My Take on the Leyden Jar




Introduction: My Take on the Leyden Jar

I've seen lots of leyden jar instructables. My favorite is Kiteman's Be a Scientist: Bottle Electricity. I've made little film can jars for my little sister and she loves it.
But, be wary, I've seen one instructable that uses a photoflash capacitor or similar in the video to fake powerful "flying" sparks.

As the title says, this is how I make my leyden jars. These make nice, fat sparks. Once I finish my bonneti/sectorless wimshurst machine, I'm going to try out some 5-gallon bucket leyden jars. But, beware, these are DANGEROUS, like a loaded gun. They will KILL YOU if you arn't careful.
These smaller jars aren't deadly. But, they WILL be very unpleasant if you take a spark from them.
Anywhere, here's my take on the common leyden jar. Enjoy. =]

Step 1: Parts List

-Plastic container. HDPE plastic seems to work best, but I've found that thicker PP containers can work too. This will be the type of plastic container I'm using for the instructable.
-Aluminum HVAC repair tape. This stuff is used to mend air ducts, and also makes nice leyden jar coatings because it is already sticky on one side.
-A round-headed bolt/nail. The larger and rounder this is, the better. Don't select one too large, or the leyden jar might not charge. If you want to try a fancier top terminal, see this site, it has lots of info on leyden jars.
-Some metal bead chain or some copper wire. Whatever works for yah, though I like the bead chain more.

Hot glue gun
You hands
Some patience
The will to start over if you get it wrong
Oh, and some way to make a smooth hole in the lid of your container. This is very important.

Got all that? lets get started.

Step 2: Construction

Ok, time to get started. If you have a container like mine, you can fit you hand in it easily. You're going to have this just a little bit easier later on.

Step one: Apply a layer of foil to the outside of the jar, a 1/2" by 1" strip at a time. This will, with lots of patience and re-trying, result in a smooth, hopefully wrinkle-free layer around the outside lower part of the jar. Try larger pieces if you want, but it might end up wrinkled due to the container's curves.
Now we need to make the inside.

If you can fit you hand inside the jar, just do the same as the outside. Skip this part. V V V

For you unlucky people who can;t fit their hand inside their jars, there is a simple solution, made easier if you container is already water-tight. First, make the hole for the bolt slightly smaller so the bolt fits very snuggly in it. Then, apply hot glue around the edge so that no water can get out. After that, fill the container as much as you can with a salt water solution and screw the lid on You pretty much done here.

Step 3: Dry Jar Lid

If you applied an inside foil, then you need some way to connect that little bolt to the inner coating. I like to use bead chain for this, attaching one end to the bolt with metal tape. Then, just put the lid on and let the bead chain dangle down to the inside foil. You need one last thing for this jar.

Step 4: Finished!

Put the lid on, and you're finished with this jar.

Just hook up the bolt to your favorite generator, then charge. If you don't have a Wimshurst or Van de Graaf generator, then try this out. You don;t need the bundle of wires or anything, just hold the pipe near the bolt, or even touching it.

To discharge, fashion some "tongs" out of an old pen tube and some copper wire. You can see part of mine in the upper right corner of the last picture. First, contact the outer coating. Then, with the other end of the tongs, approach the top terminal. ZAP!

Have fun, and don't do anything stupid. Common sense is your best defense with these.



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    20 Discussions

    Update #2 HOLY COW! I just got a 2" spark off this thing after charging like forever. It was awesome.

    4 replies

    Charged with what? 2 in is like... a lot of volts lol, forgot how much...

    if i remember right its something like 1kV per cm spark through air but i'm not sure if thats right

     30kv/cm for relatively dry air at sea level air pressure, IIRC. Interesting to see people are still looking at this old instructable..

    On that day, I charged it with regular old 3/4" PVP pipe, rough paper towel, and I think an old, cleaned sock over the paper towel. It was exceptionally dry in the air that day too.

    Can you charge these with the circuit from a disposable camera? I'm guessing so, I just haven't seen anyone else ask this question.

    1 reply

    It isn't important, i'm building a small VdG, will take about 30mins or so, i'm just wondering :P

    Might work for others, the TV/CRT's I have don;t seem to hold a charge that well. Turning it on the first time works, but on/off after that gets nothing..

    okay go up there and edit your text: "They will KILL YOU if you aren't careful"...then you go to say "These smaller jars aren't deadly"... Any leyden jar is dangerous and has the potential to kill you. ALL Leyden jars should be treated as though they are fully charged.

    awesome I never knew they were built like this! a great way to charge this thing would to bring it to a mc' donnalds and put it next to a plastic slide when kids are going down. lol that might get you quite a spark.

    Thanks! My camera was performing quite well today for some reason. I took several different versions of each shot, flash/no flash, longer exposure, ect and then picked the best ones. =)

    Update! That round top terminal is more important than I realized. This refurbished jar (the one shown in instructions) outperforms the water-filled one because of the smoothness of the bolt, and can store a spark almost an inch long! The other jar can, at most, get 1/2". Big difference.

    I'll have to try graphite coated ping-pong balls like here some time...