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it is one of the configuration of BJT ,which is achieved by making the BASE grounded(i.e common base).Here the emmiter serves as the input and collector as the output.
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A PNP transistor is connected in a circuit so that the collector-base junction remains reverse biased and the emitter-base junction is forward biased This transistor can be used as a power amplifi?
No freaking way but it would make an excellent low level switch if forced at beta of 10
What is reason of invertong output of common emitter amplifier?
The output of the common emitter amplifier is inverted because increasing the base-emitter current causes a proportional increase in collector-emitter current. That increase in collector-emitter current pulls the collector towards the emitter, so the voltage on the collector will go down when the biased base voltage goes up, and vice versa. This is the characteristic of the Class A Common Emitter amplifier. Responding to a request for more details... This is for the NPN transistor. It applies to the PNP transistor as well, but directionality of voltage and current increases is reversed in that case. Start with the base-emitter circuit. You have some kind of bias network holding the base at a certain voltage. That voltage represents a certain current, which goes through the base-emitter junction and emitter resistor, if there is one. Typically, you consider that the emitter voltage is less than the base voltage by the amount of one diode junction, or about 0.7 volts. If you were to increase the input voltage, you would cause a corresponding increase in base-emitter current. The transistor has gain, beta-dc or hFe, which is basically the ratio of collector-emitter current over base-emitter current, so the base-emitter current is controlling a larger collector-emitter current. Now, focus on the collector-emitter circuit. You have some kind of resistor in the collector, and you might have some kind of resistor in the emitter. (More on the emitter resistor later.) Think of this circuit as three resistors in series, the collector resistor, the equivalent resistance of the collector-emitter junctions, and the emitter resistor. This also represents a current, one that is being controlled by the base-emitter resistance. Note that the base-emitter current is being added to the collector-emitter current, so the emitter current, by Kirchoff's current law, is the sum of the base and collector currents. Since the gain is relatively high, however, the contribution from the base is generally negligible. (In high power transistor amplifiers, gain is usually low, so base current is not negligible, so we do take it into account.) The crucial factor here is that the collector current is proportional to the base current, in the ratio of beta-dc, or hFe. If, for instance, base current were increased by 1 ma, with an hFe of 200, then the collector current would increase by 200 ma. Well, sort of.... You have to consider the transistor's limits, and you have to consider whether or not you are opereating in linear mode. Limits are easy, just check the specs. Lets look at linear mode... If you attempt to pull more collector current than the collector-emitter circuit would allow, i.e. to make the equivalant collector-emitter resistance go to zero, then the transistor starts operating in saturated mode. In saturated mode, the transistor is acting as a switch, and it is distinctly non-linear. Even if not saturated, the transistor can be poorly linear when operating at the ends of the linear range. This is why any good design includes consideration of linear mode range. You want to operate in the center of the linear range, which simply means that we bias the base to cause the collector to be in the middle of its optimal range, giving maximum linearity. Summarizing so far, we have a transistor that is multiplying its base current by some factor, beta-dc or hFe, causing a proportional collector current. With this viewpoint, the amplifier is non-inverting because increasing base current causes collector current to increase. We call the circuit inverting, however, because we want to think of the collector voltage rather than the collector current. Remember that the transistor has an equivalent resistance. In particular, the collector-emitter resistance changes in response to stimuli on the base. In order for the collector current to increase, the equivalent resistance must decrease. Looking at the collector-emitter circuit, you have a voltage divider, collector resistance at the top, and the sum of equivalent collector-emitter resistance and the emitter resistance at the bottom. It is easy to see that, if the collector current increases, the collector voltage must decrease. That is why we call this an inverting amplifer. Back to the emitter resistor... When we say "common emitter", we mean that the emitter is common and we analyze everything else. You can design and operate this amplifer with no emitter resistor, and that would be a true common (or grounded) emitter configuration. Problem is the circuit will not be stable... First, gain varies amongst transistors, even amongst transistors of identical design. It is common to state that hFe ranges from 80 to 400, as an example. The circuit design must consider this variability. If you want predictable and stable gain, you must compensate for gain variation. You design the circuit for minimum hFe, but you look at what happens with maximum hFe. To make matters worse, the junction voltage at any particular current varies with temperature, sometimes substantially. This means that your beautifully designed circuit is unpredictable when it gets warm, and all circuits that manipulate power, even small amounts of power, get warm. Its all a matter of degree. There are many ways to compensate for gain variations. One of them is to use an emitter resistor. This effectively places a limit on gain by moving the primary factor for gain from the transistor to the circuit. The gain of a common emitter amplifier is hFe. When there is an emitter resistor, however, the gain is collector resistance divided by emitter resistance. If that ratio is less than hFe, then hFe variability will not affect gain.
What is the best way to describe the function of a typical transistor in an electronic circuit?
