lab manual - site.iugaza.edu.ps

Prepared by

Eng. Deeb Tubail

Eng. Amani Abu Reyala

IUG - 2009

Electronics II (EELE 3120)

)٢(مختبر إلكترونيات

Lab Manual

ENG. AMANI ABU REYALA Electronics II ENG.DEEB ASAD TUBAIL

Lab Manual

٢

AAAACKNOWLEDGMENTCKNOWLEDGMENTCKNOWLEDGMENTCKNOWLEDGMENT

We dedicate this work to our lovely teachers

Eng. Moayed Al-mobaied

Eng. Manhal Abu safer

Who put the keystone for this material

Eng. Deeb A. Tubail

Eng. Amani S. Abu Reyala


Lab Manual

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Laboratory Safety

Experiments in this laboratory will be conducted in strict accordance with following

list of regulations, procedures and comments in order to promote a professional and

safe approach to the laboratory experience. Additionally, laboratory safety rules

apply during all experiments. If you are not sure of the operation of equipment or

laboratory procedure, particularly those which might compromise personal safety

and the safety of your laboratory partners, do not hesitate to ask your laboratory

instructor for assistance. The following rules must be strictly adhered to during the

course of your laboratory experiment:

1. Be calm and relaxed, while working in Lab.

2. No paper lying on table or nearby circuits. 3. No smoking, no food and no drinks permitted inside the laboratory.

4. Wear proper clothing and insulated footwear to the laboratory.

5. Do not use wet hands or stand on a wet floor while making electrical

connections.

6. Do not place personal belongings (books, coat, etc.) on the laboratory

equipment.

7. Keep your work area clean and organized.

8. Use only that equipment required for a particular experiment specified.

9. Do not use damaged or poorly insulated wires or equipment.

10. Properly ground all equipment.

11. Thoroughly check all connections before applying power.

12. Turn power off when making changes to your experiment.

13. Discharge capacitors by shorting with resistor.

14. Do not energize equipment until give permission.

15. Do not touch 120V electrical outlets or the terminals of any energized

electrical connection.

16. Report any accident to your instructor immediately.

17. Work deliberately and carefully.

18. In the event of a power failure, turn off the power switched to all equipment

immediately and wait further instructions.

19. After you are done with your experiment, turn all main switches off.

20. Failure to follow safety instructions can cause serious bodily injury or death.


Lab Manual

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The Islamic University of Gaza

Faculty of Engineering

Department of Electrical Engineering

Electronics II Laboratory (EELE 3120)

Laboratory Experiments:

The lab will cover the following experiments:

1. Multistage amplifier- cascade and cascode connection.

2. Multistage amplifier- current mirror and Darlington.

3. AC analysis of JFET.

4. Frequency response of BJT.

5. Frequency response of JFET.

6. Differential amplifier.

7. Operational amplifier- part 1.

8. Operational amplifier- part 2.

9. Power transistor.

10. Silicon controlled rectifier

11. Diac and Triac.

Objectives:

• This course aims to give a practical view on your theoretical subject.

• To be familiar with multistage amplifier connections.

• To get to know the ac analysis of JFET.

• To be familiar with the frequency response of BJT and JFET transistors.

• To get to know operational and differential amplifiers

• To be familiar with power transistors, SCR, Diac and Triac.

References: Robert L. Boylestad, Louis Nashelsky, “ Electronic Circuits, Devices and Circuit Theory , ” 9

th edi!on, Pren!ce Hall, 2006.


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Grades:

10 Pts Lab work……………………….

20 Pts Midterm Exam………………....

30 Pts Final Exam………………….....

15 Pts Reports…………………………

5 Pts Prelabs…………………………

20 Pts Project

Lab Policy:

• No late reports or pre-labs will be accepted

• Avoid copy-paste Technology

• Reports should be done individually.

• Mid term Exam will be at the end of Lab(5)

Office Hours: Open-door policy, by appointment or as posted.


Lab Manual

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PSpice with OrCAD Capture

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Objectives :

Provide an introduction to the basics of using the PSpice circuit analysis

software package.

Get a review about installing of OrCAD software program.

Be familiar with different types of analyses and simulation.

Introduction:

PSpice is a powerful general purpose analog and mixed-mode circuit simulator that

is used to verify circuit designs and to predict the circuit behavior. Its name implies '

Simulation Program for Integrated Circuits Emphasis ' .

It is recommended to simulate all circuits you will connect in the lab to get the ability

of predicting the practical results thus the intended ideas become more obvious.

PSpice allows you to do different types of analysis according to the purpose of each

circuit. These types are DC bias, DC Sweep, Transient with Fourier analysis, AC

analysis, Parameter sweep and Temperature sweep.

In this lab, we will use three basic types of circuit analysis; transient analysis, AC

frequency sweep and DC sweep. Briefly, these may be described as follows:

The “DC sweep” analysis produces a graph of the voltage (or current) at a

selected point in the circuit as the value of one of the DC sources in the circuit

is swept over some range.

The “AC Sweep” analysis produces a graph of the magnitude of the

sinusoidal voltage versus frequency at a selected point in the circuit.

The “Time Transient” analysis produces a graph of the output voltage (or

current) versus time at a selected point in the circuit. Applied sources are

characterized by a time sequence of samples of a voltage or current

waveform.


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Procedure :

1. Install OrCAD Program on your computer from your own CD. Try to follow

the instruction of downloading.

2. from ʹ Programsʹ directory, click : OrCAD release 9, Capture CIS. The main

page of OrCAD will appear.

3. To open anew project, click : File, New, Project.

4. In the dialog box, type the name of your project. Check the ʹ Analog or Mixed

– Signal Circuit Wizard ʹ . Browse to the path to be used to store the project at

location Field. Click OK.

5. Another dialog box will appear, it asks you to add libraries you need at your

project. Initially the default libraries are sufficient so Click Finish.

6. A schematic page will appear. Click near the right edge of the screen Then a

tool bar should appear.

