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Re: [TCML] CW magnifier

Hi, Carlos,
A regular TC is the equivalent of a magnifier, in that the primary effectively only induces EMF into the bottom 1/3 or 1/4 of the secondary. The larger portion on top is fed by the turns on the bottom. Since the top 2/3 or 3/4 of the coil is not coupled to the primary, it can be physically removed and the circuit will function the same, except that the tuning will be slightly different. The coupling from the primary to the bottom part of the secondary is probably 50% to 75% or so, depending on the dimensions. The equivalent coupling in the whole TC would be in the range of 20 to 30%. In Tesla's big magnifier at CS the primary was very large in diameter and the secondary was wound on the same fenceposts, so the coupling was nearly 100%. Electrically there is no advantage to a magnifier.
The big difference with the CWTC would be that the arc to the air would not extinguish between pulses, so it would probably burn straight up with few branches and make no appreciable noise. Of course you could modulate the power supply and make it sing--might sound pretty good.
Air-core transformers have the advantage that they don't saturate or dissipate energy, but it's harder to get high coupling with good insulation in a large coil unless you pot the transformer part in oil. Yuck. 

---Carl







Hi Carlos,
      I think you are missing a key piece of information about
magnifiers, they work better than a conventional TC (arguably, not the
time guys...) based off of increased coupling.  Solid state stuff in
particular CW stuff already has a very high coupling, so the advantage
goes away.  One gets to the point where the secondary cannot take
incoming energy any faster, that is your coupling sweet spot for CW as
I understand it, and that point is reached before getting to magnifier
couplings...  You could build it, but I suspect spark length or
brightness will not be any different.  Then again there are those on
here infinitely more knowledgeable than I, so perhaps they will chime
in and teach us both something interesting.

Scott Bogard.

On 3/31/11, Steve Ward<steve.ward@xxxxxxxxx>  wrote:

Carlos,

What would be the reason for going to a magnifier?

Some of the earliest SSTCs were essentially magnifiers.  The drive was a
ferrite transformer that was used to step up a few hundred volts from a
silicon bridge and "base feed" the bottom of the resonator from the HV
output of the transformer.  This method was generally abandoned for the
typical primary coil drive as the HV ferrite transformer is non-trivial to
design properly.  Anyway, there's no reason you couldn't run a more
"typical" magnifier from a CW driver, but i also cant think of any reason
this would be beneficial over a 2-coil system.

Steve



On Thu, Mar 31, 2011 at 2:33 AM,<lightningfor@xxxxxxxxxxxxxxxxxxxxxx>wrote:


Hi
I am just wondering if anyone knows if a "magnifier" style tesla coil can
be built using CW, or does the principle only work with pulsed coils?
My understanding of them is they perform best with a low impedance driver
(primary tank/seconday coil), with a very short duration (fast quenching)
pulse...
Anyone tried CW with it...?

Carlos
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