0
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
Different between power transistor and transistor that used in small signal?
Power transistor can conduct large amount of currents through it, more than small signal transistor. power transistor has a vertical structure and small signal transistor has horizontal structure.In power transistor quasi saturation region is present which is absent in the small signal transistor. In power transistor there is a inculsion of drift layer which is not there in the small signal transistor. Power dissipation is less in power transistor and it is more in small signal transistor.
b.v.polytechnic,vasai
pushkar vaity.
Pseudo-random or random function on assembly?
WHY DO YOU NEED TO KNOW THE ANSWER ANYWAY. LOOK SOMEWHERE ELSE.LIKE GOOGLE
What is a roll off filter of a microphone?
The roll off filter removes low frequencies. Usually at about 75 HZ and bellow.
E1 = 4.44 f N1Øm (for primary)
E2 = 4.44 f N2Øm (for secondary)
What is mean by SOWA for cord?
Cord/Cable is resistant to Sunlight, Oil, Water, and the -A is a Flexibility designation.
Symbols of the electric circuit?
- there is a symbol of bulb,galvanometer,voltmeter,ammeter,gong,paperclip,switch,wire,solenoid,bulb and armature
A nonlinear resistance is a resistance which is different for different voltages ie current is not proportional to voltage. An example of this is the filament of an incandescent lamp.
In semiconductors, the relationship between the flow of electrical current and electrostatic potential across a p-n junction depends on a characteristic voltage called the thermal voltage, denoted VT.
How is the capacitor able to account for AC Ripples?
Ripple Voltage is voltage variation across the load and it is the AC component. To answer this question, consider a Half Wave rectifier with a smoothing capacitor: This rectifier will consist of a sinusoidal voltage source, an ideal diode, a capacitor in parallel with the load. At t=0, the voltage across capacitor = load voltage When the circuit is switched on, the capacitor is fully charged as the sinusoidal source reaches its peak. However, the sinusoidal nature causes the source voltage to decline after reaching the peak. This means that no current will flow through the diode. But the capacitor is still charged. So this will supply current to the load while it discharges. But during the discharging period (till the sinusoidal picks up again), the load voltage is an exponential function = peak voltage *exp-[(t - t')*resistance of load*capacitance] Now a key point is that the pulsating current is flowing through the diode to recharge the capacitor. Because of this constant charge and discharge of the capacitor in the cycle, the load voltage has AC ripples. At the same time load current is never zero and is directly prop to load voltage. The dc component >> ac component and the ripple voltage is greatly reduced by the capacitance esp a large one. You can minimize these by choosing a large capacitance. This is how a capacitor accounts for AC ripples. You can never actually rid these ripples even if you use a full-wave rectifier! Google search half - wave rectifier graphs on the ripples to understand this!! --- Sona
it means network operating center engineer, one who operates network.
Why are analog meters used in vehicles?
If you are cruising down the freeway, you can get about the same information on, say, your speed, if you look at an analog meter as a digital one. But if you are braking and your speed is changing, a digital meter will be "fluttering" as it continuously gets a new reading to post, and it won't be able to tell you how fast you're going. (This had to do with the way the sensors "sample" the speed to display it.) In the analog meter, the needle will be falling as you slow down, and the human brain has a better "grasp" of the "meaning" of the falling needle than it has of blinking numbers on a display. Certainly as the needle on an analog meter passes a specific mile-per-hour marker, you can see how fast you were going. But it is the value of the moving needle in the analog meter and the ability of the brain to "understand" it that makes it so much more effective than a digital display.
There is a wide selection of photosensitive devices that are available to the electronic designer. Whilst photo-diodes fulfil many requirements, phototransistors or photo transistors are also available, and are more suitable in some applications. Providing high levels of gain, and standard devices are low cost, these phototransistors can be used in many applications.
The idea of the photo transistor has been known for many years. William Shockley first proposed the idea in 1951, not long after the ordinary transistor had been discovered. It was then only two years before the photo transistor was demonstrated. Since then phototransistors have been used in a variety of applications, and their development has continued ever since.