Simulation Examples:

As mentioned before, there are different types of analysis are available using

OrCAD, in this laboratory, you will work through an example of each of the three

basic types of analysis.

• DC sweep :

1. Open OrCAD main window, Open a new project .

2. From the tool bar, click ʹ Place partʹ.

3. From source library, choose VDC "Dc source" and click ok. Place it on your

project page.

4. From Analog library, choose R "resistor" and click ok. Place two resistors on

the project page.

5. From tool bar, click ʹ Place wireʹ and connect between the components as

shown at figure(1).

6. From the tool bar, click ʹ Place groundʹ, choose ʹ 0/SOURCEʹ, connect it to the

circuit as shown at figure (1).

7. Save your project.

8. click PSpice, New simulation profile, Type your desired name of the

simulation name. Click OK.

9. Simulation Settings window will appear. Choose ʹ DC Sweep ʹ as the analysis

type.

10. Choose the type of the dc source you want to draw the output with respect to

it . At this example it is a voltage source. Type its name V1.

11. Type the range of V1, start value, final value and increment which is the step

between voltage values.


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Figure (1) : DC sweep example circuit

12. It is intended to plot the current versus to the value of voltage source, so the

current should be measured. Put ʹCurrent into Pinʹ as shown at figure (1)

13. click Runʹ. The result of simulation will appear as shown at figure(2).

Figure (2) : DC sweep simulation result

14. Try to analyze and explain the result, does it as you have predicted ….. ?!!

15. For any details, see ʹ Example1 ʹ video file on the aJached CD.

• AC sweep :

1. Try to follow the same steps at ʹExample1ʹ, to build the circuit shown at

figure(3).

2. The differences between two examples are:

- Use VAC ʺac sourceʺ source instead of VDC, change its value to 1V.

Ac source is used for plotting relations versus frequency.

- Use ʹVoltage levelʹ instead of ʹCurrent into Pinʹ, to plot the output

voltage versus frequency.

- Choose ʺAC Sweepʺ as an analysis type for this example, linear choice.

Type the range of frequency at start frequency, end frequency and

total points.

- Note that the x-axis variable is the frequency while at dc sweep is the

source voltage V1.

- The result of AC sweep simulation is shown at figure(4).


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Figure (3) : AC sweep example circuit

Figure (4) : AC sweep simulation result

• Time Transient :

1. Follow steps at ʹExample2 ʹ to build the circuit shown at figure(5).

2. The differences are:

- Use VSIN ʺsinusoidal sourceʺ source instead of VAC. The sinusoidal

source is used for plotting relations versus for time.

- Double click on the sinusoidal source to change its parameters:

frequency, amplitude and offset voltage.

- Choose ʺTime transientʺ as an analysis type for this example. Type the

duration of simulation you want. Keep it suitable with the frequency

of the sinusoidal input to get obvious simulation result.

- Note that the x-axis variable is the time.

- Showing the input and output signals in the simulation result helps

you during results analysis.

- The result of AC sweep simulation is shown at figure(6).


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Figure (5) : Time transient example circuit

Figure (6) : Time transient simulation result


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Laboratory Instruments and Measurements

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Objectives:

• To learn how to make basic electrical measurements of current, voltage, and

resistance using multi-meters.

• To be familiar with the bread board.

Theoretical Background:

Definitions:

a- Electric current (i or I) is the flow of electric charge from one point to another,

and it is defined as the rate of movement of charge past a point along a

conduction path through a circuit, or i = dq/dt. The unit for current is the

ampere (A). One ampere = one coulomb per second .

b. Electric voltage (v or V) is the "potential difference" between two points, and

it is defined as the work, or energy required, to move a charge of one

coulomb from one point to another. The unit for voltage is the volt (V). One

volt = one joule per coulomb.

c. Resistance (R) is the "constant of proportionality" when the voltage across a

circuit element is a linear function of the current through the circuit element,

or v = Ri. A circuit element which results in this linear response is called a

resistor. The unit for resistance is the Ohm(Ω . One Ohm = one volt per

ampere. The relationship v = Ri is called Ohm's Law.

Typical standard resistor values are 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6,

6.8, 7.5, 8.2, and 9.1 multiplied by a power of 10

d. Electric power (p or P) is dissipated in a resistor in the form of heat. The

amount of power is determined by p=Vi, p=i2R, or p=v2/R. The latter two

equations are derived by using Ohms Law (v = Ri) and making substitutions

into the first equation. The unit for power is the watt (W) One watt = one

joule per second.

Instruments and equipments that will be used in this lab:

1- Multimeter:

Meters are used to make measurements of the various physical variables in

an electrical circuit. These meters may be designed to measure only one variable


Lab Manual

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such as a voltmeter or an ammeter. Other meters called multimeters are

designed to measure several variables, typically voltage, current and resistance.

These multimeters have the capability of measuring a wide range of values for

each of these variables. Some multimeter operate on battery power and are

therefore easily portable, but need battery replacement. Others operate on A.C.

power.

The read-out, or display, of value being measured on the multimeter may be

of the digital type or the analog type. The digital type displays the measurement

in an easy to read form. The analog type has a pointer which moves in front of a

marked scale and must be read by visually interpolating between the scale

markings.

In this lab we will use a digital multimeter which is as shown in figure 1.

Figure (1) : The multimeter device

It consists of :

- Ammeter which is used to measure A.C or D.C current passing in a branch

and is connected in series with the circuit’s elements.

- Voltmeter for measuring the A.C or D.C voltage drop a cross any two point

in the circuit, and is connected in parallel.

- Ohmmeter for measuring the resistance, and is connected across the resistant.

2- Oscilloscope:

An oscilloscope (abbreviated sometimes as 'scope or O-scope) is a type of

electronic test instrument that allows signal voltages to be viewed, usually as

a two-dimensional graph which a potential differences plotted as a function

of time. Although an oscilloscope displays voltage on its vertical axis, any

other quantity that can be converted to a voltage can be displayed as well.

