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All About the Carbon Composition Resistor


Resistors are a key component of electrical circuits and systems, providing resistance in order to reduce current flow, divide voltages, adjust signal levels, and more. There are also various types of resistors, each providing their own unique benefits and load capacities that cater towards different applications. Carbon composition resistors in particular are a form of fixed resistor, serving as one of the most commonly used types for a wide variety of electrical circuits. In this blog, we will provide an overview of the carbon composition resistor, allowing you to know if it is the right fit for your application.

In general, carbon composition resistors are composed of a cylindrical resistor element that has lead wires attached through embedded wire leads or end caps. To protect the resistor body, it is encapsulated with either paint or plastic, and painting may be present for color-coding. To manufacture the resistive element of the carbon composition resistor, carbon is made into a fine powder and mixed with a ceramic or another insulating material, and a resin binds the mixture. To adjust the amount of resistance that the resistor provides, the ratio of the ceramic to carbon may be changed, and higher amounts of carbon result in a lower value of resistance.

Due to their construction and materials, carbon composition resistors provide a variety of advantages for a number of applications. With the ability to conduct energy throughout its entire body, the carbon composition resistor is capable of withstanding high energy pulses and is thus often used for such circuits. As compared to other resistors, such as wirewound resistors, carbon composition resistors have a larger volume of wires for conducting electricity. As such, they feature a higher energy capability due to an increased thermal mass. Additionally, carbon composition resistors may reach resistive values that are much greater than wirewound resistors, all while remaining much cheaper in price.

Despite these various advantages over other resistors, carbon resistors are not without their drawbacks as well. For one, carbon resistors do not have high stability for their resistance value, and thus they are typically not used for high precision applications. This is due to the variability of resistance that such resistors exhibit, as temperatures, soldering, and other factors may cause values to slightly adjust over time. This change in resistive capabilities is due to the way in which carbon composition materials respond to heat and expand. As the conconducting binder of the resistor heats up and cools down through operation, the body may begin to have stress exerted upon it, and the mechanical contact may change. Due to the materials that are used to construct the resistor, noise levels may also be higher while current is induced throughout the component. Despite these shortcomings, carbon composition resistors are still very beneficial for high energy pulses and are small in size. As such, carbon composition resistors may still be found in a number of circuits for both surge and discharge protection, as well as present use for current limiting, high voltage applications, and welding.

Whether you are in need of carbon composition resistors, wirewound resistors, metal film resistors, or other electronic components, look no further than ASAP Semiconductor. As a leading independent distributor, we can connect customers with the aerospace, defence, medical, IT, and electronic parts and components that they need with competitive pricing and rapid lead-times. We invite you to explore our robust part catalogues at your leisure, and you may begin the purchasing process at any time by filling out and submitting an Instant RFQ form. Once received, a member of our staff will reach out to you in 15 minutes or less to provide a personalized quote based on your individual needs.


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October 23, 2020

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