Definition, Working of Carbon Resistors

To regulate the current flow in the circuit, we need specific resistance. Carbon composition resistors are ideal for fitting to resist the current to specified levels. Hence, they are also known as the fixed form of a resistor. However, metal wires like copper, aluminium and iron have resistances, but we can’t use them directly in circuits. It is because the resistance they offer is meagre, and the cost of the metal is very high.

Furthermore, the conductor provides light resistance, whereas the inductor provides very high resistance. To get the desired resistance in the circuit, we need a material to calibrate or measure its resistance to get a specific force. Moreover, they should be low in cost. All these qualities make carbon an ideal material for resistance.

What is a Carbon Resistor? 

The carbon resistor is a thin and small carbon powder cylinder with a metal coating or metal jacket with metal wires. In other words, carbon resistors are resistors made out of small carbon fragments bound together by an adhesive and backed with a terminal wire on either end. 

Carbon resistors are often used to regulate resistance so that they may provide a high level of accuracy. In addition, they’re cheap, compact, and may be placed straight on circuit boards like those used in tablet devices, smartphones, and laptop CPUs. 

Carbon resistors are tiny packets of resistance linked to the circuit to limit current flow by a certain amount. Metal caps act as cooling channels for small resistances required for small currents, drawing energy dissipation from the resistor and transferring it to the metal cap. 

A metal heat sink is attached separately for higher current demands to remove excess heat and protect the resistor from catching fire.

Working on Carbon Resistors

Five fundamental blocks fabricate this fixed form of a resistor: the ceramic core, nickel cap, carbon film, lead, and protective epoxy layer. The fabrication of carbon resistors includes the deposition process. A bulk of fine carbon particles are combined with clay to manufacture carbon resistors. 

It takes a solid shape after baking. Despite the widespread use of carbon composition resistors in circuits, the manufacturing of bulk resistors takes place by depositing a metal or carbon film above a binding medium. Carbon resistors fit in an electronic circuit to induce a certain amount of resistance on the circuit board. 

Uses Of Carbon Resistors

There are numerous applications of carbon resistors in our practical life. Some of the most common are as follows:

• Carbon resistors carry a small size, but they are highly efficient to withstand high energy pulses. That quality increases their use in manufacturing various electronic appliances we use daily.
• They are suitable for working with temperatures approx 350 degrees and higher voltages up to 15K Volt.
• The carbon resistor is helpful in the high voltage power supply of Lasers, X-rays, and radar systems.
• Circuit protection from surge or discharge, current limiting, high voltage power supply generating, high power or strobe lights, and welding are actual examples of carbon resistors.
• A medical defibrillator is the best example of its application. High energy pulses of roughly 30 Joule must remain fixed against sensitive measuring equipment attached to the patient.

Explain How Carbon is a Preferable Material in Resistor Manufacturing

Carbon composition resistors have the benefit of being able to endure high-energy pulses. This is because the whole carbon composition body conducts the energy when current travels through the resistor. 

Carbon film resistors often have 5, 10, and 20% tolerances. The carbon film resistor has a more significant negative temperature coefficient than carbon composition due to the usage of pure carbon. Between 2.5 x 10-4 and -8 x 10-4/°C is the resistive temperature coefficient. Hence, carbon is a preferable material in resistor manufacturing. 

Advantages of Carbon Resistors

The advantage range of carbon resistors includes:

• Carbon-based resistors have the benefit of being able to endure high-energy pulses.
• The whole carbon composition body conducts the energy when current travels through the resistor. As a result, the carbon composition resistor has an appreciably larger thermal mass, resulting in a higher energy capacity.
• Carbon resistors have more excellent resistance than wire-wound resistors and are significantly less expensive.

Conclusion

All the electronics and electrical circuits are complex in nature and structure. Generally, they are a combination of different registers, capacitors, inductors, and voltage sources either in linear, parallel, or hybrid arrangements. Therefore, carbon composition resistors offer many benefits in designing electric or electronic circuits. 

They have reduced other numbers of conductors and inductors in the circuit and hence the complexity of the circuit too. However, they are less stable due to the bulk of carbon but more economical, easy to calibrate and long-lasting.