# Thread: Finalizing My Tesla Coil Build

1. I have almost finished planning my Tesla coil build, but have a few questions. It will stand around 10 feet tall including the base and 5 feet in diameter (yes, that is very big). I used TeslaMap to get most of my numbers. You don't have to answer all of my questions, but please tell me if you know!

My questions are:

-Can I make my toroid out of copper tubing instead of the aluminum spun norm?
-Can I somehow join 8 rolls of 1/8 inch copper tubing to get the desired length of 390 feet for my primary coil, or would that cause problems?
-What would be the optimal voltage rating for my MMC? Would it just be 15KV as that is the voltage of my trasformer or would it be something else? (It is currently 36KV)
-Are there any general compatibility issues with my design?

Here are my parts for reference:

Secondary Coil (capacitace=22.2pF) (inductance=377mH)

-12.75" OD PVP Pipe 5' in length
-10 lbs 24 AWG magnet wire (7770 ft) (2,328 estimated turns around PVP)
-Polyurethane Gloss

Primary Coil (required coil inductance=1,623uH)
-390' 1/8" copper tubing for primary coil (46 turns)
-13' 1/2" copper tubing for strike rail

Toroid (capacitance=45.1pF)

-7 Copper rings are used to equal the surface area of a 40" by 12" toroid. 54 feet of 3/4" copper tubing is needed to equal the surface area of 1507.2" squared.

Base

-15KV 60mA Transformer fed by 120V 60Hz outlet
-Static spark gap

MMC (capacitance=16.7nF) (Voltage=36KV)

-34 capacitors (0.15uF 2KV each) 2 strings of 18.

2.

3. Originally Posted by kubaanglin
I have almost finished planning my Tesla coil build, but have a few questions. It will stand around 10 feet tall including the base and 5 feet in diameter (yes, that is very big). I used TeslaMap to get most of my numbers. You don't have to answer all of my questions, but please tell me if you know!

My questions are:

-Can I make my toroid out of copper tubing instead of the aluminum spun norm?

Sure. It's just a "capacity hat," so as long as it's a metal, it'll do fine. The only thing to watch out for is corona discharge (or other symptoms of premature or localised breakdown) associated with sharp points. You will have to do a good mechanical engineering job to achieve the same smoothness as the spun aluminum prototype.

-Can I somehow join 8 rolls of 1/8 inch copper tubing to get the desired length of 390 feet for my primary coil, or would that cause problems?
Do it well, and it should work fine. Just make sure the joints are continuous, and that the radius of curvature remains constant.

-What would be the optimal voltage rating for my MMC? Would it just be 15KV as that is the voltage of my trasformer or would it be something else? (It is currently 36KV)
The actual value should nominally be twice the drive voltage. So, since you are driving the primary with a 15kV NST, you'd typically select about a 30kV rating for the capacitor array. Yours is rated 36kV, so you should be fine, with a little margin to spare.

-Are there any general compatibility issues with my design?
Again, the main concern is the avoidance of sharp points anywhere there is high voltage. As long as you take care to keep things smooth, you should be ok. Good luck, and let us know how it works out. Post a link to the youtube vid when you're done!

4. -34 capacitors (0.15uF 2KV each) 2 strings of 18.
hope you have plenty of money. the caps for a mates 1.8m, 500 000v tesla coil cost him \$3000. you need special caps. you can use normal electrolytics but you'll be replacing them all the time. the proper ones are very expensive. unless you have access to surplus medical gear. i hope you are aware that these caps will kill you?