Introduction
In the world of electrical and electronics engineering, basic electrical components are the foundation of almost all the systems and devices we use every day. Without a solid understanding of basic components such as resistors, capacitors, and inductors, it is very difficult to design, repair, or understand how an electrical circuit works.
Resistors, capacitors, and inductors are three primary passive components that play a vital role in controlling current and voltage in an electrical or electronic system. Each component has its own unique operating principle and application, and complement each other in various circuit designs.
In this material, we will discuss these three components in depth, starting with their definitions, operating principles, units, types, and their applications in everyday life. It is hoped that after studying this material, readers will understand the important role of each component and be able to use them effectively in electronic circuit design.
1. Resistors
1.1 Definition and Function
A resistor is a passive electronic component designed to oppose the flow of electric current in a circuit. Its purpose is to regulate the amount of current flowing and adjust the voltage at specific points in the circuit.
Simply put, a resistor works like a water faucet: the greater the resistance, the less current flows through it. Resistors do not store energy like capacitors or inductors, but instead convert some of the electrical energy into heat.
1.2 Units and Symbols
The unit of resistance is the Ohm (Ω), named after the scientist Georg Simon Ohm. The value of a resistor determines its resistance to current.
The symbol for a resistor in an electrical circuit schematic is:
- Standard resistors:─[Ω]─
- 1.3 Ohm's Law
The relationship between voltage (V), current (I), and resistance (R) is expressed in Ohm's Law:
V : (Voltage)
I : Current (amperes)
Resistance (ohms)
1.4 Types of Resistors
- Fixed Resistors
Their value cannot be changed. They are used to limit current and set voltage.
- Variable Resistors (Potentiometers/Trimpots)
Their value can be adjusted manually. They are often used in radio volume controls or light intensity controls.
- Thermistors (Thermally Sensitive Resistors)
Their value changes with temperature. There are two types:
- NTC (Negative Temperature Coefficient): Resistance decreases as temperature increases.
- PTC (Positive Temperature Coefficient): Resistance increases as temperature increases.
- LDR (Light Dependent Resistors)
Their value changes with light intensity. They are often used in automatic lights or light meters.
1.5 Resistor Applications
- Controlling the current to LEDs to prevent burnout.
- Adjusting the voltage level for sensor inputs.
- As part of a voltage divider circuit.
- Adjusting the frequency in combination with a capacitor in an oscillator.
2. Capacitors
2.1 Definition and Function
A capacitor is a passive electronic component that stores electrical energy in the form of an electric field. This energy is stored in the form of a charge on two conducting plates separated by an insulating material (dielectric).
Capacitors do not allow continuous current flow through them, but they can conduct current for short periods during charging and discharging.
2.2 Units and Symbols
The unit of capacitance is the farad (F), named after Michael Faraday. However, in practice, smaller units are used, such as microfarads (μF), nanofarads (nF), or picofarads (pF).
Capacitor symbol:
- Kapasitor non-polar : ─||─
- Polar capacitor (electrolyte) : ─|(|─
2.3 Basic Formula
The charge (Q) stored by a capacitor is formulated as follows:
Description:
- Q = Charge (Coulombs)
- C = Capacitance (Farads)
- V = Voltage (Volts)
In an AC circuit, a capacitor has a reactance (Xc) that affects the current flow:
2.4 Types of Capacitors
1. Electrolytic Capacitors
Polar, have a large capacitance. Suitable for power supply applications.
2. Ceramic Capacitors
Non-polar, small size, for high frequencies.
3. Film Capacitors (Polyester/Polypropylene)
Withstand high currents and high voltages.
4. Tantalum Capacitors
Stable and reliable, but quite expensive.
2.5 Functions and Applications
- Filters in power supplies.
- Signal coupling in audio amplifiers.
- Time processing (timer) with resistors.
- Provides temporary power backup during voltage drops.
3. Inductors
3.1 Definition and Function
An inductor is a component that stores energy in the form of a magnetic field when current flows through it. Consisting of a coiled wire, an inductor opposes changes in current.
Inductors are often called coils, and their operating principle is closely related to Faraday's law of electromagnetism.
3.2 Units and Symbols
The unit of inductance is the Henry (H). Its symbol in electrical schematics is:
Standard coil: ─⎍⎍⎍─ or turn symbol
3.3 Induction Formula
The voltage induced in an inductor is formulated as:
Description:
- V = Voltage (volts)
- L = Inductance (henry)
- dI/dt = Rate of change of current over time
3.4 Types of Inductors
1. Air Core Inductors
Used for high frequencies, non-saturated.
2. Iron/Ferrite Core Inductors
Used in power circuits, such as transformers.
3. Toroid (ring-shaped)
Efficient, with a closed magnetic field.
3.5 Functions and Applications
Used as a filter in power supplies (LC filter).
Main component in transformers.
Energy storage in DC-DC converters (buck or boost converters).
Used in radio tuners to select specific frequencies.
4. Combined Applications in Circuits
In the real world, these three components are often used together in various types of circuits:
- RC and RL filters: Filter signals based on frequency.
- Oscillators: Generate periodic waveforms (using LC or RC).
- Power supplies: Rectifiers, filters, and regulators.
- Sensors and actuators: Regulate system response based on signals.
5. Conclusion
An understanding of resistors, capacitors, and inductors is essential for anyone wishing to master electronics or electrical engineering. By mastering the working principles and applications of these three basic components, one can more easily analyze, design, and repair various electronic circuits, from simple to complex.
These three components, although seemingly small and simple, play a vital role in regulating, controlling, and directing electrical flow as needed.
Post a Comment