1. Electrolyte capacitors
i. Aluminum electrolyte capacitor:
These polarized capacitors are made of oxide film on aluminum foils. These are cheaper and easily available. The range of values typically varies from 1uF to 47000uF and large tolerance of 20%. The voltage ratings range up to 500V. They have high capacitance to volume ratio and used for smoothing in power supply circuits or coupling capacitors in audio amplifiers. These are available in both leaded and surface mount packages. The capacitance value and voltage ratings are either printed in uF or coded by a letter followed by three digits. The three digits represent the capacitance value in pF where first two digits represent the number and the third one is the multiplier digit. The letter codes are as follows:
ii. Tantalum electrolyte capacitor:
These capacitors utilize tantalum oxide which enables the fabrication of small size electrolytes. These are costlier than aluminum electrolytes and have lower maximum voltage up to 50V and are preferred where size matters. Their typical values range from 47uF to 470uF. These may be using tantalum oxide layered foils or porous anode with sulphuric acid as electrolyte in between tantalum foils in a wet tantalum electrolyte or solid tantalum electrolytes. Their SMT formats are available in standard packages where package designations have been defined by the EIA.
iii. Super capacitor:
Super capacitors also called as electrolyte double layer capacitorare made of a thin electrolyte separator flanked with activated carbon ions. These have capacitance values as high as of order of mille farads. These are used as temporary power source as a replacement of batteries.