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Electronics Engineering

Electronics Engineering is a branch of engineering that deals with practical applications of electronic components, devices, systems, or equipment. Electronics are devices that operate on low voltage sources, as in electron tubes, transistors, integrated circuits, and printed circuit boards and use electricity as part of its driving force.

24,372 Questions

What is the full form of IGBT?

The full form of igbt is insulated gate bipolar transistor.

it is constructed from the combining of both BJT and PMOSFET.

it has high input impedance and low on - state power loss .

it is free from second break down problem present in bjt...

it is also known as (MOSIGT), (COMFET)...

it is constructed virtualy in the same manner as a power

MOSFET.an IGBT has also thousand of basic structure cells

connected appropritely on a single chip of silicon.

it has a four substrate p,p+,n+,n-. respectively...

p+ substrate is called injection layer because it injects

holes into n- layer .n- layer is called drift region .

thickness of the n- layer determines the voltage blocking

capability of IGBT.

the p layer is called body of the IGBT.

WHERE IT IS USED : it is widely used in medium power

application such as DC and AC motors drives.

UPS SYSTEMS , RELAYS AND CONTACTORS.

In thyristor the gate is triggered the gate is losses its

control. ie if we remove the gate pulse after the thyristor

starts conducting it will not stop.

but in IGBT we can control the Gate. by applying reverse

voltage applied across it .

The Thyristors can not be switched beyond 1kHz where as

IGBTs can be switched upto 25kHz and even to 100KHz with

few soft switching techniques.

The thyristor can carry very high currents order of 3000A

but IGBT carries less current max of 1000A.

Thyristor commutation ,that is switching off is very

difficult. But there are applications of Thyristor with

natural commutation.

The IGBT can be switched on and off like a MOSFET. ie it is

voltage controlled device.

How would you measure a relays contacts resistance?

The voltage drop across a relay coil will be the same as the coil supply voltage. If you are trying to see if the coil is good or not, remove one of the voltage supply leads and check for continuity by using an ohm meter across the coil leads. A reading will tell you that the coil is intact and not open.

How much current will a circuit need if it has twenty four ohms of resistance and a twelve volt power supply?

If the resistance of the wire is 20 ohms and the voltage between the two ends of the wire is 20 volts,

then the current through the wire is

I = E/R = (40/20) = 2 amperes.

Voltage frequency inverter dc or ac output?

An inverter changes a d.c. input to an a.c. output.

Inverter is a device to change low

volt DC to high volt AC

12 Dc to 220 Ac volt

So many type of inverter of watts

500 watt 1000 watt 5000 watt

What is the total resistance of three resistors in parallel with values of 2 ohms 8 ohms and 14 ohms?

Current, by Ohm's Law, is voltage divided by resistance, so, 18 volts divided by 2 ohms is 9 amperes.

Where is microwave communication used?

They were first used to communicate. A worker on an active antennae noticed that while it was sending microwaves out, a candy bar melted in his shirt pocket. He then designed a box that would capture and reflect these microwaves to heat up food and liquids. We call it the microwave oven.

What is the voltage drop through a resistor of 6 ohms(2amps)?

Assuming the these resistors are connected in series, the voltage drop across each resists can be calculated simply using V = IR. In a series circuit, the same current must flow through each resistor. So, 2*i + 2*i + 2*i = 6 volts. or i * 6 = 6, or i = 1. So, the voltage drop across all resistors i*r is 2 volts.

The output voltage from a PC power supply are?

Generally, there will be a 12+ volt rail, a 5+ volt rail and often a 3+ volt rail.

Why should an ohmmeter never be used on an energized circuit?

Because an ohmmeter works by putting a potential difference (voltage) across a load and measuring the resulting current (the current will be inversely proportionate to the resistance). In a live circuit there is already current flowing through the load so (at best) the reading will be inaccurate, at worst the meter will be damaged.

What is status of a circuit that is complete and unbroken with flowing electric current?

A circuit that is complete and unbroken with flowing electric current normally has steady supply of voltage with no broken links. Electrical energy flows to light up a bulb or do similar work. Its status is complete, nothing else is needed.

Are microwaves dangerous to humans?

As long as it hasn't been damaged in any way and is taken care of, a microwave can be used for many years - my own parents are using both a standard microwave and a combination microwave/conventional oven that they've owned since 1982.

The main health hazards with microwaves are to people with pacemakers and similar type medical implants - not all microwaves are taken care of the same.

What is AV in electronics?

AV stands for Audio Visual, i.e. engineering systems in sound or video production, encompassing TVs, monitors, receivers, amplifiers, soundbars and so on. All of those components requires electronic design to create in the first place, and also to some extent some knowledge of electronics can be a help in building AV systems that are constructed from many discrete components.