Oscilloscopes are commonly used when it is desired to observe the exact

wave shape of an electrical signal. In addition to the amplitude of the signal,

an oscilloscope can show distortion and measure frequency, time between

http://en.wikipedia.org/wiki/Electronic_test_instrument

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

http://en.wikipedia.org/wiki/Waveform

http://en.wikipedia.org/wiki/Waveform


Lab Manual

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two events (such as pulse width or pulse rise time), and relative timing of two

related signals. (figure2.2)

Figure (2) : Oscilloscope

3- Wattmeter

The wattmeter is an instrument for measuring the electric power in watts of

any given circuit. The traditional analog wattmeter is an electrodynamics

instrument. The device consists of a pair of fixed coils, known as current coils,

and a movable coil known as the potential coil.

The current coils connected in series with the circuit, while the potential coil

is connected in parallel.

A current flowing through the current coil generates an electromagnetic field

around the coil. The strength of this field is proportional to the line current

and in phase with it. The potential coil has, as a general rule, a high-value

resistor connected in series with it to reduce the current that flows through it.

The result of this arrangement is that on a dc circuit, thus conforming to the

equation W=VA or P=VI. (figure 3)

Figure (3) : Wattmeter

http://en.wikipedia.org/wiki/Electric_power

http://en.wikipedia.org/wiki/Watt

http://en.wikipedia.org/wiki/Electrical_network

http://en.wikipedia.org/wiki/Electrodynamic

http://en.wikipedia.org/wiki/Coil

http://en.wikipedia.org/wiki/Series_and_parallel_circuits

http://en.wikipedia.org/wiki/Series_and_parallel_circuits

http://en.wikipedia.org/wiki/Electromagnetic_field

http://en.wikipedia.org/wiki/Resistor

http://en.wikipedia.org/wiki/Resistor

http://en.wikipedia.org/wiki/Direct_current


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4- Bread Board:

A breadboard is used to make up temporary circuits for testing or to try out

an idea. No soldering is required so it is easy to change connections and

replace components. Parts will not be damaged so they will be available to re-

use afterwards.

This is in contrast to strip board and similar prototyping printed circuit

boards, which are used to build more permanent soldered prototypes, and

cannot easily be reused.

A typical small bread board is shown in figure below(figure 4), which is

suitable for testing a small circuit.

Figure (4) : The bread board

Connections on Breadboard

Breadboards have many tiny sockets (called ʹholesʹ) arranged on a 0.1ʺ grid. The

leads of most components can be pushed straight into the holes. ICs are inserted

across the central gap with their notch or dot to the left.

Wire links can be made with single-core plastic-coated wire of 0.6mm diameter (the

standard size). Stranded wire is not suitable because it will crumple when pushed

into a hole and it may damage the board if strands break off.

The diagram shows how the breadboard holes are connected:

The top and bottom rows are linked horizontally all the way across as shown in

figure (5), it is suggested to use the horizontal holes ; one for the positive power

supply and the other for ground also the lower horizontal holes may be used for a

negative power supply.

The other holes are linked vertically in blocks of 5 with no link across the centre.

Notice how there are separate blocks of connections to each pin of ICs.

http://en.wikipedia.org/wiki/Stripboard

http://en.wikipedia.org/wiki/Printed_circuit_board

http://en.wikipedia.org/wiki/Printed_circuit_board


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Figure (5) : bread board connections

On larger breadboards there may be a break halfway along the top and bottom

power supply rows. It is a good idea to link across the gap before you start to build a

circuit, otherwise you may forget and part of your circuit will have no power!

Lab Work:

Building a Circuit on Breadboard

1. Connect the circuit shown in figure (6) on the bread board.

2. Set the power supply output voltage to 10v.

3. Find the value of the current passing through the circuit and the voltage

across the resistor using multi-meter.

4. Record the value that you got in the table 1.

1k10V

A

V

Figure (6)

V(volt) I(mA)

Table (1)


Lab Manual

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Multistage Amplifier – Part 1 ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Objectives:

Investigate the multistage amplifier design using simple BJT amplifier circuit,

especially cascade and cascade connections practically and by simulation

Prelab:

Consider the circuit shown in figure 2 and using OrCAD Pspise:

1. Connect the first stage amplifier without AC input (only DC), then find and

plot 1st transistor Q-point (Ic and Vce).

2. Like one, find and plot the Q-point of the 2nd transistor.

3. Now connect the multistage circuit with sinusoidal input (50mV, 1 kHz).

4. Plot the input voltage, 1st stage output voltage, 2nd stage voltage. " Don't plot

the signals on the same graphs".

5. Let the output of the first stage on the emiJer (VE1), the second output on the

collector and then plot the input voltage, 1st stage output voltage, 2nd stage

voltage. " Don't plot the signals on the same graphs".

6. Let the output of the first stage on the emiJer (VE1), the second output on the

emiJer (VE2) and then plot the input voltage, 1st stage output voltage, 2nd

stage voltage. " Don't plot the signals on the same graphs".

7. Comment on your results at (4, 5, and 6).


The properties of BJT amplifiers can be summarized in table(1).

These basic amplifier stages can be combined by cascade connection or cascode

connection to create multistage amplifiers with better overall characteristics.

• Cascade connection :

In which each stage is coupled with the next by a capacitor. Figure (1) shows a

general model for a cascade multistage amplifier configuration.


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Emitter follower CC CE with RE Common emitter

0

0

C1

R1

V1

0

0

C1

R1

V1

R2

0

0

C1

R1

V1

Construction

Low Medium High Voltage gain

High High Low Input resistance

Low High High Output resistance

Table (1) : Properties of BJT amplifiers

Figure (1) : General model for a cascade multistage amplifier

The gain of multistage amplifier is the product of the individual gain stages. For the

generalized example in figure (1), the over all gain can be calculated as :

Av(total) = Av1 . Av2 . Av3 ----------------------- (1)

The input resistance of the multistage amplifier equals to the input resistance of the

first amplifier stage as following:

Rin(total) = Rin1 --------------------------------------- (2)

And the output resistance will be

Rout(total) = Rout3 --------------------------------------- (3)


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0

0

0

0

R1

10 k

R2

1k

R3

1k

R4

100

R5

10k

R6

1k

R7

1k R8

47

R9

1.8 k

C1

100u

C2

22u

C3

100uQ1

Q2N2222

Q2

Q2N2222

V1

15V

V2

These properties will help us to design a multistage amplifier that has high gain,

high input resistance and low output resistance by carefully combining the basic BJT

amplifier stages.

