electronics devices& instrumentation lab (18ecl37)

VSM’s

Somashekhar R Kothiwale Institute of

Technology, Nipani-591237

Department of Electronics &

Communication Engg

Electronics Devices & Instrumentation

Laboratory Manual

18ECL37

BY:

Prof. Santosh I Kolaki

Asst Prof, ECE Dept

VSMSRKIT, Nipani

Electronics Devices& Instrumentation Lab (18ECL37)

ECE Dept, VSMSRKIT, Nipani

ELECTRONIC DEVICES AND INSTRUMENTATION LABORATORY

Laboratory Code 18ECL37

CIE Marks 40 SEE Marks 60

Laboratory Experiments

PART A : Experiments using Discrete components

1 Conduct experiment to test diode clipping and clamping circuits (positive/negative)

2 Half wave rectifier and Full wave rectifier with and without filter

3 Characteristics of Zener diode

4 Characteristics of LDR and Photo diode and turn on an LED using LDR

5 Static characteristics of SCR.

6 SCR Controlled HWR and FWR using RC triggering circuit

7 Measurement of Resistance using Wheatstone and Kelvin’s bridg

PART-B : Simulation using EDA software

1 Input and Output characteristics of BJT CE configuration and evaluation of parameters

2 Transfer and drain characteristics of a JFET and MOSFET.

3 UJT triggering circuit for Controlled Full wave Rectifier

4 Design and simulation of Regulated power supply



Experiment No: 01

1. DIODE CLIPPING AND CLAMPING

Aim:

Conduct experiment to test diode clipping (single/double ended) and clamping circuits

(positive/negative)

Theory:

The Diode Clipper, also known as a Diode Limiter, is a wave shaping circuit that takes an

input waveform and clips or cuts off its top half, bottom half or both halves together.

Clipping circuits (also known as limiters, amplitude selectors, or slicers), are used to remove

the part of a signal that is above or below some defined reference level.

Clamping circuits, also known as dc restorers or clamped capacitors, shift an input signal by

an amount defined by an independent voltage source. While clippers limit the part of the

input signal that reaches the output according to some reference level(s), the entire input

reaches the output in a clamping circuit – it is just shifted so that the maximum (or

minimum) value of the input is “clamped” to the independent source.

Positive clipper: Positive clipper means positive part of input will be clipped off

withoutdistorting the remaining negative part of the input. In this diode clipping circuit, the

diode is forward biased (anode more positive than cathode) during the positive half cycle of

the sinusoidal input waveform. For the diode to become forward biased, it must have the

input voltage magnitude greater than +0.7 volts (0.3 volts for a germanium diode). When

this happens, the diodes begins to conduct and holds the voltage across itself constant at

0.7V until the sinusoidal waveform falls below this value. Thus, the output voltage which is

taken across the diode can never exceed 0.7 volts during the positive half cycle.

Negative clipper: Negative clipper means negative part of input will be clipped off

withoutdistorting the remaining positive part of the input. During the negative half cycle, the

diode is reverse biased (cathode more positive than anode) blocking current flow through

itself and as a result has no effect on the negative half of the sinusoidal voltage which passes

to the load unaltered. Thus, the diode limits the positive half of the input waveform and is

known as a positive clipper circuit.



1. Positive peak clipper:

Circuit Diagram Expected Waveform

Calculation:

Theoretically:

Vo= Vγ+VR

= 0.7+1.5

=2.2V

Practically:

V0= ______________

2. Negative peak clipper:

Circuit Diagram:

Calculation:

Theoretically: Practically:

Vo= -Vγ-VR = -0.7-1.5

=-2.2V V0= ______________



3. Double Ended Clipper

Let VR= 1.5V

Calculation:

Theoretically:

For positive half cycle for negative half cycle:

Vo= Vγ+VR Vo= -Vγ-VR

= 0.7+1.5= 2.2V = -0.7-1.5 =-2.2V

Practically:

For positive half cycle for negative half cycle:

V0= ______________ V0= ______________



Procedure:

1. Make the connection as per the circuit diagram.

2. Apply input sine wave from signal generator of frequency 1KHz

3. Observe the output on CRO

4. Verify theoretical and practical values

5. Draw the waveforms

Conclusion: Clipper circuits using diodes are studied and verified



Clamping Circuits:

Theory:

A Clamper circuit can be defined as the circuit that consists of a diode, a resistor and a capacitor

that shifts the waveform to a desired DC level without changing the actual appearance of the

applied signal.

