Tuesday 22 November 2011

LIVE TV



Now Enjoy watching Malayalam and other Television Channels live on your Mobile..



This will works in both 3G and 2G Networks.. and the main Advantage of this service is 



This is available for you With out any Monthly rental


(Data Charges May apply )


Start enjoying This Service

















Cartoon Network




Fashion Tv




People Tv




V  Channel




Pogo




Jaya Plus




High Quality Links Works Good with 3G




People Tv


Asianet News

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Maa Musiq





F.A.Q


Problem 1 : there is no such resource or the file has been removed or file expired.....


Solution : If you are using Browsers like Opera mini Or UCweb please avoid it and brows this
Page though your Default web browser of your phone.


Problem 2 : I am browsing from Computer and when I click on the LINK start streaming nothing
happens
Solution : Please assure that weather your computer contains an online player. Eg : Real player
OR
If you have VLC player Right click on Start streaming and copy link address and Open
VLC and find out it's menu for steaming(Media>> Steaming) and put this link and click
play.
Problem 2 :I am plying on phone when I try to play it says "set default access point first "
Solution :Click menu and open the real player(in s60) and
>>options>>settings>>connection>>network.>> SET YOUR WORKING SETTINGS
AS A DEFAULT ACCESS POINT ,close it and try to play tv it will surely play,,
Problem 2 :I am browsing through my phone's (default) browser when I open the site and try to play
it says "General memory full"
Solution     :If you are browsing in your phone's default browser please download uc browser
(www.ucweb.com) and then access www.techdatacare.blogspot.com and try to play TV
 

OR 


Close all other applications

Monday 21 November 2011

Malayalam mp3 Free Download

ABHIMANYU

                      1.Ramayanakatte - Abhimanyu

                       2.Kandhunjan-Abhimanyu

Antilock brake system

Antilock brake system (ABS)



The antilock brake system or the ABS control unit helps to maintain control and directional stability of an automobile in case of extreme braking circumstances. This is achieved by controlling the rotational speed of every wheel by metering the brake line pressure at the time of extreme braking. The system works on most types of road surfaces and decreases the risk of an accident and severity of an impact. Research has shown that an antilock brake system can decrease the chance of a vehicle accident by 18%. ABS brake systems were introduced in the late seventies and have enjoyed great technological advances since that time.

Not only does ABS provide non-skid functionality but it also supports electronic stability control, brake assist, traction control, etc. Recently, additional sensors have been added to the system, gyroscopic sensors and steering wheel angle sensors. Both synchronize to match the direction of the car with the direction of the steering wheel. The wheel angle sensor also helps the ABS system control the outer wheels to have a more positive braking effect when compared to the inner wheels on the curve.

PRESSURE MEASURMENT

The ABS assembly is made up of a central electronic unit, four solenoid valves and two or more electric hydraulic pumps. The function of the electric hydraulic pump is to supply brake fluid pressure to the braking system by forcing hydraulic pressure to a reservoir located in the accumulator. The four solenoid pressure valves control brake fluid pressure for each individual wheel. During an ABS operation event, one or more of the solenoid valves dump brake line pressure to a particular wheel allowing it to start turning. ach wheel has a dedicated wheel speed sensor which sends an electronic signal to the ABS controller, from this signal the rotational speed of the wheel can be determined. The location of wheel speed sensor may vary, on most vehicles the front sensor is made into the steering knuckle, near the front wheel hub or outer CV joint. In the rear of the vehicle the sensor rings are bolted to the rear driver assembly on the ring gear or attached to the outer axle flange on each side. Some even use the vehicles speedometer sensor VSS (vehicle speed sensor) to read rear wheel speed.

oday's brake systems are reliable and easy to maintain, most systems are designed for easy service and brake pad replacement. If the brake pedal becomes hard to push, there can be a possibility of a broken vacuum supply line or a failed power brake booster. It is also very important to use the correct type of brake fluid; otherwise the brake system can malfunction. This can lead to problems such as spongy feeling pedal and the brake pedal travel becoming excessive. Only the highest quality brake fluid must be used in a brake system and must never be reused and must always be discarded immediately after the fluid storage container is opened to avoid moisture contamination. When adding brake fluid to the master cylinder care must be taken make sure brake fluid is not spilled on the paint of the car, brake fluid is very corrosive and will destroy the paint.

