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Electronics Tutorial about various Types of Capacitor available and the Capacitor Types including electrolytic, ceramic, tantalum, and plastic film. 3 Capacitor Types. As mentioned already, there is a wide range of different capacitors. The capacitors briefly introduced in Chapter , which play the most . Capacitors are manufactured in many forms, styles, lengths, girths, and from many materials. "Rubycon, Aluminum Electrolytic Capacitors for Strobe Flash " (PDF). ^ "Electrolytic Capacitors - FTCAP GmbH". aracer.mobi ^ Jump up to: B. E.

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Types Of Capacitors Pdf

All rights reserved. No Current flows through a capacitor except for undesired leakage current. . Two common types of electrolytic capacitors are Aluminum and. Types of Capacitors. There are all sorts of capacitor types. When deciding which to use, there are several factors to consider: ○ Size. ○ Maximum voltage. Capacitor Construction, Parameters and Properties. .. While capacitors are one type of component, there are many types of capacitors that are differentiated by.

Ceramic Capacitor Electrolytic Capacitor Generally, the electrolyte capacitors are used when the large capacitor values are required. The thin metal film layer is used for one electrode and for the second electrode cathode a semi-liquid electrolyte solution which is in jelly or paste is used. The dielectric plate is a thin layer of oxide, it is developed electrochemically in production with the thickness of the film and it is less than the ten microns. Electrolytic Capacitor This insulating layer is very thin, it is possible to make capacitors with a large value of capacitance for a physical size, which is in small and the distance between the two plates is very small. The types of capacitors in the majority of electrolytic are polarized, which is DC voltage is applied to the capacitor terminal and they must be correct polarity. If the positive to the positive terminal and the negative to the negative terminal as an incorrect polarization will break the insulating oxide layer and there will be permanent damage.

All properties can be defined and specified by a series equivalent circuit composed out of an idealized capacitance and additional electrical components which model all losses and inductive parameters of a capacitor.

In this series-equivalent circuit the electrical characteristics are defined by:.

The rated capacitance C R or nominal capacitance C N is the value for which the capacitor has been designed. Actual capacitance depends on the measured frequency and ambient temperature. According to the number of values per decade, these were called the E3, E6, E12, E24 etc. Millifarad and kilofarad are uncommon. The percentage of allowed deviation from the rated value is called tolerance. The actual capacitance value should be within its tolerance limits, or it is out of specification.

The required tolerance is determined by the particular application. The narrow tolerances of E24 to E96 are used for high-quality circuits such as precision oscillators and timers. General applications such as non-critical filtering or coupling circuits employ E12 or E6. Capacitance typically varies with temperature. The different dielectrics express great differences in temperature sensitivity.

Most discrete capacitor types have more or less capacitance changes with increasing frequencies. The dielectric strength of class 2 ceramic and plastic film diminishes with rising frequency. Therefore, their capacitance value decreases with increasing frequency. This phenomenon for ceramic class 2 and plastic film dielectrics is related to dielectric relaxation in which the time constant of the electrical dipoles is the reason for the frequency dependence of permittivity.

The graphs below show typical frequency behavior of the capacitance for ceramic and film capacitors. Frequency dependence of capacitance for ceramic class 2 capacitors NP0 class 1 for comparisation. For electrolytic capacitors with non-solid electrolyte, mechanical motion of the ions occurs.

Their movability is limited so that at higher frequencies not all areas of the roughened anode structure are covered with charge-carrying ions. As higher the anode structure is roughened as more the capacitance value decreases with increasing frequency. Capacitance may also change with applied voltage. This effect is more prevalent in class 2 ceramic capacitors. The permittivity of ferroelectric class 2 material depends on the applied voltage.

Higher applied voltage lowers permittivity. This behavior is a small source of non-linearity in low-distortion filters and other analog applications.

In audio applications this can cause distortion measured using THD. Simplified diagram of the change in capacitance as a function of the applied voltage for V capacitors in different kind of ceramic grades. Simplified diagram of the change in capacitance as a function of applied voltage for X7R ceramics with different rated voltages.

The voltage at which the dielectric becomes conductive is called the breakdown voltage, and is given by the product of the dielectric strength and the separation between the electrodes. The dielectric strength depends on temperature, frequency, shape of the electrodes, etc.

Because a breakdown in a capacitor normally is a short circuit and destroys the component, the operating voltage is lower than the breakdown voltage. The operating voltage is specified such that the voltage may be applied continuously throughout the life of the capacitor. The rated voltage UR is the maximum DC voltage or peak pulse voltage that may be applied continuously at any temperature within the rated temperature range.

