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The Simple Tesla Coil

The Simple Tesla Coil

This is a guide on how to build a medium sized Tesla coil. I built this one from parts I had laying around, all I had to buy was magnet wire, in all I spent less than $30! For those building their first coil, I would not suggest using this a standalone source of instructions. This is my first coil, and I used a multitude of sources to make it. Also, I did the boring math part behind it. At first I tried to skip some of the math, and just "wig it" but that didn't work. For the math part I would suggest deepfriedneon.com, but I found a much simpler site : http://www.classictesla.com/java/calculat.html#WireFreq . Once you know what materials and dimensions you will use, go to this site to get the whole resonance thing synced up as closely as possible. Read this entire guide, and maybe the comments section, before doing anything. Also read some other guides and maybe the Wikipedia article on Tesla Coils before deciding whether or not to embark on a shockingly frustrating, but rewarding journey. I built this for a high school science project, and although I finished at the last minute, it didn't take more than maybe 20-30 hours of work. I entered a few contests with this so you should vote for me if you enjoy this instructable.

I also must say that by using any information in this guide you assume all risks involved with the components, operation, and construction of Tesla Coils or any part of the circuitry described. I do not take any responsibility for injury or damage resulting from the use of this information. Tesla Coils CAN KILL YOU! Whether it be the streamers, 15kV NST output, or the simple (and most dangerous) 120V wall outlet input. All the currents involved with this project are dangerous! I would recommend working with someone experienced with high voltage if you are not. Also, this device is a major FIRE hazard. Use it only outdoors. To sum it all up, this project is risky, be careful.
 
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Step 1My Understanding of the Inner Workings of a Spark Gap Tesla Coil

My Understanding of the Inner Workings of a Spark Gap Tesla Coil
From what makes sense to me, the Tesla coil is a magnetic resonator, otherwise just a really powerful transformer. Wall outlet current is converted to 15000 V by the NST, which then charges capacitors, which (once fully charged) allow electricity to temporarily "jump" the spark gap, which allows current to temporarily flow through the primary coil, generating a magnetic field, which the secondary picks up, and converts it back to a current (of higher voltage), which then flows into the ground and into the air (What a sentence!). This process happens 120 times per second or something like that. The Tesla Coil not only steps up voltage but also frequency, which makes the pretty streamers of death that obviously fascinate you (that's why you are here). Due to this high frequency, your nerves would not feel pain from the streamers conducting into your body, but they still cause damage! Basically, your insides would cook and you wouldn't feel a thing, but that is not going to happen because you are not to touch the streamers! Don't do it! Oh yeah, the diagram is from Wikipedia, thanks to another instructable to pointing out to me which one to use. Use the bottom diagram. The top one didn't even work when I tried it, and the bottom one makes more sense.

For the High Voltage transformer, I used a 15kV NST.
For the spark gap, I used two bolts in opposite sides of PVC pipe at a set distance.
For the HV capacitor, I used salt water "Leyden jar" capacitors made of Snapple bottles.
For the Primary, I used .25" diameter copper tube.
For the secondary, I used 24AWG magnet wire wrapped around 1.5" PVC.
For the Torus, I used Aluminum Dryer Duct that I cut open and wrapped around two aluminum pie pans.
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26 comments
Nov 5, 2011. 10:53 PMspark light says:
Nice instruct able. Well written and illustrated. :D
I just have two tips for you:

1) People aren't as smart as one might assume. I've seen this happen on my own Tesla Coil instruct able.

2) Try a shorter, fatter secondary. I have seen this common misconception happier to even some of the more experienced coilers. You will get a much better output for all the work you are doing. ( Congrats on getting what you did! )

A good ratio for secondaries is about 3.5-6 times the diameter is an appropriate height. So say you had 3 inch O.D. PVC, an optimal length would be around 12 inches. Stick by this and you will see a great increase in performance. A side note:
As tesla coils use resonant rise, turn count DOES NOT MATTER. Thus, height has no advantage.
An exception: on the smaller end of diameters, you want to a ratio of 5 MAX.
Apr 13, 2012. 5:46 PMdisappearingshadow says:
if i get a 15kv 30ma transformer, how would the dimentions of the tesla coil change?
Mar 4, 2012. 7:19 PMlis.tesla says:
how did you ground your Tesla coil
Jan 2, 2012. 2:19 AMShadow613o says:
...I'm making a tesla coil for my school science fair, and don't want the coil to be realy dangerous, so could I use about 2-3k v. ???????
Jan 4, 2012. 4:31 AMShadow613o says:
OK.
Dec 29, 2011. 10:11 PMBumba Lodh says:
ok i will!!!
Dec 28, 2011. 10:14 PMBumba Lodh says:
Hi,I built a TESLA COIL with 5kv 30ma nst.Primary coil made with 4mm
copper tube with 10 turns secondary made with 2inch PVC pipe.Winding
height 10.2inch(0.315mm enameled copper wire used) also made Capacitor
bank with 2kv 0.15uF polyester film capacitor.But the problem is my
Capacitor burnt several times but the coil works with LEYDEN JAR
capacitor.Why the capacitor burning??????