• Cascode connection :

In which the collector of the leading transistor is connected to the emitter of

the following transistor as shown at figure (3). The cascode connection offers

high gain, high stability, and high input impedance.

Lab Work:

For the circuit shown in figure (2) :

1. Evaluate the DC Q-point for each transistor.

2. Connect the multistage circuit, plot the output voltage using (50 mV, 1k Hz)

sinusoidal input. Then determine the voltage gain.

3. Let the output of the first stage on the emitter, plot the output voltage and

determine the voltage gain.

4. Let the output of the second stage on the emitter, plot the output voltage and


5. Comment on your result.

Figure (2) : Cascade multistage circuit


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Exercises :

1. Calculate the DC Q-points for each transistor shown in the circuit in

figure (2), assume that β =100

2. Derive Zin, Av, Zout for the circuit in figure (2).

3. Simulate the circuit shown at figure (2) and figure (3).

0

0

0

0

Vout

Vin

R1

22k

R2

10k

R3

1k

R4

470

R522k

R6

10k

C1

100u

C2

10u

C3

10u

C4

22u

Q2N2222

Q2N2222

V1

15 V

f =1kHz

Figure (3) : Cascode multistage circuit


Lab Manual

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Multistage Amplifier – Part 2 ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Objectives:

Investigate another types of the multistage amplifier design using simple BJT

amplifier circuit, which are current mirror connection and Darlington connection

practically and by simulation.


1. Current mirror connection:

A current mirror may be through of as an adjustable

current regulator. The current limit being easily set by

a single resistance. In this lab one of these circuits will

be built. Also exploring regulating properties and

experience some of its practical limitations. Current

mirror circuit is shown in figure (1).

Figure (1) : Current mirror

2. Darlington connection:

A very popular connection of two bipolar junction transistors for operation as one

transistor. The main feature of it is that the composite transistor acts as a single unit

with a current gain that is the product of the current gains of the individual

transistors, that:

βD = β1 * β2

where βD is the current gain of the Darlington circuit, β1 is the current gain of the

first transistor and β2 is the current gain of the second transistor. Basic circuit of th

Darlington transistor is shown in figure (2).


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Figure (2) : Darlington transistor

Lab Work:

Part 1: Current mirror:

- Measurement of βf :

First a quick assessment will be made of the degree of electrical match

between two BJTs which will be used in the current mirror circuit. Using the

circuit shown in figure (3), do the following procedure :

0

0

12V

Q1220 k

3.3 k0.1u

0VVdc

Figure (3) : βf test

1. Increase VDC from zero till you obtain VCE = 0.2 V, this value should be

regarded as VDC1. The value of VDC should then increase to obtain VCE =


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1.5 V. This value of VDC should be recorded as VDC2. Then the vale of βf can be obtained as:

2. Repeat the above procedure for Q2.

3. Comment on the degree of match in βf for the two transistors

- Operation of current mirror:

R10

500

714.9mV

12V

0

6.043V

0

470

0V

Q5

Q2N2222

7.345V330

Q6

Q2N2222

86.55mVQ3

Q2N2222

I

6.043V

R7

500Q4

Q2N2222

I

12.00V

R6

1000 R8

500

I RLI

R9

500

Figure (4) : current mirror circuit

1. Build the circuit shown in figure (4).

2. Calculate the value of IREF.

3. Let the load resistance equal to 1 kΩ, then measure Ie1 and Ie2. Are they

nearly equal? Are they nearly to Iref? Summarize your result in table(1).


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Calculated Iref Measured Iref Measured Ie1 Measured Ie2 Calculated Ie2

Table (1)

4. Let the load resistance equals to 2 kΩ and measure Ie2 and Vce2. Repeat the

measuring for RL = 3 kΩ and 13 kΩ. Record your results in table (2).

RL= 1 kΩ RL= 2 kΩ RL= 3 kΩ RL= 13 kΩ

Meas. Ie2 (mA)

Meas. Vce2 (V)

Table (2)

Part 2: Darlington transistor:

0

0

Vi

Vo

3.3 M

390

0.5 u

0.5 u

18V

Figure (5): Darlington emiJer follower circuit

6. Connect the circuit shown in figure (5).

7. Measure the dc bias voltages and currents.

8. Evaluate the measured DC Q-point for each transistor.

9. Plot the output voltage using (50 mV, 1k Hz) sinusoidal input. Then



Lab Manual

٢٤

Exercises :

1. Calculate the DC Q-points for each transistor shown in the circuit in

figure (5).

2. Derive Zin, Av, Zout, Ai for the circuit in figure (5).

3. Simulate all circuits of this laboratory experiment.

4. Comment on your results.

Note :

you can get the value of β and ri of your Darlington transistor from its data

sheet.


Lab Manual

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ــــــــــــــــــــــــــــــــــــــــــــــــــExperiment 3

AC analysis of JFET ــــــــــــــــــــــــــــــــــــــــــــــــــ

Objectives:

• Revise the dc analysis of JFET circuits.

• To bias the JFET.

• To understand JFET AC model.

• To make JFET amplification.

Pre-lab:

Referring to figure (1), design a common source configuration that has an operating

point ( IDQ = 4mA, and Vout = 10V).

Theoretical background :

Bipolar junction transistors have low input impedance, small high frequency gain

and are non linear when |VCE| < 0.2 V. The input impedance is naturally restricted

by the forward-biased base-emitter junction. There are always problems due to the

main charge carriers passing through the region where the majority carriers are of

opposite polarity.

