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How to build a Tesla Coil

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Step 1: DANGER

Picture of DANGER
Unlike some other high voltage experiments, a Tesla coil's streamers can be very harmful. If you are shocked by the streamers, you will not feel pain, but your circulatory and nervous system can sustain severe damage. DO NOT TOUCH IT WHILE ON UNDER ANY CIRCUMSTANCES.

Also, I don't take any responsibility for you hurting yourself.

This isn't to say that you shouldn't get into high voltage though, its just that if you are planning for this to be your first HV project, its a little to involved. Instead, try out a nice microwave oven transformer, and be safe!

Step 2: Gather the Materials

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The total cost came to around $25, being that I already had the wood, Snapple bottles, PVC, and glue.

Secondary Coil:
  • A length of 1.5" PVC (the longer the better)
  • About 300 feet of 24 AWG copper enameled wire
  • 1.5" PVC screw-thing (see picture)
  • 1.5" metal floor flange with threads
  • Spray on enamel
  • Circular, smooth metallic object for the discharge terminal
Base and Supra-base
  • Various pieces of wood
  • Long bolts, nuts, and washers
Primary Coil:
  • About 10 feet of thin copper tubing
Capacitors:
  • 6 Glass bottles (Snapple bottles work really well)
  • Table Salt
  • Oil (I used canola. Mineral oil (horse laxative) it preferable as it doesn't mold, but I didn't have any.)
  • Lots of aluminum foil
And a HV power source such as a NST, OBIT, or other transformer that gives off at least 9 kV at around 30 mA.
stevo-d3 years ago
Ummm, harmful amounts of UV light appears to be visible at your spark gap... I'm no expert here, but from what I've read, you really should have that enclosed for the safety of your eyes... Has been described elsewhere as like watching an arc welder, and use arc welding eye protection if you DO NEED to look at it for any reason.
the current is only ~20mA, essentially the amount of power to drive an led
Your probabally going to get hurt anyway, so it doesent matter. I highly doubt that it is as bright as an arc welder, and will harm your eyes that much
Well you're right that it would not be as bad as an arc welder because if it was, it would probably melt the terminals!
My point is however that high voltage arcs do indeed produce harmful ultra violet light and just letting anyone intending to do this know to take caution.
As for "getting hurt anyway", I will disagree... Again, we should take caution... Make some pretty sparks, but DON'T make yourself part of the circuit!!!
Yeh i agree, dont be a conducter of that circuit, it will mess u up. Now that i look at the bottom, where the spark gap is, it looks kinda bright, take caution
so what would happen if i used a semi-silvered mirror to protect the spark gap, but still let u see the spark?
Semi-silvered mirror might work, but a few filters to filter out most of the light would work just as well. Rosco has UV filters you can buy, as well as good filters you could use to filter out most of the visible spectrum. That way you'd be able to see the spark but wouldn't have to worry about the intense light.
I wouldent bother...
I'm not an expert in light radiation, but I would bet you would still get UV reflecting off such a mirror.
I used to work with high intensity UV light equipment for curing acrylics and we needed to be able to watch it... We worked with the work-piece and light source behind a thick (5-8mm) piece of orange transparent perspex - you could still see the light shining, but it no longer appeared blue and no UV would get through.

I would also like to mention that the equipment I worked with was an arc lamp that sent the UV through an optic-fibre cable - the light coming from the end of the cable would easily set tissue paper on fire, and a few careless co-workers got some nasty burns.

UV LIGHT IS DANGEROUS - Be careful.
Jknapp251 year ago
It looks like your capacitors are in series, why aren't they in parallel? Also deep should the wire go into the bottle? Does it even matter because the salt water mix is considered the inner plate, the salt is all at the bottom though. Lastly, if the foil is the outer plate, how do you connect a wire to it?
current limiting capacitors, not smoothing
fang1563421 month ago

Alright, so I built it, I have everything set up, twelve capacitors, wiring is all good, but I don't get the schematic. I set up everything the way it is shown, but where do I put the secondary's wire?

pkaa2 months ago

http://how-to-build-a-tesla-generator.blogspot.co....

