Create Web Server with ESP8266

Hello friends, I hope you all are doing great. Today, we will create a web server with ESP8266 microcontroller to control the activation of an LED. The goal is to understand how the ESP8266 connects to a WiFi network, how it sets up a web server, and how it is possible to exchange information between the browser and the esp8266.

Where To Buy?
No.	Components	Distributor	Link To Buy
1	ESP8266	Amazon	Buy Now

Components Required

• 1x Computer/notebook with Arduino
• 1x Mini-USB cable.
• 1x NodeMCU (ESP8266 Breakout Board)
• Internet Browser (Chrome, Firefox, IE…)

ESP8266 Libraries for Arduino IDE

For this project, we will use two libraries:

• ESP8266WiFi: This library carries all the functions necessary for the ESP8266 to connect to a wifi network.
• ESPAsyncWebServer: This library carries the functions needed to create and manage an EB server.

Creating the code

• We can divide the code into three main functionalities:
  1. Control the LED.
  2. Connect to Wifi
  3. Create the webserver.

And we'll treat this building in blocks.

Importing Libraries

• The Libraries must be included at the beginning of the sketch so that their functions are already available elsewhere in the code.

LED Control with ESP8266

• Our first step is to define the pin to be used. For our example, we will use the LED of the NodeMCU module.

• And set this pin as output in the setup function.

• We will also create a variable to monitor LED status. This variable is not used to control the LED, but it will be important for the webserver so, we will include it here.

• So, we'll create a function that, whenever triggered, will change the state of the LED (and the variable).

• The toggleLed() function makes a function nesting in its first line:
• The digitalWrite() function receives as a value for writing, the inverse of the reading of the pin itself. So each time the function is called, it reads the current value of the pin and toggles its value.
• The following conditional is only used to update the stateValue variable. To test the function, you can include it in the loop as follows:
• With these inclusions, we will have this code:

• With this code, the NodeMCU module LED, we expect to change state every 3 seconds. Remember to remove the data inside the loop function when you finish the test. We will not use them in the next steps.

Connect ESP8266 to WIFI

• Now let's connect the ESP8266 to your WIFI network. We'll start by creating a variable to store the network name and another one for the password.

• The connection could be executed directly in the setup function, but we will create a standalone function to make the code more organized and so that it can be reused if you want to create a reconnect function.

The wifiConnect() function will send a connection request and wait for it to be approved.

With Wifi.begin(), ESP8266 will search the network informed in the ssid variable and send a connection request, informing the password (just like what a cell phone would do).

The WiFi.status() function can return the following values:

• WL_CONNECTED: assigned when connected to a WiFi network;
• WL_NO_SHIELD: assigned when no WiFi shield is present;
• WL_IDLE_STATUS: it is a temporary status assigned when WiFi.begin() is called and remains active until the number of attempts expires (resulting in WL_CONNECT_FAILED) or a connection is established (resulting in WL_CONNECTED);
• WL_NO_SSID_AVAIL: assigned when no SSID are available;
• WL_SCAN_COMPLETED: assigned when the scan networks is completed;
• WL_CONNECT_FAILED: assigned when the connection fails for all the attempts;
• WL_CONNECTION_LOST: assigned when the connection is lost;
• WL_DISCONNECTED: assigned when disconnected from a network;

In this project, we are not handling connection failures, so we are only interested in the WL_CONNECTED return. The function will wait while this is not the connection status and, when identifying it, it will look for the IP address it received on the network.

Here is a point of attention. The WIFI network must allow the connection and provide an IP by DHCP. If any device can connect to your network just by offering the password, don't worry. This configuration must already exist.

We've added some information to be viewed on the Serial monitor, so the serial needs to be initialized before we call the wifiConnect() function.

• This should be our code so far:

• The expected result on the Serial Monitor is as follows:

• From this point on, the ESP8266 can be found by network tools like the Advanced IP Scanner or a simple PING at the command prompt.

Creating the Webserver with ESP8266

• Spoiler Alert: At the end of this step, you can view our webserver at the address
• HTTP://”IP address”, for our case http://192.168.18.76.
• We will start by creating an instance of AsyncWebServer operating on port 80.

• In short, a webserver operates as a file manager that delivers on-demand. Then the browser makes a request, the web server responds and continues to wait for new requests.
• All this happens following communication protocols (HTTP, FTTP, or both), rigorous error handling, and high-security logic.
• The library takes care of preparing the backstage of the webserver, which saves us a lot of time and lines of code. But we still need to configure what happens on each request.

We will handle two requests:

• When the page starts or refreshes
• When we press the LED state change

The first will occur when we send a GET request to the root “/”. What the browser does automatically when we go to http://192.168.18.76.

• The server will respond with status 200 (default success response), the information on the type of file sent ("text/html"), the HTML file (which we will create next and save in the variable index_html), and the return of the processor( ) (which we will also create now).
• The processor function simply returns the value of the updated stateValue variable.

• The HTML file the browser expects tends to be large for a variable, and even with the good SRAM memory space the ESP8266 has, it could cause problems.
• That's why we'll use the PROGMEM utility so that the variable is written to FLASH memory.

 

• Don't worry if you don't know HTML or javascript. We won't go into details, but we'll explain the most important ones for now.
• On line 23, the page displays the value returned by the processor() function.
• In line 24, the button calls the “toggleLED()” function when activated.
• The toggleLED() function makes a GET request at address “/state” passing the toggle valceue.

• After 1 second it refreshes the page to receive the updated value. We need to handle this request:
• When the server receives the request at the address “/state” it calls the toggleLed() function
• and just replies to the server that everything went fine. And last but not least: We started the server:

• This will be our final code:

• In our browser:

Conclusion

In this project, we saw a very simple application of the power that the ESP8266 WiFi has. In the HTML file, page styling could also be included to make the page prettier.

And with that base, it's possible to expand into several cool projects. A temperature monitor via Wifi? Security systems? Home automation systems? These are just a few examples. The limit is up to your creativity.

ESP8266 based WiFi Modules for IoT Projects

The Internet of Things (IoT) and the Industry 4.0. Distinct technological revolutions but with a common goal: To integrate equipment (digital or analog) to a computer network.

And to be part of this revolution, the developer goes out of its way to include wired ethernet modules or WIFI modules in its circuits. Which increases complexity, circuit size and development cost.

What if I told you that already has a built-in WIFI microcontroller? And that it fits in the palm of your hand? For just 1 US dollar?

Today I’m going to introduce you to the ESP8266 microcontroller, from Espressif. And for those of you who already program in 8Bit microcontrollers like the Atmega328 (one of the most common on Arduino) and struggle to build your code in the modic SRAM’s 2KB and Flash memory’s 32KB… The ESP8266 offers 32KB to RAM and 512KB to Flash Memory … expandable up to 4MB.

 Did I get your attention? So, let’s go to a summary of the specs, provided by the manufacturer itself:

• 32-bit RISC architecture;
• 80MHz processor (can be expanded up to 160MHz);
• Operating Voltage of 3V;
• 32KB of RAM memory for instructions;
• 96KB of RAM memory for data;
• 64KB of ROM memory to boot;
• Flash memory preview by SPI (512KB to 4MB);
• Wireless 11 b/g/n standard;
• Operating modes: STA/AP/STA+AP;
• WEP, WPA, TKIP, AES security;
• Built-in TCP/IP protocol;
• QFN encapsulation with 32 pins;
• Main Peripherals: UART, GPIO, I2C, I2S, SDIO, PWM, ADC and SPI;
• Architecture with prediction of operation in energy saving

At this point you may have noticed that I stated that the ESP8266 has a 512KB Flash memory, extendable up to 4MB, but then I said that the module only provides this memory per SPI. Before explaining this, I want to draw your attention to another important point: The ESP8266 has a WIFI module inside a QFN package. WIFI is radio frequency! And how does it work without an antenna? The answer is: It doesn’t work!

The ESP8266Ex chip (this is its full name) needs an antenna to be connected to your antenna’s specific pins as well as a FLASH memory IC.

Started to get complicated? Don’t worry. With the idea of making the chip more accessible, several modules were developed that already include an antenna and a memory chip.

Understanding the need to include an antenna for the WIFI, a memory IC in the SPI and making pins more accessible, several manufacturers started working on ore “friendly” ESP8266’s versions. Among the best known are the ESP-01, ESP-03, ESP-05, ESP-07, ESP-12E, ESP-12F and NodeMCU. All of them have the esp8266 microcontroller in common, but they vary in size, antenna availability, memory size and pin availability. There are others, but today we’ll talk a little about them.

Where To Buy?
No.	Components	Distributor	Link To Buy
1	ESP8266	Amazon	Buy Now

ESP-01

It is the most common module in the ESP8266 range. It is compact (24.8 x 14.3 mm), the WIFI antenna is built in the board itself and has two GPIO pins that can be controlled according to programming. There are two significant drawbacks to this card:

• The pins are not intended for connection to a breadboard. Although they fit well, they end up shorting So, they necessarily need wires to extend the pins.
• The two available GPIOs play an important role in the board So it is necessary to pay attention to the level (high/low) when the board is initialized, or the board may mistakenly enter in programming mode. So, pins are safer operating as Outputs than as Inputs.

ESP-03

 

This version comes with a ceramic antenna, 7 GPIOs (two are those of the ESP-01 that require attention), a pair for UART, in size 17.4 x 12.2 mm. Smaller than 01? Yes! But that comes at a price: The encapsulation is another.

ESP-05

• No GPIOs available, it actually doesn’t even have a built-in antenna.
• This version was thought to incorporate WIFI to some other microcontroller (with the smallest possible size: 14.2 x 14.2 mm), so it has an external connector and UART pins to be manipulated by AT commands.

ESP-07

• The ESP-07 has both a ceramic antenna and an external connector. Looks a lot like the ESP-03, but leaves the meager analog pin available.
• In addition to incorporating a metallic cover that protects the circuit against magnetic interference.

ESP-12E and ESP-12F

Built-in antenna, 11 GPIOs, UART available, SPI available (not exactly, it’s still being used by the flash memory CI, but now you get the option to disable the memory and associate a larger one), an ADC pin (pause here to explain because it’s not that useful, The board operates with 3.3V, but the ADC is 0 – 1V. Low resolution, plus the big risk of damaging everything.).

The ESP-12E would be icing on the cake for the ESP8266’s boards, but the ESP-12F version handled an improvement in the antenna design and a little more pin protection.

NodeMCU

The NodeMCU module is to the ESP-12s as the Arduino UNO is to ATMEGA328s. A board with a protoboard compatible pinbus, all ESP-12 pins available, a 3.3V regulator to power the module (the VIN pin can receive 5V) and a UART – USB interface that turn the nodeMCU into a plug an play module.

There are versions with the ESP-12E (increasingly rare) and with the ESP-12F.

Now that we know a little more about the hardware, let’s take a look at how to program it.

There are different ways to programming the ESP8266. Different methods, different languages, among the most common, we have the ESP-IDF (manufacturer’s official. C programming) and others recommended, also, by the manufacturer: NodeMCU (Lua Script), Arduino (C++), MicroPython (you get one candy if you guess the language). It is possible to work with it in PlatformIO as well.

ESP-IDF

The ESP-IDF is the official Espressif solution. The SDK has a number of precompiled libraries and works with the Xtensa GCC compiler.

For a long time, the company has released RTOS and NON-OS versions in parallel. But since 2020 no NON-OS versions have been released (except minor bug fixes). Other modules from Espressif were born exclusive to RTOS versions, probably this was already part of the decision to bury the NON-OS. IN 2019, the company released a note stating that it would keep the main version, but that it would only operate in the correction of critical bugs. It even released some new features after that, but it doesn’t compare in quantity to the RTOS version.

This is without any doubt the most specialized tool that allows for the greatest customization at a low level. Drivers and libraries are customized for company modules. And specialization directly reflects on performance.