POSITIVE CLAMPER CIRCUIT

A Clamping circuit restores the DC level. When a negative peak of the signal is raised above to

the zero level, then the signal is said to be positively clamped.A Positive Clamper circuit is one

that consists of a diode, a resistor and a capacitor and that shifts the output signal to the positive

portion of the input signal

NEGATIVE CLAMPER

A Negative Clamper circuit is one that consists of a diode, a resistor and a capacitor and that

shifts the output signal to the negative portion of the input signal

Procedure:

1. Make the connection as per the circuit diagram.

2. Apply input sine wave from signal generator of frequency 1KHz

3. Observe the output on CRO in DC mode

4. Verify theoretical and practical values

5. Draw the waveforms

Result: Clamping Circuits designed and observed the waveforms.



Positive Clamper Negative Clamper

Nature of Graph:

Calculation:

Positive Clamper Negative Clamper

Theoretically Theoretically

(+Ve half cycle) (-Ve half cycle) (+Ve half cycle) (-Ve half cycle)

V0= 2Vm-(Vγ+VR) = V0= -(Vγ+VR) = V0= (Vγ+VR) = V0=-( 2Vm-(Vγ+VR))=

Practically Practically

Vo= Vo= Vo= Vo=



Experiment No: 02

2.DIODE RECTIFIER CIRCUITS

Aim: Set up the following rectifiers with and without filters:

(a) Half Wave Rectifier (b) Full Wave Rectifier

To determine ripple factor and conversion efficiency

Theory: A rectifier converts ac voltage to pulsating dc voltage. Thus the p-n junction diode,

which conducts only in one direction, acts as a rectifier. Diode rectifier circuits are one of the

key circuits used in electronic equipment. They can be used in power supplies, RF signal

demodulation, RF power sensing and very much more. Using one or more diodes, following

rectifier circuits can be designed.

1. Half wave rectifier

2. Full wave rectifier and

3. Bridge rectifier.

Half wave rectifier circuit: This is the simplest form of rectifier. Often using only, a single

diode is blocks half the cycle and allows through the other. As such only half of the waveform is

used. The half wave diode rectifier is used in a variety of ways and in a host of different types of

circuit.

Power rectification: One of the most obvious ways for a half wave diode rectifier to be used

is within a power rectifier. A line or mains power input normally passes through a transformer

to transform the voltage to the required level.

Signal demodulation: A simple half wave diode rectifier can be used for signal

demodulation of amplitude modulated signals. The rectification process enables the amplitude

modulation to be recovered.

Signal peak detector: The simple half wave diode detector can be used as a peak detector,

detecting the peak of an incoming waveform.

Full wave rectifier circuit: This form of rectifier circuit uses both halves of the waveform. This

makes this form of rectifier more effective, and as there is conduction over both halves of the

cycle, smoothing becomes much easier and more effective. There are two types of full

averectifier

Circuit Diagram:



Half Wave Rectifier

Without filter: With Filter:

FULL WAVE RECTIFIER:

Withou filter With Filter:

EXPECTED WAVEFORMS:

HWR WITH OUT FILTER

Two diode centre taped transformer full wave rectifier: The two diode version of the full

wave rectifier circuit requires a centre tap in the transformer. When vacuum tubes /



thermionic valves were used, this option was widely used in view of the cost of the valves.

However with semiconductors, a four diode bridge circuit saves on the cost of the centre

tapped transformer and is equally effective.

Bridge full rectifier circuit: This is a specific form of full wave rectifier that utilises four

diodes in a bridge topology. Bridge rectifiers are widely used, especially for power

rectification, and they can be obtained as a single component contain the four diodes

connected in the bridge format.

The filter is an electronic circuit composed of capacitor, inductor or combination of both and

connected between the rectifier and the load to convert pulsating dc to pure dc. A filter circuit is

a device that removes ac component of rectifier output but allows the dc component to reach the

load. The filter circuit is installed between the rectifier and the load. Filters serve a critical role in

many common applications. Such applications include power supplies, audio electronics, and

radio communications.

Procedure:

1. Connection are made as per circuit diagram

2. Note down the maximum value Vm from CRO

3. Calculate DC output, RMS output, DC output current and RMS output current

4. Determine ripple factor

5. Connect the capacitor filter across load resistor repeat step 1 to 4

Conclusion:

HWR and FWR circuits are studied and verified.



