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Re: Extra coil and corona on connection wire
At 06:58 PM 09/22/1999 -0600, Tesla List wrote:
>Original Poster: David Trimmell <davidt-at-pond-dot-net>
Hi David, all,
>>As many others have pointed out to me, I should be using a large
>>diameter pipe, or flat wide strap for the transmission line to avoid
>>the corona loss. That makes sense and is definately something
>>I will try, since this was the result of some experimentation on my part
>>in the first place. Obviously, I went about this bass-ackwards, but
>>it's been a good learning experience.
>
>I wouldn't get to carried away worrying about the transmission line. The
>reason you had so much corona is because you were running much to high a
>voltage through it. I have always just used 12-16 gauge PVC insulated wire,
>for lengths up to 8 feet and 50 plus inch discharge. But when you start
>running in the multi kilowatt range, it sounds as if the Al flashing idea
>is great.
Absolutely correct..too much high voltage using a 1/4 wave
secondary as a driver. I was reading RQ's Fidonet postings on
this very issue. He suggested going to the 1/8 wave driver
to lower the voltages.
>>It was suggested that I should be using a larger diameter secondary
>>for the driver coil, possibly an 8" coil form. Any ideas how many turns
>>of wire, and how much winding area on the driver coilform I should
>>strive towards? My current specs are a 15/60, 6" secondary coil
>>and a .01 mfd cap using the RQ static gap system.
>
>If you do use a 8" form, then try to get enough wire on it for about ~5-7
>milli Henries, using 16-18 gauge PVC insulated. You don't tune for the
>secondary (driver), but for the "free resonator" (tuning for the third coil
>will get you in the ball park). Use a large top load on the resonator, also
>you can vary top C for fine "tuning".
At 7 mH using a 8" diameter coilform with AWG 18 PVC insulated wire
that ballparks about a trifle over 11" winding length of about 532 feet
of wire. That's do-able, but I will have build a another primary and
table combination, since my current one is 8" inside diameter for
my 6" working coil.
Thanks for pointing me in the right direction. It was the inductance
factor I needed to know. That and the fact I was using a 1/4 wave
secondary as a driver which had too high a voltage to drive another
1/4 wave-wound secondary as the extra coil.
>>I wasn't originally aiming at a magnifier, but since it didn't take long
>>to wind a second coil I might as well investigate this further. :)
>
>It is fun to experiment ;>) Remember that, as was pointed out by John F,
>you will not get longer sparks, but (IMHO) Free Resonators are quite
>convenient, as you don't have to worry about primary strikes, you can place
>the resonator just about anywhere you want to, etc. But some like the look
>of a "classic" coil, compact and all. It is a lot more work to build a
>three coil system, and for no major spark benefit, but it is always cool to
>do something different.
I have pigs in mind with this project and it's something I will work on over
the winter, that is lord willing when Y2K hits, that the power grid is still
up and running. Can you run a pig off a 4Kw generator? :-)
>>In some of Tesla's schematics listed in the Colo. Springs notes..he
>>shows condensers connected at some possible points along the
>>secondary. I'm curious what would happen if I connected a 50kv .01
>>mfd cap at the top of the free terminal on my working coil and
>>connected the other end to either a second coil, or a larger topload.
>>What would most likely be the outcome? I'd rather understand the
>>theory first before sacrificing a good cap. <g>
>
>If you think about it, that 50KV cap, will not last long. The voltages (and
>frequency) will make short order of it. You can try a toroid (for several
>PicoF) on the top of your driver, and/or at the base of the resonator.
I think the driver will have to have a toroid since in my experiment, with
the extra coil connected to the top bare terminal, corona was everywhere
but especially on the top windings of the the test driver coil.
http://www.fwpd-dot-net/dona/tesla/teslacoil.htm