Introduction to Capacitors

Electronics 1 CVHS

Terms 

Capacitance

- the ability to store energy in the form of an electric charge 

Capacitor

- a device designed to hold capacitance

Details    Base Unit -

Farad

   Typically measured in micro-farads Symbol:  F (1/1,000,000th of a Farad) Also can be in pico-Farads (1/1,000,000,000,000) of a Farad Also have a working voltage rating   WVDC Similar to resistor power rating Capacitors are not heat sensitive

How a Capacitor Works  A capacitor is two conductors (plates) separated by an insulator (dielectric)  A capacitor stores energy when it is connected to a voltage source (such as a battery).

 Current flows until the capacitor becomes charged to the same voltage as the source.

Simple Capacitor

Discharging a Capacitor      Capacitor has the ability to discharge immediately Battery discharges over time Short leads of capacitors before working with them Use a resistor to slowly discharge a capacitor so it is not damaged Danger of Electrical Shock

Factors Affecting Capacitance  Plate area  Distance between plates  Dielectric material

Schematic Symbols  Non-electrolytic capacitor  Electrolytic capacitor    has polarity dielectric soaked in electrolyte Never install backwards  Variable capacitor  plate surface area can be adjusted

Types of Capacitors  Non-electrolytic  Ceramic Disc  Dipped Mica  Paper (molded)

Types of Capacitors  Electrolytic  Radial Lead  Axial Lead

Types of Capacitors  Variable

Capacitance Code

NOTE: Value is in pico-farads!

Practice

First Digit Second Digit Third Digit Letter 1 0 4 K 100,000 pF or .1 µF ± 10% 5 2 8 4 2 F 5,800 pF or .0058 µF ± 1% 3 G 24,000 pF or .024 µF ± 2%

Review  Capacitance vs. Capacitor  Unit of Measure & Ratings  How Does it Work?

 Working Considerations  What affects Capacitance  Three Types of Capacitors  Capacitance Code