Squealing brakes is an indication of a problem with the brake system. Most of the time a squealing noise can be a warning that the brake pads are worn down and need to be replaced. Other causes can be overheated brake pads or rotors. Sometimes rust can get impregnated on the brake lining material and cause grumbling or squeaking noises. When cleaning brake components prior to service precautions must be taken. Most brake systems contain microscopic fibers that are extremely hazardous to your health. While cleaning with brake system cleaner there is an increased chance of inhaling these fibers that accumulate on the brake components. Cleaning should be done in a well ventilated area, use an air filter respirator if possible for best results.

When the ABS system detects a problem a fault code is stored in the ABS system control unit. When an error occurs the ABS warning light located on the dashboard flashes or stays on steadily. The ABS computer stores a diagnostic code until the malfunction has been repaired. To retrieve ABS trouble codes on older vehicles can be tricky because of the variation of retrieval methods; in this case a car repair manual is needed. On newer vehicles a diagnostic information connector is located under the dash on the driver's side; a trouble code scanner can be attached to retrieve ABS codes similar to engine trouble codes.

After the problem has been repaired codes should erase automatically with no procedure from the scan tool in most cases. (Real time system) when the vehicle has been moved about 6 feet and the brake pedal has been pressed for five seconds the codes should clear. When repairs have been completed the ABS, MIL (malfunction indicator lamp) should not be illuminated, if the ABS light remains on there is still a problem, re-scan the ABS computer for further repairs.

ABS CONTROL MODULE

The ABS control module is a microprocessor that is used to manage the operation of the ABS system. The ABS control module monitors and processes information from various sensors, modulates pressure to the brake system and carries out self-diagnostic tasks. Some of the inputs to the ABS module are the wheel speed sensors, brake switch, brake warning light, parking brake switch, pressure modulation devices and ignition and power feeds. The output controls consist of brake pressure modulation components and the anti-lock brake lamp. Most ABS control modules have the ability to run self diagnostic tasks and store trouble codes for failed diagnostics. The ABS control module can display this information to a scan tool or through flash codes, via the dash mounted anti-lock brake light, making troubleshooting and repair more accessible. Some ABS control modules store sensor information when a failed diagnostic is recorded. This can assist automotive technicians in diagnosing ABS trouble codes by displaying a record of sensor information at the time of the failed diagnostic.

WHEEL SPEED SENSORS
Wheel speed sensors are used by the ABS control module to monitor wheel lock up. Wheel speed sensors consist of a toothed wheel, mounted on the wheel hub or axle shaft, so as to rotate when the wheel is in motion. A magnetic sensor is placed at a fixed location, a calibrated distance from the toothed wheel. The air gap between the toothed wheel and the magnetic sensor is usually around .040 to .060 in (refer to your auto repair book for the exact spec). When the tooth wheel rotates past the magnet on the sensor, an AC voltage is produced. The AC voltage output of the wheel speed sensor increases as the wheel speed increases. The ABS control module monitors this voltage to calculate wheel speed for ABS operation. If the ABS control module senses lower voltage from one sensor during braking, it will translate that as slower speed at that wheel and modulate brake pressure to control brake lock up.

HYDRAULIC MODULATOR

Brake lock up control is accomplished by rapidly applying and releasing the brakes of the affected wheel. To achieve this, the ABS control module is able to modulate brake hydraulic pressure to individual wheels. Brake pressure modulation is attained through several different methods. Design of the pressure modulation system varies according to vehicle design. One type of brake pressure modulator system uses solenoid operated valves to control brake pressure to individual wheels. The solenoids and valve arrangements are able to increase, hold or release brake hydraulic pressure to the brake system of a wheel. This system incorporates a hydraulic fluid pump to return fluid to the master cylinder and an accumulator to store excess brake fluid. When ABS operation is demanded, the control module operates the solenoid valves to hold or release pressure to one or all of the wheels, to control wheel lock up. A more recent design (and simpler to troubleshoot) uses high speed electric motors to seat and unseat hydraulic valves to control brake pressure during ABS stops. The electric motors are able to cycle the pressure modulation valves many times per second, to control wheel lock up. This design is less expensive to produce, since it does not require a hydraulic pump and accumulator as opposed to earlier designs.