The voltage proof of nearly all capacitors decreases with increasing temperature. Some applications require a higher temperature range. Lowering the voltage applied at a higher temperature maintains safety margins. For some capacitor types therefore the IEC standard specify a second "temperature derated voltage" for a higher temperature range, the "category voltage". The category voltage UC is the maximum DC voltage or peak pulse voltage that may be applied continuously to a capacitor at any temperature within the category temperature range.

In general, a capacitor is seen as a storage component for electric energy. But this is only one capacitor function. A capacitor can also act as an AC resistor. In many cases the capacitor is used as a decoupling capacitor to filter or bypass undesired biased AC frequencies to the ground. Other applications use capacitors for capacitive coupling of AC signals; the dielectric is used only for blocking DC.

For such applications the AC resistance is as important as the capacitance value. Impedance extends the concept of resistance to AC circuits and possesses both magnitude and phase at a particular frequency.

This is unlike resistance, which has only magnitude. In capacitor data sheets, only the impedance magnitude Z is specified, and simply written as "Z" so that the formula for the impedance can be written in Cartesian form. In the special case of resonance , in which the both reactive resistances. The impedance specified in the datasheets often show typical curves for the different capacitance values. With increasing frequency as the impedance decreases down to a minimum.

The lower the impedance, the more easily alternating currents can be passed through the capacitor. At the apex , the point of resonance, where XC has the same value than XL, the capacitor has the lowest impedance value.

Here only the ESR determines the impedance. With frequencies above the resonance the impedance increases again due to the ESL of the capacitor. The capacitor becomes an inductance. As shown in the graph, the higher capacitance values can fit the lower frequencies better while the lower capacitance values can fit better the higher frequencies.

This is the reason for using electrolytic capacitors in standard or switched-mode power supplies behind the rectifier for smoothing application.

They also have significantly lower parasitic inductance, making them suitable for higher frequency applications, due to their construction with end-surface contacting of the electrodes. To increase the range of frequencies, often an electrolytic capacitor is connected in parallel with a ceramic or film capacitor.

Many new developments are targeted at reducing parasitic inductance ESL. This increases the resonance frequency of the capacitor and, for example, can follow the constantly increasing switching speed of digital circuits.

Parasitic inductance is further lowered by placing the electrodes on the longitudinal side of the chip instead of the lateral side. The "face-down" construction associated with multi-anode technology in tantalum electrolytic capacitors further reduced ESL.

Capacitor families such as the so-called MOS capacitor or silicon capacitors offer solutions when capacitors at frequencies up to the GHz range are needed. ESL in industrial capacitors is mainly caused by the leads and internal connections used to connect the capacitor plates to the outside world. Large capacitors tend to have higher ESL than small ones because the distances to the plate are longer and every mm counts as an inductance. For any discrete capacitor, there is a frequency above DC at which it ceases to behave as a pure capacitor.

The self-resonant frequency is the lowest frequency at which the impedance passes through a minimum. For any AC application the self-resonant frequency is the highest frequency at which capacitors can be used as a capacitive component. This is critically important for decoupling high-speed logic circuits from the power supply. The decoupling capacitor supplies transient current to the chip. Without decouplers, the IC demands current faster than the connection to the power supply can supply it, as parts of the circuit rapidly switch on and off.

To counter this potential problem, circuits frequently use multiple bypass capacitors—small nF or less capacitors rated for high frequencies, a large electrolytic capacitor rated for lower frequencies and occasionally, an intermediate value capacitor.

The summarized losses in discrete capacitors are ohmic AC losses. DC losses are specified as " leakage current " or "insulating resistance" and are negligible for an AC specification. AC losses are non-linear, possibly depending on frequency, temperature, age or humidity. The losses result from two physical conditions:. The largest share of these losses in larger capacitors is usually the frequency dependent ohmic dielectric losses.

For smaller components, especially for wet electrolytic capacitors, conductivity of liquid electrolytes may exceed dielectric losses. To measure these losses, the measurement frequency must be set.

IEC states that ohmic losses should be measured at the same frequency used to measure capacitance. These are:. ESR can be shown as an ohmic part in the above vector diagram. ESR values are specified in datasheets per individual type. These capacitors have smaller losses than electrolytic capacitors and mostly are used at higher frequencies up to some hundred MHz. However the numeric value of the dissipation factor, measured at the same frequency, is independent on the capacitance value and can be specified for a capacitor series with a range of capacitance.

