Essential Electronic Components and Circuit Measurement

Fundamental Electronic Components and Measurement

Resistors: Function and Characteristics

Resistors are components that offer opposition to the passage or circulation of electric current, causing a potential voltage drop across their terminals. Key characteristics include:

• Ohmic resistance magnitude and tolerance (limiting deviations established by the manufacturer).
• Power rating (the maximum power the resistor can safely dissipate).

Resistors must operate under stable conditions.

Types of Resistors

Fixed Resistors

These components maintain a constant ohmic value and typically have two terminals. Their resistance value is often obtained by modifying carbon layers using a spiral cut that forces the electric current to follow a specific, calculated path.

Variable Resistors

These components have the capacity to vary their ohmic value within specified limits. They are broadly categorized into potentiometers and dependent resistors.

Potentiometers (Linear Variable Resistors)

Potentiometers operate based on a sliding contact mechanism. Depending on the position of the slide, the resistance can vary linearly between 0 and the maximum resistance (R $\Omega$).

Dependent Resistors (Sensors)

These components are manufactured from materials whose electrical resistance varies as a function of external factors:

• Light Dependent Resistors (LDR): Their resistance changes based on the quantity of light affecting them.
• Temperature-Dependent Resistors (Thermistors): These electronic components vary their resistance based on temperature.
  • NTC Thermistors: Resistance decreases with increasing temperature (Negative Temperature Coefficient).
  • PTC Thermistors: Resistance increases with increasing temperature (Positive Temperature Coefficient).

Diodes: Semiconductor Operation

A Diode is a semiconductor device characterized by allowing the passage or circulation of electric current primarily in one direction (from anode to cathode).

In the forward direction (anode to cathode), the diode behaves like a closed switch with a low resistance value.

Relays: Automatic Switching

A Relay is an automatic switch composed of two distinct circuits: an electromagnetic circuit (coil) and a contact circuit.

The electromagnetic circuit operates with small amounts of current, activating a moving electromagnet. This electromagnet attracts the mobile contacts of the secondary circuit, allowing large amounts of current to flow.

A primary use of relays is control: small control signals can manage high power loads, effectively functioning as a switch or commutator.

Electrical Measurement: Multimeters

The Multimeter (often referred to by its function, such as Voltmeter) is the most common measuring device used in electricity. It allows measurement of voltage, current, and resistance, among other electrical magnitudes. It is suitable for both direct current (DC) and alternating current (AC).

There are two main types:

1. Analog Multimeters: Readings are taken via a needle moving across a graduated scale.
2. Digital Multimeters: Performs the same function but displays the measured value numerically on a screen.