Resistor Colour Codes

Resistor Colour Code Chart

A resistor colour code was introduced in the year of 1920. These color bands are printed on the body of tiny resistor components. For color codes, we can employ the resistor mnemonic called BBROY Great Britain Very Good Wife, where the beginning letter points to a unique colour.

All the electrical components and wires are coded are with colors to identify their value and function. We use the following colours as tolerance codes on five-bands only because of which the five-band resistors are called colored tolerance bands:

• Red

• Brown

• Green

• Blue

• Violet

A resistor has many color bands, where each band carries a specific purpose and function, so let’s discuss the resistance color code chart:

Resistor Color Code Table

The table below shows the resistor colour codes:

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As I discussed, each resistance color code has a tolerance value, let’s see what are these:

Resistor Colour Code Calculator

The below table a shows the carbon resistor colour code:

Now, let’s discuss the resistor color coding formula:

For calculating the resistance colour code calculator, we need to group the values of the significant digits bands; it means we will take the values of the first two or three bands from the left, depending on the total number of bands, then we will multiply that value by the multiplier to get the resistance value of the resistor.

Let's suppose that we take a four-band resistor with the following band colors: 

Violet

Green

Yellow

Gold

The first two colors in the four-band resistor, viz: violet and green indicate the significant digits (i.e., 75) which are according to the above table (a).

Now, we will multiply that number by the multiplier indicated with the third band, i.e., yellow and it has the value of 10⁴ or 10000.

So the multiplication will be: 75 x 10000 = 750000 Ω 

So, the minimum value is 750 kΩ or 75 10⁴ Ω.

The fourth band, i.e., gold indicates the tolerance of  ±5% (as given in table a).

Now, to calculate the minimum and maximum resistance values, we need to multiply the resistance value by the tolerance percentage to obtain the following values:

Minimum = 750000 - (750000 x \[\frac{5}{100}\]) 

= 750000 - 37500 = 712500 = 712.5kΩ

Maximum = 750000 + (750000 x \[\frac{5}{100}\]) 

= 750000 + 37500 = 787500 

So, the maximum value is 787.5kΩ

What is a Resistor?

We define a resistor as a passive two-terminal electrical component that is used as an electrical resistance viz: an element of the circuit. In electronic circuits, resistors are used to reduce the flow of current through the circuit, they are also used to perform the following operations:

• Adjust signal levels, 

• Divide voltages, 

• For biasing the active elements, 

• Terminate the transmission lines and many more places. 

Types of Resistors

There are two types of resistors; these are as follows:

1. Linear resistors

2. Nonlinear resistors

A. Resistors whose value varies with the change in the applied temperature and voltage are called linear resistors.  Linear Resistors are of two types, viz: fixed resistors and variable resistors, let’s discuss their types:

• Fixed Resistors:

A fixed resistor has a fixed specific value that means its value cannot change whatever the conditions it is being subjected to. Fixed resistors are of the following types:

1. Carbon composition resistors 

2. Wire wound resistors

3. Thick film resistors

Thick film resistors are of the following types:

1. Fusible resistors 

2. Cermet film resistors

3. Metal oxide resistors

4. Thin-film resistors 

Thin-film resistors are of the following types:

1. Carbon film resistors

2. Metal film resistors

• Variable Resistors:

The value of variable resistors can be varied with the help of a dial, knob, or screw. We can find their applications in radio receiving stations for controlling volume and tone. Variable resistors are of the following types:

1. Potentiometer

2. Rheostat

3. Trimmer resistors 

B. Resistors whose value can vary according to the temperature or voltage applied to these; however, these resistors do not follow Ohm’s law. Nonlinear resistors are of the following types:

• Thermistor

• Photoresistor LDR

• Varistor resistors

• Surface-mount resistors