Capacitors with very low losses, such as ceramic Class 1 and Class 2 capacitors, specify resistive losses with a quality factor Q. Ceramic Class 1 capacitors are especially suitable for LC resonant circuits with frequencies up to the GHz range, and precise high and low pass filters. Q is defined as the reciprocal value of the dissipation factor. Every AC current flow through a capacitor generates heat inside the capacitor body. The internal generated heat has to be distributed to the ambient.

The temperature of the capacitor, which is established on the balance between heat produced and distributed, shall not exceed the capacitors maximum specified temperature. Hence, the ESR or dissipation factor is a mark for the maximum power AC load, ripple current, pulse load, etc.

Ripple and AC currents mainly warms the capacitor body. By this currents internal generated temperature influences the breakdown voltage of the dielectric.

Higher temperature lower the voltage proof of all capacitors. In wet electrolytic capacitors higher temperatures force the evaporation of electrolytes, shortening the life time of the capacitors. In film capacitors higher temperatures may shrink the plastic film changing the capacitor's properties.

Pulse currents, especially in metallized film capacitors, heat the contact areas between end spray schoopage and metallized electrodes. This may reduce the contact to the electrodes, heightening the dissipation factor. For safe operation, the maximal temperature generated by any AC current flow through the capacitor is a limiting factor, which in turn limits AC load, ripple current, pulse load, etc.

A "ripple current" is the RMS value of a superimposed AC current of any frequency and any waveform of the current curve for continuous operation at a specified temperature. It arises mainly in power supplies including switched-mode power supplies after rectifying an AC voltage and flows as charge and discharge current through the decoupling or smoothing capacitor.

Ripple current generates heat within the capacitor body due to the ESR of the capacitor. The ESR, composed out of the dielectric losses caused by the changing field strength in the dielectric and the losses resulting out of the slightly resistive supply lines or the electrolyte depends on frequency and temperature.

For ceramic and film capacitors in generally ESR decreases with increasing temperatures but heighten with higher frequencies due to increasing dielectric losses. The types of capacitors used for power applications have a specified rated value for maximum ripple current.

These are primarily aluminum electrolytic capacitors, and tantalum as well as some film capacitors and Class 2 ceramic capacitors. Aluminium electrolytic capacitors, the most common type for power supplies, experience shorter life expectancy at higher ripple currents. Exceeding the limit tends to result in explosive failure. Tantalum electrolytic capacitors with solid manganese dioxide electrolyte are also limited by ripple current.

Exceeding their ripple limits tends to shorts and burning components. Exceeding this limit may destroy the internal structure and cause shorts.

The rated pulse load for a certain capacitor is limited by the rated voltage, the pulse repetition frequency, temperature range and pulse rise time. The peak current is defined as:. The permissible pulse current capacity of a metallized film capacitor generally allows an internal temperature rise of 8 to 10 K.

In the case of metallized film capacitors, pulse load depends on the properties of the dielectric material, the thickness of the metallization and the capacitor's construction, especially the construction of the contact areas between the end spray and metallized electrodes.

Capacitor Types: Types of Capacitor

High peak currents may lead to selective overheating of local contacts between end spray and metallized electrodes which may destroy some of the contacts, leading to increasing ESR. For metallized film capacitors, so-called pulse tests simulate the pulse load that might occur during an application, according to a standard specification. IEC part 1, specifies that the test circuit is charged and discharged intermittently. The pulse stress capacity is the pulse rise time.

The pulse load must be calculated for each application. A general rule for calculating the power handling of film capacitors is not available because of vendor-related internal construction details.

To prevent the capacitor from overheating the following operating parameters have to be considered:. Examples for calculations of individual pulse loads are given by many manufactures, e.

WIMA [51] and Kemet. An AC load only can be applied to a non-polarized capacitor. Capacitors for AC applications are primarily film capacitors, metallized paper capacitors, ceramic capacitors and bipolar electrolytic capacitors. The rated AC load for an AC capacitor is the maximum sinusoidal effective AC current rms which may be applied continuously to a capacitor within the specified temperature range. In the datasheets the AC load may be expressed as. Because dielectric losses increase with increasing frequency, the specified AC voltage has to be derated at higher frequencies.

Datasheets for film capacitors specify special curves for derating AC voltages at higher frequencies. If film capacitors or ceramic capacitors only have a DC specification, the peak value of the AC voltage applied has to be lower than the specified DC voltage.

