Picture of Building a Tesla Coil In 9 Easy Steps!

Over the past Summer I built two Tesla Coils. The first one didn't work, so I started building this one. This instructable will outline the steps I took.

Before I begin, I feel it is necessary to go over some safety guidelines. Please read each of these points thoroughly before starting this project.

-Tesla Coils are potentially dangerous devices and precautions must be taken before every operation to help prevent possible damage to property, injury, or death. Prior knowledge of high voltage electrical safety is required, and assumed.

-The arcs from the Tesla Coil produce ozone and other gasses, which can build up to toxic levels in unventilated areas. Do not allow this to occur.

-Tesla Coils can damage or destroy hearing aids and cardiac pacemakers in the proximity of the unit. This means that Tesla Coils are capable of killing a person wearing a pacemaker. It is imperative to verify that anyone using one of these devices maintains a good distance from an operating Tesla Coil.

With that being said, here is what you're going to need for this project.

Materials :


-4' of 1.5" PVC
-8 pieces of 5"x5" plywood
-2 pieces of 3'x2' plywood
-4 caster wheels


-15kV 60ma transformer with no GFCI

Spark Gap:

-1' of 3" PVC
-2 brass bolts the same size, plus 2 nuts and 2 washers that fit the bolts
-2 1" brass balls
-1 Computer fan
-1 8 AA battery holder

Capacitor Array:

-40 Cornell-Dubillier capacitors, (Model# 942C20P15K-F)
-40 10MΩ resistors
-Material to mount your capacitors to (I mounted mine to sheets of lexan, with ceramic stand-offs as legs.)

Primary Coil:

-4 pieces of 10"x3" plywood
-50' roll of 1/4" copper tubing
-20' of 3/8" copper tubing

Secondary Coil:

-2' of 4" PVC
-1 piece of 4.5"x4.5" plywood
-~1200 ft. roll of magnet wire


-2 aluminum pie pans
-Aluminum dryer duct
-Nylon nuts and bolts


-3 copper lug terminals
-High voltage wire
-Gorilla glue
-Drill press
-Table saw

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I'm making a 10"x40" DRSSTC that will hopefully do 10-12 feet. Only problem I foresee (other than cops to scare off) is having a lousy ground connection. For full power runs this will be ran in the park across the street on a 480v battery since I live in an apartment (only room for 4 feet indoors) so can't go around pounding pipes in the ground. Hopefully a 10-foot square of 1" chicken netting will be enough.

RonA622 days ago

chicken wire ground is very interesting though will have to try and compare

RonA622 days ago

i have found that the heavier you make the ground the better the arcs like atleast 3 pieces of 1/2 copper pipe 3ft long driven into the ground and connected together with heavy wire all the way to the base of the secondary OH WHAT A DIFFERENCE!!!!

RonA622 days ago

great tutorial ive never tried making caps this way and wonder if they are as robust as the old school roof flashing and polyethylene ones immersed in mineral;oil

RonA622 days ago

i have built many of these and have always gotten the best results by hooking the cap in parallel with the tranny and placing spark gap before the tuning connection running to the primary will work in different configs though

JoshuaM2229 days ago
Hello, you by far have the best tutorial I've seen. I'm currently making a coil my self but In smaller scale, im using a transformer from an old microwave and im making a capacitor out of glass bottles, water, salt, and canola oil. I was wondering if you could perhaps break down the formula of primary cool to secondary coil length. Also for home made capacitors how much of each listed material would be appropriate.


dbiswas62 months ago
dbiswas62 months ago
And Can U PlEASE tell How to remove the GFCI from the transformer of FRANCE ,-Franceformer....plzzz ( my is 7.5kv/30ma)
dbiswas62 months ago
And Can U PlEASE tell How to remove the GFCI from the transformer of FRANCE ,-Franceformer....plzzz ( my is 7.5kv/30ma)
dbiswas62 months ago
Hey....I got every single part EXCEPT those Apple pie Cans.....I'm from India .....can someone plzzzzz help me??? With the can I can easily construct this Tesla!!!!!plzzzzzz!
KenE42 months ago
ChrisL164 months ago

Will a 3kv 30ma transformer be powerful enough?

crashstudio5 months ago

I have a different model Franceformer 15kv 60ma. After removing the GFCI I had 2 whites, 1 black/line, 1 blue and 1 orange. I had to connect white to white and black/line to orange. Blue left disconnected.

TimothyG7 months ago

About 35 years ago as a teen I saw a Radio and Electronics type magazine that showed how to make a tesla coil. At 15 I built my first with no toroid, glass plate/foil capacitors, model T ford spark coil (later moved to a neon sign transformer), etc. and had sparks about a foot or so long. I showed it to my shop teacher in school and he told me about a city industrial arts contest. I made a base from wood with dowel rods for the primary coil and stained it. I took 1st place in the R&D category at the contest. I read all I could about Tesla and even wrote a term paper. I don't know what ever happened to my tesla coil but I'm now an Electrical Engineer and I would like to build a bigger one with a torroid this time using the neon sign transformer 15kv 60mA. I would like about 2-4 feet but nothing too big as this idea already scares my wife. I have done some internet research and purchased the $5 Tesla Map software online. It says this transformer at 100% efficiency will have the potential of over 50 inch sparks. I understand your never going to get 100% efficiency but I would like to know how to design one of these spark lengths. I read that the diameter of the secondary coil affects the length. However, the software just shows the max spark length based on the neon sign transfomer specifications and nothing else. I want to make sure I can get all of the parts and do reseach before I buy anything. Comments or suggestions about this? Thanks!

