Components that are considered as “Passive” means that they do not rely on power and such component are the resistor, capacitor, and inductors. There’s more other type of passive components but the focus of this discussion is all about resistors.
Circuit designing is a complicated task where you are puzzled on defining the right value of resistors that are to be used.
Resistors are available on the market with a cheap price and there are thousand of them with different characteristics and specification.
The function of a resistor on the circuit is to provide resistance where it limits the flow of electrons depending on the specification of the component. For this reason, it can be used through different applications. Other than its ability to provide resistance, it is can also limit the flow of current, adjust voltage levels and etc…
The following are the properties of resistors: Tolerance, voltage rating, power rating, temperature rating, frequency response, and temperature coefficient.
Let’s explain the properties of a resistor one at a time starting from the tolerance. This is the value of the resistor or the range on where it can vary. The common parameters are 1%, 5% and 10%. You may find that there are other resistors that their tolerance falls below the one percent value and they are categorized as Precision type of resistors.
The voltage rating of a certain circuit can be safely adjusted or drop through the application of a resistance. Power rating is simply the amount of power consumed by the resistor. It is highly suggested to use a resistor with a power rating value over than what is exactly required.
Temperature rating is the range of the device where it can operates normally. Exceeding the limit will cause the resistor to be damaged or burnt. Finally, the frequency response is simply the change in impedance. The changes on the value of impedance depend on the function of the circuit.
Buying a resistor on the market will require you to provide them the exact amount of value as discussed on the previous paragraphs. However, before even trying to purchase them you need to make sure that they are particularly needed on your project.