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


I made this project, but I had to make some changes in order to make it adapt to Europe; I refer to International system of unit, and different voltage source. It's a very beautiful and functional project, thanks for havin' shared with us!

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.

RonA628 days ago

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

RonA628 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!!!!

RonA628 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

RonA628 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

JoshuaM221 month 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!
KenE43 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)  zorcy10 months ago

I'll post a link to my youtube video

Beachley (author)  Beachley10 months ago


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

Jose EribertoP11 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?
Beachley (author)  Merlinthegreat1001 year ago
You can use adhesive to keep the toroid together, it doesn't really matter what you use as long as there aren't gaps anywhere. I like to use a piece of copper wire for my breakout point. Bend one end of the wire into a circle to make a base, then point the wire straight up into the air and lay it in the middle of your toroid. I also like to take a straight piece of copper wire and tape it to the side of the toroid, pointing outwards.
Beachley (author) 2 years ago
The first point you bring up, about the size of my primary, can easily be explained. As the size of the primary decreases, the size of the secondary must increase and vice versa. I chose to make my primary longer because it is easier to do that than to wind a longer secondary.

I can't explain the spark gap, I remember reading that you should close the gap until it first starts to fire. I started at 3" and nothing happened. I shut the coil off and adjusted the gap to 2.75", nothing happened. I repeated this process until the gap fired at 2.5".

The bottom of my secondary is laying flush on top of the plywood. The plywood is acting as the plexi-glass in your example. Underneath of where I have the secondary placed, I've drilled a very small hole in the plywood. The end of magnet wire coming off of the bottom of my secondary goes through this hole and attaches to a copper lug terminal, as you describe in your comment.

So I guess the only thing I can't explain is the spark gap!

Let me know if you have any other questions.
Beachley (author)  Beachley1 year ago
I just wanted to clarify that you were correct and my spark gap was not done correctly. I have since updated this instructable to reflect the corrections that I made. Thank you for pointing this out to me.
Hi Beachley,
Thanks for the update, and you can see on my TC, that I had to increase the size of my primary to 12 winds. I'm clipped onto the 11th wind for optimal performance.

I really like the look of your new Spark Gap with the ball electrodes. I'm currently looking into building a rotary spark gap. I hear the performance increase is incredible! Alan from http://www.teslastuff.com/ sells a kit so one can put together one's own synchronous rotary spark gap. He also sells a pre-made high pass filter that he has had great success with and also the components to build one's own Terry Filter.
my coil 2.jpgmy coil.jpg
Beachley (author)  twotower1 year ago
I have heard similar things about using a rotary spark gap and I've been considering going that route in the future. In fact, it seems that most people that want to get serious with their Tesla Coils use a rotary gap. Static gaps like the one seen here are definitely in the minority. I would highly recommend purchasing parts from Alan, I've bought some items from him in the past and he is very helpful and ships fast.
Beachley (author)  Beachley1 year ago
I also wanted to say that your Tesla Coil looks great!
I would build one tesla coil just like yours, all the things are the same, but my transformer is a 15000 v with 30 mA only. It will work the same way? Because if don't work I would buy another one and put them in parallel, so I can get 15000 v and 60 mA (but it's more expensive).
Beachley (author)  matthews martins2 years ago
Since your transformer is only rated at 30 mA there will be some differences. The output you observe at the top load will be significantly less than what is seen in this instructable, your capacitor bank will also need to be slightly altered.

I would suggest you go ahead and buy another one to wire in parallel.
I would build one tesla coil just like yours, all the things are the same, but my transformer is a 15000 v with 30 mA only. It will work the same way? Because if don't work I would buy another one and put them in parallel, so I can get 15000 v and 60 mA (but it's more expensive).
divided_eye2 years ago
Hi there--I'm building a coil as my final project for one of my classes this quarter, and I really like your Instructable! I appreciate that you put in the effort to come up with a solid, clean design, and your instructions are overall pretty clear. I'd like to use this Instructable as one of my primary guides while building my TC... but I have a 12kV 60mA transformer (the only 15kV 60mA ones I could find online are going for upwards of $280--no luck looking locally, either), and most of the D.I.Y.s online use a 15kV one (like yours). What adjustments to your design would I need to make in order to follow this Instructable with a 12kV transformer instead? (I'm also using the DeepFriedNeon website as a reference, and I've read through dozens of other TC-building guides already). Thanks for your time!

