[Prev][Next][Index][Thread]
Re: Primary spacing on large coil. (fwd)
---------- Forwarded message ----------
Date: Tue, 30 Apr 96 13:24:00 PDT
From: Richard Hull <RICHARDH-at-whitlock-dot-com>
To: bin <bin-at-poodle.pupman-dot-com>
Subject: Re: Primary spacing on large coil.
Robert, and others.
We at the TCBOR have fiddled with really high voltage in TC's. The
temptations and benefits are very tempting. A very small capacitor can be
used for very large powers and the output voltage from the TC will be much
higher due to the increased energy. The real rub comes from the fact that
above 20,000 volts, corona and insulation of primary tank connections
becomes a real bear. At around 30,000 volts, only the most heroic efforts
will succeed in properly containing the primary energy.
Tesla had the capability of 60KV in Colorado and this is often spoken of by
people in the TC building field. Tesla never used voltages above about 30kv
more than once! (this blew his caps up!) He quickly reduced his normal run
voltage to about 25 KV. He used the term "a number of jars gave way" to
delicately describe the catastrophic explosions in the tanks. I wouldn't
want to go finishing around in salt water to retrieve shattered shards of
glass bottles!! This was down time to Tesla and he never ran this
experiment again. He also complained of "flaming at the rotary" when even
25,000 volts was used. Admittedly, his gap system in Colorado was terrible,
but with high voltages, extra efforts must be poured into gap design.
My advice would mime yours Robert, let someone else pioneer this sticky
area for now. We are just trying to do our best under 20,000 volts. A lot
of extra bucks will need to be spent in the region above 20KV just to
insulate and avoid corona flashover and bleed.
Richard Hull, TCBOR
----------
From: bin
To: Tesla-list-subscribers
Subject: Re: Primary spacing on large coil.
Date: Monday, April 29, 1996 9:25PM
>From rwstephens-at-ptbo.igs-dot-netMon Apr 29 21:09:29 1996
Date: Mon, 29 Apr 1996 13:07:38 -0500
From: "Robert W. Stephens" <rwstephens-at-ptbo.igs-dot-net>
To: tesla-at-pupman-dot-com
Subject: Re: Primary spacing on large coil.
>>From larrycg-at-intele-dot-netSun Apr 28 22:06:15 1996
>Date: Sun, 28 Apr 1996 10:17:51 -0600
>From: "Larry C. Gardner" <larrycg-at-intele-dot-net>
>To: tesla-at-pupman-dot-com
>Subject: Primary spacing on large coil.
Larry Gardner wrote,
>I am currently in the process of building a large Tesla coil.
>It will have an input of 50KV at 100mA. The primary capacitance is
>12.5nF, and will resonate at 120kHz. The secondary has a diameter of 15
>inches.
> The problem here is how far apart do the primary winding need to
>be in a large coil? In the smaller coils built I know that primary
>sapcing was recommended to be from 3/8 to 1/2 of and inch.
> Any help would be greatly appreciated.
>Larry Gardner
>"The present is theirs, the future, for which I really worked, is
>mine"-Nikola Tesla
Larry,
Break timing jitter and dwell start to deviate wildly and
become increasingly hard to control with conventional rotary breaks at
such voltages. The only reason I can figure that you must wish to
try this is to get higher power from a very high voltage, small value
capacitor that you must have lucked upon and that you also have a
100mA, 50 kilovolt transformer. I think the extra problems that you
will have with your break merely to achieve 5 kilowatts, commonly
achieved by simpler means, will diminish the value of this exercize.
However,... if you want to go to that trouble to charge a LARGE value
capacitor at 50 kilovolts with say 1 amp or more, I'd say go for it before
I
do so and maybe I can learn from your mistakes!
Happy coiling!, rwstephens