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Is a microphone a input device?
Yes a microphone is an input device. Input/output devices are determined by the direction of the signal being transfered. If the signal is being sent to the Case (main part of the computer that does all the work) then the device is classified as an input device and vice versa. Since the signal from the microphone is sent to the Case, the microphone is "inputting" information into the computer.
Why dc output voltage of a bridge rectifier varies with the load current?
aA A: the output of a Bridger's rectifier will always follows proportionally to the load since it does not regulate the output it merely transform AC TO DC '
For how many degrees of an input sine wave does a class B amplifier conduct?
The actual answer is 360 degrees, that is, a class B amplifier will conduct for the entire 360 degrees of an input sine wave. However, the interesting part is how this is accomplished. For a "pure" class B amplifier, each of the two output power devices will conduct for 180 degrees of the total 360 degrees of a complete sine wave. This is because in a class B amplifier, each of the output devices is biased so that it is off when the input signal is zero. When the input signal goes positive, one of the output devices will conduct. Assuming there is no overall phase inversion in the amplifier, this would be the "upper" device that is connected to the positive voltage rail. In a typical solid state audio power amplifier, this device is usually an NPN transistor or power MOSFET. The "lower" device, typically connected to the negative voltage rail, will conduct when the input signal goes negative. This device will typically be a PNP transistor in a solid state amplifier, or a power MOSFET. There are many possible configurations for class B amplifiers. For example, with vacuum tube amps, there is usually only a positive voltage supplied to the output stage, and the two output tubes are identical types. Instead of connecting the lower tube to a negative rail, it is usually connected to ground, but since we are interested in AC amplification, and also since an output transformer is required to couple tube output stages to low impedance loads such as loudspeakers, this doesn't present a problem. The output transformer will have a center tap where the positive output stage voltage is connected, and each of the output tubes will conduct in alternating fashion, similarly to the output of a solid state amp. In fact, early solid state audio amps also used output transformers, and they typically also used two NPN transistors for output devices, in contrast to modern designs that use symmetrical matched pairs of NPN/PNP. At that time it was difficult to obtain high power matched pairs, whereas high power NPNs were relatively easy to obtain. A variation that is often used to obtain more power is the doubling of output devices by operating them in parallel to obtain higher current gain. It is possible to see six, eight, or even more devices operating in this way, but it will almost always be in multiples of two. Nevertheless, no matter what the variations, a class B amplifier will always conduct for 360 degrees of an input sine wave. There is an important qualification on this, however. A true class B amplifier is almost never seen, due to a problem called "crossover distortion." This occurs because any output device has a nonlinear region during turn-on from zero conduction. While the input signal is beginning to go positive, for example, the output device will not "follow" the input signal in a proportional manner. To overcome the distortion caused by this, most audio amps are operated in class AB, where each of the output devices is biased slightly on all the time. This technique virtually eliminates crossover distortion.
How does rectification take place?
Type your answer her rectification takes place due to diode in rectifiers in a hwr only one diode presents it conducts during positive half and give dc out put. in fwr four (or) two diodes will presents based on type but the give both half cycles output ANSWER: A diode will pass an AC voltage trough only one way and refuse to pass the the other half of the AC signal. With just one diode the output will be the AC voltage minus the .7 v drop by the diode this output is called pulsating DC since it has no other component from the AC components in its output. It does no matter which side is rectified the + or the - the result will be either + or - pulsating DC.
Why cannot aperiodic signal be represented using fourier series?
An aperiodic signal cannot be represented using fourier series because the definition of fourier series is the summation of one or more (possibly infinite) sine wave to represent a periodicsignal. Since an aperiodic signal is not periodic, the fourier series does not apply to it. You can come close, and you can even make the summation mostly indistinguishable from the aperiodic signal, but the math does not work.
What type of signal at the NPN output?
A: It always a voltage since it is a voltage amplifier
Where does Lincs FM broadcast from?
The station Lincs FM broadcasts from a UK independent local radio station. The station serves Lincolnshire and Newark and has been broadcasting since 1992.
Why do you feedback?
A: Follow this the amplifier has infinite gain. So any input will slew it to either power supply buss as saturated. Now take this saturated signal and feed it back to the input since the feedback is negative in nature to the input it will force the output to reverts to the other buss voltage. But the since negative feedback is a proportion of the output signal it will reach a point where it is stabilized and linear. That is the intention of negative feedback feed back some output signal to stabilize to a happy stability or linear with reduced feedback of course
What is phase in current?