HWR WITH FITER

FWR WITH OUT FILTER

FWR WITH FILTER



Calculation:

HWR without filter HWR with filter

1 Vm= 1 Vm=

2 VDC= (Vm/π) = 2 VDC= (Vm/π) =

3 Vrms= Vm/2= 3 Vrms= Vm/2=

4 RF=√ (Vrms/ VDC)2-1= 4 RF=√ (Vrms/ VDC)

2-1=

Note: Ripple factor for HWR is 1.21

FWR without filter FWR without filter

1 Vm= 1 Vm=

2 VDC= (2Vm/π) = 2 VDC= (2Vm/π) =

3 Vrms= Vm/√2= 3 Vrms= Vm/√2=

4 RF=√ (Vrms/ VDC)2-1= 4 RF=√ (Vrms/ VDC)

2-1=

Note: Ripple factor for FWR is 0.48



Experiment No: 03

3.ZENER DIODE CHARACTERISTICS

Aim: To study the Characteristics of a Zener diode and design a Simple Zener voltage regulator

determine line and load regulation

Theory:

A Zener diode allows current to flow from its anode to its cathode like a normal

semiconductor diode, but it also permits current to flow in the reverse direction when its "Zener

voltage" is reached. Zener diodes have a highly doped p-n junction. Normal diodes will also

break down with a reverse voltage but the voltage and sharpness of the knee are not as well

defined as for a Zener diode. Also normal diodes are not designed to operate in the breakdown

region, but Zener diodes can reliably operate in this region.

Zener Diode as Voltage Regulators:

The function of a regulator is to provide a constant output voltage to a load connected in

parallel with it in spite of the ripples in the supply voltage or the variation in the load current and

the zener diode will continue to regulate the voltage until the diodes current falls below the

minimum IZ(min) value in the reverse breakdown region. It permits current to flow in the

forward direction as normal, but will also allow it to flow in the reverse direction when the

voltage is above a certain value - the breakdown voltage known as the Zener voltage. The Zener

diode specially made to have a reverse voltage breakdown at a specific voltage. Its

characteristics are otherwise very similar to common diodes. In breakdown the voltage across the

Zener diode is close to constant over a wide range of currents thus making it useful as a shunt

voltage regulator.

The purpose of a voltage regulator is to maintain a constant voltage across a load

regardless of variations in the applied input voltage and variations in the load current. A typical

Zener diode shunt regulator is shown in Figure 3. The resistor is selected so that when the input

voltage is at VIN(min) and the load current is at IL(max) that the current through the Zener diode

is at least Iz(min). Then for all other combinations of input voltage and load current the Zener

diode conducts the excess current thus maintaining a constant voltage across the load. The Zener

conducts the least current when the load current is the highest and it conducts the most current

when the load current is the lowest.



Zener diode characteristics:

Forward bias :

Reverse bias:

Model Graph:



Procedure:

Forward Biased Condition:

1. Connect the Zener diode in forward bias i.e; anode is connected to positive of the power

supply and cathode is connected to negative of the power supply as in circuit.

2. Use a Regulated power supply of range (0-30) V and a series resistance of 1kΏ.

3. For various values of forward voltage (Vf) note down the corresponding values of forward

Current (If).

Reverse biased condition:

1. Connect the Zener diode in Reverse bias i.e; anode is connected to negative of the power

supply and cathode is connected to positive of the power supply as in circuit.

2. For various values of reverse voltage (Vr ) note down the corresponding values of reverse

current ( Ir ).



Tabular column:

FORWARD BIAS REVERSE BAIS

No Voltage (Vf) in V Current (If) in mA No Voltage (Vr) In V Current (Ir) in mA

Conclusion: Characteristics of Zener diode studied and verified



Experiment No: 04 Date:

4.A)CHARACTERISTICS OF LDR AND PHOTODIODE

Aim: To study the characteristics of LDR and Photo diode and turn on an LED using LDR

Circuit Diagram:

Theory:

The resistance value of the Light Dependent Resistor is dependent on amount of light falls on it.

LDR is made by depositing a thin film of cadmium sulphide or cadmium selenide on a substrate

of ceramics. The film is deposited in zig zag fashion to from a strip. The longer the strip the

greater is the value of resistance. When light falls on the strip resistance decreases and when on

dark resistance is high.

