ADVANTAGES OF BLUETOOTH TECHNOLOGY

1. No line of site restrictions as with IrDA.
2. Low power consumption makes integrated in battery powered devices very practical.
3. GHz radio frequency ensures worldwide operability.
4. Tremendous momentum not only within the computer industry but other industries like cellular telephones and transportation.
 

What is power factor? Whether it should be high or low? Why?

ANS:
Power factor should be high in order to get smooth operation of the system. Low power factor means losses will be more. it is the ratio of true power to apparent power. It has to be ideally 1. if it is too low then cable over heating & equipment overloading will occur. if it is greater than 1 then load will act as capacitor and starts feeding the source and will cause tripping. (If pf is poor ex: 0.17 to meet actual power load has to draw more current(V constant),result in more losses if pf is good ex: 0.95 to meet actual power load has to draw less current(V constant),result in less losses).
 

Types of capacitors

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Inductor ...

image below:

3-phase-loads

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How self-driving cars drive itself precisely??

ANS:
For a car to drive itself, few systems must be tied together using software, and supplemented with a set of sensors.
Lane-keeping systems - To follow road markings and sound a warning and correct the steering if a vehicle starts to drift out of its lane
Adaptive cruise control – To maintains a constant distance from the vehicle in front, rather than a constant speed
Auto-parking systems - which can reverse a car into a parking space
Emergency braking - which slams on the brakes if an obstacle, another vehicle or a pedestrian is detected in front of the car
Satellite-navigation systems.
 

What is circuit breaker?

## circuit breaker: 

A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit. Its basic function is to detect a fault condition and interrupt current flow. Unlike a fuse, which operates once and then must be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. Circuit breakers are made in varying sizes, from small devices that protect an individual household appliance up to large switchgear designed to protect high-voltage circuits feeding an entire city.

Lightning and Over-Voltage Protection

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whats the one main difference between UPS & inverter ? And electrical engineering & electronics engineering ?

ANS:
uninterrupt power supply is mainly use for short time . means according to ups VA it gives backup. ups is also two types : on line and offline . online ups having high volt and amp for long time backup with with high dc voltage.but ups start with 12v dc with 7 amp. but inverter is startwith 12v,24,dc to 36v dc and 120amp to 180amp battery with long time backup.

All about electric Symbols

below symbols:

What is the difference between transformer and auto-transformer?

ANS:
A typical transformer has two windings.. the primary and the secondary of which the two windings are not electrically connected..
An auto transformer, there is only one winding that acts as the primary and a portion of it as the secondary winding. The primary and secondary windings are electrically connected.This is the main  difference between transformer and auto-transformer

Difference Between BJT and MOSFET

 Difference Between BJT and MOSFET

1. BJT is a Bipolar Junction Transistor, while MOSFET is a Metal Oxide Semiconductor Field-Effect Transistor.
2. A BJT has an emitter, collector and base, while a MOSFET has a gate, source and drain.
3. BJTs are preferred for low current applications, while MOSFETs are for high power functions.
4. In digital and analog circuits, MOSFETs are considered to be more commonly used than BJTs these days.
5. The operation of MOSFET depends on the voltage at the oxide-insulated gate electrode, while the operation of BJT is dependent on the current at the base.
 

What is the difference between electronic regulator and ordinary electrical rheostat regulator for fans?

ANS:
The difference between the electronic and ordinary electrical regulator is that in electronic regulator power losses are less because as we decrease the speed the electronic regulator gives the power needed for that particular speed but in case of ordinary rheostat type regulator, the power wastage is same for every speed and no power is saved.In electronic regulator, triac is employed for speed control by varying the firing angle speed and it is controlled but in rheostatic ,control resistance is decreased by steps to achieve speed control.

WHAT IS ELECTRICITY?

