Types of Capacitors and Their Applications

In every electronic or electrical circuit, a capacitor plays a key role. So every day, the production of different types of capacitors can be done from thousands to millions. Each kind of capacitor includes its benefits, drawbacks, functions & applications. So, it is very important to know about each type of capacitor while selecting for any application. These capacitors range from small to large including different characteristics based on the type to make them unique. The small and weak capacitors can be found in radio circuits whereas the large capacitors are used in smoothing circuits. The designing of small capacitors can be done using ceramic materials by sealed with epoxy resin whereas the commercial purpose capacitors are designed with a metallic foil using thin Mylar sheets otherwise paraffin-impregnated paper.

Types of Capacitors and Its Uses

The capacitor is one of the most used components in electronic circuit design. It plays an important role in many of the embedded applications. It is available at different ratings. It consists of two metal plates separated by a non-conducting substance, or dielectric. It is often storage depots for analog signals and digital data.

The comparisons between the different types of capacitors are generally made with regards to the dielectric used between the plates. Some capacitors look like tubes, small capacitors are often constructed from ceramic materials and then dipped into an epoxy resin to seal them. So here are a few of the more common types of capacitors available. Let’s see them.

Dielectric Capacitor

Generally, these types of capacitors are the variable type that requires a continuous change in the capacitance for transmitters, receivers & transistor radios for tuning. Variable dielectric types are obtainable within multi-plate and air-spaced. These capacitors have a set of fixed as well as movable plates to move among the fixed plates.

The moving plate’s position as compared with the fixed plates will determine the approximate capacitance value. In general, the capacitance is maximum once the two sets of plates are completely connected. The tuning capacitor with high capacitance includes fairly large spacing otherwise air gaps among the two plates with breakdown voltages getting thousands of volts.

Mica Capacitor

The capacitor which uses Mica like the dielectric material is known as a mica capacitor. These capacitors are available in two types like clamped and silver. Clamped type is now considered outdated because of their lower characteristics but the silver type is used in its place.

These capacitors are fabricated by sandwiching metal coated mica sheets on both faces. After that, this design is enclosed in epoxy for protecting it from the surroundings. Generally, these capacitors are used whenever stable capacitors with relatively small values are required.

The minerals of Mica are extremely constant chemically, mechanically & electrically due to its precise crystalline structure which includes typical layers. So the manufacturing of thin sheets with 0.025 to 0.125 mm is possible.

The most frequently used mica is phlogopite & muscovite. In that, muscovite has good electrical properties, whereas the second has a high-temperature resistance. Mica is investigated in India, South America & Central Africa. The high difference in the composition of raw material leads to the high cost required for examination and categorization. Mica doesn’t act in response to acids, water & oil solvents.
Please refer to this link to know more about Mica Capacitor

Polarized Capacitor

The capacitor that has specific polarities like positive and negative is called a polarized capacitor. Whenever these capacitors are used in the circuits we have to check that they are allied within ideal polarities. These capacitors are classified into two type’s namely electrolytic and supercapacitors.

Film Capacitors

Film Capacitors are the most normally ready of numerous types of capacitors, comprising of a generally expansive group of capacitors with the distinction being in their dielectric properties. They are available in almost any value and voltages as high as 1500 volts. They come in any tolerance from 10% to 0.01%. Film capacitors additionally arrive in a combination of shapes and case styles.

There are two types of film capacitors, radial lead type, and axial lead type. The electrodes of film capacitors may be metalized aluminum or zinc, applied on one or both sides of the plastic film, resulting in metalized film capacitors called film capacitors. The film capacitor is shown in the figure below:

Film Capacitors are sometimes called plastic capacitors because they use polystyrene, polycarbonate, or Teflon as their dielectrics. These film sorts need a much thicker dielectric film to lessen the danger of tears or puncture in the film and is, therefore, more suited to lower capacitance values and bigger case sizes.

The film capacitors are physically larger and more expensive, they are not polarized, so they can be used in AC voltage applications, and they have much more stable electrical parameters. Dependence of capacitance and dissipation factor, can be applied in frequency-stable Class 1 applications, replacing Class 1 ceramic capacitors.

