Re: Quick toriod question...

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

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-uswest-dot-net>" <jimlux-at-earthlink-dot-net>

if you burnish the tape, it squishes the adhesive out and gets some metal
to metal contact.  I suspect that after a bit of use, too, the small arcs
between layers will destroy the insulating effectiveness of the glue.

I note that for EMI shielding, they have two kinds of copper foil tape.
There is a smooth kind, with a conductive adhesive, and an embossed kind
(with a crosshatch pattern in it) with an insulating adhesive. The idea
being that the embossed edges poke through the glue??

Tesla list wrote:
> 
> Original poster: "Lau, Gary by way of Terry Fritz <twftesla-at-uswest-dot-net>"
<Gary.Lau-at-compaq-dot-com>
> 
> This thread raises another question in my mind.  It appears that most
> home-made toroids use aluminum foil tape as the conductive surface.  But
> even though the individual strips overlap each other, the adhesive is not
> conductive, and an Ohm meter will indicate that they do not in most cases
> connect to each other.  Perhaps the thinking is that when we're looking at
> 100's of kV, a thin layer of goo is probably not going to put up much of a
> fight before breaking down.
> 
> But even so, I've always wondered whether this resistance between each tape
> segment might have a significant effect on performance when a streamer wants
> to suck the energy in the toroid off in a hurry.  If each "plate" in the
> toroid-capacitor has a resistor and a spark gap connecting it to the disk
> terminal, that can't be good.
> 
> I've always had access to EMI gasket material at work, used to seal computer
> enclosures between sheet metal surfaces to keep RF energy inside the boxes.
> I use this EMI gasket to connect the conductive disk to every one of the
> aluminum tape strips.  An Ohm meter will show that each strip has a solid
> connection to the disk.  Pictures and words of the EMI gasket as well as my
> new 7" x 30" custom foam toroid may be seen at:
> http://people.ne.mediaone-dot-net/lau/tesla/foamtoroid.htm
> (sorry about the missing spaces on the page, still working on that...)
> 
> Back to my question - I'm wondering, am I the only person to worry about
> connections between the tape strips?  How do others deal with this?
> 
> Gary Lau
> Waltham, MA USA