Tuesday, July 31, 2012

Parabolic antenna

Parabolic Antenna
        A parabolic antenna is an antenna that uses a parabolic reflector, a curved surface with the cross-sectional shape of a parabola, to direct the radio waves. The most common form is shaped like a dish and is popularly called a dish antenna or parabolic dish. The main advantage of a parabolic antenna is that it is highly directive; it functions similarly to a searchlight or flashlight reflector to direct the radio waves in a narrow beam, or receive radio waves from one particular direction only. Parabolic antennas have some of the highest gains, that is they can produce the narrowest beam width angles, of any antenna type.Parabolic antennas are used as high-gain antennas for point-to-point communication, in applications such as microwave relay links that carry telephone and television signals between nearby cities, wireless WAN/LAN links for data communications, satellite and spacecraft communication antennas, and radio telescopes. Their other large use is in radar antennas, which need to emit a narrow beam of radio waves to locate objects like ships and airplanes.

Parabolic antenna at transmitter section

At the transmitter section the operating principle of a parabolic antenna is that a point source of radio waves at the focal point in front of a paraboloidal reflector of conductive material will be reflected into a collimated plane wave beam along the axis of the reflector.
Parabolic antenna at receiver section

At the receiver section an incoming plane wave parallel to the axis will be focused to a point at the focal point.

Monday, July 30, 2012

How DVD player works?

Disc drive mechanism:

It consist of a motor which drives the disc in circular motion.Also contains a disc feed-a loading tray that is used to accept the CD.Thus the entire disc rotates.The spindle is held in its position with the help of small gears and belts that are attached internally. Some players have an automatic feed system in which, there will be no tray. Instead the disc will be automatically recognized after inserting a part of it.

Optical system: 

The optical system mainly consists of the laser beam, lenses, prism, photo-detectors and also mirrors. The output of this mechanism will be the input for the disc-drive. The laser beam will be a red laser diode which works at a wavelength of 600 nanometers. The optical system also requires a motor to drive it. The laser system and photo-detector is placed together on a single platform. The laser diode as well as other diodes is made with the help of glass.


The PCB is similar to that of any other electronic circuits. The electronic outline must be drawn on the PCB with the correct placement of all the IC’s resistors as well as capacitors. After the outline has been drawn, the components must be soldered to their respective places. All this must be done in a very clean environment so that the board does not become contaminated by dust. All the primary components of the electronic circuit should be made out of silicon.

The pits and bumps in the DVD are hit by the laser from the optical mechanism of the DVD player. This laser will be reflected differently according to the change of pits and bumps. Though the laser hits a single spot, the DVD moves in a circular motion so that the entire area is covered. Mirrors are also used to change the spot.
These reflected laser beams are then collected by a light sensor (eg. photo-detector) which converts the different signals into a binary code. In short, the optical system helps in converting the data from the DVD into a digital code.

Hardwork Can Never Ever Fails..
Best Luck..

ipod Hardware

What is there inside ipod?


Primary Components:

  • Hard drive
  • Battery
  • Click Wheel
  • Display
  • Microprocessor
  • Video chip
  • Audio chip  

Mother board:

 Hardwork Can never Ever Fails...
Best Luck...

How Opto Coupler works? Animation

What is opto coupler?

 An opto-coupler is an optical link and it connects two circuits via this link.
The optical link is contained within a chip. A Light Emitting Diode inside the chip shines on a photo-diode, photo-transistor or other photo device. When the photo device sees illumination, the resistance between its terminals reduces. This reduced resistance can activate another circuit.  

Other Names: 



 The LED requires 1mA to 15mA.

What does this mean?

If the current-limiting resistor connected to the LED has a high value, only a small current will flow through the LED and it will not glow very brightly. (The LED is inside the chip - you cannot see it).
The transistor will not turn on very much and the resistance between the collector-emitter terminals will be fairly HIGH. The output voltage will remain fairly HIGH.
As the current through the LED increases, (the current-limiting resistor is reduced in value) the LED will glow brighter and the transistor will turn on harder. The output voltage in the diagram above will reduce.
If the current through the LED is allowed to rise and fall, the output voltage of the circuit above will fall and rise. In this way the opto-coupler will pass AUDIO.
If the current through the LED changes instantly from zero to say 15mA, the output will change from HIGH to LOW. This is the principle of SWITCHING or passing a DIGITAL SIGNAL

Hardwork Can Never Ever Fails...
Best luck...


