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Re: Top Load Optimizing - Q?
dear terry, for a very nice and VERY cheap toroid, take a look at
http://www.xs4all.nl/~solva/tesla.htm
Tesla List wrote:
> Original Poster: Terry Fritz <twftesla-at-uswest-dot-net>
>
> Hi Jim,
>
> At 12:28 AM 03/20/2000 -0500, you wrote:
> >Terry,
> >
> >Thanks.. you just cleared up quite a few misconceptions a newbie can make
> >(this one did anyway) concerning efficient coil design. That still leaves
> >one unanswered question however, one I was hoping Rodney's original article
> >answered. Others on this list seem to suggest a coil should run the largest
> >possible torroid a coil's design will support, and that the longest
> >streamers will result from a large-as-possible top load to delay breakout.
> >
> >So... how do I predict the (nearly) optimized torroid size for my coil given
> >my power source, tank capacitance, secondary and primary design? Is there
> >an accepted way to do this beforehand, or must I simply try larger torroids
> >until I can either no longer tune without adding tank capacitance,(run out
> >of primary turns) or until I can no longer achieve streamer breakout? <<
> >Give me a quick hint here. Thanks.
> >
> >
> snip...
>
> There is no calculation or program that will predict this. This is all
> experience but there are a few hints...
>
> If the toroid is "too small" you will get many small streamers instead of
> one long streamer. So for long streamers you want a large toroid.
> Apparently, you can get a toroid "too big" but it is pretty hard. I would
> try and get many turns on the primary so you can tune down to lower
> frequencies no mater what. My 15kV/60mA coil has 100 feet of tubing and 20
> turns on it. My small 9kV/30mA coil has 50 feet of tubing and 13 turns.
> Since the primary coil tap is the only easy way to tune a coil, I am sure
> to give myself as much room to play there as possible which means a lot of
> turns on the primary coil. Since I match the primary capacitor to the NST,
> I really can't change the capacitance for tuning so the primary coil is all
> I have to tune with. I just got a big spun toroid from Finn and I still
> only need to change the primary tape to tune it. So I would try and make a
> big toroid that does not look too overwhelmingly large for the coil. A
> smooth spun toroid gives longer arcs than the dryer duct type but the duct
> toroids are the right price... Perhaps others have some better rules of
> thumb than I on toroid sizing. I just use the toroids I have around and
> can find parts for. I really don't think about what size is best. Rather,
> I go over to the hardware store and see what the largest and longest size
> duct they have is and that determines the size of my toroid.
>
> There are people who have gotten terminals so big that they will not
> breakout. However, they just place a little nail on it and away it goes
> with great results.
>
> I am sure others will have thoughts too on the "optimal" toroid size for a
> given coil...
>
> Cheers,
>
> Terry