As our brain is made up of 100 billion of cells termed Neurons which are used to think and memorize things. Like as computer also have billions of tiny brain cells named Transistors. It is composed of chemical element extract from sand called Silicon. Transistors change the theory of electronics radically since it has been designed over half a century before by John Bardeen, Walter Brattain, and William Shockley.
So, we will tell you how they work or what they actually are?
What are Transistors?
These devices are made up of semiconductor material which is commonly used for amplification or switching purpose, it can also be used for the controlling flow of voltage and current. It is also used to amplify the input signals into the extent output signal. A transistor is usually a solid state electronic device which is made up of semiconducting materials. The electronic current circulation can be altered by the addition of electrons. This process brings voltage variations to affect proportionally many variations in output current, bringing amplification into existence. Not all but most of the electronic devices contain one or more types of transistors. Some of the transistors placed individually or else generally in integrated circuits which vary according to their state applications.
“Transistor is a three leg insect type component, which is placed singly in some devices but in computers it is packed inside in millions of numbers in small microchips”
What does a transistor made up of?
Transistor consists of three layers of semiconductor, which have an ability to hold current. The electricity conducting material such as silicon and germanium has the ability to carry electricity between conductors and insulator which was enclosed by plastic wires. Semiconducting materials are treated by some chemical procedure called doping of the semiconductor. If silicon is doped with arsenic, phosphorous & antimony, it will obtain some extra charge carriers i.e., electrons, are known as N-type or negative semiconductor whereas if silicon is doped with another impurities like as boron, gallium, aluminum, it will obtain fewer charge carriers i.e., holes, are known as a P-type or positive semiconductor.
How Does Transistor Work?
The working concept is the main part to understand how to use a transistor or how it works?, there are three terminals in the transistor:
• Base: It gives base to the transistor electrodes.
• Emitter: Charge carriers emitted by this.
• Collector: Charge carriers collected by this.
If the transistor is NPN type, we need to apply a voltage of 0.7v to trigger it and as the voltage applied to base pin the transistor turns ON which is the forward biased condition and current start flowing through the collector to emitter (also called saturation region). When the transistor is in reversed biased condition or the base pin is grounded or having no voltage on it the transistor remain in OFF condition and not allow the current flow from collector to emitter(also called cut-off region).
If the transistor is PNP type, it’s normally in ON state but not to be said perfectly on till the base pin gets perfectly grounded. After grounding base pin the transistor will be in reverse biased condition or said to be turned ON. As the supply provided to the base pin it stops conducting current from collector to emitter and the transistor said to be in OFF state or forward biased condition.
For the protection of the transistor we connect a resistance in series with it, for finding the value of that resistance we use the formula below:
RB = VBE / IB
Different Types of Transistors:
Mainly we can divide the Transistor in two categories Bipolar Junction Transistor (BJT) and Field Effect Transistor (FET). Further we can divide it like below:
Bipolar Junction Transistor (BJT)
A Bipolar junction transistor is made up of doped semiconductor with three terminals i.e., base, emitter & collector. In this procedure, holes and electrons both are involved. A large amount of current passing into collector to emitter switches up by modifying small current from base to emitter terminals. These are also called as current controlled devices. NPN and PNP are two prime parts of BJTs as we discussed earlier. BJT turned on by giving input to base because it has lowest impedance for all transistors. Amplification is also highest for all transistors.
The types of BJT are as follows:
In the NPN transistor middle region i.e., base is of p-type and the two outer regions i.e., emitter and collector are of n-type.
In forward active mode, the NPN transistor is biased. By dc source Vbb, the base to emitter junction will be forward biased. Therefore, at this junction depletion region will be reduced. The collector to base junction is reverse biased, collector to base junction depletion region will be increased. The majority charge carriers are electrons for n-type emitter. The base emitter junction is forward biased so electrons move towards base region. Therefore, this causes the emitter current Ie. The base region is thin and lightly doped by holes, electron–holes combination formed and some electrons remain in base region. This causes very small base current Ib. The base collector junction is reversed biased to holes in the base region and electrons in the collector region but it is forward biased to electrons in base region. Remaining electrons of base region attracted by collector terminal cause collector current Ic. Check more about NPN Transistor here.
2. PNP Transistor:
In the PNP transistor middle region i.e., base is of n-type and the two outer regions i.e., collector and emitter are of p-type.
