There are a tremendous number of electronics components available on the market. They are frequently classified as either active or passive components. Active components are those that are capable of controlling the flow of electrons with an electrical signal. These include devices such as transistors, silicon controlled rectifiers and integrated circuits (ICs). Passive devices are electronic parts that are incapable of regulating current electrically and include resistors, capacitors and inductors. While the circuitry of an end product may consist of a variety of exotic electronics components, those listed below are some of the most commonly used with which all electronics engineers should become familiar.
One of the most important electronics components are resistors. They are passive devices that limit the flow of current to provide only the amount needed by active components such as transistors and ICs. There are several types of resistors that fall under the classification of either fixed or variable. Fixed resistors include: carbon composition, carbon film, metal film, metal oxide film, wire wound, and thin film. Variable resistors consist of a fixed resistor element and a slider that serves as a variable potential divider.
Capacitors are comprised of two metal sheets partitioned by an insulator such as a ceramic or film. They store electrical current by trapping the charged particles on the metal sheets. The metal sheets can only accept so many charged particles before it repels others. This value is measured in Farads and is the maximum charge or capacitance that the capacitor can store.
Diodes are electronics components that act as a one way conduit for current. A diode is termed forward-biased when voltage is applied in a manner where the diode allows current and reverse-biased when it is prohibited. Forward voltage is determined by the composition of material used for the p-n junction. For example, silicon diodes have a forward voltage of 0.7 while germanium has 0.3. There are several types of diodes including Zener, Diac, &Triac.
LEDs are light emitting diodes comprised of semiconductor material. When voltage is applied, the electrons and holes interact to produce energy in the form of photons. LEDs are available in a variety of colors that are dependent upon the bandgap of the semiconducting materials.
ICs consist of a number of electronic circuits on a chip made from semiconductor materials, usually silicon. They encompass a broad range of electronics components including microprocessors, oscillators, amplifiers and memory. They are classified as analog or digital depending on their application. Analog ICs are most often used for audio or radio frequency amplifiers. Digital ICs are commonly used in computers, modems and networking devices.
Inductors are passive electronic parts that consist of a conductor, typically in the form of a coiled wire. They act to resist changes in the flow of current by means of energy accumulated in its magnetic field. Inductance (L) may be determined by many factors such as the number of turns of the wire, the shape of the coil or spacing between the turns.
Transformers lower the magnitude of AC current from the main to an acceptable level for use with electronic parts with a different voltage rating. They may also be used to regulate voltage when current is transmitted over long distances. There are many types of transformers available for a wide range of applications.
Relays are switches controlled electrically. The most common types use electromagnets to accomplish switching mechanically. However, there are a number of relays that operate on other principles, for example solid state relays, which use semiconductors to perform switching.
Rectifiers are another type of diode with a relatively high current rating. These electronic parts are used to convert AC current to DC current. They also have the ability to limit the flow of DC current between its anode to cathode, and vice versa.
Crystal oscillators undergo deformation when voltage is applied. The resulting mechanical resonance of vibrations from the piezoelectric materiel crystals produces electrical signals at highly precise frequencies. They are often preferred over LC circuits and ceramic resonators due to their small size and stability.