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Re: [TCML] Acrylic sheet for primary coil insulator

An Acrylic sheet does not stop any rogue streamers outright, but I feel it deters. I have a sheet over my primary which is 4mm thick. This cover is circular, and is around 6" wider on its radius than that of the outer turn of the primary. It's on the edge of the #underside# of this cover, about an inch in from the edges, where I have stuck an earth wire running around the circumference, (less a 1.5 inch gap of course).

It can be glimpsed here as the wire surrounding the copper primary which is the blue disc on the left side (stuck on with bathroom sealer - I never said it was pretty!).


This is stuck to the Acrylic and has its own separate earth that hangs down and clips onto the main earth connection to the coil. The thinking behind it was that a top surface mounted earth wire around the edge is bound to attract, the same goes for a conventional raised strike rail but probably more so, but this one being on the underside, and slightly inwards, it would have less of an 'attraction factor'. NB: 'Less' is NOT that same as 'No' attraction!

Streamers that were heading for the top of the primary now have a tendency to curve around the edge and under the protective sheet to the earth wire. Seen here: https://www.flickr.com/photos/33962508@N03/8186445442/in/dateposted/ However in this case what was probably going to be a ground strike has been diverted - but it demonstrates the principle.

Streamers can easily strike through 4mm thickness though if they wish, leaving tiny pin sized holes with a black sooty ring to them.

Also some experimenting showed a cover of 4mm makes next to no difference to the coupling (I actually measured it once, both with and without a cover, using a method from the archives involving putting mains voltage into the primary - NO I can't remember how, but it was dangerous)


On 02/09/18 16:50, Steve White wrote:
I am considering adding an acrylic sheet as a top cover for my primary coil to minimize primary strikes. I never would have considered such a thing because of the expense but I recently acquired a large sheet of 5/16" acrylic sheet for nothing, so that idea has now returned. My question concerns the strike rail. Should I install one with this cover or not? Here are my options as I see them:

1. No strike rail
2. Strike rail in the normal position on top of the acrylic sheet
3. Strike rail under the acrylic sheet

My concern with number 1 and 3 is that if a streamer finds its way around and under the acrylic sheet, the streamer may melt or burn a portion of the acrylic. I have heard of at least one coiler that has installed such an acrylic sheet and I recall that he placed the strike rail under the sheet. I forgot the link.

Steve White
Cedar Rapids, Iowa
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Regards Phil www.hvtesla.com
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