Stefan's Tesla-Pages

How to build a (better) primary coil

See my technological background page for the basic information on primary coils before reading on!

copper tubing primary coil
flat copper primary
solid wire
solid wire with insulation
how to build an optimized primary coil

copper tubing
Cheap, easy to find, easy to build, optimum performance (but you'll have to live with a big diameter of the coil!). The following image shows the primary coil of my old 4"-TC (way to much turns for this secondary...):

A slim tap connector for round copper tubing made out of fuse clips can be found on the website of Gary Lau.

flat copper
Saves space since you'll get a smaller primary coil diameter for the same inductance. Costs more than tubing, harder to find and the edges have to be sanded round to minimize corona. Best choice if you want to get a small diameter primary with lots of inductance and use it with high power! The following image shows the primary coil of Christoph Bohrs Magnifier (here is a photo of his tap):

solid wire
Have a look at my Vitamini, I used insulated wire at the inner turns and a blank solid wire for tha outer turns. Solid wire is ok for low power coils. Just avoid braided wire since it has lot of losses at RF frequencies.

solid wire with insulation

Gary Lau has a good image of his minicoil on his website where you can see how he made the tap points (1) (2).

John Freau simply taps through the insulation with a needle for low power coil.

The following image shows the SSTC of Hardy Scheidig at the GTL Teslathon. Tuning is done electronically:

how to build an optimized primary coil

more to come...