Capacitors - A Miniture Battery
Capacitors are a common component amongst most circuits. They are like a very small rechargeable battery but have many uses for example smoothing signals, getting rid of "noise" and for keeping (volatile) meory powered when changing batteries.
A capacitor works by having two conductive plates separated by an insulator. The electrical current enters in one side and fills the gap between the conductive plates. The insulator in between the metal plates can be made of many different materials and this can make it confusing when choosing the right capacitor.
There are two different types of capacitors polarized and non-polarized. Polarized capacitors have a positive and ground leg (whereas non-polarized don't) meaning they can only be put in one way round. Polarized capacitors tend to have a larger capacitance (amount of electric charge that can be stored) than non-polarized.
Capacitance is measured in Farads (F) but 1F is a very large amount of charge therefore microFarads (μF), picoFarads (pF) or nanoFarads (nF) are used. The conversion table below shows the value of each division.
| 1F | = | 1,000,000μF |
| 1μF | = | 1000nF |
| 1nF | = | 1000pF |