Beachley (author)  TimothyG6 months ago

In my experience with the Tesla Map software I have found it to be very accurate. If I were you I would definitely follow the software recommendations. Changing the shape and the length of the secondary will not provide noticeable power gains, the transformer size is the main factor of spark length and output. If you change the secondary coil then the primary coil and capacitor bank will need to be adjusted as well. IMO it's not worth it, it would be easier and more economical to follow the specs from my instructable

leo.mecham.78 months ago

I have some doorknob caps rated for 20,000 v . will they work?

Beachley (author)  leo.mecham.76 months ago

You should really try to stick to polypropylene capacitors

tzisis7 months ago

nice tutorial man ! I plan to build my own soon and I'll sure follow your instructable. And a question. If the secondary winding is more than 1100 turns then it will output more voltage right ? So it can produce bigger sparks (with a bigger toroid and all the adjustments) ?

Beachley (author)  tzisis6 months ago

Adding additional turns will change the frequency of the secondary coil. If you add additional turns to the secondary then the primary will need to be adjusted to match the frequency. I wouldn't recommend it.

The only way to get bigger sparks would be to use a larger size transformer.

THE INSIDE (glue side) of the aluminum does not conduct electricity!!! How to build that electrical path on the top of secondary using Al tape???

Beachley (author)  hao.truong.79679 months ago

I never inferred that the glue side of the tape was conducting electricity. The wire coming off of the top end of the secondary is resting on the aluminum side of a piece of aluminum foil tape. I then placed a second piece of aluminum foil tape over top of the wire, just to secure it and hold it in place.

zorcy10 months ago

I would love to see pictures of it running.

Beachley (author)  zorcy9 months ago

I'll post a link to my youtube video

Beachley (author)  Beachley9 months ago


Sorry about that. The video had been posted before, but I guess something happened to it.

Jose EribertoP10 months ago

Hi, Tesla peeps! Can I use ignition coils of cars instead of capacitors? Can someone help me build one that is in Solid State? I'll be helping my son build his (and mine, as well) first Tesla coil for his Science Project (one that could play .mp3 music from his iShuffle). After which, we could use this on New Year's day & 4th of July. This has to be done on or before December (2014).

Mickjohno1 year ago

Mate, you're a legend! I've been on a bit of a Tesla coil quest for months now, I've built it to the stage I can test it but nothing but a spark across the spark gap is all I have been able to get. I'm brand new to instructables so already had mine mostly built when I read this but your instructions are one of the better that I have seen that's for sure. to start with despite no lack of trying I had my spark gap & capacitors around the wrong way (so I'm guessing that wasn't helping!). Also my top rail was a full circle & u said not to do that. Plus the basic wiring up of the thing was poorly described in every other vid or write up I've seen so well done.
But unfortunately I still need some help if u can please. I'm running 2 MOTs with a voltage doubler off 240volts which I think is giving me close to 8kVAC, then I've got 2 MOCs in parallel & an assortment of capacitors in series I've been trying to get right. I don't have any like yours, those suckers are expensive. I have several small capacitor banks made up & soldered together in series but I have no idea how to work out what the total capacitance would be & can't follow how to do it. I understand when I put 2 together I just add the voltage & the capacitance halves etc. But what about when I combine 2 totally different capacitor values?
My primary is 3' x 3.5" wound with 24G magnet wire & the secondary is a 1/2" tube with about 7 wraps ( I used exactly half of the reel). The spark gap improved 10 fold once I removed the capacitors & ran just from the voltage doubler & MOCs.
I'm guessing once I get the capacitors close I'll be right..?
Any ideas or assistance would be much appreciated..
Thanks heaps!
Mick :)

My main drama/question I think is how do I add up my capacitance when I have 2 separate banks with totally different capacitors in each?
Cheers! :)

WHY would you want this deleted? It was featured, and it won a contest. Looks to me like it was a great ible' before you removed all the content.

milandin1 year ago
My son and I are getting started on this Instructable and I rolled the dice and ordered a Franceformer off eBay. It's a 15KV 60mA but it arrived packed terribly and two of the ceramic terminals are bashed up badly. Two questions: Are these replaceable and if so, where can one buy these parts? I've been looking online for a while but no good so far.

I'm sure you figured this out by now that sadly, the transformer is shot and most likely is not repairable. It might be possible to mold some new separators using epoxy putty. Could be worth a shot. Couldn't you get your money back?

sheydon1 year ago

Beachley is now selling this instructable for sale on Ebay in the form of a pfd document. I am really disappointed as well as I have numerous links to this site from my own tesla web site. http://www.twotowers.com/tesla/tessie_1_tesla_coil.html - Anyone one is free to meet me there. I offer all of the information necessary to build a tesla coil. I will have to expand informationally in areas where I was relying on Beachley's instructable. This is mainly in regards to the design and construction of the base for the primary coil.

Beachley, what happened to your instructable? My son and I were using your instructions as a basis for his science project. Logged in today and *poof* it just says "Please Delete." Your instructions and images were some of the best available. Any chance of sending me a PDF? I can send you my email. Let me know.
Did you use any diode in your circuit ?
Beachley (author)  matthews martins1 year ago
Did you use any diode in your circuit ?
intead i use the same capacitor you use, can i use 146 capacitor with 2,2 uf and 250 v?
I forgot to say that they are electrolytic capacitors
or is better if i use polyester capacitors with 2,2 uf and 250v?
I am making a Tesla coil and I am only needing two parts the primary coil and plywood. But could I use adhesive to keep my toroid togethere? And what would be a good breakout point for the toroid?
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