Sunday, September 20, 2009

Tesla Coil Primary Construction

Below is an excerpt from my Tesla Coil Plans available with over 90 pictures (including a
lot more of the primary construction). Available for $12 at my website,

Place the four 7 inch standoffs at even points on the top pine circle of the base to support the Lexan circle. Find the center of the Lexan circle and use the same procedure we used on the bottom pine circle of the base to mark two lines that bisect the Lexan at 90 degree angles. Use these lines to align the standoffs along the outer edge of the Lexan . Once aligned, mark the points and drill a ¼ inch hole on each one to attach the standoffs. Also drill a ¼ inch hole in the exact center of the circle.
Before we wind the primary, we have to make the support combs(see pictures previous page). You have many different options here. If you Google “Tesla Primary Coil Supports” and hit the images tab, you will see many different versions of ways to support your primary. For our example, I am going to make the combs out of Polypropylene (soft plastic cutting board material). The photos are very detailed and should answer most of your questions on the construction of the combs. Basically, you drill fourteen, ¼ quarter inch holes in a straight line evenly spaced at ¼ inch to 3/8 of an inch apart. The dimensions in our example combs when finished are 1 inch x 9 ½ inches. To allow the copper tubing to be placed in the comb, the top 15% of the ¼ inch holes are cut off using a table, saber or band saw. Try and leave as much of the hole as possible, while still allowing room for the tubing to be pressed in. Some things to keep in mind as you wind the primary. First, don’t unroll the copper tubing. Try and use its original shape to your advantage. You want to keep the amount you bend the tubing to a minimum. The copper tubing tends to become “work hardened” and tough to work with if you bend it to much.
Winding the primary With our four inch secondary, we want the center hole of the primary to be about 5 ½ inches in diameter. Drill a ¼ inch hole in the Lexan about 1 inch from the side of the secondary. This is where the copper tubing will go through the Lexan base so you can make the electrical connection underneath the primary coil. Press the tubing into the combs working your way around until you complete the secondary. I find, adding just a small drop of hot glue works well to hold things in place. Don’t over do it with the glue or you will have a mess on your hands. Take your time. This is a slow process. At the outside edge of the primary coil, when you finish the last turn, you will trim the excess with a tubing cutter and glue the final end in place. Plan on spending about 1 hour after you are done “tweaking” the copper tubing positioning to get a great professional finished look.
Thanks Alan