The Engineering Projects

Introduction to 5n50

Hey Everyone! I hope you are doing great. I am back to give you daily dose of information so you can excel in your life. Today, I am going to uncover the details on the Introduction to 5n50. It is an N-Channel MOSFET which is designed to obtain high switching performance and minimum on state resistance in an effective way. It is a unipolar device which comes with three terminals called drain gate and source. I'll try to cover everything in detail related to this N-Channel MOSFET. Let's hop on the board and dive in the details to unlock the features of this transistor.

Introduction to 5n50

• 5n50 is an N-Channel MOSFET that comes in advanced DMOS, planer stripe technology.
• It is designed to achieve high switching performance. As it is an N-Channel MOSFET, so here conduction will be carried out by the movement of electrons.
• 5n50 usually consists of three terminals called source gate and drain. Conduction is achieved when electron emit from the source terminal and collected by the drain terminal.
• Conducting path between drain and source is called channel. Small positive voltage at the gate terminal is used to control the conduction between drain and source terminal.

• As we increase the initial input voltage at the gate terminal it will allow the conduction path between source and drain to increase, hence helps in increasing the overall conductivity of the channel.
• In this MOSFET, gate is practically isolated from drain and source and there lies an insulating layer between the gate and the body of the transistor. Sometimes it is referred as IGFET( Insulated Gate Field Effect Transistor), as gate is insulated and draws no current.

5n50 Pinout

This N-Channel MOSFET consists of three terminals which are given below. 1: Source 2: Gate 3: Drain  

• Voltage at the gate terminal is used to control the conduction between source and drain. And conduction is carried out by the movement of electrons.
• It comes in three different package named as TO-220, TO-252 and TO-262 receptively.
• All three types come with same characteristics but with different power dissipation values.

Working of 5n50

• As it is N-Channel MOSFET, so conduction will be done by the movement of electrons.
• In 5n50, the drain and source are composed of N type material while body and substrate is composed of P type material.
• The gate of this transistor is used composed of layer of poly-silicon.
• The addition of silicon dioxide on the layer of substrate gives the typical metal oxide semiconductor construction. MOS.
• The layer of silicon dioxide is a dielectric material so it will act as a capacitor where one of its electrodes will be replaced by the semiconductor.

• As we apply positive voltage at the MOS composition, it will alter the charge distribution in the semiconductor. With the addition of positive voltage, the holes present under the oxide layer will encounter a force and allow the holes to move downward. The depletion region will be accumulated by the bound negative charges which are connected with acceptors atoms.
• The accumulation of electrons at the p-type substrate increases the conductivity between the source and drain. At this point the electrical properties of p-type substrate will consistently inverts, allowing the substrate to change into n-type material.
• The addition of positive voltage at the gate terminal will control the movement of electron in the conducting channel between source and drain. The more we increase the voltage the more it will increase the overall width of conducting channel, hence ultimately increases the conductivity of transistor.
• Main advantage of this transistor over other bipolar junction transistor is that it needs no input current to handle the load current.

Maximum Ratings 5n50

Following figures shows the absolute maximum rating of 5n50.

• Drain-Source voltage is 500 V.
• Drain current is 5 A.
• Power dissipation is 38, 54, 125 W for different composition of MOSFET that comes  in three forms TO-220, TO-252, TO-262 repectively.

Applications

• 5n50 is an N-Channel MOSFET which is widely used in many electronic applications.
• It is used in active power factor correction.
• The ability of transistor to change its conductivity by the addition of positive voltage at the gate terminal is used for efficient amplification purpose.
• It is useful in many efficient power supplies where high switching is required.
• Some electronic lamps use this MOSFET for driving purpose.

That's all for today. If you have any query or question you can ask me in the comment section below. I'll try my best to help you in this regard. Thanks for reading the article. Stay Tuned for next article!

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Step 1. Making a research

This step is the most important. What does it mean? In this context, research means gathering of information about the overall market as well as about your customers. Why is it necessary? It helps you not only to improve your service but to attract new buyers too. As a consequence, you will have an increased profit from your business. To do that you need to consider people you are dealing with. Understanding your customers' behavior will bring a lot of benefits. Where do they get an information? What do they need? What are they looking for? Who are they? and so on. Another important thing here is to pay attention to your competitors. Watch after their successful and unsuccessful strategies in order to improve your own. As it was said above you need to gather information about the market itself. Understand the trends will help you to promote the right products or services.

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After you have gathered as much information as you could, you can start planning. Setting real objectives are very important as well as looking for the ways to achieve them. The first mistake here that people usually do is setting too many goals. The fewer goals you have the more resources you can spend on each of them, which makes your aims are more achievable. Notice, that content marketing can be used for near every purpose from promoting SEO up to customer's retention. Understanding of the amount of time that is needed is very useful, setting time frames is very important. Time frames are closely connected with the number of your available investments. Take it into account.

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It is about the realization of your plan. How are you going to reach your goals? Do you want to see a lot of texts, videos, some interactive content? It includes also the topics you are going to come with, it's promotion and publishing etc. This is all about making your plans real. In most cases, it is better to think about taking some additional temporary help from professionals. Ffor example, if you need a lot of texts it is better to hire content writers than do it by yourself. They can give you some pieces of advice as well as their work will have much higher quality.

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What is MOSFET? Definition, Full Form, Symbol & Working

Hey Guys! I hope everyone's fine. Today, we are going to have a look at What is MOSFET? We will cover MOSFET Definition, Full Form, Symbol, Working & Applications in detail.

MOSFETs are commonly used in many electronic applications. A number of MOSFETs are added in tiny memory chips or microprocessors that are widely used in cell phones and laptops. It is a voltage-controlled device that is used for amplification and switching purposes. I'll try to touch every area related to MOSFET. Let's get started.

What is MOSFET?

• MOSFET is an advanced type of FET, manufactured with controlled oxidation of semiconductor, having 4 Terminals, named:
  • Drain(D)
  • Gate(G)
  • Source(S)
  • Body(B)

where,

• Gate(G) Terminal is practically insulated from the entire assembly by a thin layer of Silicon-oxide(SiO2).
• Body(B) Terminal is connected internally with Source(S) Terminal & thus the MOSFET package consists of 3 pins.

• The below figure shows the MOSFET package, construction & symbol: (we will discuss them in detail below)

MOSFET Full Form

• MOSFET stands for "Metal-oxide Semiconductor Field Effect Transistor".

MOSFET Symbol

• Although MOSFET has 4 terminals, but as I have mentioned before, the 4th terminal is internally connected with the Source terminal & thus the package consists of 3 Pins, so as the MOSFET Symbol.
• MOSFET symbols are shown in the below figure:

Why MOSFET?

