349 28 Lab-manual Lab-manual Op Amp 3e LabManual

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Laboratory Manual for

OperationalAmplifiers and

Linear ICsThird Edition

David A. Bell Lambton College of Applied Arts and Technology,

Sarnia, Ontario, Canada

Operational Amplifiers & Linear Ics, 3/e David A. Bell

© Oxford University Press 2011



Preface

This laboratory manual is designed to support the theory explained in my

book Operational Amplifiers and Linear ICs. A total of twenty-one

laboratory investigations are offered involving the construction and

testing of circuits discussed in the text book.

Each investigation consists of:

. a title

. an introduction that briefly describes the investigation

. a list of required equipment and components

. circuit diagrams and connection diagrams

. a step-by-step procedure to be followed

. a laboratory record sheet for recording data

. an analysis section for processing the data

Each laboratory investigation can normally be completed within a two

hour period. The procedures contain some references to the textbook;

however, all necessary circuit and connection diagrams are provided in

the manual, so the investigations can be performed without using the

textbook.

David Bell.





Contents 1 Basic Op-amp Circuits

2 Op-amp Parameters

3 Direct Coupled Amplifiers

4 Summing and Difference Circuits

5 Instrumentation Amplifier

6 Capacitor Coupled Voltage Followers

7 Capacitor Coupled Amplifiers

8 Use of Single-Polarity Supplies

9 Amplifier Bandwidth and Compensation

10 Slew Rate Effects

11 Schmitt Trigger Circuits

12 Differentiation and Integration

13 Precision Rectification, Clipping, and Clamping

14 Astable and Monostable Multivibrators

15 Triangular Waveform Generator

16 Timer Astable and Monostable Circuits

17 Sinusoidal Oscillators

18 Low-Pass and High-Pass Filters

19 Band-Pass Filters

20 Series Voltage Regulators

21 Power Amplifier





Laboratory Investigation 1

BASIC OP-AMP CIRCUITS

Introduction

Three basic op-amp circuits are investigated: a voltage follower, a noninverting amplifier,and an inverting amplifier. Each circuit is tested with dc input voltages, and then with ac

inputs. The output voltage levels are measured, and the amplitude and phase relationships

between input and output are noted.

Equipment

Plus-minus DC Power Supply—(0 to ±30 V, 50 mA)DC Power Supply—(0 to 12 V, 50 mA)

Two DC Voltmeters

OscilloscopeSinusoidal Signal Generator—(1 kHz, ±5 V)

Circuit Board

Op-amp—741 or similar alternative

0.25 W resistors—(2 × 56 k Ω), 8.2 k Ω, 270 Ω, 150 Ω, (2 × 68 Ω)

Procedure 1 Voltage Follower

1-1 Connect an op-amp as a voltage follower as shown in Fig. 1-1. Connect the power

supply, dc voltage source, voltmeters, and oscilloscope, as illustrated.

1-2 Set the power supply voltage to ±12 V, and adjust the voltmeters as necessary tomonitor the op-amp dc input and output voltage levels.





Figure 1-1 Voltage follower circuit and connection diagram.

1-3 Adjust the input voltage to +1 V, +2 V, and +3 V in turn. In each case, record the

output voltage on the laboratory record sheet.

1-4 Repeat Procedure 1-3 using levels of –1 V, –2 V, and –3 V.

1-5 Disconnect the dc source, substitute the signal generator in its place, and apply a ±5

V, 1 kHz sinusoidal input signal. Adjust the oscilloscope to monitor the ac input

and output of the circuit.1-6 Measure the circuit ac output voltage and the input/output phase relationship.

1-7 Adjust the signal amplitude to ±2 V and ±3 V in turn, and measure the output ineach case. Record the results on the laboratory record sheet.

Procedure 2 Noninverting Amplifier

2-1 Connect an op-amp as a noninverting amplifier as shown in Fig. 1-2. Connect the

power supply, dc voltage source, voltmeters, and oscilloscope as illustrated.

2-2 Set the power supply voltage to ±12 V. Note that the resistors are R1 = 8.2 k Ω and R2 = 150 Ω, as in the first part of Example 1-3 in the text book.