ABS WARNING LIGHT

The ABS warning light operation is managed by the ABS control module. It is located in or near the instrument cluster and is used to warn the vehicle operator of a malfunction in the ABS system. In the event of a failure in the ABS system, the ABS warning lamp is illuminated to warn the driver. Some systems will inhibit ABS operation when the ABS lamp is illuminated. Refer to a manufacturer's manual covering your particular year/make/model automobile for the diagnostic and troubleshooting details before embarking on an auto repair project involving the ABS system.


 

Smokeless Electronic Cigarette

Smokeless Electronic Cigarette


Smokeless electronic cigarette is made up of all people 'smokers who want to but can not smoke in the community non-smoking areas, especially restaurants, cinemas, casinos and some bars. Smokeless cigarettes are supposed to be better than ordinary cigarettes because they do not absorb the emission of dangerous fumes. Smokeless electronic cigarette mean no smelly clothes, no terrible taste in Mouth and no residue in the car. Here is other smokeless electronic cigarette. The main type is the "smoke filter cigarettes, which includes a filter which prevents fumes since leaving the cigarette. These types of smokeless electronic cigarette involves the burning of tobacco and carcinogens, and therefore is worse than regular cigarettes. The old filter in this type can be replaced, and on the other hand, the large and apparently looks like a strange outcropping from the mouth. whereas smoke filter cigarettes do not emit smoke, they are still not allowed in common areas non-smoking areas.
The next is "smokeless electronic cigarette 'which does not absorb the burning of tobacco. As a substitute for cigarettes,' these 'use an electrical charge to allow smoking confidentiality. They are full of nicotine, but does not create smoke, which is why they permitted for use in non-smoking areas. But the responsible doubts about this type are that it fails to provide the correct feel of conventional cigarettes provide. The lack of smoke, large size and unique feel, makes it less attractive for many.
The third type of "steam-based mini electronic cigarettes 'is comparable with the electronic cigarette, contradictory only in the smoke characteristic. At the same time as' smoke electronic cigarettes 'may not generate smoke at all," steam-based mini electronic cigarettes' produces nontoxic water vapor , thus inspiring the conventional smoking experience. The water vapor that gives cigarettes a more normal sense without harmful smoke. A charger is used to recharge the battery in this cigarette, which consists of a cartridge containing nicotine, propylene glycol, water and tobacco flavors. Cartridges with nicotine and related variants (tobacco, apple and mint, orange, strawberry, caramel and coffee varieties) are offered. An LED is on hand at the tip, which lights up when in use. These "cigarettes" were intended to look like regular cigarettes, and is the most excellent choice for people who want to maintain smoking experience. What is more, in some areas, these cigarettes come up with cheaper than regular cigarettes. Since these cigarettes do not carry the smoke, they are permitted for use in non-smoking areas.
Companies have to move against the smokeless electronic cigarette, to help smokers stop smoking. Herbal smoke cigarettes are also available which do not have the tobacco and nicotine, and includes herbal medicine, on the way to please the tastes tactile feelings missing dependency on nicotine. The usual herbal aroma scent movements through the trachea and lungs and remove nicotine buildup in the smoker's body by removing the smoke smell. It is intended that these plant substances smokeless cigarettes can help knock desires and help smokers stop smoking everywhere. Most smokeless cigarettes may carry nicotine to provide a fix, on the other hand, they do not have the tar and chemicals on hand in the ordinary conventional cigarettes.
Smokeless electronic cigarette leaves no smoke or ash, and therefore cause little or no staining on fingers, although nicotine containing cigarettes cause yellowing teeth. None smoked stink lingers on hair and dress with this type of cigarettes. Seeing as there is no passive smoking, it compensates non-smokers. And that the fear of the smoking ban will be enforced is greatly reduced. Smokeless electronic cigarette that is supposed to be free from the 400 + carcinogens, which starts in conventional cigarettes, as a result remove the hazardous substances that cause cancer.

