Lost your password? Please enter your email address. You will receive a link and will create a new password via email.
Please briefly explain why you feel this question should be reported.
Please briefly explain why you feel this answer should be reported.
Please briefly explain why you feel this user should be reported.
If you are using C language to implement the heterogeneous linked list, what pointer type should be used?
The heterogeneous linked list contains different data types, so it is not possible to use ordinary pointers for this. For this purpose, you have to use a generic pointer type like void pointer because the void pointer is capable of storing a pointer to any type.
The heterogeneous linked list contains different data types, so it is not possible to use ordinary pointers for this. For this purpose, you have to use a generic pointer type like void pointer because the void pointer is capable of storing a pointer to any type.
See lessWrite the C program to insert a node in circular singly list at the beginning.
#include<stdio.h> #include<stdlib.h> void beg_insert(int); struct node { int data; struct node *next; }; struct node *head; void main () { int choice,item; do { printf("\nEnter the item which you want to insert?\n"); scanf("%d",&item); beg_Read more
See lessDefine the queue data structure.
A queue can be defined as an ordered list that enables insert operations to be performed at one end called REAR and delete operations to be performed at another end called FRONT.
A queue can be defined as an ordered list that enables insert operations to be performed at one end called REAR and delete operations to be performed at another end called FRONT.
See lessList some applications of queue data structure.
Applications of the queue are given as follows: Queues are widely used as waiting lists for a single shared resource like a printer, disk, or CPU. Queues are used in the asynchronous transfer of data (where data is not being transferred at the same rate between two processes) for eg. pipes, file IO,Read more
Applications of the queue are given as follows:
- Queues are widely used as waiting lists for a single shared resource like a printer, disk, or CPU.
- Queues are used in the asynchronous transfer of data (where data is not being transferred at the same rate between two processes) for eg. pipes, file IO, and sockets.
- Queues are used as buffers in most applications like MP3 media players, CD players, etc.
- Queues are used to maintain the playlist in media players to add and remove the songs from the playlist.
- Queues are used in operating systems for handling interrupts.
See lessList the area of applications where stack data structure can be used?
Expression evaluation Backtracking Memory Management Function calling and return
- Expression evaluation
- Backtracking
- Memory Management
- Function calling and return
See lessWhat is the difference between file structure and storage structure?
File Structure: A hard disk or external device (such as a USB), stores data that remains intact till manually deleted. Such data representation into secondary or auxiliary memory is called a file structure. Storage Structure: In this type of structure, data (variables, constants, etc.) are stored inRead more
- File Structure: A hard disk or external device (such as a USB), stores data that remains intact till manually deleted. Such data representation into secondary or auxiliary memory is called a file structure.
- Storage Structure: In this type of structure, data (variables, constants, etc.) are stored in the main memory, i.e. RAM, and is deleted once the function that uses this data has been completed.
See lessChoosing power supply, how to get the voltage and current ratings?
Voltage Rating If a device says it needs a particular voltage, then you have to assume it needs that voltage. Both lower and higher could be bad. At best, with lower voltage the device will not operate correctly in a obvious way. However, some devices might appear to operate correctly, then fail inRead more
Voltage Rating
If a device says it needs a particular voltage, then you have to assume it needs that voltage. Both lower and higher could be bad.
At best, with lower voltage the device will not operate correctly in a obvious way. However, some devices might appear to operate correctly, then fail in unexpected ways under just the right circumstances. When you violate required specs, you don’t know what might happen. Some devices can even be damaged by too low a voltage for extended periods of time. If the device has a motor, for example, then the motor might not be able to develop enough torque to turn, so it just sits there getting hot. Some devices might draw more current to compensate for the lower voltage, but the higher than intended current can damage something. Most of the time, lower voltage will just make a device not work, but damage can’t be ruled out unless you know something about the device.