Saturday, July 28, 2012

Physics Tutorial

A nice collection of study materials for Basic Physics with animations, illustrations and explanations are available at the below link.

CLICK HERE to view the website.

I hope it will be very useful for everyone to study the fundamentals thoroughly....

How Cathode ray Tube works? Animation

The cathode-ray tube (CRT) is one of the main elements of an oscilloscope. The tubes are produced with electrostatic and electromagnetic control, where electrostatic or magnetic fields deviate the electron beam respectively. Animation shows the principle scheme of CRT with electrostatic control as well as the motion of the electrons in the beam drawing a sinusoid on the screen of oscilloscope.

CRT consists of the glass bulb evacuated to a high vacuum, the cathode (a source of electrons), cathode heater, electrodes for brightness and focus control, several accelerating anodes, the pairs of horizontal and vertical capacitor plates deviating the electron beam, and fluorescing screen. One of anodes, which accelerate the electrons, is placed close to the screen. The high positive voltage is applied to this electrode. Under the action of the applied voltage the electrons are moved with acceleration from cathode to anode. In the absence of the voltage applied to deviating plates of the capacitor the electron beam will be incident on the screen in the center brightening a point in the fluorescing layer.

 In oscilloscope the analyzed signal after amplification is applied to vertical deviating plates, while the periodic sawtooth signal is applied to horizontal plates. As a result the electron beam "draws" the dependence of the investigated signal on time on the screen of the tube. Reaching the right side of the screen the beam has to be returned to an initial point at the left side.

Thus, if CRT is not blanked during this retrace, then the beam will leave a track crossing the image of investigated signal. For this reason, during retrace a negative voltage is applied to control electrode situated near to cathode and electrons are locked by such a way at the electron gun. As a result, the electron beam will be discontinuous, as shown in animation.

Fig: CRT 

Hardwork Can Never Ever Fails..
Best Luck...

Batteries in series and parallel

What happens when we connect the batteries in series and parallel?

When we connect the Batteries in Series, we will get sum of voltages of both the Batteries.
Here we can see that, among the 6 electron bags, 3 is provided by one 3V battery and another 3 is provided by the other Battery.
Fig: Batteries series

When we connect the Batteries in Parallel, we get the same voltage, but sum of the currents.
Here we can see that, both the batteries are contributing Energy bags to the bulb. We can observe that both the batteries are providing only 3 energy bags.

Fig: Batteries paralle

(Courtesy: www.dynamicscience.com)

Broadband Double-Ridged Horn Antenna

Horns are widely used antennas since they have a simple construction, are easy to excite and have a large gain. They are employed for example as feed elements in satellite tracking systems or communication dishes and they serve as a standard antenna for calibration and gain measurements. Since they have a limited bandwidth, great efforts have been made to enlarge the operational bandwidth. Ridges on the side flares are introduced to extend the bandwidth, similar to the ridges in a waveguide that lower the cut-off frequency. The design of double-ridged horn antennas reaches back to the late 1950s. Figures 1 and 2 show a 3D view
 of the horn that we simulated.

Fig: Tilted front 3D view of the antenna model. 1: Feed section, 2: Ridge, 3: Wedge, 4: Lower flare, 5: Upper flare, 6: Copper strap.

Fig:  Feeding section of the double-ridged horn antenna. 1: Ridge, 2: Cavity, 3: Coaxial feed, 4: Source plane, 5: Port plane. Wedges and other parts are removed for better visualization.

The propagation of the electric field is shown at two different frequencies (ramped sinusoidal excitation) in the following movies.

      Fig:  Magnitude of the electric near-field at 7 GHz. 
Fig:  Magnitude of the electric near-field at 12 GHz. 

Friday, July 27, 2012

How lithium Ion Battery works?

The three primary functional components of a lithium-ion battery are the negative electrode, positive electrode, and the electrolyte. The negative electrode of a conventional lithium-ion cell is made from carbon. The positive electrode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent. The electrochemical roles of the electrodes change between anode and cathode, depending on the direction of current flow through the cell.

During discharge, lithium ions Li+ carry the current from the negative to the positive electrode, through the non-aqueous electrolyte .