Sunday 20 November 2011

Microwaves And Satellite Communication

Microwaves And Satellite Communication


Micro is a unit for measuring length. As the name suggests microwaves are the portion of the electromagnetic spectrum where the wavelength is between about one millimeter and thirty centimeters that is micrometers.
Frequency of microwave bands extends from about one gigahertz to three hundred gigahertz and are useful for short range, high reliability radio and television links. Systems using microwave frequencies radar, mobile radio, satellite communications, terrestrial line of sight and tropospheric links.
An essential characteristic of microwaves is that they travel in straight lines passing through the atmosphere, is not affected by ionized layers. Again, these waves are very less affected by temperature inversions and proliferation. But these weather effects limit the distance between the transmitter and receiver to a couple of miles. This problem has been obtained by use of repeater stations placed along the propagation path that extends the distance over which communications may occur.
Basically a microwave repeater is a receiver / amplifier / transmitter combination used for relaying microwave signals over long distances and land communication links. As the frequencies of the signals thus increase the distance between repeaters decrease.
Main form of propagation in the microwave range is line of sight. Sight Line means that the transmitter and receiver must be able to see each other. Thus some sight communication depends on the height of the transmitting antennas and the nature of the terrain between them. Radio horizon limits the distance over which signals can be sent.
Microwave repeaters i.e. radio link systems carry large quantize of voice and data traffic and is subject to transmission impairments and thus reduce the distance between relay points. Majority of the radio link systems carry analog signals which is frequency modulated, while a few carry digital signals. Radio link systems, which are terrestrial are very directional and send point to point voice and data signals.
Like the television broadcast systems, including satellite radio link systems offers several path transmission of various signals. Waveguides are the main transmission media for transmission of frequencies in the microwave spectrum. The walls of the waveguides are very polished and sometimes specially plated to reduce resistance and hence power loss. These units are constructed of brass, copper or aluminum and is made in sections of various lengths. The sections are straight, bent, twisted or flexible. The most common form of waveguide is rectangular although round waveguides can be used.
Microwaves can be transmitted through common coaxial cable, micro strip, strip line and optical fiber, within certain range. Among these, transmission of light modulated signals through optical fibers is the model method. As waveguides provide excellent shielding and low loss so they can send larger amounts of power with less energy loss than co axial cables.

Switched Mode Power Supply

Switched Mode Power Supply (smps)

SMPS stands for Switched Mode Power Supply or switching-mode power supply.
SMPS is a power supply (PSU) for electronic use, which contains a switching regulator. While a linear regulator maintains the desired output voltage by spreading the excess current in a "pass" power transistor, the SMPS switches a power transistor to rapidly between saturation (full on) and cutoff (completely off) with a variable duty cycle whose average is the desired output voltage. This process gives rectangular waveform as a result which is filtered by a low-pass filter with an auxiliary coil and capacitor.
The top benefit of using this process in SMPS is that it gives a better performance. It is because of the small dispersion of power by switching transistor in the saturated and off mode compared to the semiconducting state (active region). Other benefits of Switch Mode Power Supply (SMPS) includes smaller size and lower weight which is larger in low frequency transformers which have a high weight. Furthermore, it generates less heat from the higher efficiency.
Disadvantages of SMPS

*Greater complexity
*The generation of high amplitude
*High-frequency energy, low-pass filter must block to avoid
*Electromagnetic interference (EMI)
*Ripple voltage at switching frequency and harmonic frequencies ..
*SMPS can be categorized into four types based on its input and output waveforms, as follows.
*AC in, DC out: rectifier, off-line converter input.