I'm hoping to see some big TCs at the Maker Faire this weekend :D
By the way, what I mean by "adjustments to your design" is adjustments to the design of the base/structure for the TC; I know that I'll need fewer capacitors and whatnot [I'll do those calculations on the DFN site ;)]. I'm just trying to figure out what materials I'll need//how much it's gonna cost me to put it together. Also--do I really need to buy a whole 50 feet of 1/4" copper tubing? I'm working on a fairly tight budget... The transformer I got was $125, and I'm hoping to keep it under $250 for the whole project. Thanks again (in advance)!
Beachley (author)  divided_eye2 years ago
With your transformer, I would build the secondary and primary exactly the same as I have. I used a 50' roll of tubing to play it safe, using 50' provided me with many turns to ensure I would be able to achieve the proper resonance. Since your power supply is smaller you will likely need to tap the primary at a location other than the one I have. You can use whatever length you want, but make sure you have enough turns to tune your resonance properly. For capacitors, I recommend going with two strings of 16 capacitors, making a total of 32 capacitors. This is assuming you use the same capacitors as the ones I've used.
Great! Thanks for the timely response!
twotower2 years ago
Hi Beachley, A couple of questions if you have time....

What mathematical formula did you use to calculate your capacitor value? As you know, I followed your design and used 40 of the Cornell Dublier caps in a series/parallel configuration. However, this does not seem to jibe with the formula others are using to calculate the correct capacitance for a tesla coil. In my case the equation looks like this:
C = 1/(2π*60Hz*15000V/0.060A) = 0.00000001061033 = .0106uF

If I am not mistaken, the capacitance of our MMC is 0.3 (0.15 + 0.15) MFD 40,000V (20 X 2000).

The other question I have is regarding my Safety Gap. I know that you do not use one. However, I fried my first NST only minutes after I ran the tesla coil for the first time, due to a voltage spike that kicked back from the primary and secondary coils and fried my NST. The problem I'm facing at the moment, is that no matter how I try to adjust the safety gap and spark gap, that the safety gap fires way too much. The coil may run fine for 10 seconds or so, but then all of a sudden the Safety Gap begins to arc repeatedly and I need to shut the coil down.

Any ideas? I'm about ready to build a rotary spark gap. Have you built one yet?

Peace, Steffan
Beachley (author)  twotower2 years ago
When calculating the capacitance, I used a very basic rule. One of the first things I learned in electronics class was how to add resistors and capacitors in series and parallel.

For resistors in series,
Add the value of each resistor. The acquired sum is your total resistance.

for example,

Let's say we have five 2 ohm resistors in series.

Total resistance = 2+2+2+2+2=10 ohms

For resistors in parallel,
Add the reciprocals of each resistor. Divide that number into 1.

1/2 + 1/2 + 1/2 + 1/2 + 1/2 = 2.5
Total resistance = 1/2.5= .4 ohms

The method for capacitors is the exact opposite.

For capacitors in series,
Add the reciprocals of each capacitor. Divide that number into 1.

for example,

In this instructable we have twenty .15 MFD capacitors in series.

1/.15 + 1/.15 + 1/.15 + 1/.15.......and so on..........= 133.33
Total capacitance = 1/133.33 = .0075 MFD

For capacitors in parallel,
Add the value of each capacitor. The acquired sum is your total capacitance.

In this instructable we have one string of capacitors with a total capacitance of .0075 MFD and then we have another string of capacitors with a total capacitance of .0075 MFD.

So... when we combine these two strings in parallel,

Total Capacitance = .0075 + .0075 = .015 MFD
The Geek group was using the same formula. I was always under the impression that the capacitance value of capacitors connected in series does not change; only the voltage rating?? Apparently I have been mistaken all this time. Adding the reciprocal of the value for each capacitor and then dividing that into 1 provides the accurate capacitance of the MMC. Thanks! I think I get it now.
cjones712 years ago
how much did this cost.
in total.
Beachley (author) 2 years ago
Your site looks good, thank you for referencing me. I really like your vacuum method to keep the spark gap cool, I'll have to give it a try one of these days.

