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The industry of electronic circuits uses resistors of various different types available in the market. The properties of these resistors vary and are different for each type being ruled by their manufacturing and construction process.


By: S. Prakash


Over a time period, the resistors of various types which were and are being used in the production of electronics have undergone continuous change.

The resistors which were used previously consisted of lead as their component along with being very large in size when compared to the resistors of the present day which resulted in low performance level of the former.

The current day resistors are comparatively smaller in size along with performing at a high level.

Resistors of variable and fixed types

The most major and basic category in which a resistor can be differentiated is on their nature of being either of variable or fixed type. The applications for which these resistors of different types are used differ respectively.

Fixed Resistors: The resistor which is used most widely in the industry is the fixed resistors. The electronic circuits use the fixed resistors for correcting and setting the right and appropriate conditions within their circuits.

The determination of the values of the resistors is carried out in the circuit’s design phase. These values are not required to be adjusted or changed in any manner with respect to the circuit.

The decision as to which resistor type needs to be used is dependent on the various circumstances in which they are to be used. These resistor types have been described in further detail in the subsequent sections.

Variable Resistors: The variable resistors consist of two elements, namely a fixed resistor element. The main element of the resistor is tapped onto by the slider present in the resistor.



Thus, this provides the resistor’s components with three connections. Out of these three connections, the fixed element is fixed to the two connections while the slider is the third connection.

Thus, this enables the components to act as an agent of the variable potential divider.

This also required that they use the three connections altogether. The variable resistance can be provided to the resistor by connecting the one end of the resistor with the slider.

Potentiometers, presets and rheostats are some of the common examples of variables resistors

Resistors of Fixed Types

The various different fixed resistor types are as follows:

Carbon composition: The carbon composition resistors were very common previously but the currently their usage has decreased considerably.





The carbon resistors are manufactured by mixing the granules of the carbon with an element which acts as a binder and this mixture in turn is made in the shape of small rods.

The carbon resistors had a disadvantage in terms of suffering from a very high negative temperature coefficient.

This is due to their comparatively large size when viewed from the current day standards.

The carbon composition resistors also suffered another downfall wherein due to aging of the resistor with time or an exposure to excessive heat, the carbon composition resistor goes through irreversible changes which are erratic and large.

Additionally, a large amount of noise is generated in the carbon composition resistor when the current flows through it because of the carbon’s granular nature and its association with the binder.

Carbon Film (CFR 5%): The carbon film resistor is manufactured by the induction of the process of a hydrocarbon’s cracking into a former made up of ceramic.



The resistance of the film which is deposited as a result of the above process is set by making a cut into the film in the shape of helix. This has resulted in very high inductance in the carbon film resistors and thus most of the RF applications cannot use it much.

A -900 ppm/ºC to -100 ppm/ºC of temperature coefficient is exhibited by the carbon film resistors. A ceramic tube or a conformal epoxy coating is used to protect the carbon film.

Metal Oxide Film (MFR 1%): The metal oxide film resistor has come to become the resistor which is used in the current day industry at a wide scale along with another resistor type of the metal film type.





The metal oxide film resistor type uses a film of metal oxide instead of a carbon film to be deposited on the ceramic rod.

The deposition of the metal oxide which can be found on the ceramic rod can include tin oxide. There are two ways in which the component’s resistance is adjusted.

Firstly, at the initial stages of the manufacturing process, the deposited layer’s thickness is controlled. Thereafter the adjustment is done in more accurate way by cutting a grove in the shape of helical form in the film.

Again, as in the previous case, the conformal epoxy coating is heavily coated on the film to protect it.

The ±15 ppm/ºK of temperature coefficient has been observed in the metal oxide film resistor which results in a very high and superior function of this resistor when compared to any other resistor which is carbon based.

 Additionally, the tolerance levels to which these resistors are supplied are very close including the standard tolerance levels of ±2%, ±1%, and ±5% being available.

Also, when compared with the resistors which are carbon based, there is very low exhibition of noise in these resistors.

Metal Film: There is a great similarity which can be observed between the metal oxide film resistor and the metal film resistors in terms of their performance and appearance.