PORTABLE HEATER

PORTABLE HEATER

In large homes or houses without a heating system, portable stoves useful for keeping small spaces warm. Instead of providing heat to the whole house, homeowner can use a radiator in one room. Not only do these appliances save energy and money, but also spread the warm air more quickly than larger systems.
There are many choices of portable heaters. There are a wide variety available and the most expensive is not necessarily the best solution. They come in many different styles, and some even use different methods to provide heat. A buyer can make the right purchasing weigh their options before picking a machine.
Important Options
All portable heaters for indoor use is electricity. Heaters using other types of fuel must be connected to ventilation ducts so that they can not be moved. One of the benefits of purchasing an electric heater is that it can be placed in areas with an electrical outlet. Some models are designed to imitate wood stoves and combustion heaters.
There are several ways an electric heater can dissipate heat. Many have fans to blow air over hot coils and out into space. They are good at providing heat for the entire room at once. Other radiate heat from the device in the direction it faces. The user has to stay close to this type of water heater because the heat is concentrated in a small area. This form of heating is best suited to garages or other spaces that are too big to heat, but needs some heat.
Some models have additional features designed to help keep the room warm or extend functionality. Many people use thermostats that allow the user to control the amount of heat emitted by heating. Special units that already have ventilation systems provide air-filtering options. This feature can prevent the stove from burning dust or hair that collects in broadband. This also cleans the air as it warms and leaves the room smelling fresh.
When you choose a space heater, safety is most important. Many models have safety mechanisms that prevent burns and fires. A tip-over switch detects when the space heater has been overthrown and automatically turns it off. Similar switches can cool the coils when touched or cut power to the entire plant when it gets covered with something.
The Best Portable Heaters
A good portable heater does not have all the opportunities that exist above, but it may be wise to make a list of the most coveted opportunities before making a decision. There are plenty of quality space heaters on the market, so take your time to narrow the field before you go shopping.
Homeowners who are looking for a large water heater should look at a model as DeLonghi Safe Heat. At about $ 200, it also provides heat a larger area without space-consuming. The offsets have safety equipment and splash resistance for use in the bathroom. The heater is capable of heating your room, while reducing your electricity bills.
Oven like Newair AH-510E Electric Fireplace Heater off the same price and give warmth, but adds the charm of a fireplace. This model has a timer and coils glow like little flames. Although perhaps not as portable as some other electrical options, a fireplace heater to be moved more easily than ventilated stoves.
For a smaller, cheaper solution, try World Marketing Electric Convection Heater. It heats quickly and provides variable control of temperature and fan. It also has a tripping switch. This little heater even come under $ 30.
Those who wish to add an attractive but expensive heater to their homes should consider Honeywell HZ519 Digital Low Profile Silent Comfort Heater. It is a long, slim device that sits low to the ground and silently warms the room. It has a digital thermostat, a timer that allows for automatic switching off, and more safety. At $ 1,000, this unit has virtually everything you could wish for in a radiator.
Although these ovens have different prices and options, they can all participate comfortably warm any room during the winter. The best part is that they all are completely portable, so they can be moved from one room to another. Just remember never to leave them on and unattended.

BAGLESS VACUUM CLEANER

BAGLESS VACUUM CLEANER

One of the most common problems in maintaining a vacuum cleaner is to ensure that its end is in the best conditions. Often this leads to consumers to replace their vacuum bags more often than not. This is a good reason to make the transition to a bagless vacuum cleaner. It requires less maintenance and is apparently more effective than one requiring a bag. Here is a baglesss vacuum cleaner review a few models from differe

Bissell Power Force Bagless Upright

Although canister vacuum cleaners are more popular these days, the upright models still may find that entering the market and in consumers' homes. After all, still upright models are very useful, and now that they come in a bagless version, they have just become even more important to have around the house. The Bissell Powerforce is inexpensive and is special because there are features that are only really ever found on more expensive models. With a large dirt container instead of a bag, this gives the bagless vacuum cleaner to collect more dirt and hair out of carpets. The container is also very easy to remove in order to dispose of the dirt, much like throwing rubbish from a rubbish bin in a dump truck. Cleaning is a minor chord against bags, because you can give the container a quick wash and have it on the road almost in an instant.
nt manufacturers


Phantom Fury

It seems that the bagless vacuum cleaners are becoming more popular in those days. Take Phantom Fury, for example. It is an excellent vacuum cleaner that is extremely easy and, like most other upright bagless vacuum cleaners, you'll find the dirt vessel right on top of the cleaning head. This makes it even easier to move around the house. With the clear cans, you could see all the dirt collected from the carpet and various floor surfaces. And when the bottle is filled, it is easily emptied, again, like emptying a dustbin. The Fury also comes with a long lasting HEPA filter and is recommended for those allergic to dust particles.

Why do the Switch ?