I'm glad your Tesla Coil turned out so well!
twotower2 years ago
I just want to share a Tesla coil update. First let me say that I am getting up to 3.5 foot sparks off of my top-load. I opted not to mount a battery operated computer fan underneath the lower table which had a hole cut out and sucked air through the 4" PVC Pipe Spark Gap above it. I opted to mount a 120V computer fan from above and blow down onto the spark gap. I drilled a series of half inch holes at the bottom of the PVC pipe spark gap housing in order to vent the exhaust. That did not work at all. Then I watched a video where a guy built a suction spark gap out of a PVC conduit fitting. When the vacuum was engaged, the spark output off of the top load was nearly doubled. Very clever! It gave me the idea to merely flip my fan motor around and see if pulling or sucking air through the spark gap housing would make a difference. I also taped up all but two of the 1/2" holes at the bottom of the PVC housing in order to create a true negative pressure inside the spark gap housing. The two holes left (one on either side), are perpendicular to the spark gap electrodes. I thought this would provide the best quenching effect. SUCCESS! My spark output nearly doubled and I can also now run my coil for up to 30 seconds at a time. The 120V Computer fan I purchased from Radio Shack (Catalog No. 273-242) is much more powerful than a 9V battery operated fan and may be considerably more effective for quenching and cooling. I recommend giving my method a try.

If you like I can upload images of my modified version of your gap. I was completely surprised by how well is quenched.

I also run my coil through a variac now. Once you have a variac, ... you never go back!
sheydon2 years ago
My Tesla Coil Is now working again. I put another 15KV 60mA NST into service after my first transformer got fried from kickback from the tesla coil. I now included a safety gap across the capacitor and a variac. Its easy to do and I recommend doing it to save your expensive NST. A variac alone will not prevent your NST from getting destroyed from T. Coil kickback. Below are two youtube links to videos of my coil in action. Enjoy

sheydon2 years ago
Hi. Just an update. I finished my coil yesterday but was having difficulty getting any noticeable activity on the top load. To make a long story shorter, I would up extending my primary coil from 7 to 11 winds. That was all I had space for. I clipped onto the 11th wind and I was getting beautiful sparks up to 12" or so. On about the 4th test, Kickback from the tesla coil fried my transformer. I will be installing a variac in front of the new transformer in order to reduce the possibility of this happening again. Good news is that I do have a nice working coil. I will upload photos with sparks as soon as I round up a new transformer.

I used an alternate series-parallel configuration for the same forty Cornell Dublier .15MFD caps in order to save space and to be able to fit the MMC neatly under the primary and secondary coils. I'm uploading images of this cap layout. If anyone is interested I can upload a link to a pdf file. A large format printer would be ideal to print this larger that 8.5'X11". I got the idea from thegeelgroup.org. It works great.
Series Parallel 1.jpgSeries Parallel 2.jpg
sheydon2 years ago
Hi Beachley,

Did you ever wind up using a safety gap, reactor or variac to limit the possible kickback into the transformer? My 'tesla coil expert friend' is recommending that I include a reactor (basically a large resistor) on the "hot" line voltage lead before the Transformer. I don't recall you using anything like that in your design. I was just wondering if you have experienced any issues with your transformer just using the basic tesla coil schematic that only utilizes a transformer, spark gap, capacitor, primary coil. secondary coil and a top load? I'm adding a photo of my Tesla coil so far. I just need to build the MMC array. Caps should be arriving tomorrow!
Beachley (author)  sheydon2 years ago
The Tesla Coil looks really good! The best way to protect your transformer is by utilizing a Terry Filter, you can find a page on Terry Filters here:


When I built mine I chose to stick with what you call "the basic tesla coil schematic." The main thing that needs to be avoided in order to prevent damage to your transformer is to make sure the arcs generated at the toroid NEVER strike the primary. I have never had this happen because I used a strike rail, and from your picture it looks like you used one as well. The strike rail has been sufficient enough for me and I've been running my coil off and on for the past 9 months or so.