The field effect transistor (JFET) overcomes some of the problems of the bipolar

junction transistor. JFETs come in two types : N- channel and P- channel.

The designation refers to the polarity of the majority charge carriers in the bar of

semiconductor that connects the drain terminal D to the source terminal S. Since the

channel is formed from a single polarity (unipolar) material, its resistance is a

function only of the geometry of the conducting volume and the conductivity of the

material. The JFET operates with all PN junctions reverse-biased so as to obtain a

high input impedance into the gate.

Common Source Configuration :

The common source configuration for a FET is similar to the common emitter bipolar

transistor configuration and is shown in figure(1). The common source amplifier can

provide both a voltage and current gain. Since the input resistance looking into the

gate is extremely large the current gain available from the FET amplifier can be large


Lab Manual

٢٦

but the voltage gain is generally inferior to that available from a bipolar device. The

source by-pass capacitor is connected to provide a low impedance path to ground for

high frequency components. As a result of presence of by-pass capacitor, AC signals

wi11 not cause a swing in the bias voltage.

Since the FET gate current is small we can make the approximations iD=is and

Vg=Vgs: the source is positive with respect to the gate for reverse bias.

Figure (1): Common source configuration

Note: Donʹt forward bias JFET gate, forward gate current larger than 50 mA will

burn out the JFET.

Lab Work:

Part 1: JFET Biasing:

1. Refer to figure (1) use VDD = 14V.

2. Operating point IDQ = 4mA and Vout = 10 V.

3. Set RG = 1M ohm (or 2M ohms).

4. Place Rd with the value calculating in the pre-lab to get the desired operating

point.

5. Adjust the value of Rs until it matches the calculated value.

6. Switch the power on and confirm the Q-point, try to tune Rs until IQis close

as possible to 4mA.

7. Summarize your measurements in table (1).


Lab Manual

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IDQ Vout VDSQ Rs RD

Table (1)

Part 2: JFET Amplification:

0

0

Vout

C1

10u

C2

10uRsource

Rg

Rs

Rd

14V

V1

Function Generator

Figure (2)

1. Refer to figure (2).

2. Apply AC sine wave from the function generator (100mV p-p at 1KHz).

3. Observe the input and output signal on the oscilloscope.

4. Vary the amplitude of AC input as shown in table (2).

5. Record the corresponding parameters using the voltmeter.

6. Plot the input and the output signal on the same paper.

7. Connect the RL = 10k and measure Av, Avs, Ro.

8. Shunt Rs with 10uF capacitor, put AC signal 100mV p-p and observe the

output voltage on the oscilloscope.


Lab Manual

٢٨

Vin(t) 1kHz (rms) Vg(t) Iout Vout(t) Ro=Vout/Iout Distortion Av Avs

0.5

1

2

3

4

5

Table (2)

Exercises:

1. For the circuit in figure (1), Find JFET power and compare your result with

data sheet.

2. For the circuit of figure (2), Does the output voltage increases or decreases

compared with first steps? Why?


Lab Manual

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ـــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Experiment 4

Frequency Response of BJT

ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Objectives:

To study the frequency response and bandwidth of the common emitter CE-BJT, the

common collector CC-BJT, and the common base CB-BJT amplifiers.


The frequency response is a representation of the system's response to sinusoidal

inputs at varying frequencies. The output of a linear system to a sinusoidal input is a

sinusoid of the same frequency but with a different magnitude and phase. It is

defined as the magnitude and phase differences between the input and output

sinusoids. It is the measure of any system's output spectrum in response to an input

signal.

The frequency response allows you to determine how the system responds at

different frequencies, finds the stability properties of the system and designs the

appropriate controllers for the system according to required specifications.

Bandwidth is typically measured in hertz, It is the difference between the upper and

lower cutoff frequencies of a filter, a communication channel, or a signal spectrum. In

case of a low-pass filter or baseband signal, the bandwidth is equal to its upper cutoff

frequency. The term baseband bandwidth refers to the upper cutoff frequency.

• Low frequency response of BJT amplifier :

The low cutoff frequency is determined by Cs is given by the relation:

CsRiRsfLs

)(2

1

+Π=

where Ri = R1 II R2 II β re

http://en.wikipedia.org/wiki/Frequency_spectrum

http://en.wikipedia.org/wiki/Hertz

http://en.wikipedia.org/wiki/Cutoff_frequencies

http://en.wikipedia.org/wiki/Communication_channel

http://en.wikipedia.org/wiki/Signal_spectrum

http://en.wikipedia.org/wiki/Lowpass

http://en.wikipedia.org/wiki/Baseband


Lab Manual

٣٠

The low cutoff frequency is determined by Cc is given by the relation :

CcRLRofLc

)(2

1

+Π=

where Ro = Rc II ro

The low cutoff frequency is determined by CE is given by the relation :

CcfLE

Re2

1

Π=

where re sR II\

+=

βRERe

Rs'=Rs ||R1||R2

• High frequency response of BJT amplifier :

iThiCRfHi

Π=

2

1

where RThi = Rs II R1 II R2 II Ri

Ri = R1||R2||Bre

Ci = Cwi + Cbe + CMi = Cwi + Cbe + (1 – Av )C bc

Re=15.76 ohm B=100

Av= ( -Rc||RL)/re

where RTho = Rc II RL II ro

Co = Cwo + Cce + CMo

oThoCRfHo

Π=

2

1


Lab Manual

٣١

Lab work :

1) Connect the circuit in figure 2.

2) Adjust the DC power supply at 20 V.

3) Adjust the function generator to sinusoidal of amplitude 1 V at a frequency at

1 kHz.

4) Measure the output voltage Vo.

5) Decrease the frequency till Vo = 0.707 Vo, Find fL.

6) Increase the frequency till Vo = 0.707 Vo, find fH.

7) Calculate the bandwidth (BW).

8) Vary the frequency according to table 1 and complete the table.

