How does a transistor act as a oscillator amplifier and switch?
The red line goes down and the blue line just goes all the way up. Cool right?
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Amplifiers are circuits which transfer an input signal into anoutput signal. Oscillators are autonomous circuits powered by a constant energysource. Oscillators produce a steady state signal e.g. a square wavesignal, a sinusoidal signal or a chaotic signal. Real world oscillators are non linear cir…cuits. Linear oscillators are mathematical fiction (a complex pole paircan not balance on the imaginary axis). Clarification. Yes, while most oscillators *do*use amplifiers with output-to-input feedback. there are some thatdo not. The classic example is the now-obsolete point-contact transistorthat exhibited a negative resistance, and couldtherefore oscillate with a two-terminal tuned circuit and nofeedback. The tunnel diode, now also obsolete, also exhibitsnegative resistance. Another example is the neon lamp "relaxation" oscillator thatrelies on a resistor-capacitor circuit's charge/discharge time.This design was also used in early oscilloscope time-bases. TheUni-junction transistor operates similarly. Disagreements: (i) "Linear oscillators aremathematical fiction". If so, what of (for example) the Wein Bridgeoscillator that uses feedback to stabilise its operating point.(ii) Oscillators may be designed to produce an intermittent ("squegging") signal, as used in somelifeboat/search and rescue transmitters, or the super-regenerativereceiver. The (very) basic answer is that an oscillator is an amplifier witha positive feedback path engineered into. This sets up a situationwhere the feedback returns a bit of the output signal to the inputof the stage to "keep it going" and to permit it to sustain the"continuous" output of a (frequency controlled) signal. All amplifiers can be made to oscillate, and all oscillatorsamplify. The difference is in how we set them up, which we will doin accordance with what we want out of them. Clarification: Note that the loop gain must begreater than one for tuned-circuit oscillators. An emitter-follower(with a gain less than 1.0) can be made to oscillate onlyif the tuned circuit has a voltage gain ("step-up"). To understand the differences it is helpful to look at thesimilarities. They both need some form of amplifier to work. The "goodness" of an amplifier is specified by the amount of gain(among other things) it possesses i.e. by how much it amplifieswhich is measured by seeing how much bigger the output is comparedwith the input. All circuits contain feedback paths where part of the output signalfinds its way back to the input - some intentional (as in anoscillator) and some unwanted (as in an amplifier). If we start with an ordinary amplifier circuit and graduallyincrease the gain of the amplifying bit we will eventually get tothe point where the specific combination of that amount of gain andthe characteristics of the feedback path result in enough energytravelling through the feedback path to cause the amplifier tobecome unstable. In other words it oscillates! The frequency of oscillation is largely determined by thecharacteristics of the feedback path and when the feedback signalis big enough and is in phase with the original input signal itoscillates. (MORE)
we know that in a transistor we have three types of regions: EMITTER, COLLECTOR, BASE, and we know that emitter is highly doped, so charge carriers are very high, so resistance is very less, and on the other side collector is moderately doped so charge carriers are less, so resistance is very high. …So from the above concept we conclude that in a transistor current is flowing from low resistance to high resistance. for example the 100 electrons are moving from emitter to base, in base only some (4 electrons) of the electrons are neutralized, and remaining 96 electrons are moved to collector terminal through high resistance path. so now same current flowing through high resistance so voltage amplified. (MORE)
When used as a switch, a transistor is usually driven completely on (saturation) or completely off (cutoff). There are a few kinds of switching circuits though (e.g. ECL) that avoid saturation/cutoff to obtain faster speed, these operate on a fixed constant current and switch it through one of two t…ransistors. When used as an amplifier it is biased so that it operates in a linear, or near-linear, part of its characteristic curve so that the output faithfully copies the input. (MORE)
It amplifies current and voltage from other transistors and outputs go to inputs respectively and the gain increases and eventually to the speaker output, or whatever its used for.