What is the difference between local oscillator and oscillator?

Oscillator is a generic word for any circuit that produces an alternative signal.

The shape of the signal, its stability and its output impedance are not considered in this case.

"Local oscillator" is one specific type of oscillator used in radio receiver for the purpose of frequency conversion. the input Radio Frequency( RF ) signal is "mixed" with the local oscillator signal and the subtraction of two frequencies is obtained at the output.

"Mixing" in this context means: "multiplication"\

In some other context in electronics (specially audio) mixing means "adding"

the mathematical operation for local oscillator is F out=Fin - F loc.osc.

The output of the mixing operation can also be Fin+F loc.Osc. But this higher frequency is usually filtered out.

The local oscillator needs to be a pure sine wave with a very good frequency stability and usually very stable output voltage.

Recently very good "synthesizers" are introduced in the market that permit generation "programmable local oscillation"

What does an oscillator do?

Oscillators are used in a lot of applications. The fact that they oscillate, meaning switch between a zero and positive orbetween a negative-positive value in a repetitive way, makes them useful as a time base.

As time base, they can be used to activate processes that are time-dependent, eg. a computer: has an internal clock (several, to be more corect) that is driven by a kind af an oscillator.

Most of these oscillators to drive time-based electronics are digital, meaning the oscillation is a square wave between 0volts and some positive value (eg. 3.3V or 5V)

Another common use of oscillators is for data communication: a waveform of a certain frequency is generated by an oscillator, and information is superponed on this electromagnetic wave.

Other appliances that use waves generated by oscillators are like microwave ovens, radar, sybthesizer, clock radio, modem (both digital and analog types), sirens, Christmas lights, ...

You can be sure, if it has anything complicated electronic in it, it almost certainly has an oscillator build in.

see also http://en.wikipedia.org/wiki/Oscillation

Why consider only 3dB for bandwidth calculation?

3dB of gain rolloff is a linear reduction of gain by a factor of 2. That makes it a good reference point.

Can you replace 2200 uf 24 volt capacitor with a 2200 uf 16 volt capacitor?

NO dont do it if you devalue a capacitors voltage parameter what will it do when it is face to face with 20V ? The voltage will destroy the thing. Remember it is OK for you to use a higher voltage parameter for a capacitor but never lower

Can you use a dc-ac power inverter to run a battery charger to charge another battery?

No. There are losses involved with each stage of the conversion, from DC to AC, and from AC back to DC. The battery running this would gradually discharge. Any other result would constitute a perpetual motion machine which, in this imperfect world, is impossible.

Is Clarence L Elder alive in 2016?

I have not seen any reports on Ancestry.com or other genealogy sites that give a death date for him, and it is certainly possible he is still alive; having been born in November 1935, he would be 81 years old in 2016.

What would the current be if an extra battery was added to a circuit?

If you add more batteries in series, the voltage would increase. This would drastically change the circuit. Normally this should also produce more current.

The effect of adding more batteries in parallel is insignificant for many circuits. Adding more batteries in parallel is like lowering a battery's internal resistance - which, for many circuits, can be neglected.

Example: The battery's internal resistance can be neglected; the battery gives a voltage of 12 volt, you connect it to a resistance of 2 ohm. According to Ohm's law, that will give you a current of 6 ampere. Note that the battery capacity does not enter the calculation! Adding a second battery (of the same kind) will produce the same voltage, thus, the same current.

If you add more batteries in series, the voltage would increase. This would drastically change the circuit. Normally this should also produce more current.

The effect of adding more batteries in parallel is insignificant for many circuits. Adding more batteries in parallel is like lowering a battery's internal resistance - which, for many circuits, can be neglected.

Example: The battery's internal resistance can be neglected; the battery gives a voltage of 12 volt, you connect it to a resistance of 2 ohm. According to Ohm's law, that will give you a current of 6 ampere. Note that the battery capacity does not enter the calculation! Adding a second battery (of the same kind) will produce the same voltage, thus, the same current.

If you add more batteries in series, the voltage would increase. This would drastically change the circuit. Normally this should also produce more current.

The effect of adding more batteries in parallel is insignificant for many circuits. Adding more batteries in parallel is like lowering a battery's internal resistance - which, for many circuits, can be neglected.

Example: The battery's internal resistance can be neglected; the battery gives a voltage of 12 volt, you connect it to a resistance of 2 ohm. According to Ohm's law, that will give you a current of 6 ampere. Note that the battery capacity does not enter the calculation! Adding a second battery (of the same kind) will produce the same voltage, thus, the same current.