As we discussed above in NPN transistor, it is also operating in active mode. The majority charge carriers are holes for p-type emitter. For these holes, the base emitter junction will be forward biased and moves towards base region. This causes the emitter current Ie. The base region is thin and lightly doped by electrons, electron–holes combination formed and some holes remain in base region. This causes very small base current Ib. The base collector junction is reversed biased to holes in base region and holes in collector region but it is forward biased to holes in base region. Remaining holes of base region attracted by collector terminal cause collector current Ic. Check more about PNP transistor here.
What are Transistor Configurations?
Generally, there are three types of configurations and their descriptions with respect to gain is as follows:
Common Base (CB) Configuration: It has no current gain but has voltage gain.
Common Collector (CC) Configuration: It has current gain but no voltage gain.
Common Emitter (CE) Configuration: It has current gain and voltage gain both.
Transistor Common Base (CB) Configuration:
In this circuit, base is placed common to both input and output. It has low input impedance (50-500 ohms). It has high output impedance (1-10 mega ohms).Voltages measured with respect to base terminals. So, input voltage and current will be Vbe & Ie and output voltage and current will be Vcb & Ic.
- Current Gain will be less than unity i.e., alpha(dc)= Ic/Ie
- Voltage gain will be high.
- Power gain will be average.
Transistor Common Emitter (CE) Configuration:
In this circuit, the emitter is placed common to both input and output. The input signal is applied between base and emitter and the output signal is applied between collector and emitter. Vbb & Vcc are the voltages. It has high input impedance i.e., (500-5000 ohms). It has low output impedance i.e., (50-500 kilo ohms).
- Current Gain will be high(98) i.e., beta(dc) =Ic/Ie
- Power gain is upto 37db.
- Output will be 180 degrees out of phase.
Transistor Common Collector Configuration:
In this circuit, collector is placed common to both input and output. This is also known as emitter follower. It has high input impedance (150-600 kilo ohms).It has low output impedance(100-1000 ohms).
- Current gain will be high(99).
- Voltage gain will be less than unity.
- Power gain will be average.
Field Effect Transistor (FET):
Field Effect Transistor contains the three regions such as a source, a gate, a drain. They are termed as voltage controlled devices as they control the level of voltage. To control the electrical behavior, the externally applied electric field can be chosen that’s why called as field effect transistors. In this, current flows due to majority charge carriers i.e., electrons, hence also known as the uni-polar transistor. It has mainly high input impedance in mega ohms with low frequency conductivity between drain and source controlled by electric field. FETs are highly efficient, vigorous & lesser in cost.
Field effect transistors are of two types i.e., Junction field effect transistors (JFET) and Metal oxide field effect transistors (MOSFET).The current passes between the two channels named as n-channel and p-channel.
Junction Field Effect Transistor (JFET)
The junction field effect transistor has no PN junction but in place of high resistivity semiconductor materials, they form n& p type silicon channels for flow of majority charge carriers with two terminals either drain or a source terminal. In n-channel, flow of current is negative whereas in p-channel flow of current is positive.
Working of JFET:
There are two types of channels in JFET named as: n-channel JFET & p-channel JFET
Here we have to discuss about principal operation of n-channel JFET for two conditions as follows:
First, When Vgs=0,
Apply small positive voltage to drain terminal where Vds is positive. Due to this applied voltage Vds, electrons flow from source to drain cause drain current Id. Channel between drain and source acts as resistance. Let n-channel be uniform. Different voltage levels set up by drain current Id and moves from source to drain. Voltages are highest at drain terminal and lowest at source terminal. Drain is reverse biased so depletion layer wider here.
Vds increases, Vgs=0 V
Depletion layer increases, channel width reduces. Vds increases at level where two depletion region touch, this condition known as pinch –off process & causes pinch off voltage Vp.
Here, Id pinched –off drops to 0 MA & Id reaches at saturation level. Id with Vgs=0 known as drain source saturation current (Idss). Vds increased at Vp where current Id remains same & JFET acts as a constant current source.
Second, When Vgs does not equal to 0,
Apply negative Vgs and Vds varies. The width of depletion region increases, channel becomes narrow and resistance increases. Lesser drain current flows & reaches upto saturation level. Due to negative Vgs, saturation level decreases, Id decreases. Pinch –off voltage continuously drops. Therefore it is called voltage controlled device.
Characteristics of JFET:
The characteristics shown different regions which are as follows:
Ohmic Region: Vgs=0, depletion layer small.
Cut-Off Region: Also known as pinch off region, as channel resistance is maximum.
Saturation or Active Region: Controlled by gate source voltage where drain source voltage is lesser.