As far as the variac is concerned, that's up to you. It gets hooked up just as you described in your comment and it basically acts as a large potentiometer. It's kind of cool to be in control of the input/output of the coil, but I wouldn't call it necessary. I might add one to mine in the future but, at the time, I was low on cash.
nerd74732 years ago
Well done Beachley, this is an awesome Tesla coil i want one do you think I should make one or buy one?
nerd74732 years ago
This is the coolest ever I want a Tesla coil
whon10152 years ago
My Tesla Coil
Thank you so much for putting this instructable out here on the internet. It helped me very much in creating my tesla coil. This is my first one and it works beautifully, it has so far been able to produce up to 4 foot sparks. I still have a bit of tuning to do, but it is amazing. Again, thank you for putting in the time and effort to create this instructable.
Beachley (author)  whon10152 years ago
That's awesome!

Thanks for sharing it with me, I'm really glad to see it run so well. I put a lot of effort into this instructable and it's nice to see that it's helping people.
sheydon2 years ago
I seem to be unable to upload images form my Mac. Too Bad.
agis682 years ago
nice project. I guess the most difficult thing was the coils.maybe i missed on text but how many turns is the secondary coil?
Beachley (author)  agis682 years ago
Thanks for the compliment.

To answer your question, I briefly mention the secondary has ~1150 turns in "Step 6"
louis.m2 years ago
Very nice with all these pictures, but what I miss is an electric diagram.
Beachley (author)  louis.m2 years ago
I've just added a circuit diagram to the "Wiring" step for you.

Thank you !
What a nice diagram, and quite simple.
Only one more suggestion, could you integrate the resistors also ?
Beachley (author)  louis.m2 years ago
I hope you find it helpful!
You have a lead coming from your capacitor bank and connecting to the primary winding and a lead coming from the spark gap and connecting to the primary winding. Is this correct? Whenever I try this configuration, my spark gap fails to fire. When I remove the lead from the capacitor bank to the primary winding, my spark gap fires, but I fail to get sparks from my toroid.
Beachley (author)  smoothisfast12 years ago
What you've said is correct. Have you attempted to tune the primary? Take the wire that runs from your capacitor bank to the outer turn of the primary and try placing it on different turns until you find a sweet spot. If the primary is not properly tuned it's possible for your spark gap to not fire.

You say that when you remove the wire connecting the capacitors to the primary, your spark gap fires. This means that your spark gap is spaced well enough, so you shouldn't need to do anything there. The previously mentioned wire, however, cannot be removed if you wish to achieve arcs from the toroid. The wire in question is very important, it completes the primary circuit and is the most important wire of the project, in the sense that it must be moved around until optimal results are achieved. By moving this wire, you are effectively altering your primary's resonance.
i was looking at your diagram as well as another diagram i found in a book and noticed that the location of your spark gap and capacitor were switched, does this affect the performance of the coil?
Beachley (author)  faschr40232 years ago
The diagram you are describing is another common method of wiring a Tesla Coil.

Both configurations will produce the same result.

The method you read about in your book and the method I've described here are the only 2 ways it can be done. As long as you follow one of these methods you will be ok.
I thought so, but to be sure to be sure, thanks.
Beachley (author)  Beachley2 years ago
If you are looking for anymore information beyond what I have given, I suggest taking a look at "deepfriedneon.com"

It's a very comprehensive and informative site.
rc jedi2 years ago
SAFETY NOTE: after turning off, the spark gap discharges the cap only down to the breakdown voltage of air. Not completely discharged to 0 volts. I got shocked. They tell me I attended the third grade, but i now have no memory of it. but really, a capacitor should be treated as if it is charged once it has been in use. Your tesla coil is a thing of beauty.
Beachley (author)  rc jedi2 years ago
Thanks for the kind words. Given the right conditions, getting shocked by the capacitors after shutdown could be fatal, this is exactly why I chose to wire a 6MΩ resistor in parallel with each one.
dima1232 years ago
I have a 6Kv 60 milliamp transformer, so the capacitance is about 0.027 uF. Is it better to attach six of the mentioned capacitors in series (voltage=1200, capacitance = 0.0249 uF), or five of the capacitors in series (capacitance = 0.03 uF, voltage=1000)
Beachley (author)  dima1232 years ago
I would do two strings of 11 capacitors in series, then wire the two strings together in parallel.

