Introduction: Soda Can Leyden Jar

The classic Leyden jar (an early form of electrical condenser/capacitor) is a glass or plastic jar lined with foil on the outside and inside, sometimes using salt water or acidified water as the inside electrode. In this Instructable I will describe how to make a simple, powerful Leyden Jar with common household items--no wispy foil and no heavy, messy liquids.

The video clip shows a battery of 6 soda can Leyden jars acting as tank capacitors for a small tabletop Tesla coil.

Step 1: Materials

You will need:

1. An empty hydrogen peroxide bottle, the standard 16 fluid ounce size. These are made of brown HDPE (high density polyethylene) plastic.

2. An empty 12 ounce soft drink can. Brand does not matter.

3. Aluminum duct tape. This is used to seal heating and AC ducts. Do not use the common fabric "duck" tape!

4. Round head brass screw, 8-32 size, with two brass washers and one 8-32 nut. An inch and a half long screw is fine. You can use steel hardware, but brass has better conductive properties.

5. A piece of copper wire about 3 inches long.

Optional: Brass 1/4 inch round ball, drilled and tapped for an 8-32 screw. These are usually sold in home centers and lamp shops as lamp repair pieces.


Sharp knife
Screwdriver to fit the bolt you're using

Step 2: Assembly

Wash and dry the peroxide bottle and drink can thoroughly. Soak the label off the peroxide bottle. If needed, use a solvent like Goo Gone to get the adhesive off. Both containers should be completely dry and clean of any glue or residue.

With a sharp knife (X-Acto, etc.) pierce the peroxide bottle at the bottom of the top bulge. There are two bulged areas on the common H2O2 bottle, one around the bottom and one where the cone shaped top meets the cylindrical section. Cut off the cone part as neatly as possible.

Step 3: More Assembly

Break off the soda can tab; discard. Cut a small rectangle of foil tape and cover the opening in the can as smoothly as possible. Insert the can top side down into the cut-off peroxide bottle. It should be an exact fit. If it proves to be too tight, warm the peroxide bottle with a hair dryer until it is soft enough to take the can. Push slowly and firmly. There's air inside the bottle, and you need to let it escape before the can will fit flush inside the peroxide bottle.

Cut off a piece of the two inch wide foil tape.

[People have asked, what kind of tape? What brand? I use Duck Brand Aluminum Foil Tape, made by Henkel USA.]

Apply it to the peroxide bottle just above the bottom bulge. Make sure it is even and smooth. You can polish out any wrinkles with the bowl of a plastic spoon (don't use a metal spoon, you'll tear the foil). Cut a 1/2 inch wide strip of foil tape about six inches long. Apply this across the center of the bottom of the peroxide jar. Smooth the ends evenly against the side foil. It is very important the bottom strip makes good contact with the sides. The bottom strip is your ground connection.

Step 4: Final Assembly

Bore a hole in the center of the peroxide bottle cap. Insert the 8-32 bolt with one washer against the head. Put the other washer and nut on the outside and tighten almost completely. Attach a length of copper wire to the nut long enough to make good contact with the soda can. Tighten nut. Screw on the brass ball tip, if you have one.

Fit the cone top back onto the peroxide bottle. Keep it in place with a strip of electrical tape.

A rubber band around the outside foil makes it easier to connect wires to the jar.

Step 5: Charging the Leyden Jar

This jar is quite effective. It will hold a charge large enough to hurt you if you mishandle it. Be careful.

Update: I measured the capacitance with a handheld digital meter and got consistent results of 00.32 nF (that's 320 pF) for this model Leyden jar. A variant of the Soda Can Leyden jar made with polypropylene bottles rates as high as 00.50 nF (500 pf).

Connect the outside of the jar to a ground, such as metal stove top or metal water pipe. Run a connecting wire from your charging device (a Wimshurst machine, Van de Graaff, ion generator, etc) to the center brass post. The jar will take on charge until it reaches capacity. It may arc over (spontaneously discharge) if over filled.

You can also charge these jars from TV screens, friction rods, and any other source of static electricity.

Stringing a number of these jars in parallel will create a *very* powerful capacitor bank! Be sure to discharge the jar with a U-shaped piece of wire held in an insulated handle. You will get loud, powerful sparks from this device. Leyden jars can recover charge if left sitting, so for safe storage short out the jar by clipping a wire to the center electrode and having it touch the outer foil coating.