9) Plot the voltage gain against frequency.

10) Repeat above procedures for the circuit at figure 3 and complete table (2).

00

0

20 Vdc

0

R51k

C2 1u

C3

20u

R2

10 k

R1

47 k

R4

1k

Q1

Q2N2222

C1

10u

R3

3.3 k

V1

1 Vac

Figure (2) : Common Emitter amplifier


Lab Manual

٣٢

Av =Vo/Vi Vo (volt) Vi (volt ) Frequency (Hz)

1

10

100

1k

5k

10k

50k

100k

1M

Table (1) : CE results

0

0

00

20 Vdc

V1

1 Vac

R3

3.3 k

R4

1k

C2 1u

R5

4.7 k

C1

10u

R2

10 k

R1

47 k

Q1

Q2N2222

Figure (3) : Common Collector amplifier


Lab Manual

٣٣


1

10

100

1k

5k

10k

50k

100k

1M

Table (2) : CC results

Exercises :

1) Repeat all steps for figure 2 using OrCAD.

2) Repeat all steps for figure 3 using OrCAD.

3) Simulate the circuit at figure 4 to get its frequency response.

Figure (4) : Common Base amplifier


Lab Manual

٣٤

1

2 ( )LGsig i G

f CR Rπ=

+

1

2 ( )LCo L C

f CR Rπ=

+

1

2LSeq S

f CRπ=

Experiment 05

JFET Frequency Response

ــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Objectives:

• To analysis the FET amplifier in low & high frequencies to show and realize

the response.

• To find the cut off frequencies and calculate bandwidth.


1. Low frequency response- FET amplifier

The FET amplifier in low frequency is quite similar to that in BJT.

The low cutoff frequency is determined by CG is given by the relation:

The low cutoff frequency is determined by Cc is given by the relation :

The low cutoff frequency is determined by Cs is given by the relation :

Where

After calculation we choose the largest frequency as cutoff frequency.

Ri =RG Ro =RD Req=Rs //(1/gm)


Lab Manual

٣٥

1

2HiThi i

f CRπ=

1

2HoTho o

f CRπ=

0

0

V2

R2

1000k

R3

1k

C1

0.01u

C3

2u

C2

0.5u

R4

4.7k

V120V

R1

10k

J1

J2N3819R5

2.2kVs

Cc

RD

RsigRL

RG

RS

CsCG

Figure (1) :low frequency FET

2. High frequency response- FET amplifier

In high frequency there are parasitic capacitances (Cgd , Cgs , Cds) and wiring

capacitances (Cwi , Cwo) .

For the input circuit the high cutoff frequency is determined by the relation:

For the output circuit the high cutoff frequency is determined by the relation:

Where:

RTHI =Rsig//RG Ci =CWi + Cgs + CMi CMi=(1-Av ) Cgd Av=Vo/Vi= -gm(Rd//RL)

RTHo=RD//RL//rd Co=CWo +Cds +CMo CMO= (1-(1/Av))Cgd


Lab Manual

٣٦

0

0

R1

10k

R2

1000k

R3

1k

R4

4.7k

R5

2.2k

C1

0.01u

C2

0.5u

V120V

V2

C3

2u

J1

J2N3819C4

5p

C50.5p

C66p

C7

2p

C8

4p

Vs

Rsig CG

RGCwi

Cgs

Cgd

RD

RsCs

Cds

CcCc

Cwo

RL

Vo

Figure (2) : high frequency FET

Lab work :


2) Adjust the DC power supply at 20 V.

3) Adjust the function generator to sinusoidal of amplitude 1 V at a frequency at 1

kHz.

4) Measure the output voltage Vo.

5) Decrease the frequency till Vo = 0.707 Vo, Find fL.

6) Increase the frequency till Vo = 0.707 Vo, find fH.

7) Calculate the bandwidth (BW).

8) Vary the frequency according to table 1 and complete the table.

9) Plot the voltage gain against frequency.

10) Repeat above procedures for the circuit at figure 2 and complete table (2).


Lab Manual

٣٧


1

10

100

1k

5k

10k

50k

100k

1M

Table (1)


1

10

100

1k

5k

10k

50k

100k

1M

10M

15M

Table (2)


Lab Manual

٣٨

Exercises :

For figure1& figure2 :

1. calculate the cutoff frequencies using equations (mathematically)

2. Repeat all steps using ORCAD.

3. compare between result that you had got from exercise and compare

with result you had got from practical experience.


Lab Manual

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ــــــــــــــــــــــــــــــــــــــــــــــــــــــExperiment 6

Differential Amplifier ــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Objective:

In this laboratory experiment you will construct and test the differential amplifier

using BJTs.


The differential amplifier is a basic circuit, used in all linear integrated circuits. It is

also the basis for analog to digital and digital to analog converters. Understanding its

operation including the DC bias operation and its response to signal inputs are

important for further study of linear integrated circuits.. The differential mode gain

is Avdm and the common mode gain is Avcm. The differential amplifier circuit is

shown in figure (1).

0

0

00

1k

1k 1k

10k 10k

15V

15 V

Vin2Vin1

Figure (1) : Differential amplifier circuit

Lab Work:

1. Construct the circuit shown in figure (1). Make the circuit quiescent (no signal

applied) by connecting both bases to ground.

2. Measure DC values of Vc1, Vc2, VE, IB1, IB2 and IE.

3. Measure the differential gain (only one input used), from each input, and the

common-mode gain (both inputs connected to the same source) by applying


Lab Manual

٤٠

1kHz sinusoidal input voltages as shown in table (1). For each input

condition (1st – diff. mode, 2nd diff. mode, 3rd common mode).

4. Sketch all waveforms (Vin1, Vin2, Vc1 and Vc2) for each input condition; be

sure to include DC levels, peak to peak voltages, and relative phase

information.

Input condition Vin1

Vpp ∟0

Vin2

Vpp ∟0

Vc1

Vpp ∟0

Vc2

Vpp ∟0

1st – diff. mode 50 m 0 m ……. …….