• Unlike BJT, MOSFET requires almost no input current & controls heavy current at the output.
• MOSFETs are quicker in operation than FETs, thus used in fast switching applications.
• FET has high drain resistance, while it's too low in MOSFET.

History of MOSFET

• MOSFET laid the foundation of modern electronics back in 1959 when it was invented at Bell lab by Mohammad Attala and Dawon kahng.
• MOSFET was presented to the world in the 1960s with a few tweaks in the original version of the device.
• In the 1960s the invention of MOSFETs led to rapid exponential growth of the semiconductor world, it enabled the use of semiconductors in integrated circuits and microcontroller units.
• MOSFET is compact and easy to use, which is why it is always in demand for mass production.

MOS Revolution

• The evolution and development of MOSFET led to a revolution in electronics which is labeled as the MOS revolution or MOSFET revolution.
• The birth of the Metal Oxide Semiconductor Field-effect transistor was regarded and cherished as the birth of modern electronics.
• MOSFET is one of the most widely mass-produced technologies of this era. Can you imagine the count of MOSFETs manufactured to date? By 2018 it was 13 Sextillion, unbelievable! Isn’t it?

MOSFET Construction

• Let's understand the construction of N-type MOSFET: In N-type MOSFET, two highly doped N regions are diffused into a single lightly-doped P substrate.
• Silicon Oxide(SiO2) layer is placed over Gate Terminal to create the insulation.
• Aluminum Probes are used for connecting terminals i.e. Gate, Drain & Source to respective regions.
• Silicon oxide(SiO2) layer is the main difference between FET & MOSFET and thus MOSFET is sometimes referred to as "FET with Insulated Gate" or "IGFET(Insulated Gate Field Effect Transistor)".
• Because of this oxide layer, MOSFET acts as a voltage controlled IC i.e. voltage at Gate Terminal decides the conductivity between drain and source.
• The conduction path between Source(S) and Drain(D) is called channel & its width is controlled by the Gate(G) voltage in MOSFET.
• MOSFET is a unipolar device i.e. conduction of current is carried out by the movement of either electrons or holes(majority charge carriers).
• N-Channel MOSFET internal Construction is shown in the below figure:

 

Types of MOSFET

MOSFETs are further divided into two types. MOSFET types are as follows:

1. N-Channel MOSFET.
2. P-Channel MOSFET.

Let's understand these MOSFET types, one by one:

N-Channel MOSFET

• In N-Channel MOSFET, a single P-layer is present between two N-layers & current flows because of negatively charged electrons(termed as majority charge carriers).
• Below figure shows the symbol, construction & block diagram of N-channel MOSFET:

P-Channel MOSFET

• In P-Channel MOSFET, single N-layer is present between two P-layers & current flows because of positively charged holes(termed as majority charge carriers).
• Below figure shows the symbol, construction & block diagram of P-channel MOSFET:

MOSFET Working Principle

In order to understand the working principle of MOSFET, we have to first understand its operational modes. Depending on the polarity of Gate Voltage, MOSFET operates in two modes, named:

1. Enhancement Mode.
2. Depletion Mode.

MOSFET Enhancement Mode & Depletion Mode

Let's take the example of an N-type MOSFET:

• If a positive voltage is applied at the Gate Terminal of N-type MOSFET, it starts conducting by creating a bridge between Drain & Source and termed as acting in Enhancement Mode.
• When a positive voltage is applied at the Gate terminal, the surface below the oxide layer starts attracting electronics while repelling holes.
• Hence, electrons get accumulated below the silicon oxide layer.
• As we increase the voltage at Gate Terminal, more electrons get attracted & thus conduction increases in N-Type MOSFET.
• If we reverse the voltage at Gate Terminal, N-type MOSFET will repel electrons and attract holes, thus the connection between Drain & Source will break & MOSFET is said to be in Depletion Mode.
• Both Operating Modes of N-Type MOSFET is shown in below figure:

MOSFET Characteristics

• In the composition of enhancement MOSFET, there must be minimum input gate-source voltage is applied to the gate before it starts conducting, this minimum voltage is called threshold voltage.
• In order to conduct these enhancement amplifiers, the gate-source voltage Vgs must be greater than the threshold voltage.
• Drain current Id will increase by increasing the forward biasing of MOSFET, making them suitable for efficient amplifier circuits.
• When we apply a fixed voltage between the drain and source Vds, we can plot the values of drain current Id for different values of the voltage across gate and source Vgs.

• These VI characteristics show the transconductance of the MOSFET. This transconductance is the ratio between the output drain current to the input gate-source voltage.
• For a fixed value of Vds, the slope of transconductance can be found as

gm= ?Id/?Vds

• This ratio is termed as transconductance which is a short form of "transfer conductance". The SI unit of transconductance is Siemens which is ampere per volt.
• The voltage gain of this MOSFET increases with the increase in transconductance and value of the drain resistor.
• At Vgs=0, N-Type enhancement MOSFET acts like an open switch or normally off, because field-effect won't be able to open the N-Type channel around the gate.
• Thus transistor will fall under the "cut-off" region at this point. The OFF condition of the MOSFET is represented by the dotted line, unlike the depletion region which shows a continuous line, showing the conduction region of the transistor.

• As we apply gate-source voltage Vgs at the gate terminal, it will start to conduct in the region between source and drain.
• The voltage at which transistors start conducting is known as threshold voltage and is represented by Vth.
• As we increase the gate-source voltage it will allow the conducting channel to go wider and ultimately increases drain current Id.
• It is important to note that the gate never conducts as it is practically isolated from the conducting channel between source and drain. MOSFET encompasses high impedance which is useful in many electrical amplifying circuits.
• If the threshold voltage is greater than gate-source voltage, then the channel will not conduct, it will only conduct when threshold voltage will be less than gate-source voltage Vgs.
• In the conduction or saturation region drain current can be calculated as
• Id= K(Vgs-Vth²)
• It is important to note that values of the threshold voltage Vth and K(conduction parameter) are different for different eMOSFET, these values don't vary physically as they come by default during the composition of the material from which transistors are made.
• It is clear from the figure above that graph on the right side starts as a parabola and then it becomes linear, and it gives the slope of the characteristic curve that increases with the increase in drain current for a fixed value of drain-source voltage Vds.
• In order to put the MOSFET in ON state, the gate of the transistor must be biased from its given threshold level.
• Biasing of gate terminal can be achieved using two different methods i.e. Zener diode biasing, and drain feedback biasing. Before biasing you must take one point into consideration that gate voltage must be greater than source by a value greater than the threshold voltage.