When we use a transistor as a switch, we will be operating it in either an "all on" or an "all off" mode. Depending on the transistor, we'll just apply some "maximum" base voltage to drive it into saturation and allow for maximum collector current, or we'll not apply any base voltage and the device …will not be conducting any current through it. That's the "on and off" of it.This idea applies to the "standard" transistor. Things change a bit for FETs and some other devices, but the concept of using the device in an "all on" or "all off" state is common to the application of all devices acting as switches. We either turn them "all the way on" or "all the way off" via the base, gate or applicable terminal of the device. (MORE)
ALL transistors can be used as switch. however there are certain parameters to be noted. speed saturation and storage time. Once a transistor is saturated current may flow either way
when the imput signal is so much that is oscillates the speaker, all an oscillator is defined as a device with A.C. feedback.
An amplifier can become and oscillator by adding positive feedback from the output back to the input. Positive feedback means that the phase of the signal fed back to the input is the same as the phase of the output signal. In the case of a high frequency oscillator, a tuned circuit (inductor and ca…pacitor) or a quartz crystal in the input circuit will determine the frequency of oscillation.. (MORE)
A transistor is an electronic component. By itself it has littleuse. An amplifier is a complete, functional circuit, generally madeup of several components. A transistor can be a component part ofan amplifier, however an amplifier may be constructed without anytransistors (using vacuum tubes instead…, for instance). (MORE)
The amplifier projects the audio signal into something we can comprehend. The oscillator creates a fixed or variable pitch, which is fed to the amplifier. Amplifiers are circuits which transfer an input signal into an output signal. Oscillators are autonomous circuits powered by a constant ene…rgy source. They produce a steady state signal e.g. a sinusoidal signal or a chaotic signal. (MORE)
A transistor acts like a valve or gate that opens and closes, and allows a current to flow. Since the amount of current that flows is controlled by another input, they can be used to make amplifiers. Carbon microphones and vacuum tubes have the same property, and so have also been used to make ampli…fiers historically. (MORE)
A: When a transistor is saturated current can flow in both direction qualifying it as a switch
A transistor is often referred to as an oscillator because of itsability to transfer resistance. it can also switch off and onrepeatedly, mimicking an oscillator.
A transistor has three sections, an emitter, base, and collector. By extracting a small number of electrons from the base, a large # of electrons can flow across the transistor from the emitter, thru the circuit, and back to the collector.
An amplifier is usually stabilized by means of negative feedback. An oscillator is an amplifier which is made unstable by means of positive feedback.
by saturating the junctions it becomes a low resistance current path from a relatively hi impedance.
Yes, transistors can be used as amplifiers, but they are not limited to only this use (they are also used in logic circuits, for example).
depends on the circuit it is used in: . CE/CS is inverting voltage amplifier . CC/CD is noninverting current amplifier . CB/CG is noninverting voltage amplifier
oscillator needs positive feedback in order to produce the undamped oscillations .This is done with help of he amplifier circuit.The oscillations are produced by the tank circuit cosisting of inductor and capacitor.The output of this tank circuit is fedback to the transistor which amplifies it and g…ive back to the tank circuit input.If the gain of the circuit consisting of tank circuit and amplifier is more than one and the feedback given to tank circuit is in phase then we get undamped scillations as the output. (MORE)
A transistor used as a switch is operated in saturated mode, where the ratio of base-emitter current over collector-emitter current is far more than hFe, or beta gain. The transistor is either fully on or fully off in this mode. A transistor used as an amplifier is operated in linear mode, where …the ratio of base-emitter current over collector-emitter current is equal to or less than hFe, or beta gain. The transistor is partially on in this mode, and is operating as a current controlled current sink. (MORE)
Explain the operation npn transistor when used as amplifier.. and explain the basic operation of NPN when used as switch?