2-3 Adjust the input voltage to +50 mV and 75 mV in turn. In each case, record the

output voltage on the laboratory record sheet, and calculate the voltage gain.2-4 Repeat Procedure 2-3 using input levels of –50 mV and –75 mV.

2-5 Disconnect the dc source, and substituting the signal generator in its place, apply a

±25 mV, 1 kHz sinusoidal input signal.

2-6 Record the circuit output voltage and the input/output phase relationship.

2-7 Adjust the input voltage to ±50 mV. Record the output amplitude and calculate the

voltage gain.





2-8 Change R3 to approximately 111 Ω (use two series-connected 56 Ω resistors), as in

the second part of Example 1-3 in the text book.

2-9 Repeat Procedure 2-7.

Figure 1-2 Noninverting amplifier circuit and connection diagram.

Procedure 3 Inverting Amplifier

3-1 Connect an op-amp as an inverting amplifier as shown in Fig. 1-3. Connect the

power supply, dc voltage source, voltmeters, and oscilloscope as illustrated.3-2 Set the power supply voltage to ±12 V. Note that the resistors are R1 = 8.2 k Ω and

R2 = 270 k Ω, as in the first part of Example 1-4 in the text book.

3-3 to 3-7 Repeat Procedure 2-3 through 2-7.

3-8 Change R2 to approximately 137 Ω (use two series-connected 68 Ω resistors), as in

the second part of Example 1-4 in the text book.






Figure 1-3 Inverting amplifier circuit and connection diagram.

Analysis

1 Discuss the voltage follower input and output voltage amplitudes and phase

relationships.

2 Discuss the noninverting amplifier input and output voltage amplitudes and phaserelationships. Compare the experimental results to the calculated values in Example

1-3 in the text book.

3 Discuss the inverting amplifier input and output voltage amplitudes and phaserelationships. Compare the experimental results to the calculated values in Example







OP-AMP PARAMETERS

Introduction

An op-amp is connected to function as an inverting amplifier with its input grounded.The output offset voltage is measured and the input offset voltage is calculated. With the

op-amp connected as a voltage follower, the process of output offset nulling is

investigated. The input bias current is determined by inserting a resistor in series with

each input terminal, in turn, and measuring the resultant output voltage change. Input andoutput voltage ranges are checked by increasing the amplitude of a sinusoidal input signal

until peak clipping occurs. The op-amp open-loop gain is determined by us of a modified

inverting amplifier circuit.

Equipment

Plus-minus DC Power Supply—(0 to ±30 V, 50 mA)

DC Power Supply—(0 to 12 V, 50 mA)

Two DC Voltmeters

OscilloscopeSinusoidal Signal Generator—(100 Hz, ±15 V)

Circuit Board

Op-amp—741 or similar alternative0.25 W resistors—10 Ω, 100 Ω, 1.5 k Ω, 5.6 k Ω, 10 k Ω, (2 × 100 k Ω), 1 MΩ

Potentiometer—10 k Ω

Procedure 1 Offset Voltage Measurement

1-1 Connect an op-amp as an inverting amplifier with the input grounded as shown in

Fig. 2-1. Connect the power supply and voltmeter as illustrated.

1-2 Set the power supply to ±12 V, record the measured output offset voltage on the

laboratory record sheet, and calculate the input offset voltage.1-3 Calculate the input offset voltage due to the specified maximum input bias current:

( I B(max) × 10 Ω). Compare this to the input offset voltage determined from the

measurements to check that it does not introduce a significant error.





Figure 2-1 Circuit and connection diagram for offset voltage measurement.

Procedure 2 Input Bias Current and Offset Currents

2-1 Connect a 741 op-amp as a voltage follower with a nulling potentiometer and the

input grounded as shown in Fig. 2-2. Connect the power supply and voltmeters asillustrated.

Figure 2-2 Circuit and connection diagram for offset nulling investigation.





2-2 Set the power supply voltage to ±12 V, and adjust the nulling potentiometer to give

zero output voltage. If the output cannot be completely nulled, record the V o level.

