Electronics Engineering

Frequencies of an image: roughly speaking they are a measure

of the amount by which the gray value changes with the

distance.

High frequency components are characterized by large

changes in gray values over small distances. e.g. edges, noise.

Low frequency components are characterized by little

changes in gray values over small distances. e.g. backgrounds,

skin texture.

silicon ang germanium there are two types of transistor \ 1. PNP 2. NPN silicon ang germanium there are two types of transistor \ 1. PNP 2. NPN

There are none except for the fact if the if the input signal has variations in value, with no filtering, the digital readouts can become a guess to read.

Analog meters will average these variations as a wiggle of the needle so that the reading changes in a slower manner which is easier to read.

Dc Power Supplies converts AC to DC Two Main types 1)Linear : A simple circuit with diodes and capacitors 2)Switched Mode: sampling technique is used to convert AC to DC.

in the case of communication through gsm technology we transmit our voice frequency to somewhere from the origin. normally human voice frequency lays between 300-3400khz. if all the people tends to transmit their voice, the signal wil be distroyed due to interference. also theoretically it need a very long antenna to transmit a low frequency. therefore it is necessary to modulate each and every signal to a high frequency carrier to transmit without any interference and make possible communication

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WHAT IS TRASISTER WORKING

It is the addition of impurities to a semi-conductor in order improve their electrical conductivity.

Snubber circuits are used for semiconductor switching devices such as transistors, SCRs, etc. When a switching device changes its state from ON-state to OFF-state, the impedandce of the device abruptly jumps to a very high level, blocking the current. But the current still tends to keep flowing through the switch, which induces a high voltage across the switch. The faster the current decreases, the higher the induced voltage becomes. It may reach to sufficiently high level to destroy the switch. If the switch is unable to withstand the high induced voltage, it will be destroyed, and can no more block the current as an OFF-state switch. To avoid this, an auxiliary network is connected across the switch that prevents the induced voltage from going too high. The network is called a snubber. Conversely, when a switching device changes its state from OFF-state to ON-state, the impedance of the device abruptly goes down to nearly zero, allowing current to flow freely. The problem in this case is that the current does not start to flow uniformly through the switch. This is because the switch does not recover its conductivity over the whole its cross-sectional area simultaneously. Some part of the area may be first open, and the current flow is concentrated to this relatively small portion of the switch, which may cause overheating and eventually failure. Thus some semiconductor switches should be protected from too fast increase of current. This is another function of a snubber. In view of above discussion, the snubber circuit is someting like a "bumper." It alleviates rise of voltage when the switch is turning OFF, and alleviates rise of current when the switch is turning ON, to a safe level.

Dual port ROM is a one, where data from two different address's can be read simultaneously, unlike single port where data from only one address can be read.

The working principle of the ATM is to offer cash access virtually anywhere. An compatible card is input, a PIN code entered, account balance checked, and money dispensed.

E.C. Went

A Device is said to be active if...

(i) It is a source of Power in the circuit...

(ii) It amplifies any voltage or current in a circuit...

(iii) It acts as a switch ie., has modes equivalent to ON and OFF...

e.g., transistor amplifies and can also act as a switch...

From what I can remember it's:

|R(measured)-R(real)|/(R(real))*100%

This is hard to explain. AM means amplitude modulation, while ASK is amplitude-shift keying. AM is usually analog as it is modulated based on the strength of the signal, though you can use it to send a digital signal. ASK represents digital data as variations in the amplitude of a carrier wave. Any digital modulation technique will represent the data using a finite number of different signals. While AM is used mostly for radio and television, ASK is used for telegraph signals, transmission across telecommunications equipment, and fiber optics.

ic made from bjt is known as bipolar ic

Pottant is the material, usually some form of silicone, that holds crystalline solar cells in place inside their modules.

our raight

By connecting a resistor in parallel to an electric motor to control its speed is bad practice. One would then be using the internal resistance of your source to reduce the voltage that drive the motor. In some cases it is not only insufficient but also dangerous because you might short circuit or overload your source.

In very low power applications with small motors, having a series resistor will work just fine (resistor in line with the motor)

With higher power AC circuits a choking coil may be used. Then you rely on the inductance of the coil to increase impedance without converting all the unused energy into heat.

The problem with resistors are that if your motor need to run on 6V in order to draw 1 ampere to produce 6 watt power and you obtained that by using a 12V supply with a resistor in series. Then the supply will deliver 12V x 1A = 12W and the motor will use 6V x 1A = 6W, what happens to the other 6W? it is dissipated by the resistor, the resistor will convert that unused energy into heat. This method is not very energy efficient and can become difficult to keep the resistor cool.

Ideally when larger motors are used. The use of PWM (Pulse Width Modulation) becomes essential. PWM allow you to switch the motor on and off at high frequency. When the power is on and no resistance is in series. Then all energy goes to the motor to be effectively used resulting in high efficiency. Then, when the supply is in off state, then no power is consumed at all. This will also result in very low energy loss. Thus, regardless whether the power is on or off there is always very little energy wasted.

If 12W is delivered when the supply is on and 0W is delivered when it is off. Should the pulse be on 50% of the time and off for the other 50% of the time. We will call it a 50% duty cycle (d.c.). The average power delivered will be 6W since it only deliver 12W half of the time. But since the 12W and 0W periods are both low energy loss states due to low resistance. The average 6W will also be delivered at high efficiency and almost no extra energy will be wasted on heat.

It makes sense, when you want to reduce the speed of a 100kW motor. Then using a resistor with a 50 000 W rating, baring in mind that 50 000W may be dissipated as heat. Then the "cooling towers" required to keep the resistor cool will be a bit absurd. Paying for an extra 50 000 W, what is not used will not do your business any good either.

You can't.

If you know the voltage (volts) and current (amperes), you can convert to power (watts), but power is not energy. Power is the rate of energy (joules per second). You need to know the time as well to determine energy.

Yes. 1500 mA = 1.5 A

Through LAN bytes are not only send, they are also received. LAN is the acronym for Local Access Network ... basically a computer network. In a network bytes are sent and received.

Radar!

The advantages of a UJT include low cost, a negative resistance characteristic, and a low value of triggering current. The main disadvantage is the inability to provide decent amplification.

the meaning of klm

It really depends what type of research. For example you could be researching about something that has a two sided opinion, and if the article you're reading is bias to your side of opinion then it would help you.