A quick look at different types of resistors

We have all learned in school about conductors and insulators. A conductor is something that permits electricity to flow freely through it, whereas the insulator does not easily allow current to pass through it.

These characteristics are due to resistance: conductors have a low resistance to the flow of electric current, whereas insulators have a high resistance to the passage of electric current.

There are many different types of resistors, which can be split into two groups: fixed and adjustable resistors (variable resistor).

• Fixed value resistors:

These resistors provide a constant level of resistance in a circuit. Because it is set at a given value, a fixed resistor cannot be modified.

• Variable resistors:

These resistors have a variable resistance value. Variable resistors allow us to vary the resistance value.

Further classification of fixed and variable resistors:

Based on their construction, fixed value resistors are further classified as

• Carbon composition resistors
• Carbon film resistors
• Metal oxide film resistors, and
• Wire-wound resistors

Variable resistors are classified based on how the value of the resistance is modified. This value is determined by the operator or other natural sources. They are categorised as:

• Potentiometer
• Light dependent resistor, and
• Thermistors

• Carbon composition resistors:

These resistors have been around for nearly a century, although they are rarely used nowadays. In comparison to our standard resistors, they are quite huge. Carbon composition resistors are manufactured by combining carbon granules with a binding agent and then converting the mixture into a tiny rod. The ability to endure a high amount of energy pulses is the most significant advantage of these resistors.

They have a number of drawbacks, including large size, noise, a high negative temperature coefficient, and instability. Because of these drawbacks, this type of resistor is no longer utilised or is only used infrequently. They are suitable for usage under RF loads.