Please Help Me!!!!!!!!!!!!!!!
Nov 26, 2011. 2:04 PMturner_chris1 says:
I like the bit where he says - it didnt catch fire until the 3rd or 4th time!

be careful be very very careful!
Nov 8, 2011. 10:31 AMnixnix says:
WELL SHURE YOU CAN BE MURDERED BY THIS KIND OF CONTRAPTION , BUT THIS IS NOT TESLA COIL - IT IS SIMPLE HIGH VOLTAGE TRANSFORMER. TESLA COIL PRODUCES AC VOLTAGE WITH MUCH HIGHER FREQUENCIES( MHZ OR MORE ) WHICH FLOWS ONLY ON THE SURFACE ( YOUR SKIN ) SO THEY CANNOT HARM YOU . THIS IS CALLED "SKIN EFFECT ". 60 HERTZ WILL FLOW THROUGH YOUR BODY AND CAN HARM YOU BADLY . THIS INSTRUCTABLE IS WRONG AND DANGEROUS !!!!!!!
Nov 15, 2011. 6:10 PMTeslaling says:
That is where you are wrong. This happens to be a tesla coil, not unlike the coils Mr. Nikola Tesla himself built. A tesla coil is simply an air core resonance transformer. This means that the frequency of the primary is such that it is tuned to the secondary's natural resonance, which in turn resonates, creating a stepped up voltage beyond what are possible with a convetional air core transformer (one who relies on electromagnetic fields). Now as to frequency, technically, you could make a tesla coil resonating at any frequency. Most coils resonate in the hundreds of kilohertz. Some of the larger coils can be as low as 50 kHz. If you were able to make a coil and top load big enough to resonate at 60 Hz, then you would only have to wrap a couple of coils of wire around it and plug them into the wall socket.

It is a very common misconception that tesla coils need to run at high frequencies to be considered tesla coils, when in fact they actually need to resonate.

You also mentioned the skin effect. As MistaStokes said, the skin effect apply very well to human flesh. Instead its the incapabilities of your nervous system
Nov 15, 2011. 7:39 PMTeslaling says:
After saying that, I had to try to see how big it would be and it ends up being like 200 feet tall and 12 feet wide, with 2 toroids being like 400 feet across each!!!
It would also use like 10 tons of copper wire!!!
Probably safe to say that its impossible.

I really want to build another coil too. My first one was a little 12" tall coil that throws 6 inch arcs at best and my second was a VTTC that throws 7-8" streamers. I want to see 2 foot arcs!

I'm having the same problem. I can't find any transformers on craigslist and they are way too much on ebay, well the high power ones are. I might start to call around a at neon supply and repair shops.
Nov 19, 2011. 11:21 AMTeslaling says:
How big of a coil are you talking?!? Pole pigs are usually used for coils that like 10 feet tall!

Pole pigs are very heavy, upwards of 200-300lbs, very hard to come by and very expensive. My guess it that it would be easier to buy one than to make one because it will require a lot of iron (specially shaped) and even more copper wire. I know people have had very good success powering large coils, 4 feet tall or bigger, with nst and microwave oven transformers (MOT). It takes a fair amount of math and understanding to make one that big with good results, but i think its worth it.

I recommend using a 15kv NST at 30 or 60 mA or 2 MOTs in series with a voltage doubler to get 8kv at a few hundred mA.
Nov 15, 2011. 4:34 PMmrmerino says:
UV filter? I know UV is bad for you eyes, I wonder if you could block the UV coming out of the tube. Or maybe just seal it off
Nov 7, 2011. 11:32 AMcronama says:
im kinda new to this and already i want to make a tesla coil that you can use to play music like a boss. thanks for the foundation project.
Nov 7, 2011. 5:27 PMJackn7 says:
As with all high power/current devices, precautions and safety should be 1st on ones mind, however, when dealing with Microwave Oven transformers, be VERY careful!

It only takes once to kill or maim...
Nov 7, 2011. 3:55 PMstephenfitton says:
Great work,just a couple of safety points Circa1990 we experienced with a 4800 watt coil,this is well above all safety levels,built by an expert team,any digital device with in its range running either reprograms,or cancels same.Any neon bulb will light up if held in the hand up to a quarter of a mile.The unit was dismantled afterwards to prevent any further problems. A good fun starting point is yours, wishing you all the best and safe handling.

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Author:MistaStokes