This will give you a capacitance of .027 uF and a voltage rating of 22000.
how expensive are the 942c capacitors?
Beachley (author)  clevelandstorms2 years ago
One capacitor is roughly $7
lis.tesla2 years ago
can you please correct me if i'm wrong?
but this is how I understood you wired the capacitor bank

(p.s. I just doodled it up and scanned it in)
would you be able to show me a diagram of the cap bank
thank you
Beachley (author)  lis.tesla2 years ago
You're drawing is correct.

todd 3.jpeg
is the polarity important on the capacitors
Beachley (author)  lis.tesla2 years ago
Nope, the polarity doesn't make a difference.
your is better though. thanks!
J-Five2 years ago
surpcrepair2 years ago
questions: i see people making these all the time and they look cool. But what is the practical use for this thing or is there any? Or is it just a weird looking machine that makes lightening looking stuff from electricity and looks cool?
Beachley (author)  surpcrepair2 years ago
When Nikola Tesla built his, it was in an effort to provide the world with "Free wireless electricity." He spent a fortune constructing Wardenclyffe Tower, a huge Tesla Coil in New York. His plan was to channel the electrical discharge emitted, to the earth. Through this approach, he believed he could electrify the Earth. With the Earth electrified, people around the world would be able to channel electricity by simply pounding some sort of metal rod into their yard. Wardenclyffe Tower was never fully operational, and was demolished in 1917. Many modern scientists are skeptical that this idea would've worked.

After Wardenclyffe, Tesla Coil circuits were used commercially in sparkgap radio transmitters for wireless telegraphy until the 1920's.

Today they're mostly for entertainment or educational displays.

Tesla Coils can transmit electricity through the airwaves to an extent. If you view the video I embedded in this instructable you can see what I mean. Notice in the video that, lying on the top layer of my base, are four fluorescent light bulbs. You'll notice that when I supply power to the coil, the lights faintly illuminate.

Tesla Coils also can also be used to cause interference in radio and other electrical signals. They also produce ozone, which can be used to purify water.
I've always been amazed that even with all of today's technology WE STILL CAN'T BUILD A TESLA COIL AS GOOD AS THE ONES TESLA BUILT. Think about when he was alive and what he had available to him for materials and science. No computers, no really advanced math theory in the area, etc.
The man was freaking brilliant and had many other inventions to his credit as well, some of which are today finally being brought into usage! I think you've seen the pictures of the kid touching the metal ball with his hair standing up, apparently unharmed that is a tesla coil, the energy flows over and around the body but not through it, it's why millions of volts can be moving through that coil but you are not harmed because there is virtually no amperage to drive it through your body. If you've never seen the the movie "The Prestige" pick it up, it's a sci fi rendition of some of Tesla's theories that were funded into reality by a magician looking for a perfect trick that no one else could duplicate. While we might look at his work these days as entertainment, at some point the lightbulb will go on and someone will see what he saw and finish his work, I truly believe that.
If you believe that the "philadelphia experiment" really happened, Tesla was supposedly involved in that as well. If you've never heard of it, it was supposedly an effort at some sort of "cloaking device" to use star trek terms. A navy ship was outfitted with coils and some other gear and supposedly phased out of sight but supposedly never came back. If you believe the conspiracy theorists it actually did come back with crew members embedded into metal decks etc. If there were any survivors of the ordeal no one will admit it...it's put in the same class as the ufo crash in roswell new mexico. Tesla is a fascinating subject if you're inclined to study up on him.
I thought that the philadelphia experiment was to prevent magnetic underwater mines from tripping by the ships hulls magnetical effect.
They tried to achive this with a coil around the hull, running alternating current through it.
Beachley (author)  t.rohner2 years ago
I'm interested in where you heard this theory.
Well, it's the only plausible cause to me, why the navy would do such things.

I'm not into conspiracy theories, except they make sense.
When i first heard about it, it must have made the most sense to me.
But never underestimate the sick brains of warmongers...