A metal film is used by this resistor in place of the metal oxide film which is used in the metal oxide film resistor. The metal film which is used in the resistor can include nickel alloy.

Wire Wound: The applications which require very high power in general use this type of resistor. A wire is wounded around a former in order to manufacture this type of resistors.





The resistance of these wires is higher than that of the normal resistance. The varieties of these resistors which are expensive consist of the wire which is wound on a former made up of ceramic along with a cover of the silicone or citreous enamel over it.

The temperature coefficient of these resistors is very low along with a reliability of very high level being exhibited by these resistors when exposed to high power which enables it to operate at high performance level.

But these properties are also dominated by various other factors such as type of the wire being used, type of former being used, and more.

Thin Film: The majority of the resistors which are of surface mount types use the technology of the thin film. The resistors based on this technology are used widely in the current day industry where the number goes up to billions here.

Non-Leaded and Leaded types of Resistors

The manner in which the components or the resistors are connected acts as an important determinant of the differentiation of the components and the resistors.

The manner in which the components were connected previously has changed over the time majorly due to the use of the techniques of mass production and the circuit boards being used at a widespread level.

This is especially true for the components which the mass production process incorporates.

On the basis of the method of connection, the two major categories of the resistors are as follows:

Leaded Resistors: Since the times when the electronic components had first come into use, the leaded resistors had also come into use since those times.

The lead which came from the element of the resistor were required wherein the components were required to be connected in various different forms to the terminal posts.

Their usage has not stopped till date and only technique has changed wherein in the current practices where there is more use of the printed circuit boards, the holes present in the boards are used to insert the lead and then the reverse side is used to solder it where one can find the tracks.

Surface Mount Resistors: The since the time when the technology of the surface mount have been introduced, there has been a significant increase in the surface mount resistors.



The technology which is used to manufacture the surface mount resistor is the thin film technology. Through this technology, the resistor can obtain the values in full range.

In this post we learn regarding the basics of capacitor, and also regarding the various types of capacitors which are commonly available in the market and used in most electronic circuits.


By: S. Prakash.

The performance parameters of every capacitor are different and thus their applications also differ accordingly.

One of the electronic components’ forms which is used widely is the electronic capacitors. Apart from this, the other capacitors used in the industry include ceramic, silver mica, electrolytic, plastic, tantalum, and others.

Each type of the capacitor is used in various applications according to their respective disadvantages and advantages.

It is quintessential that the right type of capacitor must be selected as the circuit in which the capacitor is used is greatly by the capacitor.

Thus, in case a correct type of capacitor is not selected to insert in the circuit on the basis of its parameters, it can result in the improper or faulty functioning of the circuit.

Basics of the capacitors

The physical laws which basically govern the various types of capacitors are same and are adhered to accordingly.

These basic laws determine various parameters of the capacitors such as how the capacitor would operate, the value of the capacitor, and its capacitance (the maximum amount of charge which the capacitor will hold).

Thus, the basic theory on which capacitors are built and work enables to understand the different capacitors forms and how these can be or are used.

Note: Even though there have been numerous developments in the field of dielectrics, the basic laws on which the capacitors work has not changed and they apply to date.

Types of Capacitors and Dielectrics

As discussed above, although the basic laws on which the capacitors work, the properties of the capacitors differ enormously because of the manner in which each type of the capacitor is constructed.

The various properties which various types of capacitors possess is given by their main element which is located between the two plates of the capacitor and is known as “dielectric”.

The dielectric constant of the capacitor can impact the capacitance level which the capacitor can achieve at a given specific volume. Also, various capacitors of different types can be found to be polarized in nature wherein the voltage running across the capacitor is tolerated in one single direction only.

On the other hand, various capacitors of different types can be found to be non-polarized in nature wherein the voltage running across the capacitor is tolerated in both the direction.

The capacitors are commonly named on the basis of the nature of the dielectric which is present in the capacitor.

This is indicative of the general properties which the capacitor will be exhibiting along with the various different types of circuit functions where they can be used.