Fig: Working of Lithium Ion Battery

During charging, an external electrical power source (the charging circuit) applies an over-voltage (a higher voltage but of the same polarity) than that produced by the battery, forcing the current to pass in the reverse direction. The lithium ions then migrate from the positive to the negative electrode, where they become embedded in the porous electrode material in a process known as intercalation

How Solar Cells works? Animation

Fig: Working of Solar Cells

Photons strike special molecules in the Photovoltaic cell. Electrons in these molecules absorb the energy form the photon fly off the molecule and down and electric circuit following a path in an electric field that forces them to travel from positive to negative.

Along the way the circuit takes electrons through different electronic devices where their energy is used or through batteries where the energy is converted into chemical energy and stored.

Since electrons travel in a circuit they eventually return to the group of atoms from which they were lost. An electron doesn't return to the exact atom from which it was lost but will return to an atom in the group of atoms which lost their electron.

(Courtesy: www.dynamicscience.com)

Actually what is Alternating Current?

Fig: Alternating Current

When we plug some electrical equipment to the Wall Socket, what is happening?
What the Power Houses are selling to us?
Are they selling electrons or just Energy?

The type of current that is provided by generators is called alternating current(ac).

The electrons in the circuit do not move in any direction but simply vibrate about a fixed point. The energy from the outlet causes the electrons, already in the circuit or lamp filament, to vibrate.

So in general, the Power Stations sell energy to us not electrons. We supply the electrons.
When we buy a piece of wire from the Hardware store what we actually by is the supply of electrons that will be placed in our circuit. "Wire" is another name for electron source. 

Some people think that the electrons are travelling from the Power house to our House and then to the equipment. Actually, this is not true.

Look at the animation on the right and notice how the electrons do not move in any particular direction but move to and fro about a fixed point.

(Courtesy: www.dynamicscience.com)

How transformer works? Animation

Fig: Transformer Working

A transformer is based on the fact that when an AC current flows through a wire, it generates a magnetic field commonly known as a "magnetic flux" all around it. The strength of this magnetic field is directly related to the size of the electric current and is known as the magnetic flux density. So the bigger the current the greater the magnetic flux density.

Now if another wire comes close to a wire with an AC current flowing through it , it to will experience an electric current flowing through it.

So if we put a second coil of wire next to the first one, and send a fluctuating electric current into the first coil, we will create an electric current and voltage in the second wire.

The current in the first coil is usually called the primary current and the current in the second wire is known as the secondary current.

In actual fact what happens is an electric current is passed through empty space from one coil, the primary coil, of wire to another, the secondary coil. This is calledelectromagnetic induction because the current in the first coil induces a current in the second coil.

Fig: Generation of Flux in Transformer coil

(Courtesy: www.dynamicscience.com)

How Lightning occurs?

Lightning occurs when static charges in the clouds flow to other clouds or to the ground.

Fig: Physics of Lightning

Storm clouds contain ice particles. These ice particles rub against each other and lose electrons. As the particles lose electrons they become charged. These charged ice particles accumulate and develop huge areas of charge within the cloud. The charge in these areas builds up until it eventually discharges into other areas of opposite charge or to the ground. As the charges move through the air they heat the air molecules causing the air to glow(lightning). As the air heats up it expands and creates the mighty roar of thunder that we hear after every lightning bolt.

Current and Voltage- Simplified

Fig: Current and Voltage analogy

The animation above shows miniature trucks carrying bags of energy from the battery to a light globe. The light globe takes the bags of energy and uses this energy to glow.

When returning to the battery the trucks have no more bags of energy. Each truck has lost 6 bags of energy as it moves through the light globe.

Now consider each truck to be an electron carrying energy or voltage given to it by the battery. The flow of trucks, or electrons, along the road is called a current.

Fig: Series connection

Suppose we forced each truck, electron, to carry energy through two light globes as pictured on the right. The energy is now shared amongst the light globes. Each light globe gets a share of the energy. At the end of its journey each truck has no more energy.

Notice how trucks entering the first light globe carry 6 bags of energy while the trucks leaving the light globe have only three. There is a difference of 3 bags of energy. We say there is apotential difference of 3 volts across the terminals of the light globe.

This is Series Connection of Load.

