Types of Capacitors

Types of Capacitors

The below is the Types of Capacitors

Electrolytic Capacitors

Aluminum electrolytic capacitors are made by layering the electrolytic paper between the anode and cathode foils, and then coiling the result. The process of preparing an electrode facing the etched anode foil surface is extremely difficult. Therefore, the opposing electrode is created by filling the structure with an electrolyte. Due to this process, the electrolyte essentially functions as the cathode.

Electrolytic capacitors are soaked in a liquid or paper impregnated with a liquid which is not a dielectric but when a voltage is applied creates a layer of aluminium oxide which acts a the dielectric. The reaction is dependent on the polarity of the applied voltage. If the polarity is reversed the capacitor will produce a gas and is likely to explode or burst because of the pressure inside and so are not suitable for alternating current applications. 

MEMs Capacitors

Micro Electro-Mechanical System(MEMs) are small devices manufactured from Silicon. Plate capacitors can be fabricated which show small changes in capacitance a the separation of the plates is increased or decreased. The small devices can be used as sensors and gyroscopes. 

Common types of devices are the parallel plate capacitors for position sensing. Also, interpenetrating comb-like structures, in which the capacitance may be altered using by moving one comb relative to another, either in the transverse direction or longitudinal direction. Because of their small size, the variation in capacitance is very small, of the order 10^-15 F. (femto-Farads).

Tantalum Capacitors

Tantalum capacitors are polarised and have low voltage ratings like electrolytic capacitors. They are expensive but very small so they are used where a large capacitance is needed in a small size such as mobile phones or laptop computers. These capacitors have increasingly become an important as the demand for ever smaller electronic gadgets has grown. Columbite-tantalite - coltan, for short, the ore from which tantalum is refined is mined in Australia, Egpyt. The high demand for the ore has also financed civil wars in the Democratic Republic of the Congo. A UN security council report charged that a great deal of the ore is mined illegally and smuggled over the country's eastern borders by militants from neighboring Uganda, Burundi and Rwanda providing the revenue to finance the military occupation of the Congo. 

Super capacitors

Super capacitors are capacitors which have the ability to store large amounts of charge, and therefore energy, in a very small volume. Energy storage is by means of static charge rather than of an electro-chemical process that is inherent to the battery. Applying a voltage differential on the positive and negative plates charges the super capacitor. This concept is similar to an electrical charge that builds up when walking on a carpet. The super capacitor was first conceived in 1957 but now research is focused on using these as a light weight power sources as an alternative for batteries. the super capacitor crosses into battery technology by using special electrodes and some electrolyte. Super capacitors could find applications such as temporary back-up power supplies in the electrical power grid or providing the initial burst of energy to get electric cars moving.