ANS:

Electricity is a form of energy. Electricity is the flow of electrons. All matter is made up of atoms, and an atom has a center, called a nucleus. The nucleus contains positively charged particles called protons and uncharged particles called neutrons. The nucleus of an atom is surrounded by negatively charged particles called electrons. The negative charge of an electron is equal to the positive charge of a proton, and the number of electrons in an atom is usually equal to the number of protons. When the balancing force between protons and electrons is upset by an outside force, an atom may gain or lose an electron. When electrons are "lost" from an atom, the free movement of these electrons constitutes an electric current.

switchgear

switchgear :

In an electric power system, switchgear is the combination of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream. This type of equipment is important because it is directly linked to the reliability of the electricity supply.

What is Three-phase electric power?

ANS:

Three-phase electric power is a common method of alternating-current electric power generation, transmission, and distribution.It is a type of polyphase system and is the most common method used by electrical grids worldwide to transfer power. It is also used to power large motors and other heavy loads. A three-phase system is usually more economical than an equivalent single-phase or two-phase system at the same voltage because it uses less conductor material to transmit electrical power.The three-phase system was independently invented by Galileo Ferraris, Mikhail Dolivo-Dobrovolsky and Nikola Tesla in the late 1880s.
 

Why should be the frequency 50 Hz 60Hz only why not others like 45, 95 56 or anything , why should we maintain the frequency constant if so why it is only 50 Hz 60Hz?

►Ans:

We can have the frequency at any frequency you like, but than you must also make your own motors,high voltage transformers or any other equipment you want to use.We maintain the frequency at 50hz or 60hz because the world maintains a standard at 50 /60hz and the equipments are are made to operate at these frequency.

Construction of a Simple Mobile Phone Jammer

Construction of a Simple Mobile Phone Jammer

 

What is the difference between electronic regulator and ordinary electrical rheostat regulator for fans?

ANS:
The difference between the electronic and ordinary electrical regulator is that in electronic regulator power losses are less because as we decrease the speed the electronic regulator gives the power needed for that particular speed but in case of ordinary rheostat type regulator, the power wastage is same for every speed and no power is saved.In electronic regulator, triac is employed for speed control by varying the firing angle speed and it is controlled but in rheostatic ,control resistance is decreased by steps to achieve speed control.

Diode definition

Ans:

An electrical device with two active terminals, an anode and a cathode, through which current passes more easily in one direction (from anode to cathode) than in the reverse direction. Diodes have many uses, including conversion of AC power to DC power, and the decoding of audio-frequency signals from radio signals.
or, 
 The heated cathode generates a cloud of electrons that are attracted by the anode, causing a current to flow from the cathode to the anode. Because the anode cannot generate electrons of its own, the current cannot flow in the opposite direction.

How electric rice cooker works

Ans:
The bowl in the rice cooker is usually removable, and beneath it lies a spring and thermostat. These form the main components of the rice cooker. The spring in the bottom is simply to ensure contact of the thermostat to the base of the cooking bowl. During cooking the mixture is continuously heated. The temperature cannot go above the boiling point of water—100°C (212°F)—as any energy put into the system at that point will only cause the water to boil. At the end of cooking all of the water will have been evaporated or absorbed by the rice. Once the heating continues past this point, the temperature exceeds the boiling point. The thermostat then trips, and switches the rice cooker to "warm" mode, keeping the rice no cooler than approximately 65°C (150°F). Simple rice cookers, like the one below, may simply turn off at this point.
 

phota diode definition

Ans:
The structure of an optical receiver is simple consisting of just a photodiode to produce the electrical current and an amplifier But do not be fooled it is far more complex to design a really high performance optical receiver The structure of an optical receiver is simple: consisting of just a photodiode to produce the electrical current and an amplifier.
 

Hand Generator

What is meant by knee point voltage?

ANS:
Knee point voltage is calculated for electrical Current transformers and is very important factor to choose a CT. It is the voltage at which a CT gets saturated.(CT-current transformer).

Why transformer ratings are in kva?

ANS:
Since the power factor of transformer is dependent on load we only define VA rating and does not include power factor .In case of motors, power factor depend on construction and hence rating of motors is in KWatts and include power factor.