The NPN transistor when used as an amplifier is operating in linear mode, and, when operating as a switch, in saturated mode. In the following discussion, base currrent means base-emitter current, while the base is more positive than the emitter, and collector current means collector-emitter curr…ent, while the collector is more positive than the emitter. There is base-collector current, but we are going to ignore it for now - besides, we are going to discuss class A, common emitter, configuration. The PNP transistor is very similar. Everything is backwards, including Vcc, which is now -Vcc, or appropriate reconfiguration. The rules are the same - just backward. In switched or saturated mode, the ratio of base to collector current is far greater than beta-dc, or hFe, so the transistor is operating way out of its linear mode. We call that saturated mode, and the transistor is essentially either fully on or fully off, and therefore operating as an on-off switch. The rest of this discussion will focus on linear or amplilfier mode. If the ratio of base to collector current is less than beta-dc, or hFe and, if both base and collector voltage are greater than cutoff voltage, then the transistor is operating in linear mode. Well, sort of, for best linear mode, we look at the data sheet, or make empirical observations, and we pick the base and collector currents that are centered between the base knee and the collector knee, i.e. "in the middle of" the linear region. In this mode, a very small base current can control a much larger collector current, and, most importantly, a very small change in base current can create a much larger change in collector current. In the theoretical case, for example, where the emitter is grounded and where hFe is 100, then 1 mA of base current translates to 100 mA of collector current, and 2 mA of base current translates to 200 mA of collector current. Problem is, that hFe varies amongst even so called identical transistors, and hFe varies as a function of temperature as well. So, in the practical case, an emitter resistor is added to stabilize the transistor and place limits on the need for hFe of a particular value. Done properly, this will yield predictable gain for various transistors and for various temperatures. Now, lets look at how gain works in the practical sense. The base voltage is also a known delta above emitter voltage. Yes, temperature will affect this, but proper design can make this a negligable factor. The emitter current times the emitter voltage results in a known voltage. By Norton's current law, the base current and the collector current add up to be the emitter current, but by hFe, the base current is very much smaller than collector current, meaning that the really important part is that collector and emitter current are the same for all practical purposes. So, now add a collector resistor. Ignoring base current, the collector/emitter circuit is a series circuit, and Norton's current law, reinterpreted for series circuits, says the two resistors have the same current. Think about what that means; if the current in both resistors is the same, then the ratio of the voltage across the two resistors is proportional to their value. The gain of the amplifier is collector resistor divided by emitter resistor. That is critical knowledge. Again, base current enters into the equation but, if hFe is high enough, it does not matter. All that is left, then, is to bias the base. You want to pick a base voltage (current) that places the collector current in the center (or in an appropriate point) of the linear region. Choose a nominal hFe, divide by collector current, and you get an approximation of what base current bias should be. Choose a resistor divider to match, keeping in mind that the two resistors (base to Vcc and base to Gnd) in parallel will reflect your effective input impedance. Review everything, particularly your power levels. To calculate the power through the collector/emitter junction subtract collector resistor voltage from emitter resistor voltage from Vcc, and you get collector/emitter voltage. Multiply that by collector current, and you get power dissipated by the transistor in nomial bias condition. Play with the values until you have what you want. You could even set this up in a spreadsheet. Last, but not least, there is a base bias voltage. If you are going to amplify something, you need to maintain that nominal bias voltage. Connect a series capacitor between the base and the input point and you will be able to operate from an AC signal that is zero referenced. Just pick the RC time constant appropropriate for your application. Similarly, there is a collector bias, so, if you want an AC output zero referenced, use a series capacitor also in between the collector and the ouput. This is an AC coupled, inverting amplifier. There are DC coupled non-inverting versions, but they are more complicated, requiring more than one transistor, and this answer does not address them. Good luck! (MORE)
A: actually any active components will oscillate with positive feedback A transistor can be used as an amplifier along with an LC tank circuit to form an oscillator; it is an active device (as LIBURNO states) which will amplify the feedback signal coming out of the LC tank circuit. The tank circuit… has a natural resonant frequency, meaning the L and C together will try to generate a specific frequency; this is then fed back into the input of the transistor amplifier, and the output is fed to the LC tank circuit exacerbating this oscillation until it reaches its' maximum level. An inverting amplifier can be used similarly; the output is fed to the input; this will cause the output to change as fast as the amplifier can. The frequency of this design is much harder to control, but potentially higher. Also, without the LC tank, the output voltage will remain lower. (MORE)
A: Very easy to do just provide a positive feedback and/or a phase shift it will oscillate
amplifier is electronic circuit which is used to increase the amplitude of the input signal without affecting its frequency and phase.
