RE: H/D ratio

["Tesla list" <tesla-at-pupman-dot-com>]

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

Thanx
I know things are inter related.  Changing one thing changes another and
so on.
Maybe I have failed to make myself clear.
I am not looking for an exact science.  But if you tell me there is a
trade off in things is it too much to ask what trade offs are at stake
and give an explanation as to what trade offs affect what?  Most of what
comes down the pike is either someone saying well its just a big mix.
Or someone saying just do this.  Rather it be formula's or observations
or what ever there has to be some sort of majority opinion as to why the
rules are there.  Most just tell you the rules.  It is like they them
selves are in the same boat I am in.  They have no clue.  They just did
it because they were told the same rule they are telling me.

I can tell you a car is not fast enough for a race.  I am not a mechanic
so if you asked me why I could not explain the effects of torque vs gear
ratios or how much a different fuel mixture would effect the speed.  But
if you ask a mechanic who is into making cars go fast he could tell you
what can be done and why even if what he is telling you is disputed by
other mechanics.  At least he has his own theories on it.  I was hoping
to find some mechanic in this list.  And indeed I have.  But the
majority seem to just be quoting the rules the mechanics have given
them.

Luke Galyan
Bluu-at-cox-dot-net

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Friday, January 16, 2004 5:17 PM
To: tesla-at-pupman-dot-com
Subject: RE: H/D ratio

Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com>

The choice of secondary size, wire size, top load size, aspect ratios,
input power, and almost everything else is all interrelated and as with
most things, is a trade off between several problems.  For one to ask
for a
concise answer to all of this is unrealistic.  Some aspects of these
choices are only marginally understood, and to summarize all that is
known
about optimizing all design aspects, even if we could come to an
agreement,
would take more time and bandwidth than are available.

For the 900W 2" W x 9" L secondary - how long do you think the sparks
will
be coming off the top will be?  Most with similarly powered coils report
at
least 1-2 feet, often more.  I would suggest something longer than 9".

If you had a 50" diameter coil, what would be the total secondary
capacitance?  The higher the Csec, the lower the peak secondary voltage
would be.  And a large top load would require a higher breakout voltage,
so
it's unlikely you'd get breakout to occur.

There is no formula for choosing the optimal middle ground between these

examples.  They both fail for different reasons.  The middle ground is
obviously good because the extremes won't work.  The best one can to is
try
what has worked for someone else, and experiment further.  This is what
makes this hobby so much fun - if this were an exact science, we'd all
have
identical coils.  Where's the fun of a race if everyone runs the same
speed?

Choosing absurdly large and small wire diameters and numbers of turns
will
also lead to designs which won't work for a different set of
reasons.  You're not going to learn all of this at once, so be patient
and
read the List archives - quite a lengthy task!  In the meantime, you're
going to have to accept some advice at face value.

Regards, Gary Lau
MA, USA

=========================================================

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

4.5:1 is good I get it.
So I can build my secondary 2" wide and 9" tall with an input of 900
watts.
Seems we have been here before.

If 2" coil is bad and 4 is better and 6 is better and 8 is even better
then a 50" dia coil would be incredible.

So maybe I should just go with a 50" diameter coil so my height would
work out to be 225".  I could set this up and fire off some long arcs in
my back yard powering it with 900 watts.

These are both extremes.
Where is the middle ground?
Ok here is where you give examples of coils that are in the 900watt
range and tell me the diameters and heights.
NO NO NO
Don't go there please.

I am looking for WHY the middle ground is good and HOW you or they have
figured out where that middle ground.

I re word this question in every way I can think of only to be greeted
with a well meaning response that tells me this works well.  I WANT TO
KNOW WHY!!

Luke Galyan
Bluu-at-cox-dot-net

-----Original Message-----
From: Tesla list [mailto:tesla-at-pupman-dot-com]
Sent: Thursday, January 15, 2004 6:02 PM
To: tesla-at-pupman-dot-com
Subject: Re: H/D ratio

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


The optimum is 0.9.  A coil this short will have constant arcing
problems
top to primary and top to ground.  A 4.5:1 gets the toroid a distance
away
from the primary and allows an even potential buildup along the
elongated
sec coil.

Dr. Resonance

    >
    > I found on the net in a few places stating that the maximum amount
of
    > inductance from a coil is when the height is the same as the
    > diameter.  This is a 1:1 ratio.
    >
    > If that is the best inductance ratio then why is this ratio not
used
for
    > the tesla coil secondary to take advantage of a high inductance
ratio
    > between the primary and secondary?
    >
    > Luke Galyan
    > Bluu-at-cox-dot-net
    >
    >
    >
    >