2-3 Switch off the supply, remove the grounding connection from the op-amp

noninverting input terminal, and reconnect it to ground via a 1 MΩ resistor.

2-4 Switch the supply on again, and note the change in output voltage ∆V o (from the V o

nulled level). Calculate the input bias current at the op-amp noninverting terminal.2-5 Switch off the supply, remove the connection from the op-amp inverting input to

the output, and reconnect it to the output via a 1 MΩ resistor. Ground the

noninverting input directly once again.2-6 Switch the supply on again, and note the change in output voltage ∆V o (from the

nulled level). Calculate the input bias current at the op-amp inverting input.

2-7 Calculate the input offset current.

Procedure 3 Input and Output Voltage Ranges

3-1 Connect an op-amp voltage follower circuit as in Fig. 2-3 using 100 k Ω

resistors inseries with each input terminal, as illustrated. Set the power supply voltage to ±9 V.

3-2 Connect a sinusoidal signal generator to the voltage follower input, and anoscilloscope to monitor the input and output as shown. Note that the oscilloscope is

connected right at the op-amp noninverting input terminal.

3-3 Apply a 100 Hz sine wave input and increase its amplitude until the outputwaveform peaks just begin to flatten.

Figure 2-3 Circuit and connection diagram for input voltage range investigation.





3-4 Measure the input wave positive and negative peak levels to determine the op-amp

input voltage range.

3-5 Reconnect the op-amp as an inverting amplifier as in Fig. 2-4 using R1 = 10 k Ω, R2

= 100 k Ω, and a ±9 V supply.

3-6 Apply a 100 Hz sine wave input and increase its amplitude until the output

waveform peaks just begin to flatten.3-7 Measure the output wave positive and negative peak levels to determine the op-amp

output voltage range.

Figure 2-4 Circuit and connection diagram for output voltage range investigation.

Procedure 4 Open-Loop Voltage Gain

4-1 Construct the op-amp circuit illustrated in Fig. 2-5 using the components shown.

Connect the ±12 V supply and voltmeters to monitor V o and V 3.

4-2 Adjust the dc voltage source at the circuit input to give an op-amp output of V o = –

10 V.

4-3 Record the V 3 voltage level, and calculate the op-amp differential input.

4-4 Calculate the op-amp open-loop voltage gain.





Figure 2-5 Circuit and connection diagram for determining the open-loop gain.

Analysis

1 Compare the measured input offset voltage to the specified input offset voltage forthe op-amp. Comment on the input offset voltage due to the maximum input bias

current.

2 Compare the measured input bias current and the measured input offset current tothe quantities specified for the op-amp. Calculate the maximum resistance value

that should be used at the input terminals of the op-amp.

3 Compare the measured input and output voltage ranges to the op-amp specifiedranges. Briefly explain the cause of the limits on the input and output voltage

swings.





4 Compare the experimentally determined open-loop voltage gain with the quantities

specified for the op-amp. Briefly explain the operation of the circuit in Fig. 2-5.






DIRECT COUPLED AMPLIFIERS

Introduction

Several direct-coupled noninverting and inverting amplifier circuits designed in examplesin the text book are investigated. Tests are performed to determine the input/output

voltage relationships and to check input and output impedances.

Equipment


OscilloscopeSinusoidal Signal Generator—(1 kHz, ±15 mV)

Circuit Board

Op-amp—741, LF353 (or alternatives with similar specifications)0.25 W resistors—100 Ω, (2 × 270 Ω), (3 × 1 k Ω), (2 × 15 k Ω), (2 × 18 k Ω), 47 k Ω,

(2 × 1 MΩ),

Capacitors—20 µF

Procedure 1 Direct-Coupled Noninverting Amplifier

1-1 Construct the 741 noninverting amplifier shown in Fig. 3-1 using the component

values determined in Example 3-3 in the text book. Connect the power supply,

signal generator, and oscilloscope as illustrated.

1-2 Set the power supply voltage to ±15 V, and adjust the signal generator to produce a±15 mV, 1 kHz sinusoidal input to the amplifier.

