Capacitors

A capacitor is a device that stores energy in an electric field, by accumulating an internal imbalance of electric charge. It is made of two conductors separated by a dielectric (insulator).

Capacitors will pass AC currents but not DC. Throughout electronic circuits this very important property is taken advantage of to pass ac or RF signals from one stage to another while blocking any DC component from the previous stage.

The capacitance of a capacitor is a ratio of the amount of charge that will be present in the capacitor when a given potential (voltage) exists between its leads. The unit of capacitance is the farad which is equal to one coulomb per volt. This is a very large capacitance for most practical purposes; typical capacitors have values on the order of microfarads or smaller.

Where C is the capacitance in farads, V is the potential in volts, and Q is the charge measured in coulombs.
The basic equation for capacitance  and the current flow through capacitor is:

Capacitor Labeling

            First two numbers forms the 2 digit value (in pF) and the third is the exponent.

K = Maximum working DC voltage

M = Tolerance

Types

Ceramic Disc, Ceramic Dipped, Resin-potted mylar/polyester, Electrolytic, Tantalum

 

Capacitors in series and parallel
Capacitors in parallel ADD together as C1 + C2 + C3 + ….. While

capacitors in series REDUCE by:
1 / (1 / C1 + 1 / C2 + 1 / C3 + …..).

Applications
Low Pass Filters (Remove high frequency noise)
Voltage Regulation
Block voltage spikes

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