But the ESP-IDF lacks in complexity and size of the active community. Which ends up making the solution’s development a little slower. How does this happen? The programming is done in C- ANSI, in some cases with the directly treatment of registers, creating a more verbose code. More verbose? More chances for bugs. Also, active community is something that needs to be looked at when using any technology. Whether for creating new libraries or for sharing issues and solutions. The ESP-IDF user community exists, but it is much smaller than the others that will be presented here.

NodeMCU

The NodeMCU is an ambiguous term, it can either be used to indicate the NodeMCU module (hardware) or the NodeMCU development environment (software), both can be used together. But not necessarily. Let’s go to the software one.

The NodeMCU is a Lua-based firmware specific to the ESP8266 and uses a SPIFF (SPI Flash File System) based file system. This firmware is installed directly in FLASH memory, which allows the code’s execution in real time, without the need for compilation.

It offers a library structure for native functionality and for sensor’s integration, such DS18B20 or BME280, which make programming more dynamic.

The NodeMCU has been popular for quite some time. But it has three serious problems that have started to reduce its use.

• The Firmware NodeMCU, installed in FLASH, takes up a lot of Especially if the full version is included.
• It was developed based on the NON-OS version, so, firmware bugs started to get more complex to
• The memory management is quite complex in some cases. Because it didn’t compile, some memory overflow issues could only be noticed at runtime. (This was the reason I stopped using this method).

Arduino

The Arduino platform, undoubtedly the best known in the world when it comes to microcontrollers, is also on the manufacturer’s list of nominees.

The Arduino was built as software-hardware relationship that makes microcontroller’s development more accessible to non-specialists. The hardware complexity was minimal (in some cases none) and the software started to be treated in a high-level language (C++), allowing even object orientation.

Because it is so accessible, some members of the software’s community have started to be collaborators in building libraries (Only to control LCD displays, I know four), some sensor’s manufacturers offer official versions as well. Constantly updated material. Etc. Etc.

The Arduino architecture started with the Arduino Uno board (which uses an ATMEGA328), expanded support to other boards and… for some time now, it has support for ESP8266 in different modalities. There is good compatibility with standard Arduino libraries and it has its own.

MicroPython

I Don’t know the MicroPython in practice (yet), but as the name advertises, it allows programming in Python. Like NodeMcu, it deploys a firmware to FLASH memory and has well- defined libraries for hardware usage.

The space occupied in Flash is well optimized (not even compared to NodeMCU chaos). It seams to have a very active community. As for programming complexity I don’t have much information. But if you program in Python, I think it’s worth the experience.

PlatformIO

The PlatformIO is not really a development platform, but it allows an integration with other platforms to simulate the board. If you don’t have an ESP8266 on dang yet, it might be a good choice for your first steps.

However, there is a natural limitation when simulating a module whose flagship is WIFI.

Don’t you know where to start?

Personally, I think that the Arduino environment is perfect for prototyping. It’s easy to get results pretty quickly to validate a proof of concept. But in some cases you can go beyond that. If your project doesn’t demand maximum performance from the ESP8266, even the production version can be built here.

For a project that requires a lot of hardware precision, I don’t recommend intermediaries. Nothing will perform better than IDF.

For educational purposes, our next articles will use the NodeMCU board programmed on the Arduino platform.

FET: Definition, Symbol, Working, Characteristics, Types & Applications

Hello friends, I hope you all are happy, healthy and, content. We have been discussing transistors lately, from the basic definition to the types and characteristics of transistors we have covered it all. If you have a brief idea about transistors, you must be aware of the field effect transistor or you might have heard or read about it somewhere, it is one of the earliest known types of transistors which is our topic of discussion today.

Field Effect Transistors were made to cover up the lacking of previously known transistors which occupied large space and produced a lot of noise, another major problem was the low reliability of previous versions. So, let's get started with the FETs.

Definition of Field Effect Transistor

Let us define field effect transistor first,

• "The Field effect transistor is a unipolar transistor made up of semiconductor material, which uses an electric field to control the current flow."

History of Field Effect Transistors

• To know how the field effect transistors evolved throughout the ages, let us have a quick trip to history, the days when we did not have a large amount of resources to materialize our concepts.
• The first attempt to make a field-effect transistor was made by Julius Edgar in 1925, and sadly he failed miserably but he was lucky enough to get the concept patented.
• In 1934, Oscar Heil tried his luck but failed to make a successful attempt.
• In 1945, the Junction field-effect transistor was the first FET device to be constructed by Heinrich Welker.
• In successive years several attempts were made and different types of materials were introduced for making field-effect transistors and their related types. All these successful and unsuccessful attempts led to the formation of the modern-day Field Effect Transistor.

Unipolarity of Field Effect Transistor

Unipolarity of the field effect transistor means that the transistor uses either holes or electrons for working, depending on the type of material being implied for making, unlike the bipolar junction transistors which employ both the electrons and holes for their functioning.

Symbol of Field Effect transistor_ FET

• The following figure shows the symbol of a field effect transistor.
• Three terminals can be seen in the figure namely gate, source, and drain represented by D, G, and S.

• The direction of the arrowhead reflects the direction of the electric field.
• The symbol is slightly different for two different types of field-effect transistors FETs, they can either be N channel FET or P channel FET, you will learn the symbols of different FETs in their respective sections of this article.

Why Field Effect Transistors are named so, or what is the meaning of FET?

Now you must be thinking about how the field effect transistor got its name? What does it mean by a FET? There are multiple assumptions behind it, the one that I felt to be appropriate is the one that, a weak electrical signal entering through an electrode generates a larger electric field through the other parts of the transistor as well, so they are named field-effect transistors. If you know any other reason, why we call them field effect transistor other than this, you can let me know in the comment section below, I'm looking forward to your response!

BJT vs FET

A lot of times, FET is compared with the BJT let's have a brief overview of their peculiarities in this section. These are some of the significant differences between the two of them;

• BJT is a bit noisy than FET.
• BJT has a higher output impedance than FET.
• BJT is current controlled meanwhile FET is voltage controlled device.
• BJT has a lower input impedance than FET.

Working of Field Effect Transistor FET

Basic construction of a field effect transistor FET

Unlike the other types of transistors, the field effect transistors are not made up of typical collector, emitter, and base, although the number of components is the same but the name and functions of each component are entirely different. To understand the working of the field effect transistor, let us first discuss its basic components one by one.

Source

• The source is represented by the symbol S. It acts as an electrode of the field effect transistor through which the charge carriers enter the channel when voltage is applied.
• As the name suggests, the source of a field-effect transistor works as a providing source of charge carriers.

Gate

• It is represented by the letter G, wherever you see a G, immediately assume it's a field effect transistor, in the case of transistors. The conductive story of the field effect transistor begins with applying the voltage to the Gate, which is passed on to the other components.

Drain

• The drain is represented by symbol D. The drain is the electrode of the field effect transistor which provides the channel to charge carriers helping them leave the circuit.

Working of FET

• As you have a brief idea about the main components of a Field Effect Transistor and their function, we are going to discuss the working of FET.
• The current always flows from the source S towards the Drain D.
• A voltage is applied across the Gate and Source terminal which creates a conductive channel between the source S and Gate G.
• The electrons or holes flow from the source S to Drain D in the form of a stream through the channel.
• There are several other things involved in the working and function of a field effect transistor according to their types, which we are about to discuss in respective sections. So, stay tuned!
• Here arises a simple question which is often left unasked and answered too, why the field effect transistors FETs are called voltage-controlled devices?
• The FETs are called voltage-controlled devices because the current in the drain represented as ID depends on the voltage across the gate G, unlike the bipolar junction transistor which is a current-controlled device.
• The gate voltage is very important for the conduction of current towards the Drain.
• There are two phenomena that influence it one is depletion of the channel and the other is the enhanced state of the channel. Let us discuss them one by one.
• Depletion of channel: Consider an N channel FET, it has the majority of electrons as charge carriers, by making the gate more negative we would repel the electrons from the gate and these electrons would saturate the channel increasing its resistance. This makes the gate region thinner because of the minimal traffic of electrons, but the conduction channel is said to be depleted due to increased resistance.

• Again consider the n channel FET, now think yourself, what would happen when you will make the gate G of the FET is more positive? The traffic of electrons would rush towards the gate! It would make the gate region thicker due to greater traffic but on the parallel lines, the conduction channel would be enhanced due to less resistance.

Types of Field Effect Transistor

We can divide the field effect transistor into the following types based on their structure;

• Junction Field-effect transistor JFET
• Metal oxide Field Effect Transistor MOSFET

Junction Field-effect transistor JFET

• Junction field effect is one of the simplest types of field effect transistors.
• They are unipolar in function and either work with electrons and holes, the same thing which is peculiar to the simple field effect transistors.
• The junction field-effect transistor has a very high input impedance level.
• Unlike the bipolar junction field-effect transistor, it makes a little noise or is somehow silent as compared to it.
• The structure of the Junction Field-effect transistor is based on its type, in general, JFET is made up of two n-type and one p-type semiconductor material and vice versa.
• The symbol of the junction field effect transistor is as follows;

Types of JFET

There are further two types of junction field effect transistors

• N Channel Field Effect Transistors
• P Channel Field Effect Transistors

We will now discuss these two types of junction Field Effect Transistors - JFET in detail.

N Channel Field Effect Transistors

Construction of N Channel FET Let's discuss the construction of N channel Field Effect Transistor first,

• A bar of n-type semiconductor material primarily silicone is taken which acts as the substrate.
• The bar is then diffused with two p-type silicone bars which are smaller in size than the n-type silicon bar, on the two extreme ends of the substrate bar. Just imagine you are placing and gluing two small blocks on the extreme right and extreme left sides of a larger block made up of wood or any material you can stick together!
• Now we are done with diffusing the p-type materials into our n-type substrate, the leftover region conducts the current and is labeled as Channel. These channels are responsible for the conductive action of the Field Effect Transistors when voltage is applied.
• After we are done with the formation of the channel, we will now see how the main parts such as Gate, Source, and Drain are formed out of these diffused semiconductor blocks.
• The two diffused p-type silicon bars which have now formed the PN junction with the n-type material are now joined together to form the Gate.
• The two ends of the channel which was formed earlier after the diffusion process are metalized to be converted into source and drain.
• The N channel Field Effect Transistors imply electrons as the majority charge carriers. They are more efficient than the p channel junction Field Effect Transistors because electrons travel faster than the holes.

P channel junction Field Effect Transistors

Construction of P channel FET

• The same process is repeated for the construction of the p channel junction Field Effect Transistor.
• The p-type material substrate is taken in form of a large wafer or bar and then diffused with two smaller n-type bars.
• The channel formed after diffusion is then metalized at both ends to form the source and drain.
• The PN junction formed by the two n-type semiconductor materials is then connected to form the Gate.
• So this is how the p channel junction Field Effect Transistors are constructed.
• The p channel junction Field Effect Transistors imply holes as Majority charge carriers as they are unipolar.

Working of Junction Field Effect Transistor

• The Junction Field Effect Transistor always works in reverse biasing condition, that is why they have a very high input impedance.
• In the case of the Junction Field Effect Transistor, the gate current is Zero which is denoted by; IG=0
• The input voltage which is represented by VGS is the controlling factor for the output current which is represented by ID.

• You must be thinking how we control the width of the channel through which the current is conducted? The answer is simple, we alter the width of the PN junction on both sides of the channel which increases resistance to the flow of current.

As we already know that the Junction Field Effect Transistor only works in reverse biasing conditions let us now discuss a few scenarios to know how the output is generated under different circumstances.

Zero biasing condition of Junction Field Effect Transistor

• When no external voltage VGS is applied to the gate the resulting voltage to the drain would be zero which can be written as VGS = VDS = 0
• The depletion regions would have the same thickness as they had earlier because the voltage is not being applied yet.
• In this zero biased condition the drain current is produced, let me tell you how! The charge carriers in the absence of a potential difference start moving from the source to drain producing a drain current that is opposite to the conventional flow of current.
• So in the zero biased condition, only drain current exists in Junction Field Effect Transistor.

