Resistor Color Code

Color-coded resistors are resistors that are coated with a certain color code to represent their resistance when packaged. Color-coded resistors are often seen in household appliances, electronic instruments, and electronic equipment. Color-coded resistors are the most common in electronic circuits. Commonly used electronic components. This article details color-coded resistor reading methods for 4-strip, 5-strip, and 6-strip resistors. The number of resistor strips varies from 3 to 6, and together they specify resistance value, tolerance, and sometimes reliability or failure rate.

Why is the resistance value not directly marked on the resistor?

Commonly used resistive elements are generally very small. If the resistance value is directly printed on it with numbers, it will be difficult to recognize. It is not easy to print such small characters on a cylinder. And when the resistor is installed, it is rotated at will. If the printed number is just clamped down on the circuit board or blocked by other components, it will not be recognized. And use the color code (color ring) instead of the number to mark the resistance value of the resistor. To overcome these defects, on the one hand, the color is easier to recognize than the thin numbers, and on the other hand, it can ensure that the color code (color ring) can be easily and clearly seen no matter what direction the resistor is installed.

How to read color coded resistors?

The color band has 12 colors to represent, and each color represents a certain number, as shown in Figure 1. To understand the color band resistance, you must know the corresponding relationship in the resistor color code chart. We can also use the Resistor Color Code Calculator to quickly find resistor values.

Figure 1: Resistor Color Code Chart

4 band resistor

4 color codes are usually used for resistors of a general nature. Its encoding method is as follows:

1. The first color represents the first digit of the resistor

2. The second color represents the second digit of the resistor

3. The third color represents the multiple of the resistance

4. The fourth color represents the accuracy of the resistor

Figure 2: Four band resistor

This resistor has 4 color bands, the first 3 are close to the distance between the 4th and 3rd (as shown in Figure 2), and the first 3 next to each other are used to indicate the resistance value, the 4th The distance between the first band and the third band is longer to indicate the manufacturing error level of the resistor. It is the last band of the 4 color band resistors. The first color band in the 4 color band resistors represents the basic tens, The second color band represents the basic unit, the third color band represents the magnification (the power of 10), in short, it is followed by several zeros after the two numbers, and the fourth color band represents the Manufacturing error, the first three colors of this color band resistor are green, blue and red. As can be seen from Figure 1, green represents the number 5, blue represents the number 6, and red represents the number 2. Therefore, the resistance value of this color band resistor It is 56x10²=5600. The color of the fourth color band is golden, which means that the error of the resistor is 5%. Therefore, the resistance value is between 5320 and 5880 Ω (5560 ± 5%)

5 band resistor

5 color codes are usually used for high precision resistors. Its encoding method is as follows:

1. The first color represents the first digit of the resistor

2. The second color represents the second digit of the resistor

3. The 3rd color represents the third digit of the resistor

4. The 4th color represents the multiple of the resistance

5. The fifth color represents the accuracy of the resistor

Figure 3: Five band resistor

The 5-band resistance has one digit band more than the 4-band resistance. Among the first 3 bands, the first color ring represents the basic hundreds, the second color ring represents the basic tens, and the third color ring represents the basic ones. , while the 4th track is the magnification and the 5th track is the manufacturing error. For this 5-band resistor(as shown in Figure 3), the first 4 colors are brown, yellow, purple and black. According to the resistor color code chart, brown represents the number 1, yellow represents the number 4, purple represents the number 7, and black represents the number 0 (10 ⁰ = 1). The resistance value it represents is 147x10⁰=147, and its fifth track is also golden, which means that the manufacturing error of the resistor is also 5%.

6 band resistor

The 6 color codes are typically used for high precision, high value resistors. Its encoding method is as follows:

1. The first color represents the first digit of the resistor

2. The second color represents the second digit of the resistor

3. The 3rd color represents the third digit of the resistor

4. The 4th color represents the multiple of the resistance

5. The fifth color represents the accuracy of the resistor

6. The 6th color represents the temperature coefficient (ppm/K)

Figure 3: Six band resistor

The sixth color represents the temperature coefficient of resistance, which describes how much the resistance value changes with temperature. The range of this color is brown, red, orange, yellow, blue, purple, gray and white, combined with the resistor color code chart, they respectively represent the temperature coefficient of 100ppm/K, 50ppm/K, 15ppm/K, 25ppm/K, 10ppm/ K, 5ppm/K, 1ppm/K and unlimited.

The temperature coefficient expresses the percentage that the resistance value will increase when the resistance value increases by 1 degree Celsius. For example, if a resistor has a temperature coefficient of 100ppm/K, its resistance value increases by 0.01% for every degree Celsius increase in its resistance value.

The 6-band resistor example shown in Figure 5, combined with the resistor color code chart, orange = 3, brown = 1, brown = x10, green = 1%, red = 50 ppm/°C. Represents a 3.21 kΩ resistor with a 1 % tolerance and a 50 ppm/°C temperature coefficient.

Resistor color code history

The color coding of resistors dates back to the early 20th century, when the electronics industry was rapidly developing and needed a standardized way to mark the resistance value of resistive devices. The original resistance marking method used different lengths of wire or foil to represent different resistance values, but this method was not intuitive enough and confusing.

Later, the International Electrotechnical Commission (IEC) formulated a set of international standard ribbon resistance coding IEC 60062.

The IEC 60062 standard specifies the use of 6 colored bands to represent the resistance value and precision of a resistor. The color sequence and meaning of these 6 color bands are consistent with the EIA standard RS-279, that is, from left to right, the first, second, and third digits are respectively represented, the fourth digit is the accuracy, and the fifth digit is the temperature coefficient. The sixth bit is the voltage coefficient (use only if necessary)

IEC 60062 and EIA RS-279

The IEC 60062 standard and EIA's RS-279 standard are similar, and both specify the marking method of electronic components. However, there are some differences between the two standards.

First of all, the color coding used by the two standards is the same, that is, the 10 colors of black, brown, red, orange, yellow, green, blue, purple, gray, and white. These 10 colors represent the numbers 0 to 9 respectively.

Secondly, the two standards have similar regulations on resistor color coding, using 3 or 6 color bars to indicate resistance value and accuracy. The difference is that the IEC 60062 standard specifies a wider range of applications, while the EIA RS-279 standard is mainly applicable to the US market.

In addition, there are other differences in details between the two standards. For example, the IEC 60062 standard has more detailed regulations on the width and interval of the color bands.

Generally speaking, the IEC 60062 standard can be regarded as an international standard, while the RS-279 standard of EIA is a domestic standard in the United States.