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Re: Oil filed magnifier drivers
At 11:08 PM 12/31/96 -0700, you wrote:
>Subscriber: FutureT-at-aol-dot-com Tue Dec 31 23:03:01 1996
>Date: Tue, 31 Dec 1996 15:38:39 -0500
>From: FutureT-at-aol-dot-com
>To: tesla-at-pupman-dot-com
>Subject: Re: Oil filed magnifier drivers
>
>In a message dated 96-12-30 02:09:43 EST, John Freau wrote:
>
[big, big snip]
> >>
>
>Thanks bert for the info, I can see this was a fun project!! BTW, Lou
>Balint of PA has built various oil insulated magnifier drivers, and obtained
>at least 42" sparks, he used ferrite as an additional aid for increasing the
>coupling, resulting in coupling of k = .7. I'm not sure if k = .7 was the
>final successful arrangement. His coils were cylindrical, with the primary
>outside of the oil. A unique feature of Lou's system was that his SECONDARY
>was "tuned" using an external oil emersed variable capacitor. I can obtain
>the full details of the project from Lou if anyone is interested.
>
>John Freau
>
>
Yes, John, please do! I remember Lou from the Virginia thing in '93.
I have a large variable cap I bought just for this purpose. While I have
given up on oil filled magnifiers, I have not yet tried an oil filled
vari-cap.
The magnifier I am determined to build will produce a minimum of 120 inch
sparks. I just stacked up my biggest toroids (a 42 inch x 5 and a 62 inch x
8) and put them on my resonator coil (4 inch by 13.75, 550 turns) and it
resonates at 170 khz, precisely the same as Hull's Maggie 11-e. I am
building an 11-e driver right now. The unit incorporates a very special
primary which I designed and first built in 1976; it allows me to precisely
tune the primary as the coil is running. It does _not_ use any off axis
inductance, so it does not suffer from that loss (Tesla used an off axis
regulator coil in Colorado Springs. The regulator coil may have wasted as
much as 10% of Tesla's total input power). As far as I know, no one else
has ever built a continuously variable inductance primary coil. The one
downside of a variable inductance primary is that tuning it changes coupling
somewhat. This is an important factor if using it with a classic two-coil
system, but should not be a big factor when used in a magnifier driver.
I know this primary design can be scaled up - my original was nine feet in
diameter! Building one 24 inches in diameter will be a walk in the park in
comparison. The task of constructing that big primary gave me a taste of
what Tesla went through winding his big coils.
Anyway, once I build this tuneable primary, I'll see if I can't photgraph it
and get it scanned into a JPEG. A short AVI movie file would be very good
to show it in action and demonstrate exactly how the mechanics of it
operates, but I'm not sure I know anyone who can convert a short piece of
video into an AVI file.
Some of the list members might want to try the design out on their coils.
Personally, on a two coil unit, I prefer the spiral primary design, it works
very well, and is fairly easy to build. Building this tuneable primary is
much more involved, but it does allow you to tune a coil's tank frequency
_exactly_, while the coil is actually running.
Bert Pool
nikki-at-fastlane-dot-net