Reverse Biasing condition of Junction Field Effect Transistor

Small Reverse Voltage application scenario

• In the presence of a potential or small voltage the gate-source voltage VGS on which the Drain current ID is dependent, on applying small reverse potential width of the depletion region increases.
• Due to the increase in the width of depletion regions on both sides, the channel finds it difficult to conduct current.
• This difficulty of the channel to conduct current results in voltage drop.
• The width of the depletion region increases more towards the drain terminal, one can think of it as accidental but in science, nothing exists within reasoning and logic, the depletion region increases more towards the drain because the voltage drop is higher at the drain side.
• There is a lesser amount of Drain current ID because of the shrinkage of the conduction channel.

Large reverse voltage application scenario

• In this case we apply a higher negative voltage which is our Gate to Source voltage, represented by VGS
• The depletion regions of both the corresponding PN Junctions, keep on increasing in width.
• Eventually, both the depletion regions meet each other or you can say touch each other.
• Here is a question for you, what would happen when both the depletion regions would meet or diffuse into each other? They would eventually block the conduction of the current!
• The point at which the particular voltage blocks the conduction channel completely is called the cut-off voltage or sometimes pinch-off

MOSFET_  metal-oxide field-effect transistors.

The second type of field-effect transistors is the  MOSFET, metal-oxide field-effect transistors.

Metal-oxide field-effect transistors are one of the most common types of transistors used widely.

Features of MOSFET

• The MOSFET consumes lesser power than other transistors.
• They are exceptionally scalable and if you remember Moore's law, they are the best practical manifestation of it.
• MOSFETs have high switching speeds that is why they are used for generating pulse trains. Do you know what is a pulse train? A pulse train is the square waveform of asymmetrical waves which are periodic but non-sinusoidal in nature.
• .metal oxide field-effect transistors are considered ideal for digital circuits, analog circuits, and linear circuits as well.
• Sometimes metal-oxide field-effect transistors - MOSFETs are also called IGFET, Insulated Gate Field-Effect Transistors.

Basic Structure of MOSFET

• Let us now discuss the basic structure of metal oxide field-effect transistors MOSFET.
• The metal oxide field effect transistor MOSFET has four components, unlike the JFET.
• The components of MOSFET include Source S, drain D, body B, and Gate G.
• The gate is separated by the body of the transistor through the insulating material
• MOSFET is very similar to the JFET, but the main difference lies in the insulation of Gate Electrode from the conduction channel, either P channel or N channel, with the help of a thin layer of primarily SiO2 or Glass.
• The insulation of the Gate terminal with the metal oxide layer helps in increasing the input resistance. The insulation can increase the value of input resistance into Mega Ohms.
• For a detailed outlook on the MOSFET, its construction, working and applications you can refer to the detailed article present on our website.

Symbol of The metal oxide field effect transistor MOSFET

• The following symbol is used to represent MOSFET.

• The Arrowhead indicates the direction of current and I already know that you are aware of this!
• Now you must be thinking, why the symbolic representation is only showing three terminals, please do not search for the fourth one! Because the source is always attached to the body terminal and is represented as one terminal.
• So you can only spot the three terminals naming Gate G, Drain D, and Source S.

Types of MOSFET

Following are the four commonly known types of MOSFET;

• N-Channel Enhancement mode MOSFET
• P-Channel Enhancement mode MOSFET
• N-Channel Depletion mode MOSFET
• P-Channel Depletion mode MOSFET

Detailed outlook on all these types of MOSFET can be found in our article regarding MOSFET.

Characteristics of FET

• The Current Voltage, I-V characteristics of the Field Effect Transistor is plotted between the applied voltage VDS and Drain Current ID.
• The graph for studying the characteristic curve of a field effect transistor_ FET is plotted between the varying values of Drain Current represented by ID along the y-axis, with the varying values of VDS along the x- axis.

The graph shows the following regions;

• Ohmic Region
• Cut off region
• Saturation or Active Region
• Breakdown region

Refer to the graph for better understanding. We will now discuss each of the regions in detail.

Ohmic Region

• This is the extreme left side of the graph which represents the value of Drain Current ID when the applied voltage of the transistor between the source and gate is Zero i.e VGS= 0
• The conductive channel is small but not narrow in this case.
• Depletion regions on the corresponding sides are equal in size and haven't started expanding yet.
• Our Field effect transistor acts as a voltage controlled resistor at this instance of the IV characteristics curve.

Cut-off Region

• This is the second region of our graph represented by purple the purple lines.
• This cut-off region is also called as pinch-off region because the VGS voltage , the one which controls the current of the transistor is terribly high enough to make the circuit work as an open switch.
• At the pinch off region the conductive channel for current is almost closed due to the Increased thickness of depletion regions on both sides.

Saturation Region

• The saturation region is also called the active region of the graph.
• In this region the Field effect transistor acts a good conductor.
• The value of applied Voltage VGS, the voltage between gate and source drives the transistor.
• The Drain Source Voltage VDS has minimal effect on the current ID of the transistor at this very instant.

Breakdown Region

• This is the last and terminal region of characteristics curve for the field effect transistor, you can observe this region on the extreme right corner.
• The Voltage between the source and drain represented by VDS is very high at this point.
• The voltage is high enough that the conductive channel is broken and maximum current passes through the channel into drain.

Applications of Field Effect Transistors

• Field Effect Transistors have revolutionized the electronic world, there is an endless list of uses of field effect transistors, we are going to discuss a few important ones in this section.
• Field Effect Transistors FETs are frequently used in Integrated Circuits because of their smaller size and compactness.
• FETs are used in operational amplifiers as VRs, Voltage Variable Resistors.
• They are also used in tone controls for mixer operations on TV and on FM as well.
• Field Effect Transistors are also used in logic gates.
• Field Effect Transistors are widely used in the production of digital switches as well.

We will now discuss some of the most advanced applications of field effect transistors now,

FET as Buffer Amplifier

• First things first ,let us first discuss what does a buffer do? A buffer makes sure that the signal either digital or analog is successfully transferred to the preceding wave.
• A voltage buffer helps in amplifying the current without disturbing the actual voltage level.
• So, as you are well aware of the function of a buffer, we will discuss how a Field Effect Transistor acts a buffer amplifier.
• A buffer amplifier separates the previous stage of the signal from the next upcoming stage, drain of the Field Effect Transistor works for this purpose.
• Lastly , you must be thinking which characteristic property helps the Field Effect Transistor in achieving this, i have the answer for this question of yours! The high input impedance and low output impedance make a Field Effect Transistor an excellent buffer amplifier.

FET as Analog switch

• We have been discussing the use of Field Effect Transistors in analog and digital switches lately, we will be discussing their use in analog switches now.
• We have discussed it earlier as well in our characteristics curve and operational scenarios of the Field Effect Transistor when the output voltage equals the input voltage making the FET works as a switch.

• When the VGS which is the gate source voltage as you already know is absent, the FET works as a small resistance , although a little bit of drain current is present but its value is almost negligible.
• The mathematical expression can be written as

VOUT = {RDS/ (RD + RDS (ON)}* Vin

• If you remember, the cuttoff region of I-V characteristics curve of our Field Effect Transistor, when the max negative voltage is applied to the Gate source region and eventually the Field Effect Transistor_ FET starts acting as a very high resistance.
• That resistance lies in the range of Mega Ohms.
• In this case the output voltage Vout is nearly equal to the input voltage which was VGS.

FET as Phase shift oscillator

• Field Effect Transistors are ideal to be used as phase shift oscillators.
• Phase shift oscillators are used to generate signals with wide range of frequencies.
• Field Effect Transistors can be used for amplifying as well as for feedback loop operation, that is the reason they are excellent to work as phase shift oscillators.
• Field Effect Transistor_ FETs have high input impedance, so there is a very less loading effect when they are used as phase shift oscillators.
• Most of the times N channel JFETs are used for this purpose.

• You can observe the Field Effect Transistors as phase shift oscillators in GPS units, musical instruments and many other places where audio signals are modulated such as voice synthesis.

FET as Cascode amplifier

• The word case code has been derived from the phrase " Cascade to Cathode".
• Cascode circuits are made up of two components, the first one is the transconductance amplifier and the second one is the buffer amplifier.
• Cascode amplifiers are generally made using Field-Effect Transistors due to their high input resistance.
• We use cascode amplifiers because of their quality of having low input capacitance, otherwise, the normally used common amplifiers have a higher value of input capacitance in general than the cascode amplifiers.
• Although the voltage gain is the same for both the amplifiers which is again a win-win situation for
• Cascode amplifiers using Field-Effect Transistors.

FET in Multiplexer

• Let us first discuss the function of a multiplexer, a multiplexer collects different signals from different sources to present as a single output signal. Imagine a whole year of hard work and the end result is summarized in a single result card after the exam!
• Junction Field-Effect Transistors are used to construct the multiplexer circuit.
• Each Field Effect Transistor act as an SPST.
• In case you don't know about the SPST, let me tell you, it is the single pole single throw switch that generates one output from one input.
• An SPST is used as an on-off switch in circuits.

Consider the circuit diagram given below;

• All input signals get blocked when the control signals are made more negative than the Gate source voltage VGS.
• This condition blocks all the input signals.
• By turning any one of the control voltages V1, V2, or V3 to zero we can obtain a single desired output wave.
• Consider if ye turn V2 to Zero we will obtain a triangular signal.
• If we turn V3 to zero, you can yourself figure out from the circuit diagram, the wave signal you would get, Go! Scroll up!
• So this is how the Field Effect Transistors are used in multiplexers.

FET as Low noise input amplifier

• How you define noise? A sound that is unpleasant to the ears or when talking of signals a disturbance that causes unnecessary turbulence in the desired output making it meager or weak.
• Noise is produced in many mechanical and electrical instruments but sometimes for a few things it is tolerable and sometimes it is not!
• Just imagine disturbing noise when you are streaming a video or audio, a loud signal which blurs out music during your sunny beach day on your radio, nobody wants that! That is why Field effect transistors are used for low noise amplification.
• Noise has nothing to do with signal strength which is why it is always there, even when you have ended your live stream!
• Noise production is a drawback of many electronic devices but the bright side is that our Field effect transistors make a little less noise especially if they are used in the front end of the signal receiver.
• Field-effect transistors are a bit noisy too, but I have a solution for it, MOSFETs are used where even a little bit of noise can't be tolerated, don't worry we would talk about MOSFETs in our next article!
• So, lastly, we can say that, if we use a Field-effect transistor_ FET on the front end, there is lesser amplification of undesirable signal in our generated output.

FET as Current limiter

• Junction Field Effect transistors can be used to make a current limiting circuit.
• By this characteristic and arrangement, constant-current diodes and current regulators are made, let's discuss the process, but firstly refer to the circuit diagram for better understanding.
• When there is an excess of supply voltage due to any discrepancies in the system, the Junction Field Effect transistor immediately starts operating in its active or saturated region, I hope, by now you are well aware of the active region of the Junction Field Effect transistor, if not, refer to the section of I-V characteristics graph and its explanation!
• At this instance, the Junction Field Effect transistor acts as a source of the current itself and prevents any further load current.

So friends, this last segment concludes our discussion on Field Effect Transistors(FET), I hope you have learned something new from this discussion. For any suggestions or constructive criticism or a little bit of appreciation, you can use the comment section below. See you soon with the next topic, have a good day ahead!

RC Electronic Circuits Simulation in Proteus ISIS

Hello friends! Welcome to the Engineering components. Today, We are talking about the very common topic of electronic devices. In this tutorial, we'll pick very common components and learn about their role in circuits. If you are a beginner in the world of electronics, you must read this article till the end because we'll learn all the things from scratch till the completion of the circuit. In this article, you will learn:

1. Introduction to electronic circuits
2. Categories of electronic circuits.
3. Introduction to Resistor and Capacitor.
4. What are RC Circuits?
5. Simulation of R Circuits in Proteus ISIS.

Let's look at the description.

