Re: Capping secondary coil forms

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <FutureT-at-aol-dot-com>

In a message dated 12/17/02 3:28:58 PM Eastern Standard Time, 
tesla-at-pupman-dot-com writes:


>Hello all,
>
>All these years I have been capping my secondary forms with
>plexiglas/acyrlic or lexan/polycarbonate discs. This apparently
>prevents arcs down the centre of the secondary. I have never
>questioned this theory until now. I just made a new secondary and
>really couldn't be bothered capping it, though I eventually did
>anyway. But I really think that if the toroid is large enough, arcing
>inside the form wouldn't happen anyway. I've noticed that arcs never
>seem to leave the centre of the toroid, supporting my theory. Is this
>just another theory that stems from the days of doorknob discharge
>terminals? Anyone out there running uncapped coils with outputs that
>vastly exceed the winding length?


Greg,

It's been my view that capping is not usually needed.  I usually run
my coils uncapped for sparks up to 2.75 times the secondary length.
I've never had any sparks go into the secondary.

In one case with my tube coil, the spark was 3.5 times the
secondary length, and there was no problem with an uncapped
secondary.

Others have reported they had problems though, so I don't know
what the true answer is.  I don't know what may happen at higher
powers, etc.

It would be good to get to the bottom of this mystery.

John


>Cheers,
>
>Greg.
>