Frost273 wrote:I tried to run my OneTesla with the secondary coil I had made at first (with 1800 turns) and I got some flashovers.
The question is can I use duct tape instead of revarnishing with polyurethane?
What are your primary coil dimensions like? If you're having flashover problems, might be a good idea to lower the primary to reduce coupling slightly, which will help a great deal and not change the frequencies too much. I recall the last time you were planning to use 8 turns? That's too much for the oneTesla design and your insulation isn't going to work or be reliable. I'd pass using any sort of tape. A simple wrap using clear plastic sheeting or transparency will work well while looking a bit nicer. For me, I think of the varnish simply as a way to keep to windings protected and together. A well designed coil should run fine without excessive secondary insulation.