How to build a Tesla Coil

Step 5 Build the Capacitors

I decided to go the cheaper route and build a capacitor. The simplest way is to make a salt water capacitor, using salt water, oil and aluminum foil. Wrap the bottle in foil, and fill it with water. Try to get equal amounts of water in each bottle, as it helps to keep the power output stable. The maximum amount of salt you can put in the water is .359 g/mL, but this ends up being a lot of salt, so you can tone down the amount a lot (I used 5 grams). Just make sure that you use he same amounts on salt and water. Now put a few mL of oil slowly into the bottle. Punch a hole in the top of the cap and put a length of wire in it. You now have one fully functioning capacitor, go make 5 more.

Optional: to keep the bottles in order, make or find a metal crate for them

As Glenn781 pointed out below, 6 Snapple bottles with a 15kV 30mA NST can be deadly! If you are using a NST like his, use 8-12 bottles, not 6!

Comments

[disappearingshadow]

When i wrap the glass bottle with foil do i also cover the bottom? What can i do to avoid using a aluminum tray? can I just attach a piece of wire to the aluminum foil of each of the bottles?

[prussell3]

Couldn't using salt water in the capacitor have the potential to cause a build up of explosive hydrogen gas? With high voltage sparks flying around, explosive gases would not be a good thing.

Thanks for hearing my worry

[wzheng1]

I have experimented with wine and beer bottles. but when I hook them up with my 4kv NST, the electricity leaks between the bottle and the alumnium foil outside. any body knows why?

[smoothisfast1]

Either your foil is too close to the positive lead, or your oil isn't keeping the charge from arching out of the top. Probably the former.

[wzheng1]

I made my capacitor like the one in the middle of image. I tried with wine bottles and beer bottles and snapple bottles. all experience the same phenomenon. The outside foil has a 3 inch gap to the top lead which goes to the inside.
should I use aluminum tape instead of foil?

[smoothisfast1]

I used aluminum tape, simply because it was easier to work with. Not sure that is your problem though.

[fun bags]

Make sure there all together tightly and make sure there in something all metal or you could just have to much salt.

[wzheng1]

too much salt breaks the caps too?

[makincoolstuff]

you tube geek group bucket capacitor. these work fantastically.

[geofisiks]

How do you test a salt water capacitor? I have a multimeter but it doesn't read any capacitance when i connect the two leads. This MM has micro and nano capacitance readings.

Thanks.

[smoothisfast1]

You have to charge them first with a power source. As soon as you connect your multimeter, the capacitors will quickly lose their charge, so your first reading will be the capacitance.

[smoothisfast1]

I can generate an EM field, but I can't get sparks to come out of the top load.

[smoothisfast1]

My saltwater capacitors degrade after a couple of days. How do I keep this from happening?

[genious123]

u didn't tell about the top load, making it or connecting it?? why's that?? and how to connect the capacitors, primary coils and spark gaps to the secondary coil on the PVC tube? Please elaborate these steps, some people might have a few problems understanding them.

P.S.: please provide us with a detailed schematic in which ALL the connections are shown and are PROPERLY labelled. PLEASE.... we need it..

[makincoolstuff]

the spark gap goes parallel with your power supply. The capacitors are in series with the power supply. The primary (copper tube) is in parallel with the power supply. the bottom of the secondary (the wire on pvc tube) is connected to ground and the top of the wire is connected to the topload. the top load just has to be something conductive with a smooth surface, no sharp edges (a large sphere or toroid is a common design). The secondary has no electrical connection with the primary. it is a resonance transformer.

wikipedia tesla coil

[wzheng1]

wikipedia has the circuit diagram of how to connect a tesla coil

[jtinio]

why do you used the liquid? like what effect does the fact that you used the liquids you did have on the overall effect of the telsa coil??

[fully-automatic]

Anything conductive works

[jhunmar100]

is it ok if i used electroletic solution????

[board2death]

whats nst and if possible can the maker of this diy make a remake with full revisions please

[smartbuilderperson]

what is oil is it cooking or motor? plz reply

[jj.inc]

doesn't matter, any kind works , cooking oil will rot though

[Kgator85]

how do u plug it in, how do u power it?

[robcwise]

You need to use a Neon SIgn Transformer. Go to this site, it tells you the best transformers to use: http://www.teslacoildesign.com/

[robcwise]

Would a 15kv, .0022 farade capacitor work? I have eight of them, and I constructed me secondary coil with a 3.5" x 18" pvc pipe, coiled perfectly with 22 AWG.

[cbarbod]

hey guys if I wanted to buy the capacitors instead, what would be the equivalent capacitance of each bottle? Thanks, this is for an AP Physics project.

[tbowers2]

Why didnt you just build a few leyden jars? you can use plastic tubing like a florescent bulb case and then put aluminum foil on the inside and out. The problem with glass jars is that they still hold residual moisture and cause a corona discharge. the thin plastic works perfectly and this kind of leyden jar will make a better capacitor.

[puddingsgood]

(removed by author or community request)

[mschmalz]

The tesla coil is a small functioning raw electricity genorator

[badassintheshadows]

can i use vegetable oil?

[modog4000]

6 nestea bottles do perfectly well they are heat treated and have a low chance of exploding

[outlaws]

Do you have to use Iodized salt

[kneecaps]

no. the reason you put salt is because the sodium and chlorine in the salt (sodium chloride) breaks up into free floating ions. iodine wouldnt change it

[SamuriNinjas]

Hey, I was wondering if you could just use a plastic jar instead of a glass one. Would that work? or does it HAVE to be glass?
All help would be appreciated!
Thanks!

[DevCoder]

you could use plastic, im not sure what it would do the the capacitance of the individual capacitors though. i would also be wary of fire...

[AHW214]

Does the metal crate electrically connect all of the aluminum foil on each bottle?

[DevCoder]

luckily, yes

[bcantley2010]

Wouldn't it make the most since to mix the salt and water, then evenly fill each bottle?

[DevCoder]

:|
uhh, yeah... didn't think of that
XP

[Crtek]

what did you connect the capacitors to?
Is the wire inside touching the water?