Higher than specified voltage is definitely bad. Electrical components all have voltages above which they fail. Components rated for higher voltage generally cost more or have less desirable characteristics, so picking the right voltage tolerance for the components in the device probably got significant design attention. Applying too much voltage violates the design assumptions. Some level of too much voltage will damage something, but you don’t know where that level is. Take what a device says on its nameplate seriously and don’t give it more voltage than that.
Current Rating
Current is a bit different. A constant-voltage supply doesn’t determine the current: the load, which in this case is the device, does. If Johnny wants to eat two apples, he’s only going to eat two whether you put 2, 3, 5, or 20 apples on the table. A device that wants 2 A of current works the same way. It will draw 2 A whether the power supply can only provide the 2 A, or whether it could have supplied 3, 5, or 20 A. The current rating of a supply is what it can deliver, not what it will always force thru the load somehow. In that sense, unlike with voltage, the current rating of a power supply must be at least what the device wants but there is no harm in it being higher. A 9 volt 5 amp supply is a superset of a 9 volt 2 amp supply, for example.
Replacing Existing Supply
If you are replacing a previous power supply and don’t know the device’s requirements, then consider that power supply’s rating to be the device’s requirements. For example, if a unlabeled device was powered from a 9 V and 1 A supply, you can replace it with a 9 V and 1 or more amp supply.
Advanced Concepts
The above gives the basics of how to pick a power supply for some device. In most cases that is all you need to know to go to a store or on line and buy a power supply. If you’re still a bit hazy on what exactly voltage and current are, it’s probably better to quit now. This section goes into more power supply details that generally don’t matter at the consumer level, and it assumes some basic understanding of electronics.
-
-
-
-
See lessRegulated versus Unregulated
Unregulated
Very basic DC power supplies, called unregulated, just step down the input AC (generally the DC you want is at a much lower voltage than the wall power you plug the supply into), rectify it to produce DC, add a output cap to reduce ripple, and call it a day. Years ago, many power supplies were like that. They were little more than a transformer, four diodes making a full wave bridge (takes the absolute value of voltage electronically), and the filter cap. In these kinds of supplies, the output voltage is dictated by the turns ratio of the transformer. This is fixed, so instead of making a fixed output voltage their output is mostly proportional to the input AC voltage. For example, such a “12 V” DC supply might make 12 V at 110 VAC in, but then would make over 13 V at 120 VAC in.
Another issue with unregulated supplies is that the output voltage not only is a function of the input voltage, but will also fluctuate with how much current is being drawn from the supply. A unregulated “12 volt 1 amp” supply is probably designed to provide the rated 12 V at full output current and the lowest valid AC input voltage, like 110 V. It could be over 13 V at 110 V in at no load (0 amps out) alone, and then higher yet at higher input voltage. Such a supply could easily put out 15 V, for example, under some conditions. Devices that needed the “12 V” were designed to handle that, so that was fine.
Regulated
Modern power supplies don’t work that way anymore. Pretty much anything you can buy as consumer electronics will be a regulated power supply. You can still get unregulated supplies from more specialized electronics suppliers aimed at manufacturers, professionals, or at least hobbyists that should know the difference. For example, Jameco has wide selection of power supplies. Their wall warts are specifically divided into regulated and unregulated types. However, unless you go poking around where the average consumer shouldn’t be, you won’t likely run into unregulated supplies. Try asking for a unregulated wall wart at a consumer store that sells other stuff too, and they probably won’t even know what you’re talking about.
A regulated supply actively controls its output voltage. These contain additional circuitry that can tweak the output voltage up and down. This is done continuously to compensate for input voltage variations and variations in the current the load is drawing. A regulated 1 amp 12 volt power supply, for example, is going to put out pretty close to 12 V over its full AC input voltage range and as long as you don’t draw more than 1 A from it.
Universal input
Since there is circuitry in the supply to tolerate some input voltage fluctuations, it’s not much harder to make the valid input voltage range wider and cover any valid wall power found anywhere in the world. More and more supplies are being made like that, and are called universal input. This generally means they can run from 90-240 V AC, and that can be 50 or 60 Hz.
