Fundamental Electronic Components Explained

Resistors: Limiting Current Flow

Resistors are fundamental electronic components that limit and regulate the amount of current flowing through a given circuit. They protect other components by ensuring that a very high current does not circulate through them.

Types of Resistors

Fixed Resistors & Tolerance

Fixed resistors have a constant resistance value. Their tolerance indicates the maximum deviation from their stated value, expressed as a percentage. This value is typically indicated by the first three bands or digits on the component.

Variable Resistors: Potentiometers

Potentiometers are variable resistors commonly used in electronic circuits to create adjustable voltage drops or to control current. Their resistance can be manually changed.

Thermistors: Temperature-Dependent Resistors

• NTC (Negative Temperature Coefficient): If the temperature rises, the resistance decreases. (Temperature ↑, Resistance ↓)
• PTC (Positive Temperature Coefficient): If the temperature rises, the resistance increases. (Temperature ↑, Resistance ↑)

These thermistors are often used in automatic temperature regulation systems.

Light-Dependent Resistors (LDRs)

LDRs are variable resistors whose resistance decreases significantly with increasing light intensity. Their value can change drastically, from thousands of ohms in darkness to only tens of ohms in bright light.

Capacitors: Storing Electric Charge

Capacitors are electronic components capable of storing electric charge and releasing it later. They consist of two metal plates separated by an insulating material called a dielectric. Each plate is connected to a terminal for circuit connection.

The capacitance (C) is the relationship between the electric charge (q) stored by a capacitor and the voltage (V) across it. Its unit is the farad (F).

Where:

• C: Capacitance in farads (F)
• q: Charge in coulombs (C)
• V: Voltage in volts (V)

The charge and discharge time of a capacitor is given by:

Where:

• R: Resistance in ohms (Ω)
• C: Capacitance in farads (F)
• t: Time in seconds (s)

Semiconductors & Diodes

Semiconductors are materials that can be made to conduct electricity under specific external conditions. When a P-type semiconductor is joined with an N-type semiconductor, a diode is formed.

Light-Emitting Diodes (LEDs)

A Light-Emitting Diode (LED) emits light when current flows through it. Its behavior is similar to that of other diodes; it becomes a conductor when it is forward-biased. However, LEDs have the unique characteristic of emitting light when conducting.

The voltage required to make an LED conduct is typically higher than that of a normal diode, approximately 2V, and its operating current is usually around 20mA. LEDs are widely used in various applications, including stereos, televisions, and personal computers.

Transistors: The Core of Modern Electronics

Transistors are among the most important and widely used electronic components. They are composed of three layers of semiconductor material.

Depending on the arrangement of these semiconductor layers, two main types of transistors can be obtained:

• NPN: Consists of Collector / Base / Emitter terminals.
• PNP: Consists of Emitter / Base / Collector terminals.