Electronics

What is electronics?
Electronic components

What is electronics?

In an electrical circuit the current flows through the conductors and components naturally, having the current a value that depends on the components connected in the circuit.

In an electronic circuit, a control is exercised over the flow of the electric current.

But this is not new, just put a switch to let flow or not the current through a light bulb. (In this way, we would be “controlling” the flow of current through the bulb).

However, the most important difference lies in the “how” this current flow is controlled. In an electronics circuit, an electric current flow is controlled by another electrical signal, this being another electric current flow or a fixed voltage.

In other words:

In an electronic circuit … electricity is able to control electricity.

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Electronic components

Electronic components can be classified in:

Active components: usually can inject power into a circuit. They are made of semiconductors. E.g: Diodes, transistors.
Passive components: cannot introduce net energy into the circuit. E.g: Resistors, capacitors

For a circuit to be properly called “electronic circuit” it must contain at least one active element.

Passive components

Fixed resistors

They impede the flow of electric current
There is a colour code to know their value

Variable resistors

Potentiometer: A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.

Thermistor: semiconductor type of resistor whose resistance is strongly dependent on temperature. They can be
- Negative-temperature-coefficient (NTC): thermistors have less resistance at higher temperatures

- - Positive-temperature-coefficient (PTC): thermistors have more resistance at higher temperatures

Light Dependent Resistors (LDR): passive component that decreases resistance with respect to receiving luminosity on the component's sensitive surface

Capacitors

Device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other.

The property of a capacitor is the capacitance (C) that is defined as the amount of charge that can be stored at a given voltage. It is measured in Farads (F)

Electronic symbol

Active components

They are made up of semiconductor materials, whose properties allow to introduce "control" in the circuit.

Diodes

Devices that allow current to flow just in one direction.

The most known are LED's: Light Emitting Diode

Transistors

It is a semiconductor device used to amplify or switch electrical signals and power. It is composed of semiconductor material, usually with at least three terminals for connection to an electronic circuit. A voltage or current applied to one of the transistor's terminals (Base) controls the current through another pair of terminals (Collector and Emitter)

There are two main types of transistors depending on the sense of the controlled current: NPN and PNP

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