Stephen J. Hobley wrote:
I put together a toroid tonight using some 4" ducting I had laying around, and baking pans. I taped the pieces together using the aluminum tape usually used to seal up ducting. I have a question, surely the adhesive in the tape is an insulator, so if I were to wrap the toroid in this tape it would not be continuous, but isolated areas of conduction.I've made several terminals with the ducting. Instead of starting with aluminum tape I taped the place where they were joined with masking tape [a lot cheaper] and continued wrapping that tape in a spiral around the form. After a couple of circles the masking tape pretty well fills in the space between the ridges and I then wrapped the aluminum tape [took some practice to get it smooth and decent looking]. For convenience in winding the tape was in several pieces which probably were insulated from each other by the adhesive. Final step in making the terminal was to cut two disks of thin board, cover them with aluminum foil, and then hold them together with a bolt through the middle which served to join them electrically and provide for convenient mounting later. The continuous foil of course shorted all of the turns of the tape. For smaller terminals I used sheet metal plates and I think some of the guys have used aluminum pie plates.Is this a problem? Or at high freq/voltage this kind of effect is minimal? I was thinking about wrapping the whole assembly in heavy duty foil, but again any kind of adhesive used to anchor it could create an insulation effect. I wondered what the 'correct' approach was? Steve
These things look beautiful when first made but lose some of their charm when they're dropped and dented a few times. Doesn't seem to make any difference in their effectiveness though............................
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