Resistors
De BISAWiki
A resistor is definitely an electronics factor that opposes the flow of electrons in a electrical circuit. There are several models of resistors available, plus a variety of resistance ratings, but generally each resistor will fall under one of two categories: fixed resistors and variable resistors. As the names indicate, fixed resistors have a fixed and unchangeable resistance value, while variable resistors have variable resistance values. What follows is often a brief discussion of the various common kinds of fixed and variable resistors in the electronics world.
Tantalum Capacitors Fixed Resistors
Fixed resistors are discrete electronics components that exist in many different resistance values and rated in Ohms. Common types of fixed resistors include carbon composition resistors, carbon film resistors, metal film resistors, wire wound resistors, and foil resistors. Each from the above kinds of fixed resistors has particular characteristics for that resistor type for particular purposes. For example, wire wound resistors generally can easily handle larger numbers of power than, say, carbon composition resistors, on the other hand wire coils often bring about unwanted inductive reactance in AC or RF circuits. Fixed resistors are often marked based on the conventional resistor color code.
Variable Resistors Variable resistors, because the name implies, are resistors whose resistance can be varied, whether manually or automatically. Common kinds of variable resistors include rheostats and potentiometers and are often differentiated derived from one of another by way of the linearity of their variable resistance. For example, potentiometers can be bought in linear-taper varieties and logarithmic-taper varieties that differ in the linearity of these variability as the potentiometer is turned. Potentiometers in many cases are low-Wattage devices, while rheostats tend to be used for high-power applications in industrial electronics.
The choice from a fixed and variable resistor in circuit-design depends upon whether one's circuit demands resistance values or circuit characteristics which need variability or stability. For example, if you're constructing a radio receiver that'll be fixed for a passing fancy radio frequency, then a circuit that's composed entirely of fixed-value resistors along with other components probably will suffice. If however, an example may be building a motor control circuit that calls for variation in motor speed, a variable resistor will be a more appropriate choice since a flexible resistor may be used to vary the velocity of the motor. Thus there is really a need for both fixed and variable resistors in electronics circuits, along with a familiarity with both kinds of resistors is essential you are to have comprehensive knowledge of the numerous types of circuits that can call for resistors.
