Resistors are passive electronic components that resist the flow of electric current within an electronic circuit. Below we discuss the types of resistors.
The main categorizations of resistors are fixed resistors, variable resistors, specialized resistors, surface mount resistors, and high-power resistors.
There are different types of resistors under each of the above categories and each type is different from the other and performs a certain function within a circuit.
In addition, it is worthwhile to note that in some types of resistors, the resistance value is calculated via a color code system printed on the specific resistor.
Each color has a numerical value that helps in determining the resistance and tolerance of a resistor. Below we uncover resistors in detail.
Kindly read through. By the end of this article, you will additionally learn more about the functions, characteristics, and all the types of resistors.
Characteristics of Different Types of Resistors
Before we proceed, let us learn in detail the characteristics of different types of resistors.
Resistance Value (Ohms – Ω)
Resistance is the primary property of a resistor and is measured in ohms (Ω) and is defined as the opposition to the flow of electric current.
Resistors are designed to have specific resistance values and these values are typically marked using numerical labels or color codes.
Tolerance
Tolerance is the allowable deviation from the specified resistance value mainly within 5%, 1%, and 0.1%. An example would be a 100 ohm resistor with a 5% tolerance.
This means that the resistor could have a resistance of between 95 ohms to 105 ohms.
Power Rating (Watts – W)
The maximum power that a resistor can dissipate as heat without overheating or getting damaged can be specified as the power rating.
Resistor power ratings are measured in watts and typically begin at 1/8 watts, then 1/4 watts to several watts…
Temperature Coefficient
Temperature coefficients in some resistors which could be positive or negative values indicate how their resistance changes with temperature.
Functions and Applications of Resistors
As with any other electronic components, resistors do have their functions and applications. In this section, we shall delve into this.
Current Limiting
This is the core function of a resistor. A resistor limits the flow of electric current in a circuit and this helps prevent damage to other components or devices within a circuit due to excessive current.
Voltage Division
In voltage divider circuits resistors are used to create reference voltages or reduce voltage levels in specific portions of a circuit.
This is important in applications that require signal conditioning and sensor calibration.
Temperature Sensing
Thermistors among other resistor types exhibit resistance changes with temperature and are used in temperature measurement and control applications.
Signal Conditioning
Modifying and conditioning signals, resistors can be part of filters, attenuators, and voltage dividers, shaping the characteristics of electrical signals.
Timing Circuits
In combination with capacitors, resistors can be used to create time constants and set time delays in various timing circuits.
Pull-Up and Pull-Down Resistors
These resistors are used to ensure that digital inputs in microcontrollers and digital logic circuits have defined logic levels (high or low) when external devices are not actively driving the input.
Load Balancing
In parallel circuits, resistors are used to balance loads and ensure that each branch of the circuit receives the appropriate amount of current.
Voltage Dropping
In power supply circuits, resistors are used to reduce voltage levels when the input voltage exceeds the desired level.
Types of Resistors
Now that we have learned about the characteristics, functions, and applications of resistors, let us get to learn more about resistor types below.
Fixed Resistors
These are the most common resistors. Their resistance is fixed and can not be adjusted. In addition, fixed resistors come in various physical forms that include:
- Through Hole Resistors
- Surface Mount Resistors, and
- Axial Lead Resistors
Fixed resistors come in different types like carbon composition resistors, metal film resistors, wire-wound resistors, thick film resistors, and thin film resistors. we discuss them in detail below…
Carbon Composition Resistors
Consisting of carbon and other insulating materials, carbon composition resistors are the oldest types of resistors and are relatively cheap.
In addition, they are more stable than other types but on the other hand, they are less precise. They are commonly used in basic electronic applications.
Metal Film Resistors
These resistors are made by depositing a thin film of metal such as tantalum nitride or nickel-chromium into a glass substrate or ceramic.
Furthermore, metal film resistors offer stability, precision, and low noise characteristics making them very common. They are found in many electronic applications.
Metal Oxide Film Resistors
Similar to metal film resistors, metal oxide film resistors are made of metal oxide coating as opposed to pure metal coating.
In addition, they offer better overload capacity and temperature stability thus suitable for high-power applications.
Wirewound Resistors
Used in power electronics and precision measurement, wire-wound resistors offer stability, precision, and high power handling capabilities.
They are made by winding a resistance wire, usually made of nichrome (nickel-chromium alloy), around a ceramic or fiberglass core.
Thick Film Resistors
Thick film resistors are made by depositing a paste of resistive material on a ceramic substrate and then curing it.
Additionally, they are cost-effective and suitable for general-purpose applications.
Thin Film Resistors
Made by sputtering a thin layer of resistive material onto a ceramic substrate, thin film resistors offer low-temperature coefficient, low noise, and high precision making them ideal for precision and high-frequency applications.
Variable Resistors (Potentiometers)
Also referred to as potentiometers, variable resistors are adjustable and can offer a variable resistance value. They have a knob attached to them as well.
Rotating the knob or sliding the slider can help you to adjust the resistance value. You will get these resistors being used as volume controls, tuning circuits, and for setting voltage references.
Final Thoughts
Resistors are available in various physical forms, including axial-lead resistors, surface-mount resistors, and through-hole resistors, making them versatile and adaptable to a wide range of circuit design requirements.
They are essential components for controlling current and voltage levels in electronic circuits, ensuring the proper operation and safety of electronic devices.
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