MOSFET as a switch

• It is the most basic and widely known application of the MOSFET.
• Consider the following circuit diagram, an N channel MOSFET is used in the enhanced mode to operate the lamp.
• When the positive voltage VGS is applied to the gate of the MOSFET, a channel is established and the lamp is turned ON.

• Similarly, when the gate voltage is zero the lamp turns off.
• MOSFET can only work as an analog switching circuit if it operates between the cut off region when the gate-source voltage is zero up to the saturated region where the VGS becomes saturated, you can go through the complete process by studying the characteristics curve of the MOSFET we have discussed in the earlier section.
• The circuit which we are discussing has a very small amount of resistive load, if you want to protect your MOSFET from overloading you need to connect it to a relay or a diode. If you are not providing enough protection to your MOSFET, you would eventually damage it.

Comparison of MOSFET with Other Transistors

MOSFET was practically designed to make amends in the performance of Junction Field-effect Transistors because they had very high drain resistance, a very slow processing speed, and they were a bit noisy as well. We have been discussing transistors lately and we are done with the detailed outlook of other transistors such as bipolar junction transistor and field-effect transistor as well, so let us compare all the three main types to summarize the concepts. It would help you revise the previously learned concepts as well.

MOSFET vs BJT

• The major difference between BJT and MOSFET is that BJT is a bipolar device in which conductivity is carried out by the movement of both electrons and holes while MOSFET is a uni-polar device in which conduction is carried out by the movement of electrons or holes.
• The three terminals in BJT called emitter base collector are analogous to MOSFET three terminals called source gate and drain respectively.
• Another area where MOSFET differs from BJT is that there is no direct connection between the gate and conducting channel of source and drain, unlike BJT where a small current at the base side is used to control the large current at the emitter and collector side. That's the reason MOSFET is also named IGFET (Insulated Gate Field Effect Transistor).
• BJT is a current-controlled device meanwhile MOSFET is a voltage-controlled device, for a better understanding you can read the article to know how a MOSFET is a voltage controlled device.
• MOSFET is preferably used in analog circuits and BLDC motors but bipolar junction transistors are not the first choice in this regard.
• We mainly use BJT for performing low current functions on the parallel lines MOSFET are implied in high power applications, don't worry we will discuss the appliances of MOSFET in later sections.

MOSFET vs JFET

Both MOSFET and JFET belong to the same family of field-effect transistors.

• MOSFET has four components meanwhile the JFET has three components, three components namely the base source and drain are the same meanwhile the only different component is the Body of the MOSFET.
• MOSFET has a higher input impedance than the JFET.
• MOSFET has higher drain resistance than JFET because of the already established conduction channel of MOSFET.
• MOSFET make less noise than the JFET
• JFET is less costly and easy to manufacture because of the absence of a metal oxide layer that is present in MOSFET.
• MOSFET can easily be damaged due to low input capacitance meanwhile a higher input capacitance saves the JFET from immediate damage.
• JFET has a higher gate current than the MOSFET.
• MOSFET can work in two modes, depletion-mode as well as enhancement mode, on the other hand, JFET only works in depletion mode.

MOSFET vs IGBT

• IGBT is the insulated Gate Bipolar Transistor meanwhile MOSFET is the metal oxide semiconductor field-effect transistor
• IGBT is the combination of the bipolar junction transistor with the MOSFET, meanwhile, the MOSFET is the true transistor.
• MOSFET are not tolerant to electrostatic discharges meanwhile an IGBT is highly stable in this regard.
• The IGBT is tolerant of overloading meanwhile a MOSFET is susceptible to damage because of overloading.
• IGBT is used in high power applications, on the parallel lines, the MOSFET has a relatively lower capacity to deal with such high power applications like IGBT.

MOSFET Review

• MOSFET is a type of FET that is a unipolar device i.e. single charge carriers are responsible for the conduction between source and drain.
• The voltage applied at the gate side is used to control the current flowing through conducting channel between source and drain.
• MOSFET is a voltage-controlled device, unlike BJT which is a current-controlled device.
• Practically, the gate of the MOSFET draws no current. However, a small amount of initial current is needed to charge the capacitance of the gate terminal.

MOSFET Applications

• MOSFET is mostly used as an electronic automatic switch in both analog & digital circuits.
• It is widely used in applications where high amplification is required.

That's all for today. Hope you have got a clear idea about MOSFET. If you have any questions you can ask me in the comment section below. I'll try my best to resolve your query as soon as possible. Your feedback and suggestion will be highly appreciated. It will allow us to give you quality work based on your needs and expectations. Stay tuned!  

Introduction to 1n4733a

Hey Fellas! I hope you are enjoying your life with love, care and passion. Today I'm going to give you the details on the Introduction to 1n4733a. It is a Zener Diode which works similar to normal diode with only exception, it can also conduct in reverse biased condition. Zener diodes are considered as a basic building components for many electronic circuits. I will try my best to give you the details on almost every feature of this zener diode so you don't need to go anywhere for finding the information regarding this zener diode. Let's get started.

Introduction to 1n4733a

• 1n4733a is a normal p-n junction diode which allows the current to flow in both directions i.e. forward direction and reverse direction.
• In other words, it conducts in both ways i.e. when it is forward biased, also when it is reverse biased.
• In order to conduct in reverse biased condition, reverse breakdown voltage must be achieved.
• Over a wide range of voltages, voltage drop across the zener diode doesn't change which makes it ideal for using for voltage regulation purpose.
• Unlike normal diodes, zener diodes work in breakdown region and are best for generating reference voltage.

• This zener diode comes with a highly doped p-n junction and sealed glass package that gives solid protection in all common atmospheric conditions.
• It is widely used to prevent the electronic circuits from over voltage.
• 1n4733a comes with different voltage rating ranging from 3.3 V to 91 V.
• It offers double slug construction which is corrosion resistant. And the leads that come with this zener diode are easily solderable and can withstand the maximum temperature up to 230 C.
• It encompasses excellent working characteristics and have power of 1 W.  The voltage tolerance appears to be 5%.

Working of 1n4733a

• Working principle of this zener diode is similar to common diode with slight difference.
• Zener diode In4733a acts like a normal diode in forward biased condition.
• It exhibits a turn on voltage that ranges between 0.3 to 0.7 V.
• It only conducts in the reverse direction when reverse voltage reaches to the breakdown voltage, allowing the current to flow from cathode to anode.
• Current reaches to maximum and stabilizes itself after a certain amount of time over a wide range of applied voltage which makes it suitable for using as a voltage stabilizer.
• Voltage breakdown occurs due to the Zener breakdown effect. It may also occur due to impact ionization. Both mechanism occur at 5.5 V., encompass same feature and don't need different circuitry in order to work perfectly. However, temperature coefficient of both mechanisms is different. Zener effect shows negative temperature coefficient and impact ionization shows postitive temperature coefficient. Both effects cancel each other at 5.5 V, making the zener diode achieve the most stable state over a wide range of temperatures.

