Types of Resistors – Fixed and Variable

There are two main types of resistors – fixed resistors and variable resistors.

Fixed resistors have a specific resistance value that does not change. They are commonly used in electronic circuits to provide a precise amount of resistance for various applications.

Here are some practical examples of fixed resistors:

  1. Pull-up/pull-down resistors: These are fixed resistors that are used to keep a signal at a specific voltage level when no other input is connected. For example, pull-up resistors are commonly used in digital circuits to keep a signal at a high voltage level when no input is connected.
  2. Current limiting resistors: Fixed resistors are often used in LED circuits to limit the current flowing through the LED to a safe level. For example, if an LED requires 20mA of current to operate and the voltage source is 5V, a 220-ohm resistor can be added in series to limit the current to 20mA.
  3. Voltage dividers: Fixed resistors can be used in voltage divider circuits to produce a specific voltage output from a higher voltage source. For example, a 10k-ohm and a 5k-ohm resistor can be used to produce a 2.5V output from a 5V source.

Variable resistors, on the other hand, allow for the resistance value to be adjusted manually. This makes them ideal for applications where the resistance needs to be varied to adjust the output or response of a circuit.

Here are some practical examples of variable resistors:

  1. Volume control: Variable resistors, also known as potentiometers, are commonly used in audio equipment to adjust the volume level. By adjusting the resistance of the potentiometer, the amount of current flowing through the amplifier can be adjusted, which in turn adjusts the volume.
  2. Temperature control: Variable resistors can be used in temperature control circuits to adjust the amount of resistance in a thermistor. As the temperature changes, the resistance of the thermistor changes, which can be used to control the output of a circuit.
  3. Light dimmer: Variable resistors can be used in light dimmer circuits to adjust the brightness of a light source. By adjusting the resistance of the variable resistor, the amount of current flowing through the light can be adjusted, which in turn adjusts the brightness.

Overall, understanding the different types of resistors and how to use them effectively is crucial for designing and maintaining reliable and long-lasting electronic circuits.