Proteus : An Introduction

Image Source: labcenter.com

Couple of years ago, one would need a strong imagination power to think of a magical tool that could run electrical systems without actual requirement or installation of any electrical component. Who had ever thought that one can design not only a network, it may be an integrated system or a tiny school project, but also can witness the system responses in real time in his laptop or mobile screen! Yes, I’m talking about the virtual simulation.

A sudden breakthrough came in the studies of electrical engineering with the development of a number of simulation software with different features. This allowed the students to develop their circuit designing skill as well as the better understanding of the system responses through real time simulations. And the very first name we have to take is ‘Proteus Design Suite’

What does Proteus offer?
Proteus comes with three major blocks of operation;

· Schematic Capture: It allows the users to design circuits using different components. Proteus provides a very user friendly schematic editor with numerous tools.

· Real Time Simulation: This is the most fascinating feature of simulation software. A user can access the simulation during run time, can do modification etc.

· PCB Design: Proteus has a different software package that allows users to design PCB with multiple inner layers, surface mount & ‘through hole’ technology. Also, one can customize PCB package for any component. 3D visualization of the PCB and 2D drawings are also included in Proteus.

Need To Know!

ISIS : It is the software package installed in Proteus for schematic capture and real time simulation of the network. ISIS is enriched with a huge built in component library. Again one can add libraries of external components. These libraries come with the PCB package of the components with standard measurements. Also the PCB package can be customized manually. 

Image Source: electronics Lovers

ARES : PCB designing and related tools come under this ARES software package. Schematic drawn in ISIS, can be transferred directly in ARES.

Image Source: 201tube.tv

Designing PCB in Proteus ARES can be a good option for beginners. There are dedicated software for PCB designing with upgraded features. Still Proteus can provide a better interface to get acquainted with the basic tools and settings of PCB designing.

Read More →

Tellegen's Theorem

B.D.H. Tellegen
Image Source: edubilla.com

Tellegen’s Theorem is the very first theorem that initiates the journey of EEE. In 1952, Dutch engineer B.D.H. Tellegen proposed this theorem which goes something like this,

‘‘In any electrical network, the summation of instantaneous
 power in all the branches is equal to zero provided that the network 

satisfies Kirchhoff’s Laws’’

Eventually this theorem has become an important circuit analysis tool. But what is so special in this theorem? It simply looks like another form of energy conservation law, isn’t it?

Power Is Everything
Engineers throughout the world are much more concerned about power. Why? Let us take a device (electrical or mechanical) for example. You will see we never care about the voltage or current specifications of the device while buying. Rather we want to know the power rating or how efficient the device is. So power is an important term to define the sustainability of a system and it requires to measure power associated with each element of an electrical system.

Absorbed or Supplied?
The theorem clearly says that absorbed power has to be equal to supplied power. Here we encounter some facts;
· How to find out which element is supplying power and which one is absorbing? Is it always the source (voltage/current) that supplies power?
· How to differentiate between the absorbed power and the supplied power?

Sign Convention
It’s a general convention that current comes out from the positive terminal of active components (battery and discharging capacitor) , flows through the passive component and flows back into the negative terminal of the active component.

A simple circuit
Image credit: Engineer’s Articles

Following this convention we have,

Active Sign Convention states that if current comes out from the positive terminal of an active element, power is being supplied to the network and it has a negative sign.

Passive Sign Convention states that if current enters into the positive terminal of a passive element, power is being absorbed by that element and it has a positive sign.

Sign Convention
Image Source: Basic Engineering Circuit Analysis by J.D. Irwin

Throughout the calculation, sign of power will vary according to the current direction and the sign of the component’s terminal. But the question is, does a passive element (i.e. resistor) have specified positive or negative terminals?  Think it yourself.

Network Solving
It is very simple to solve electrical network using Tellegen’s Theorem. We just need to find the values of branch voltages and current through the element. Using appropriate sign of powers, this theorem can be verified and circuit can be solved for unknown parameters.

Another question remains; why is this theorem so important? Apart from solving electrical networks, Tellegen’s theorem is used for filter designing in digital signal processing; in areas of biological & chemical processes; in determining the stability of complex systems.

Read More →

Seven Segment Display (SSD)

Displays always add an extra attraction to any project. And when it comes about representing numerals, seven segment displays are the most preferred over other types of displays. Basically it’s nothing but a combination of 7 LEDs which gives the 10 numerals (0-9) & some alphabets (A/a, B/b, C/c, D/d, E/e, F/f). Okayy, this may be more than enough for introduction. Let’s try to dive into this tiny thing for some more details.

Why All These?

It’s true that working with these devices practically, is a more convenient way to learn than reading articles on them. But knowing what’s going inside them may give a better understanding that can help in modifying them for developed projects.