Procedure:

1. Arrange the bulb and LDR as shown in the experimental setup.

2. Keep the distance between the bulb and LDR exactly at 20cm and then measure the resistance

of the LDR using multimeter.

3. Move to LDR away from the bulb in step of 10cm and measure the resistance of the LDR and

tabulate the readings.

5. Plot a graph of Distance V/s Resistance.



Observation Table: Model Graph:

Turn on an LED using LDR:

Result: The characteristic of LDR is studied and is observed that resistance of LDR is low when

it is under light and resistance is high when it is under dark.

Sl.No Distance in cm Resistance in

Ohm



4. B) CHARACTERISTICS OF PHOTODIODE

Theory:

Photodiode:

A silicon photodiode is a solid state light detector that consists of a shallow diffused P-N

junction with connections provided to the outside world. When the top surface is illuminated,

photons of light penetrate into the silicon to a depth determined by the photon energy and are

absorbed by the silicon generating electron-hole pairs.

The electron-hole pairs are free to diffuse (or wander) throughout the bulk of the photodiode

until they recombine. The average time before recombination is the “minority carrier lifetime”.

At the P-N junction is a region of strong electric field called the depletion region. It is formed by

the voltage potential that exists at the P-N junction. Those light generated carriers that wander

into contact with this field are swept across the junction.

If an external connection is made to both sides of the junction a photo induced current will flow

as long as light falls upon the photodiode. In addition to the photocurrent, a voltage is produced

across the diode. In effect, the photodiode functions exactly like a solar cell by generating a

current and voltage when exposed to light.

Procedure:

1. .Rig up the circuit as per the circuit diagram.

2. Maintain a known distance (say 5cm) between the DC bulb and the photodiode.

3. Set the voltage of the bulb(say,2V),vary the voltage of the diode in step of 1V and note own

the corresponding diode current, Ir.

4. Repeat the above procedure for the various voltages of DC bulb.

5. Plot the graph :Vr v/s Ir for a constant DC bulb voltage



Circuit Diagram:

Nature of Graph

Tabular Column:

Without light With light

Reverse

voltage (Vr)

Reverse

current (Ir)

Reverse

voltage (Vr)

Reverse

current (Ir)

Conclusion: Characteristics of Photodiode are studied and verified



Experiment No: 05 Date:

5. STATIC CHARACTERISTICS OF SCR

Aim: 1) To plot the static characteristics of the given SCR.

2) To find Latching and Holding current of the given SCR.

THEORY:

An SCR is a 4-layer, 3-junction, 3-terminal device. When anode is positive w.r.t cathode, the

curve between VAK and IA is called the forward characteristics. During forward bias condition,

the junction J2 is reverse biased and when across J2 above break over voltage (VBO), J2 breaks

down and heavy current will flow in the device. Hence a load resistance is always connected in

series with the SCR to limit the anode current to safe value. Latching current is the minimum

anode current required to turn ON SCR without gate current. Holding current is the maximum

anode current at which SCR turns OFF from ON condition, with gate open. The diodes are

termed as uncontrolled rectifiers as they conduct (during forward bias condition without

any control) whenever the anode voltage of the diode is greater than cathode voltage. Hence,

the thyristor is also called as controlled rectifier or silicon controlled rectifier.

Procedure:

A) To Plot V.I Characteristics:

1. Make the connections as per the circuit diagram.

2. Switch ON the regulated power supply. Apply some constant voltage say 30V by varying

VAK source.

3. Gradually increase the gate current by varying VGK source till the SCR becomes ON.

Note down the corresponding value of IG from the milliammeter. Then decrease VAK

and VGK to minimum.

4. Set gate current equal to noted value in step 3 by varying VGK source.

5. Gradually increase VAK in steps of 2V and for each step note down the value of VAK

and IA , and then reduce VAK to minimum.

6. Set gate current to some other value (preferably higher than that of the value set in step 3)

7. Repeat step 5.

8. Plot a graph of VAK versus IA for different values of IG



Circuit diagram:

Model Graph:

.



B) To find Latching current (IL):

1. Keep proper VAK to trigger SCR by gate current. Then trigger SCR by applying gate current.

2. Gradually decrease VAK in steps and at each step switch-off the gate supply (i.e. VGK

source) and observe that, whether device remains in the ON state or not.

3. Repeat step 2 (by trial and error method) till the SCR jumps to blocking state, and then note

down the minimum value of IA which keeps device in the on state as Latching current.