Maybe all of it is bullshit.
Here is a excerpt from wiki, but this doesn't make it true or false.

Misunderstanding of Documented Naval Experiments

While personnel at the Fourth Naval District have suggested that the questions surrounding the alleged event arise from routine research which was performed during the Second World War at the Philadelphia Naval Shipyard, it was previously believed "that the foundation for the apocryphal stories arose from degaussing experiments which have the effect of making a ship undetectable or 'invisible' to magnetic mines."[9] Another possible genesis of the stories about levitation, teleportation and effects on human crew might be attributed to experiments with the generating plant of the destroyer USS Timmerman, whereby a higher-frequency generator produced corona discharges, though none of the crew reported suffering effects from the experiment.
Did "They" check the duty roster?
Beachley (author)  rfitzgerald12 years ago
I completely agree, Tesla was one of the most influential people in history. Everything that he accomplished was ahead of his time, who knows where we'd be if Edison had ended up standardizing a DC power grid.

I've never seen "The Prestige", but I'm going to check it out.
sheepishly, :) I spent weeks investigating the claim from Tesla websites that a tesla generator could power my house! Beware of the huge scam! Fortunately, I'm too parsimonious to part with money without turning over the dollar at least a hundred times! I wonder how many parted with their cash though!
Wouldn't a working Tesla generator be a great thing? I can always dream!
Beachley (author)  Ole bally2 years ago
Maybe some day!
Tesla coils have only a passing resemblance to sparkgap transmitters. They are totally different animals. See http://en.wikipedia.org/wiki/Spark-gap_transmitter and http://en.wikipedia.org/wiki/Arc_converter.
Rebreg2 years ago
your giving me bad ideas >:D
BytePilot2 years ago
Beautifully written, simple to follow and informative.
Excellent work sir, excellent work...
Out of curiosity did you ever figure out why your first one never worked?
geo bruce2 years ago
how did you bend the primary's copper tubing?
Beachley (author)  geo bruce2 years ago
New copper tubing comes pre-bent into this shape.

All I had to do was spread the roll of copper tubing apart, letting it drop into the 4 wooden braces I made in "Step 5."
oh nice
what's the average cost for the copper tubing?
Beachley (author)  geo bruce2 years ago
You can probably find a 50' roll of 1/4" copper tubing for around ~$40-$50.
ok thnx
Beachley (author) 2 years ago
The wire mesh is serving as my ground in this project.

This type of ground is called a counterpoise ground. If you're interested, you can probably find a lot of information about it online.
Beachley (author)  Beachley2 years ago
I explain this briefly in the wiring step.
DevCoder2 years ago
Wow, excellent coil! This is pretty much what I wanted my first one to look like if I had more money and time ;D
Beachley (author)  DevCoder2 years ago
Thanks! I've read some of your instructables in the past, you have some pretty cool projects
PsychoDad2 years ago
Really really cool! But I think you should add a warning that persons with a cardiac pacemaker shouldn't try this at home...
Beachley (author)  PsychoDad2 years ago
You're right, I just updated it to reflect that. Thanks!
schumi232 years ago
Out of curiousity, how m uch was the total cost for this?
Beachley (author)  schumi232 years ago
Between the transformer and the capacitors, I probably spent ~$500 or so. Most of everything else I had lying around the house.

To cut the costs, you could try to find a transformer for free from a local shop as suggested below. I attempted to do this but every transformer I came across had a GFCI circuit in it.

The capacitors are up to you, they definitely played a big part in the cost. There are instructables on here for making the Leyden Jar type, but keep in mind these capacitors can be hit-or-miss. Another challenge with Leyden Jar capacitors is getting consistent capacitance values.

Aside from those 2 things, the rest of it is relatively low cost.
Hoopajoo2 years ago
Oil furnaces have a sizable transformer. One from an older oil furnace should work great for this project. Just ask a HVAC shop if they have an old one from a system replacement or find an old, replaced oil furnace curbside.
They're dead handy to get to, open the panel and four long bolts to get the transformer...

I've one kicking about - 15KV think it's 30ma...
Kiteman2 years ago
That's a cool project, well done.

<sub>(You can embed the video here, you know.)