Inductors color code calculation

Inductors smaller in size are usually surface mounted, their inductance value is written on them with codes or color  codes depending on the manufacturer. In this tutorial we  shall learn how to calculate the inductance of Surface mounted inductors. There are many systems in which inductor's inductance values are printed on them. Most are left blank because they are mostly assembled and  soldered with pick and place machines so no need of printing values on them.  Common systems of calculating and labeling inductors values are explained below.

1. Color code system.

Some inductors usually wound on cylindrical like ferrite core have colors representing a value printed on them. They are usually calculated in the clockwise direction. Like the inductor shown below, 

To calculate the inductance of the inductor above we have to know colors and their codes. Color codes for inductors is similar to that of resistors,

 here are colors and values. 

Color code.            Multiplier. Black.............0......................0 Brown............1......................10 Red................2......................100 Orange..........3.......................1000 Yellow...........4.......................10000 Green............5.......................100000 Blue...............6..................…..1000000 Violet............7....................100000000 Grey..............8....................100000000

White............9....…..........1000000000 

Now that we have known the codes let's calculate the inductance of the above inductor. Taking it clockwisely, we have green, red and orange. The first two colors codes are significant while the last color code is the multiplier. Thus inductance = 52×1000 = 52000nH. Note:  The inductance value must be in nano henries.

2. Letters and figures system.

In this system letters and figures or only figures are printed on inductors to identify their value.

Consider the inductor above, R is placed between numbers. R between numbers represents a decimal point. The inductance of the above inductors is calculated as follows. a.  8R2 =8.2uH. b. 6R8 = 6.8uH. Some inductors are usually labeled with three figures e.g 234, 078. Their value is calculated by writing the first two letters as significant figures and last digit as the multiplier. 

Example.

Calculate the inductance of the inductor below.

Solution.

The code 221 is calculated by writing 22 as significant figures and 1 as the multiplier. The multiplier stands for the number of zeros to be added to the significant figures. Thus, inductance =22×10^1= 220uH.