If you add more batteries in series, the voltage would increase. This would drastically change the circuit. Normally this should also produce more current.

The effect of adding more batteries in parallel is insignificant for many circuits. Adding more batteries in parallel is like lowering a battery's internal resistance - which, for many circuits, can be neglected.

Example: The battery's internal resistance can be neglected; the battery gives a voltage of 12 volt, you connect it to a resistance of 2 ohm. According to Ohm's law, that will give you a current of 6 ampere. Note that the battery capacity does not enter the calculation! Adding a second battery (of the same kind) will produce the same voltage, thus, the same current.

What is the difference between the nand gate ic's 74ls00 and 74ls132?

The 74LS00 is a logic NAND gate with normal logic level inputs. This means that the inputs has a low range below 0.8V, unrecognised range and a high range above 2V. At any time a input signal crosses those levels, a change in state can be expected. Applicable to the LS family, they have a floating input that means it is uncertain the state of logic level if no input is connected. Therefore never assume that since the input is not connected that the circuit will assume a zero, it can be either zero or one.

The 74LS132 is also a NAND gate logic function. But different to the Logic level input it uses what we call a Schmitt trigger input to improve noise immunity in a circuit. In simple terms; it's really nothing more than a comparator input. But the Schmitt trigger also have a hysteresis, which help to eliminate the affect what noise have on the circuit.

On a more technical note

Each circuit contains a 2-input Schmitt trigger followed by a Darlington level

shifter and a phase splitter driving a TTL totem pole output. The totem pole is basically a push-pull output stage constructed with two p-n-p transistors and a diode on the output.

The comparator function would mean that there is a particular threshold level on the input and if the input voltage pass the particular level, the output or intermediate state of the function will change state. In the case of multiple logic inputs the change of input state does not necessarily mean a change in output state and therefore I will refer to an intermediate area inside the function related to the input state.

The hysteresis create a high and low trigger points. This cause the input to at least pass the high trigger point of about 1.6V before the intermediate state will change or drop below the 0.9V before the intermediate state change back again. Therefore the practical unit will not have one particular level to change state but these two fixed trigger points must be used.

It sounds like it complicates matters but it really helps to handle input noise signals which makes the Schmitt trigger a handy device. Making it a good device for signal conditioning of logic signals in some applications.

Also take note that the high and low hysteresis trigger points may vary with supply voltage. In fact I do not recommend it as standard practice to use a Schmitt trigger to evaluate analogue levels, some engineers may differ but I would rather refer to a real comparator circuit design where you have more control over precision, trigger points and reference levels. But may be considered for logic inputs from sensors or conditioning of logic signals

Some circuits may also employ Schmitt trigger devices for oscillators and contact debouncing

Why logic gates are called logic gates?

Logic Gates are electronic building blocks of a digital system.

Their physical manifestation may take any form, but essentially a logic gate consists of a collection of binary digits and a set of rules where such digits are combined to give a resulting set of binary digits.

The rules that are implemented by logic gate are of the fundamental Boolean Algebraic Operations.

Logic gates may be coupled together so that digital input to a system produces a predetermined digital output. It is a logical set of rules. The concept of digital information flowing into a system through an electronic pathway coveys a perception that gave someone the idea of a gate when this was named long ago.

How do you construct a 3 ip nand gate using only 2 ip nand gates?

To produce a 3-input OR gate when only 2-input OR gates are available: Use 3 OR gates Inputs to Gate A are input 1 and input 2 Input to Gate B is input 3 (if 2 inputs are necessary, include input 3 and FALSE) Inputs to Gate C are outputs from Gate 1 and Gate 2 === If input 1 OR 2 is TRUE, output of Gate A will be TRUE. If input 3 is TRUE, output of Gate B will be TRUE. If output of Gate A OR Gate B is TRUE, output from Gate C will be TRUE. That is if one ore more of Inputs 1, 2 or 3 is TRUE, the result will be TRUE. Otherwise, output of Gate C will be FALSE.

What is standoff ratio in UJT?

the amount of potential to forward bias it

A clamp on ammeter measures?

Measures current by magnetic field induced into the clamp. You need to clamp a single conductor. For example you couldn't just clamp a lamp cord since it has two conductors and the current is going in opposite directions and the fields cancel each other out.

What are the advantages of half and full adder circuit?

Do you mean :- how to get full adders by using half-adders?

For this question refer following answer -

A full-adder can be obtained by combining two half-adders and one or gate.

Details on full-adder and half-adder can be referenced from following link

http://www.fullchipdesign.com/fulladder.htm