Zener 1n4733a used for different Purposes

Zener diodes have a wide range of application specially when it comes to voltage regulation. This zener diode comes with many specifications and applied to electrical circuits in different forms as follow.

As a Voltage Regulator

• Zener diodes are useful to regulate the voltage in many small circuits. When zener diode is connected in parallel with the voltage in reverse biased mode, it will start conduction when voltage equals to a breakdown voltage.

• In the above figure, source voltage is applied in parallel with the diode. It will perfectly decrease the output voltage from its input, while keeping the breakdown voltage constant over a wide range of source voltage. Output voltage will remain stable, even the fluctuation in source input voltage won't effect the output voltage due to constant breakdown voltage.

Waveform Clipper

• Zener diodes are also used as a wavefrom clipper when they are connected in series. Following is the figure of two zener diodes connected in series.

• When zener are connected in series, it allows the waveform to clip from both ends of the cycle i.e. positive end of the cycle and also negative end of the cycle.
• Zener diodes connected in series also prevent the high voltage spikes at the end of the output signal, allowing the reshaping of output voltage.

Voltage Shifter

• Zener diode can also use for shifting the output voltage.
• When it applies as a voltage shifter, it drops down the output voltage by the quantity equal to breakdown voltage.

That's all for today. I hope you have now got a clear idea about working principle of 1n4733a and how it is used for different purposes. However, if you have any confusion, you can ping me a message in the comment section below, I'll be glad to help you in this regard. Your feedback and suggestions will be highly appreciated. Brace yourself for next article. Stay Blessed!

Introduction to JFET

Hello Guys! I hope you are doing great and having fun. I am back to give you a daily dose of knowledge that will enhance your learning skills and put you ahead of others. Today, I am going to give you details on the Introduction to JFET. It is a Junction Field Effect Transistor that consists of three terminals named drain, source and gate. It comes in two configurations called the P-Type channel and the N-Type channel. I'll give you brief details on JFET and try to cover as many aspects as possible. Let's get started:

Introduction to JFET

• JFET (Junction Field Effect Transistor) is a uni-polar voltage-controlled device that consists of three terminals called drain, source and gate.
• Unlike bipolar junction transistors which are bipolar current-controlled devices in which a small amount of base current is used to control a large amount of current at the collector and emitter side, JFET is a uni-polar voltage-controlled device in which voltage applied to the gate terminal allows the current to flow through JFET, resulting in input applied voltage equals to the current flowing through the transistor.

• In JFET, gate is always negatively biased as compared to source.
• As compared to bipolar junction transistors, JFET are uni-polar because current carriers in case of JFET are either electrons or holes while bipolar junction transistors are operated by the movement of both electrons and holes.
• The operation of JFET depends on the electric field created by input applied voltage, hence it is called Field Effect Transistor.

• JFET can be classified into two types on the bases of their operation i.e. N-Type and P-Type JFET.
• In JFET, current carrying path between drain and source is called channel which contains no pn-junction. Channel can be made up of P-Type or N-Type semiconductor.
• Current flowing through this channel widely depends on the input voltage applied to the gate terminal of JFET.
• Field effect transistors generally comes in two types JFET (Junction Field Effect Transistors) and MOSFET( Metal Oxide Semiconductor Field Effect Transistors)
• As stated earlier, JFET contains no pn-junction, instead it comes with channel that consists of N type or P type semiconductor that passes between source and drain terminals of JFET.

JFETs are classified into two main configurations.

1. N-Type Configuration
2. P-Type Configuration

1: N-Type Configuration

• In N-Type configuration current flowing through the channel is negative i.e. current flow is carried out by the flow of electrons which are also termed as donor impurities.

• The measure of conductivity of electron in N-Type configuration is much higher than the holes in P-Type configuration, because electrons come with high level of mobility than holes. Hence, in terms of conductivity, N-Type configuration is more efficient than P-Type configuration.
• Channel is a conducting path between drain and source. Within this channel, there lies a third terminal called Gate at which input voltage is applied that is used to control the current flowing through the JFET.
• As channel is resistive in nature, resulting in creating the voltage gradient which becomes less positive as we move from drain to source terminal. This less positive voltage makes drain terminal high reverse biased and source terminal low reverse biased. This bias creates a depletion region whose width is directly proportional to the bias itself.
• The current carrying path between source and drain is controlled by the voltage applied to the gate terminal. In an N-Type configuration of JFET this gate voltage is negative while in case of P-Type configuration it is positive.
• It is important to note that gate current in reverse biased condition in the JEFT is practically zero, while base current in Bipolar junction transistor always comes with a value greater than zero.

N-Type Channel Biasing

• Following is the figure shows N-Type semiconductor with P-Type material which forms the reverse biased PN-junction that creates a depletion region around the gate terminal of JFET.

• Depletion region will be created in the absence of external voltages. JFET are also termed as depletion mode components.
• The depletion region will create a voltage gradient of some thickness which ultimately limits the flow of current, hence results in increasing the overall resistance of FET.
• It is clear from the figure above that most part of depletion region lies between the gate and drain terminals which least part lies between the gate and source terminals which means resistance between gate and drain terminal appears more than the resistance between gate and source terminals.
• In the absence of external input voltage at gate and small voltage at the drain and source Vds allows the saturation current to flow between drain and source.
• The amount of current flowing through the pn-junction will be restricted by the depletion region around the pn-junction.
• It is important to note, if we apply negative voltage at the gate and source Vgs terminals, it will cause the depletion region to grow which ultimately restricts the flow of current, hence results in decreasing the overall conduction of transistor.
• If the voltage applied at the gate terminal Vgs appears to be more negative, it will allow the depletion region to increase and results in decreasing the overall width of channel. The moment comes when applied voltage at gate terminal appears to be negative to the point that will squeeze the channel and won't allow a fraction of current to flow between source and drain terminals.
• The negative voltage applied to the gate terminal at which no current flows between drain and source terminals is called "Pinch-off Voltage".
• In pinch off region negative voltage at the gate terminal Vgs controls the overall conductivity of the channel. This is the reason JFET are called voltage controlled devices.
• Voltage appears at the gate terminal must not be positive, otherwise it will make resistance zero and allows the current to flow between gate terminal instead of source terminal. Positive voltage at the base terminal can damage the transistor at large.