Why in a three pin plug the earth pin is thicker and longer than the other pins?

Ans:

 It depends upon R=rho l/a where area(a) is inversely proportional to resistance (R), so if (a) increases, R decreases & if R is less the leakage current will take low resistance path so the earth pin should be thicker. It is longer because the The First to make the connection and Last to disconnnect should be earth Pin. This assures Safety for the person who uses the electrical instrument.

 

Construction of three pin plug

construction of electrci car

Touch Switch Project

■ Touch Switch Project :

THEAFS ARE ATTRACTED TO EXPENSIVE THINGS WHEN THEY COME IN OUR HOUSES. WE CAN PROTECT OUR PRODUCT OR THING BY MAKING THEM TOUCH PROOF OR WE CAN STOP ANY UNIDENTIFIED PERSONS ENTRY IN OUR HOUSE BY MAKING DOOR AND WINDOW TOUCH PROOF.THIS CIRCUIT ALERT US WHEN ANY THEAF COME TO STOLE PRODUCTS FROM OUR HOUSE OR TOUCH ANY METALLIC THING AT DOOR / WINDOW OR IN SIDE . WE CAN USE THIS CERCUIT TO PROTECT OUR CAR OR BIKE BY MAKING THEM TOUCH PROOF.

AS WE HAVE DISCRIBE ABOVE THIS PRODUCT GIVE ALARM WHEN ANY HUMAN BODY TOUCH ANY OF THE METTALIC THING WHICH ARE PROTECTED BY THIS CIRCUIT. THIS PROJECT IS WORKING ON TWO TRANSISTORS
WHICH MAKE COMPLIMENTORY PAIR DIRECT COUPLED AMPLIFIER. THIS CIRCUIT BASICALLY A AUDIO OSILATOR FOR OSILATION WE USE COLLECTOR OF TRANSISTOR BC558 WHICH IS CONNECTED TO THE BASE OF TRANSISTOR BC 548 VIA RESISTANCE 18 K .01 or .02 MFD CAPACITOR . TRANSISTOR BC-548 IS WORKING AS A PREAMPLIFIER.
WHEN ANY HUMAN BODY TOUCH THE TOUCH SENSOR WHICH IS CONNECTED TO BASE OF TRANSISTOR BC-548. THIS TRANSISTOR CONDUCT WITH HUMAN SKIN CONDUCTANCE . WHEN TRANSISTOR BC-548 START CONDUCTING IT’S FORCED TO TRANSISTOR BC558 TO START CONDUCTING . SO WE GET ALARM SOUND FROM SPEAKER. WHEN WE TAKE BACK OUR HAND THEN DOES NOT CONNECTED TO BASE OF TRANSISTOR BC-548 . SO IT’S DOES NOT CONDUCT WE DO NOT GET THE ALARM SOUND.
 

FDM Means and block diagram

ANS:
frequency-division multiplexing (FDM) is a technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency sub-bands, each of which is used to carry a separate signal. This allows a single transmission medium such as the atmosphere of Earth, a cable or optical fiber to be shared by many signals.
The most natural example for frequency-division multiplexing is the old traditional radio and television broadcasting, using the natural atmosphere of Earth. An other example of a system using FDM is cable television, in which many television channels are carried simultaneously on a single cable. FDM is also used by telephone systems to transmit multiple telephone calls through high capacity trunklines, communications satellites to transmit multiple channels of data on uplink and downlink radio beams, and broadband DSL modems to transmit large amounts of computer data through twisted pair telephone lines, among many other uses.
below diagram:
 

How does a DC Generator work?