AC loads can occur in AC motor run capacitors, for voltage doubling, in snubbers , lighting ballast and for power factor correction PFC for phase shifting to improve transmission network stability and efficiency, which is one of the most important applications for large power capacitors. These mostly large PP film or metallized paper capacitors are limited by the rated reactive power VAr.

Bipolar electrolytic capacitors, to which an AC voltage may be applicable, are specified with a rated ripple current. The resistance of the dielectric is finite, leading to some level of DC "leakage current" that causes a charged capacitor to lose charge over time. For ceramic and film capacitors, this resistance is called "insulation resistance R ins ". This resistance is represented by the resistor R ins in parallel with the capacitor in the series-equivalent circuit of capacitors.

Insulation resistance must not be confused with the outer isolation of the component with respect to the environment.

The time curve of self-discharge over insulation resistance with decreasing capacitor voltage follows the formula. The self-discharge constant is an important parameter for the insulation of the dielectric between the electrodes of ceramic and film capacitors.

For example, a capacitor can be used as the time-determining component for time relays or for storing a voltage value as in a sample and hold circuits or operational amplifiers. Insulation resistance respectively the self-discharge constant can be reduced if humidity penetrates into the winding.

It is partially strongly temperature dependent and decreases with increasing temperature. Both decrease with increasing temperature. For electrolytic capacitors the insulation resistance of the dielectric is termed "leakage current". This DC current is represented by the resistor R leak in parallel with the capacitor in the series-equivalent circuit of electrolytic capacitors. This resistance between the terminals of a capacitor is also finite. R leak is lower for electrolytics than for ceramic or film capacitors.

The leakage current includes all weak imperfections of the dielectric caused by unwanted chemical processes and mechanical damage. It is also the DC current that can pass through the dielectric after applying a voltage. It depends on the interval without voltage applied storage time , the thermic stress from soldering, on voltage applied, on temperature of the capacitor, and on measuring time.

The leakage current drops in the first minutes after applying DC voltage. In this period the dielectric oxide layer can self-repair weaknesses by building up new layers.

The time required depends generally on the electrolyte. Solid electrolytes drop faster than non-solid electrolytes but remain at a slightly higher level. The leakage current in non-solid electrolytic capacitors as well as in manganese oxide solid tantalum capacitors decreases with voltage-connected time due to self-healing effects.

Although electrolytics leakage current is higher than current flow over insulation resistance in ceramic or film capacitors, the self-discharge of modern non solid electrolytic capacitors takes several weeks. A particular problem with electrolytic capacitors is storage time. Higher leakage current can be the result of longer storage times.

These behaviors are limited to electrolytes with a high percentage of water. Organic solvents such as GBL do not have high leakage with longer storage times.

All ferroelectric materials exhibit piezoelectricity a piezoelectric effect. Because Class 2 ceramic capacitors use ferroelectric ceramics dielectric, these types of capacitors may have electrical effects called microphonics.

Microphonics microphony describes how electronic components transform mechanical vibrations into an undesired electrical signal noise. The resulting interference is especially problematic in audio applications, potentially causing feedback or unintended recording. In the reverse microphonic effect, varying the electric field between the capacitor plates exerts a physical force, turning them into an audio speaker. High current impulse loads or high ripple currents can generate audible sound from the capacitor itself, draining energy and stressing the dielectric.

Dielectric absorption occurs when a capacitor that has remained charged for a long time discharges only incompletely when briefly discharged.

Although an ideal capacitor would reach zero volts after discharge, real capacitors develop a small voltage from time-delayed dipole discharging, a phenomenon that is also called dielectric relaxation , "soakage" or "battery action".

In many applications of capacitors dielectric absorption is not a problem but in some applications, such as long- time-constant integrators , sample-and-hold circuits, switched-capacitor analog-to-digital converters , and very low-distortion filters , the capacitor must not recover a residual charge after full discharge, so capacitors with low absorption are specified.

In order to prevent shocks most very large capacitors are shipped with shorting wires that need to be removed before they are used. The separation of the electrodes and the voltage proof of the dielectric material defines the breakdown voltage of the capacitor. The breakdown voltage is proportional to the thickness of the dielectric.

Theoretically, given two capacitors with the same mechanical dimensions and dielectric, but one of them have half the thickness of the dielectric. With the same dimensions this one could place twice the parallel-plate area inside. This capacitor has theoretically 4 times the capacitance as the first capacitor but half of the voltage proof. Therefore, dielectric thickness does not affect energy density within a capacitor of fixed overall dimensions.