Fig: Parallel connection

Now, connect the Bulbs in parallel. We can see that the Trucks are entering to both the Bulbs parallel and emptying all the 6 bags or electrons.

This means that the potential difference across both the Bulbs are the same, as they are connected parallel. However, the number of trucks entering into each road is reduced. That means, here the current is shared.

This is called Parallel Connection of Load in an Electrical circuit.

(Courtesy: www.dynamicscience.com)

Current and Voltage Basics through animations!!!

Here is a fantastic tutorial to learn what is Current and Voltage...
Another awesome animation.

Please CLICK HERE to view the animations.

Lorentz force - application - speaker

Lorentz force

The Lorentz force is the force on a point charge due to electromagnetic fields .

click below this link


Speed Vs Time diagram

click below to see this animation


Radiation Profile

    Radiation profile (angular dependence of the Poynting flux = directivity) can be varied by a suitable choice of the number of antennas in an array and the phase angle between neighbouring radiation fields. The direction of radiation beam can be rotated electronically without physically rotating the array.  The first animation shows radiation profile of 4-antenna array with equal spacing of half wavelength. Rotation of the radiation pattern is controlled by the phase angle phi.
    N = 4, d = lambda/2
      As the number of antennas increases, the radiation profile becomes sharper. Animation below shows the case of 20- antenna array with neighbouring separation of half wavelength.
      = 20, = lambda/2

Thursday, July 26, 2012

How Piezo Electric Crystal works?

Piezo Electric Crystal Operation

(Please see the figure as per the number and read the explanation for each step.)

1. Normally, the charges in a piezoelectric crystal are exactly balanced, even if they're not symmetrically arranged.

2. The effects of the charges exactly cancel out, leaving no net charge on the crystal faces. (More specifically, the electric dipole moments—vector lines separating opposite charges—exactly cancel one another out.)

3. If you squeeze the crystal (massively exaggerated in this picture!), you force the charges out of balance.

4. Now the effects of the charges (their dipole moments) no longer cancel one another out and net positive and negative charges appear on opposite crystal faces. By squeezing the crystal, you've produced a voltage across its opposite faces—and that's piezo electricity!

(Courtesy: www.explainthatstuff.com)

Potential Energy- A funny illustration

In order to bring two like charges near each other work must be done.
In order to separate two opposite charges, work must be done.
Remember that whenever work gets done, energy changes form.

Potential Energy

As the monkey does work on the positive charge, he increases the energy of that charge.
The closer he brings it, the more electrical potential energy it has.
When he releases the charge, work gets done on the charge which changes its energy from electrical potential energy to kinetic energy.
Every time he brings the charge back, he does work on the charge.
If he brought the charge closer to the other object, it would have more electrical potential energy.
If he brought 2 or 3 charges instead of one, then he would have had to do more work so he would have created more electrical potential energy.


Difference between Level Triggered and Edge Triggered

Level Trigger:
1) The input signal is sampled when the clock signal is either HIGH or LOW.
2) It is sensitive to Glitches.
Example: Latch.

Edge Trigger:
1) The input signal is sampled at the RISING EDGE or FALLING EDGE of the clock signal.
2) It is not-sensitive to Glitches.
Example: Flipflop.

I m sure the timing diagrams below is the best way of explanation.

Hardwork Can Never Ever Fails...
Best Luck..

Courtesy: www.wiki.answers.com

What is an Operating System?

The operating system has three major functions: It coordinates and manipulates computer hardware, such as computer memory, printers, disks, keyboard, mouse, and monitor; it organizes files on a variety of storage media, such as floppy disk, hard drive, compact disc, digital video disc, and tape; and it manages hardware errors and the loss of data.

Fig: Operating System

Operating systems are either single-tasking or multitasking. The more primitive single-tasking operating systems can run only one process at a time. For instance, when the computer is printing a document, it cannot start another process or respond to new commands until the printing is completed.

All modern operating systems are multitasking and can run several processes simultaneously. In most computers, however, there is only one central processing unit (CPU; the computational and control unit of the computer), so a multitasking OS creates the illusion of several processes running simultaneously on the CPU. The most common mechanism used to create this illusion is time-slice multitasking, whereby each process is run individually for a fixed period of time.