A transistor in a circuit can do many things. It can be used to amplify voltage signals, or current signals, create current and voltage sources, make buffers, and so on. Transistors also find a major use in logic circuits (ie, where signals can either be a '0' or a '1'), where they essentially act as a switch, and can be used to create inverters, AND gates, OR gates, and all sorts of useful components. By itself, a transistor is a three-terminal device that can control the current going through two of its terminals through the voltage applied at the third terminal. But there are many applications for a transistor in its many different configurations, which is why it is so important in modern electronic technology.
Which is better as a switch diode or transistor?
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.
How does a transistor make a signal bigger?
by injecting a small current into the base a larger proportional current will flow in the collector by adding a resistor into the path a big voltage drop will be evident therefore voltage amplification
A PNP transistor is connected in a circuit so that the collector-base junction remains reverse biased and the emitter-base junction is forward biased This transistor can be used as a power amplifi?
No freaking way but it would make an excellent low level switch if forced at beta of 10
I am trying to make a seat belt safety light How do you add in a buzzer to an astable circuit which already has and LED?
Use the astable to switch a power transistor and connect the buzzer as the transistor load.
Can you make a transistor by connecting two diodes back to back?
Two diodes, whether or not discreet, cannot work together as a transistor. The diodes and transistor have different profiles to optimize them for their specific functions
What is a transistor composed of?
SILICON or common sand with doping of the right ratio to make a transistor. three layers of semiconductor material
Why two diode join cant act as transistor?
No, it is not possible because in transistor the depletion layers formed in Emitter-Base Junction & Collector-Base Junction are penetrable by both current carriers but in this case of two diodes; the formed depletion region are not penetrable for current carriers (hole &electron). Also, a transistor works only because the base layer is very thin. You won't get that thin layer between emitter and collector just by connecting two diodes together. This thin base layer places the Emitter and Collector in very close proximity to each other. This allows majority carriers from the emitter to diffuse as minority carriers through the base into the depletion region of the base-collector junction, where the strong electric field collects them. In other words the emitter/base current flow draws some of the barrier charge away from the collector/base junction and allows collector/emitter current to flow across the base using minority carriers. So transistor action is not possible. But we can make transistor by connecting two diodes and two dependent current sources i.e. Ebers-Moll model of transistor. This is true only when you want to make the transistor act like a on/off switch, but you cannot make this setup of diodes to act like an amplifier. Whereas the transistor also acts as an amplifier too A transistor can act as: (1) on/off switch (2) amplifier. Diode is made up of two layers and one junction. Transistor is made up of three layers and two junctions.
You have bel 187 transistor to same transistor?
This question does not make sense.
Why common emitter configuration is mostly used for transistor as switch?
because in ce configuration value of input voltage requried to make the transistor on is very less value of the output voltage or output current
How do you test Resistance Capacitance diodes and transistors on cathode ray oscilloscope?
It is always better to remove a component from the circuit for proper testing but most of the time a resistor can be tested with a DMM set to the appropriate ohm scale, the same with a diode where the DMM is set to diode setting. A transistor is more complicated, you first have to find the base connector and with your DMM set to diode, NPN Transistor, with negative probe to the base and positive to emitter or collector the smallest reading will be the collector and the slightly higher reading will be the emitter, no reading mean that it can be a PNP transistor then you will need to swap your probes, still no reading or a very low reading will mean the transistor is damaged In actuality tektronics do make a curve tracer oscilloscope to test active components . But the speed is very limited. So while it may tell you that the part is good or bad it will not tell you how good or how bad it will function in the actual circuit
Did someone ask the question can you use a transistor as a diode there is a device called a transistor diode connect base to either c or e forgot which to make a zero bias diode?
You can use a transistor as a diode if you connect the base to the collector. Any forward current through the base-emitter junction would cause a corresponding increase in the available current through the collector-emitter junction. Since the base-emitter and collector-emitter junctions are in parallel, this would effectively be a diode, but a true diode would be a better solution if diode functionality is what seek. A: There are actually two diodes, per se, inside a transistor. The base to emitter diode will suffice. By tying the collector to the base it will in effect be two diodes in parallel.
Is a transistor a diode?
No.Di, or bi, means two. A diode, from the Greek di (two), and ode (path), has, rather obviously, two connections, which, in older ones (valves/thermionic diodes), were called electrodes.A transistor has three connections (so it would make, at least grammatic, sense to call it a triode).
Can you replace a npn transistor by a pnp transistor?
Think of it this way: "P" is for Positive and "N" is for Negative So basically put a PNP Transistor Would use N to Switch P, in the name "PNP" or "NPN" the first character is for the polarity of the Collector-pin, the second for the Base-Pin, and the third for the Emmiter-pin. If you have a NPN Transistor you can`t just replace it with an PNP as the polarities differ. If you can find a way to change those polarities then sure it could work. I would say it`s best go out and buy a few of both so you have a few, otherwise if the application of the transistor is not in a high-current or high-voltage circuit try and find another circuit with the required type of transistor. Absolutely most transistors can be replaced with other similar transistors. Different transistors have different conditions they work by so you should do some research and replace it with another that is either the same or have approximately the same data. Example 1: A burned transistor with the data NPN, 45Volt, 100mA, 0,3Watt, need to be replaced. It is a discontinued transistor, so unfortunately no original spare part can be found. Check the max voltage of the circuit where it was. If the voltage is close to 35 volt, then you may want to replace it with a higher voltage transistor. If it is lower, say max 20 Volt, then you should be able to replace it with a lower voltage transistor. Check the type of circuit where it was. If in an audio amplifier, then you should choose a 'low noise' audio transistor. Look at the NPN transistors you can get hold of and make your choice based on similar or more current, similar or more wattage, similar or lower or even higher voltage. Most small signal transistors are interchangeable if you follow these steps. Even most power transistors are interchangeable but you should make an extra effort and check/match the HFE Data on the transistor too. Normally no need for an exact match at all.