Ceramic Capacitors

Ceramic capacitors are used in high-frequency circuits such as audio to RF. They are also the best choice for high-frequency compensation in audio circuits. These capacitors are also called disc capacitors. Ceramic capacitors are made by coating two sides of small porcelain or ceramic disc with silver and are then stacked together to make a capacitor. One can make both low capacitance and high capacitance in ceramic capacitors by changing the thickness of the ceramic disc used. The ceramic capacitor is shown in the figure below:

They come in values from a few Pico farads to 1 microfarad. The voltage range is from a few volts up to many thousands of volts. Ceramics are inexpensive to manufacture and they come in several dielectric types. The tolerance of ceramics is not great but for their intended role in life, they work just fine.

Electrolytic Capacitors

These are the most prevalently used capacitors that have a wide tolerance capacity. Electrolytic capacitors are available with working voltages up to about 500V, although the highest capacitance values are not available at high voltage and higher temperature units are available, but uncommon. There are two types of electrolytic capacitors, tantalum, and aluminum in common.

Tantalums capacitors have an ordinarily better exhibition, higher value, and are ready just to a more limited extent of parameters. The dielectric properties of tantalum oxide are much superior to those of aluminum oxide giving an easier leakage current and better capacitance strength which makes them suitable for obstructing, decoupling, filtering applications.

The thickness of the aluminum oxide film and heightened breakdown voltage gives the capacitors exceptionally elevated capacitance values for their size. In a capacitor, the foil plates are anodized by a dc current thus setting the extremity of plat material and confirming the polarity of its side.

The tantalum and aluminum capacitors are shown in the figure below:

Electrolytic capacitors are classified into two types

• Aluminium Electrolytic Capacitors
• Tantalum Electrolytic Capacitors
• Niobium Electrolytic Capacitors

Please refer to this link to know more about Electrolytic capacitors

Super Capacitors

The capacitors which have an electrochemical capacity with high capacitance values as compared with other capacitors are known as supercapacitors. The categorization of these can be done like a group that lies among electrolytic capacitors as well as rechargeable batteries which are known as ultracapacitors.

There are several benefits by using these capacitors like the following,

• The capacitance value of this capacitor is high
• The charge can be stored as well as delivered very quickly
• These capacitors can handle additional charge with discharge cycles.
• The applications of supercapacitors include the following.
• These capacitors are utilized in buses, cars, trains, cranes & elevators.
• These are used in regenerative braking & for memory backup.
• These capacitors are available in different types like Double-layered, Pseudo & Hybrid ones.

Non-Polarized Capacitor

The capacitors don’t have polarities like positive otherwise negative. The electrodes of non-polarized capacitors can be inserted randomly into the circuit for feedback, coupling, decoupling, oscillation & compensation. These capacitors have small capacitance so used in pure AC circuits & also used in high-frequency filtering. The selection of these capacitors can be done very conveniently with similar models & specifications. The nonpolarized capacitor types are

Ceramic Capacitors

Please refer to this link to know more about ceramic capacitors

Silver Mica Capacitors

Please refer to this link to know more about mica capacitors

Polyester Capacitors

Polyester or Mylar capacitor is cheap, precise & has small leakage. These capacitors work in the range of 0.001 to 50 microfarad. These capacitors are applicable where stability and accuracy are not so significant.

Polystyrene Capacitors

These capacitors are extremely accurate includes less leakage. These are utilized within filters and also wherever accuracy, as well as stability, is significant. These are quite costly & work in the range of 10 pF to 1 mF.

Polycarbonate Capacitors

These capacitors are costly & available extremely in good quality, with high accuracy and very low leakage. Unfortunately, they have been discontinued and are now hard to find. They perform well in harsh and high-temperature environments in the 100 pF to 20 mF range.

Polypropylene Capacitors

These capacitors are costly and the range of its performance can be in the 100 pF to 50 mF. These are extremely constant, accurate over time & have very little leakage.

Teflon Capacitors

These capacitors are the most stable, accurate & have nearly no leakage. These are considered the best capacitors. The way of behavior is precisely similar over a broad range of frequency variations. They function in the range of 100 pF to 1 mF.

Glass Capacitors

These capacitors are very strong, stable, and operates in the range of 10 pF to 1,000 pF. But, these are also very expensive components.

Polymer Capacitor

A polymer capacitor is an electrolytic capacitor (e-cap) that uses a solid electrolyte of a conductive polymer like the electrolyte instead of gel or liquid electrolytes.

The electrolyte drying can be easily avoided with the help of a solid electrolyte. This kind of drying is one of the features that stop the life span of normal electrolytic capacitors. These capacitors are classified into different types like Polymer Tantalum-e-cap, Polymer Aluminum-e-cap, Hybrid polymer Al-e-cap & Polymer niobium.