Minimum Load
Some power supplies, generally older switchers, have a minimum load requirement. This is usually 10% of full rated output current. For example, a 12 volt 2 amp supply with a minimum load requirement of 10% isn’t guaranteed to work right unless you load it with at least 200 mA. This restriction is something you’re only going to find in OEM models, meaning the supply is designed and sold to be embedded into someone else’s equipment where the right kind of engineer will consider this issue carefully. I won’t go into this more since this isn’t going to come up on a consumer power supply.
Current Limit
All supplies have some maximum current they can provide and still stick to the remaining specs. For a “12 volt 1 amp” supply, that means all is fine as long as you don’t try to draw more than the rated 1 A.
There are various things a supply can do if you try to exceed the 1 A rating. It could simply blow a fuse. Specialty OEM supplies that are stripped down for cost could catch fire or vanish into a greasy cloud of black smoke. However, nowadays, the most likely response is that the supply will drop its output voltage to whatever is necessary to not exceed the output current. This is called current limiting. Often the current limit is set a little higher than the rating to provide some margin. The “12 V 1 A” supply might limit the current to 1.1 A, for example.
A device that is trying to draw the excessive current probably won’t function correctly, but everything should stay safe, not catch fire, and recover nicely once the excessive load is removed.
Ripple
No supply, even a regulated one, can keep its output voltage exactly at the rating. Usually due to the way the supply works, there will be some frequency at which the output oscillates a little, or ripples. With unregulated supplies, the ripple is a direct function of the input AC. Basic transformer unregulated supplies fed from 60 Hz AC will generally ripple at 120 Hz, for example. The ripple of unregulated supplies can be fairly large. To abuse the 12 volt 1 amp example again, the ripple could easily be a volt or two at full load (1 A output current). Regulated supplies are usually switchers and therefore ripple at the switching frequency. A regulated 12 V 1 A switcher might ripple ±50 mV at 250 kHz, for example. The maximum ripple might not be at maximum output current.
What are the factors that cause intersymbol interference (ISI)?
Inter symbol interference is essentially caused by the dispersion of the channel. It can be avoided by leaving enough space in between the transmitted symbols. An obvious drawback of this primitive approach is that the throughput will decrease. A smarter method is to use an equalizer, which acts likRead more
What is faraday rotation? Explain the working of Gyrator and Isolator?
Faraday Rotation A linearly polarized wave propagates through the ferrite in the direction of bias, and the polarization undergoes rotation proportional to the length of the ferrite. This phenomenon is called Faraday rotation. Faraday rotation is a non-reciprocal effect. Isolator The isolator is a tRead more
Faraday Rotation
A linearly polarized wave propagates through the ferrite in the direction of bias,
and the polarization undergoes rotation proportional to the length of the ferrite. This
phenomenon is called Faraday rotation. Faraday rotation is a non-reciprocal effect.
Isolator
The isolator is a two-port non-reciprocal lossy device having unidirectional transmission characteristics:
The essential aspects of this passive device are
1. There is no attenuation when the wave propagates from port 1 to port 2.
2. When the wave propagates from port 1 to port 1 the attenuation is infinity.
The input card is in y-z plane¸ the dominant mode wave wherein the E-field vector is vertical traveling from left to right passes through resistive vane without
attenuation and enters the ferrite rod where it undergoes Faraday rotation of 450
clockwise. The wave again undergoes a rotation 450 in the anti-clockwise direction due to the twisted waveguide and the E-field vector at the output is vertical. The horizontal resistive vane does not affect the E-field as the same is vertical to its plane. Therefore the wave traveling from left to right pass though without any attenuation. Whereas the dominant mode wave entering from the right and traveling to the left undergoes a rotation 450 in the anti-clockwise direction due to the twisted waveguide. As it passes through the ferrite rod it again undergoes a rotation 450 in the anticlockwise direction and the E-field vector becomes horizontal. The resistive vane at the output which is in the horizontal plane opposes the energy as the E-filed vector is parallel to it. Therefore there is no output.
