Resistors are one of the most basic yet indispensable components in electronics. Whether you’re designing a simple LED circuit or a complex microcontroller-based system, resistors are almost always involved. But what exactly does a resistor do? And why are there so many types?
What is a Resistor?
A resistor is a passive component that opposes the flow of electric current. It works on the principle of Ohm’s Law, which states:
V = IR
Where V is voltage, I is current, and R is resistance.
Resistors are used to:
- Limit current in a circuit
- Divide voltages
- Bias active components like transistors
- Pull-up or pull-down inputs in logic circuits
Types of Resistors:
- Carbon Film Resistors: Affordable, but not very precise.
- Metal Film Resistors: Higher accuracy and stability.
- Wire-Wound Resistors: Handle high power, usually larger in size.
- SMD Resistors: Surface-mounted for compact designs.
Key Specifications:
- Resistance (Ohms): The value of opposition to current.
- Tolerance (%): How accurate the resistance is.
- Power Rating (Watts): How much heat it can dissipate safely.
- Temperature Coefficient: Change in resistance with temperature.
Applications:
- LED circuits
- Voltage dividers
- Power supply filters
- Audio attenuators
Understanding resistor color codes and using resistor calculators makes working with them easy for both hobbyists and professionals.
