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Any electronic device is made up of a series of components connected to each other which can be classified into two groups according to their operation:

• Active components. They can control the current flow of a circuit or realize some gain. Semiconductors are a clear case of active components.
• Passive components. They are basically interconnect components. They transmit or modify the level of a signal.

Passive components have always been used in electricity while active components arose with the valves that were part of the first televisions and radios. The tubes were giving way to the semiconductors that, as everyone knows, are the basis of the integrated circuits that are part of any current electronic device.

A complex integrated circuit is a microprocessor. A microprocessor is made up of millions of transistors and is manufactured in special rooms free of dust and suspended particles using complex techniques such as photolithography.

Next, the most common passive and active components will be studied in depth.

Passive components.

The following sections will explain in depth the characteristics of the passive components that are part of any electronic device.

Resistance

Resistors consume power in an electronic circuit and to fulfill their function they are manufactured with different materials such as carbon, glass, etc.

The nominal value of the resistors is the Ohm, which owes its name to the German physicist Georg Simon Ohm and is represented by the Greek letter omega Ω.

As can be supposed, depending on the material used in its manufacture, its resistivity will be different. It also has a lot to do with how long it is and how thick it is.

The resistors are marked with colored bands on the body of the resistor. If the resistance is very small, it is not marked with these colored bands.

The condenser

Capacitors may be the most common electronic components in any circuit. Its function is to store energy.

They are made up of two layers of metal separated by an insulating or dielectric material.

As the capacitor has two terminals or legs, each of them will be connected to a previously mentioned metal sheet.

There are many types of capacitors (mkp, ceramic, electrolytic, lentil, paper, etc.). In the previous figure you can see some of them.

The capacity of a capacitor is measured in farads, it is represented by the letter F.

The transformer

Many times we call many devices that in electronics not only contain a transformer but many other components as a transformer.

In electronics a transformer allows to decrease or increase the voltage in a circuit. The basis of the transformer is a physical phenomenon called induction.

What is induction?
In an iron core, as can be seen in the previous figure, two cables are wound, one primary connected to the current input and the other secondary. The primary that is fed by the current causes a physical induction effect on the second, generating current in the latter.
Depending on the number of turns that the primary and secondary have, the transformer can increase the voltage or decrease the voltage of the circuit.

Given this, when we call a power supply, laptop charger, etc. a transformer. Actually we are calling a transformer a series of electronic devices in addition to the transformer itself.

The fuse

Fuses are a protection element. They are generally made up of a very thin metal wire through which the current passes. This metal is prepared in such a way that when more current than allowed passes, the metal wire, which is very thin, melts due to the heat generated.

Depending on the thickness of the metal, it will allow more or less current to pass and in this way the circuit is protected against excess current that could damage other components.

When a fuse breaks or melts, it is replaced by another with the same characteristics and that resists the same amperes of current.

This protection element can be found in many electrical and electronic circuits such as power supplies for example.

Active components.

Active components were those that could control the current flow of a circuit or realize some gain. Microprocessors and electronic circuits are clearly active components, but there are other very common ones that will be described below:

The battery

The purpose of batteries is to transform chemical energy into electrical energy.

Depending on their composition, there are rechargeable and non-rechargeable batteries. In all of them there are two poles or electrodes, one is positive (cathode) and the other is negative (anode).

The negative pole is more negatively charged than the positive pole and when both are joined through a conductor (for example a cable), the electrons from the negative pole will pass to the positive pole, thus producing an electric current.

In computers, whether they are laptops or desktops, batteries can be found, such as the battery that feeds the CMOS memory responsible for storing the BIOS values ​​(its function will be studied in depth in the next chapter).

The transistor

By number, it is the most widely used electronic component since current microprocessors have millions of them and they can also be found in RAM memories and practically in most integrated circuits.

All the appliances and household appliances of daily life (microwaves, cleaning robots, smartphones, X-ray machines, televisions, ultrasound machines, dishwashers, washing machines, etc.) contain transistors inside.

Did you know…
A Core i9 Skylake transistor has 2.6 billion transistors.

The diode

Diodes are made of semiconductors such as silicon or germanium and are active components. Its function within an electronic circuit is to allow the flow of current only in one direction.

The most common in everyday life are LED diodes (Light Emitting Diode) which are diodes that emit light.

Did you know…
There are diodes that emit ultraviolet or infrared light.

LEDs have been used for a long time in electronic equipment (hard drive, power, battery indicators, etc.) and currently in light bulbs and lights of all kinds.

Integrated circuits

Integrated circuits are the basis of modern electronics. They are formed by a thin sheet of silicon in which transistors, resistors, capacitors, circuits, etc. are created by means of the photolithography technique. Basically, the active and passive components that have been studied in previous sections will be created.

Remember
Formerly, with lithography, a relief drawing was drawn on a stone or a plate and with ink it was reproduced as many times as desired.

The microprocessor

A microprocessor is the most complex printed circuit. It will be made up of millions of transistors and its logic is extremely complex. If moved to the world of people, the microprocessor would be the brain.

There are microprocessors in many devices such as vehicles, elevators, smartphones, drones, robots, etc.