Breakdown Region: Voltage between drain and source is high cause breakdown in resistive channel.
p-channel JFET operates same as n-channel JFET but some exceptions occurred i.e., Due to holes, channel current is positive &Biasing voltage polarity needs to be reversed.
Drain current in active region:
Drain source channel resistance: Rds= delta Vds/delta Id
Metal Oxide Field Effect Transistor (MOSFET):
Metal Oxide Field Effect Transistor is also known as voltage controlled field effect transistor. Here, metal oxide gate electrons insulated electrically from n-channel & p-channel by thin layer of silicon dioxide termed as glass.
The current between drain and source is directly proportional to input voltage.
It is a three terminal device i.e., gate, drain & source. There are two types of MOSFET by functioning of channels i.e., p-channel MOSFET & n-channel MOSFET.
There are two forms of metal oxide field effect transistor i.e., Depletion Type & Enhancement Type.
Depletion Type: It requires Vgs i.e., gate-source voltage to switch off & depletion mode is equal to normally closed switch.
Vgs=0, If Vgs is positive, electrons are more & if Vgs is negative, electrons are less.
Enhancement Type: It requires Vgs i.e., gate source voltage to switch on & enhancement mode is equal to normally open switch.
Here, the additional terminal is substrate used in grounding.
Gate source voltage (Vgs) is greater than the Threshold voltage (Vth)
Modes of Biasing For Transistors:
Biasing can be done by the two methods i.e., forward biasing and reverse biasing whereas depending on biasing, there are four different circuits of biasing as follows:
Fixed Base Bias and Fixed Resistance Bias:
In the figure, the base resistor Rb connected between the base and the Vcc. The base emitter junction is forward biased due to voltage drop Rb which leads to flow Ib through it. Here Ib is obtained from:
This results in stability factor (beta +1) which leads to low thermal stability. Here the expressions of voltages and currents i.e.,
Vb=Vbe=Vcc-IbRbVc=Vcc-IcRc=Vcc-VceIc = Beta IbIe=Ic
Collector Feedback Bias:
In this figure, the base resistor Rb connected across collector and base terminal of transistor. Therefore base voltage Vb and collector voltage Vc are similar to each other by this
By these equations, Ic decreases Vc, which reduces Ib, automatically Ic reducing.
Here, (beta +1) factor will be less than one and the Ib leads to reduce amplifier gain.
So, voltages and currents can be given as-
Vb=VbeIc= beta IbIe is almost equals to Ib
Dual Feedback Bias:
In this figure, it is the modified form over the collector feedback basing circuit. As it has additional circuit R1 which increases stability. Therefore, increase in base resistance leads to the variations in beta i.e., gain.
I1=0.1 IcVc= Vcc-(Ic+I(Rb)RcVb=Vbe=I1R1=Vc-(I1+Ib)RbIc= beta IbIe is almost equals to Ic
Fixed Bias With Emitter Resistor:
In this figure, it is same as fixed bias circuit but it has an additional emitter resistor Re connected. Ic increases due to temperature, Ie also increases which again increases the voltage drop across Re. This results in reduction in Vc, reduces Ib which brings iC back to its normal value. Voltage gain reduces by presence of Re.
Ve=Ie ReVc=Vcc – Ic RcVb=Vbe+VeIc= beta IbIe is almost equals to Ic
In this figure, there are two supply voltages Vcc & Vee are equal but opposite in polarity.Here,Vee is forward biased to base emitter junction by Re & Vcc is reverse biased to collector base junction.
Ve= -Vee+Ie ReVc= Vcc- Ic RcVb=Vbe+VeIc= beta IbIe is almost equal to IbWhere, Re>>Rb/betaVee>>Vbe
Which gives a stable operating point.
Emitter Feedback Bias:
In this figure, it uses both collector as feedback & emitter feedback for higher stability. Due to flow of emitter current Ie, the voltage drop occur across emitter resistor Re, therefore the emitter base junction will be forward bias. Here, the temperature increases, Ic increases, Ie also increases. This leads to a voltage drop at Re, collector voltage Vc decreases & Ib also decreases. This results that the output gain will be reduced. The expressions can be given as:
Irb=0.1 Ic=Ib+I1Ve=IeRe=0.1VccVc=Vcc-(Ic+Irb)RcVb=Vbe+Ve=I1R1=Vc-(I1+Ib0Rb)Ic=beta IbIe is almost equal to Ic
Voltage Divider Bias:
In this figure, it uses voltage divider form of resistor R1 & R2 to bias the transistor. The voltage forms at R2 will be base voltage as it forward biases the base-emitter junction. Here, I2= 10Ib.