1-3 Measure the amplitudes of the input and output waveforms, record the measuredquantities on the laboratory record sheet, and calculate the amplifier closed-loop

voltage gain.

1-4 Connect a 1 MΩ resistor in series with the amplifier input. Check that the output

voltage is unaffected, to demonstrate that Zin >> 1 MΩ.1-5 Capacitor-couple a 100 Ω resistor in parallel with the op-amp output using a 20 µF

capacitor. Check that the output voltage is unaffected, to show that Zout << 100 Ω.

1-6 Construct the LF353 noninverting amplifier shown in Fig. 3-2 using the componentvalues determined in Example 3-4 in the text book. (Note that the pin connections

for the 353 are different from those for the 741.)1-7 Repeat Procedures 1-2 through 1-5.





Figure 3-1 Noninverting amplifier using a 741 op-amp.





Figure 3-2 Noninverting amplifier using an LF353 op-amp.

Procedure 2 Direct-Coupled Inverting Amplifier

2-1 Construct the 741 inverting amplifier shown in Fig. 3-3 using the component values

determined in Example 3-6 in the text book. Connect the power supply, signalgenerator, and oscilloscope as illustrated.

2-2 Set the power supply voltage to ±15 V, and adjust the signal generator to produce a

±2.5 V, 1 kHz sinusoidal output from the amplifier.

2-3 Measure and record the amplitude of the input waveform, and calculate theamplifier closed-loop voltage gain.

2-4 Connect a 1 k Ω resistor in series with the amplifier input. Note that the outputvoltage is halved, to show that Zin = R1.

2-5 Remove the series-connected resistor at the input and capacitor-couple a 100 Ω

resistor in parallel with the output using a 20 µF capacitor. Check that the output

voltage is unaffected, to show that Zout << 100 Ω.

2-6 Construct the LF353 noninverting amplifier shown in Fig. 3-4 using the component

values determined in Example 3-7 in the text book.

2-7 Repeat Procedures 2-2 and 2-3.





2-8 Connect an 18 k Ω resistor in series with the amplifier input. Note that the output

voltage is halved, to show that Zin = R1.


Figure 3-3 Inverting amplifier using an 741 op-amp.





Figure 3-4 Inverting amplifier using an LF353 op-amp.

Analysis

Compare the performance of each of the amplifiers investigated to the design objectivesin the appropriate text book examples.






SUMMING AND DIFFERENCE CIRCUITS

Introduction

A summing circuit and a difference amplifier are investigated, both designed in text bookexamples. In each case various input voltages are applied and the output is monitored tocheck the input/output relationships.

Equipment Plus-minus DC Power Supply—(0 to ±15 V, 50 mA)Three DC Power Supplies—(0 to 12 V, 50 mA)

Three DC Voltmeters

Circuit BoardOp-amp—741, LF353 (or alternatives with similar specifications)

0.25 W resistors—560 Ω, (3 × 1.8 k Ω), 18 k Ω, (2 × 27 k Ω), (2 × 1 MΩ)

Procedure 1 Direct-Coupled Summing Circuits

1-1 Construct the inverting summing circuit shown in Fig. 4-1, using a 741 op-amp and

the component values determined in Example 3-9 in the text book.1-2 Connect the power supply, adjustable dc voltage sources, and voltmeters, as

illustrated, and set the power supply to ±15 V.

1-3 Set V 1 and V 2 to the voltage levels shown for Procedure 1-3 on the laboratory recordsheet, and record the output voltages in each case.

1-4 Change R3 to 18 k Ω and repeat the process using the levels listed for Procedure 1-4

on the laboratory record sheet

Figure 4-1 Two-input inverting summing circuit.





Figure 4-2 Difference amplifier.

Procedure 2 Direct-Coupled Difference Amplifier

2-1 Construct the difference amplifier shown in Fig. 4-2 using an LF353 op-amp and

the component values determined in Example 3-10 in the text book.

1-2 Connect the power supply, adjustable dc voltage sources, and voltmeters, asillustrated, and set the power supply to ±15 V.

