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Difference Between Electrolytic & Ceramic Capacitors

by Renee Miller

Capacitors are electronic devices made up of two plates composed of electrically conductive material. The plates are separated by an insulator which may be liquid, gaseous or solid. Capacitors store electric energy in a process called charging. Charging enables capacitors to remove direct current signals as well as electrical noise from DC power supplies for computers, audio gear and other devices. Two commonly used types of capacitors are electrolytic and ceramic.

Design

Electrolytic capacitors consist of two small sheets of metal, shaped into cylinders, and separated by an oxide layer. This type of capacitor is polarized: one plate is always positive and the other sheet is negative. It’s very important that they are connected the right way. Changing the direction of the polarity in an electrolytic capacitor could cause it to explode. Ceramic capacitors have no polarity. They are made by layering conductor sheets which alternate with ceramic material. Typically ceramic capacitors are disc shaped, but they may be made in other shapes.

Materials

Ceramic capacitors are made of materials such as titanium acid barium as well as ceramic. The conductor material in ceramic capacitors is usually metallic. Electrolytic capacitors use two layers of aluminum foil plates that have a paper material between the plates. The aluminum foil on the plates, used in electrolytic capacitors, is treated to make it work efficiently and correctly. It is anodized to form a layer of aluminum oxide on one or both sides which acts as the insulator (blocks flow of direct current). To increase the capacity, the foil might also be etched by a chemical process before anodizing.

Size and Shape

Most ceramic capacitors are disc-shaped devices about the size of a coin or smaller. Electrolytic capacitors are typically cylindrical, ranging roughly from the size of a soda can down to that of a vitamin pill.

Capacity

Electrolytic capacitors have a large capacity, which means they can accumulate a large amount of energy. Ceramic capacitors are typically small and have small energy storage capacities.

Applications

Electrolytic capacitors are typically used in power supply applications for voltage filtering, but are also used frequently in audio frequency amplifiers. Ceramic capacitors are often used for radio frequency and in some audio applications. Generally the ceramic capacitors are small and are not constructed with an internal coil; this is why they are preferred in the high frequency applications. They are usually used in circuits which circumvent high frequency signals to ground.

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