Carbon Resistor vs. Wire Wound Resistor: Key Differences

This page highlights the fundamental differences between carbon resistors and wire wound resistors. As we know, a resistor is a device that impedes the flow of electric current. Its resistance is measured in Ohms. Here’s a breakdown of these two common types:

Carbon Resistor

A carbon resistor is made primarily of carbon or graphite.

Advantages of Carbon Resistors

• Small Size & Lightweight: They are physically compact and don’t add much weight to a circuit.
• Suitable for High-Frequency Circuits: Carbon composition allows them to operate effectively in high-frequency applications.
• Low Temperature Coefficient: Their resistance changes relatively little with temperature fluctuations.
• Easy to Manufacture High Values: Creating high-value resistors is simpler with carbon composition.

Disadvantages of Carbon Resistors

• Susceptible to Environmental Changes: Their resistance can be affected by changes in temperature and humidity.
• Limited Power Handling: The current carrying capacity, and therefore the power (wattage) they can handle, is limited to around 2 Watts.
• Difficult to Manufacture Low Values: Making carbon resistors with values less than approximately 2 Ohms is challenging.
• Poor Stability & Reliability: Compared to other types, carbon resistors aren’t as stable or reliable over time.

Carbon resistors come in two primary forms: composition type and film type.

Wire Wound Resistor

A wire wound resistor is constructed by winding a wire (typically a high-resistance alloy) around an insulated core.

Advantages of Wire Wound Resistors

• High Stability & Reliability: They offer excellent stability and consistent performance over long periods.
• High Power Rating & Low Tolerance: They can handle significant power and are manufactured with precise resistance values (low tolerance).
• Easy to Manufacture Low Values: Creating wire wound resistors with values as low as 0.01 Ohm is readily achievable.

Disadvantages of Wire Wound Resistors

• Difficult to Manufacture High Values: Making wire wound resistors with values in the Mega Ohm range is difficult.
• Difficult to Create Variable Types: Constructing variable wire wound resistors is more complex than with other types.
• Not Suitable for High-Frequency Circuits: Their inductive properties make them less suitable for high-frequency applications.
• Large Size: They tend to be physically larger than carbon resistors, which can be a limitation in some applications.

The wire wound resistor is also commonly known as a rheostat when used as a variable resistor.