Tabletop Tesla Coil

Step 3 The primary

The primary form is a so-called 2 inch PVC pipe coupling. It actually measures 2.75 inches in diameter. The first thing to do is mark and drill holes for mounting it on the frame. Drilling in-line holes in a round object can be tricky without a jig or clamp to hold the work in place. I used the edge of an open drawer (a natural 90 degree jig) and marked two spots about 3/8ths of an inch from each end of the coupling. Use a 1/4 bit and drill carefully. Next. line up the cross piece that runs beneath the secondary coil. Using the primary coupling as a guide, center the two tubes and use the holes you already drilled to mark the cross piece. After spoiling several piece of PVC I learned it was better to drill the four holes one at a time; that is, drill the top two holes, then align your bit by looking down the inside of the tube to drill the holes through the other side.

You will need 2 1/4 nylon bolts (2 inches long in my model) and six nylon hex nuts. Insert the bolts through the holes in the primary form. Put one nut on each and tighten. Put a second nut on each bolt but don't tighten yet.

Now let's make the coil. Stick a 2 inch wide strip of double-sided carpet tape around the middle of the PVC coupling. On my model I used 12 gauge stranded wire with a heavy nylon insulation. This is sold on bulk reels in most hardware stores. At first I put on 9 turns. Later, on the advice of TeslaMap, I reduced this to 5. I would start out with 5 or 6 turns and work on tuning the coil later. The carpet tape will help hold the 12 gauge wire in place, but the insulation and thickness of the wire resists conforming, so once you have the primary wrapped, anchor the wire in place with a couple of layers of electrical tape.

Slip the primary around the secondary. Let it hang loose for a while. Push the plugs into the secondary to support it and snug up the various PVC joints. Make sure the cross piece is in place underneath the secondary and loose primary. Align the holes in the cross piece with the bolts. Attach the last pair of nylon nuts to the underside of the cross piece and tighten them just until they are flush with ends of the bolts. Now tighten the middle pair of nuts down against the cross piece. The idea is to support the primary from below at just the right height to center it around the secondary. Screw the bottom pair of nuts on each bolt up or down as needed to align the coil. If needed, you can also twist the cross piece forward or back to help center the primary. Study the photo; it should make things clearer.

Once you have the primary centered, use nylon zip ties to tie the primary wire to the cross piece. This will support the wire against pulling and help hold the coiled wire in place.

Comments

[somebody12345]

I have the exact same cardboard tube.