2nd– diff. mode 0 m 50 m ……. …….

3rd -com. mode 50 m 50 m ……. …….

Table (1)

5. Using the measured data in table (1) calculate Avcm, Avdm and CMRR

6. Simulate the circuit shown in figure (1) via PSpice ( DC & AC analysis).

Compare the gain found via measurement and justify any possible

differences ( Vin =50 mV, 1KHz).

Remark : for realistic simulation, you need to create a Pspise model for your

Q2N2222 BJTs. To this end, click the BJT in your PSpise schematic to select it,

and then click Edit, PSpise model, add the line (+ βf = 100) and then save and

close.

7. Fill in the table (1) by simulation results also.

Exercises :

1. Calculate the DC Q-points for the transistors shown in the circuit in figure (1).

Assume that βf = 100.

2. For this circuit, evaluate Avcm, Avdm and CMRR.

3. Comment on your result.


Lab Manual

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ــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Experiment 7 & 8

Operational Amplifier

ــــــــــــــــــــــــــــــــــــــــــــــــــــــــ

Objective :

To study how to design and build a basic the Op-Amp used in inverting and non-

inverting amplifiers, inverting summing amplifier, integrator and differentiator.

Pre-lab :

1. Design an inverting amplifiers with gain -1 and -10 and input impedance of

least 1K. Use available resistor values.

2. Design non-inverting amplifiers with gain 1 and 10. Use available resistor

values.

- For part 1 and 2 , plot the voltage gain as a function of the frequency in

the range 0 to 50 kHz ( simulation).

3. Design a summing amplifier to implement the function Vo= - (V1+2V2).

- For part 3, generate the output voltage waveform if V1 as a sine wave or a

square wave of 2 volt peak and V2 is a DC voltage of 1 volt.

4. Design an integrator circuit so that when the input is a sine wave of

frequency 1 KHz, the output voltage has the same amplitude (unity gain ).

5. Design a differentiator circuit so that when the input is a sine of frequency 1

kHz, the output voltage has the same amplitude (unity gain).

- For part 4 and 5, generate the output voltage waveform if the input is a

sine wave or a square wave of 2 volt peak and of frequency 500 Hz, 1kHz,

and 2 kHz.


A basic model of an ideal operational amplifier is shown in figure (1). An op-amp is a

direct coupled device with differential inputs and a single ended output. The op-amp

responds only to the difference voltage between the two input terminals, not to their

common potential. A positive going signal at the inverting (-) input produces a


Lab Manual

٤٢

negative going signal at the output, whereas the same signal at the non-inverting (+)

input produces a positive going output. With a differential input voltage, Vin, the

output voltage , Vo will be Avo Vin, where Avo is the open loop gain of the op-amp.

Both input terminals of the op-amp will always be used, regardless of the

application. The output is single ended and is referred to ground. Bipolar (±) power

supplies are most commonly used, which allows both positive and negative output

voltages.

Properties that are useful in describing the operation of operational amplifiers are

listed below and the ideal values given. Figure (1) illustrates the relationships

between the op-amp and these properties.

1. The voltage gain is high – Ideal value Avo is = ∞ .

2. The input resistance is high – Ideal value Rin = ∞ .

3. The output resistance is low – ideal value Ro = 0 .

4. The bandwidth is high – ideal value BW = ∞ .

5. The CMRR – ideal value = ∞ .

Figure (1) : Equivalent circuit of an operational amplifier

From these ideal characteristics, we can deduce two very important additional

properties of the operational amplifier. Since the voltage gain approaches infinite,

any output signal developed will be the result of an infinitely small input signal.

Thus, in essence:

1. The differential input voltage is zero.

2. There is no current flow into either the inverting or the non-inverting signal

input terminal because of the infinite input resistance.

These two axioms will be used repeatedly in the analysis and design of circuits using

op-amps. Once these properties are understood, the operation of virtually any circuit


Lab Manual

٤٣

using an op-amp can be logically deduced. For the most real op-amps, these ideal

calculations are very close to the actual conditions.

Most linear op-amp circuits can be divided into two general classes; inverting and

non-inverting. Other circuits can be a combination of both. In the next two sections

we briefly review these two basic configurations.

1. Inverting configuration :

The basic inverting configuration is shown in figure (2). Because of the virtual

short and because the non-inverting terminal is grounded, we say that there is a

virtual ground at the inverting terminal. The final closed loop gain expression is :

The negative sign justifies the term " inverting" . In the more general case that

resistors are replaced by impedances.

Figure (2) : Basic inverting configuration

2. Non-inverting configuration :

The basic non-inverting configuration is shown in figure (3). The final closed loop

gain expression is :

Since the closed loop gain is positive, the term " non-inverting" is justified.

Vo

0

Vi

R1

LM741

3

2

6

+

-

OUT

Rf

Figure (3) : Basic non-inverting configuration


Lab Manual

٤٤

Voltage follower : a particularly simple version of the non-inverting circuit with

unity gain is the voltage follower shown at figure (4). The name "follower" is due

to the fact that the output voltage "follows" the input. Voltage followers are

widely used to provide buffering between high internal resistance sources and a

load.

Vo

Vi

LM741

3

2

6

+

-

OUT

Figure (4) : Voltage follower

3. Inverting summing amplifier :

By adding additional input resistors to the basic inverting circuit of figure (2). We

have the summing amplifier (inverting ) shown in figure (5) with three inputs.

The output voltage is given by :

If R1 = R2 = R3 = R , then ;

0

Vo

V1

V2

V3

LM741

3

2

6

+

-

OUT

R1 Rf

R2

R3

Figure (5) : Inverting summing amplifier

4. Inverting integrator :

Referring to the general inverting circuit of figure (2), if Zf is a capacitor and Z1 is

a resistor, then we have the inverting integrator of figure (6). Assuming that the

capacitor has zero voltage at t = 0, the output voltage is given by :


Lab Manual

٤٥

0

VoVi

LM741

3

2

6

+

-

OUT

C

R

Figure (6) : Inverting integrator

Integrators suffer from DC components in the input voltage. If the input voltage

has a non-zero average value "DC term", then when this term is integrated it

becomes a linear ramp which over time will saturate the op-amp. Furthermore,

small DC voltages and currents present at and between the inputs of the op-amps

(known as input offset voltages and currents) also get integrated and they could

over time saturate the op-amp.