C) To Find Holding current (IH):

1. Keep proper VAK to trigger SCR by gate current. Then trigger SCR by applying gate current.

2. Switch-Off VGK source permanently. Now gradually decrease VAK and note down the

minimum value of IA below which, the device suddenly falls from ON-state to OFF- state as

Holding current.

Conclusion: . Static Characteristics of SCR are studied and verified

.



Tabular Column:

I G1=____mA I G2=____mA

IL = ______mA

IH = ______mA

Sl No. VAK in volts IA in mA

Sl No. VAK in volts IA in mA



Experiment No: 06

6. RC HALF AND FULL WAVE FIRING CIRCUIT

AIM: To study the static characteristics of RC Half and Full wave firing circuit.

APPARATUS: RC Firing circuit Study unit.

THEORY:

In the negative half cycle of the AC supply, diode D2 is forward biased. It will short circuit the

potentiometer “R’’ and the capacitor “C’’ is charged to negative peak voltage through D2 as

shown in fig (a). with its upper plate negative with respect to its lower plate . In the positive half

cycle, D2 is reverse biased. The capacitor “C’’ will charged through “R’’ to the trigger point of

the thyristor in a time determined by the RC time constant and the rising anode voltage(see

fig(b)). The diode D1 will isolate and protect the gate cathode junction against reverse (negative)

voltage.

As soon as the capacitor voltage become sufficiently positive to forward bias. Diode D1 and the

gate cathode junction of thyristor will be turned on. As soon as the thyristor is turned on, the

voltage across it reduced to a very low value and the gate current goes to zero.

PROCEDURE: (HWR)

1) Make the connections as given in the circuit diagram.

2) Connect a Resistance of 50 ohms between the load points.

3) Vary the control pot(R) and observe the voltage waveforms across load, SCR and at different

points of the

circuit.

4) Note down the output voltage across the Load for different values of firing angle in degree.

5) Calculate the theoretical and practical output voltage.

6) Draw the graph for input wave form, output waveforms across SCR and Load



RC HALF WAVE FIRING CIRCUIT:

Circuit diagram:

Connection Diagram for RC Half Wave Firing circuit:

.



Waveforms for RC Half Wave:

Waveforms across input and load: Waveforms across load and SCR:



Procedure (FWR)

1) Make the connections as given in the circuit diagram.

2) Connect a Rheostat of 100 ohms between the load points.

3) Vary the pot and observe the voltage waveforms across load, SCR and at different points of

the circuit.

4) Note down the output voltage across the Load for different values of firing angle in degree.

5) Calculate the theoretical and practical output voltage.

6) Draw the graph for input wave form, output waveforms across SCR and Load

Conclusion :Half and full wave R & RC triggering circuit have been rigged up and output

waveforms have been plotted.



RC Full Wave Firing Circuit

Circuit diagram:

Connection diagram for RC Full Wave Firing:



Waveforms for RC Full Wave

Waveforms across input and load:

Waveforms across load and SCR:



Experiment No: 07

7. A) Wheatstone Bridge

Aim: Measurement of unknown resistance using Wheatstone Bridge

Theory:

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical

resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown

component. The primary benefit of the circuit is its ability to provide extremely accurate

measurements

For measuring accurately any electrical resistance Wheatstone bridge is widely used.

There are two known resistors, one variable resistor and one unknown resistor connected in

bridge form as shown below. By adjusting the variable resistor the current through the

Galvanometer is made zero. When the current through the galvanometer becomes zero, the ratio

of two known resistors is exactly equal to the ratio of adjusted value of variable resistance and

the value of unknown resistance. In this way the value of unknown electrical resistance can

easily be measured by using a Wheatstone Bridge.

Procedure:

1. Make the connection as per the circuit diagram

2. Adjust the DRB value to make galvanometer pointer exactly zero

3. Determine unknown resistance value by using below formula

Rx= R2*R3(DRB)/ R1

https://en.wikipedia.org/wiki/Electrical_circuit

https://en.wikipedia.org/wiki/Electrical_resistance



https://en.wikipedia.org/wiki/Bridge_circuit

https://www.electrical4u.com/types-of-resistor/

https://www.electrical4u.com/variable-resistors/

https://www.electrical4u.com/electric-current-and-theory-of-electricity/

https://www.electrical4u.com/what-is-electrical-resistance/



Circuit Diagram:

Tabular Column:

No R1 R2 R3

(DRB) Rx= R2*R3(DRB)/ R1 Actual Resistor value

1

2

3

Conclusion: Measurement of unknown resistance using Wheatstone bridge is determined



7. B) Wheatstone Bridge

Aim: Measurement of unknown resistance using Kelvin Bridge

Theory:

Wheatstone bridge use for measuring the resistance from a few ohms to several kilo-

ohms. But error occurs in the result when it is used for measuring the low resistance. This is

the reason because of which the Wheatstone bridge is modified, and the Kelvin bridge obtains.

