 resistor color code description. Resistors control current flow and produce voltage drops in electrical circuits. The amount of resistance value varies anywhere from a fraction of an ohm to millions of ohms. Because there are so many possibilities and so many differently sized resistors, printing the specs on the resistor isn't practical. Instead, manufacturers print in code using colorful bands. Knowing how this code works means you'll always pick the right resistor for the job. The colored bands make up the resistor's color code. This international identifying scheme allows anyone to quickly and easily identify a resistor's ohmic value no matter its size, condition, or age. You always read the bands from left to right. Each color matches a value in the color code table. Each color represents a different number. The first three bands use these colors. The last band can contain one of these colors. Knowing there's a code is a good first start, but you also need to know how to use the code to find a resistor's value. Each color corresponds to a value in the color code table. As we mentioned earlier, the colored bands are always read from left to right. A, B, C, and D. And there's normally a gap between the C and D bands. A is the first value and B is the second. Some resistors have a third value as well, so you may see another colored bar. C is the decimal multiplier or the number of trailing zeros and D is the tolerance. For instance, say you have a resistor with four bands, green, violet, red, and gold. Using the table, you know the first digit is five and the second digit is seven. The third band is the multiplier. Referencing the multiplier chart, a red band adds two trailing zeros, which brings the value to 5,700 ohms. The gold band indicates the tolerance is plus or minus five percent, so the actual resistance is anywhere between 5,415 and 5,985. Reading the colored bands is a fast way to find the resistance of any resistor. Understanding how resistors control current flow in an electrical circuit is key for anyone working on circuit boards. Now let's check your understanding by answering the following questions. For all the electronics, the resistor is a very common component. It is important that as a technician, you can read the value of the resistor from the colored bands. Resistor color code description.