Colour Code for Carbon Resistors

Introduction

A current is slowed by resistance, which is an electric property. A current flowing through a wire (or resistor) is analogous to water running through a pipe, and the voltage drop across the wire is analogous to the pressure drop that forces the water through the pipe. Conductance is proportional to how much flow occurs for a given pressure, whereas resistance is proportional to how much pressure is necessary to accomplish a given flow. What factors influence resistivity? The resistivity of various materials differs dramatically. Teflon, for example, has a conductivity that is roughly 1030 times lower than copper. What’s the deal with the disparity? How to understand the colour code for resistors? In a nutshell, metal has a lot of “delocalized” electrons that aren’t fixed in one place and can move around freely, but in an insulator (like Teflon), each electron is strongly linked to a single atom requires a lot of force to move around.

Resistors

 A resistor is an electrical component that causes resistance in current flow. They can be found in practically all electrical networks and electronic circuits. Resistance is expressed in ohms (). When one ampere (A) current passes through a resistor with one volt (V) drop across its terminals, the resistance is measured in ohms. The voltage across the terminal ends determines the current. Ohm’s law can be used to express this ratio:

 R = V / I

 Resistors are utilized in a variety of applications. Examples include limiting electric current, voltage division, heat generation, matching, loading circuits, gain control and time constant setting. They can be smaller than a square millimetre for electronics or used as electric brakes to dissipate kinetic energy from trains.

 Resistor Specifications

 Resistor specifications are as follows:

 Value of resistance

1. Tolerance
2. Rating of strength
3. Thermal Constancy

1) Ohmic value (resistance value):

The resistance value is used to express the magnitude of the resistor. The resistance value determines the amount of current flow that is opposed. As a result, resistance is measured in ohms, kilo-ohms, or mega-ohms. The resistance value is printed on the resistor’s surface or indicated by colour bands.

2) Wattage Rating (Power Rating):

 The maximum power in watts that the resistor can handle without being destroyed or damaged is specified by its power rating. In terms of I2R loss, it also indicates the power dissipation in the resistor (or heat).

3) Tolerance: 

Tolerance represents a resistance value’s maximum and minimum values. It is expressed in percentage terms. On the surface of the resistor, it is indicated as a percentage.

4) Thermal Stability: 

Thermal stability is the resistance value’s consistency at a given maximum temperature. Or a resistor can keep the same resistance value despite temperature changes.

 Resistor Symbol and Definition

 A resistor is a passive electrical component whose ultimate purpose is to restrict the flow of electric current.

The illustration to the left illustrates that the international IEC sign is rectangular with leads at either end. The ANSI standard, which depicts a fixed resistor as a zigzag line, is widely used in the United States (shown on the right)

When a circuit design is produced, there are different symbols of resistors.

 Characteristics of Resistor

 The resistor tolerance indicates the manufacturing accuracy of this value and is given as a percentage of the resistance value (for example, 5%). Various other characteristics that affect the resistance value, such as long-term stability and temperature coefficient, can be specified. The resistive material and the mechanical design determine the temperature coefficient, frequently stated in high precision applications.

 High-frequency circuits, such as radio electronics, can have undesired parasitic capacitance and inductance. Wirewound resistors have the highest parasitic reactance, while foil resistors have the lowest. The resistor’s electric noise must be kept minimum for precise applications such as audio amplifiers. The power rating is critical for high-power applications. The power rating is given in free air at ambient temperature in most cases. Higher power ratings require larger size and heat sinks. This is important in situations where significant voltage surges may occur.

 In some cases, the designer must consider the electrical qualities and the mechanical robustness in severe settings.

Types of Resistors

 Various types of Resistors are available in a wide range of sizes, shapes, and materials. As follows, we’ll go through each possible resistor type in detail, including pros and downsides, as well as applications. Resistors are divided into two categories.

1. Linear Resistors
2. Non-Linear Resistors

Linear Resistors:

 Linear resistors are resistors whose values fluctuate with the applied voltage and temperature. In other words, resistors with a current value proportional to the applied voltage are known as linear resistors.

Non-Linear Resistors :

As we all know, non-linear resistors are resistors whose current flowing through them does not fluctuate according to Ohm’s Law but instead changes with changes in temperature or applied voltage.

Furthermore, Thermistors are resistors whose flowing current changes in response to changes in body temperature. Varistors, or VDRs, are resistors that alter their flowing current when the applied voltages change (Voltage Dependent Resistors).

Resistor colour codes

Colour codes for resistors employ coloured bands to instantly identify a resistor’s resistive value and tolerance percentage, with the resistor’s physical size indicating its wattage rating.

When the resistor’s body is large enough to see the print, such as large power resistors, the resistance value, tolerance, and wattage rating are usually displayed as numbers or letters on the resistor’s body.

Several coloured bands around the component body represent the resistance value and tolerance. This electronic component labelling approach was first developed in the 1920s. Because printing technology was still in its infancy, printing number codes on small components was impossible. The colour scheme is still used today for most axial resistors up to one watt.

 To read colour codes for resistors showing numerical values, distinct colour bands are printed on the left end of the resistor’s body in this way. The table includes a colour code chart (A).

Hold the resistor so that the colour bands begin on the left side.

From left to right, read the colour bands.

The first band displays the resistance value’s initial digit.

The second hand represents the double-digit, while the third band represents the multiplier or the number of zeros added after the second digit.

The fourth band shows the percentage tolerance.

Conclusion

Resistors are used to block the flow of electric current in a circuit. As a result, the resistance value is their crucial parameter. For each application, the manufacturing tolerance must be carefully selected. For various reasons, the final resistance value may differ from the specification. The temperature coefficient of resistance, or TCR, is one example, which is frequently defined for precision applications. The term “stability” refers to the resistance’s long-term fluctuation. The resistance value may not revert to its initial value after an extended period of electric load. Every resistor has electric noise, a significant feature for low-noise amplifying applications. The parasitic inductance and capacitance properties are essential in high-frequency applications.

The maximum power and voltage can be chosen in addition to resistance-related factors. The maximum rated voltage must be considered in high voltage circuits. For some applications, the longevity and reliability of a resistor are more critical than for others. The following is a list of the most common resistor attributes and characteristics. A detailed overview of the resistor’s characteristics and colour