This bagless vacuum cleaner review insists that you make the change. While it is true that consumers have become accustomed to the original design of a vacuum with a bag, the error is that they will end up spending more because they need to change these bags like they are full. A bagless vacuum vessel only be emptied out and then can be used again. Furthermore, a vacuum that uses bags most likely be clogged with all sorts of dirt and hair it picks up. This will require more maintenance by the consumer, while a bagless vacuum cleaner would save the consumer lots of time. It seems that the bagless variety (with their strong suction mode) itself could leave your floors and carpets even cleaner than their bagged counterparts.

Saturday 19 November 2011

3D CREATION

3D ON ROAD




















ultrasonic motor's steps in engineering

FUTURE ENGINEERING

In office equipment such as printers and floppy disk drives, market research indicates that tiny motors smaller than 1 cm3 would be in large demand over the next ten years. However, using the conventional electromagnetic motor structure, it is rather difficult to produce a motor with sufficient energy efficiency. Piezoelectric ultrasonic motors, whose efficiency is insensitive to size, are superior in the mm-size motor area. There is today a large variety designs exploiting motion obtainable from the inverse piezoelectric effect. Ultrasonic piezomotors have a very special place among such devices .These motors achieve high speed and drive forces, while still permitting the moving part to be positioned with very high accuracy. Such characteristics make these motors of great interest for many
companies who make precision devices for which these drives are, in many cases, irreplaceable.

MERITS AND DEMERITS OF ULTRASONIC MOTOR

MERITS AND DEMERITS


Merits
  • Low speed and high torque - direct drive
  • Quick response, wide velocity range, hard brake and no backlash: excellent controllability; fine position resolution.
  • High power/weight ratio and high efficiency.
  • Quiet drive.
  • Compact size and light weight.
  • Simple structure and easy production process.
  • Negligible effect from external magnetic or radioactive fields, and also no generation of these fields.

Demerits

  • Necessity for a high frequency power supply.
  • Less durability due to frictional drive.


 

WORKING PRINCIPLE OF ULTRASONIC MOTOR.

PRINCIPLE OF WORKING

The working principle of Ultrasonic motor is shown in figure. High order curling vibration is generated on the surface of the elastic vibrator (stator) and travelling eaves are made by excitation of the piezoceramic vibrator. And the certain pressure causes the slider to propagate on stator by the friction between them. Driving force of Ultrasonic motor is obtained by travelling-wave type elastic curling wave. This type of motor is named as travelling wave type Ultrasonic motor. For generating elastic curling wave on the elastic annular plate, adhere the piezoceramic vibrator beneath the annular plate and exploit the expanding and contracting wave. That is piezoceramic vibrator beneath the elastic annular plate is polarized and when AC voltage is applied to the vibrator, sectional expanding and contracting move occurs and elastic curling waves are generated on the elastic annular plate

ROBOTIC HAND DRIVEN BY ULTRASONIC MOTOR

ROBOTIC HAND DRIVEN BY ULTRASONIC MOTOR



 Five fingered robot hand driven by 20 ultrasonic motors. Each finger has five degrees of freedom. The size is about the same as that of human hands. As ultrasonic motor has characteristics such as rapid response, large torque and silence, it is adequate for robot hand. Speed of fingers is faster than that of humans. So this hand is adequate for use in master-slave system for remote control in the medical and extreme environment. Now researches aiming to construct a master-slave system to show the applicability of our hand to dexterous manipulation

Friday 18 November 2011

PROGRAMMABLE LOGIC CONTROLER

PLC



Controlled engineering has evolved over a long period of time. in the Past human were the controlling device for a system. More recently electricity has been used for control and the early control is done by the help of electrical relays. The relays allow the supply can switched ON and OFF electrically without out a mechanical switch. Nowadays relays are common to make simple logical control decisions. The development of low cost computes discovers the most recent control system, Programmable Logic Controller (PLC).The advent of PLC began in the 1970’s.Today PLC is most common for controlling processes.


The PLC is used as a standard in the field of automation for control. It replaces earlier relay controls and taken over many additional functions.


The PLC is designed by a computer to operate in industrial environment and arranged with special input, output and a control programming language for use in machine.


