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Re: Double layer primary

Original poster: "Peter Terren" <pterren@xxxxxxxxxxxx>

I used a double layer primary for the coil installed in a science museum in Australia. There were space constraints with this being a modification to a 20 year old 3 turn primary.
http://tesladownunder.iinet.net.au/Tesla%20display.htm#Upgraded%20coil.
There are three considerations.
Firstly, you can tap either side anywhere but you will have to either experiment at low power, or if using calculations, you have to add the inductance of the two coils calculated separately as an approximation.
Secondly, it may be best to use the greatest turns in the layer that is closest to the correct coupling. Eg for a 6 inch coil the primary plane needs to be about 1 1/2 inches below the end of the secondary.
Thirdly, there will be an autotransformer action between the two ends of both coils. This results in a spark that will jump greater than 1 inch between the ends of the two layers on my coil. They will need insulation between them.
Peter (Tesla Downunder)
http://tesladownunder.iinet.net.au

Original poster: Blake Hartley <teslaspud@xxxxxxxxx>
I test my coil a few hours ago and encountered a problem. the coil
worked well and performance nearly doubled, even without tuning, but
tuning is very difficult due to the proximity of the layers of the
primary. Is it OK to just leave one tap on the bottem layer on and
just adjust the top tap, or is it necessary to move them so that they
are equidistant to the ends of the tubing? Any help would be much
appreciated.

Cheers,
Blake