Resistors are important components of electrical circuits. Every complete electronic circuit must have a resistor of some kind. In order to prevent the damage of other components in a circuit by excess current, a resistor is used to provide resistance to the current.
Variable resistors which have a resistance that can be adjusted, as well as the fixed resistors whose value of resistance is constant, are the two common types of resistors. Because of the inability of the two types of resistors to work on the advanced circuitry present today, there was need for custom resistors to play this role. Custom resistors are produced to work on custom-made devices. They are also called precision resistors by virtue of their precision and high degree of accuracy in their operation. Certain factors determine the kind of custom resistors chosen for particular circuits. Some of these factors are outlined below.
Amount of resistance needed in the circuit. Before you select a custom resistor to use in an electronic device, you ought to know the amount of resistance which is necessary for that particular circuit. The total resistance will be the value of the custom resistor to use in the circuit. Resistance is measured in Ohms using an ohmmeter. Once this value has been established, you can then look for a custom resistor that fits it.
Another factor that determines resistor choice is the power rating of the resistor. This has to do with the amount of power in Watts that is to be dissipated by the resistor. The amount of resistance, voltage and current flowing through an electrical circuit will determine the amount of power in the circuit. Amount of power is computed as the value obtained by dividing the square of voltage by the resistance. So, once the two values of voltage and resistance are known, power rating for the resistor is calculated, and this information is used when choosing the custom resistor to fit the circuit.
You also have to factor in resistor construction when selecting a custom resistor. Construction in this regard has to do with the type of material used to make it. Custom resistors are normally produced from different kinds of materials. These include a metal film, a carbon composition, a foil, a thick and thin film, among many other materials. The material used in making a resistor will dictate how it will resist the current in the circuit.
How the resistor is mounted in the circuit. This factor also has great bearing on how a custom resistor will work. The various ways in which you can mount a custom resistor in the circuit include bracket mounting, panel mounting, PC as well as surface mounting. The kind of device into which the resistor is to be placed is what determines the kind of mounting to be used. You have to ensure that you get the proper resistor to fit the mounting technique on your circuit.