In most of the applications, these capacitors have used an alternative to electrolytic capacitors, only if the highest rated voltage is not increased. The solid polymer type capacitors highest rated voltage is lesser as compared with the highest voltage of classical electrolytic type capacitors like up to 35 volts, even though some polymer type capacitors are designed with highest operating voltages like 100 volts DC.

These capacitors have different and better qualities as compared with a longer lifetime, working temperature is high, good stability, lower ESR (equivalent series resistance) & failure mode is much safer.

Leaded & Surface Mount Capacitors

Capacitors are accessible like leaded ranges & surface mount capacitors. Almost all kinds of the capacitor are obtainable like leaded versions such as ceramic, electrolytic, supercapacitors, silver mica, plastic film, glass, etc. The surface mount or SMD is limited but they must resist the temperatures which are used within the process of soldering.

When the capacitor doesn’t have any leads & also as a result of the soldering method is used, then SMD capacitors are exposed to the complete temperature rise of the solder itself. As a result, not all varieties are available as SMD capacitors.

The main surface mount capacitor types include ceramic, tantalum, and electrolytic. All of these have been developed to withstand the very high temperatures of soldering.

Special Purpose Capacitors

Special purpose capacitors are utilized in AC power applications such as UPS & CVT systems up to 660V AC. The selection of appropriate capacitors mainly plays an important role within the life expectancy of the capacitors. Therefore, it is completely required to utilize proper capacitor value through a voltage-current rating to match the precise application. The features of these capacitors are sturdiness, durability, shockproof, dimensional accuracy, and extremely strong.

Types of Capacitors in AC Circuits

When the capacitors are used in AC circuits then capacitors act differently as compared with resistors, as resistors permit electrons to flow throughout them which is directly proportional toward the voltage drop, whereas the capacitors resist changes within voltage through supplying or drawing current because they charge otherwise discharge toward the new voltage level.

Capacitors turn into charged toward the applied voltage value which acts as a storage device to maintain the charge till the supply voltage is there throughout the DC connection. A charging current will supply into the capacitor to oppose any modifications toward the voltage.

For instance, consider a circuit that is designed with a capacitor as well as an AC power source. So, there is a phase difference of 90 degrees among the voltage and the current with the current achieving its peak 90 degrees before the voltage achieves its peak.

The AC power supply generates an oscillating voltage. When the capacitance is high then the huge supply must flow to build up a specific voltage over the plates & the current will be higher.
The voltage frequency is higher, and then the available time is shorter to adjust the voltage, so the current will be high when the frequency and the capacitance are increased.

Variable Capacitors

A Variable Capacitor is one whose capacitance may be intentionally and repeatedly changed mechanically. This type of capacitor is utilized to set the frequency of resonance in LC circuits, for instance, to adjust the radio for impedance matching in antenna tuner devices.

Applications of Capacitors

Capacitors have applications in both electrical and electronics. They are used in filter applications, energy storage systems, motor starters, and signal processing devices.

How to Know the Value of Capacitors?

Capacitors are the essential components of an electronic circuit without which the circuit cannot be completed. The use of capacitors includes smoothing the ripples from AC in power supply, coupling and decoupling the signals, as buffers, etc. Different types of capacitors like Electrolytic capacitor, Disc capacitor, Tantalum capacitor, etc are used in circuits. Electrolytic capacitors have the value printed on its body so that its pins can be easily identified.

Usually, the large pin is positive. The black band present near the negative terminal indicates the polarity. But in Disc capacitors, only a number is printed on its body so it is very difficult to determine its value in PF, KPF, uF, n, etc. For some capacitors, the value is printed in terms of uF, while in others an EIA code is used.  104. Let us see the methods to identify the capacitor and to calculate its value.

The number on the capacitor represents the capacitance value in Pico Farads. For example, 8 =  8PF

If the third number is zero, then the value is in P e.g. 100 = 100PF

For a 3 digit number, the third number represents the number of zeros after the second digit, For example,  104 = 10 – 0000 PF

If the value is obtained in PF, it is easy to convert it into KPF or uF

PF / 1000 = KPF or n, PF / 10, 00000 = uF. For a capacitance value of 104 or 100000 in pF, it is 100KpF or n or 0.1uF.

Conversion Formula

n x 1000 = PF PF/1000 = n PF/1,000,000 = uF uF x 1,000,000 = PF uF x 1,000,000/1000 = n n=1/1,000,000,000F uF = 1/ 1000,000 F

The letter below the capacitance value determines the tolerance value.