Phototransistor structureAlthough ordinary transistors exhibit the photosensitive effects if they are exposed to light, the structure of the phototransistor is specifically optimised for photo applications. The photo transistor has much larger base and collector areas than would be used for a normal transistor. These devices were generally made using diffusion or ion implantation.Homojunction planar phototransistor structure
Early photo transistors used germanium or silicon throughout the device giving a homo-junction structure. The more modern phototransistors use type III-V materials such as gallium arsenide and the like. Heterostructures that use different materials either side of the p-n junction are also popular because they provide a high conversion efficiency. These are generally fabricated using epitaxial growth of materials that have matching lattice structures. These photo transistors generally use a mesa structure. Sometimes a Schottky (metal semiconductor) junction can be used for the collector within a phototransistor, although this practice is less common these days because other structures offer better levels of performance.
Heterojunction mesa-structure phototransistor
In order to ensure the optimum conversion and hence sensitivity, the emitter contact is often offset within the phototransistor structure. This ensures that the maximum amount of light reaches the active region within the phototransistor.
Phototransistor operationPhoto transistors are operated in their active regime, although the base connection is left open circuit or disconnected because it is not required. The base of the photo transistor would only be used to bias the transistor so that additional collector current was flowing and this would mask any current flowing as a result of the photo-action. For operation the bias conditions are quite simple. The collector of an n-p-n transistor is made positive with respect to the emitter or negative for a p-n-p transistor.The light enters the base region of the phototransistor where it causes hole electron pairs to be generated. This mainly occurs in the reverse biased base-collector junction. The hole-electron pairs move under the influence of the electric field and provide the base current, causing electrons to be injected into the emitter.
Phototransistor characteristicsAs already mentioned the photo transistor has a high level of gain resulting from the transistor action. For homo-structures, i.e. ones using the same material throughout the device, this may be of the order of about 50 up to a few hundred. However for the hetero-structure devices, the levels of gain may rise to ten thousand. Despite their high level of gain the hetero-structure devices are not widely used because they are considerably more costly to manufacture. A further advantage of all phototransistors when compared to the avalanche photodiode, another device that offers gain, is that the phototransistor has a much lower level of noise.One of the main disadvantages of the phototransistor is the fact that it does not have a particularly good high frequency response. This arises from the large capacitance associated with the base-collector junction. This junction is designed to be relatively large to enable it to pick up sufficient quantities of light. For a typical homo-structure device the bandwidth may be limited to about 250 kHz. Hetero-junction devices have a much higher limit and some can be operated at frequencies as high as 1 GHz.
The characteristics of the photo-transistor under different light intensities. They are very similar to the characteristics of a conventional bipolar transistor, but with the different levels of base current replaced by the different levels of light intensity.
There is a small amount of current that flows in the photo transistor even when no light is present. This is called the dark current, and represents the small number of carriers that are injected into the emitter. Like the photo-generated carriers this is also subject to the amplification by the transistor action.
Why the cathode in cathode ray tube is indirectly heated by the filament?
To create an electron cloud that can be shaped into a beam.
A router is a layer 3 device.In general, a Layer-3 switch (routing switch) is primarily a switch (a Layer-2 device) that has been enhanced or taught some routing (Layer 3) capabilities. A router is a Layer-3 device that simply do routing only. In the case of a switching router, it is primarily a router that may use switching technology (high-speed ASICs) for speed and performance (as well as also supporting Layer-2 bridging functions).
As illustration, here are some examples
Layer-2 switches
Cisco: Catalyst 2950, 2960 series
Layer-3 switches or routing switches
Cisco: Catalyst 3550, 3560, 3750, 4500, 6500 series
Juniper: EX series
Routers (with some bridging and/or security features) or switching routers
Cisco: 1800, 1900, 2600, 2800, 2900, 3700, 3800, 3900, 7200, 7600, ASR 1000 series
Juniper: MX series, J series, M series
No, graphite is not soft. In fact, if you find a graphite rock, it is extremely hard. It is often very colorful, though.
Previous year asked campus interview question papers in biomedical engineering asked in CTS?
biomedical engineer questions with answers
Electrical impedance is the total opposition to current flow. It includes both a resistive, or DC component and a reactive, or frequency-dependant component. Impedance is the same as resistance if the applied voltage is DC. For AC voltage, the reactive components opposition to current flow changes with frequency, so impedance is typically specified at a particular frequency.
What are the advantages of mimo over siso and simo?
it remove the problem of multipath fadding. it remove the problem of multipath fadding.
What is com terminal on a multimeter?
The com is your common terminal also the negative terminal where the black probe is pluged in. normally used on meter with 3 or more connectors and only the red probe change position
What is prncipal of transducer?
The basic principle of a transducer:
A transducer which converts a physical quantity to the electrical quantity.