Overview of capacitors and its different types

The various types of capacitors which are being used are as follows:

Ceramic Capacitor: 

The capacitor namely, ceramic capacitor is used for multiple applications including RF and audio.

The range of the values of the ceramic capacitor is between few picofarads and 0.1 microfarads. The ceramic capacitors are the most widely used in the industry since it the most reliable and cheap type of capacitor available.

Also, another reason for its common and wide usage is that the loss factor of the ceramic capacitor is very low. But the loss factor of the capacitor is also dependent on the dielectric which is used in the capacitor.

The ceramic capacitors are used in both the formats of surface mount and leaded because of the constructional properties of the capacitors.

Electrolytic Capacitor: 

 

One type of capacitor which is polarized in nature is electrolytic capacitors.

The capacitance values which are offered by the electrolytic capacitor is very high which ranges more than 1µF. the electrolytic capacitors are used in the industry commonly for the applications which are conducted on low frequency such as decoupling applications, power supplies, and applications of audio coupling.

This is because these applications have the frequency limit of nearly 100 kHz.

Tantalum Capacitor: 

Another type of capacitor which is polarized in nature is tantalum capacitor. The capacitance level provided by the tantalum capacitor at their volume is very high.

One of the drawbacks of the tantalum capacitor is that there is no tolerance in the tantalum capacitor towards reverse biasing which can result in the explosion of the capacitor when exposed to stress.

Another drawback is that it has very low tolerance to the ripple currents and thus they should not be exposed to high voltages (such as voltages which is higher than their working voltage) and high ripple current. The tantalum capacitors are available in both the formats of surface mount and leaded.

Silver Mica Capacitor: 

Although the usage of the silver mica capacitors have decreased significantly in the current era, the stability provided by the silver mica capacitors are still very high along with providing high accuracy and low loss.

Also, there is sufficient space available in the silver mica capacitors. The applications where they are primarily used include the RF applications.

The maximum values to which the silver mica capacitor is limited to is approximately 100pF.

Polystyrene Film Capacitor: 

 

 

The polystyrene film capacitors provide capacitor of close tolerance wherever required. Also, these capacitors are relatively cheaper than that of other capacitors.

The dielectric sandwich or the plates present in the polystyrene film capacitors are rolled together which results in the shape of the capacitor in tubular form.

The placement of the dielectric sandwich and shape of the capacitor limits the response of the capacitor to high frequencies due to addition of inductance and thus responds to only few 100kHz.

The general availability of the polystyrene film capacitors is in the form of leaded electronics components.

Polyester Film Capacitor: 

 

 

The tolerance provided by the polyester film capacitor is very low and thereby these capacitors are used in situations when the prior consideration is the cost.

The tolerance level of a large percentage of the polyester film capacitors available is either 10% or 5% and this is considered as sufficient for a range of applications.

The general availability of the polyester film capacitors is in the form of leaded electronics components.

Metallized Polyester Film Capacitor

The metallized polyester film type of capacitors consists of polyester films which are metallized and in every other sense, it is similar to the polyester film capacitors or another form of it.

One of the advantages which is achieved by metallic polyester film is that it makes the electrodes of very small width and thereby enabling the encasement of the capacitor in a package of very small sizes as well.

 The general availability of the metallized polyester film capacitors is in the form of leaded electronics components.

Polycarbonate capacitor: 

PPC or Polypropylene Capacitor: 

Glass Capacitors: 

Supercap: 

The other names by which the supercap is known are ultracapacitor or supercapacitor.

The capacitance values of these capacitors are very large as such is their name. The capacitance levels of the ultracapacitor go nearly towards many thousand Farads.

The ultracapacitor is used in the industry for providing a supply of memory hold-up along with various uses within the realm of automotive applications. The different major types of the capacitors are included under the supercap.

Along with them, there are various other capacitor types of capacitors which are used when the applications are specialized in nature.

The identification of the capacitors is majorly done through their parameters such as values which are marked over the cases of the capacitors. In order to display the parameters in a manner which is compact, the markings of the parameters are done in the form of a code.