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

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
  • 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.
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Luis9610 days ago

Can someone please clarify me on this aspect of Tesla Coils: when building one, do we have to calculate anything, like how many windings, or the capacitor's capacitance, or can we just move on without doing any math?

Thank you!

you shouldn't have to calculate the windings, but you might want to find the capacitors capacitance.

How much oil did you use and what kind of wire is that?

I'm doing this for my science fair so I would very much appreciate a quick response please.

CCube553 months ago
how many for a 3 kv nst? (snaple LEYDEN Jars) And what would happen if I did not have 6 jars...?
azvampyre4 months ago

Do we need a live cat, or can I scrape one off the road. The instructions werent clear on that point.

ChadC14 months ago

What does that cat have to do with a Tesla Coil?

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?

they prevent the coil from short circuiting... :)

current limiting capacitors, not smoothing
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.

I would care more about the radiation ;) but youre right, the UV light isnt very healthy for your eyes :P

LazerByte stevo-d7 months ago

does this just mean to wear sunglasses during use? If so, I am fine with that.

baecker03 stevo-d9 months ago
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.

adamnsmith3 years ago
i wonder if you could make a mini hand held tesla coil with a few 9 volt batterys

I would use some 18650 cells, 1x 9V-Block has about 300mAh and 9V, 2x 18650 have 9V and 3Ah (at the same size, maybe a little bit bigger), ten time more use time ;)

that would be awesome, but it would probably use up the batteries very quickly and provide tiny sparks.

LazerByte7 months ago

Should the 115VAC be connected directly to a standard US outlet with the secondary's ground actually in the ground?

sroy297 months ago
fang1563429 months 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?

Nilpmet11 months ago

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

h3manth11 months ago

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

herrwendigo11 months ago
Where do you connect cat?
Right next to the top load...
TCoiler1 year ago
need an answer quick. is it ok to use a car battery to power a tesla coil of this size?
i would also like to know if i could not use a NST for this. i cant get one where i live.
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.
thanks. i wasnt sure, but this clarified things.
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!
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?
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