Capacitor and Types of Capacitor

Capacitors are components widely used in electronics and electricity to do different jobs and projects with them, hence the importance of knowing how they are. constituted and what each of their types are like.

What is an electrical capacitor?

A component formed by two conductive metal surfaces called armatures.dielectric that are separated by an insulating medium called

What is the dielectric constant of a capacitor?

The result of dividing the value of the capacity of a capacitor with a given dielectric and the capacity that the capacitor would have is known as Dielectric constant. same capacitor if instead of said dielectric air were placed. Air is taken as a standard, and its dielectric constant is considered to be one.

What is the capacitance inside a capacitor?

The Capacitance is the apparent resistance offered by the capacitors when the capacitors are allowed to circulate through them. alternating currents.

Capacity of a capacitor

The Capacity of a capacitor is the relationship that exists between the amount of electricity stored and the voltage applied to its terminals. That is, dividing the stored charge by the applied voltage, we will have the capacity of the capacitor. The capacity depends on the surface of the reinforcement and the thickness of the dielectric.

The formula to know the capacity of a capacitor is:

F (farads) = Q (coulombs))/(V (volts))

Being F is the consonant used to express the unit of capacity of an Electric Capacitor: The Farad , which is defined as the capacity of a conductor that, when applying a potential of one volt, acquires the charge of a coulomb. Since it is extremely large, a submultiple called microfarad is used, which is a million times smaller. There are also submultiples of the microfarad, which are: the nanofarad, which is a thousand times smaller than it, and the picofarad, which is a million times smaller. These units are briefly written: F, mF, nF, and pF, respectively.

Types of Capacitors

There are many different types of capacitors and each varies in its characteristics and each has its own advantages and disadvantages.

Some types of capacitors can be charged to higher voltages and can therefore be used in high voltage applications. Some capacitors can charge up to very high charges, such as aluminum electrolytic capacitors. Some capacitors have very low leak rates and others have very high leak rates. All of these factors determine how and in what application each of the capacitors will be used in the circuits.

Below is a list of the different types of capacitors, as we review the characteristics that make them up:

Aluminum Electrolytic Capacitors

Aluminum capacitors are capacitors that are made up of two rolled strips of aluminum foil with a strip of absorbent paper between them that is soaked in an electrolyte solution, all of this is sealed in a can.

Aluminum electrolytic capacitors cover the capacitance range from 0.1μF to 500,000μF, making them one of the largest capacitors in terms of storage capacity. This is one of their main advantages, they store a high charge value. Working voltages vary from 10V to 100V. The disadvantages of aluminum electrolytic capacitors are that they have high leakage rates, so they tend to leak a lot of DC current, making them poor in high frequency AC coupling applications. They also have a wide tolerance range, usually ±20% or more. This makes them poor in applications where precise values ​​are needed, such as timing or filtering circuits. Therefore, they are generally not used in these applications.

Tantalum Capacitors

Tantalum capacitors, like aluminum, are electrolytic capacitors, meaning they are polarized. Their main advantages (especially over aluminum capacitors) are that they are smaller, lighter and more stable. They have lower leakage rates and less inductance between the cables. However, their disadvantages are that they have a lower maximum storage capacitance and a lower maximum working voltage.  For the latter reason, tantalum capacitors are mainly used in analog signal systems that lack high current noise.

Ceramic Capacitors

Ceramic capacitors have high capacitance values ​​for their size. They are manufactured in the range of 1pF up to several microfarads (μF), but do not have the very high capacitance values ​​like electrolytic capacitors. They are manufactured with a wide range of working voltages and tolerance values. A main advantage of ceramic capacitors is that internally they are not constructed as a coil, so they have low inductance and are therefore well suited for higher frequency applications. They are widely used for many purposes, including decoupling.

An NPO ceramic capacitor is one that is an ultra-stable capacitor or temperature compensator. It is one of the most stable capacitors. It has very predictable temperature coefficients (TC) and generally does not age over time. As such, it is very suitable for tuning circuits and filter applications.