Introduction to Electronic Circuits

We come across many circuits in our daily lives, some of them are electrical circuits and some are electronic circuits. There are many differences between them but the main difference is, that electrical circuits do not have decision-making capacity whilst electronic circuits do have this ability. In electronic circuits, we power up the components with the mean power source and get the output. Hence we may define the electronic circuits as:

• "The electronic circuits are the types of circuits in which the individual electronic components are used that are connected to the power source with the help of wires so that the current can pass through the components."

The electronic circuits are also called discrete circuits because they are somehow, opposite to the integrated circuits. Most of the circuits use a combination of electrical and electronic circuits.

Categories of Electronic components

As we know, electronic components are used in many ways. For convenience, we divide the electronic components into categories. These are categories into two main sections:

1. Active Components.
2. Passive components.

The main focus of this article is passive components. The passive components include Capacitor, Resistor and Inductor. These are symbolized as C, R and L respectively. We'll learn about the first two of them today.

Introduction to Resistor and capacitor In electronic circuits

The Resistor and capacitor may be said to be the backbone of thousands of electronic circuits. To design a circuit, one should have a clear concept of these components. So, Let's have their introductions:

Resistor in Electronic Circuits

As the name implies, the resistor shows the resistance for the current in the circuit. It has a tube-like shape that has a molded figure and has a wire at the start and end. One may define the resistor as:

• The resistor is a passive, bi-terminal electrical component that is used in the circuit to have the electrical resistance in the current. When we use it in electronic circuits, it reduces the sudden current flow in the circuits, biases the active elements, divides the voltages in the circuit and performs such other tasks.

Current is the flow of electrons, this flow should be resisted by some mean, so that the components used in the circuit will be safe from damage. To control this opposition, one must have a clear idea about the resistance. The resistance is the measure of the property of the resistor to oppose the current in a circuit. The resistance of the resistor is symbolized by the strip of different colors. Each color has a meaning of different value.

Capacitor in Electronic Circuits

The capacitor works like a battery. The body of the capacitor is so simple and easy to understand, yet plays an important role in many types of circuits. The introduction of Capacitor is given next:

• The capacitor is an electrical component consists of two metallic plates and two wires connected with two plates that store energy passes through it in the form of an electrostatic field in between its two metallic plates. Its body is packed in an envelope.

As you can see in the picture, capacitors are manufactured in the form of a tube-like shape with two wires that are used to connect within the circuit. The capacitors are made in a variety of ranges according to their role in the circuit.

RC Electronic Circuits

As we know the Resistor is denoted as R and the capacitor is denoted by C. The RC circuits are the simple and easy circuits to understand.  We introduce the RC Electronic circuits as:

"The RC Circuits are the Resistor-Capacitor circuit in that consist of only resistor and capacitor as passive components of capacitor and these are connected with the current or voltage source according to the type of circuit."

One should keep in mind that we are talking about the category of passive components right now. Otherwise, some other components such as the power generating component are also used in the circuit. The are two categories of RC Circuits mentioned next:

1. RC Series circuit.
2. RC Parallel circuit.

RC Series circuits are the ones in which the resistor and capacitors are connected in series whereas, when we talk about the RC Parallel circuit, the R and C are connected in parallel to each other. RC circuits are also called the filter circuit or network circuit because many RC circuits are used to filter the unwanted frequencies of signals from the circuit and keep only the required ones. The RC Circuits are further classified on the basis of the number of components used in the circuit. The circuit is called the first-ordered RC Circuit if it contains only one resistor and one capacitor. Similarly, if it has two resistors and capacitors then the circuit is called the second ordered RC Circuit. To have a clear idea about the circuit, design it on the Proteus.

RC Electronic circuits in Proteus ISIS

To experiment, just follow the steps given next:

Required Components

1. Resistor
2. Capacitor
3. Battery
4. Connecting wires

Procedure

• Start your Proteus software.
• Click on the "P" button and choose the required components one by one.
• Arrange these components in the working area.
• Connect the components with connecting wires.
• Play the circuit with the play button present on the lower-left corner of the screen.

This image shows two types of circuits. The upper circuit is the RC Series circuit and the lower circuit is the RC Parallel circuit. Hence today, we learned about the introduction of Electronic circuits, we saw what are RC circuits, their components and their types depending upon different parameters. We also simulated the circuits in Proteus.

Diode: Definition, Symbol, Working, Characteristics, Types and Applications

Hello friends, I hope you all are happy, healthy, and, content. Today, our discussion is all about "Diodes". Whoever has been a science student, knows about diodes. Although it seems to be a tiny component of a circuit, apparently it is true but it has a lot of complexities or you can say, it's a storm in a teacup. You might have read a lot about diodes in physics, in today's discussion we would be moving step by step into the pool of diodes from definition to working of diodes, their types, and then lastly its applications. Let's get started!

Diode Definition

First things first, Let's define diode,

• A diode is a basic discreet electronic component made up of semiconductor material, used in electronic circuits, which allows unidirectional current to flow through it, i.e it only conducts current in one direction.
• You must be thinking, how is it possible for a device to conduct electricity in only one direction only, even when it has two terminals?

• The answer lies in making of a diode, a diode has zero resistance in one direction, meanwhile, the other direction has infinite resistance, hence maintaining the flow in only one direction hindering the flow in other direction, but keep one thing in mind, its an ideal case, otherwise a little bit of current flow is always there and ideal cases do not exist!
• A diode can act as a conductor and as an insulator as well. When the diode is reverse biased it acts as an insulator meanwhile when a diode is forward biased, it acts as a conductor.
• Diodes are mainly made up of two famous semiconductors silicon and Germanium.
• There are several different types of a diode, make of each one differs according to its function and the way it transmits current, don't worry we are going to have a detailed account of it soon.

Diode symbol

• The above symbol represents a diode, it's the symbol for a basic diode, let me clear one thing for you, there are several different types of diodes that we would be studying next and each one is represented with a different symbol accordingly. So, do not doubt yourself when you see a slightly different one!
• You can observe two ends or two terminals labeled as cathode and anode respectively.
• The Arrowhead represents the anode and direction of current flow.
• The other end is the cathode represented as a line attached to the terminal vertex of the triangle representing the anode.

History of Diode

Here is a brief account of the history of diodes, a little touch-up hurts no one!

• So, the History of diodes dates back to 1900 when the thermionic diodes and semiconductor diodes were made for radio.
• Vacuum tube diodes were the trendiest items of early 1950 being used and altered by several scientists through different experiments such as Fredrick Guthrie and Thomas Edison.
• Fleming valve was the first recognized diode of its age with all the elements present in a diode in the true sense.
• In world war ll, crystal diodes and Crystal rectifiers were used intensively in radar systems which led to extreme usage and development in the diode world, all thanks to their wide window of utility.

Working and Construction of Diode

In order to understand the working of a diode, let us first discuss its basic structure, how would you understand the working until unless you understand the make and build of a thing!

The basic structure of a Diode

• A basic diode is made up of a semiconductor, a p-type semiconductor and an n-type semiconductor joined together. Do you have a basic idea of semiconductors? Semiconductors are materials that have properties lying within the spectrum of metals and nonmetals, you can read our detailed article on the periodic table if you want to know more about the elements and their respective properties.
• Anyhow, we were talking about semiconductors, semiconductors are of two types, Intrinsic semiconductors, and extrinsic semiconductors.
• Intrinsic semiconductors are pure semiconductors without any additional impurity. They include silicon and germanium.
• Extrinsic semiconductors are the ones with doping, don't worry we are about to discuss it next.
• I hope you have a general idea about p-type and n-type semiconductors, if not, we have got you covered. Read the next section for details;

Doping in Semiconductors

To understand p-type and n-type semiconductors, you must be aware of the concept of Doping. We can define doping as; Doping is the intentional addition of impurities into an intrinsic semiconductor. It changes the physical, electrical, and optical characteristics of that very intrinsic semiconductor.

1. p-type semiconductors

• A p-type semiconductor is made by doping i.e adding an impurity which is an electron acceptor by nature into the semiconductor i.e gallium and boron are added to the silicon, turning it into a p-type semiconductor.
• You must be thinking about why they are called p-type semiconductors? Let me tell you, The name p-type is given due to the presence of a positive charge on the semiconductor.
• The p-type semiconductor contains a majority of holes and a minority of electrons.

2. n-type semiconductors

• The n-type semiconductor is made by doping the semiconductor with an electron donor element.
• The n-type semiconductor has a majority of electrons and a minority of holes.
• The name n-type is given due to the negative charge of electrons present in the semiconductor, you knew that already, or you didn't?
• Arsenic and phosphorus are used for the doping of silicone making it a n-type semiconductor.

Now we are done with the basics of n-type and p-type semiconductors, let us discuss their utility in making a semiconductor diode. The following section includes a breakdown of components and concepts lying in the scope of diodes.

PN junction

• Our discussion would be incomplete without the PN junction, can you think of a diode without it? Yes, there are a few exceptions but typical ones necessarily have a PN junction.
• As I have told you earlier semiconductor diodes are made up of n and p-type semiconductor materials joined together to make a diode.
• The merger of these two materials is responsible for the making of PN junction made between the contact point of two materials.
• After the formation of the PN junction, the process of diffusion takes place, we would be discussing it next, don't worry!

Depletion Region

• There is a considerable difference between the amount of holes and electrons on both sides. If you know about the simple concept of diffusion, a particle moves from the area of higher concentration to the area of lower concentration and vice versa, same happens here, the holes from the p side move to the n side of the diode.
• Meanwhile, electrons move from the n side where they are higher in concentration to the p side where they are lower in concentration.
• This movement of electrons and holes generate a diffusion current leading to the formation of an immobile layer of positive and negative ion on the PN Junction, this layer is called depletion region.
• Now you must be thinking why I'm telling you about the depletion region? Why is it necessary?
• The depletion region limits the diffusion of electrons and holes from the opposite doped semiconductor portion, otherwise, after the constant diffusion, all the electrons and holes would have been diffused into each other leaving behind almost no charge carriers to conduct the current when the diode is connected to the battery.
• On the other hand, the size of the depletion region maintains the current flow and resistance. Larger the depletion region, the Larger the resistance. You will understand this concept more easily once we would be done discussing the forward and reverse biasing of the diode and characteristics of the diode. Stay tuned!

Biasing conditions of the Diode

To understand the working of a simple diode, you must know about the biasing conditions of the diode first,

• Forward biasing

• Reverse biasing

• Zero biasing

1. Forward Biasing

• When the positive terminal of the battery is connected to the p-type semiconductor meanwhile the n-type semiconductor is connected to the negative terminal of the battery it is called forward biasing of the diode.
• The depletion region is very thin in this case and it is easier for the forward Voltage or VF to overcome the depletion region for conduction of current.
• PN junction offers very little resistance to the current flow due to the thin depletion region.
• In forward biasing condition, an ideal diode has zero resistance, but as I told you earlier, an ideal condition does not exist.

 2. Reverse Biasing

• In reverse biasing condition, negative terminal is connected to the p-type region of the diode, meanwhile positive terminal is connected to the n-type region of the diode.
• The depletion region in this case is very thick.
• The PN junction in reverse biasing offers a very high resistance due to the thickness of the depletion region.
• A diode in ideal condition when reverse biased has infinite resistance.

3. Zero biasing

• Voltage has not been applied to the diode, in zero biasing condition.
• In zero biasing conditions, there is a thermal equilibrium in the diode.
• The natural potential barrier is present in the diode, which is 0.5V to 0.7V for silicon and for germanium this potential barrier is 0.3V.

Characteristics of diode

• We have already learned about the forward and reversed biased condition of the diode, in order to understand the current and Voltage characteristics of both the conditions , consider the following graph consisting of a single characteristic curve.
• The voltage is usually plotted on the x-axis of the graph meanwhile the current takes the y- axis.
• The starting point of the graph can be seen in the center, where both the values i.e current and the voltage is zero.
• Forward current can be observed extending upwards, above the horizontal axis meanwhile, reverse current extends downwards.
• In the upper right corner you can see the combined values of forward voltage and forward current.
• The lower left corner shows the combined value of reverse current and reverse voltage.

