There are fixed, variable, and physical quality resistors. They are made of carbon composition, carbon film, metal film, thick and thin film, foil, or wire wound to resist electricity.Resistors can be used in many ways besides resisting electric current. Large resistors enable the stored kinetic energy to be released; hence they are used as electric power brakes in trains. They are essential in generating heat, matching, and loading circuits, dividing voltage, fixing time constraints, and controlling gain. They are used to power LEDs and blower motors. Here are details about resistors that you should know.
Use color-coding to identify resistors quickly. The resistance and tolerance values of a resistor are displayed by several colored bands. Most resistors have four colored bands. The color bands are integrated on the resistor’s body. The first two bands show the primary digits of the resistance value. The third band represents the multiplying factor (which determines the resistance value). The last band shows the tolerance value.
You cannot sue the color-coding method to identify all resistors because an SMD resistor is too small to have colored bands on it. Instead of the colored bands; SMDs have a numeric based code. The rapid-fire pick-and-place machines that manufacturers use allow them to standardize SMD resistors because they are all small in size.
When choosing a resistor, there are three simple steps to follow. First, calculate the resistance that you need using Ohm’s Law using a standard formula. Know your voltage and current for you to calculate its resistance level. Your second step will be to calculate the power rating of the resistor. The power rating of the resistor is the level of power it will be dissipating. In the formula where P (power in Watts), V (voltage drop across the resistor), and R (resistance of the resistor in Ohms) the power rating is calculated in the example below. Your LED has a 4V voltage, the resistor has a 200 Ohm value, and the power supply is 10V. Find the voltage drop of the resistor. 10V – 4V = 6V. 6V is the voltage drop and this answer is applied further as P = 6V*6V / 200 Ohm = 0.18 Watts. Buy a resistor that will fulfill your objectives after you get the resistance and power rating values because these values should guide you to get the most suitable one.