2: P-Type Configuration:

• In P-Type configuration current flowing through the channel is positive i.e. current flow is carried out by the flow of holes which are also termed as acceptor impurities. Both N-Type and P-Type configurations come with same characteristics with some exceptions.

1. Current carriers in N-Type configuration are electorn, hence current appears to be negative
2. Current carriers in P-Type configuration are holes, hence current appears to be positive.
3. Biasing voltage in P-Type configuration comes with reverse polarity.

• The voltage applied at the gate terminal is used to control the current flowing between source and drain. As JFET is a voltage controlled device and no current flows through gate terminals Ig=0. Hence in that case, current flowing out from source terminal will be equal to the current flowing into the drain terminal i.e. Is=Id

 

V * I Curves of N-Channel JFET

Following figure depicts the four region of operation of JFET.  

• Ohmic Region: Region is called ohmic region when Vgs=0. In this region JFET operates like a voltage controlled resistor.
• Pinch off  or Cut-off Region: It is region at which voltage applied to the gate is negative to the point which causes depletion region to increase and allows the current carrying width to decrease till it disappears, resulting in maximum resistance to appear and current flowing through the channel will be zero.
• Active or Saturation Region: The region that is controlled by gate voltage Vgs and where JFET becomes good conductor is called active region. Vds has no effect on active region.
• Breakdown Region: Region is termed as breakdown region where voltage between source and drain appears to be maximum to the point where it breaks the resistive channel and allows the current to flow between the channel.

V * I Curves for P-Type JFET

• The curves for P-Type configuration appear to be same with one exception i.e. Increase in positive voltage at the gate terminal will decrease the current at the Drain terminal Id.

Formula for Drain Current and Drain-Source Channel Resistance

• Drain current at the saturation region can be calculated as follows:

Id= Idss * [ 1 - Vgs / Vp ]

• Id lies between zero to Idss.
• Similarly, if we know drain source voltage Vds and drain current Id, we can calculate the drain-source channel resistance.

Rds = ?Vds / ? I d = 1 / gm

• Here gm represents the "transconductance gain"

Different Modes of Operation of FETs:

FETs can be classified into three different modes of configuration.

1. Common Source Configuration
2. Common Gate Configuration
3. Common Drain Configuration

1: Common Source Configuration CS:

Common source configuration is an analogous to the common emitter configuration in the bipolar junction transistors. In this configuration input voltage is applied to the gate terminal and output we get is from the drain terminal. This mode of operation comes with amplified voltage and high impedance, hence it is mostly used in high audio frequency amplifies. As this is an amplifying circuit, it allows the output to be diverted 180º from its input.

2: Common Gate Configuration CG:

Common gate configuration is an analogous to the common base configuration in the bipolar junction transistors. In this configuration input voltage is applied to the source terminal and output appears at the drain terminal while gate is connected to ground. In this configuration impedance will be low as compared to common source configuration. This configuration is mostly used in high frequency and impedance matching circuits. Unlike common source configuration, here "output signal is in phase with the input signal"

3: Common Drain Configuration CD:

Common drain configuration is an analogous to the common collector configuration in the bipolar junction transistors. In this configuration input voltage is applied to the gate and output signal is collected from the source. It is important to note there is no signal applied to the drain terminal. Vdd simply depicts the bias voltage. Similar to common gate configuration, here "output signal is in phase with the input signal"

Comparison between BJT and JFET

• • Both, bipolar junction transistors and uni-polar field effect transistors encompass same characteristics with some exceptions.
  • BJT are bipolar devices i.e. they are operated by the movement of both electrons and holes. JFET are unipolar devices i.e. they are operated by the movement of either electrons or holes.

• As compared to Bipolar junction transistors, JFET comes in much smaller form and can be used in many tiny electronic chips.
• One major feature that differentiates between bipolar junction transistors and JFET is the input impedence. It is very high in case of JFET while it appears very low in bipolar junction transistors.

Applications

• JFET are widely used in many electronic appliations. They are mainly used for amplification purpose.
• JFET are used to obtain high frequency audio signal.
• They are useful for obtaining impedance matching circuits.

That's all for today. I hope you have got a clear idea about JFET. However, if still you feel any doubt or query in understanding the concept of JFET, you can ask me in the comment section below. I'll be glad to help you in this regard. Your feedback and suggestion will be highly appreciated. It will help us give you quality work that resonates with your needs and expectations. Stay tuned!

Introduction to CBR Testing

The California bearing ratio (CBR) testing is an evaluation of the strength of a ground, base courses, and substrates. The measure was invented by the California Department of Transport has been a vital part of construction, especially the construction of roads and airstrips. A site test is done to establish the amount of pressure it would take to penetrate aggregate or soil using a standard plunder. This pressure value is then divided by pressure necessary to get equal penetration for the pressure to go through standard crushed rocks. When CBR testing was developed, the objective was to help in the measurement of load bearing capacity of materials like soil that were used in the construction of roads. It could also be useful in estimating the load bearing capacity of soils beneath paved airstrips or even unimproved airstrips. Basically, the harder a surface becomes, the higher the rating. The test is useful as it helps to determine the thickness of material needed to make a proposed road strong enough to withstand the heaviest vehicle that could use the road.

Procedure of Performing a CBR Test

The procedure required while performing a CBR test includes measuring the pressure needed for a soil sample to be penetrated while using a standard plunder. Harder surfaces will read a higher CBR value and normally, 2% is achieved on clay while some sands could read up to 10%. A sub-base that is of good quality will have a CBR rating between 80 and 100%, and this means such a material or surface is compact and strong enough to withstand a lot of weight. It is the reason while constructing roads this is put into consideration to ensure the soils and materials sourced match the rating of that particular road. A road that should be used by heavy trucks might require a different kind of material from that designated for cycling.

Particle Size

Something else about CBR testing that you should understand is that it is only possible for materials that have particle size of 20mm. Materials with larger particles than this will usually be subjected to the Plate Bearing Test. The technique used involves using a cylindrical plunder (about 50mm), which is driven into the ground. A four-wheel vehicle is used to provide reaction load and add the force needed to drive the plunder into the material. Most tests are done up to depths ranging from 500 to 1000mm across 20-30m intervals along the centreline of the construction. It is recommended to have at least three tests for each site to get the best values and to be sure the findings arrived at reflect the truth. Some operators do up to 10 tests in one day and provisional results are provided on the site.

Dynamic Cone Penetrometer CBR Test

CBR tests are also performed using portable hand-held equipment. Different companies use hand held equipment while assessing CBR value and this value is calculated as a value of an empirical test performed on the soil to determine if it is fit to be used for road construction. Such equipment give a continuous record that highlights penetration resistance on each layer with a depth of one meter from the surface.