This is done to neglect voltage divider current and changes occur in value of beta.
Ib=Vcc R2/R1+R2Ve=Ie ReVb=I2 R2=Vbe+Ve
Ic resist the changes in both beta & Vbe which results in a stability factor of 1.In this, Ic increases by increase in temperature, Ie increases by increase in emitter voltage Ve which reduces the base voltage Vbe. This results in decrease base current ib and ic to its actual values.
Applications of Transistors
- Transistors for the most of the parts are used in electronic application such as voltage and power amplifiers.
- Used as switches in many circuits.
- Used in making digital logic circuits i.e., AND, NOT etc.
- Transistors are inserted in everything i.e., stove tops to the computers.
- Used in the microprocessor as chips in which billions of transistors are integrated inside it.
- In earlier days, they are used in radios, telephone equipment’s, hearing head’s etc.
- Also, they are used earlier in vacuum tubes in big sizes.
- They are used in microphones to change sound signals into electrical signals as well.
Transistors are broadly divided into three types: bipolar transistors (bipolar junction transistors: BJTs), field-effect transistors (FETs), and insulated-gate bipolar transistors (IGBTs).What are the 2 main types of transistors? ›
Transistors typically fall into two main types depending on their construction. These two types are bipolar junction transistors (BJT) and Field Effect Transistors (FET).What type of transistor and explain how it works? ›
A transistor consists of two PN diodes connected back to back. It has three terminals namely emitter, base and collector. The basic idea behind a transistor is that it lets you control the flow of current through one channel by varying the intensity of a much smaller current that's flowing through a second channel.What are NPN and PNP transistors? ›
PNP switches ON by a low signal whereas NPN switches ON by a high signal. In PNP transistors, the P represents the polarity of the emitter terminal and N represents the polarity of the base terminal. In NPN, N represents the negatively charged coating of the material whereas P represents the positively charged layer.Are there 3 types of transistors? ›
Transistors are broadly divided into three types: bipolar transistors (bipolar junction transistors: BJTs), field-effect transistors (FETs), and insulated-gate bipolar transistors (IGBTs).What is the most commonly used transistor? ›
The MOSFET is by far the most widely used transistor for both digital circuits as well as analog circuits, accounting for 99.9% of all transistors in the world. The bipolar junction transistor (BJT) was previously the most commonly used transistor during the 1950s to 1960s.What does a NPN transistor do? ›
The NPN transistor is designed to pass electrons from the emitter to the collector (so conventional current flows from collector to emitter). The emitter "emits" electrons into the base, which controls the number of electrons the emitter emits.What are 5 devices that transistors are used in? ›
Transistors are also found in pacemakers, hearing aids, cameras, calculators, and watches. Most of these devices draw their power from tiny batteries. Most spacecraft also rely on microchips, and thus transistors.Which transistor is best and why? ›
N P N transistors provide better conductivity than P N P transistors for this reason. Due to their fast switching rates, N P N transistors are more preferred for switching applications.Can a transistor converts DC to AC? ›
Hence, a transistor cannot convert DC to AC.
Both PNP and NPN transistors can be utilized as switches. A basic terminal transistor can be handled differently from a signal amplifier by biasing both NPN and PNP bipolar transistors by an “ON / OFF” static switch. One of the main uses of the transistor to transform a DC signal “On” or “OFF” is solid-state switches.How does a NPN transistor work as an amplifier? ›
How does a transistor work as an amplifier? A transistor works as an amplifier by taking in a very small weak signal through the base junction and raising the strength of the weak signal. This amplified signal is released through the collector.How do you tell if a transistor is NPN or PNP? ›
The schematic symbols for NPN and PNP transistors are extremely similar. The sole distinction is the orientation of the arrow on the emitter. It points outward in an NPN (on the left) and inward in a PNP (on the right).Why do we use PNP transistor? ›
PNP transistors are used to source current, i.e. current flows out of the collector. PNP transistors are used as switches. These are used in the amplifying circuits. PNP transistors are used when we need to turnoff something by push a button.What is difference between BJT and Mosfet? ›
BJT stands for Bipolar Junction Transistor. MOSFET stands for Metal Oxide Semiconductor Field Effect Transistor. BJT is a three-terminal semiconductor device used for switching and amplification of signals. MOSFET is a four-terminal semiconductor device which is used for switching applications.How do you identify different transistors? ›
The classification of transistors can be easily understood by observing the above tree diagram. Transistors are basically classified into two types. They are: Bipolar Junction Transistors (BJT) and Field Effect Transistors (FET). The BJTs are again classified into NPN and PNP transistors.What type of transistors are used in CPU? ›
They are usually called NMOSFET and PMOSFET. NPN and PNP are two types of transistors. Transistors are semiconductor devices made of doped p-type and n-type junctions.What do the 3 pins of a transistor do? ›
The transistor has three legs, these are the base, collector and the emitter. The emitter is always connected to 0v and the electronics that is to be switch on is connected between the collector and the positive power supply. The base of the transistor is used to switch current through the collector and emitter.What are 2 main applications where transistors are used directly? ›
Transistors are also used for low-frequency, high-power applications, such as power-supply inverters that convert alternating current into direct current. Additionally, transistors are used in high-frequency applications, such as the oscillator circuits used to generate radio signals.What is the main purpose of a transistor? ›
transistor, semiconductor device for amplifying, controlling, and generating electrical signals. Transistors are the active components of integrated circuits, or “microchips,” which often contain billions of these minuscule devices etched into their shiny surfaces.