Forward Characteristic of Diode

• We have already studied about the forward biasing of the diode, forward characteristic corresponds to that.
• In forward characteristic the current IF flows in forward direction and depends on the amount of forward voltage VF.
• The relationship between VF and IF is called IV characteristic of diode or ampere volt relationship, this is the point of focus of our discussion!
• When forward voltage is zero i.e
• 0V, the forward current IF is also zero i.e 0mA.
• From the graph we can clearly see that the increase in forward voltage , VF causes can increase in forward Current IF, when the value starts from the point 0 of the given graph.
• Now its the turn for the most important point of the curve, the knee voltage denoted as VK.
• You must be thinking why we call it knee voltage? And how is it achieved? Have a look at the line formed , it seems like an extended knee, so we call it knee voltage. Knee voltage is the point where forward voltage VF is large enough to overcome the depletion region of the diode and there is surge in forward current IF, marking the highest point of voltage, knee Voltage VK.
• Knee voltage varies from material to material i.e VK is material specific.

Reverse Characteristic of Diode

• During the reverse biased condition, a very little current is conducted by the diode.
• You can observe the Reverse Voltage and Reverse current in the graph, represented by VR and IR respectively.
• There is a very little amount of charge carriers which conduct the reverse current IR.

• We cannot observe a considerable increase in Reverse current IR even with a large amount of Reverse Voltage VR.
• VBR is one of the most important characteristics of the reverse biased diode, its the breakdown voltage of the reverse biased diode which refers to the amount of voltage at which the reverse current IR increases rapidly breaking the PN junction.

Diode Equation

Following equation refers to the ideal condition of the current and voltage of a diode either in forward biased or reversed biased condition; The equation corresponds to the following things;

• I is the diode current sometimes represented as ID as well.
• IS is the reverse bias saturation current and is not constant for any device, it usually varies with temperature.
• VD is the voltage across the diode
• VT is the thermal voltage which is equal to 25.8563 mV at 300 K.
• In other conditions, Vt equals Boltzmann's constant × temperature ÷ electron charge i.e kT/q
• n is the ideality factor, also called the quality factor and emission coefficient.
• The equation is called Shockley ideal diode equation in which the ideality factor is preset to 1.
• In other conditions, the ideality factor can range from 1 to 2 or maybe higher than that in some cases.
• In forward bias condition, the ideality factor is almost negligible and the equation can be written as;

Types of Diode

With the advancement in technology and increasing human needs, diodes also changed shapes and took over several functions, there are several types of the diode, some of them are explained below;

1. Zener Diode

• It is a heavily doped PN junction diode that works in a reverse-biased condition when a certain specified voltage is reached, this voltage is called Zener Voltage.
• The Breakdown voltage marks the best possible functional capacity of the diode.
• Zener diode is used for voltage regulation, you may observe one in clipping operations, circuit protectors, surge suppressors, and switching applications among the countless other uses which can not be listed here at once.
• They are available in different zener voltages and can be used according to the need.

2. PIN diode

• A PIN diode is a semiconductor diode having a wide undoped semiconductor region sandwiched between heavily doped n-type and p-type regions.
• PIN photodiode doesn't rectify or distort the signal.
• They have a wide range of applications being used in microwave switches and radars.
• PIN diodes are also used in fiber optics and photodetectors.
• Gamma rays and x-ray photons can be detected using a PIN photodiode.

3. Schottky diode

• This is not like a typical PN junction diode, Schottky diode is made by the combination of the metal with the n-type semiconductor.
• Because of the absence of a typical P and N-type combination, we do not see a depletion region in this diode.
• They are also called the hot carrier or Schottky barrier diode.
• These are highly efficient and used in digital devices which are highly sophisticated and fast.

4. Photodiode

• This is one of the most famous types of diodes which are almost known by everyone. A photodiode is a semiconductor p n junction.
• It works in a reverse-biased condition when current is generated on the absorption of light, i.e it converts light in current.
• They have countless applications in the medical, automotive, and other industrial fields such as CAT scanners, PET scanners, light meters, cameras, bar code scanners, and whatnot!
• Photodiodes are used in signal demodulation, detection, and switching.

5. Laser Diode

• Have you ever thought of the full form of the word LASER? You might have, but for the people who haven't, here it is, light amplification by stimulated emission of radiation.
• Laser diode works on the principle of stimulated emission.
• A laser diode works exactly opposite to the photodiode, it converts the voltage into high-intensity coherent light.
• The p-n junction of acts as the active region or laser medium of the diode.
• Laser diodes are highly efficient and can be produced at much lower costs than other diodes known to us.
• Laser diode requires a lower power to operate and produce coherent light than other diodes.
• There are countless applications of laser diodes being used in radiological scans, barcode readers, laser pointers, laser printing, and much more.

6. Tunnel Diode

• A tunnel diode is also known as Esaki diode.
• Tunnel diode as the name suggests works on the principle of tunneling, based on quantum mechanical effects.
• These diodes have a 10nm pn junction which is heavily doped which works on the negative conductance property of the semiconductors.
• Tunnel diodes are used in high-frequency oscillators and receivers, microwave circuits are also made using them.
• They are not widely used in every other circuit because of their low current.

7. Varactor diode

• Varactor diode is made up of two things, a diode and a variable capacitor. They are used as voltage-controlled capacitors.
• It is also named as varicap diode.
• A varactor works in a reverse-biased condition, I hope you know how the reverse-biased condition works, don't fret, if you still don't know, give it another read from the previous sections.
• They are used in frequency modulation, RF phase shifter, and have multiple other applications.

8. Vacuum Diode

• It is the simplest form of the diode and works on the principle of thermionic emission. It does not a PN junction, which are present in the modern day diodes, it's an old school one!
• The cathode and anode are made up of specified metals, different metals are used for the purpose.
• Both the cathode and anode are enclosed in a vacuum tube.
• The cathode is heated with the help of a power supply which in turn releases the electrons, these electrons are then attracted towards the anode.
• The stream of electrons flows from cathode to anode generating current.
• Vacuum diode only works in forward biased condition, in reverse biased condition, it does not work.
• It is the most primitive form of the diode and was used in almost every electronic appliance in the twentieth century, when technology was about to touch the new horizons, there were many available options such as radio, television, computers, and telephones to name a few with a vacuum diode as their functional component.

9. LED

• First things first, please do not call it LED diode, led already is a complete word, Light emitting diode, you can not write it , light emitting diode diode, or can you?
• Who is not aware of the light emitting diodes in this modern age? With endless advertisements and media campaigns, we all have a vague notion about LEDs to an extent.
• Light emitting diodes are similar to laser diodes but they do not emit laser beams on applying voltage.
• LEDs work in forward biased conditions i.e on applying and increasing voltage, current also increases emitting a non-coherent light.
• They are widely used in digital devices for display screens, optical fiber communication, and several detection systems.

10. Gunn diode

• If you remember, I told you earlier about the diodes without a PN junction, Gunn diode is one of them.
• The Gunn diode is a transferred electron device TED, which works on the Gunn effect, named after a scientist. It's a negative differential resistance device.
• There are three regions in total, N- region is the negative region, which is sandwiched between two P+ regions which are heavily doped.
• The materials used in the formation are Indium phosphide and Gallium Arsenide.
• It is a low-power oscillator used in the production of microwaves.
• Gunn diode provides high reliability, and high bandwidth at comparatively lower costs than other available options.

Applications and examples of Diode

As we are at the terminal stage of our discussion, you must be aware of the wide window of utilities we have for diodes, here is the list of few uses of diode which you might already know to an extent;

1. Inverter Technology

• You must be aware of the inverter technology used in modern appliances, they make use of rectifiers which convert the alternating current into direct current.
• Power conversion with the help of diodes has worked as the game-changer in the electronic world, the conversion of alternating current into direct current or higher dc voltage has revolutionized modern technology. You might have seen endless advertisements of invertors technology in home appliances such as air conditioners, and refrigerators to name a few.
• Automotive alternators and voltage multipliers are the well-known examples in this respect.

2. Boolean logic gates

• All of us have thoroughly learned boolean algebra and its logic gates in physics or somehow in computer sciences as well, I always had a love-hate relationship with the logic gates, I still don't know why!
• Those logic gates especially the AND and OR logic gates can be made using diodes and other necessary components required to complete the circuit.
• Diode logic gates were used a lot in the earlier production of computers when other available options were not cost-effective.

3. Signal Demodulation

• Do you know, what is signal demodulation? Let me answer this first, Picking up the actual signal from the modulated wave is called signal demodulation.
• Signal demodulation is carried out by the diode, usually for radio signals.
• The basic task is to remove the negative signals from the carrier wave, generating a clear output signal in terms of sound or an image.
• Signal demodulation is one of the most important things done by diodes.
• Can you guess how this process is carried out? The AM envelope detector, which is simply a diode and an RC circuit the leads for demodulation.

4. Electronics

• From transistors and rectifiers to Light emitting diodes and an endless spectrum of usage, diodes have a significant place in electronics.
• Diodes have plenty of variants to choose from, such as Diode 1n4004 is the most famous diode, which is used for rectification. It has a maximum current carrying capacity of 1A, there are plenty of options you can use as per your requirement.
• One of the most observed examples includes the LEDs, the festive fairy lights to large traffic signal lights and radiological detectors, we all have seen endless diodes in our lives.
• Zener diodes and tuning diodes act as voltage regulators, without them, your circuits would suffer a burnout soon, nobody can withstand a financial and human loss in general at such a large scale.
• We have discussed all of them in detail, you can refer to the section above, in case you have skipped it!

5. Bypass Diodes in Solar panels

• Hot spot heating is one of the many problems faced by the solar system, the solar cell gets damaged due to the low output in presence of shade, dust or snow or any other factors hindering the sunlight to the solar cell.
• Now, you must be thinking about how a hotspot is formed even though the cell itself is not working?
• It is absolutely true that the cell is not working, but the other cells are functional and the current of these cells flow through this faulty cell, heating it up and making a hot spot.
• For this purpose, to protect the faulty cell, bypass diodes are used. This is one of the least celebrated uses of diode indeed!
• These bypass diodes are connected in parallel with the solar cells which helps to reduce the flow of current through the flawed solar cell, making the current flow through an external circuit.

6. Diodes as Clippers

• Let's first discuss the function of a clipper circuit, in case you don't know, a clipper circuit is used to cut down certain parts of the signal, without disturbing the actual waveform, imagine you are making a sandwich with the sandwich cutter, upon cutting with the stencil the sandwich takes the shape of the cutter only from the corners, shedding off the extra parts and bits, but the actual build and assembly of the sandwich is not disturbed, the clipper does the same with the signals.
• These clippers are usually of two types, shunt clippers and series clipper, depending on their function.

7. Diodes in Radiology

• Have you ever been to the hospital for a scan? For a broken bone or for a diagnostic one?
• Laser diodes are the ones used for this purpose, we have already read about them in detail in our previous section.
• Nowadays, laser diodes are even used for surgical treatments such as retinal repair, and other eye-related surgeries. Lithotripsy is also done by laser, the stone in your kidney is broken from outside of the body, through a laser beam without any incision. Isn't it revolutionary? Definitely, it is!

So, friends, it was all about diodes, I presume you have a clear understanding of many concepts related to diodes including their basic structure, working,  types, and applications. I tried to keep it simple but significant, You can re-read the section you least understood, it happens to everyone and it helps. See you with another soon, have a good day ahead!

Real Time Embedded Systems: Definition, Types, Examples and Applications

Hello friends, I hope you are happy, healthy and content. We have been discussing embedded systems lately and this discussion would be incomplete without an in-depth discussion on Real time embedded systems. You might have observed their utility and their absolute need in our constantly changing external and internal environment, the ease of managing the room temperature with a single tap, generating several results with a single click and streaming videos and playing games anytime and anywhere are the blessings of real time embedded systems.

Definition of Real Time Embedded Systems

Real time embedded systems can be defined as;

• "The embedded systems which respond to real time situation with the help of its embedded software and hardware, within the specified time constraints are called real time embedded systems."