The below diagram gives a graphical depiction of the interfaces between the operating system and the computer component.
Fig: Operating Systems Interfaces

(Courtesy: www.contrib.andrew.cmu.edu, www.comptechdoc.org)

How Micro SD card Works?

Memory Card:

The Secure Digital (SD) Card or more commonly known as memory cards are small size storage devices that are specially designed to store and transfer data from audio and video consumer electronic devices like digicam, cell phones, voice recorders etc. They are known as secure digital card because they include a copyright protection mechanism that complies with the security of the SDMI (Secure Digital Music Initiative) standards. In this mechanism, a mutual authentication and encryptions are used to protect the card content from illegal usage.

How SD Memory card works 

A commonly used memory card is shown in the above image. The notch in the tip right corner of the card helps to identify the right way of attaching with the device. As per the standards, each SD card is formatted with a File Allocation Table (FAT) file system, which allows every operating system to access the files in that system.

SD Memory Card Pins 

The SD card communicates with the host (PC/Laptop) based on an advanced nine pin interface which is designed to operate at a low voltage. The nine pins, as shown in the above image, are for Clock, Command, Data and Power.




Hardwork Can Never Ever Fails ...

Best Luck.. 


Racetrack memory is a non-volatile memory device. Racetrack would offer storage density higher than comparable solid-state memory devices like flash memory and similar to conventional disk drives and also have much higher read/write performance. It is one of a number of new technologies trying to become a universal memory in the future.

Racetrack memory uses a spin-coherent electric current to move magnetic domains along a nanoscopic permalloy wire about 200 nm across and 100 nm thick. As current is passed through the wire, the domains pass by magnetic read/write heads positioned near the wire, which alter the domains to record patterns of bits. A racetrack memory device is made up of many such wires and read/write elements.
Racetrack memory uses electrical currents to "push" a magnetic pattern through a substrate.

There are two ways to arrange racetrack memory.

1. A series of flat wires arranged in a grid with read and write heads arranged .

2. U-shaped wires arranged vertically over a grid of read/write heads on an underlying substrate. This allows the wires to be much longer without increasing its 2D area, although the need to move individual domains further along the wires before they reach the read/write heads results in slower random access times.

Oscilloscope demonstration

Click  below to view the demonstration of oscilloscope:

working Animation

Hardwork Can Never Ever Fails...
Best Luck...

Wednesday, July 25, 2012

Animation of making of CMOS Microchip

Click below to view the fantastic animation of making of microchip:


Hardwork can never ever fails...
Best luck...

How the Matrix Keypad works with a Micro controller?

Fig: Matrix Keypad when there is no Button press

The matrix is controlled by a micro-controller.
]For the above 16-button 4x4 matrix, 8 pins of the micro controller will be used.
The first 4 pins will be OUTPUTS and will be connected to the COLUMN wires, while the other 4 pins will be INPUTS and will be connected to the ROW wires.
The OUTPUTS of the micro-controller will NOT all have power at the same time.
The outputs will go high one by one in cycle.

During this time, it will also monitor the inputs for a signal. As long as all inputs are LOW , the Micro-controller will take no action.
Now, suppose that the operator presses the button 3C.

Please see the below image.

Fig: Button 3C of the Matrix Keypad is pressed

This button has connect the matrix col C, with the matrix row 3.
When the output C of the micro-controller becomes HIGH, the signal arrives also at the input 3 of the micro-controller, through the pressed button.
The micro-controller check the 4 inputs and detects that when the specific output (C) is high, there is a HIGH signal at the input 3.
So, this means that the input C3 is pressed!

OSI Reference Model

Fig: OSI Reference Model

The OSI reference model consists of seven layers that build from the wire (Physical) to the software (Application).

How Radar works?

Fig: How Radar Works?

As the radar antenna turns, it emits extremely short bursts of radio waves, called pulses. Each pulse lasts about 0.00000157 seconds , with a 0.00099843-second  "listening period" in between.
The transmitted radio waves move through the atmosphere at about the speed of light.

By recording the direction in which the antenna was pointed, the direction of the target is known as well. Generally, the better the target is at reflecting radio waves , the stronger the reflected radio waves, or echo, will be.

This information is observed within the approximately 0.001-second listening period with the process repeated up to 1,300 times per second.
By keeping track of the time it takes the radio waves to leave the antenna, hit the target, and return to the antenna, the radar can calculate the distance to the target.

