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  The Layden Jar is an early device for storing electric charge that was invented in 1745 by Pieter van Musschenbroek. It was the first capacitor. It consisted of a top electrode electrically connected to metal foil coating a glass jar and a brass knob at the end. When an electrical charge is applied to the external knob, positive and negative charges accumulate from the two metal coatings respectively, but are unable to discharge because of the glass between them. The result is that the charges will hold each other in equilibrium  until a discharge path is provided.  These were first used to store electricity, but were later used as a condenser in early wireless equipment.

The Wimshurt machine is as electrostatic device for generating high voltages developed in 1880. It has two large contra-rotating discs mounted in a vertical plane. Their metal sectors rotate in the opposite direction passing the crossed metal. An imbalance in charges is induced, amplified, and collected by two pairs of metal combs. The positive feedback increases until the breakdown voltage of air is reached and a spark jumps across.