473 = 473 K

For a 4 digit number, if the 4^th digit is a zero, then the capacitance value is in pF.

E.g. 1500 = 1500PF

If the number is just a floating-point decimal number, the capacitance value is in uF.

E.g. 0.1 = 0.1 uF

If an alphabet is given below the digits, it represents a decimal and the value is in KPF or n

E.g. 2K2 = 2.2 KPF

If the values are given with slashes, the first digit represents value in UF, second its tolerance, and third its maximum voltage rating

E.g. 0.1/5/800 = 0.01 uF / 5 % / 800 Volt.

Some Common Disc Capacitors are

Without a Capacitor, the circuit design will not be complete since it has an active role in the functioning of a circuit. The Capacitor has two electrode plates inside separated by a dielectric material such as paper, mica, etc. What happens when the electrodes of the capacitor are connected to a power supply? The capacitor charges to its full voltage and retains the charge. The capacitor has the ability to store current which is measured in terms of Farads.

The capacitance of a capacitor depends on the area of its electrode plates and the distance between them. Disc capacitors do not have polarity so that they can be connected either way round. Disc capacitors are mainly used for coupling / decoupling the signals. The Electrolytic capacitors, on the other hand, have polarity so that if the polarity of the capacitor changes, it will explode. Electrolytic capacitors are mainly used as filters, buffers, etc.

Each capacitor has its own capacitance which is expressed as the Charge in the capacitor divided by the Voltage. Thus Q/V. When you use a capacitor in a circuit, some important parameters should be considered. First is its Value. Select a proper value, either low or high value depending on the circuit design.

The value is printed on the body of most of the capacitors in uF or as EIA code. In Color-coded capacitors, the values are represented as color bands, and by using a capacitor color code chart; it is easy to identify the capacitor. Below is the Color chart to identify a color-coded capacitor.

See, like resistors, each band on the capacitor has a value. The value of the First band is the first number in the color chart. Similarly, the value of the Second band is the Second number in the color chart. The third band is the multiplier as in the case of a resistor. The fourth band is the Tolerance of the capacitor. The Fifth band is the body of the capacitor which represents the Working voltage of the capacitor. The Red color represents 250 volts and Yellow represents 400 volts.

Tolerance and Working voltage are two important factors to be considered. No capacitor has the rated capacitance and it may vary.

So use a good quality capacitor like a Tantalum capacitor in sensitive circuits like oscillator circuits. If the Capacitor is used in AC circuits, it should have a working voltage of 400 volts. The working voltage of the electrolytic capacitor is printed on its body. Select a capacitor with a working voltage three times higher than the power supply voltage.

For example, if the power supply is 12 volts, use a 25 volt or 40-volt Capacitor. For smoothing purposes, it is better to take a high-value capacitor like 1000 uF to remove the ripples of AC almost completely. In the power supply of Audio circuits, it is better to use a 2200 uF or 4700 uF capacitor since the ripples may create hum in the circuit.

Leakage current is another problem in capacitors. Some of the charges will leak, even if the capacitor is charging. This is a verse in Timer circuits since the timing cycle depends on the charge/discharge time of the capacitor. Low leakage Tantalum capacitors are available and use them in Timer circuits.

Understanding the Reset Capacitor Function in Microcontroller

A Reset is used to start-up or to restart the AT80C51 microcontroller functionality. A reset pin follows two conditions to startup the microcontroller. They are

1. The power supply must be in the specified range.
2. The reset pulse width duration must be at least two machine cycles.

The reset must be kept active until all two of the conditions are respected.

In this type of circuit, the capacitor and resistor arrangement from the supply is connected to reset pin no. 9. While the supply switch is ON, the capacitor starts charging. At this time, the capacitor acts like a short circuit in the beginning. When the reset pin is set to HIGH, the microcontroller goes to the power-on state and after some time the charging stops.

When charging stops, the reset pin goes to the ground because of the resistor. The reset pin should go too high then go too low, then the program starts from begging. If this arrangement does not have the reset capacitor or would have been left unconnected, the program starts from anywhere on the microcontroller.

Thus, this is all about an overview of different types of capacitors and their applications. Now you have got an idea about the concept of the types of capacitors and their applications if you have queries on this topic or on the electrical and electronic projects leave the comments below.

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Ceramic Capacitors by made-in-china