Using a few thick layers of dielectric can support a high voltage, but low capacitance, while thin layers of dielectric produce a low breakdown voltage, but a higher capacitance. This assumes that neither the electrode surfaces nor the permittivity of the dielectric change with the voltage proof. A simple comparison with two existing capacitor series can show whether reality matches theory.

In reality modern capacitor series do not fit the theory. For electrolytic capacitors the sponge-like rough surface of the anode foil gets smoother with higher voltages, decreasing the surface area of the anode. But because the energy increases squared with the voltage, and the surface of the anode decreases lesser than the voltage proof, the energy density increases clearly.

For film capacitors the permittivity changes with dielectric thickness and other mechanical parameters so that the deviation from the theory has other reasons. Comparing the capacitors from the table with a supercapacitor, the highest energy density capacitor family. Electrical parameters of capacitors may change over time during storage and application. The reasons for parameter changings are different, it may be a property of the dielectric, environmental influences, chemical processes or drying-out effects for non-solid materials.

In ferroelectric Class 2 ceramic capacitors, capacitance decreases over time. This behavior is called "aging". This aging occurs in ferroelectric dielectrics, where domains of polarization in the dielectric contribute to the total polarization. Degradation of polarized domains in the dielectric decreases permittivity and therefore capacitance over time. Aging is fastest near the beginning, and the absolute capacitance value stabilizes over time. The rate of aging of Class 2 ceramic capacitors depends mainly on its materials.

Generally, the higher the temperature dependence of the ceramic, the higher the aging percentage. The typical aging of X7R ceramic capacitors is about 2. The aging process of Class 2 ceramic capacitors may be reversed by heating the component above the Curie point.

Class 1 ceramic capacitors and film capacitors do not have ferroelectric-related aging. Environmental influences such as higher temperature, high humidity and mechanical stress can, over a longer period, lead to a small irreversible change in the capacitance value sometimes called aging, too. Film capacitors may lose capacitance due to self-healing processes or gain it due to humidity influences.

Electrolytic capacitors with non-solid electrolyte age as the electrolyte evaporates. This evaporation depends on temperature and the current load the capacitors experience. Electrolyte escape influences capacitance and ESR. Capacitance decreases and the ESR increases over time. In contrast to ceramic, film and electrolytic capacitors with solid electrolytes, "wet" electrolytic capacitors reach a specified "end of life" reaching a specified maximum change of capacitance or ESR.

End of life, "load life" or "lifetime" can be estimated either by formula or diagrams [67] or roughly by a so-called "degree-law". Supercapacitors also experience electrolyte evaporation over time.

Estimation is similar to wet electrolytic capacitors. Additional to temperature the voltage and current load influence the life time. Lower voltage than rated voltage and lower current loads as well as lower temperature extend the life time. Capacitors are reliable components with low failure rates , achieving life expectancies of decades under normal conditions. Most capacitors pass a test at the end of production similar to a " burn in ", so that early failures are found during production, reducing the number of post-shipment failures.

Reliability for capacitors is usually specified in numbers of Failures In Time FIT during the period of constant random failures. FIT is the number of failures that can be expected in one billion 10 9 component-hours of operation at fixed working conditions e.

For other conditions of applied voltage, current load, temperature, mechanical influences and humidity the FIT can recalculated with terms standardized for industrial [68] or military [69] contexts. Capacitors may experience changes to electrical parameters due to environmental influences like soldering, mechanical stress factors vibration, shock and humidity. The greatest stress factor is soldering. The heat of the solder bath, especially for SMD capacitors, can cause ceramic capacitors to change contact resistance between terminals and electrodes; in film capacitors, the film may shrink, and in wet electrolytic capacitors the electrolyte may boil.

A recovery period enables characteristics to stabilize after soldering; some types may require up to 24 hours. Some properties may change irreversibly by a few per cent from soldering. Electrolytic capacitors with non-solid electrolyte are "aged" during manufacturing by applying rated voltage at high temperature for a sufficient time to repair all cracks and weaknesses that may have occurred during production.

Some electrolytes with a high water content react quite aggressively or even violently with unprotected aluminum. This leads to a "storage" or "disuse" problem of electrolytic capacitors manufactured before the s. Chemical processes weaken the oxide layer when these capacitors are not used for too long. New electrolytes with "inhibitors" or "passivators" were developed during the s to solve this problem. For antique radio equipment, "pre-conditioning" of older electrolytic capacitors may be recommended.

This involves applying the operating voltage for some 10 minutes over a current limiting resistor to the terminals of the capacitor.

