Electronics Engineering

Say there are n possible input sequences that is A1 to An. Coded sequence B is transmitted. At receiver end due to noise sequence R is obtained. Than we will calculate P(Ai/R) for i = 1 to n. Decoded sequence A for which the probability is maximum is decoded maximum likelihood sequence.

It is here at this website. www.mosfetdiagrams.co.uk/varibles

SCR is bipolar device since current is due to both electrons as well as holes.

IGBT and BJT are bipolar devices as the name suggest. Meaning of bipolar device both electrons and holes leads to current unlike FET where either electron or hole causes current.

A semiconductor has an energy band (a range of energy levels) that is forbidden -- ideally void of charged particles at all temperatures. Practically, at low temperatures (T < 40 K for silicon), the probability of finding a free charge carrier outside the forbidden gap is nearly nil. When the temperature is increased, the probability of finding a free charge carrier outside the forbidden gap increases, but the net charge is still zero (negative charge exactly cancels positive charge). However, an intrinsic semiconductor (pure or undoped) is just a resistor of little importance (other materials are cheaper and better-controlled than a semiconductor).

When we introduce foreign atoms into a semiconductor (the process is called doping), we change its electrical properties -- it has a lot more free charge carriers than an intrinsic semiconductor, although again, the net charge is zero. The total charge of free carriers is balanced by immobile ions of equal and opposite total charge. For example, boron and indium will be used to dope silicon p-type; phosphorus and arsenic will be doping silicon n-type. I am quoting boron, phosphorus, and silicon as examples from hereon.

p-type doping is a process where a silicon atom in the lattice is replaced by a boron atom. A Boron atom has 3 electrons in the outer shell, compared with an electron occupancy of 4 for a silicon atom. So a Boron atom provides a vacancy for any free electrons to occupy with a little effort, when an electron chances to be nearby (the four boron-silicon covalent bonds needs 8 electrons to be stable, but only 7 are provided). The net charge of the material is still zero. More about from where the free electron is coming.

n-type doping is using a phosphorus atom to replace a silicon atom. A phosphorus atom has 5 electrons in the outer shell. So a phosphorus atom provides an electron that can be freed with a little effort (the four phosphorus-silicon covalent bonds only need 8 electrons to be stable, each atom needing only to contribute four electrons; the 9th electron will be loosely bound). The net charge of the material is still zero. Where can the electron go?

Magic happens when a p-type silicon is brought in contact with an n-type silicon to form a pn junction. The excess electron vacancies (holes) in p-Si now can exchange with the excess electrons in n-Si, but the net charge of the p-n silicon entity is still zero. However, microscopically, a depletion region is formed at the pn junction, where excess carriers can cross over to the other side. In the p-Si, excess electrons from the n-Si start filling up the holes (the lack of the 8th outer-shell electron to form the four stable boron-silicon covalent bonds) and negatively-charged boron atoms are formed. In the n-Si, excess holes from the p-Si start swallowing up the loosely-bound electrons (the 9th electron in the outer shell) of phosphorus atoms and positively-charged phosphorus atoms are formed. Once formed, and in the absence of an electric field, the depletion region now presents an energy barrier to any further carrier movement and a steady state results -- no net current in the pn junction.

Fade rate is the time to fade a certain amount. For example, Multipath fading on a microwave link may occur at 100dB/sec.

Fade depth is the reduction from the normal received level, measured in dB.

place the multimeter on the diode. then connect the plobs to the hv diode. it can only conduct in one direction, not both ways. good luck

I size of the object is comparable to wavelength, it will cause error. In high frequency wavelength is very low. So small-small objects will also cause interference, thereby increasing attenuation. Waveguides are hollow metals. Thus wave does not go out and stay inside. Metals does not cause any attenuation. Propagation of EM wave in waveguide is similar to light in optical fiber.

a video machine made of caramel

These do:

TV set

stereo

automotive computer

desktop PC

digital meter

1

Assuming the motor runs at about 3000 RPM, The speed must be reduced by factor of about 200 for 15RPM.

Two sets of pulleys or gears would be best. Gears with a chain would not be good due to the high motor speed.

You could get 180:1 by putting a 2" pully on the motor, and running a belt to a 30" pulley which is on a shaft along with another 2" pulley, and run that pulley to another 24" pulley.

If the barrel is well-mounted and freely turns, you could use it as the second pulley, since it has a 24" approximate diameter.

You can also use three sets of pulleys, making it esier to find them.

example:

2" motor to 12" on shaft 1

2" on shaft 1 to 12" on shaft 2

2" on shaft 2 to a 10" or 12" one driving the barrel.

Consider buying a used worm gear reduction drive to save alot of this trouble. The motor can drive it directly and they come in different ratios.

A lumped network is made of physically separated R,L and C elements.harjinder singh is made by

An insulated-gate bipolar transistor (IGBT) uses relatively high frequency switching and pulse width modulation (PWM) technology for voltage and current regulation whilst a silicon controlled rectifier (SCR) uses relatively low frequency switching and phase shift technology.

Because of the relatively high frequency of operation, the transformers used in circuits having IGBT scan be much smaller in size and lighter in weight, therefore overall a IGBT-based power control circuit can be made much smaller in size, lighter in weight, more energy efficient and more cost effective compared to SCR-based control ciruits.

Apart from those advantages, because the cost of manufacturing IGBTs is now lower than SCRs, IGBTs are rapidly replacing SCRs for power control applications.

give answer how to control the speed of dc motor using bridge rectifier ?

ANSWER: A bridge rectifier by itself does not control anything it merely convert AC into DC. the controlling is done by other means SCR TRIACS AND SERVO loop

Schmitt trigger converts any type of waveform (such as sine,triangular.........)to square wave.So it is called Square wave converter.

the symbol of a capacitor looks sumthing like this...

C

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spectrum analyser is single channel and cannot find ratio of phase and magnitude

A watt hour is a unit of energy, not time -so you cannot ask how 'long' it is. The time taken to consume a watt hour of energy depends upon the rate (i.e. the power) at which it is consumed, expressed in watts. A watt hour is defined as the amount of energy consumed, over a period of one hour, at the rate of one watt.

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The difference between a latch and a flip-flop is that a latch does not have a clock signal, whereas a flip-flop always does.

Apart from the clock signal difference,

~ Latch is a level sensitive device while flip-flop is an edge sensitive device.

~ Latch is sensitive to glitches on enable pin, whereas flip-flop is immune to glitches.

~ Latches take less gates (also less power) to implement than flip-flops.

~ Latches are faster than flip-flops.

First, that's not enough information to calculate anything. You need to specify the voltage, too. I'll assume 120 VAC.

Second, it's kilowatt-hours, not kilowatts. kW is a unit of power, kWh is a unit of energy. They are not at all the same thing. You'd need a pretty big freezer to draw 242,000 W. :)

So 242 kW·hour / year / 120 V = 0.2 A

the final stage of a power amp is a current amplifier in a bipolar design and a voltage amp in a FET design.

So as opposed to a BJT transistor (which has a large but measurable input impedance) a Mosfet has even larger (presumably infinite) impedance. The reason is because of a small non-conducting zone that exists between the Gate side and the Drain-Source side. It acts as a small capacitor (which capacitors have infinite resistance), and the electromagnet field produced is what drives current between Source and Drain. Now, why is this desirable? In the case of BJT's there is a small current that flows into the base, essentially drawing small but existent power from the circuit connected at the Base. It is more ideal to have a transistor that completely separates the current of the control circuit and the current in the circuit being switched/supplied. Simply, it means its more efficient. When BJT transistors are turned off, power is still being used. The same isn't necessarily true for Mosfet transistors.