Capacitor History
Capacitors: The History
In 1745, a German scientist named Ewald Geroge von Kleist developed the earliest capacitor on record, but it was Pieter van Musschenbroek, a physicist at the University of Leyden that is often credited as the inventor of the first capacitor called the Leyden Jar. Musschenbroek was a respected physicist and so his unrelated discovery just a few months after von Kleist's is often cited as the first capacitor on record.
Both men's discoveries were remarkably similar but it is Musschenbroek's Leyden jar that was well documented. The Leyden jar consisted of a glass jar half-filled with water. The jar was lined with metal foil on the inside and outside. A metal wire was threaded through the cork in the mouth of the jar. The wire (or a chain) was connected to a power source; probably a hand-cranked static generator. Once charged, the jar held two equal (but opposite) charges in equilibrium until connected with a wire that produced a shock or slight spark. It was not understood immediately that it was the glass that was the dielectric, not the water.
Early capacitors were referred to as condensers. The term was coined by Alessandro Volta in 1782, and derived from the Italian word "condensatore".
Benjamin Franklin used the Leyden jar in his early electricity experiments. He was the first to use '+' and '-' to represent the two kinds of electric force: attraction and repulsion.
Capacitors: Current Trends
Capacitors are often taken for granted even though they are one of the basic elements of almost all electronic circuits. Given the capacitor's long history, one might assume that there is little innovation and new development in the field, but today's trends in downsizing and speed have spawned many exciting developments and new technology.
Equipment from just 2 decades ago such as televisions and VCRs relied on ceramic capacitors in values up to several microfarads with aluminum-electrolytic devices spanning from 10 µF and up.
Today's technology like laptops, PDAs and smart phones require high density components that operate at high speed. Given that change, a new trend in large-capacity capacitors has developed.
The use of surface mount tantalum capacitors has increased for many reasons. While the size is a major factor, another reason for the increased use of tantalum capacitors is that tantalum capacitors require no liquid which makes them ideal for use in high temperature applications.
The downside in using tantalum vs. aluminum capacitors has traditionally been the price. With the advent of smaller surface mount capacitors, tantalum capacitors have become more affordable.