The Kelvin bridge is suitable for measuring the low resistance. The P and Q is the first ratio of

the arm and p and q is the second arm ratio. The ratio of the arms p and q are used to connect

the galvanometer to reduce the effect of connecting lead. The ratio of p/q is made equal to the

P/Q. Under balance condition zero current flows through the galvanometer. Unknown resistance

is determined by R= (P/Q)*S

Procedure:

1. Make the connection as per the circuit diagram

2. Adjust the DRB value to make galvanometer pointer exactly zero

3. Determine unknown resistance value by using below formula

R= (P/Q)*S

https://circuitglobe.com/wheatstone-bridge.html

https://circuitglobe.com/what-is-a-resistance.html



Circuit Diagram:

Tabular Column:

No P Q S (DRB) R= (P/Q)*S Actual Resistor value

1

2

3

Conclusion: Measurement of unknown resistance using Kelvin Bridge is determined



PART B: SIMULATION USING EDA

TOOLS



Experiment No: 1

1. INPUT & OUTPUT CHARACTERISTICS OF BJT CE CONFIGURATION

AIM: To simulate input and output I-V characteristics of BJT common emitter configuration.

APPARATUS: PC loaded with PSpice tool

THEORY:

INPUT CHARACTERISTICS:

The input characteristics are obtained as family of IB -VBE curves at constant VCE. Since the base

emitter junction is forward biased, the IB -VBE characteristics resemble that of a forward biased

junction diode. The increase in VCE causes increase in reverse bias to C-B junction. This causes

the depletion region to widen and penetrate into the base region more reducing effective base

width. This results in less base current to flow and hence increase in VCE causes the

characteristics to shift to the right.

OUTPUT CHARACTERISTICS:

These characteristics are obtained as family of IC-VCE at different values of IB. At small values of

VCE, the collector voltage is less than that of base causing CB junction to get forward biased. This

causes the transistor to enter saturation region where both the junctions are forward biased. For a

given base bias, increase in VCE reduces the forward bias and eventually reverse bias the CB

junction. This now results in narrowing the base width and thereby reducing base current. This

makes the collector current to slightly increase at higher values of VCE causing the characteristics

to exhibit some slope. This is Early effect.



CIRCUIT DIAGRAM:





PROCEDURE:

1. Design your circuit in schematics. This can be divided into following substeps. 1). First

insert all the parts without considering their values (for example, place a resistor without

considering the resistance value of it, etc.).

2. Make the necessary rotations for the parts, and move the parts to appropriate locations.

3. Make all the necessary wire connections.

4. Mark the nodes you are interested in with labels.

5. Set the values for all the parts, for example, the resistance values of resistors, the width

(W) and length (L) of transistor, etc.

6. Define the SPICE model for NPN and PNP transistors.

7. Setup analysis to tell SPICE what simulation you need (transient analysis, DC sweep,

etc.)

8. Run the simulation.

9. Observe the simulation results (traces of signals) in OrCAD PSpice.



SIMULATION RESULT:





Experiment No: 2

2. TRANSFER & DRAIN CHARACTERISTICS OF A JFET & MOSFET

Aim:To simulate transfer and drain characteristics of a JFET and MOSFET.

APPARATUS REQUIRED: PC loaded with PSpice tool

THEORY:

JFET:Junction gate field-effect transistor are three-terminal semiconductor devices that can be

used as electronically-controlled switches, amplifiers, or voltage-controlled resistors. Unlike

bipolar transistors, JFETs are exclusively voltage-controlled in that they do not need

a biasing current. Electric charge flows through a semiconducting channel

between source and drain terminals. By applying a reverse bias voltage to a gate terminal, the

channel is "pinched", so that the electric current is impeded or switched off completely. A JFET is

usually ON when there is no voltage between its gate and source terminals. If a potential difference

of the proper polarity is applied between its gate and source terminals, the JFET will be more

resistive to current flow, which means less current would flow in the channel between the source

and drain terminals. JFETs are sometimes referred to as depletion-mode devices as they rely on the

principle of a depletion region which is devoid of majority charge carriers; and the depletion

region has to be closed to enable current to flow.