What’s Inside?
It’s evident from the name that the 7 ‘Segments’ indicate 7 LEDs with an additional LED. This additional LED serves the purpose of decimal point (DP). As LED’s are basically diodes, a two terminal device, they can be powered up with respect to either of the terminals. Depending on this, we find two variants of SSD;

· Common Anode Display (CAD) or Common Vcc [All the anodes are shorted inside]

· Common Cathode Display (CCD) or Common ground [All the cathodes are shorted inside]

Image source: circuitdigest.com

Physically 10 pins are visible from outside among them 8 are data pins and two are marked as ‘COM’. Com pins are basically the shorted anodes or cathodes and either of them needs to be connected with the source (Vcc/GND). The pins & LEDs are categorized using alphabets.

Image Source: Parallax.com

Working Principles
Being a digital component, SSD needs digital pulses for functioning. So it’s very simple. We just need to send pulses to the LEDs that we want to turn on. For example, if we want to show 7 on the SSD, the values we need to assign are,

a	1
b	1
c	1
d	0
e	0
f	0
g	0
DP	0

SSD can be interfaced with numerous development boards like Arduino, Raspberry Pi or PID Microcontroller. Again there is a dedicated decoder IC to drive SSD known as BCD to seven segment decoder or IC-7447.

Arduino Interface
We need to connect the 8 data pins of SSD to 8 digital pins and the COM pin to the source or GND. For showing a specific number, we just need to high the state of the required pins of the Arduino. But if we want to make a sequence of numbers, the code has to be modified according to the requirement of the project.

Arduino Interface
Image Credit: Engineer’s Articles

7447 Decoder IC Interface
Here we just need an external circuitry to convert the decimal numbers into BCD (10 to 4 line encoder). 7447 Decoder IC will convert them digital pulses and the number is visible in the SSD.

 Image Credit: Engineer’s Articles

Now, there exist a number of modules that provide reduced data pins, multiple SSDs on one board with many more advanced modifications. But the basic working function is same and it has made the SSD one of the simplest and most preferred digital displays that is widely used in calculators, digital watch, microwave oven, electric meters etc.

Throughout the blog, have you noticed the unique feature of this display? SSD can represent 0-9 & A, B, C, D, E, F; a complete unit of hexadecimal number system. Interesting, isn’t it?   

Read More →

EEE Tree: A Journey of Courses

Electrical & Electronic Engineering, being one of the most versatile fields in engineering, attracts many juveniles each year to choose it as their career. Surprisingly not all end up as an engineer although they go through the same courses and fight for a piece of paper to define himself as an engineer!

No Time for Realization?
What is the difference between an electrical engineer and an electrician? Have you ever come across this question or have wondered about it, seeing an electrician work? Many of you may have. The answer is pretty simple when google is around. But let's halt for a moment and think whether we can answer this question based on the engineering courses we have learned so or should I say, we have 'Passed'?

Precisely speaking, we go through about 40-50 courses in BSc but if we try to recall, we may see that most of us never realized what is the motive of learning a specific course. At least once in tour life you have wondered why you are learning this Math, Mechanical or Civil course in EEE. Applications of a course is not confined to a specific sector. Rather they are vastly distributed and interrelated with each other. Let's try to have a look at the basic applications of the core courses of EEE.

Basic blocks of EEE

Image Credit: Engineer's Articles

Generation of Electrical Power
Following the chronological order, we need to generate electrical power first, but how?

Mechanical courses describe the process of generating

electrical power from natural resources. To be precise, mechanical

devices converts the natural energies to electrical energies

In addition, a mechanical drawing course is offered to give basic ideas about engineering drawing of objects and shapes from different angles and views. Again, we find two fundamental Energy Conversion courses where in the first part, Energy Conversion I, DC machines (Motors, Generators) and the transformer operations are introduced. And Energy Conversion II, the latter one, is concerned about AC machinery fundamentals.

Now why should we concern about machines? There are mechanical engineers for that purpose. But as an EEE engineer working in a generating station, one must need to know these things to operate the electrical system in accordance with the unpredictable situations.

Transmission of Electrical Power

The next approach to reach consumer is to transmit the generated power from a very long distance. Two core courses Power System I & Power System II are offered to give a basic idea to understand the structure of a typical power system.

The designing of a transmission system including the selection of cables, towers, sag, system protection, fault analysis and high voltage occurrences like line inductance, capacitance, corona etc. are the selected topics. Necessary computational techniques (per unit, phasor) are taught to analyze a system.

Distribution & Supply

Substations serve the purpose of receiving the transmitted power and distribute it through the networks. An engineer must be well aware of the maintenance, operating system and protection of the substation consisting of transformers, switches, relays, current transformers, isolator, control desk, fuse, circuit breaker etc. 

Again a designer has to design the distribution network as per the requirement of the area for efficient distribution of electric power.