 ANS:
D.C. generator works upon the principle of Electromagnetic induction that includes both Faraday's laws and Lenz's law.
To understand the working of a D.C. Generator,it is logical to get first get a brief idea of its construction part.
The D.C. generator(or any D.C. machine) has the following parts:

Stationary members(Stator)
Stator frame
Stator core
Field windings
Brushes

Rotary members(Rotor):
Armature core
Armature windings
Bearings

Now,the working of the generator can be explained as:
The field windings are provided with a current so as to develop a magnetic field around the armature(rotor) of the generator.This phenomenon is also known as field Excitation.
When the armature is made to rotate with the help of any prime mover in the magnetic field as generated by the stator side,an emf is induced in the armature.The magnitude of this generated emf is given by Faraday's law while the direction is given by Lenz's law.
When the armature windings are connected to any load,an electric current begins to flow.
In this way,a DC generator works.
 

AC Generators basic

AC generators are electromechanical machines that use the turning of a rotor in a magnetic field to generate alternating current electricity. You use the output of an AC generator when you turn on a light or start your car. The power company's AC generators that power your house are at the large end of the size range. The alternator in your vehicle is at the small end.

DC Generators basic

Direct current (DC) is the flow of an electrical charge in one direction. Examples of this type of current include batteries and solar cells. Thomas Edison, who subsequently held many patents involving direct current, first demonstrated it. At that time, all public electricity was direct, and when Westinghouse and Tesla proposed switching to alternating current (AC), Edison bitterly opposed the idea so as not to lose his patent royalties. Nowadays, AC is used in all homes, but DC still has its particular uses, primarily as generators in large industrial settings and in charging batteries.

solar panel

A solar panel  is a packaged, connected assembly of photovoltaic cells. The solar panel can be used as a component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications. Each panel is rated by its DC output power under standard test conditions, and typically ranges from 100 to 320 watts. The efficiency of a panel determines the area of a panel given the same rated output - an 8% efficient 230 watt panel will have twice the area of a 16% efficient 230 watt panel. Because a single solar panel can produce only a limited amount of power, most installations contain multiple panels. A photovoltaic system typically includes an array of solar panels, an inverter, and sometimes a battery and or solar tracker and interconnection wiring.
 

speaker for your laptop

Diagram:

basic logic gates tutorial

Logic gates:

 Digital systems are said to be constructed by using logic gates. These gates are the AND, OR, NOT, NAND, NOR, EXOR and EXNOR gates. The basic operations are described below with the aid of truth tables.

 AND gate

 The AND gate is an electronic circuit that gives a high output (1) only if all its inputs are high.  A dot (.) is used to show the AND operation i.e. A.B.  Bear in mind that this dot is sometimes omitted i.e. AB

 OR gate

 The OR gate is an electronic circuit that gives a high output (1) if one or more of its inputs are high.  A plus (+) is used to show the OR operation. 

NOT gate

The NOT gate is an electronic circuit that produces an inverted version of the input at its output.  It is also known as an inverter.  If the input variable is A, the inverted output is known as NOT A.  This is also shown as A', or A with a bar over the top, as shown at the outputs. The diagrams below show two ways that the NAND logic gate can be configured to produce a NOT gate. It can also be done using NOR logic gates in the same way.

NAND gate

This is a NOT-AND gate which is equal to an AND gate followed by a NOT gate.  The outputs of all NAND gates are high if any of the inputs are low. The symbol is an AND gate with a small circle on the output. The small circle represents inversion.

 

NOR gate

This is a NOT-OR gate which is equal to an OR gate followed by a NOT gate.  The outputs of all NOR gates are low if any of the inputs are high.

The symbol is an OR gate with a small circle on the output. The small circle represents inversion.

 

 

EXOR gate

The 'Exclusive-OR' gate is a circuit which will give a high output if either, but not both, of its two inputs are high.  An encircled plus sign () is used to show the EOR operation.

EXNOR gate

The 'Exclusive-NOR' gate circuit does the opposite to the EOR gate. It will give a low output if either, but not both, of its two inputs are high. The symbol is an EXOR gate with a small circle on the output. The small circle represents inversion.

The NAND and NOR gates are called universal functions since with either one the AND and OR functions and NOT can be generated.

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