The PLC is designed to controlling a system, but it is finding many and more complex applications. The structure of PLC and computer architecture are constructing based on the same principles, so the relay performing not only the relay switching but also counting ,processing ,calculating and comparing of analog signals.


PLC is a microprocessor based computer, which is user friendly and performs control functions of different types and of different levels of complexy. A PC can be used as PLC with input sensing devices such as push button , switches ,.etc; input according some conditions. A program is needed to process Input and the PLC turn ON and OFF load devices by means of Ladder Diagram. It essential to draw a Ladder Diagram of controlling of devices with laptop or PC. The drawing is converted into computer language and runs as user rogram

BLOCK DIAGRAM OF PLC

BLOCK DIAGRAM OF PLC SYSTEM



 
 
 
 
 
 
 
 
 
 
 
 
Simplified Block Diagram of a PLC system. It contain main parts:

  • CPU(Central Processing Unit)
  • Input sensing devices
  • Input interfaces
  • Output interfaces
  • Programmer/Monitor

PLC

LADDER DIAGRAM

Ladder Logic language is a PLC programming language, means by which the user communicate information to PLC. Appearance of the Ladder Logic Language designed as a wired relay system, so it termed as a Graphical Programming Language. It is a symbolic set instruction used to create the controller program (representation of contacts and coils are the basic symbols of the ladder diagram). The corrective arrangement of these symbols made possible to create a desired control logic that is to be entered into the memory of the PLC. Ladder program prepared for a specific function is composed of symbols of contacts and coils and it is also called contact symbology .The Ladder Program controls the output based on input conditions. The control is done according to what is is referred by the ladder rung and the rung is consist of set of input conditions, represented by the contact symbols, at the end of rung output is represented by the coil symbols .Each contacts and coils are represents with an address number and which identifies what is being evaluated and controlled.

SPEED CONTROL OF MOTOR

SPEED CONTROL OF SERIES MOTOR


The automatic speed control of a series motor to a constant is done by automatic adjustment of triggering angle at various loads using feedback signal which is proportional to the actual speed of the motor. The feedback signal can be obtained using tachogenerator or from the back emf produced across the armature.
It can be run both DC and AC input, speed control of a universal motor can also possible using this circuit.

Capacitor ‘C’ charges through Resistance ‘R1' and variable resistance ‘Rv’ during +ve half cycle. When capacitor voltage become ‘Vc’ (equal to Break over voltage of diac VBO + back emf ‘Eb’ of the armature),SCR gets triggered. Now the motor current flows through the series field, conducting SCR, and armature of the motor. The speed of the motor can be controlled by varying the charging time of the capacitor and which can be done by varying variable resistance ‘Rv’. When the SCR is not conducting the armature current is due to residual magnetism and is approximately proportional to the speed. Diode D is used to avoid –ve excursions of capacitor voltage.
If the load increased, it will tends to slow down the motor. Reduced speed results reduction and lower value of back emf ‘Eb’.The increased difference between ‘Eb’ and ‘Vc’ will trigger the SCR earlier than before in next positive half cycle. ‘VBO’is constant and back emf Eb’ decreased, the capacitor takes less time to reachVBO+Eb’,there for SCR triggers earlier. As a result the voltage across the armature increased and motor retain the preset value speed. If the speed rises because of some decreasing of load,the triggering angle will automatically advance and bring down the speed to preset value.
In series motor drive, the current flows through the armature and field when the SCR is triggered at an angle ‘alpha’.The current continues beyond ‘omega*t=pai’until the stored energy of the armature is dissipated. The armature voltage is –ve for some time beyond ‘omega*t=pai’.

Thursday 17 November 2011

Ultrasonic Motor's Reliability


Reliability of Ultrasonic Motor.
In the development of ultrasonic motors, the following themes should be systematically studied:
  • Measuring methods for high-field electromechanical couplings.
  • Materials development (low loss and high vibration velocity).
  • Piezo-actuator designs. (Heat generation mechanism ,Degradation mechanisms,New multilayer actuator designs)
  • USM designs (Displacement magnification mechanisms (horn, hinge-lever),USM types (standing-wave type, propagating-wave type),Frictional contact part.)
  • Drive/control (High frequency/high power supply,Resonance/anti-resonance usage.

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