Impact of CBR in Saturated Clays

Apart from working with dry soils, some areas have wet clay and before a project commences it is always necessary to have measures of the CBR rating of the soil so as to inform on the best material to choose for paving. Several analyses have been done to show how the test performs in clay. The focus was to review if the test would reflect the stiffness of the soil. Most of the findings showed that CBR shares no consistent correlation with stiffness or strength and thus the recommendations made were to encourage the use of full load penetration together with CBR so as to understand which type of capping layer or subgrade material would be ideal.

Flexible Pavement Design

This is a method applied to help determine the required thickness of a pavement. It relies on two methods for the design using CBR value. The methods are CBR procedure recommended by the state and the CBR method that is recommended by IRC.

Data Required

For flexible pavement design, you need a few variables including:

• The CBR value of soil subgrade
• Base course CBR value
• Sub base course CBR value
• Wheel load (KN or KG)

The wheel load used is picked from one of the three groups available, which are based on traffic conditions and recommendations. 1. For light traffic - 3175 KG 2. For medium traffic – 4082 KG 3. For heavy traffic – 5443 KG

Calculating Thickness

With the values mentioned above, it is now possible to calculate the pavement thickness required. You need the total thickness (T) and the value of the sub base course T(sb). With the two values, you can calculate the recommended thickness of the sub base course (Tsb), which is gotten with the following simple calculation.

Tsb = T – T(sb)

What are the Advantages of CBR Testing?

There are many advantages of CBR testing that make it a necessary procedure to perform before you undertake any construction project that includes building a pavement or road. Here are few you might want to keep in mind.

• No technical experience is required, so the test could be done by anyone with basic skills.
• You can use portable equipment to get the values and this does not require many resources.
• It is applicable to many materials besides working with subgrades.
• You could do testing on samples that act as representatives of water conditions for the future.
• CBR tests are known to adapt to pavement design better than any other method available out there. It is faster and you are able to get more accurate results.

There are many other methods available that could help in measuring the load bearing capacity of a material, but CBR has proved over time to be more reliable. You could get different results while using different methods, but CBR gives a more reliable range of estimation.

Introduction to BF259

Hello Friends! I am back again to fill your appetite with more knowledge and skills. Today, I am going to explain the details on the Introduction to BF259. It is a bipolar NPN (negative-positive-negative) silicon transistors which comes in metal casing. It consists of one P layer that lies between the two layers of N doped semiconductor. I am going to cover all aspects related to this bipolar transistor. Let's get started and have a look, how it works and what are the applications it finds useful.

Introduction to BF259

• BF259 is a bipolar silicon transistor which is made up of two N doped layer and one P doped layer.
• It is mainly a three terminal device which consists of emitter base and collector.
• P terminal of the transistor acts like a base while other two sides of P layers act as emitter and collector respectively.
• Small current at the base is used to control a large amount of current at the collector and emitter side.
• The power it can dissipate is 1 W, while transition frequency is about 75 MHZ.
• DC collector current is 100mA.
• Maximum power dissipation across collector is 0.5 W.
• BF259 is also considered as a current operated device.

• Maximum collector base voltage is 300 V and is denoted by Vcb.
• Maximum collector emitter voltage is 300 V and is denoted by Vce.
• It comes with lots of major applications but mainly it is used for switching and amplification purpose.

1. BF259 Pinout

BF259 NPN silicon transistor consists of three terminals. 1: Emitter 2: Base 3: Collector Actual pinout of this NPN transistor is given in the figure below

• The base current is used to control the large amount of current on the collector and emitter side.
• The way the base current impact the emitter and collector current is used for the amplification applications.
• This bipolar transistor will turn ON when current flows from emitter and collector.

2. Mechanical Outline of BF259

The mechanical outline of bipolar silicon transistor BF259 is shown in the figure below:

• All the dimension are given in mm.
• You must take these dimension into consideration before you plan to make a circuit so these dimension properly fit in the circuit.

3. Circuit Diagram of BF259

The circuit symbol of BF259 is shown in the figure below:

• This NPN silicon transistor comes with a positive base side and negative emitter side.
• Emitter current is the sum of base and collector current.
• Small amount of current at the base side is used to handle the large amount of current at the emitter and collector side.
• Main difference between NPN and PNP transistor is, Current will sink into the base side in case of PNP transistor while current from the base side will source to the transistor in case of NPN transistor.
• Transistor current can be found by dividing the collector current to the base current. It is also called beta current and is denoted by ß. Beta has no units as it is a ratio between two currents.
• Value of beta is used for the amplification purpose. Beta value ranges between 20 to 1000, however, its standard value is 200.
• The ratio between collector current to the emitter current is called current gain of the transistor and is denoted by alpha a.
• The value of alpha ranges between 0.95 to 0.99, however, in most of the cases it is considered as 1.

4. Absolute Maximum Rating BF259

The maximum absolute rating of BF259 is shown in the figure below.

• Units of current and voltage are mA and V receptively.
• These rating are important for many engineering projects.

5. Applications

• BF259 is also called high voltage video amplifier and is mostly used for high voltage video output.
• It is also used for the audio output stages.
• These transistors are the main drivers for horizontal deflection circuits.

That's all for today. If you have any question you can easily ask in the comment section below. I'll try my best to help you solve your queries. Your suggestion and feedback will be highly appreciated. Stay tuned for next article.

Introduction to 2n4402

Hey guys! I aspire you a prosperous life filled with joy and happiness. Today, I am going to uncover the details on the Introduction to 2n4402. It is basically a PNP (Positive-Negative-Positive) silicon transistor where N doped layer lies between the two P doped layer. It consists of three terminals i.e. emitter, base, collector. Here N represents the base of the transistor and two P layers represents the emitter and collector respectively. I'm going to cover all aspects related to this transistor. Let's hop on the board and dive in the details of this silicon transistor.

Introduction to 2n4402

• 2n4402 is a bipolar silicon transistor, where one layer of N doped semiconductor is sand-witched between the two layers of P doped semiconductor.
• It works in a way, the small current at the end of the base is used to control a large amount of current at the end of collector and emitter.

• PNP transistor works in a similar way to NPN transistor with the exception of current carriers. In case of NPN transistors, current carriers are electron while current carriers in the case of PNP transistors are holes and direction of current and polarities of voltage will be reversed in this case.
• In PNP transistor, P letter represents the polarity of voltage applied to the emitter which is positive and N letter shows the polarity of voltage applied to the base which is negative. In order to conduct in PNP transistor, Emitter will always be more positive than base and collector.