Integrators are widely used in practice because their frequency response has low

pass characteristics, which tends to attenuate noise that may be present in the

input voltage that noise has predominantly high frequency content.

5. Inverting differentiator :

By reversing the resistor and the capacitor in the integrator, we get the inverting

differentiator shown in figure (7). The output voltage is given by :

0

VoVi

LM741

3

2

6

+

-

OUT

R

C

Figure (7) : Inverting differentiator


Lab Manual

٤٦

Lab Work :

Check the designs you have prepared in your pre-lab. Lab results should be included

in your report.

You will use lm741 op-amp in the lab. Figure (8) illustrates its pin diagram.

Figure (8) : Pin diagram of lm741 op-amp

Exercises:

Discuss and compare your lab results and simulation outputs.


Lab Manual

٤٧

( )% 100%

( )o

i

ac

dcPP

η = ×

0

0

0

Q1

Q2N3904

R1

20k

R2

100

C1

10uV1

V222VVcc Rc

Experiment 09

Power transistors


Objectives:

To learn about power amplifiers types and know the characteristics of each type.


Amplifier classes represents the amount the output various over one cycle of

operation for a full cycle of input signal (return to section 12.1 in your book).

Amplifier efficiency is defined as the ratio between input power to output power.

Power Amplifier may be classify to:

Class A Class B Class AB Class C Class D

3. Class A

The power into amplifier is provided by supply. Without input signal the dc current

drawn is the collector bias ICQ . Then the input power drawn from supply is:

The output power (ac power) is given by :

The efficiency is:

The maximum efficiency is equal to 25%

Pi(dc)=Vcc *ICQ

Po(ac)= VCE (rms) *Ic(rms) Po(ac)= I2c(rms)*Rc Po(ac)= V2CE (rms)/


Lab Manual

٤٨

( )% 100%

( )o

i

ac

dcPP

η = ×

0

0

0

0

R1

1C2

100u

C1

100u

Q1

Q2N3904D1

D1N4002

R7

68

R6

8

R5

1

R4

1k

R3

1

R2

68

V3

V2

22V

V1

22V

Q4

Q2N3905

ViViViRL

Figure (1) :series-fed Class A amplifier

4. Class B

Where Idc is the dc current drawn from power supplies

PQ is the dissipated power by each transistor

The efficiency is:

The maximum efficiency is equal to 78.5%

Idc= 2*I(p)/pi Pi(dc)= Vcc * Idc Po(ac)= V2L(rms)/RL

P2Q= Pi(dc) - Po(ac) PQ = 0.5* P2Q


Lab Manual

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Lab work :



kHz.

3) Using wattmeter measure the input power .

4) Using wattmeter measure the output power on Rc .

5) Calculate the efficiency and verify less than maximum efficiency.



kHz.

8) Using wattmeter measure the deliver power by the two power supply .

9) Using wattmeter measure the output power on RL.

10) Calculate the efficiency and verify less than maximum efficiency.

Exercises :

For figure1& figure2 :

1. calculate the efficiency using equations (mathematically)

2. Using ORCAD plot the output and determine VP_P and then calculate

the efficiency.

3. compare between result that you get in exercise and compare with

result you get from practical experience.


Lab Manual

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Experiment 10

SCR&TRIAC


Objectives:

• To familiar with dimmer circuit and SCR.

Silicon controlled rectifier (SCRs)

There are many devices in the SCR (thyristor) family including the power thyristor,

the gate turn-off thyristor (GTO), the field controlled thyristor (FCT), the triac, etc.

A thyristor consists of a 4-layer silicon wafer with 3 P-N junctions. It has two power

terminals, called the anode (A) and cathode (K), and a third control terminal called

the gate (G).

Thyristor has two state Forward biased state if the anode voltage is larger than

cathode voltage, else Reverse biased state.

From the above curve When we apply forward bias voltage a small current flow,

this current called Forward leakage current. Until we reach Forward Breakdown

Voltage the resistance of thyristor will be small and current will flow from anode

to cathode.


Lab Manual

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When we apply negative voltage reverse leakage current will flow. Until reverse

breakdown voltage thyristor will damage.

Methods of triggering a thyristor:

• High forward voltage

• High rate of rise of forward voltage, dV/dt.

• Excessive temperature.

• Positive current gate pulse: This is the normal way that a thyristor is brought

into conduction. The gate pulse must be of a suitable amplitude and duration,

depending on the size of the thyristor.(We are interested in this method)

It can be turned off only by reducing the anode current below holding current

(current which thyristor turn off when reach it).

TRIAC

The Triac is a member of the thyristor family. But unlike a thyristor which conducts

only in one direction (from anode to cathode) a triac can conduct in both directions.

Thus a triac is similar to two back to back (anti parallel) connected thyristosr but

with only three terminals. As in the case of a thyristor, the conduction of a triac is

initiated by injecting a current pulse into the gate terminal. The gate looses control

over conduction once the triac is turned on. The triac turns off only when the current

through the main terminals become zero.

Lab work :

1) Connect the circuits in the previous figures.

2) Using oscilloscope view the result.

3) Change the value of resistor R4 in and not the change record your result in

the below table.


Lab Manual

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4) Replace the SCR by triac

0

R3

1k

V1

X1

2N1595

C2

1n

R4

11600

The photo V average Delay angle=w*t R4

1K

2K

3K

4K

5K

6K

8K

10K

11.5K

Exercise :

1) Repeat the lab work steps using orcad simulation program.

lab manual - site.iugaza.edu.ps

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