Hey great read here, I've been trying to find a easy to follow step by step guide on how to build my own tesla coil! I want to save money and found Ben Millers guide to constructing your own tesla generator for your home to be not that complicated! To find out more click the link above!

Nilpmet2 months ago

I would like to use commercial capacitors instead. I do not know the voltage or capacitance to get though. PLEASE HELP!

h3manth3 months ago

If I had to use ceramic capacitors in the place of the bottles, what capacitance would I need?

herrwendigo3 months ago
Where do you connect cat?
Right next to the top load...
TCoiler5 months ago
need an answer quick. is it ok to use a car battery to power a tesla coil of this size?
TCoiler TCoiler5 months ago
i would also like to know if i could not use a NST for this. i cant get one where i live.
SirCheez TCoiler4 months ago
Probably not, those transformers need mains (120V) power while car batteries are somewhere around 12V. You might be able to use a flyback or ignition coil, which doesn't need mains, but you'd need to build a driver for it and performance might be reduced.

There are a number of different transformers you can use. You could use a OBIT or a MOT (careful!) or a flyback or ignition coil, but like I said, those need dedicated drivers.
TCoiler SirCheez4 months ago
thanks. i wasnt sure, but this clarified things.
TCoiler TCoiler4 months ago
and i found a source for the NST
where did you get the tubing?
would a solid state transformer work, and if so would what efect would it have on it?
and i am not new with electricity.
A solid state transformer? You mean one that isn't directly powered by mains?

If you mean a flyback or other high frequency HV transformer, it would work, but your coil would have less power. It might have higher voltage though.
just new to tesla coils!
The Asian Cow11 months ago
Do the saltwater capacitors do well with time? I will be leaving my tesla coil at my school and it would be sitting for months at a time. If that is not good for the salt water capacitors then if I were to get an actual capacitor, what voltage and capicitance should I look for? Also do the direction, spacing, and shape of the primary coil matter? It sounds like you can "tune" it for maximum spark length but if I just set it up in a coil or helix with no measurements will it still produce something?
Saltwater capacitors could dry out... but if your salt is completely dissolved (no residue on the bottom) and the container is sealed and filled to the top, you should be fine (there's nowhere for the water to evaporate to!).
nhoven6 months ago
how many turns do you make
Knarph7 months ago
Can you tell me something about the sound pressure level of your design and even better, the SPL of the original transformer built by Tesla in the 18 nineties?
It must have bin huge!
(As if ACDC,Metallica, Deep Purple, Black Sabbath, Led Zeppelin, Grandfunk Railroad and all the other ear wasting rockbands where playing together with all their PA systems combined in a little high school auditorium....
Excuse me, my NST doesnt have a pull cord to turn it on its just something like this http://www.ebay.com/itm/Allanson-9000-V-9KV-30ma-Neon-Sign-Transformer-NST-Tesla-Coil-Jacobs-Ladder-/180857678565?pt=BI_Circuit_Breakers_Transformers&hash=item2a1bf52ae5

how do i turn it on or off?
It looks to me like you just plug it in
i have an 11.8Kv power supply made from a commercialy made tv circiut board would that work?
dan25259 months ago
Where do u connect transformer?
arpit torres9 months ago
How do you make the top part. Can you plz comment to this one.
from where have you bought thin copper tubing?
Liam.great9811 months ago
OBIT stands for Oil Burner Ignition Transformer
just wondering where would you get the neon sign transformer for cheep or free because i was looking online for them and they were pretey expansive like 75-150 dollers idk what BOIT stands for
Morzie...!1 year ago
would you be able to use capacitors from a microwave, as im guessing you got the slow engine for the secondary from one?
I wanna see him connect it to a nuclear reactor and make someone touch it. >:D
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