An amplifier is any device that changes, usually increases, the amplitude of a signal. while a transistor is a semiconductor device used to amplify and switch electronic signals. Hope this helps
When you turn it on, it conducts, when you turn it off it doesn't conduct. Just like a switch.
the magical computer fairies wave there magic wands and make electricity appear sometimes they live in transistors as this is where theyare happiest and that happiness is turned into electricity
A: The small base current will control the collector current flow by adding a resistor this changes of current flow will be evident as a voltage amplifier.
A transistor can act as an amplifier. An amplifier you use for music might have many transistors as well as many other types of components. Transistors have other applications as well.
An oscillator will generate a waveform. An amplifier takes a small wave and 'amplifies' it to a big wave.
A transistor does not act as an amplifier. It is used as a component in an amplifier circuit.
the electrical signal coming out from the micro phone is very low &this cannot drives the loud speaker.For this purpose we incresing the signal level which is coming out from the microphone (usually an Ac signal)is known as amplifier.it cannot incresing this signal level without using external energ…y(as per law of conservation of energy rule)For this we use external dc energy.only the device which can convert the external dc energy into ac energy is transistor. so we say transistor as an amplifier (MORE)
Yes, but only if you already have the stronger current. A transistor is basically a switch which is activated by an electric current. AC (Alternating Current) can be amplified by using it to "switch" the transistor on and off, while applying DC (Direct Current) to the transistor. DC could be amplifi…ed as well, but you need a stronger current which will be switched off going into the transistor. (MORE)
When transformer is used in step up mode then we can use transformer as amplifire
In forward active mode, transistor can amplify current and/or voltage signals. So here, it can be used as an amplifier. To understand this read as follows... There are four mode of operations for a transisitor. 1. Forward active mode. 2. Reverse active mode. 3. Cut Off mode. 4. Saturat…ion Mode. To understand the modes, lets consider a pnp/npn transistor. In forward active mode, Emitter-Base Junction is forward biased & Collectror-Base Junction is reverse Biased. In Reverse active mode, Emitter-Base Junction is reverse biased & Collector Base junction is forward biased. In Cut off mode, both the junctions are reverse biased. In Satuiration mode, both the junctions are forward biased. (MORE)
The question should be like: How can a transistor be used as an amplifier...?? Answer: There are four mode of operations for a transisitor. 1. Forward active mode. 2. Reverse active mode. 3. Cut Off mode. 4. Saturation Mode. To be an amplifier, transistor must be used in forward activ…e mode. To understand the modes, lets consider a pnp/npn transistor. In forward active mode, Emitter-Base Junction is forward biased & Collectror-Base Junction is reverse Biased. In Reverse active mode, Emitter-Base Junction is reverse biased & Collector Base junction is forward biased. In Cut off mode, both the junctions are reverse biased. In Satuiration mode, both the junctions are forward biased. (MORE)
A transistor can be used as an amplifier because the electrons in the base are multiplied by a gain factor to give the collector current.
Depends on the type of amplifier. There are a lot of different circuits of amplifiers and each one of them use proper transistors, that works better for that circuit. Moreover, on every stage of the amplifier are used different transistors as well.
