Electronic Components: Circuits & Devices

Electronic circuits are fundamental systems designed to process information and manage electrical power efficiently.

Structure of Electronic Devices

Electronic devices typically comprise the following functional units:

• Input Devices: Provide the necessary information for the device to function.
• Processing Devices: Control the operation of the device based on the input information.
• Output Devices: Produce end effects, such as visual displays or sound.

These devices commonly include a housing, printed circuit boards (PCBs), and a power supply.

Key Electronic Components

Discrete Components

Discrete components are individual, fundamental units of an electronic circuit. They are categorized into two main types:

• Passive Components: These do not modify the amplitude of the signals they receive. Examples include resistors and capacitors.
• Active Components: These amplify or attenuate signals. Examples include transistors and diodes.

Integrated Circuits (ICs)

Integrated Circuits combine active and passive components interconnected on a single block of semiconductor material, forming microchips. This integration allows for complex functionalities in a compact form.

Resistors

Resistors are passive components that provide resistance to the flow of electrical current. Their resistance value (R) is often calculated using formulas like R = pi / s.

Note: The formula R = pi / s is a simplified representation; typically, resistance is R = ρL/A.

Types of Resistors

• Fixed Resistors: These have a constant resistance value, often marked on the component. They primarily act as current limiting devices.
• Variable Resistors: Their resistance can change based on certain physical parameters. Two common groups are:
  • Potentiometers: Resistance is adjusted manually, often used for volume control or dimming lights.
  • Dependent Resistors: Their strength depends on environmental physical conditions, such as light (photoresistors) or temperature (thermistors).

Capacitors

Capacitors are passive components designed to store electric charge. They typically consist of two conductive plates separated by a dielectric material layer. Their main characteristic is capacitance (C), which represents the amount of electrical charge (Q) they can store in proportion to the voltage (V) applied across them, expressed by the formula: Q = CV.

Capacitor Behavior

• DC (Direct Current): A capacitor allows current to flow only when it is charging or discharging. Once fully charged, it blocks DC current.
• AC (Alternating Current): A capacitor continuously allows the passage of alternating current due to its constant charging and discharging cycles.

Types of Capacitors

• Fixed Capacitors: These have a fixed capacitance value, which is usually marked on the component along with its maximum voltage rating.
  • Electrolytic Capacitors: These have a specific polarity that must be respected during installation to prevent damage.
  • Non-polarized Capacitors: These do not exhibit polarity, meaning the direction of current flow is indistinct.
• Variable Capacitors: These are composed of mobile plates that move via a rotating cursor. This movement changes the surface area facing various plates, thereby altering the capacitor's capacitance.

Capacitors can also function as temporary charge storage devices, similar to small batteries.

Diodes

Diodes are active components that allow electrical current to flow primarily in one direction while blocking it in the opposite direction. They are manufactured using semiconductor materials like silicon and germanium.

A diode has two terminals: the terminal connected to the P-type semiconductor is called the anode, and the terminal connected to the N-type semiconductor is called the cathode.

Types of Diodes

The size and type of a diode often depend on the current it is designed to handle and its specific application:

• Ordinary Diodes: These exhibit the general behavior described (rectification). Various models are optimized for different applications, such as power rectification or signal processing.
• Special Diodes: These offer additional features beyond basic rectification.
  • LED (Light-Emitting Diode): Emits light when current passes through it.
  • Zener Diode: Designed to operate reliably in reverse bias, maintaining a stable voltage across its terminals, often used for voltage regulation.