Resistors are an integral part of any electrical or electronic circuit. They do not do anything that would stand out within the circuit though. Resistors as the name suggests resist the flow of current within 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. An example would be when a bulb receives too much light the bulb will eventually be damaged. In this sense the resistor protects the other parts of the circuit.
Varying systems require varying levels of resistance. A custom resistor is one made for a particular complex. They are designed for different systems and uses. Before purchasing a resistor, it is necessary for you understand the amount of heat the resistor can endure before wearing out. Resistors become warmer when current passes through them.
A resistor which has higher limit will become warmer than one with lower limit. The substance a resistor is made of may not be able to withstand some levels of heat and will be damaged. A custom resistor should be put together with consideration of heat produced in use.
Tolerance refers to how correct a resistor is. 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. A good example would be a 5 % resistor that has a value of 200 ohms will exhibit a resistance of between 210 ohms and 190 ohms.
The main materials used to make custom resistors are carbon, ceramics and metals. 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. Modern day resistors are made of metal or carbon.
Resistors are made either surface-mount or through-hole mount termination designs. Through-hole mount are either made of carbon or metal film or very thin metal foil. The former is much cheaper. Surface mount resistors, on the other hand, are normally made from thin or thick metal foil. Thick foil resistors are cheaper than thin foil resistors. Variable resistors are also way better than static ones. The resistors can also be regulated to operate within a range of values. These are called rheostats and are common in components such volume knobs.