2-3 Set V 1 and V 2 to the voltage levels shown for Procedure 2-3 on the laboratory record

sheet, and record the output voltages in each case.2-4 Ground the two input terminals and connect an adjustable dc bias source (V B)

between R4 and ground, as illustrated in Fig. 4-3(a).

2-5 Investigate the adjustable dc bias source as a level shifter, recording its voltage

level and the resultant output voltage.2-6 Remove the dc source and voltmeter from R4, ground R4 once again. Connect the

two input terminals together and connect the adjustable dc source (as a common-mode input) to both inputs, as illustrated in Fig. 4-3(b).

2-7 Set the common mode input to 10 V, record the output voltage level, and calculate

the common mode gain.





Figure 4-3 Difference amplifier modifications to investigate output level shifting and common

mode gain.





Analysis

1 Use Eq. 3-10 in the text book to calculate the output voltage levels for each set of

inputs for the summing circuit. Compare the calculated and measured quantities.

2 Use Eq. 3-12 in the text book to calculate the output voltage levels for each set of

inputs for the difference amplifier. Compare the calculated and measured quantities.3 Discuss the measured common mode gain for the difference amplifier.






INSTRUMENTATION AMPLIFIER

Introduction

An instrumentation amplifier is constructed and tested. Common mode gain, differentialgain, common mode nulling, and output level shifting are all investigated. Each stage

gain is checked with various input voltages.

Equipment


Two DC Power Supplies—(0 to 12 V, 50 mA)Two DC Power Voltmeters—(0 to ±15 V)

Oscilloscope

Sinusoidal Signal Generator—(1 kHz, ±15 mV)Circuit Board

Op-amps—(3 × 741)

Resistors—(2 × 27 k Ω), (3 × 12 k Ω)

Potentiometers—350 Ω, 10 k Ω

Procedure 1 Common Mode Voltage Gain and Level Shifting

1-1 Construct the instrumentation amplifier circuit shown in Fig. 5-1 using a ±15 V

supply and the component values determined in Example 3-12 in the text book.

(Note the use of decoupling capacitors C 1 and C 2 to ensure circuit stability.)1-2 Set R2 and R7 for maximum resistance, and set the dc offset voltage (V B) to zero.

1-3 Temporarily disconnect R4 and R6 from the outputs of A1 and A2, connect themtogether, and apply a 5 V input. Adjust R7 to produce 0 V dc output from A3.

1-4 Disconnect the 5 V input from R4 and R6 and reconnect the resistors to A1 and A2

once again. Do not alter R7 or V B.

1-5 Ground the A1 and A2 noninverting inputs, and record the level of V o from A3.1-6 Adjust V B to +1 V, +2 V, and +3 V in turn, and record the A3 output voltage in each

case.

1-7 Adjust V B to set V o3 to zero, reversing the polarity of V B if necessary. Record thelevel of V B.

1-8 Apply a +5 V common mode input to the A1 and A2 noninverting inputs, and recordthe output voltage from each op-amp.





Figure 5-1 Instrumentation amplifier





Procedure 2 Differential Gain

2-1 Ground the A2 noninverting input terminal and apply +10 mV to the A1 input.

2-2 Adjust R2 until V o3 = 4 V. Record the op-amp output voltages (V o1, V o2, and V o3.).

2-3 Reverse the polarity of the A1 input voltage, and record V o1, V o2, and V o3.

2-4 Ground the A1 noninverting input terminal and apply +10 mV to the A2 input.Record V o1, V o2, and V o3.

2-5 Reverse the polarity of the A2 input voltage, and record V o1, V o2, and V o3.

2-6 Apply +5 mV to the A1 input and –5 mV to the A2 input and note the new levels ofV o1, V o2, and V o3.

2-7 Switch of the supply voltage, and disconnect R2 without altering its setting.

Measure and record the R2 resistance.

Figure 5-2 AC testing.

Procedure 3 AC Operation

3-1 Reconnect R2, ground R7 and the A2 input, and connect a sinusoidal signal generatorand oscilloscope as illustrated in Fig. 5-2.

