<P> An electrolytic capacitor (e-cap) is a polarized capacitor whose anode or positive plate is made of a metal that forms an insulating oxide layer through anodization . This oxide layer acts as the dielectric of the capacitor . A solid, liquid, or gel electrolyte covers the surface of this oxide layer, serving as the (cathode) or negative plate of the capacitor . Due to their very thin dielectric oxide layer and enlarged anode surface, electrolytic capacitors have a much higher capacitance - voltage (CV) product per unit volume compared to ceramic capacitors or film capacitors, and so can have large capacitance values . There are three families of electrolytic capacitor: aluminum electrolytic capacitors, tantalum electrolytic capacitors, and niobium electrolytic capacitors . </P> <P> The large capacitance of electrolytic capacitors makes them particularly suitable for passing or bypassing low - frequency signals, and for storing large amounts of energy . They are widely used for decoupling or noise filtering in power supplies and DC link circuits for variable - frequency drives, for coupling signals between amplifier stages, and storing energy as in a flashlamp . </P>

There are two types of electrolytic capacitors which are the
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