AC Signal Parameters and Core Electronic Components

Fundamental Electrical Signal Parameters

• Cycle: A part of the signal that is repeated.
• Period (T): The time, measured in seconds, that one cycle lasts.
• Frequency (f): The number of cycles repeated per second (Hertz).
• Instantaneous Value: The value of the signal at any given moment.
• Maximum Value (V_max): The greatest signal value within a period (Peak Value).
• Minimum Value (V_min): The smallest signal value within a period (Trough Value).
• Effective Value (V_eff or RMS): The value of an equivalent continuous current that produces the same electrical work. V_eff = V_max / √2

Active and Passive Electronic Components

Active Components

These components are able to generate, modify, or amplify an electrical signal.

Passive Components

Acting as loads, these components only allow the reduction or adjustment of the electrical signal in a circuit.

Resistors and Their Variations

Resistors offer a specific resistance to the passage of electrical current.

Key Resistor Features

• Ohmic value
• Tolerance
• Power dissipation capacity

Variable Resistors

• Potentiometer or Rheostat: Variable resistors that can be manually adjusted.

Nonlinear Resistors (Thermistors and Varistors)

• LDR (Light Dependent Resistor): Resistance decreases as light intensity increases.
• NTC (Negative Temperature Coefficient Thermistor): Resistance decreases as temperature increases.
• PTC (Positive Temperature Coefficient Thermistor): Resistance increases as temperature increases.
• Varistor (Voltage Dependent Resistor): Resistance decreases as voltage increases.

Capacitors: Charge Storage Devices

Capacitors are used to temporarily store electrical charges. They are composed of two conductive plates (armatures) separated by a dielectric (insulating material). The amount of charge they can store (capacitance) is measured in Farads (F), typically microfarads (μF) or picofarads (pF).

Transistor Operation Modes

Transistors typically operate in two main modes:

1. Linear Mode (Active Region)

In this mode, output currents (between emitter and collector) vary linearly with the input voltage at the base terminal. This mode is widely used in analog systems such as amplifiers, analog regulators, and measuring instruments.

2. Switching Mode (Digital Operation)

The transistor acts like an electronic switch, defined by two states:

• Cut-off State (Open/OFF): The transistor does not conduct. The resistance between the emitter and collector terminals is very large (ideally infinite).
• Saturation State (Closed/ON): Maximum conduction. The resistance between the emitter and collector terminals is practically zero.