Polyester Capacitors

Polyester capacitors are capacitors composed of metal plates with polyester film between them, or a metallized film is deposited on the insulator.

Polyester capacitors are available in the range of 1nF to 15μF, and with working voltages of 50V to 1500V. They come with tolerance ranges of 5%, 10% and 20%. They have a high temperature coefficient. They have a high insulation resistance, making them good capacitors of choice for coupling and/or storage applications. Compared to most other types, polyester capacitors have a large capacity per unit volume. This means that more capacitance can fit into a physically smaller capacitor. This feature, together with its relatively low price, makes polyester capacitors a widely used, popular and cheap capacitor.

Polypropylene Capacitors

Polypropylene capacitors are capacitors that have a dielectric that is made of polypropylene film.

Polypropylene capacitors cover the value range from 100pF to 10μF. One of its main characteristics is its high working voltage. Types of polypropylene are manufactured with working voltages of up to 3000V. These characteristics make polypropylene capacitors useful in circuits in which operating voltages are typically high. These include power supply circuits, power amplifiers, particularly tube amplifiers, and TV circuits. Another great advantage of polypropylene capacitors is their excellent tolerance values. The tolerance is about 1%, so it’s pretty precisely close to its nominal values. Polypropylene capacitors are used when better tolerance is needed than a polyester capacitor can provide. Polypropylene capacitors also have high insulation resistance, making them a good choice for coupling and/or storage applications. They exhibit stable capacitance for frequencies below 100KHz.

These capacitors are used for noise suppression, blocking, bypassing, coupling, filtering, timing and pulse handling.

Polystyrene Capacitors

Polystyrene capacitors are capacitors that have a dielectric composed of polystyrene.

They come only in low values, usually 10pF to 47nF. Typically, their tolerance is 5% to 10%, but high precision polystyrene capacitors are also available with tolerances of 1% and 2%. Working voltages for polystyrene capacitors are 30V to 630V. Polystyrene capacitors are advantageous because they have a high insulation resistance, making them good for use in coupling and storage applications. Precision types are suitable for timing, adjustment and filter circuits.

One of their disadvantages is that they are built as a coil inside, so they are not suitable for high frequency applications. (This is because coils create inductance, and inductance blocks high-frequency signals from passing through.) Another disadvantage is that polystyrene capacitors exhibit a permanent change in value if they are ever exposed to temperatures much above 70° C; They do not return to their previous value when cooling.

Polycarbonate Capacitors

Polycarbonate capacitors are capacitors that have a polycarbonate dielectric.

They come in the capacitance value range of 100pF to 10μF and have working voltages up to 400V DC. They are advantageous in the area that they have fairly good temperature coefficients, so they do not vary much with changes in temperature. This makes them preferred over polyester capacitors. They are disadvantageous because they have quite high tolerance levels, 5% and 10%, which makes them not so good for high precision applications.

Silver Mica Capacitors

Silver mica capacitors are capacitors that are made by depositing a thin layer of silver on a mica dielectric.

Mica silver capacitors are very stable over time. They are advantageous because they have tolerances of 1 percent or less. They also have a good temperature coefficient and excellent resistance. However, they do not have high capacitance values ​​and can be expensive.

Mica silver capacitors are used in resonance circuits and high-frequency filters, due to good temperature stability. They are also used in high voltage circuits, due to their good insulation.

Paper Capacitor

Paper capacitors are capacitors that are made of thin flat strips of metal foil conductors separated by a wax paper dielectric.

They have a capacitance range of 500pF to 50μF and a high working voltage; Therefore, they are mainly used in high-voltage equipment.

The disadvantage of paper capacitors is that they have high leakage rates, making them unsuitable for AC coupling, and their tolerances are no better than 10% to 20%, making them unsuitable for precision timing circuits. .