Phase applies only to AC current and not DC current. Reactive components - inductors and capacitors - in a system will result in the system output either lagging or leading (capacitance lags and inductance leads). If we apply an AC signal to the input of a system, we can observe the input and the output on an oscilloscope. If the system lags then the output signal will appear to be shifted to the right relative to the input singal, and vice versa for a system that leads. Since AC signals are periodic we think of one period as being 360 degrees (or 2*pi radians). The phase of output signal relative to the input signal is thus measured in degrees. For example: An AC signal of period of 10 seconds and a peak current of 2A is applied to the input of a system. The output is measured and it is found that the output current peaks 3 seconds after the input voltage - so the output lags the input, meaning the circuit has a capacitive reactance. What is the phase of the output relative to the input? Since T=10 and the phase difference in seconds is 3 the solution is simple: 360 / 10 * 3 = 108 degrees So; the output lags the input with a phase difference of 108 degrees.
What is in phase?
Phase applies only to AC current and not DC current. Reactive components - inductors and capacitors - in a system will result in the system output either lagging or leading (capacitance lags and inductance leads). If we apply an AC signal to the input of a system, we can observe the input and the output on an oscilloscope. If the system lags then the output signal will appear to be shifted to the right relative to the input singal, and vice versa for a system that leads. Since AC signals are periodic we think of one period as being 360 degrees (or 2*pi radians). The phase of output signal relative to the input signal is thus measured in degrees. For example: An AC signal of period of 10 seconds and a peak current of 2A is applied to the input of a system. The output is measured and it is found that the output current peaks 3 seconds after the input voltage - so the output lags the input, meaning the circuit has a capacitive reactance. What is the phase of the output relative to the input? Since T=10 and the phase difference in seconds is 3 the solution is simple: 360 / 10 * 3 = 108 degrees So; the output lags the input with a phase difference of 108 degrees.
How the envelope detector converts a 455 khz am signal to the message signal?
The diode flips the entire signal to the positive region like a rectifier. Then the parallel rc combination is kept charged or discharged by the carrier frequency, 455kHz. Since the Signal sits on top of the carrier, the output is the original sent signal with some ripple distortion, this can be taken care of with a simple lowpass rc filter
How long has wxpn 88.5 been around?
In 1957, WXPN first became an FM radio station at 88.9. It had been an AM station since 1945. In 1986, XPN began the process of moving their frequency from 88.9 to 88.5 to increase signal coverage.
Why to short circuit capacitor in small signal analysis of BJT?
if the input signal passes through the biasing resistors, the biasing conditions get altered . To prevent this, the input signal should be directly sent to the amplifier (BJT) .Since a capacitor acts as a short circuit for ac signals,capacitors are placed both in the input side and the output side.
Are speakers an input device?
Speakers are considered to be an OUTPUT device, as the signal is traveling out of your device, and into the speaker.
Is a microphone a input device?
Yes a microphone is an input device. Input/output devices are determined by the direction of the signal being transfered. If the signal is being sent to the Case (main part of the computer that does all the work) then the device is classified as an input device and vice versa. Since the signal from the microphone is sent to the Case, the microphone is "inputting" information into the computer.
Is headphones a input device or a output device?
If they are for hearing then its output device as they are not putting anything in to the computer, if they have a microphone attached as well then they are input/output (i.e. microphone is input, speakers are output)
What is the role of an IF amplifier together with an AGC circuit?
The radio signal at the aerial is a few micro volts. At the loudspeaker the signal will be a few volts or tens of volts. So we have to have a lot of amplification between the aerial and the output. Once the signal has been tuned in, it is quite convenient to then perform most of the amplification needed at one radio frequency - typically a little below 500 kHz. So after the tuning processes, you will have a couple of stages of IF, followed by an audio detector, and some audio amplification. [Intermediate Frequency - a frequency between that of the radio station, and the audio waves we really want.] However, the signal from the station is not perfectly steady - it fades in and out in level - particularly if the station is distant, or if the travel path is changing. The AGC [Automatic Gain Control] is designed to even out these variations in signal strength. It does this by rectifying part of the signal to DC, after the IF stages, and feeding this DC back as a bias to lower the amplification of the IF stages. Since it can only lower the amplification of the IF stages, it follows that the IF's must have more gain available than needed, so as to enable the AGC to have something to act on. This is why they must have so much gain available in the first place.
