# Types and applications of electronic circuits

Among the various applications of electronic circuits, we have some basic applications, which use electronic circuits on a daily basis. Next, we will have the presentation of what electronic circuits are, the classifications and examples of circuits, come on guys!

## What are electronic circuits?

We understand a circuit as a closed path, and the end is also the beginning. The electrical circuit is a closed circuit, with the connection of several elements, such as resistors, diodes, inductors, sources, transmission lines and switches, which allow the passage of electrical current.

Electronic circuits represent a type of electrical circuit, using a few more electronic components that perform transformations in electrical quantities , such as diodes and transistors.

Now imagine the light in your home, it is certainly connected to a source of electrical energy in an electrical circuit, and can be turned on or off. The electronic circuit allows you to go further, making the electric current-controlled, being able to perform several functions, from the simplest ones, such as decreasing or increasing the luminosity or performing the communication with satellites. This is what differentiates electrical circuits from electronic circuits.

Electrical circuit and electronic circuit, showing an element of difference between them.

In the electrical system, the lamp is directly connected to the power source, having no electronic equipment capable of controlling it. In the electronic system, the lamp is basically connected in a potentiometer, which in turn has the ability to regulate the intensity of the light, but in reality what controls the lamps is a dimmer, through an electronic circuit using semiconductors. .

## Classification of electronic circuits

Circuits can be classified according to several criteria, such as energy behaviour, manufacturing mechanisms and the type of voltage they are subjected to, whether continuous or alternating.

In the case of energetic behaviour, they can be:

• ASSETS: electronic circuits that generate energy, such as those of generators.
• LIABILITIES: electronic circuits that absorb energy, such as those of resistors (use energy in the form of heat), coils (store energy in the form of a magnetic field) and capacitors (concentrate energy in the form of an electric field).

Electronic circuits have numerous functions that they perform. We can highlight the rectifier circuits, which distinguish electrical signals according to frequency, which basically transform alternating current into direct current, for example. In addition, we can also cite as an example of the amplifier circuits, which increase the amplitude of a signal.

Along with the advancement of information technology, there was also the advancement of circuits identified as switchings, such as flip-flop and logic circuits. The continuous evolution of semiconductor materials has made it possible to manufacture components essential to circuits, so we can mention such electronic components: diodes, transistors and small modules made up of many electronic components.

The constant evolutions have brought improvements to citizenship, since the use of small modules is responsible for reducing the cost price and energy consumption, bringing even more speed and accuracy, in the case of electrical signals, which are transmitted and stored.

Nowadays it is possible to incorporate several transistors on minimal surfaces, allowing the processing of signals (with minimum amplitudes) in image reproduction, computers, communication and others. Among the types of electronic circuits, we highlight the rectifier electronic circuits and the amplifier electronic circuits that we will see below.

## Rectifier circuits

Rectifier electronic circuits are used to convert alternating current into direct current, being widely used in sources of devices connected directly to the outlet, and also in photovoltaic energy. The main part of the electronic rectifier circuit is the diode . A diode is an electronic component capable of allowing electric current to travel only in one direction.

To facilitate understanding, we can compare the diodes to a valve: the water will only flow in a single direction of the pipe, so that the diode has the same function, as we can see in the image below:

Diodes compared to the valve, which allow the current to flow in only one direction, thus varying according to the polarity, according to the valves: in the forbidden direction the valve is closed and in the permitted direction the valve is opened.

Next, we have a video from the Mundo da Elétrica channel, explaining in full detail what a diode is, in order to facilitate understanding in relation to the operation of the circuits that will be presented.

According to the characteristics of the diode, it is also used to rectify the alternating voltage of a circuit. The behavior of the ideal diode with direct polarization is like a closed switch, with a very low resistance, tending to zero and with reverse polarization it is like an open switch, with a very high resistance.

Electronic circuit full wave rectifier in bridge with capacitive filter and output signal

The image above represents a bridged full wave rectifier circuit. Analyzing the positive semicycle first, point A has a greater electrical potential in relation to the electrical potential of point B, thus the diodes D1 and D3 are correctly polarized, that is, they are conducting, while diodes D2 and D4 are polarized conversely, not driving. Thus, the current circulates from A to B, passing through the RL load, resulting only in a positive voltage in the load.

After analyzing the negative semicycle, the electrical potential at point B is greater than the electrical potential at point A, thus diodes D2 and D4 are directly polarized, while diodes D1 and D3 are inversely polarized. Thus, the current goes from B to A, passing through RL, resulting in negative voltages in the load only in the negative semicycles.

## Amplifier circuits

Another type of electronic circuit is the amplifier circuit, which is used in transmitters, digital equipment and radio and television receivers, for example. In general terms, the amplifier is equipment used to control a large amount of energy. The association between input and output of an amplifier operates according to the input frequency, where we have the transfer function, to the significance of the function we call the gain.

A simple example of an amplifier circuit is the speaker with microphone. In this circuit, a speaker with low impedance is used as a microphone, for which it is necessary to have pre-amplification of the signal. The circuit that will be presented can excite almost any amplifier.

Amplifier circuit (loudspeaker as microphone).

A PNP transistor is used to increase the signal impedance and intensity, allowing excitation of the preamplifier. The power is direct from a 9V battery, consuming a current of 2mA. As there are few components, the installation can be done in a small box.