(Courtesy: http://www.srh.noaa.gov)

How Power Supply Works?

Fig: How Power Supply works.

How to design a DC Power supply?
The first step of Power supply Design is Stepping Down the AC current into a lower voltage.
This is done by a Step Down Transformer.
Now we need to remove the Alternating Waves and make a DC Current from it.
For this purpose we will use a Bridge rectifier, in which the AC will be converted into DC.
Even if it is rectified, there will be some fluctuations in the output.
This can be removed by connecting a Capacitor Parallel, as it will not pass the DC and pass only the AC Current.
Thus the AC current will be bypassed through the Capacitor to the Ground and we will obtain a Direct Current signal at the output.
Now you can use this DC current for various applications.

In the image, the moving arrows shows that they are AC and constant arrows shows the DC.

Monday, July 23, 2012

Introduction to Printed Circuit Board-Animation

Electronic circuits in schools and industry are normally manufactured through the use of PCBs (Printed Circuit Boards). The boards are made from glass reinforced plastic with copper tracks in the place of wires. Components are fixed in position by drilling holes through the board, locating the components and then soldering them in place. The copper tracks link the components together forming a circuit.

The two diagrams below show the track side of a PCB (normally the underneath side) and the component side (normally the top side) of the same circuit. The relay and integrated circuit are ready to be placed in position and soldered.

Hardwork Can Never Ever Fails...
Best Luck....

Animated circuit Board

Hardwork Can Never Ever Fails..
Best Luck...

Sunday, July 22, 2012

Single Side Band suppresed Carrier-Animation


This modulation modulation was the basis for all long distance telephone communications up until the last decade. It was called "L carrier." It consisted of groups of telephone conversations modulated on upper and/or lower sidebands of contiguous suppressed carriers. The groupings and sideband orientations (USB, LSB) supported hundreds and thousands of individual telephone conversations. 

SSB was used by the U.S. Air force's Strategic Air Command (SAC) to insure reliable communications between their nuclear bombers and NORAD. In fact, before satellite communications SSB-was the only reliable form of communications with the bombers. 


 (1) Since the carrier is not transmitted, there is a reduction by 50% of the transmitted power (-3dBm).

 (2)Because in SSB, only one sideband is transmitted, there is a further reduction   by 50% in transmitted power (-3dBm (+) -3dBm = -6dBm).
(3) Finally, because only one sideband is received, the receiver's needed bandwidth is reduced by one          half--thus effectively reducing the required power by the transmitter another 50% (-3dBm (+) -3dBm (+) -3dBm = -9dBm).

Hardwork Can Never Ever fails...
Best Luck...




clipper is a device designed to prevent the output of a circuit from exceeding a predetermined voltage level without distorting the remaining part of the applied waveform.

Voltage clipping limits the voltage to a device without affecting the rest of the waveform

A clipping circuit consists of
  • linear elements like resistors,
  • non-linear elements like junction diodes or transistors.
  • It does not contain energy-storage elements like capacitors
Clipping circuits are used to select for purposes of transmission, that part of a signal wave form which lies above or below a certain reference voltage level.
A clipper circuit can remove certain portions of an arbitrary waveform near the positive or negative peaks.
Clipping Circuits are also called as Slicers, amplitude selectors or limiters.

Two shunt diode clipper circuits

Two shunt diode clipper circuits

A one or two zener diodes are used to clip the voltage VIN. In the first circuit, the voltage is clipped to the reverse breakdown voltage of the zener diode. The output voltage in the first circuit should also never be more negative than the diode's forward voltage.

In the second, the voltage in either direction is limited to the reverse breakdown voltage plus the voltage drop across one zener diode.

Clippers may be classified into two types based on the positioning of the diode.
  • Series Clippers, where the diode is in series with the load resistance, and
  • Shunt Clippers, where the diode in shunted across the load resistance.

Clippers may be classified based on the orientation of the diode.
  • Positively Biased Diode Clipper
  • Negatively Biased Diode Clipper
The signal can be clipped to between two levels by using both types of diode clippers in combination. This clipper is referred to as Combinational Diode Clipper or Two-Level Clippers

ALL THE BEST............

7 Segment Display-animation

7 Segment Display:

Hardwork Can Never Ever Fails...

Best Luck..