Carbon Resistors

A resistor is a two-terminal passive electrical component that acts as a circuit element by putting electrical resistance into the mix. Resistors are used in electronic circuits to cut down on current flow, adjust signal levels, divide voltages, bias active elements, and end transmission lines, among other things. To make the resistance, a lot of different metals and alloys are used, like nichrome, brass, platinum, and tungsten. If you compare metal resistors to carbon resistors, you’ll find that most of them have low electrical resistance because it’s hard to make high resistance without making the resistor bigger, which makes them less efficient.

To measure resistance, carbon resistors are used a lot. Carbon resistors can give a very precise value of resistance. They are cheap, small, and maybe built into circuit boards used in tablets, smartphones, and laptop CPUs. Metal wires are more expensive than carbon, which can be found in a lot of places, so they are chosen for all of these practical reasons.

Carbon resistors 

Carbon Resistors are the most common type of Composition Resistors. They are also the most common. Carbon resistors are a cheap type of resistor that can be used in both electrical and electronic circuits. With their resistive element, they mix finely ground graphite (like pencil lead) with a non-conducting clay powder to make it all stick together. The overall resistive value of the mixture is determined by the ratio of carbon dust to ceramic (a conductor and an insulator). The more carbon there is, the lower the overall resistance of the mixture will be. In this example, the mixture is molded into a cylindrical shape with metal wires or leads attached to each end to make an electrical connection as shown. Then, it is covered with an outer insulating material and color-coded markings to show how much resistance it has, as shown.

Parts of carbon resistors 

Carbon resistors can be made of a lot of different things, but below are some of the carbon resistor’s parts.

Ceramic core

Nickel Cap

Carbon film

Lead

Protective epoxy layer

Working of carbon resistors 

There must be the right amount of resistance on the circuit board when making an electric or electronic circuit for a certain use. It is done by using carbon resistors, which are small parts. These parts are small packets of resistance that are connected to the circuit to stop the flow of electricity by a certain amount.

Carbon is put on top of a ceramic core in a carbon resistor. As it cools, the carbon that has been put down is etched away in a spiral. This makes it into a wire that is wrapped around a ceramic core. The pitch, diameter, and length of the carbon spiral all change depending on how much resistance you need from it. There are nickel caps that go on both ends of the core to make sure that the carbon and lead are in good contact.

Advantages and disadvantages of carbon resistors 

Carbon composition resistors have a big advantage over other types of resistors because they can handle very high-energy pulses. When electricity flows through the resistor, the whole carbon composition body moves the energy. Wirewound resistors, for example, use a lot less wire to move electricity. So, the thermal mass of the carbon-based resistor is much higher, which means it can store more energy. Wirewound resistors are more expensive than carbon resistors, but carbon resistors can be made with more resistance and are much cheaper. However, the temperature coefficient, noise, voltage dependence, and load aren’t as good as they could be.

Fifty years ago, carbon composition resistors were used in a lot of home electronics. Because the resistance value isn’t very stable, this type of resistor isn’t good for any high-precision applications today. It can change up to 5% over a year. With a lot of use, the value changes even more: up to 15% for a 2000-hour test at full power with a 70°C ambient temperature. Soldering can make 2% more of a difference.

Because of the way the resistor is made, this instability is a given. Carbon is made up of different materials that expand at different rates when heated. When the conducting carbon particles and the non-conducting binder heat up or cool down, the resistor body gets stressed. Mechanics will change, which means the resistance value will go up or down.

Also, the noise properties of carbon composition resistors are bad because they are made of a lot of different things. When there are a lot of currents, the noise level goes up. There are resistors that can withstand voltages of 0.25 W and 0.5 W. They can withstand voltages of 150 V and 500 V. If you connect two wires together, the resistance between them is very low (approximately an order of magnitude worse than other types). It’s also less common to use this type of resistor because it has a high-temperature coefficient of about 1200 ppm/°C, which is why it’s less common. -40 to 150 °C is the range in which the machine can be used. However, the resistors aren’t as strong above 70 °C.

Uses of carbon resistors 

1. Because the carbon resistor can withstand high-energy pulses despite its small size, it can be used in a lot of different things in everyday life.
2. Up to 350°C and 15KV can be put through the resistor, and it can withstand both of these things.
3. X-rays, radar, and lasers all use carbon resistors to get their power.
4. Defibrillators and other patient-attached equipment that needs to be protected from high-energy pulses also use this type of material.

Conclusion 

A resistor is a two-terminal passive electrical component that acts as a circuit element. They are used in electronic circuits to cut down on current flow, adjust signal levels, divide voltages, bias active elements, and end transmission lines. Carbon resistors are the cheapest and most common way to measure resistance. These parts are small packets of resistance that are connected to the circuit to stop the flow of electricity. Carbon resistors have a big advantage over other types of resistors because they can handle very high-energy pulses.

Resistor resistance can vary by up to 15% for a 2000-hour test at full power with a 70°C ambient temperature. Soldering can make 2% more of a difference. There are resistors that can withstand voltages of 0.25 W and 0.5 W.