To provide these concepts with necessary computational and designing problems, Power Electronics, Switchgear & Protection, Power system and Energy Conversion courses are offered.

Image Credit: Engineer's Articles

Fundamentals

Coming to the very first and fundamental course, we find Electrical Circuit I that initiates the journey of EEE. With Electrical Circuit II, these two courses provide the circuit laws & theorems, properties of electrical elements, circuit behavior and responses under different excitations. These give the basic of circuit designing, fault analysis, AC & DC transients and filter designing.
Again, magnetic circuits for relays & electromagnetics and coupling circuits for transformers are introduced.
The prior motive of these courses are to develop the ability of electrical system designing and system fault analysis. Two other basic courses in this regard are, Civil Engineering Drawing and Electrical Services Design.

Civil drawing introduces the infrastructural design of houses and

buildings with different engineering notations and design rules.

Electrical Services Design teaches the installation of electrical system in

the infrastructure with relevant domestic & industrial system installations.

It was in the nineteenth century when EEE witnessed the technological advancement. Revolutionary communication hacks and the invention of integrated circuit technology resulted into two major branches of EEE; Communication and Electronics.

Image Credit: Engineer's Articles

Engineering Physics & Solid State Devices

Generally two physics courses are offered to the EEE students on the following topics;

· Atomic Structure of materials

· Electronic Structure of materials

· Waves & Oscillations with mechanics

· Electrostatics & Magnetism

· Modern Physics

· Optics

To many of us, these physics courses are the most painful courses with numerous awful derivations and equations. Still the courses are very much important to understand the material properties that lead to some sophisticated sectors like VLSI, Photonics, Optoelectronics and Embedded systems.

Why This Course!

The next course in this queue is the Solid State Devices or Semiconductor Physics, the very course we mostly want to 'Pass'rather than to learn and try to find the answer why we are learning these things! However this course is the continuation of the electronic structure of materials (semiconductor) that includes the inherent properties like conductivity, resistivity, optical properties, temperature dependence and operating principles of semiconductor devices based on the Schrodinger's Wave Equation. This is course is the introduction to the high level integration technology, embedded system, chip designing and fabrication etc.

The prime motive of this course is to develop mathematical

models of the physical phenomena taking place at the electronic level

of materials. It describes the physical properties in terms of equations

used in Electronics I

Electronics

The primary goal of Electronics I is to get yourself acquainted with the basic semiconductor devices' (Diode, BJT, FET) structures and their operating principles. Though the advanced technologies use FPGA, MOSFET, CMOS, the fundamental principle is almost same. Electronics I provides the necessary analysis techniques and equivalent circuit models.

Electronics II is about analog electronic devices (Operational Amplifiers), circuitry and operations. Discussions on filter designing, frequency responses and classes of power amplifiers provide the basic ideas on the analog integration and system analysis.

Unlike Electronics I & Electronics II, Digital Electronics or Digital Logic Design (DLD) deals with the principles of latest integrated devices (Digital devices). Enhancing the ability to understand and to develop the digital circuit blocks with SSI & MSI is the prime motive of this course. Semester projects like building a specific base calculator gives practical understanding of this course. 

Communication

Communication I briefly discusses about the sequential development of communication methods and different technologies while Communication II talks about signal characteristics and occurrences. These two compact courses give the basics of further applications like optical, microwave, cellular and wireless communication.

Signals

There are some courses to discuss the properties and behavior of signals which are electromagnetic waves in most cases. Electromagnetic Fields & Waves provides the basic knowledge about electrostatics, magnetostatics and wave propagation.

Digital Signal Processing (DSP) and Signals & Systems, these two courses discuss various kinds of signals and their analysis techniques both in time and frequency domain in details. These two courses lead to the advanced signaling applications.

Interdisciplinary: Why Programming?

Though programming is centered to CSE, it has drawn significant attention in EEE also. That's why a significant sector, Electrical & Computer Engineering (ECE) has arisen. And sometimes EEE students are found to be programming freaks. Following that, basic programming courses are offered so that students can have a handy experience on C, C++,

Image source: Pond5.com

Python, Assembly and MATLAB programming. These programming languages are very much crucial to PID, Micro-controller based system, development boards (Arduino, Raspberry Pi) and design related projects and courses.

Miscellaneous

There are always fundamental mathematics courses to provide sufficient knowledge on basic analytic techniques like Differential Calculus, Integral Calculus, Matrices, Vectors, Linear Algebra, Laplace Transformation etc. to analyze and solve different problems in engineering.

Math courses are crucial to engineering as engineering is an

applicative subject, not theoretical. Mathematics has become the 

language of engineering that one must know.

Again there are number of optional courses to provide detailed and advanced discussions on a particular topic. And the engineering courses with corresponding practical courses and simulation software skills add a compact concept to the journey of EEE. 

Read More →