3-2 Apply a 100 Hz, 10 mV peak sine wave input. Measure and record the peak outputvoltage from A1, A2, and A3.

Analysis

1 Compare the slew rate determined in Procedure 1-3 with that specified for a 741 op-

amp.





2 From the results of Procedure 1-8, Calculate the common mode gain for the circuit.

3 From the Procedure 2-2 and 2-3 results, calculate each stage gain and the overalldifferential gain. Compare these to the quantities in Example 3-12 in the text book.

4 Discuss the results of Procedures 2-4 through 2-6.

5 Compare the measured resistance of R2 with the calculated value in Example 3-12

in the text book.6 Determine the common mode rejection ratio for the circuit.

7 Explain the results of the ac measurements made in Procedure 3-2.






CAPACITOR COUPLED VOLTAGE

FOLLOWERS

Introduction

Two capacitor-coupled voltage follower circuits designed in examples in the text bookare constructed and tested. Both circuits are tested for operation at 1 kHz, then the lower

cutoff frequency is determined. The input impedances of the circuits are also

investigated.

Equipment


Oscilloscope

Sinusoidal Signal Generator—(10 Hz to 10 kHz)Circuit Board

Op-amp—741Resistors—3.9 k Ω, (2 × 68 k Ω), (2 × 120 k Ω), 1 MΩ

Capacitors—0.27 µF, (2 × 0.5 µF), 0.39 µF, 0.82 µF

Procedure 1 Capacitor Coupled Voltage Follower

1-1 Construct the capacitor coupled voltage follower circuit shown in Fig. 6-1 using thecomponent values determined in Example 4-1 in the text book. Connect the power

supply, signal generator, and oscilloscope as illustrated.1-2 Set the power supply voltage to ±15 V, and adjust the signal generator to produce a

±1 V, 1 kHz sinusoidal input to the amplifier. Record the output voltage amplitude

on the laboratory record sheet and calculate the voltage gain.

1-3 Maintaining the input voltage constant, reduce the signal frequency until vo ≈ 0.707

vi. Record the lower cutoff frequency ( f 1).

1-4 Return the signal frequency to 1 kHz. Connect a 120 k Ω in series with the amplifier

input. Check the effect on the output voltage and calculate Zin.

1-5 Remove the 120 k Ω resistor and replace C 2 with a 0.39 µF capacitor. RepeatProcedure 1-3.

Procedure 2 High Zin Capacitor Coupled Voltage Follower

2-1 Construct the high input impedance capacitor coupled voltage follower circuitshown in Fig. 6-2 using the component values determined in Example 4-3 in the

text book. Connect the power supply, signal generator, and oscilloscope as

illustrated.

2-2 Repeat Procedures 1-2 and 1-3.





2-3 Return the signal frequency to 1 kHz. Connect a 1 MΩ in series with the amplifier

input. Check that the output voltage is unaffected, to demonstrate that Z in >> 1 MΩ.

Figure 6-1 Capacitor coupled voltage follower.





Figure 6-2 High input impedance capacitor coupled voltage follower.

Analysis

1 Discuss the performance of each circuit in relation to the specified performance in

the design examples. Consider the effect of component tolerance on the lower

cutoff frequency.2 Explain the result of Procedure 1-5. Calculate the new capacitor values for the

circuit of Fig. 6-1 if C 1 is to set the lower cutoff frequency.

3 Briefly explain how capacitor C 2 in Fig. 6-2 affects the circuit input impedance.






CAPACITOR COUPLED AMPLIFIERS

Introduction

Three capacitor-coupled amplifier circuits are constructed and tested: a noninvertingamplifier, a high input impedance noninverting amplifier, and an inverting amplifier. All

three circuits are tested for voltage gain, input impedance, and lower cutoff frequency.

The upper cutoff frequency of the inverting amplifier is also investigated.