Capacitor Types: Types of Capacitor

Applying a voltage through a safety resistor repairs the oxide layers. Capacitors, like most other electronic components and if enough space is available, have imprinted markings to indicate manufacturer, type, electrical and thermal characteristics, and date of manufacture. If they are large enough the capacitor is marked with:. Also, the negative lead for leaded "wet" e-caps is usually shorter. Smaller capacitors use a shorthand notation. The most commonly used format is: Examples of short-marking of the rated capacitance microfarads: For very small capacitors like MLCC chips no marking is possible.

Here only the traceability of the manufacturers can ensure the identification of a type. As of [update] Capacitors do not use color coding. Aluminum e-caps with non-solid electrolyte have a polarity marking at the cathode minus side. Aluminum, tantalum, and niobium e-caps with solid electrolyte have a polarity marking at the anode plus side. Supercapacitors are marked at the minus side. Rectangular polymer capacitors , tantalum as well as aluminum, have a polarity marking at the anode plus side.

Discrete capacitors today are industrial products produced in very large quantities for use in electronic and in electrical equipment. All other capacitor types are negligible in terms of value and quantity compared with the above types. From Wikipedia, the free encyclopedia.

This article is about commercial discrete capacitors as customary components for use in electronic equipment. For the physical phenomenon, see Capacitance. For the explanation of the units of measure of capacitance, see Farad. Main article: Ceramic capacitor. Ceramic EMI suppression capacitors for connection to the supply mains safety capacitor.

Film capacitor. Radial style single ended for through-hole solder mounting on printed circuit boards. Electrolytic capacitor.

Axial, radial single ended and V-chip styles of aluminum electrolytic capacitors. Snap-in style of aluminum electrolytic capacitors for power applications. SMD style for surface mounting of aluminum electrolytic capacitors with polymer electrolyte. Radial single ended style of lithium ion capacitors for high energy density.

Frequency dependence of capacitance for film capacitors with different film materials. Dielectric absorption. Capacitor Polarized capacitor Electrolytic capacitor Bipolar electrolytic capacitor Feed through capacitor Trimmer capacitor Variable capacitor Capacitor symbols. Electronic color code. Polarity marking details. Cylindrical polymer capacitors have a polarity marking at the cathode minus side.

Electronics portal. Archived from the original PDF on 22 December Retrieved Bettacchi, D. Montanari, D. Zanarini, D. Orioli, G. Rondelli, A. Murarka; Moshe Eizenberg; A. Sinha , Interlayer dielectrics for semiconductor technologies in German , Academic Press, pp. Jacobs, p.

Retrieved 29 May Merker, K. Wussow, W. Conway Electrochemical Supercapacitors: Scientific Fundamentals and Technological Applications. Retrieved November 21, Conway in Electrochemistry Encyclopedia: Halper, James C. Ellenbogen March Volfkovich, A. Mikhailin, D. Bograchev, V.

Types & Functions of Capacitors | Sciencing

Sosenkin and V. Ujjal Kumar Sur Ed. Archived from the original on UL Online Certification Directory. Equipment and selection".

Know It All". The right equipment is essential for effective troubleshooting". EDN January 19, Retrieved 14 February Archived from the original PDF on Enabling Energy's Future". Maxwell Technologies. Capacitors combined with resistors and inductors in a circuit are used in electrical timing of events as well as in motors, fans, televisions, automobiles and many other consumer products and high-energy environments.

They are called polarized capacitors. The value of a capacitor is measured in capacitance, and capacitance is measured in units of Farad. Most capacitors usually have small Farad values called micro-Farad uF and pico-Farad.

A capacitor is designed in one of two formats: radial or axial. In the radial design, both leads of the capacitor are at the same end; in the axial design, the leads are at each end of the capacitor.

Polarized capacitors are usually big and electrolytic and are designed for direct current DC circuits. They usually have high capacitance. The disadvantages of polarized capacitors are that they have low breakdown voltage, shorter lifetimes and higher leakage of current.

They are also called bipolar capacitors. Used more often in alternating current AC circuits, they usually have small capacitance values in the micro-Farad and nano-Farad range. Some non-polarized capacitors tolerate voltage fluctuations up to volts without breaking down. They are used in computers, motherboards and simple circuit boards. Non-polarized capacitors are inexpensive and made of ceramic and mica, though a few are electrolytic.

Functions in Electrical Circuits Capacitors are used in electronic circuits as low-pass, high-pass and band filters. A filter is a circuit that allows current and voltage of a specified frequency and waveform to pass through.