the arc and like charges repel so that is what
keeps
  >  > the
  >  >   > arcs from going straight down.
  >  >   >
  >  >   >
  >  >   > Ok also if a height is determined what are the advantages /
  >  > disadvantages
  >  >   > for going with the larger diameter coil verses the smaller
diameter?
  >  > Keep
  >  >   > in mind that when I say large or small diameter I am talking
about
  >  > staying
  >  >   > close to the excepted rule of thumb for height to dia. ratio.
  >  >   >
  >  >   > Thanx
  >  >   >
  >  >   > I will be asking lots more questions so bare with me.  J
  >  >   > Luke Galyan
  >  >   > Bluu-at-cox-dot-net
  >  >   >
  >  >   >
  >  >   >
  >  >   >
  >  >
  >  >
  >  >
  >
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