Types Of Capacitors And Their Applications

Types Of Capacitors And
Their Applications

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Types Of Capacitors And Their
Applications
Introduction:
 Capacitor is one of mostly used component 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. A capacitor stores an electrical
charge between the two plates, The unit of capacitance is Farads (F). It is
often storage depots for analog signals and digital data

Applications
Common Types of Capacitors
1. Film Capacitors
2. Ceramic Capacitors
3. Electrolytic Capacitors
4. Variable Capacitors

Applications
Film Capacitors
 Film Capacitors comprising of a generally expansive group of
capacitors with the distinction being in their dielectric properties.
 Film Capacitors are available in almost any value and voltages as high
as 1500 volts.
 They come in any tolerance from 10% to 0.01%.
 There are two types of film capacitors.
 They are radial lead type and axial lead type.

Applications
Film Capacitors
 The electrodes of film capacitors may be metalized aluminium or zinc.
 It applied on one or both sides of the plastic film.

Applications
Film Capacitors
 It resulting in metalized film capacitors called film capacitors.
 Film capacitors additionally arrive in a combination of shapes and case
styles.
 Film Capacitors are sometimes called plastic capacitors.
 It use polystyrene, polycarbonate or Teflon as their dielectrics.
 These film sorts need a much thicker dielectric film to lessen the danger
of tears.

Applications
Film Capacitors
 It is more suited to lower capacitance values and bigger case sizes.
 The film capacitors are physically larger and more expensive, they are not
polarized.
 It can be used in AC voltage applications, and they have much more stable
electrical parameters.
 Dependence of capacitance and dissipation factor.
 Film Capacitors can be applied in frequency stable Class 1 applications,
replacing Class 1 ceramic capacitors.

Applications
Ceramic Capacitors
 Ceramic capacitors are used in high frequency circuits such as audio to RF
 Ceramic Capacitors are the best choice for high frequency compensation
in audio circuits.
 These capacitors are also called as disc capacitors.
 Ceramic capacitors are made by coating two sides of a small porcelain or
ceramic disc with silver and are then stacked together to make a
capacitor.

Applications
Ceramic Capacitors
 One can make both low capacitance and high capacitance in
ceramic capacitors.

Applications
Ceramic Capacitors
 It can be made by changing the thickness of the ceramic disc used.
 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 with
several dielectric types.

Applications
Electrolytic Capacitors
 It is most prevalently used capacitors which have a wide tolerance
capacity.
 Electrolytic capacitors are available with working voltages up to
about 500V.
 There are two types of electrolytic capacitor, tantalum and
aluminium in common.
 Tantalums capacitors have ordinarily better exhibition, higher value.

Applications
 The dielectric properties of tantalum oxide is much superior to those
of aluminium oxide.

Applications
 It has an easier leakage current and better capacitance strength
which makes them suitable for obstructing, decoupling, filtering
applications.
 The thickness of the aluminium 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
of the extremity of plat material and confirming polarity of its side.

Applications
Variable Capacitors

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

Applications
How to Know the Value of Capacitors?
 Capacitors are the essential components of an electronic circuit
without which the circuit cannot be completed.
 Different types of capacitors like Electrolytic capacitor, Disc
capacitor, Tantalum capacitor etc are used in circuits.
 Electrolytic capacitors have value printed on its body so that its
pins can be easily identified.
 Usually the large pin is positive.

Applications
How to Know the Value of Capacitors?
 The black band present near the negative terminal indicates the
polarity.
 But in Disc capacitors, only a number is printed on its body.
 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
a EIA code is used.

Applications
Methods to Identify the Capacitor and to Calculate
its Value
1.The number on the capacitor represents the capacitance value in Pico Farads.
For example, 8 = 8PF
2. If the third number is zero, then the value is in P e.g. 100 = 100PF
3. For a 3 digit number, the third number represents the number of zeros after
the second digit For example, 104 = 10 – 0000 PF
4. 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.

Applications
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 4th digit is a zero, then the capacitance value
is in pF.
 E.g. 1500 = 1500PF

Applications
Conversion Formula
 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.

Applications
Some Common Disc Capacitors Are

Applications
 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.
 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.

Applications
 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.

Applications
 Disc capacitors are mainly used for coupling / decoupling the signals.
 The Electrolytic capacitors on the other hand have polarity.

Applications
 If the polarity of the capacitor changes, it will explode.
 Electrolytic capacitors are mainly used as filters, buffers.
 Each capacitor has its own capacitance which is expressed as the Charge
in the capacitor divided by the Voltage.
 When you use a capacitor in a circuit, some important parameters should
be considered.

Applications
 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.
 By using a capacitor color code chart; it is easy to identify the capacitor.

Applications
Color Chart to Identify a Color Coded Capacitor
 Resistors each band on the capacitor has a value.

Applications
Color Chart to Identify a Color Coded Capacitor
 The value of the First band is the First number in the color chart.
 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.
 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.

Applications
Capacitor Tolerance and Working voltage
 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 Tantalum capacitor in
sensitive circuits like oscillator circuits.
 The working voltage of the electrolytic capacitor is printed on
its body.

Applications
Capacitor Tolerance and Working voltage
 Leakage current is another problem in capacitors.
 Some of the charge will leak, even if the capacitor is charging
 This is 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.

Applications
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 start up the microcontroller.
They are
1) Power supply must be in the specified range.
2) The reset pulse width duration must be at least two machine cycles.

Applications
Microcontroller
 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, capacitor acts like a short circuit in the beginning.

Applications
Microcontroller
 When reset pin 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 ground because of the
resistor.
 The reset pin should go to high then go to low, then program starts
from begging.

Applications
Advantages
 Long life, with little degradation over hundreds of thousands of cycles.
 Low cost per cycle
 Good reversibility
 Very high rates of charge and discharge.
 Extremely low internal resistance (ESR) and consequent high cycle
efficiency (95% or more) and extremely low heating levels.
 High output power.

Applications
Disadvantages
 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.
 Voltage balancing is required if more than three capacitors are connected in
series.
 Linear discharge voltage prevents use of the full energy spectrum.

Applications
Applications
 Capacitors have applications in both electrical and electronics.
 They are used in filter applications, energy storage systems, motor
starters and signal processing devices.
 Capacitors are used for power factor correction.
 Use of capacitors includes smoothing the ripples from AC in power
supply, coupling and decoupling the signals, as buffers etc.

Applications
Conclusion
 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.

Types Of Capacitors And Their Applications

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