Equipment

Plus-minus DC Power Supply—(0 to ±15 V, 50 mA)Oscilloscope

Sinusoidal Signal Generator—(10 Hz to 10 kHz)

Circuit BoardOp-amp—741, LF353 (or alternatives with similar specifications)

Resistors—27Ω, 220 Ω, 270 Ω, 1 k Ω, 2.2 k Ω, 4.7 k Ω, 12 k Ω, 18 k Ω, 47 k Ω, 120 k Ω,

(3 × 1 MΩ)

Capacitors—680 pF, 0.1 µF, 0.12 µF, 0.18 µF, 0.68 µF, 75 µF, 180 µF

Procedure 1 Capacitor Coupled Noninverting Amplifier

1-1 Construct the capacitor coupled noninverting amplifier circuit shown in Fig. 7-1

using the component values determined in Example 3-3 and 4-4 in the text book.

Connect the power supply, signal generator, and oscilloscope as illustrated.





Figure 7-1 Capacitor coupled noninverting amplifier.

1-2 Set the power supply voltage to ±15 V, and adjust the signal generator to produce a±50 mV, 1 kHz sinusoidal input (vi) to the amplifier. Record the output voltage

amplitude (vo) on the laboratory record sheet and calculate the amplifier gain.

1-3 Maintaining the input voltage constant, reduce the signal frequency until vo approximately equals 0.707 of the vo level at f = 1 kHz. Record the lower cutoff

frequency ( f 1).

1-4 Return the signal frequency to 1 kHz. Connect a 120 k Ω in series with the amplifier

input. Check the effect on the output voltage and calculate Zin.

Procedure 2 High Zin Capacitor Coupled Noninverting Amplifier

2-1 Construct the noninverting amplifier circuit shown in Fig. 7-2 using the component

values determined in Example 4-5 in the text book. Connect the power supply,signal generator, and oscilloscope as illustrated. (It may be necessary to connect a

20 pF capacitor in parallel with R2 for circuit stability.)

2-2 Repeat Procedures 1-2 and 1-3 using a 15 mV signal amplitude.

2-3 Return the signal frequency to 1 kHz. Connect a 1 MΩ in series with the amplifier

input. Check that the output voltage is unaffected, to demonstrate that Z in >> 1 MΩ.





Figure 7-2 High input impedance capacitor coupled noninverting amplifier.

Procedure 3 Capacitor Coupled Inverting Amplifier

3-1 Construct the inverting amplifier circuit shown in Fig. 7-3 using the component

values determined in Examples 3-6 and 4-6 in the text book. Connect the power

supply, signal generator, and oscilloscope as illustrated.

3-2 Repeat Procedures 1-2 and 1-3.3-3 Still maintaining the input voltage constant, increase the signal frequency until vo

approximately equals 0.707 of the vo level at f = 1 kHz. Record the upper cutofffrequency ( f 2).

3-4 Return the signal frequency to 100 Hz. Connect a 1 k Ω in series with the amplifier

input. Check the effect on the output voltage and calculate Z in.





Figure 7-3 Capacitor coupled inverting amplifier.

Analysis

1 Discuss the performance of each of the noninverting amplifiers in relation to thespecified performance in the design examples. Consider the effect of component

tolerance on the lower cutoff frequency.

2 Calculate the new capacitor values for the circuit of Fig. 7-1 if C 1 is to set the lower

cutoff frequency.





3 Discuss the result of Procedure 2-3. Briefly explain how capacitor C 2 in Fig. 7-2

affects the circuit input impedance.

4 Discuss the performance of the inverting amplifier in relation to the specified

performance in the design examples.






USE OF SINGE-POLARITY SUPPLIES

Introduction

An inverting and a noninverting amplifier, both using single-polarity supply voltages, aretested for voltage gain and frequency response. The effect of input bias voltage change is

also investigated.

Equipment

Plus-minus DC Power Supply—(0 to 30 V, 50 mA)

OscilloscopeSinusoidal Signal Generator—(10 Hz to 10 kHz)

Circuit Board

Op-amp—741Resistors—250Ω, 1 k Ω, 5.6 k Ω, 47 k Ω, (3 × 100 k Ω), (3 × 220 k Ω)

Capacitors—680 pF, 0.2 µF, 2.2 µF, 3.9 µF, 75 µF, 180 µF

Procedure 1 Inverting Amplifier

1-1 Construct the inverting amplifier circuit shown in Fig. 8-1 using the componentvalues determined in Example 3-6 and 4-6 in the text book. Use a +30 V supply and

R3 = R4 = 100 k Ω.

