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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
> > >
> > >
> > >
> > >
> >
> >
> >
>
>
>