- Emitter-coupled-logic (ECL) is a BJT logic family that is generally considered the fastest logic available.
- ECL achieves its high-speed operation by employing a relatively small voltage swing and preventing the transistors from entering the saturation region.
NPN transistors are used as a sink to the current i.e., current flows to the Collector. It means the current points inwards. PNP transistors are used as a source to the current i.e., current flows out of the Collector.Which is better PNP or NPN and why? ›
So n-p-n transistors are preferred as they amplify the signals. So the correct answer is that n-p-n transistors are preferred to p-n-p transistors because electrons have higher mobility than holes and hence high mobility of energy.How does a PNP transistor work? ›
In a PNP transistor, the base current which enters into the collector is amplified. The flow of current is typically controlled by the base. Current flows in the opposite direction in the base. In a PNP transistor, the emitter emits “holes”, and these holes are collected by the collector.What are the 3 pins of a transistor called? ›
In general, all transistors have three pins: base, collector, and emitter. Transistor is a bi-polar device that is a transistor with two junctions namely BE and CE DE EE FE.What is an example of transistor in real life? ›
Transistors are used in our day-to-day lives in many forms, which we are aware of as amplifiers and switching apparatuses. As amplifiers, they are being used in various oscillators, modulators, detectors and nearly any circuit to perform a function. In a digital circuit, transistors are used as switches.How many transistors are there? ›
There exists an estimate of the total number of transistors manufactured by 2014: 2.9×1021(13×1021 by 2018).Why do we prefer NPN transistors? ›
The mobility of electrons is better than the mobility of holes. Mobility of electrons is more than hole, so as a result n-p-n transistors are faster than p-n-p that's why they are preferred.Why use a transistor instead of a switch? ›
They're much faster than relays. Switching ranges are typically in the nanosecond (10-9 second) range, many orders of magnitude faster than the equivalent relay. Transistors can behave as analog devices, allowing for signal amplification. They're much smaller than the equivalent relay.How do you choose a transistor in a circuit? ›
- Collector Current. ...
- Saturation Voltage. ...
- Breakdown Voltages. ...
- Current Gain. ...
- Material. ...
Transistors do not create electric current, they only control electric current supplied to them. The input current at the base controls the output current flowing between the emitter and the collector. The transistor can turn on or off if the base current turns on or off.Does transistor amplify AC or DC? ›
Yes, a transistor is used to amplify electronic signals. Bipolar Junction Transistor(BJT) can amplify DC signals. Q.Can a transistor be used as an inverter? ›
Its main function is to invert the input signal applied. If the applied input is low then the output becomes high and vice versa. Inverters can be constructed using a single NMOS transistor or a single PMOS transistor coupled with a resistor.How does a MOSFET work as a switch? ›
The two MOSFETs are configured to produce a bi-directional switch from a dual supply with the motor connected between the common drain connection and ground reference. When the input is LOW the P-channel MOSFET is switched-ON as its gate-source junction is negatively biased so the motor rotates in one direction.How to use 2N2222 transistor as a switch? ›
The 2N2222 transistor is used as a switch in this circuit, with an input resistor driving the transistor and another resistor driving the LED. The transistor starts to work when the switch is closed, and the LED ON and OFF intervals are controlled by the resistance value.How does PNP transistor work as a switch? ›
The concept of PNP transistor as a switch is that, the Current stops flow from collector to emitter only when a minimum voltage of 0.7V is supplied to the base terminal. When there is no voltage on Base terminal it works as a close switch between collector and emitter.What voltage is VCC? ›
The name VCC is used for the memory device supply voltage pin when the supply voltage is nominally 5 V.What type of a device is MOSFET? ›
MOSFET stands for metal-oxide-semiconductor field-effect transistor. It is a field-effect transistor with a MOS structure. Typically, the MOSFET is a three-terminal device with gate (G), drain (D) and source (S) terminals.Is NPN transistor active or passive? ›
Transistors. Although not as obvious as a current or voltage source – transistors are also an active circuit component.Is the 2N2222 transistor a PNP or a NPN transistor? ›
The 2N2222 is a common NPN bipolar junction transistor (BJT) used for general purpose low-power amplifying or switching applications.
