You can find capacitors in almost all types of electronics today. This is the oldest electronic component with a history of about 250 years. The capacitor (or condenser) is an energy-storing device, a sort of a little rechargeable battery. It contains at least 2 electrical conductors (or plates) that are separated by a dielectric (or insulator).
Capacitors are manufactured in many styles, forms, dimensions, and from a large variety of materials. They all contain at least two electrical conductors, called plates, separated by an insulating layer (dielectric). Capacitors are widely used as parts of electrical circuits in many common electrical devices.
Practical capacitors come in a variety of shapes and sizes, and there are many different types of capacitors in use. A dielectric media separates at least two electrical conductors in most capacitors, which are usually metallic plates or surfaces. A foil, thin sheet, sintered metal bead, or electrolyte can all be used as conductors.
There are several types of plastic film capacitors. Polycarbonate, propylene, polyester, polystyrene, and Mylar are some of the more common dielectric materials used. Some of these types have capacitance values up to 100 μF. The figure shows a common basic construction used in many plastic film capacitors.
The conductor part of the capacitor could be metal or aluminum foil. A dielectric used in capacitors could be anything from glass to ceramic, plastic film, paper, and even air. It is important to know what types of capacitors are out there in order to find the one that suits your needs. Some types of capacitors include:
Adjustable capacitors that normally have slotted screw-type adjustment and are used for very fine adjustment in a circuit are called trimmers. Ceramic or mica is a common dielectric in these types of capacitors, and the capacitance usually is changed by adjusting the plate separation.