What is reason of invertong output of common emitter amplifier?
The output of the common emitter amplifier is inverted because increasing the base-emitter current causes a proportional increase in collector-emitter current. That increase in collector-emitter current pulls the collector towards the emitter, so the voltage on the collector will go down when the biased base voltage goes up, and vice versa. This is the characteristic of the Class A Common Emitter amplifier. Responding to a request for more details... This is for the NPN transistor. It applies to the PNP transistor as well, but directionality of voltage and current increases is reversed in that case. Start with the base-emitter circuit. You have some kind of bias network holding the base at a certain voltage. That voltage represents a certain current, which goes through the base-emitter junction and emitter resistor, if there is one. Typically, you consider that the emitter voltage is less than the base voltage by the amount of one diode junction, or about 0.7 volts. If you were to increase the input voltage, you would cause a corresponding increase in base-emitter current. The transistor has gain, beta-dc or hFe, which is basically the ratio of collector-emitter current over base-emitter current, so the base-emitter current is controlling a larger collector-emitter current. Now, focus on the collector-emitter circuit. You have some kind of resistor in the collector, and you might have some kind of resistor in the emitter. (More on the emitter resistor later.) Think of this circuit as three resistors in series, the collector resistor, the equivalent resistance of the collector-emitter junctions, and the emitter resistor. This also represents a current, one that is being controlled by the base-emitter resistance. Note that the base-emitter current is being added to the collector-emitter current, so the emitter current, by Kirchoff's current law, is the sum of the base and collector currents. Since the gain is relatively high, however, the contribution from the base is generally negligible. (In high power transistor amplifiers, gain is usually low, so base current is not negligible, so we do take it into account.) The crucial factor here is that the collector current is proportional to the base current, in the ratio of beta-dc, or hFe. If, for instance, base current were increased by 1 ma, with an hFe of 200, then the collector current would increase by 200 ma. Well, sort of.... You have to consider the transistor's limits, and you have to consider whether or not you are opereating in linear mode. Limits are easy, just check the specs. Lets look at linear mode... If you attempt to pull more collector current than the collector-emitter circuit would allow, i.e. to make the equivalant collector-emitter resistance go to zero, then the transistor starts operating in saturated mode. In saturated mode, the transistor is acting as a switch, and it is distinctly non-linear. Even if not saturated, the transistor can be poorly linear when operating at the ends of the linear range. This is why any good design includes consideration of linear mode range. You want to operate in the center of the linear range, which simply means that we bias the base to cause the collector to be in the middle of its optimal range, giving maximum linearity. Summarizing so far, we have a transistor that is multiplying its base current by some factor, beta-dc or hFe, causing a proportional collector current. With this viewpoint, the amplifier is non-inverting because increasing base current causes collector current to increase. We call the circuit inverting, however, because we want to think of the collector voltage rather than the collector current. Remember that the transistor has an equivalent resistance. In particular, the collector-emitter resistance changes in response to stimuli on the base. In order for the collector current to increase, the equivalent resistance must decrease. Looking at the collector-emitter circuit, you have a voltage divider, collector resistance at the top, and the sum of equivalent collector-emitter resistance and the emitter resistance at the bottom. It is easy to see that, if the collector current increases, the collector voltage must decrease. That is why we call this an inverting amplifer. Back to the emitter resistor... When we say "common emitter", we mean that the emitter is common and we analyze everything else. You can design and operate this amplifer with no emitter resistor, and that would be a true common (or grounded) emitter configuration. Problem is the circuit will not be stable... First, gain varies amongst transistors, even amongst transistors of identical design. It is common to state that hFe ranges from 80 to 400, as an example. The circuit design must consider this variability. If you want predictable and stable gain, you must compensate for gain variation. You design the circuit for minimum hFe, but you look at what happens with maximum hFe. To make matters worse, the junction voltage at any particular current varies with temperature, sometimes substantially. This means that your beautifully designed circuit is unpredictable when it gets warm, and all circuits that manipulate power, even small amounts of power, get warm. Its all a matter of degree. There are many ways to compensate for gain variations. One of them is to use an emitter resistor. This effectively places a limit on gain by moving the primary factor for gain from the transistor to the circuit. The gain of a common emitter amplifier is hFe. When there is an emitter resistor, however, the gain is collector resistance divided by emitter resistance. If that ratio is less than hFe, then hFe variability will not affect gain.
