Types Of Capacitors And Their Applications

7/21/2019 Types Of Capacitors And Their Applications

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Types Of Capacitors

And Their Applications



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Types Of Capacitors And TheirApplications

Introduction:

Capacitor is one of mostly used component in electronic

circuit design. It plays an important role in many of theembedded applications. It is available at dierent ratings.It consists of two metal plates separated by a nonconducting substance, or dielectric. A capacitor stores anelectrical charge between the two plates, The unit ofcapacitance is arads !". It is often storage depots foranalog signals and digital data





Common Types ofCapacitors

#. ilm Capacitors

$. Ceramic Capacitors

%. &lectrolytic Capacitors

'. (ariable Capacitors





Film Capacitors

ilm Capacitors comprising of a generally e)pansivegroup of capacitors with the distinction being in their

dielectric properties.

ilm Capacitors are available in almost any value andvoltages as high as #*++ volts.

They come in any tolerance from #+ to +.+#.

There are two types of -lm capacitors.

They are radial lead type and a)ial lead type.





Film Capacitors

The electrodes of -lm capacitors may be metaliedaluminium or inc.

It applied on one or both sides of the plastic -lm.





Film Capacitors

It resulting in metalied -lm capacitors called -lmcapacitors.

ilm capacitors additionally arrive in a combination ofshapes and case styles.

ilm Capacitors are sometimes called plastic capacitors.

It use polystyrene, polycarbonate or Teon as theirdielectrics.

These -lm sorts need a much thic0er dielectric -lm to

lessen the danger of tears.


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Film Capacitors

It is more suited to lower capacitance values and biggercase sies.

The -lm capacitors are physically larger and moree)pensive, they are not polaried.

It can be used in AC voltage applications, and they havemuch more stable electrical parameters.

1ependence of capacitance and dissipation factor.

ilm Capacitors can be applied in fre2uency stable Class #applications, replacing Class # ceramic capacitors.




CeramicCapacitors

Ceramic capacitors are used in high fre2uency circuitssuch as audio to 3

Ceramic Capacitors are the best choice for high fre2uencycompensation in audio circuits.

These capacitors are also called as disc capacitors.

Ceramic capacitors are made by coating two sides of asmall porcelain or ceramic disc with silver and are thenstac0ed together to ma0e a capacitor.




CeramicCapacitors

4ne can ma0e both low capacitance and highcapacitance in ceramic capacitors.




CeramicCapacitors

It can be made by changing the thic0ness of the

ceramic disc used.

They come in values from a few 5ico farads to #microfarad.

The voltage range is from a few volts up to manythousands of volts.

Ceramics are ine)pensive to manufacture and theycome with several dielectric types.




Electrolytic Capacitors

It is most prevalently used capacitors which have a

wide tolerance capacity.

&lectrolytic capacitors are available with wor0ingvoltages up to about *++(.

There are two types of electrolytic capacitor, tantalum

and aluminium in common.

Tantalums capacitors have ordinarily better e)hibition,higher value.





The dielectric properties of tantalum o)ide is muchsuperior to those of aluminium o)ide.





It has an easier lea0age current and better capacitancestrength which ma0es them suitable for obstructing,

decoupling, -ltering applications.

The thic0ness of the aluminium o)ide -lm andheightened brea0down voltage gives the capacitorse)ceptionally elevated capacitance values for their sie.

In a capacitor the foil plates are anodied by a dccurrent thus setting of the e)tremity of plat materialand con-rming polarity of its side.




VariableCapacitors




VariableCapacitors

A (ariable Capacitor is one whose capacitance may be

intentionally and repeatedly changed mechanically.

This type of capacitors utilied to set fre2uency ofresonance in 6C circuits.

To ad7ust the radio for impedance matching in antennatuner devices.




How to Know the Value ofCapacitors Capacitors are the essential components of an

electronic circuit without which the circuit cannot be

completed.

1ierent types of capacitors li0e &lectrolyticcapacitor, 1isc capacitor, Tantalum capacitor etc areused in circuits.

&lectrolytic capacitors have value printed on its bodyso that its pins can be easily identi-ed.

8sually the large pin is positive.




How to Know the Value ofCapacitors The blac0 band present near the negative terminal

indicates the polarity.

9ut in 1isc capacitors, only a number is printed on itsbody.

It is very dicult to determine its value in 5, ;5, u, n

etc.

or some capacitors the value is printed in terms of u,while in others a &IA code is used.




!ethods to Identify the Capacitor and toCalculate its Value

#.The number on the capacitor represents the capacitancevalue in 5ico arads.

or e)ample, < = <5

$. If the third number is ero, then the value is in 5 e.g. #++ =#++5

%. or a % digit number, the third number represents thenumber of eros after the second digit or e)ample, #+' = #+ >++++ 5

'. If the value is obtained in 5, it is easy to convert it into ;5

or u, 5 / #+++ = ;5 or n, 5 / #+, +++++ = u. or aca acitance value of #+' or #+++++ in , it is #++; or n or




Con"ersionFormula n ) #+++ = 5 5/#+++ = n 5/#,+++,+++ = u u )

#,+++,+++ = 5 u ) #,+++,+++/#+++ = nn=#/#,+++,+++,+++ u = #/ #+++,+++ .

The letter below the capacitance value determines thetolerance value.

