Electronics Engineering

Using a higher voltage reduces power losses during transmission.

• SDH and PDH are two digital hierarchies in which different line speeds (e.g. E1, T1, STM1) are categorized.
• PDH (plesiosynchronous digital hierarchy) was replaced by SDH (synchronous digital hierarchy) due to its drawback in synchronisation where plesio refers to nearlysynchronous.
• E1, T1 and J1 are generally categorized under PDH. STM1, OC3, STM4, OC12 etc. are categorized under SDH.
• E1 is used worldwide nowadays in 2G technologies except North America and Japan (who are using T1 and J1 respectively). It is the line speed of 2Mbps. But how this speed comes along? The derivation is as follows.
• The audio signals were sampled and converted to digital signal at 64kbps, since 1960s for digital transmission of voice calls. When 32 channels (30 assigned for voice channels and 2 channels for framing and signaling), with each having speed of 64kbps are put together (or we call multiplexing), a line speed of E1, i.e. 2Mbps is produced by having 32 x 64kbps = 2.048Mbps.
• T1 line, which transmits at 1.544 Mbps can be interconnected with E1 for international use.
• Having 3 different speeds (E1, T1 and J1), PDH was later replaced by SDH in order to standardize the speed, making only 1 standard speed worldwide, which is STM1 having the speed of 155.52Mbps.

E=sin(Theta);

You need to normalize the equation for the electric field of the half-wavelegnth dipole. recall E=sqrt(ExE*) where E* is the conjugate of the E field.

This is why you only get an eight shaped figure (or infinity symbol) when you plot it. you will get this figure if the dipole is placed in the axis of interest. e.g. if it is in the placed in the x axis, you will get an eighth in the x-y,x-z, but you will get a donut shape in the y-z (no angle to measure)

hope this helps a bit.

operating point of dc load line refers to point where there is no signal either no amplification use to take place as base current is zero(in case of common emitter configuration) and it is represented by Q.......

passive attacks : footprinting, trashing

active attacks : sniffing, social engineering

It's what happens when a battery is about to expire.

there are no good or bad conductor there are conductor ,semiconductor and isolator.

what is communication system explain with block diagram.

The term Microwave is a description of a high frequency radio wave in the range of 1 Gigahertz (One million cycles per second) to 40 gigahertz (40 million cycles per second). Radio waves at this frequency have the tenancy to reflect & refract making them useful for a wide number of applications.

Also since the radio wavelength is related to the frequency (frequency in Hertz divided by the speed of light in metres per second equals wavelength) the aerial size for this band is very small allowing for the use of exotic aerial systems such as dishes.

Dish aerials (antenna) are extremely efficient reflectors for microwave transmitters producing point to point links which can operate over many miles. Unlike High low and medium frequency Transmitters, microwave frequencies are not affected by the ionisation of the gas layers in the atmosphere. Therefore they tend to pass straight through the atmosphere rather than being reflected or refracted back to Earth. This makes them very useful for space communications and radio astronomy.

Microwaves do have some problems though. It is relatively expensive to generate high output at microwave frequencies. Also the nature of microwaves is that they do not pass through solid or grounded objects. This means that rain clouds can block the signal. Also at high power, microwaves excite water molecules, causing them to heat up (this is the principle of the microwave oven). Therefore inappropriate use can be hazardous to health.

Microwave are used to locate ships and planes, track weather systems, and determine the speeds of moving objects. They are the principal carriers of television, telephone, and data transmissions between stations on Earth and between the Earth and satellites.

Reverse voltage is voltage is applied in reverse. Instead of the positive voltage going into the anode lead of a component, it goes into the cathode lead of the component.

There are an infinite number of possible combinations to create an electric circuit.

It will simply not be possible to answer it correctly due to lack of information from absolutely all the developers around the world.

Even by limiting an answer to smaller circuits, this question is a challenge.

Even the simple light bulb is an electric circuit. How many different bulbs don't we find around the world these days? We have fluorescent bulbs, low voltage bulbs, high voltage bulbs, metal halide bulbs, halogen bulbs, this most likely in the thousands of different varieties from different manufacturers.

I would simply count on many many millions of different electric circuits. A lot of which would be similar work-wise, but still different maybe only by color.

This is only an educated guess that is in the area of many million's+ and then some.

By combining parts in order to make other circuits, the number grows unfathomable large pretty soon. The question only asks about what have been mad. Not what can be made. By this, we know the number can not be infinite, but we know the number to be large.

Each house around the world is an individual electric circuit. Each being different, however some more than others. We are 5 Billion people on this planet of ours. If there are 5 people in each house, then there must be 1 Billion houses with each a slightly different electrical circuit.