A common NPN transistor is the 2N3904. You can easily switch big 12 or 16V loads with this 40V transistor. The current is rated at 200mA which is enough for many small DC motors, relay coils or LEDs. For high-side switch circuits, you need a PNP type transistor.How do you read a transistor with a multimeter? ›
Read how to test the transistor with the meter
Connect the negative probe of the multimeter to the base output (usually it is a black probe), and the positive (red) first to the collector and then to the emitter. Obtaining a value in the range of~500 -1500 Ohm confirms correct operation of the transistor.
An P-Channel mosfet needs a negative Gate - Source voltage to conduct. An NPN transistor needs a positive Base - Emitter current to conduct. An PNP transistor needs a negative Base - Emitter current to conduct. Notice how emitter/collector and source/drain are swapped in the symbols.Why use a MOSFET instead of a transistor? ›
The main advantage of a MOSFET is that it requires almost no input current to control the load current, when compared with bipolar transistors (bipolar junction transistors/BJTs). In an enhancement mode MOSFET, voltage applied to the gate terminal increases the conductivity of the device.Why do we use MOSFET instead of transistor? ›
MOSFET, why should you be named the better transistor? For starters, MOSFETs have faster switching speeds and lower switching losses than BJTs. BJTs have switching frequencies of up to hundreds of kHz, while MOSFETs can easily switch devices in the MHz range.Which is better FET or BJT? ›
BJT is suitable for low current applications. FET is suitable for high current applications. The switching speed of BJT is low. FET has higher switching speed.Which is better NPN or PNP transistor? ›
Thus n-p-n is preferred as in this electrons have higher mobility than holes, which results in high mobility of energy. In a p-n-p transistor, the positive supply line becomes a common point of input and output current, due to which the ground current is positive. This is inconvenient for design and maintenance.How do you know if a transistor is NPN or PNP? ›
The schematic symbols for NPN and PNP transistors are extremely similar. The sole distinction is the orientation of the arrow on the emitter. It points outward in an NPN (on the left) and inward in a PNP (on the right).Where is NPN transistor used? ›
Switching applications are where NPN transistors are most commonly used. This component is used in amplifying circuits. To amplify weak signals, it's used in Darlington pair circuits. NPN transistors are used in applications where a current sink is required.Why use NPN instead of PNP? ›
There are, in fact, some differences, and in most circuit design applications NPN transistors are preferred. This is due to the fact that the “N” substrate can transfer electrons significantly faster than “P” type substrates can transport positive electron holes.
There are two types: NPN (negative -positive-negative) and PNP (positive-negative-positive). The most widely used transistors are NPN transistors as the majority of charge carriers are electrons that are better mobile charge particles with less mass due to which they can easily accelerate.What devices use NPN transistors? ›
NPN transistors are used in some classic amplifier circuits, the same as 'push-pull' amplifier circuits. NPN transistors are used in temperature sensors. NPN transistors are used in very High-frequency applications. NPN transistors are used in logarithmic converters.What is the difference between 2N2222 and 2N3904 transistor? ›
The 2n2222 transistor's main advantage over other similar transistor types is its ability to handle high currents. 2n3904 has a collector current of 200mA, while 2n2222 has a collector current of close to 1ampere, allowing 2n2222 to handle high-value loads like 2n3904.
Can we use BC547 instead of 2N2222? Yes, you can use, for switching just look for Ic(collector current) and Vceo(collector-emitter voltage) in the datasheet.What is the difference between 2N2222 and 2N2222A transistor? ›
The main difference between the two is that the 2N2222A is a higher gain version of the 2N2222. The gain of a transistor is a measure of its amplification ability, and the 2N2222A has a slightly higher gain than the 2N2222, which means it can amplify a signal slightly better.