2n4402 Pinout

2n4402 consists of three pins

• 1: Emitter
• 2: Base
• 3: Collector

 

• Unlike NPN transistors, here current flows from emitter to collector and current carriers are holes.

PNP Circuit Symbol

• Following is the circuit symbol of PNP transistor. It consists of two P layers and one N layer.

 

• The polarity at the emitter side is positive with respect to both base and collector.
• The base of this transistor is negative with respect to emitter.
• Current flowing through the emitter side is the sum of current flowing through collector and base.
• Small amount of current at the base side is used to control the large amount of current at the collector and emitter side.
• PNP and NPN works in similar way with the exception of current direction and medium used for the flow of current.
• In PNP transistor current flows from emitter to collector and current carriers in this case are holes which are collected by the collector.

PNP Transistor Configuration

• Transistor configuration of PNP 2n4402 transistor is shown in the figure below:

• Emitter is positive with respect to collector and base
• Small amount of base current is used to control the large current at the collector and emitter side.
• Current carriers are holes which are collected by the collector.

Transistors as a Matched Switch

• In most of the cases, PNP transistors replace the NPN transistor with the only exception in the direction of current and polarities of voltages.
• Like NPN transistor, PNP transistor can also be used as a switching device.
• You might think what is the point of using PNP transistor while there are lots of NPN transistors out there that can be used as a switch or for amplification purpose. However, taking two types of transistors come with a lot of advantage in designing the power amplifier circuit.
• Class B-amplifiers come with a two pair of NPN and PNP transistor, where both transistors are used to control the current flowing in both directions at any instant of time. Transistors are called "Complementary Transistors" which use both NPN and PNP transistor of identical characteristics.
• In Class B-amplifiers, both transistors work in a similar way i.e. NPN transistors conducts for the positive half cycle and PNP transistor conducts for the negative half cycle of the transistor. This results in flowing the power at the load out put in both directions. PNP transistors will switch on when it sinks current to its base side and it will switch off when current at the base side stops to flow.

Applications of 2n4402

• These transistors are mainly used for voltage and power amplification.
• In combination with NPN transisters, these PNP transistors form a perfect bond through which current flows alternately from both sides of NPN and PNP transistors.

That's all for today. I hope you'd enjoyed our article. If you have any query or question you can easily ask in the comment section below. I'd be glad to help you in this regard. Your suggestion and feedback will be highly appreciated. Stay tuned for next article.

Introduction to Resistors

Hey guys! I hope you are doing good and having fun. Today, I am going to unlock the details on the Introduction to Resistors. Resistor is a two terminal component that is used to restrict the flow of current. Resistors are widely used in electrical circuits. They come in different forms ranging from variable resistors to fixed resistors. Depending on the feature of resistors, both are used in many applications. I am going to cover all aspects relating to resistors. Let's get started.

Introduction to Resistors

• A resistor is a two-terminal device that is used to resist the flow of current. It is one of the most commonly used components in electrical circuits.
• Resistance of any resister is described in ohms. Ohm is denoted by the Greek letter omega. Each resister has a different value of resistance which tells us how strongly it resists the flow of current. More the value of resistance more is the capability of resisting the current.
• Resistance will be considered as one ohm if the potential difference between the two ends of the conductor is 1 V and a current flowing through it is 1 Ampere.
• Resistance can be derived from Ohm's law which indicates voltage is directly proportional to the current flowing through the conductor.

V= I * R

• Each resistor comes with two wires, also called as leads. Between these two leads there lies a ceramic part which actually resists the flow of current. Resistor consists of three colored strips that indicate the value of resistance.
• Some resistors come with four colored strips. In such case, fourth strip indicates the value of tolerance. Tolerance is the value of the deviation of resistance from its given value on the resistor. Gold color of forth strip indicates tolerance is 5% and silver color indicates tolerance is 10%. Where there is no forth strip, tolerance is considered as 20%. Suppose, if resistance has 50-ohm resistance with no forth strip. Then tolerance of such resistor can be 50 ±20%.
• Resistance of any resistor also depends on its resistivity, its length and cross-sectional area.

• Resistors also indicate temperature coefficient. Temperature coefficient is known as a resistance due to the change in temperature. There are two types of temperature coefficients. Positive temperature coefficient and negative temperature coefficient. If resistance increases with the increase in temperature then it is called positive temperature coefficient and if resistance decreases with the decrease in temperature then it is called negative temperature coefficient.

How to Limit Current using Resistance

• Main purpose of resistance is to limit the current flowing through the component.
• Suppose, if we want to connect the LED with the direct DC source i.e. Battery, then it will burn out right away the moment you connect the LED with the battery.
• Because battery will allow a large amount of current to flow through the LED which will burn it out.
• LED can be avoided from any severe damage if we put the resistor between the battery and LED. It will control the amount of current flowing through the LED.
• Value of resistance you use depends on the current rating of the battery. You need to use the resistor with high resistance if current rating of a battery is high.
• We can calculate the resistance by using Ohm's Law. Suppose we have LED that comes with voltage rating of 12 voltage and current rating of 100mA or 0.1 A. From Ohm's Law

V=IR

R= V/I

R=12/0.1= 120 O

• In order to avoid LED from damaging we need resistor with resistance of 120 O

 

Combination of Resistors

Resistors can also be used in combination. There are classified into two types according to their combination.

Resistors in Parallel

• If resistors are connected parallel to each other, then total resistance will be equal to the sum of reciprocal of all resistance.

1/R= 1/R1+1/R2+1/R3............1/Rn

Resistors in Series

• If resistors are connected in series, the total resistance will be equal to the sum of all resistance.

R= R1+R2+R3+R4..........Rn

Power Dissipation

• The power consumed by any resistor at any moment is defined as
• P= VI= V(V/R)= V²/R
• Most of the resistors are classified on their ability of power dissipation. Resistors who dissipate a large amount of energy are called as power resistors and are mostly used in power supplies, power amplifiers, and power conversion circuits.
• Power resistors are physically larger than normal resistors and their value cannot be directly identified by the reading color strip method.
• Resistors pertain to severe damage if their average power dissipation is greater than thier power rating. It results in permanently alternating the resistance.
• Excessive power dissipation can also damage the whole circuit. In order to avoid burning of the circuit, flameproof resistors are used that suddenly open the circuit before power dissipation gets too high.

How to Calculate Resistance of any Resistor

There are two different ways to calculate the resistance:

Reading the Color Bands

• First method to calculate the resistance is by reading the color bands of the resistor.
• Each strip of color on the resistor represents a specific digit.
• Different colors corresponding to their digit values are given below.

