|We begin by looking in detail at the resistor, used in PLC'S, Drives, Temperature Controllers, Computers - Televisions - Radio - Walkman - Playstation - Automobiles etc etc. In fact virtually every electronic device in the world today uses this component, without the resistor all current control, biasing networks and feedback in amplifiers would be impossible to achieve. |
It is interesting to note that the current flow through a resistor is proportional to the voltage across it, this will be shown later R = V/I. Any conductive material has its resistive content dependent upon its length. the longer a piece of wire - the higher its resistance, the shorter its length and/or the greater its diameter - the lower the resistance value will be. However not all resistors are made from wire.
There are several types of resistor, these differences effect the components Stability, Tolerance and Power rating. The figures below are general and depend upon the manufacturer.
Carbon resistors are the most generally used resistor type in the world today. They are cheap, have a good range of values available and their power ratings are ideal for Radios and Televisions.
< film on surface of the rod
The rod is then machined so that the conductive material resembles a resistive length of wire.
Therefore a marking of Red-Green-Orange would be 25000 or 25Kohms.