Step 5: Build the Capacitors

Picture of 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!
1-40 of 91Next »

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.

Morzie...!2 years ago
would you be able to use capacitors from a microwave, as im guessing you got the slow engine for the secondary from one?
If I wanted to buy capacitors instead of making salt capacitors, what kind of capacitors should I purchase?
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?
prussell33 years ago
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
wzheng14 years ago
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?
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.
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?
I used aluminum tape, simply because it was easier to work with. Not sure that is your problem though.
you tube geek group bucket capacitor. these work fantastically.
geofisiks3 years ago
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.

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.
I can generate an EM field, but I can't get sparks to come out of the top load.
My saltwater capacitors degrade after a couple of days. How do I keep this from happening?
genious1234 years ago
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..
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
wikipedia has the circuit diagram of how to connect a tesla coil
jtinio3 years ago
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??
Anything conductive works
jhunmar1004 years ago
is it ok if i used electroletic solution????
board2death4 years ago
whats nst and if possible can the maker of this diy make a remake with full revisions please
what is oil is it cooking or motor? plz reply
Kgator854 years ago
how do u plug it in, how do u power it?
You need to use a Neon SIgn Transformer. Go to this site, it tells you the best transformers to use: http://www.teslacoildesign.com/
robcwise4 years ago
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.
cbarbod4 years ago
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.
tbowers24 years ago
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.
can i use vegetable oil?
modog40004 years ago
6 nestea bottles do perfectly well they are heat treated and have a low chance of exploding
outlaws4 years ago
Do you have to use Iodized salt
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
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!
DevCoder (author)  SamuriNinjas4 years ago
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...
AHW2144 years ago
Does the metal crate electrically connect all of the aluminum foil on each bottle?
DevCoder (author)  AHW2144 years ago
luckily, yes
Wouldn't it make the most since to mix the salt and water, then evenly fill each bottle?
DevCoder (author)  bcantley20104 years ago
uhh, yeah... didn't think of that
Crtek4 years ago
what did you connect the capacitors to?
Is the wire inside touching the water?
outlaws4 years ago
How do you connect the capacitors, then hook them up to the tesla coil

ps DevCoder is my hero
Glenn7815 years ago
 for the love of god do not use 6 snapple  jars with a 15kv 30ma nst you will get about 10 min of run time out b4 1 or more blow!!! all 6 were leaking badly. i think ill try a serise/parallel with 12 of them
1-40 of 91Next »