'?% = '?% ;

or a ' digit number, if the 'th digit is a ero, then thecapacitance value is in p.

&.g. #*++ = #*++5




Con"ersionFormula If the number is 7ust a oating point decimal number, the

capacitance value is in u.

&.g. +.# = +.# u

If an alphabet is given below the digits, it represents adecimal and the value is in ;5 or n

&.g. $;$ = $.$ ;5

If the values are given with slashes, the -rst digit representsvalue in 8, second its tolerance and third its ma)imumvoltage rating

&.g. +.#/*/<++ = +.+# u / * / <++ (olt.





#ome Common $isc CapacitorsAre






@ithout a Capacitor, the circuit design will not becomplete since it has an active role in the functioning ofa circuit

The Capacitor has two electrode plates inside separatedby a dielectric material such as paper, mica.

@hat happens when the electrodes of the capacitor are

connected to a power supply

The capacitor charges to its full voltage and retains thecharge.






The capacitor has the ability to store current which ismeasured in terms of arads.

The capacitance of a capacitor depends on the area ofits electrode plates and the distance between them.

1isc capacitors do not have polarity.

Bo that they can be connected either way round.






1isc capacitors are mainly used for coupling /decoupling the signals.

The &lectrolytic capacitors on the other hand have

polarity.






If the polarity of the capacitor changes, it will e)plode.

&lectrolytic capacitors are mainly used as -lters, buers.

&ach capacitor has its own capacitance which is e)pressedas the Charge in the capacitor divided by the (oltage.

@hen you use a capacitor in a circuit, some importantparameters should be considered.






irst is its (alue. Belect a proper value.

&ither low or high value depending on the circuit design.

The value is printed on the body of most of the capacitorsin u or as &IA code.

In Color coded capacitors, the values are represented ascolor bands.

9y using a capacitor color code chart it is easy to identifythe capacitor.





Color Chart to Identify a Color CodedCapacitor

3esistors each band on the capacitor hasa value.





Color Chart to Identify a Color CodedCapacitor The value of the irst band is the irst number in the

color chart.

The value of the Becond band is the Becond number in thecolor chart.

The Third band is the multiplier as in the case of a resistor.

ourth band is the Tolerance of the capacitor.

The ifth band is the body of the capacitor which representsthe @or0ing voltage of the capacitor.

The 3ed color represents $*+ volts and Dellow represents'++ volts.

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Capacitor Tolerance and %or&in' "olta'e

Tolerance and @or0ing voltage are two importantfactors to be considered.

Eo capacitor has the rated capacitance and itmay vary.

Bo use a good 2uality capacitor li0e Tantalumcapacitor in sensitive circuits li0e oscillator

circuits.

The wor0ing voltage of the electrolytic capacitoris printed on its body.

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Capacitor Tolerance and %or&in' "olta'e

6ea0age current is another problem in capacitors.

Bome of the charge will lea0, even if the capacitor ischarging

This is verse in Timer circuits since the timing cycle

depends on the charge/discharge time of the capacitor.

6ow lea0age Tantalum capacitors are available and usethem in Timer circuits.

T Of C it A d Th i





(nderstandin' the )eset Capacitor Functionin !icrocontroller

A 3eset is used to startFup or to restart the AT<+C*#

microcontroller functionality.

A reset pin follows two conditions to start up themicrocontroller. They are

#" 5ower supply must be in the speci-ed range.

$" The reset pulse width duration must be at least twomachine cycles.

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The reset must be 0ept active until all two of the

conditions are respected.

In this type of circuit, the capacitor and resistorarrangement from the supply is connected to reset pinno. G.

@hile the supply switch is 4E, the capacitor startscharging.

At this time, capacitor acts li0e a short circuit in thebeginning.

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@hen reset pin set to HIH, the microcontroller goes tothe power on state and after some time the chargingstops.

@hen charging stops, the reset pin goes to groundbecause of the resistor.

The reset pin should go to high then go to low, thenprogram starts from begging.

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Ad"anta'es

6ong life, with little degradation over hundreds of

thousands of cycles.

6ow cost per cycle

ood reversibility

(ery high rates of charge and discharge.

&)tremely low internal resistance !&B3" and conse2uent

high cycle eciency !G* or more" and e)tremely low

heating levels.

High output power.

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$isad"anta'es The amount of energy stored per unit weight is considerably

lower than that of an electrochemical battery.

As with any capacitor, the voltage varies with the energy

stored.

Has the highest dielectric absorption of any type of capacitor.

Cells have low voltages > serial connections are needed to

obtain higher voltages.

(oltage balancing is re2uired if more than three capacitors areconnected in series.

6inear discharge voltage prevents use of the full energyspectrum.

T Of C it A d Th i





Applications

Capacitors have applications in bothelectrical and electronics.

They are used in -lter applications, energy storagesystems, motor starters and signal processingdevices.

Capacitors are used for power factor correction.

8se of capacitors includes smoothing the ripples fromAC in power supply, coupling and decoupling thesignals, as buers etc.

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Conclusion

The comparisons between thedierent types of capacitors are generally made with

regards to the dielectric used between the plates. Bomecapacitors loo0 li0e tubes, small capacitors are oftenconstructed from ceramic materials and then dipped intoan epo)y resin to seal them.

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Types Of Capacitors And Their Applications