Any electronic or electronic circuit has resistors as significant aspects. That noted they do not play an outstanding role. As named they limit the flow of current inside a circuit. This is called resistance and is measured in ohms which represented by the Greek letter omega. A resistor limits the quantity of power that gets to the other components of the system. For example if too much power goes into an LED lamp, it will be destroyed. In this sense the resistor protects the other parts of the circuit.
Different systems require different levels of resistance. A custom resistor is therefore a resistor made for a specific system. They are designed for different systems and uses. In selecting a resistor for an individual system one should be aware of how high a temperature it can tolerate prior to getting damaged. Resistors are bound to heat up when current passes through them.
A resistor which has higher limit will become warmer than one with lower limit. The material the resistor is made of may not be capable of handling certain temperatures and therefore it will be damaged at those temperatures. A custom resistor should be put together with consideration of heat produced in use.
Tolerance refers to the accuracy of a particular resistor. It is impossible to make a resistor that is a hundred percent correct for a complex and the power flowing through it. Tolerance is gauged by plus or minus a certain percentage. For example a 5% resistor with a rating of 200ohms has a limit ranging 190ohms and 210ohms.
Materials for making custom resistors are carbon, metal or ceramic. It has to be noted that the resistors will build up heat as current flows through. The material they are made of should be able to withstand the heat without for instance catching fire or melting. Most resistors today are made of metal or carbon.
They come in either surface-mount or through-hole mount termination types. Hole mount types are normally made from metal or carbon films but they can sometimes be made from a thin metal foil. The former is usually cheaper than the latter. The Surface mount resisters are made of either thin or thick metal foil. Normally, resistors that are made from thin foil are cheaper than those made from thick foil. Equally a variable resistor is better than a static resistor. They can be regulated to work between a range of values. They are also called rheostats and are often used in such components as knobs for volume.