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IS *EVERY* TC A MAGNIFIER?
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From: Thomas McGahee [SMTP:tom_mcgahee-at-sigmais-dot-com]
Sent: Tuesday, June 16, 1998 10:42 AM
To: Tesla List
Subject: IS *EVERY* TC A MAGNIFIER?
> ----------
> From: Steve Young [SMTP:youngs-at-konnections-dot-com]
> Sent: Monday, June 15, 1998 7:51 PM
> To: Tesla List
> Subject: Flat Primary Winding - next question
>
SNIP!
>
> This leads to another thought. If the primary effectively couples mainly
> to the lower part of a 1000 turn secondary (e.g. the first 100 or so
> turns), then do we in effect have a 100 turn secondary feeding a 900 turn
> third coil? In other words, does a conventional TC function as a merged
> combination of pulse transformer and magnifier extra coil? I envision the
> transition zone from conventional two-coil TC to magnifier extra coil would
> be a gradual effect, depending on how the primary magnetic flux was shaped
> and intercepted the secondary. I suppose the answer to this probably
> doesn't affect how to build decent coils, but perhaps it could lead to
> better understanding of how our beloved TCs actually do their thing.
> Comments?
>
more SNIPS
>
> --Steve
>
Steve,
I changed the subject title to reflect the subject at hand...
I have exchanged e-mails with Barry Benson on several factors affecting
the design of the primary/secondary system of Tesla coils, and how
they might be improved. I will re-cycle a very small portion of one
of my e-mails where I addressed the point that Steve Young has
brought up.
***** Re-cycled e-mail sent to Barry Benson 10/24/97
<unbelievably humongous snips to keep bandwidth down>
I am convinced that coilers would do well to build their higher power
TCs with a secondary *base* that is wound with heavier duty wire.
The upper part of the resonator can continue to use thinner wire.
I think we have to realize that the really high voltages we love so
much in a TC will always demand large base currents. Ultimately, I
think that even the classic TC is actually something of a magnifier
in disguise. A good TC design might entail a closer coupled
primary/base SEGMENT of what we normally think of as the secondary.
Actually, I believe the *base* of the TC secondary is the secondary
of the driver segment, and what we think of as the top of the
secondary is in reality the extra coil segment.
In the classic TC we have not spent enough thought on this. A
better model for the TC might be a primary/secondary driver segment
with really heavy duty characteristics immediately connected to
the extra coil resonator section ON THE SAME FORM. The base would
be heavy duty and enclosed by a close-coupled primary.
This base segment works via transformer action. The top of the driver
secondary would connect to the extra coil segment by first going
up several turns with very wide spacing and then quickly going
into the usual tight wound geometry.
The BASE of most classic TCs is way too small to process the
power properly.
<<In true magnifiers we usually use a solenoid style primary to
get this close coupling. Alternatives would be a flat pancake
primary and a flat pancake driver segment, or even a single
flat pancake "autotransformer" style combined primary/secondary
driver segment.>>
**** end of re-cycled e-mail
Let me try to describe the proposed TC construction:
The primary would be close coupled to the secondary segment.
Primary and close-coupled secondary would be heavy-duty.
Close-coupled primary and secondary would be driver.
Close coupled secondary would be built on wide form, preferably.
The secondary would connect to the 'extra' coil via a decent
thick wire (an extension of the secondary, which itself would be
made from thick wire). The 'extra' coil segment would be
co-axial with the primary, with the bottom of the 'extra' coil
raised several inches above the top of the secondary (the driver).
The 'extra' coil would be quite small, actually, and wound
so as to get maximum inductance.
It is interesting to note that you should be able to raise
the 'extra' coil section up as high as you want to give you
clearance for the expected arcs, without experiencing hardly
any loss other than some possible corona loss. It might be
adviseable to place a corona ring at the base of the 'extra'
coil. If a corona ring is used at the top of the driver
secondary, it would have to be split, but the 'extra' coil
corona ring can be continuous. The feed line between the
secondary and the 'extra' coil could be made from copper tubing
to keep losses down. Taken to its extreme, the top of the
driver secondary could connect to the base of the 'extra' coil
by using an inverted cone made of sheet metal. The cone
would have to be "split" to prevent induction currents. The
edges at the "split" could be slightly rolled inwards to
reduce the chance of corona at the split. This inverted cone
would give you a great low impedance transmission line that
would also match up the different diameter secondary and
'extra' coil.
Well, enough of my babbling for today.
Hope this helps.
Fr. Tom McGahee
The top segment (the 'extra' coil) would be effectively de-coupled
from the magnetic field.