Today, I'm going to give you an overview of the Different Applications of Transistor and Mosfet. This blog is the continuous blog of the series of Transistors so if you wish to read about any other transistors then you may click HERE.
Bipolar Junction Transistor
A BJT is a bipolar junction transistor, which is capable of handling two polarities (holes and electrons), it can be used as a switch or as an amplifier and is also known as a current-controlled device.
Transistors are used as a switch in a broad range of applications, including connecting high-current or high-voltage devices such as motors, relays, or lights to low-voltage digital ICs or logic gates such as AND gates or OR gates.
Alternatively, the speed of a load, such as a DC motor, may need to be regulated through a sequence of pulses (Pulse Width Modulation). Transistor switches will allow achieving this more quickly and easily than mechanical switches.
Transistor as a Switch in Digital Logic circuit:
The distinction between PNP and NPN is that a PNP transistor switches power (source current) instead of switching ground like an NPN transistor (sinking current).
Darlington Transistor Pair based Rain Alarm
The rain alarm circuit schematic using a Darlington transistor pair (BC547 transistor) is shown.
This circuit is designed in the form of a normal Darlington transistor pair. These transistors are primarily utilized to boost the capacity of current amplification. When water or raindrops fall on the sensor, the base of the transistor is supplied with the current which further gets supplied to Buzzer and causes the alarm to sound.
Transistor as an Amplifier
A transistor functions as an amplifier by amplifying a weak signal. When a DC bias voltage is provided to the emitter-base junction, it remains forward biased. This forward bias is maintained irrespective of the signal's polarity.
Because of the low resistance in the input circuit, every minor change in the input signal results in a large change in the output. The input signal's emitter current goes to the collector current, which then flows through the load resistor RL, causing a high voltage drop across it. As a result, a small input value results in a big output voltage, indicating that the transistor functions as an amplifier.
Some Common General Purpose Transistors:
Some common Power Transistors:
|TIP31C – NPN Power Transistor
|TIP32C - PNP Power Transistor
|TIP127 - Darlington NPN Transistor
|TIP122 - Darlington PNP Transistor
|TIP110-112 Complementary Silicon Power Darlington Transistor
|TIP115-117 Complementary Silicon Power Darlington Transistor
|BJE243 Silicon Power Plastic Transistor
|BJE253 Silicon Power Plastic Transistor
|TIP41TIP41ATIP41BTIP41CComplementary Silicon Plastic Power Transistor
|TIP42TIP42ATIP42BTIP42CComplementary Silicon Plastic Power Transistor
|BD135BD137BD139Plastic medium power Silicon Transistor
|BD136BD138BD140 Plastic medium power Silicon Transistor
|TTC5200 Silicon Triple Diffused Transistor
|TTA1943 Silicon Triple Diffused Transistor
MOSFET stands for Metal Oxide Field Effect Transistor, MOSFET is a three-terminal device with source, base, and drain terminals. It is a sub-classification of the FET transistor.
The MOSFET is Classified into two types based on the type of operations, namely Enhancement mode MOSFET (E-MOSFET) and Depletion mode MOSFET (D-MOSFET)
MOSFET as a Motor Controller
The two MOSFETs are wired together to form a bidirectional switch from a dual supply, with the motor linked between the common drain connection and the ground reference. When the input is set to LOW, the P-channel MOSFET is turned ON because its gate-source junction is negatively biassed, causing the motor to revolve in just one direction. The motor is driven only by the positive +VDD supply rail.
When the input is HIGH, the P-channel device turns OFF, but the N-channel device turns ON because its gate-source junction is positively biassed. Because the motor's terminal voltage has been inverted as it is now fed by the negative -VDD supply rail, it now rotates in the other direction.
MOSFET Motor Control Table
|Motor Stopped (OFF)
|Motor Rotates Forward
|Motor Rotates Reverse
MOSFET used in voltage regulator circuits
In voltage regulator circuits, depletion-type MOSFETs with source-follower connections are employed. The illustration depicts a linear voltage regulator circuit. VL follows the gate voltage(VG), minus the gate-to-source voltage(VGS), in this regulating circuit. Furthermore, when the drain current increases(Id), the gate-source voltage(VGS) also increases. So that the gate voltage remains constant, the source voltage decreases as the load current(IL) increases.
MOSFET as a Chopper
The figure shows how the switching behavior of MOSFETs may be used to construct chopper circuits. By biassing the MOSFET with a square voltage waveform between its gate and source terminals, the DC voltage(VDC), is turned into an AC(VAC) voltage with the same amplitude level. As a result, the MOSFETs alternate between operating in the cut-off and saturation areas.
Power MOSFET in Inverters
With a rectifier and filter, this inverter can deliver high-voltage AC or DC up to several hundred volts. T1's secondary and primary windings, a 12.6 to 440 V power transformer. Q1 and Q2 can be any type of power FET.
Some Common MOSFET’S:
- IRFP460 N-Channel Power MOSFET
- P55NF06 N-Channel Power MOSFET
- IRFZ14 N Channel Power MOSFET
- IRFZ44N N-Channel Power MOSFET
- IRF1405 N-Channel Power MOSFET
- IRF540 N-Channel Power MOSFET
- 2N7000 Small Signal N-MOSFET
- IRF4905 P-Channel Power MOSFET
- IRF9530 P-Channel Power MOSFET
- IRF9533 P Channel Power MOSFET
- IRF5305 P-Channel Power MOSFET
- IRF9520 P-Channel Power MOSFET
- IRF9530 P-Channel Power MOSFET
- IRF9Z34N P-Channel Mosfet