Characteristics of a Real-Time Embedded System

Real time embedded systems must have the following characteristics;

1. Constant Response:

• A real-time embedded system always responds in the same manner to a certain situation, it is not allowed to deviate from its normal designated output. An air-conditioner is not allowed to throw hot air in summers.

2. Deadline:

• A deadline is crucial to the working of an embedded system, a missed deadline can cost lives and finances.

3. Accuracy:

• In case of any malfunctioning, the system failure can cause havoc, what would happen if the pacemaker can't maintain the heartbeat, patient would eventually die!

4. Quick Response:

• It is the most important characteristic of all, the real-time embedded system must be swift enough to respond to the changing external environment with immediate effect.

Components of Real Time Embedded Systems

We have already discussed the embedded system components in detail within our previous article, for a quick overview , let's revise the basic things;

1. Hardware

• The hardware parts include a microcontroller or a microprocessor, Input and Output ports, sensors , actuators , relays, power supply or batteries and several other peripheral parts according to the design and function of the embedded system.

2. Software

• Real time embedded systems have embedded software which directs the system for performing designated tasks.
• For a real time embedded system, embedded operating systems software must have the critical feature of task scheduling, because we need a system which sticks to the deadline and performs the task within that limited time range. Let's have a look, how task scheduling is done;

Task Scheduling

To understand task scheduling you must understand pre-emptive and non-preemptive scheduling.

Preemptive scheduling

IT refers to the scheduling of tasks based on priority, it is a flexible process and interruption between the tasks doesn't upset the whole system. It's same as you are washing dishes and someone ask for a clean dish at immediate basis, you leave the thing in your hands and start washing that dish which is needed immediately!

Non- preemptive scheduling

it is a rigid process, the other task at hand has to wait until the first one has been completed. Now, you are well aware of the types of approaches used in task scheduling, its time for a detailed outlook on the basic types of Task Scheduling done in the real time embedded systems.

First Come First Served Task Scheduling

• As the name clearly indicates, the task that is assigned first is completed first.
• This is a non-preemptive scheduling approach.
• The system is highly efficient and tries to complete the task real quick and responds quickly.

Round Robin Task Scheduling

• In this task scheduling technique the preemptive approach is applied, but there is a difference, it doesn't priorities a task, instead it allocates the time for each task.
• Its same as, you have an exam tomorrow morning and you allocate 2 hours to each chapter for revision!

Shortest Job First Task Scheduling

• All of us have done this at some point of our lives, if you aren't a very diligent student, you choose the shortest paragraph to read first. Isn't it?
• Same is done by the preemptive scheduling system in this case, the task which can be performed quickly , is chosen and performed first.
• If a new task is assigned which can be performed earlier than the one being performed at hand, the system starts performing the shorter one which has just arrived, unfair! Isn't it?

Priority Scheduling

• Let's suppose its your best friends birthday and you are in charge of all the celebrations or we can say a surprise birthday party, what would you arrange first? snacks?, decorations? or a birthday cake? The answer is clear , it would be a birthday cake winning the priority list.
• Same is the case with priority scheduling, the system prioritizes all the tasks at hand, but the one with utmost urgency and priority is performed first.
• This system can be designed using both the preemptive and non-preemptive approaches.

Real time operating system

• Real time embedded systems are everywhere around us and have real time operating system as their basic component, they are almost similar to embedded operating systems , only having a few particular features different from the typical embedded operating systems due to the task specifications.
• RTOS are implied in the embedded systems which are time sensitive.
• Time constraints are the key, a task completed after due time or deadline would be rendered useless or would have a negative impact on the users. You can't enter your lecture hall after the starting time of your lecture without feeling guilty of being late!
• Time maintenance component is crucial to the real time operating system, tasks are specified and given preference according to the time constraints of each task.

You can refer to the diagram for the components of a real time embedded system.

Types of Real Time Embedded Systems

As we are done with the definition and components of a real time embedded system, being made up of real time operating system, embedded software and hardware.It would be easier to learn their types. Real Time embedded systems have the following three types, we would discuss each of them in detail.

1. Soft Real Time Embedded Systems

Following are the characteristics of soft real time embedded systems;

• In soft real time embedded systems, timeliness of a task poses a positive impact on the system, but it is not crucial for the performance of the system.
• Missing a deadline would not degrade the performance of the whole embedded system.

Example of Soft Real Time Embedded System

A data acquisition system can tolerate delays and hence its a soft real time embedded system. Other examples include, websites, computer games, cellular networks, online database and multimedia transmission and reception.

2. Hard Real Time Embedded Systems

Following are the characteristics of hard real time embedded systems;

• For a hard real time embedded system, time is crucial.
• The output must be completely on time, the prescribed deadline can not be missed in any case. You can't submit your exam paper after the time is over, or can you?
• In case a deadline is missed, it would be regarded as a system failure.

Following table shows the brief account of characteristic features for both soft and hard real time embedded systems.

Example of Hard Real Time Embedded System

The missile launch system is one of the most suitable examples in such systems, if the missile is not launched in time, it would miss the target claiming a huge environmental, economic and human loss. Other examples include medical equipment and handheld devices, avionics, industrial control systems, and transportation control.

3. Firm Real Time Embedded Systems

Following are the characteristics of firm real time embedded systems;

• Timelines of a task are crucial but the missed deadline can be compensated as it occurs rarely.
• Missed deadline doesn't degrade the system performance.
• In case of the missed deadline, The system continues to perform and discard the delayed response.

Example of Firm Real Time Embedded Systems

A fully automated assembly line doesn't crash when a task isn't performed in time, it rather ignores that missed part and continues to complete the rest.

Examples of Real Time Embedded System

• Real time embedded systems examples are being listed below, we will only discuss the few basic ones in detail out of an endless list.

Cardiac Pacemaker - A Real Time Embedded System

• First one on the list is a pacemaker, let's have a brief idea about the function of pacemakers first, a pacemaker maintains the heart beat, so is crucial to human life. A pacemaker is a real time embedded system.

• The sensors present in the pacemaker detect the intensity of the beat and send an electrical signal, if its too low to maintain normal function of the heart, in response to this signal an electrical impulse is generated to maintain the already diminishing heartbeat, your heart can't skip a beat, otherwise you'd die of heart attack! It only happens in movies.

Airbags- A real Time Embedded System

• Who is not aware of the importance of air bags in this era of modern vehicles! Airbags are indeed one of the most celebrated safety inventions of modern age.
• Air bags are necessary for human survival in case of a road accident which is obviously a life threatening condition.
• The airbags are inflated on the detection of collision or crash by the sensors, upon detection certain chemical react instantly to inflate the bags, providing cushion to the passengers to land on, saving passengers from serious injuries.
• Hence, airbag system of a car is a real time embedded system which works within strict time constraints, otherwise it would be useless for an airbag to inflate after the passenger has already got a whiplash injury during collision, ending up in a hospital bed or a deathbed.

Manufacturing Assembly Line

• The above mentioned examples were the life threatening ones, the one we are about to discuss is light and crispy!
• Now consider a manufacturing assembly line for production of Lays, the one you have seen in your childhood on national geographic, or maybe you were lucky enough to see it in real!
• What would happen if the automated system fails to fill in the chips in designed time? It doesn't happen that much, but just imagine for an instance!
• That one delayed step would disturb all the preceding steps in line, such as sealing and flavouring the packets.
• This is not life threatening situation , but a delay that would cost millions or much more. Packaging is just the terminal step, you can yourself imagine the importance of timelines in the whole manufacturing process.
• Or in another instance the missed step would be ignored if it is not on a large scale and the process would continue, the same thing that happens in firm real time embedded systems. It all about programming the system according to your personal preference and available resources.
• Thus a manufacturing assembly line is a real time embedded system, which needs to be in time.

Crusie Control of a Car

• Cruise control which once seemed a crazy concept a while ago is now a new normal for longer trips.
• It's a real-time embedded system that controls the speed of a car.
• The real-time embedded software algorithm has basic features of keeping the car at a preset speed as indicated by the driver, maintaining a safe measurable distance from a preceding vehicle, and lastly it is designed to switch between the two discussed modes according to the real-time situation on road.
• A minor miscalculation of the speed and distance would cause havoc on the road, thus real time embedded systems need to be accurate and on time during their performance.

Safety critical systems

• We have discussed safety critical systems in one of our previous articles as well, but a discussion on real time embedded system without an example of a safety critical system is incomplete.
• First things first, Safety Critical Systems are real time embedded systems.
• You might have got a slight idea about the safety critical systems from their name, The systems which can't afford delay are called safety critical systems, their output delay can claim a human life, can pose serious financial and environmental crisis.
• One the most common example is a missile launching system.
• Missile launching system is a real time embedded system, imagine the destruction with one single delay or miscalculated response. Another example include shuttle launch in space which is also a safety critical system.

Applications of Real Time Embedded Systems

  Real time embedded system applications are countless, a few popular ones are being discussed below;

Medical Industry

• Real time embedded systems are deeply rooted into the healthcare sector either in the form of handheld devices such as insulin pump, BP apparatus, pulse oximeter or large devices such ECG machines, and industrial scanners, real time embedded systems are everywhere.
• These embedded systems have made diagnosis , treatment and prognosis much easier than before. Diagnosis and treatment would be a difficult thing to do without the real time embedded systems, how would you identify a tumor without a scan? How insulin levels would be checked? Nobody can deny the importance of real time embedded systems in the medical field.

Manufacturing and Assembly Lines

• Real time embedded systems have revolutionized the automation of production lines, you might see the fully automated processes of biscuits, chips and soda in documentaries or maybe in real. Have you ever thought how it is done? The mechanism and machinery behind the fully automated processes? These are large robots with real time embedded systems, performing their designated tasks in a real time environment.
• Control of internal environment according to the manufacturing process, for humidity , air pressure and temperature is also done by real time embedded systems. Would you ever like soggy lays? Or a soda without gas? A cookie without crunch? No! Nobody does! All these factors are controlled by real time embedded systems through predictive maintenance.

Military Operations

• Either it is a preventive or defensive approach, real time embedded systems are an essential part of a bigger picture in military armaments.
• You might have heard of guided missiles, detection systems and much more intelligent weapons, all these systems are real time embedded systems.
• In military SWaP size, weight and power is a decisive factor of winning and losing for the soldiers in the battlefield, real time embedded systems, reduce size and weight of the power gear and provides quicker and better turnover during a strike.
• Microcontroller technology has led to the reduction of production costs along with the manufacturing of lightweight power gear.

Home Automation

• You might have seen the central cooling and heating systems, smart lighting system, security system, fire alarm, security surveillance system and many other systems that are controlled by the sensors by collecting data from external environment, these are real time embedded systems which have added to the ease of human beings.
• All the above mentioned systems are controlled through internet but they can be regulated manually as well.
• We have already discussed in detail the concept of a Smart home, in which several electronic devices are connected to a central hub through internet. Real time embedded systems have helped a lot in turning this unpopular concept into reality. To say the least, it is indeed an expensive concept.

Automotive industry

• Automotive industry has reaped the benefits of the real time embedded systems to full extent.
• Can you imagine a car without a GPS system these days? No , its an absolute necessity now!
• Crusie control, smart parking, car tracking, traction control system, and a lot more which are a part of another bigger picture have real time embedded systems in them.
• Hybrid vehicles which consume less fuel and save environment are a gift of real time embedded systems as well.

Multimedia Systems

• Multimedia systems which provide the audio and video interface to their users, have real time embedded systems as their integral part.
• The gaming world would be incomplete if real time embedded systems are not implied, many of the modern games are also networked and played live among the users from all over the world at the same time.

So, friends, that's all about the Real Time Embedded Systems, I have tried to cover everything regarding this topic. I hope you have learned something new from this article. In case you want to add something new to the list of applications or examples of embedded systems, you can mention in the comment section below. See you soon with another topic. Have a good day ahead!