MOSFET:The MOSFET (Metal Oxide Semiconductor Field Effect Transistor) transistor is a

semiconductor device which is widely used for switching and amplifying electronic signals in the

electronic devices. The MOSFET is a core of integrated circuit and it can be designed and

fabricated in a single chip because of these very small sizes. The MOSFET is a four terminal

device with source(S), gate (G), drain (D) and body (B) terminals. The body of the MOSFET is

frequently connected to the source terminal so making it a three terminal device like field effect

transistor. The MOSFET is very far the most common transistor and can be used in both analog

and digital circuits. The MOSFET works by electronically varying the width of a channel along

which charge carriers flow (electrons or holes). The charge carriers enter the channel at source and

exit via the drain. The width of the channel is controlled by the voltage on an electrode is called

gate which is located between source and drain. It is insulated from the channel near an extremely

thin layer of metal oxide

https://en.wikipedia.org/wiki/Semiconductor

https://en.wikipedia.org/wiki/Electronics

https://en.wikipedia.org/wiki/Switch


https://en.wikipedia.org/wiki/Biasing

https://en.wikipedia.org/wiki/Electric_charge

https://en.wikipedia.org/wiki/Voltage

https://en.wikipedia.org/wiki/Electric_current

https://en.wikipedia.org/wiki/Depletion-mode



CIRCUIT DIAGRAM:

JFET INPUT CHARACTERISTICS: JFET OUTPUT CHARACTERISTICS:

SIMULATION RESULT:

JFET INPUT CHARACTERISTICS: JFET OUTPUT CHARACTERISTICS:



CIRCUIT DIAGRAM:

MOSFET CHARACTERISTICS:

INPUT CHARACTERISTICS: OUPUT CHARACTERISTICS:



PROCEDURE:











etc.)

8. Run the simulation.

9. Observe the simulation results (traces of signals) in OrCAD PSpice.



Experiment No: 3

3. UJT TRIGGERING CIRCUIT FOR CONTROLLER RECTIFIERS

AIM: To design and simulate UJT triggering circuit using PSpice.


THEORY:

A unijunction transistor (UJT) is an electronic semiconductor device that has only one

junction. The UJT has three terminals: an emitter (E) and two bases (B1 and B2). The base is

formed by lightly doped n-type bar of silicon. Two ohmic contacts B1 and B2 are attached at its

ends. The emitter is of p-type and it is heavily doped. The resistance between B1 and B2, when

the emitter is open-circuit is called interbase resistance. Initially the capacitor charges through R

whose voltage is applied to the emitter of UJT. When the capacitor voltage reaches peak point

voltage of UJT. the UJT will switch to on condition. Now the capacitor discharges through the

output resistance. Thus the pulse is generated in the circuit.

PROCEDURE:



considering the resistance value of it, etc.)








etc.)

8. Run the simulation. Observe the simulation results (traces of signals) in OrCAD PSpice

https://www.pantechsolutions.net/power-electronics/r-rc-ujt-triggering







CIRCUIT DIAGRAM:



Experiment No: 4

4. DESIGN & SIMULATION OF REGULATED POWER SUPPLY

Aim: To design and simulate regulated power supply using PSpice.


THEORY:

A regulated DC voltage source is obtained from a AC voltage source is easily by rectification.

AC voltage is of 230V r.m.s. is easily available. This voltage is step downed by a transformer.

Then rectified by diodes. If a center taped transformer is used only two diode is sufficient for full

wave-rectification. If transformer is not a center taped bridge rectifier is used. After rectification

the voltage is DC but contains high ripple. A LC or RC filter is used at the output to filter the

high ripple voltage. Now this voltage can be used for DC supply. But this DC source is not

regulated means if the input AC voltage changes output also changes. To get a regulated output

zener diode regulation and Voltage Regulator may be used

PROCEDURE:




2. Make the necessary rotations for the parts and move the parts to appropriate locations.







etc.)

8.Run the simulation. Observe the simulation results (traces of signals) in OrCAD PSpice



CIRCUIT DIAGRAM:

SIMULLATION RESULT:

electronics devices& instrumentation lab (18ecl37)

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