Transistors, at least the typical bi-junction transistor, actually amplify current. We set them up in a voltage divider circuit that converts current gain into voltage gain. The simple explanation is that a small delta current on base-emitter causes a larger delta current on collector-emitter. Th…e gain is either hFe or collector resistance divided by emitter resistance, whichever is less. (MORE)
Amplification is the process of linearly increasing the amplitude of an electrical signal. - A transistor can act as an amplifier directly using the gain, b. - Keep in mind that when a transistor is biased in the active (linear) region, the BE junction has a low resistance due to forward bias and th…e BC junction has a high resistance due to reverse bias. i) DC and AC quantities - Amplifier circuits have both ac and dc quantities. - Capital letters are used will be used for both ac and dc currents. - Subscript will be capital for dc quantities. - Subscript will be lowercase for ac quantities. ii) Transistor amplification - A transistor amplifies current because the collector current is equal to the base current multiplied by the current gain, b. - Base current (I B ) is small compared to I C and I E . - Thus, I C is almost equal to I E . (MORE)
There are three pins on a transistor. One is hooked to the input signal. One to the power supply, and the third to ground. (These have different names depending on whether the particular device in your hand is a bipolar transistor or a field-effect transistor.) The pin hooked to the input signal con…trols the amount of voltage allowed to pass from the power supply pin to the ground pin. So, basically, to amplify an input signal you feed more power into the "power supply" pin on the transistor than you are feeding into the "input" pin. You don't want a huge amount of difference between the input and output on a transistor because it'll distort if you ask it for much, so a really high-powered transistor amp has multiple stages. That's one large difference between designing a transistor amp and a tube amp: a tube will give you a lot more amplification in one stage before it distorts. Prime example: the Marshall 2203 amplifier head, which is the most popular heavy-metal guitar amp head around. It's a 100-watt amplifier that contains one stage of preamplification with two tubes and one power amplification stage with four tubes. If that was a transistor amp it'd have at least 50 transistors in it. Another example, and a better one at that, is the 4CX35000 radio tube...which will amplify a 1750-watt input to 35,000 watts in one stage. I love solid state devices for their low power consumption, reliability and low heat, but if you're looking for a lot of gain in very few devices, tubes have always been the way to go. (MORE)
A transistor is a device that controls a large current with a small current. If it has an Hfe parameter of 50, then a 1 mA AC input current to it's base will cause a 50 mA AC current component at it's collector.
transistor is a nonlinear device. it will acts as a swicth based on the cut in voltage we can easily identifying the the transistor is in forward or reverse bias.in forward it is 'on' reverse bias 'off'.
"Transistor" name itself revels it transfers resistance from its input to its output (Transfer of resistance). Input resistance varies when input voltage varies, similarly output resistance varies and this leads to voltage variation at the output. Thus input to output voltage variation is called amp…lification. this is how transistor can be used as an amplifier. If input voltage is minimum output voltage becomes maximum i.e. its output resistance becomes maximum in common emitter configuration. Thus if no voltage is applied at the input its collector resistance becomes infinite or as if open circuit. Similarly if input current is increased output current increases and out put can behave as short circuit. This is how output current can be switched off or on using no input current or with minute input current. Unlike a digital device, the transistor is an analogue device which can be switch on/off to maximum or any gradient in between. Providing a small AC voltage to the base creates an amplified analogue of this signal across the emitter and collector. (MORE)
for amplify we use common collector biasing and take high input resistance and low output resistance
All transistors are reactive to light. If you cut the top off of a regular PNP or NPN transistor and expose it to a sufficient amount of light, a current will conduct through any two of its leads. If you want to use it as a switch that turns on when it's night, you could attach the output to an inve…rter and then put the transistor up against a window. I guess when it got dark, it would conduct electricity... (MORE)
In a transistor, a small current in the base-emitter circuit stimulates a significantly larger current in the collector-emitter circuit by breaking down the barrier in internal diode junctions. External resistor networks may be used to regulate these currents and produce larger voltages from smaller… ones. (MORE)
I do not understand your question, oscillators CAN be built with either (and many other amplifying components). A few examples are: . triode tube . tetrode tube . pentode tube . beam power tube . pentagrid converter tube (cathode and first 2 grids form local oscillator) . magnetron tube . … klystron tube . traveling wave tube . thyratron tube . neon lamp . point contact transistor . junction transistor . surface barrier transistor . field effect transistor . tunnel diode . unijunction transistor . silicon controlled rectifier . magnetic amplifier . FERRACTOR . operational amplifier IC . timer IC . logic inverter IC . etc. Perhaps you meant why it was in some specific circuit that you don't give any reference to. If this is the case, I cannot answer without a reference to the specific circuit. One possibility for selecting a tube instead of a transistor to implement an oscillator would be that it must deliver higher power and/or voltage than a transistor is capable of. (MORE)
That depends on both the input signal and the type of amplifier thetransistor is used in.
Only because the circuit that its embeded in is designed that way. Remember, a transistor is basicly an amplifier ... only if you design everything to go to the extreams will it act asa switch.