This may because specs of dust can cause activation of the detector as it has the same effect as smoke. Spiders also can crawl into the sensors which does the same thing- same way with deodrant, paintfumes etc. It also may be because the smoke detector is just faulty.

In FM the carrier is still present and the power is still there, at a constant amplitude at the transmitter. It's only the frequency of the carrier that alters, in time with the audio applied to it. The louder the sound the further the frequency shifts.

High frequency is used because of the the size of antennas used to transmit and receive the communications signal. The higher the frequency the smaller the antenna.

Well, yes they do. Any amplification adds noise to the signal. Some of this can be removed but the effects are cumulative. Imagine making a copy of a piece of music by an analog technique. Then making a copy from that copy, etc. You get more and more noise added to the system, even when the amplification is one. In digital systems, the music (or whatever) is made of bits that are either there or not. Cleaning up the bits is very easy. Perfect copies are typical.

You would use a supply bypass capacitor in a common collector amplifier...

It's necessary, to give the positive supply rail a direct AC connection to ground. Without it, I don't think the amplifier would work properly. However, if you're using a power supply and not a battery, then chances are that it HAS a big capacitor inside it, eliminating the need for any external capacitor.

Here are a couple. Assuming everything is "normal" here, if you drop a bagel in the toaster and turn it on by pushing the lever down, the AC current the toaster uses (draws) will stabilize after a few seconds and stay constant. If you turn on your car's headlights, each lamp will draw a constant current from the DC source after a few seconds of "warm up" time. Those are examples of constant electric current.

Thanks for your contribution and thoughts but you CAN use a 4.2 volt charger for a 3 volt battery.

Jyot


No. You should not use a 4.2V charger for a 3V battery. The charger is specifically designed for the battery. Attempting to use a non rated configuration, unless the charger states clearly on its label that it can handle the 4.2V battery, could result in overcharge, overheat, even fire.

Even attempting to place a resistor or zener diode in series with the battery is not a good idea, because some chargers use the voltage/time curve to sense when the battery is fully charged, and this will bias the results.

Basically a diode is a combinstion of pN junction but the transistor is made with three terminals EMITTER,, BASE ,, JUNCTION.. and diode is just a combination of positive and negative terminal . diode and transistors are both used as a switch .. but a transistor is more widly udes than a diode. and diode has also very important in electronics DIGITAL SYSTEM to make the screen's ..and transistors are used in amplifiers the group of transistors make an amplifier . and we use a diode in seven segment display ....diode is small and carry less current due to its small size but transistor get large current.

A2

A diode has two connections. It allows current to flow in one direction and not in the other. They are used for rectification in power supplies, detection of AM radio, blocking of current etc.

A Transistor has three connections. Current is controlled between the emitter and collector, by a small current on the base. They are used as switches, amplifiers and regulators.

first decide the numbar of bits...for four bits write the varoiurs combination of each bit.

for 4 bits 2^4=16 combination starting from 0000-1111.

similarly you will get 4 bit gray code by ex-oring (u may find this conversion in any book digital book).

now draw k-map for each out put bit

binary gray

0000 0000

0001 0001

0010 0011

...... ......

....... ......

1111 0000

consider case for 0010 to 0011.

lsb will be g0(1) and msb will be g3.(0)

each bit should be considered as an output and k-map has to be drawn for each output,viz g0,g1,g2,g3.

after implementing this ,realise the output expression using gates.(k map will give simplified output).

this is basic operation...but if u plan to implement in an project try getting an ready made IC.

A: Definitely NOT it must follow its linear load region a close loop of approaching infinity will certainly be inclined to be not stable

Short circuit voltage is the voltage that has to be applied to the primaries of a transformer, so that the nominal current flows through the secondaries, when they are shorted. This value is important, if transformer secondaries shall be used in parallel. Ideally all transformers with parallel secondaries should have the same short circuit voltage. When their short circuit voltages are different, the transformer with the lower short circuit voltage will be loaded more than their relationship of power ratings would predict. The short circuit voltage is also important in the design of a transformer, because it predicts, how much the secondary voltage will drop at nominal output current. This knowledge helps the designer to find out, how many further windings the secondary needs for a certain voltage in relation to an ideal transformer. Short circuit voltage is also known as impedance voltage.

The load current is made to flow through the thermal overload relay, which is actually a bimetalic strip. Beyond a prespecified current the bimetalic strip tend to deflect due to heat (thermal effect) thus cutting off the circuit and hence it acts as an over load relay protection.