A number of people have asked how I made the Leyden jar array used with the "Tabletop Tesla Coil." In this separate Instructable I offer a detailed explanation of how the battery was made and what it can do.
Historical footnote: Ben Franklin created the term "Leyden battery" to describe grouping a number of Leyden jars together. He made the analogy to a battery of cannons. More cannons=more boom, more Leyden jars=more zap.
Leyden jars are the oldest form of capacitor. Basically they capture and store electricity, releasing it for use by other components in he circuit. The Leyden jar was invented in 1744-45 by two men, working independently: Ewald von Kleist and Pieter van Musschenbroek. Their original version used a glass jar filled with water. Basically a capacitor consists of two conductive surfaces separated by a dielectric (an insulator). The early Leyden jar was a glass jar filled with a saline or acid solution. A metal terminal passed through the top of the jar into the water; the outside of the jar was coated with metal foil.
In 1899, Nikola Tesla used banks of liquid-filled mineral water jars as the capacitor array for his high voltage radio and power transmission experiments in Colorado Springs. Modern Tesla coil builders often use homemade capacitors in their projects, usually made from beer bottles, aluminum foil, and salt water. There are other kinds of homemade capacitors--glass plates sandwiched with layers of foil, rolled sheets of polyethylene and foil, etc. The trend among coilers seems to be away from homemade capacitors and using instead "MMCs," or Multiple-Mini-Capacitors. These are arrays of high voltage commercial capacitors arranged in series and parallel to give the desired capacitance and voltage rating. Problem is, high voltage capacitors can be expensive and hard to find. When you do find high voltage caps, they may not be suitable for Tesla coil use, as the high frequency pulsations of power through a Tesla circuit impose severe stress on the components.
Because I'm cheap and have a long standing interest in old-fashioned technology, I decided to develop a dry, non-liquid Leyden jar that would work with a Tesla coil. I wanted a capacitor made of easily obtained materials that was sturdy, effective, and cheap. What follows is the design I've come up with so far.
Step 1: The materials
To start with, you will need:
-a number of powdered drink mix canisters (Crystal Light or its generic equivalent)
-an equal number of aluminum soda cans (brand does not matter)
-aluminum ductwork tape (do not use silver fabric duct tape--it will not work!)
-plain, uncolored and unscented wax or paraffin; a pound will seal 6 of these jars
-16 gauge (or better) electrical wire; about 6 inches per jar
-large rubber bands
-a polyethylene storage box large enough to hold the array.
Everything needs to be clean, dry, and label-free. The exception are the soda cans. Soft drink logos and other graphics are usually applied as sleeves to the sides of the can. The top and bottom of the cans are bare metal. They require only a quick wipe with a solvent like acetone or xylene to get them clean and ready for electrical connection.
The drink mix canisters are made of polypropylene (PP). They measure 6.5 inches high ( about 16.5 cm) and 2.625 inches in diameter ( 65mm). They are straight side cylinders. The plastic is fairly thin and quite strong.
There are a number of brands of aluminum tape. For ductility and strength I like Henkel's Duck Brand HVAC Metal Repair tape. I prefer the two inch wide tape. You can find aluminum tape in 3 inch widths, but 2 inch gives you greater flexibility in how much surface you cover.
The 16 gauge wire is rated for 600 volts. I salvage all I need from old microwave ovens, CRT monitors, and old TVs. All the lengths you will use will be pretty short, so all those odd pieces you salvage will be useful. You can buy wire, of course. Get at least 16 gauge, at least 600 volts.
Wax is used to insulate the top of the soda can after the jar is assembled. Be sure to use plain unscented wax or paraffin. Wax is a good insulator, but dyes and scented oils may not mix well with high voltage electricity.
Rubber bands help bind the cluster of jars together. It is important the outside foil coatings of the jars make good contact with each other.
Since you will be running anywhere from 6,000 volts and up from a transformer through the Leyden jars, you'd better have a good insulated container for them. Storage boxes made of HDPE (high density polyethylene plastic) work well.