Arduino Pro Mini Library for Proteus V2.0

Hi Everyone! Glad to have you on board. In this post, we’ll cover the Arduino Pro Mini Library for Proteus V2.0. I have already discussed its previous version i.e. Arduino Pro Mini Proteus Library V(1.0). I keep getting bug reportings from our blog readers (for previous versions), so I have tried to remove these bugs in this newer version. But if you still find any bug/error, you can approach me in the section below. We have already shared many Proteus Libraries for Embedded sensors and these days we are trying to improve their versions. First, we will download this library in zip format and then will use it in our Proteus software to simulate Arduino Pro Mini. Before we go further, first we’ll detail what is Arduino Pro Mini.

What is Arduino Pro Mini?

• Introduced by Arduino.cc, Arduino Pro Mini is a compact, small-sized, sophisticated microcontroller board based on the Atmega328 microcontroller.

• This module features a total 14 digital I/O pins on the board, of which 6 pins are used as PWM.
• Incorporated with 8 analog pins, Arduino Pro Mini comes with a reset button and a small LED connected to pin 13.
• This unit is quite small compared to Arduino Uno i.e. 1/6^th of the size of Arduino Uno.

This was a brief insight into the Arduino Pro Mini V2. Let’s explain how to download the Arduino Pro Mini library and use it in your Proteus software. Let’s jump right in.

Arduino Pro Mini Library for Proteus V2.0

• First of all, download the Arduino Pro Mini Library for Proteus V2.0 by clicking the below button.

Arduino Pro Mini Library for Proteus V2.0

• You will get the downloaded file in zip format.
• Extract this zip file, in which you’ll find the folder named "Proteus Library Files".

Open this folder to get the further two files named:

• ArduinoProMini2TEP.dll
• ArduinoProMini2TEP.idx

Note:

• If you are facing problems in adding a library in Proteus 7 or 8 Professional, then have a look at How to add a new Library in Proteus 8 Professional.
• If you haven’t bought your Arduino Pro Mini yet, then you can buy it from this reliable source:

• Copy these files from “Proteus Library Files” and place them into the Library folder of your Proteus software.

• After placing the files in the library folder, open your Proteus software or restart (if it’s already running)
• Now look for the Arduino Pro Mini V2.0 by clicking the “Pick from Libraries” button as shown in the figure below:

• Select Arduino Pro Mini V2.0 and click OK.

• After clicking Ok, you’ll find the Arduino Pro Mini board in the proteus workspace as shown in the figure below:

• You’ve successfully placed the Arduino Pro Mini board in the proteus workspace.
• Next, we have to upload the hex file to run our board.

• To upload the hex file, you need to double-click the Arduino Pro Mini board.
• As you double click, the following image will appear:

• In this panel, you'll find the different properties of the Arduino Pro Mini board. Click the property named “Program File” to upload the hex file of your Arduino code.
• Upload the hex file of your code and click Ok.
• The 16MHz is the clock frequency of Arduino Pro Mini by default as shown in the properties panel.

Comparison with Old Proteus Library (V2.0 vs V1.0)

• In the figure below you'll see the comparison between version 1 Arduino Pro Mini Board (V1) and version 2 Arduino Pro Mini Board (V2).

• You can see in the above figure, V2 board is more compact and small-sized as compared to the V1 board.
• Now let's design a simulation of this Arduino Pro Mini board so that you can learn how to use it in proteus software.

Arduino Pro Mini LCD Interfacing

• Use the simulation that you’ve downloaded at the start or design on your own. I would suggest you to design on your own as it will help you learn many things along the process.
• Now, we have to interface a 20x4 LCD with the Arduino Pro Mini board.
• Design the circuit as shown below to interface the LCD with the Arduino Pro Mini:

• The data pins of the LCD are attached with pins 8,9,10 & 11 of Arduino Pro Mini while Enable & Reset of LCD are attached to Pin 12 & 13 of the Arduino board.
• Now compile the Arduino code available in the zip file and get the Hex File.

• Upload that Hex File in your Arduino Pro Mini Properties panel, as we did in the previous section.
• After interfacing LCD with the Arduino Pro Mini, click the RUN button and if everything goes fine, you will see the result as shown in below figure:

Summary

• Download Arduino Pro Mini Library Files in zip format.
• Copy files from the "Proteus Library Files"(Folder) and place them in the Library folder of Proteus software.
• Search for Arduino Pro Mini in Proteus software.
• Place Arduino Pro Mini in the Proteus workspace.
• Double click the board and open the properties panel to upload the HEX File.
• Design the circuit & run the simulation.

That’s all for today. Hope you’ve enjoyed reading this article. If you’re unsure or have any questions, you can approach me in the comment section below. I’d love to help you the best way I can. Feel free to share your valuable feedback and suggestions around the content we share. They help us create quality content tailored to your exact needs and requirements. Thank you for reading the article.

Arduino Mega 2560 Library for Proteus V2.0

Hi Guys! Happy to see you around. In this post today, I’ll detail the new version of Arduino Mega 2560 Library for Proteus V2.0. I have already detailed the Arduino Mega 2560 Library for Proteus that is the previous version of the Arduino Mega 2560 board. This new version of Arduino Mega 2560 is more efficient, robust, fast, powerful, and small in size. I keep getting messages requesting to design the library for the new version of Arduino Boards. So, today I’m willing to comply with your requests and have designed this library for the new version of Arduino Mega 2560. I have previously discussed the Arduino UNO Library for Proteus V2.0 and Arduino Mini Library for Proteus V2.0 In this tutorial, we will simulate Arduino Mega 2560 in Proteus. Initially, we will download this library in zip format and then will use it in our Proteus software to simulate Arduino Mega 2560. Before we read further, let’s go through what is Arduino Mega 2560?

What is Arduino Mega 2560?

• The Arduino Mega 2560 is a robust, powerful, application-type microcontroller board based on the Atmega2560 microcontroller.
• There are total 54 digital I/O pins incorporated on the board, including 15 pins for PWM.

• There are 16 analog pins available on the board. Moreover, the board contains a USB port to transfer the code from the computer to the module, and a DC power jack is included on the board to power up the module.

This was the little intro to Arduino Mega 2560. Let’s discuss how to download the Arduino Mega 2560 library and use it in your Proteus software. Let’s get started.

Arduino Mega 2560 Library for Proteus V2.0

First of all, download the Arduino Mega 2560 library for Proteus V2.0 by clicking the link below. Arduino Mega 2560 Library for Proteus V2.0 You will get the downloaded file in zip format.

• Extract this zip file where you’ll find the folder named "Proteus Library Files".

When you open this folder, you will find two files named:

• ArduinoMega25602TEP.dll
• ArduinoMega25602TEP.idx

Note:

• If you are facing problems in adding a library in Proteus 7 or 8 Professional, then you should read How to add new Library in Proteus 8 Professional.
• If you haven’t bought your Arduino Mega 2560 yet, then you can buy it from this reliable source:

• If you want to go through its technical specifications, features and pinout then you better have a look at Introduction to Arduino Mega 2560.

Now copy these files and place them in the libraries folder of your Proteus software.

• After placing the library files, open your Proteus software or restart (if it's already open).
• Now search for the Arduino Mega 2560 V2.0 by clicking the “Pick from Libraries” button as shown in the below figure.

• Select Arduino Mega 2560 V2.0 and click OK.

• Place Arduino Mega 2560 board in the Proteus workspace and it will appear as shown in the below figure.

• You’ve successfully placed the Arduino Mega 2560 V2.0 board in the proteus workspace.
• Now, we need to upload the hex file to simulate our board.

• To upload the hex file, double-click the Arduino Mega 2560 board.
• As you double click, it will return the following image.

In this panel, you can see the different properties of the Mega 2560 board. We have to click the property named “Program File” to upload the hex file of your Arduino code.

• Click this read detailing how to get hex file from Arduino software, if you don’t know already.
• Upload the hex file of your code and click Ok.
• The clock frequency of the Arduino board is 16MHz by default as shown in the properties panel.

Now let's design a simulation using this Arduino Mega 2560 board so that you get a clear insight on how to use it in proteus.

Comparison with Old Proteus Library (V2.0 vs V1.0)

• The following figure shows the comparison between version 1 Arduino Mega 2560 Board (V1) and version 2 Arduino Mega 2560 Board (V2).

• You can see in the above figure, V2 Arduino Mega 2560 board is more compact and small-sized as compared to the V1 Arduino Mega 2560 board.

Arduino Mega 2560 LCD Interfacing

• The Arduino Code and its simulation file have been added in the zip format that you have downloaded at the start.
• Use that simulation but the best way is to design your own simulation that will assist you to learn better along the process.
• Next, Arduino Mega 2560 Board is interfaced with a 20x4 LCD.
• Design the circuit given below to interface LCD with the Arduino Mega 2560 board:

• Data pins of LCD are connected with 8,9,10 & 11 pins of Arduino Mega 2560, while Pins 12 & 13 of Arduino board are connected to Enable & Reset of LCD.
• To upload the code, compile the Arduino code available in the zip format and get the Hex file.

• You will use Arduino Mega 2560 properties panel to upload the hex file as we excercised in the previous section.
• You have successfully interfaced LCD with the Arduino Mega 2560 board, now press the RUN button to get the result shown in the below figure:

Summary

• First, you need to download the Arduino Mega 2560 Library Files.
• Next, copy these files from “Proteus Library Files”(Folder) to the Library folder of Proteus software.
• Now, look for the Arduino Mega 2560 in Proteus software.
• Place that Arduino Mega 2560 board in the proteus workspace.
• Next, double click the board that will return the properties panel and upload the HEX File.
• Design your circuit & run the simulation.

That’s all for today. Hope you’ve enjoyed reading this article. If you’re unsure or have any questions, you can pop your comment in the section below. I’m willing to help you the best way I can. Feel free to share your valuable feedback and suggestions around the content we share. They help us create quality content tailored to your exact needs and requirements. Thank you for reading the article.

What is IGBT? Full Form, Pinout, Meaning, Symbol & Working

Hi Guys! Hope you’re well. In this post today, we’ll cover What is IGBT? We’ll also discuss IGBT Full Form, Pinout, Meaning, Symbol & Working.

BJT (bipolar junction transistor) and MOSFETs (metal-oxide-semiconductor field-effect transistor) are commonly used electronic switches that we’ve already studied in detail. These devices are useful when you deal with low-current applications, however, when it comes to high-current applications, these devices don’t work as expected. This is where the IGBT transistor comes in handy. This device is a combination of both BJT and MOSFET and stands fit for high-current applications. In this post, we’ll cover What is IGBT in detail. Let’s get started:

1. What is IGBT?

IGBT is a three-pin device made of semiconductor material and is used for fast-switching applications. It comes with input characteristics of the MOSFETs and output characteristics of the BJT.

IGBT Full Form

IGBT stands for Insulated Gate Bipolar Transistor.

IGBT Symbol

The following figure shows the IGBT symbol. You can see from the symbol that IGBT is a combination of both MOSFET and BJT.

IGBT Pinout

The following figure shows the IGBT Pinout.

IGBT Meaning

The Insulated Gate Bipolar Transistor comes with the insulated gate from the MOSFET at the input with the conventional bipolar transistor at the output. The emitter and collector terminals are the conduction pins of the IGBT. While the gate terminal at the input is the control terminal. The conduction is controlled by the gate terminal. The insulated gate bipolar transistor comes with current and voltage ratings similar to that of the bipolar junction transistors… when IGBT is used as a static controlled switch. But what makes IGBT a simpler device compared to BJT is the inclusion of an isolated gate terminal from the MOSFET. The IGBT consumes less power in the presence of an isolated gate terminal.

2. IGBT Working

• Like MOSFETs, IGBT is a voltage-controlled device which means the only small voltage is required at the gate terminal to initiate the conduction process. IGBT can switch current from collector to emitter terminal which means it can switch in the forward direction only.

• The following figure shows the IGBT switching circuit. In this case, a small voltage is applied at the gate terminal which results in the switching of the motor from a positive supply. The resistor is included to control the current passing through the motor.
• The graph below shows the IGBT input characteristics. It is a graph between the voltage applied at the gate terminal vs current passing through the collector terminal.