Gyrator
A gyrator is defined as a two-port device that has a relative difference in phase shift of 180o for transmission from port 1 to port 2 as compared with phase shift for transmission from port 2 to port 1. A gyrator may be obtained by employing the nonreciprocal property of Faraday rotation. The figure given below illustrates a typical microwave gyrator. It consists of a rectangular guide with a 90o twist connected to a circular guide. This in turn is connected to another rectangular guide at the other end. The two rectangular guides have the same orientation at the input ports. The circular guide contains a thin cylindrical rod of ferrite with the ends tapered to reduce reflections. A static axial magnetic field is applied so as to produce 90o Faraday rotation to the TE11 dominant mode in the circular guide.
Consider a wave propagating from left to right. In passing through the twist the plane of polarization is rotated by 90o in a counterclockwise direction. If the ferrite produced an additional 90o of rotation, the total angle of rotation will be 180o, as indicated in the figure above. For a wave propagating from right to left, the Faraday rotation is still 90o in the same sense. However, in passing through the twist, the next 90o of rotation is in a direction to cancel the Faraday rotation. Thus for transmission from port 2 to port1, there is no phase shift.
See lessChannel length modulation
CHANNEL LENGTH MODULATION Channel length modulation (CLM) is an effect in field-effect transistors, a shortening of the length of the inverted channel region with an increase in drain bias for large drain biases. The result of CLM is an increase in current with drain bias and a reduction of output rRead more
CHANNEL LENGTH MODULATION
Channel length modulation (CLM) is an effect in field-effect transistors, a shortening of the length of the inverted channel region with an increase in drain bias for large drain biases. The result of CLM is an increase in current with drain bias and a reduction of output resistance. It is one of several short-channel effects in MOSFET scaling. It also causes distortion in JFET amplifiers.
To understand the effect, first, the notion of pinch-off of the channel is introduced. The channel is formed by the attraction of carriers to the gate, and the current drawn through the channel is nearly a constant independent of drain voltage in saturation mode. However, near the drain, the gate and drain jointly determine the electric field pattern. Instead of flowing in a channel, beyond the pinch-off point, the carriers flow in a subsurface pattern made possible because the drain and the gate both control the current. In the figure at the right, the channel is indicated by a dashed line and becomes weaker as the drain is approached, leaving a gap of uninverted silicon between the end of the formed inversion layer and the drain (the pinch-off region).
As the drain voltage increases, its control over the current extends further toward the source, so the uninverted region expands toward the source, shortening the length of the channel region, the effect called channel-length modulation. Because resistance is proportional to length, shortening the channel decreases its resistance, causing an increase in current with an increase in drain bias for a MOSFET operating in saturation. The effect is more pronounced the shorter the source-to-drain separation, the deeper the drain junction, and the thicker the oxide insulator.
In the weak inversion region, the influence of the drain analogous to channel length modulation leads to poorer device turn-off behavior known as drain-induced barrier lowering, a drain-induced lowering of the threshold voltage.
See lessIn bipolar devices, a similar increase in current is seen with increased collector voltage due to base-narrowing, known as the Early effect. The similarity in effect upon the current has led to the use of the term “Early effect” for MOSFETs as well, as an alternative name for “channel-length modulation”.
The effect of channel-length modulation upon the MOSFET output resistance varies both with the device, particularly its channel length, and with the applied bias. The main factor affecting the output resistance in longer MOSFETs is channel length modulation as just described. In shorter MOSFETs, additional factors arise such as: drain induced barrier lowering (which lowers the threshold voltage, increasing the current and decreasing the output resistance), velocity saturation (which tends to limit the increase in channel current with drain voltage, thereby increasing the output resistance) and ballistic transport (which modifies the collection of current by the drain and modifies drain induced barrier lowering so as to increase the supply of carriers to the pinch-off region, increasing the current and decreasing the output resistance).