An Overview From Ceramic to Tantalum Capacitors
- Ceramic
- Electrolytic
- Film
- Fixed
- Plastic
- Silver Mica
- Tantalum
- MV Capacitors
Ceramic capacitors are among the oldest types, some of which are obsolete. They are made by coating two sides of a small ceramic disc with silver. They usually have very low capacitance values, ranging from a few picofarads (pF) to about two microfarads (μF). Their capacitance values are usually printed on their bodies in a three-digit code. They are largely used in RF and audio circuits.
Capacitors may be fixed or variable. Dielectric capacitors are the variable type, which have a set of fixed plates (stator vanes) and movable ones (rotor vanes), with air separating the plates. Sliding the movable plates changes capacitance. The capacitors are used in tuning receivers, transmitters and transistor radios.
These capacitors are made of a paste or jelly of semi-liquid electrolyte solution and a thin oxide layer. The capacitors generally have high capacitance values and many of them are polarized, meaning that they are suitable for DC power supply and other low-frequency applications.
There are different sub-categories of electrolytic capacitors, including aluminum and tantalum capacitors. Tantalum capacitors have relatively high capacitance values per volume and frequency characteristics. However, they are more sensitive to reverse polarization, often leading to thermal runaway and explosions.
Apart from their different shapes, aluminum electrolytic capacitors usually have their negative terminals marked while the tantalum ones have their positive terminals marked.