• No current will flow through the IGBT when there is no voltage applied at the gate pin. In this case, the transistor will remain turned off. However, when voltage is applied at the gate terminal, the current will remain zero for a little while. When the voltage exceeds the threshold voltage, the device will start conducting and current will flow from collector to emitter terminal.
• The graph below shows the IGBT output characteristics. This is a graph between the voltage at the collector and emitter terminals vs current passing through the collector terminal.

• This graph contains three stages. The first one is the cut-off region when there is no voltage applied at the gate terminal. At this stage, the transistor will remain turned off and there will be no current flowing through the transistor.
• When the voltage at the gate terminal increases, and if it stays below the threshold voltage, it will result in the small leakage current flowing through the device but the device will remain in the cut off region.
• However, when the applied voltage at the gate terminal exceeds the threshold voltage the device will move to the active region and in this case, a significant current will flow from collector to emitter terminal.
• At this stage, applied voltage and resulting current will be directly proportional to each other. More voltage will result in more current flow at the collector terminal.

3. IGBT Modules

IGBT is used in a range of electronic switching applications where both BJT and MOSFET fail to deliver the desired results in high current applications. This hybrid combination of two transistors features voltage-controlled characteristics like MOSFETs and conduction and switching characteristics like BJT. The IGBT devices are divided into two main types.

1. Non-Punch Through IGBT [NPT-IGBT]
2. Punch Through [PT-IGBT]

Let’s discuss them one by one.

1. Non-Punch Through IGBT [NPT-IGBT]

• These IGBTs are also called symmetrical devices. The IGBT transistors that come with an n+ buffer layer are called Punch Through-IGBT (PT-IGBT)
• They are called symmetrical devices because both reverse and forward breakdown voltages are the same in this case. They are more thermally stable and more rugged in short-circuit failure mode.

• Moreover, the changing temperature won’t have a significant effect on turn-off loss i.e. it remains unchanged with temperature. And the P-layer (collector side) is highly doped in Non-Punch Through IGBT.
• They are developed with less expensive diffusion process technology, making them ideal choices for AC circuits.  Plus, the structure of NPT ensures the bidirectional blocking capability in these devices. The N base is thick in this case.

2. Punch Through [PT-IGBT]

• These IGBTs are also called asymmetrical devices. They are called asymmetrical because here forward breakdown voltage is more than the reverse breakdown voltage.
• These devices are less thermally stable and less rugged in short-circuit failure mode. And in this case, turn-off loss is directly proportional to temperature, it increases significantly with the increase in temperature.
• These IGBTs are manufactured using an expensive N-epitaxial water process. They contain a thin N base and the PT structure comes with lower reverse blocking capability.
• They are widely used in DC circuits where the voltage support in the reverse direction is not needed by the device.

4. IGBT vs MOSFET

• Both IGBT and MOSFETs are transistors and voltage-controlled devices but they are different in terms of composition and performance.
• IGBT is composed of collector, emitter, and gate pins, whereas MOSFET, on the other hand, is made of the drain, source, and gate terminals. IGBT is better than MOSFETs in terms of performance.
• IGBT needs an extra freewheeling diode to drive the current in a reverse direction. The inclusion of this freewheeling diode makes this device the best pick for high voltage applications.

• IGBT is preferred for high voltage (more than 1000V), low frequency (Less than 20 kHz), small or narrow load or line variations; high operating temperature; low duty cycle, and, more than 5kw output power rating applications.
• MOSFET, on the other hand, is preferred for large duty cycles, wide load or line variations, high frequency (more than 200KHz), and low voltage (Less than 250V) applications.
• After the MOSFET, the IGBT is widely employed in electronic devices. The IGBT covers 27% of the power transistor market.
• The greater power gain and lower input losses of IGBT make this device preferable over both MOSFETs and BJT. You’ll find high-voltage and high-current bipolar transistors in the market, but they come with one drawback.
• Their switching speed is not so good, they take time to switch the devices. Similarly, MOSFETs alone have high switching speeds, no doubt. But high-current and high-voltage MOSFET components are too expensive compared to IGBT.

5. IGBT Inverter

The IGBT transistors are employed in VFD (variable frequency drive) inverter modules as the high power electronic switch due to the following reasons.

• It carries a high current-carrying capacity. Some IGBT devices come with a maximum rated collector current Ic (max) of around 100A. And if this fails to meet the requirement, two or more IGBTs can be combined to meet the purpose.
• IGBTs come with the open circuit rated collector voltage up to 1.6kV. This explains there are devices preferable for functions off rectified three and single phase mains… ranging from 110Vac to 690Vac.

• An IGBT contains a high impedance gate terminal which projects it is technically simple to control the device by controlling the gate terminal.

 

• The low conduction losses of the IGBT ensure a low on-state voltage.
• Recall, the IGBT carries a fast switching speed. This means you can achieve high switching frequencies with reduced switching losses that play a key role in motor noise and harmonic reduction.
• The IGBT carries a wide Reverse Bias Safe Operating Area (RBSOA) that explains it is comparatively secured against load short circuits.

Know that the properties mentioned above may affect each other. An IGBT, for example, often comes with a very fast switching speed that guarantees higher on-state saturation voltage - that is a property of the manufacturing method. So this sets the trade-off between conduction losses and switching losses. This explains that for a large high-power VFD, you may require to pick slower devices with quite low saturation voltage, to minimize the total losses. Moreover, you can reduce switching losses by working with a lower modulation frequency.

6. IGBT Applications

The combination of high switching speed like MOSFETs and low conduction loss like BJT will result in developing the optimal solid-state of IGBT, making it a suitable pick for a range of applications. The following are the IGBT applications.

• Used in AC and DC motor drives
• Employed in Unregulated Power Supply (UPS)
• Used in Switch Mode Power Supplies (SMPS)
• Used in electric cars and plasma physics
• Employed in traction motor control and induction heating
• Incorporated in inverters, converters, and power supplies

That’s all for today. Hope you find this article helpful. If you have any questions, you can pop your comment in the section below. I’m happy and willing to assist you the best way I can. Feel free to share your valuable suggestions and feedback around the content we share so we keep coming back with quality content tailored to your needs and requirements. Thank you for reading the article.

2SC2240 Datasheet, Pinout, Power Ratings, Equivalents & Applications

Hello Everyone! Happy to see you around. In this post today, we’ll cover the 2SC2240 NPN Transistor. We will have a look at the 2SC2240 Datasheet, Pinout, Power Ratings, Equivalents & Applications.

Electrons are the majority charge carriers in this NPN transistor, in contrast to PNP transistors, where holes are the majority carriers. The 2SC2240 comes with a power dissipation of 0.3W, the amount of energy this transistor dissipates while operating in the forward-biased state, while the collector current is 0.1A means it can support load up to 0.1A.

This NPN transistor contains 3 terminals, named:

1. Emitter
2. Collector
3. Base

If the voltage at the base terminal is above 0.7V, the transistor will get forward-biased and the current will start flowing from Collector to Emitter terminal. If the base voltage is less than 0.7V, it will remain reverse-biased.

So, let's have a look at the 2SC2240 NPN Transistor in detail. Let’s get started:

2SC2240 NPN Transistor

• The 2SC2240 is a bipolar junction transistor that belongs to the NPN transistor family.
• This component is mainly used for switching and amplification purposes and comes in a TO-92 package.
• 2SC2240 comes with three layers, with one p-doped layer between two n-doped layers.
• The two n-doped layers represent the Collector and Emitter, while the p-doped layer represents the Base Terminal.

• This device contains three terminals: the base, collector, and emitter. The collector terminal collects the electrons coming from the base side and the emitter terminal emits the electrons into the base terminal.
• The NPN transistors contain two junctions known as collector-base junction and emitter-base junction.
• The transistor is said to operate in a Forward-Biased state, when the collector-base junction is reverse-biased, while the emitter-base junction is forward-biased.
• When a negative voltage is applied at the emitter side and a positive voltage is available at the base terminal then we can make the emitter-base junction forward biased.

NPN vs. PNP: A Quick Recall

• Bipolar Junction Transistors(BJTs) are categorized into two types i.e. NPN transistors and PNP transistors. This is a bipolar transistor, which means both electrons and holes play a role in the conductivity process inside the transistor.
• But electrons are the major carriers in NPN transistors while in the case of PNP transistors, holes are the major carriers.
• NPN transistors are preferred over PNP transistors because the mobility of electrons is more efficient than the mobility of holes.
• These bipolar devices are called current-controlled devices, in opposition to MOSFETs, which are called voltage-controlled devices and carry terminals like a drain, source, and gate.

2SC2240 Datasheet

It’s wise to go through the 2SC2240 datasheet before you apply this device to your electrical project.

2SC2240 Pinout

The following figure shows the 2SC2240 pinout.

This component contains three terminals named: 1: Emitter 2: Collector 3: Base

• These terminals differ in terms of size and doping concentration and are used for external connection with the electronic circuit. The emitter side is highly doped and the base side is lightly doped and the collector terminal is moderately doped.
• The collector terminal dissipates more energy compared to the other two terminals. It is bigger in size compared to base and emitter terminals. The large surface area of the collector side guarantees more heat dissipation.

2SC2240 Working Principle

The base is responsible for the transistor action. When voltage is applied at the base terminal, it will bias the device and as a result, the current will flow from collector to emitter terminal. As this is an NPN transistor so here current will flow from the collector to the emitter side and in the case of the PNP transistor current will flow from the emitter to the collector side. These bipolar devices are not symmetrical in nature. This projects if we exchange the emitter and collector pins then these terminals will start working in reverse active mode and will stop working in forward active mode. The different doping concentrations of these pins are the reason this device lack symmetry.

2SC2240 Power Ratings

The following table shows the 2SC2240 power ratings.

Absolute Maximum Ratings of 2SC2240
Pin No.	Pin Description	Pin Name
1	Collector-emitter voltage	120V
2	Collector-base voltage	120V
3	Base-emitter voltage	5V
4	Collector current	0.1A
5	Power dissipation	0.3W
6	Current gain	200 to 700
7	Operating and storage junction temperature range	-55 to 125C

• If these ratings are applied more than the required time, they can affect the device reliability.
• The collector-current is 0.1A which defines the amount of load this component can support.
• The power dissipation is 0.3W which represents the amount of energy released during the working of this component.
• The current gain ranges from 200 to 700 which is the amount of current this device can amplify.
• The operating and storage junction temperature ranges from -55 to 125C.
• The emitter-base voltage is 5V represents the voltage required to bias this component. The collector-base voltage and collector-emitter voltage both are 120V.
• When using this device, make sure these ratings don’t exceed the absolute maximum ratings else they can damage the device.

2SC2240 Equivalents

The following are the 2SC2240 equivalents.

• 2SC3201
• 2SC3245A
• 2SC3200
• 2SC3245
• 2SC2459
• KTC3200

Before applying alternatives into your projects, double-check the pinout of these equivalents as the pinout of 2SC2240 might differ from the pinout of the alternatives. The 2SA970 is a complementary PNP transistor to the 2SC2240.

2SC2240 Applications

The following are the 2SC2240 applications.

• Incorporated in modern electronic circuits.
• Used in Bistable and Astable multivibrators circuit.
• Used in voltage regulator circuits.
• Used in a common power amplifier.

• Used in electronic Ballasts.
• Used in energy-saving lights.
• Employed to support loads under 0.1A.
• Used in the high switching power supply.
• Used in high-frequency power transform.

2SC2240 Physical Dimensions

The following diagram shows the 2SC2240 physical dimensions.

With physical dimensions, you can evaluate the space required for this device in the electrical project.

That’s all for today. Hope you find this article helpful. Feel free to share your valuable feedback and suggestions around the content we share. They help us produce quality content based on your needs and requirements. If you’re unsure or have any questions, you can approach men in the section below. I’m happy and ready to help you the best way I can. Thank you for reading this post.