Electronics Fundamentals

Posted on Feb 10, 2025 in Technology

Alternating Current (AC)

AC is a variable current where the electron flow changes direction periodically, resulting in varying voltage values.

Advantages of AC:

Suitable for household power distribution.
Minimizes transmission losses.

Key Concepts:

Cycle: A repeating part of the signal.
Period: Time duration of one complete cycle.
Frequency: Number of cycles per unit of time.
Instantaneous Value: The voltage or current at any given moment.
Effective Value: The equivalent DC value producing the same power.

Resistance

Resistance is the opposition to the flow of electric current. It represents the orderly movement of electrons through a conductor.

Ohm’s Law: Ohm’s Law defines the relationship between voltage, current, and resistance.

Types of Resistors:

Fixed: Standard resistors with a constant value.
Special: Potentiometers, LDRs, NTCs, PTCs (variable resistors).

Key Properties:

Tolerance: The difference between the theoretical and actual resistance values.
Power Rating: The amount of energy dissipated as heat.

Resistor Color Codes

Black: 0, x1
Brown: 1, x10
Red: 2, x100
Orange: 3, x1000
Yellow: 4, x10000
Green: 5, x100000
Blue: 6, x1000000
Violet: 7, x10000000
Gray: 8, /10
White: 9
Silver: /100
Gold: /10

Capacitors

A capacitor is a component that stores electrical charge temporarily. Capacitance is measured in Farads (F). Common submultiples include microfarads (µF) and nanofarads (nF).

Diodes

Diodes are electronic components that allow current to flow in only one direction.

Doping: The process of adding impurities to a semiconductor to alter its electrical properties.

Forward Bias: When a positive voltage is applied to the anode and a negative voltage to the cathode, the diode conducts.

Diodes are commonly used in power supplies to rectify AC to DC.

Light Emitting Diodes (LEDs)

LEDs are diodes that emit light when current flows through them.

Advantages:

High energy efficiency
Low heat production
Long lifespan
Small size
Durable
Variety of colors
Low power consumption

Transistors

A transistor is a three-terminal semiconductor device (emitter, base, collector) used for amplification and switching.

Types:

Transistor Circuits:

Control Circuit
Main Circuit

Modes of Operation:

Nonlinear (Switching):
- Open: High collector-emitter resistance (like an open switch).
- Closed: Low collector-emitter resistance (like a closed switch).
Linear (Amplification): Output voltage and current are proportional to the input, enabling functions like dimming a light bulb.

Integrated Circuits (ICs)

Also known as chips, ICs are miniaturized electronic circuits consisting of interconnected components (diodes, transistors, resistors, capacitors, etc.) on a semiconductor material.