• In the above figure, the first strip is brown and corresponding digit to brown is 1.
• The second strip is black, and the corresponding digit to black is 0.
• The third strip is orange and the corresponding digit to orange is three which actually shows the number of zeros.
• Forth strip is made of gold which indicates tolerance is ±5%.
• So overall resistance of this resistor is 10,000±5 % ohm.

Using a Multimeter

• Second method to measure the resistance is by using the multimeter as an ohmmeter. Mainly multimeter performs three functions. It is used to measure current voltage and resistance.
• Put the black probe on the COM port of multimeter. And put the red probe into the VOmA.
• You can measure the resistance of any resistor by holding the resistor with the two separate probes of the multimeter. Before calculating the resistance, you need to set the dial to ohm which is denoted on the multimeter by the symbol O.

 

Types of Resistors

Resistors come in different forms, sizes, and shapes. Resistors are used in different applications depending on the current rating voltage and resistance. Let's discuss resistor types and their applications. Resistors are mainly classified into two types:

1. Linear Resistors
2. Non-Linear Resistors

1. Linear Resistors

• Resistors are termed as linear resistors where current is directly proportional to the applied voltage.
• Resistance of these resistors changes with the change in temperature and voltage.
• In order words, resistors which follow Ohm's law are linear resistors.
• Linear resistors are further classified into two types
  • Fixed Resistors
  • Variable Resistors

1.1 Fixed Resistors 1.1.1 Carbon Composition Resistor

• Carbon composition resistors comprise of rigid resisting element incorporated with lead wire. The resistor body is covered with plastic or paint.
• The resistive element at the mid of the lead wires contains fine carbon and insulating material which is usually ceramic. The resistance of such resistors is measured as the ratio of ceramic to carbon.
• Resistance value widely depends on the concentration of carbon value. More is the concentration of carbon, lesser will be the resistance.
• Carbon composition resisters come with poor stability and 5% tolerance.
• These resistors are become obsolete because of their high price but still they are used in wielding controls and power supplies.
• Resistance of such resistors varies from few ohms to 22 mega-ohms.

1.1.2 Carbon Pile Resistor

• A carbon pile resistor consists of layers of carbon discs that are placed between two metal plates.
• Resistance between the plates can be changed by changing the clamping pressure.
• These resistors are widely used in radio transmitters.
• A carbon pile resistor can also be used in generators, where it adjusts the current to keep the voltage in certain state.

1.1.3 Carbon Film Resistor

• A carbon film resistor consists of amorphous carbon which provides relatively large resistance.
• These resistors encompass low noise as compared to carbon composition resistor.
• A carbon film resistor comes with a power rating that ranges between 0.125 to 5 W with resistance 1 ohm to 10 mega-ohm. These resistors are used in areas where high stability is required.

1.1.4 Thick Film Resistor

• Thick film resistors come in the shape of SMD(Surface mount device).
• Both, think and thin film resistors are manufactured in a same way but main difference is the resistive element that is used in thick film resisters is relatively very large than used in thin films.

1.1.5 Thin Film Resistor

• Thin film resistor consists of ceramic rod and resistive material.
• A very thin layer of conducting material is being placed on the insulating rod that is made of glass or ceramic material. This method of making thin film is called vacuum deposition.
• When thin film resistor is manufactured, it doesn't give an accurate value of resistance.
• Resistance value can be made accurate by the process called laser trimming.
• These resistors come in the tolerance range that lies between 1% to 5% and encompass much less noise level than thick film resistors.
• Compared to thick film resistors, thin film resistors are highly expensive.

1.1.6 Wire Wound Resistors

• Wire wound resistors are widely used in many electrical applications. They are manufactured by winding a metal wire around fibreglass core or ceramic material. Whole assembly is being formed where two ends of wire are welded with rings and are covered with high layer of molded plastic or paint.
• These resistors have capability to bear high temperature upto 450 ºC.
• As wire wound resistors are same like coil so they inherit high value of inductance as compared to other resistors.
• Both, carbon composition resistors and wire wound resistors are used in same application except where high frequency is required. High frequency response of carbon composition resistors is better than wire wound resistors.

1.2 Variable Resistors

• Resistors are termed as variable resistors whose values can be adjusted manually by screw, knob, or dial.
• These resistors come with sliding arm that is attached to the shaft.
• Resistance value can be changed by rotating the sliding arm.
• They are mainly divided into two types:
  • Rheostats
  • Potentiometer

1.2.1 Rheostats

• Rheostat resistors are also known as variable wound resistors or tapped resistors.
• Rheostat is a manual operated three terminal device which is mainly used to restrict the current value.
• In order to make rheostat, Nichrome resistance is being wound around a ceramic core, then they are placed in a covered shell.

  1.2.2 Potentiometer

• A potentiometer is a three terminal device that consists of tapping points that are adjusted by a rotation of shaft.
• It can be used to provide a potential difference between the two terminal connected to the tapping points.
• They are widely used for volume control in many radio receivers.
• Potentially there is no difference between rheostat and potentiometer, however, both are used for difference purpose.
• Rheostat is used for controlling the level of current in the circuit while potentiometer is used for controlling the voltage in the circuit.

 

2. Non-Linear Resistors

• Resistors are termed as non-linear resistors where they do not pertain to follow ohm's law but their value of resistances changes with the slight change in temperature or current.
• Non-linear resistors are further divided into two types:
  • Thermisters
  • Varisters

2.1 Thermisters

• Resisters are termed as thermisters, if current flowing through it changes with the change in temperature.
• Thermister is basically a two terminal device which uses variable resister and indicates even a slight change in temperature.
• In thermister, resistance and temperature are inversely proportional to each other.

2.2 Varisters

• Resisters are termed as varisters if current flowing through it changes with the change in applied voltage.
• These resistors are sensitive to voltage and avoid the circuits from getting high voltage spikes.
• They are used to maintain the voltage to a required level.

Applications of Resistors

Resisters are widely used in many electrical circuits. Following are the main applications of resistors.

• They are used to limit current in order to avoid short circuit
• They are used to control voltage in order to avoid high spikes at the end of out put voltage
• Used in many electronic industries
• Temperature can also be controlled using these resistors
• In home electronic appliances like heater and iron

That's all for today. I have tried my best to cover as many aspects as possible relating to resistors. However, if still you feel any doubt or query in understanding the concept of resistors, you can always ask me in the comment section below. I'll be glad to help you in this regard. Thanks for reading the article. Give your feedback, how do you like our articles what are the suggestions you would like to give that can help in crafting the articles in better way? Stay tuned for next article! Have a blessed day ahead!