1-2 Connect the signal generator, and oscilloscope as illustrated.





Figure 8-1 Inverting amplifier circuit using a single-polarity supply.

1-3 Adjust the signal generator to produce a ±50 mV, 1 kHz sinusoidal input (vi) to the

amplifier. Record the output voltage amplitude (vo) on the laboratory record sheetand calculate the amplifier gain.





1-4 Maintaining the input voltage constant, reduce the signal frequency until vo

approximately equals 0.707 of the vo level at f = 1 kHz. Record the lower cutofffrequency ( f 1).

1-5 Still maintaining the input voltage constant, increase the signal frequency until vo

approximately equals 0.707 of the vo level at f = 1 kHz. Record the upper cutoff

frequency ( f 2).1-6 Set the signal voltage to zero, then use the oscilloscope to measure the dc voltage

level at the junction of R3 and R4 and at the op-amp output.

1-7 Connect another 100 k Ω resistor in parallel with R4 to alter the bias voltage at theop-amp noninverting input terminal.


1-9 Repeat procedure 1-3.

Procedure 2 High Zin Capacitor Coupled Noninverting Amplifier

2-1 Construct the noninverting amplifier circuit shown in Fig. 8-2 using the component

values determined in Example 4-7 in the text book. Use a +24 V supply.2-2 Connect the signal generator, and oscilloscope as illustrated.

2-3 Apply a 1 kHz sinusoidal input and adjust its amplitude to give a 5 V peak output.Record the input voltage amplitude (vi) on the laboratory record sheet and calculate

the amplifier gain.





Figure 8-2 Noninverting amplifier circuit using a single-polarity supply.





2-4 Maintaining the input voltage constant, reduce the signal frequency until vo

approximately equals 0.707 of the vo level at f = 1 kHz. Record the lower cutofffrequency ( f 1).

2-5 Set the signal voltage to zero, then use the oscilloscope to measure the dc voltage

level at the junction of R1 and R2 and at the op-amp output.

2-6 Connect another 220 k Ω

resistor in parallel with R2 to alter the bias voltage at theop-amp noninverting input terminal.


2-8 Repeat procedure 2-3.

Analysis

1 Discuss the voltage gain and cutoff frequencies for the inverting amplifier in

relation to the specified performance in the design examples.

2 Comment on the dc level measurements made for Procedures 1-5 through 1-8, and

on the effect of changing the bias voltage.3 Discuss the voltage gain and cutoff frequencies for the noninverting amplifier in

relation to the specified performance in the design examples.4 Comment on the dc level measurements made for Procedures 2-5 through 2-7, and

on the effect of changing the bias voltage.






AMPLIFIER BANDWIDTH AND

COMPENSATION

Introduction

Three inverting amplifiers using three different op-amps are investigated for voltage gainand bandwidth.

Equipment


OscilloscopeSinusoidal Signal Generator—(100 Hz to 1 MHz)

Circuit Board

Op-amps—LM 108, 741, LF353 (or alternatives with similar specifications)Resistors—(2 × 1 k Ω), 100 k Ω

Capacitors—3 pF, 30 pF

Procedure 1 Bandwidth of an Amplifier Using an LM108

1-1 Construct the inverting amplifier circuit shown in Fig. 9-1. Use a ±15 V supply, and

connect the signal generator, power supply, and oscilloscope as illustrated.





Figure 9-1 Inverting amplifier circuit using an LM108 op-amp.

1-2 Adjust the signal generator to produce a 1 kHz sinusoidal input and adjust it to give

a 100 mV peak output. Record the input voltage amplitude on the laboratory recordsheet and calculate the amplifier gain.

1-3 Maintaining the input voltage constant, increase the signal frequency until vo

approximately equals 0.707 of the vo level at f = 1 kHz. Record the upper cutofffrequency ( f 2).

1-4 Change C f to 30 pF and repeat procedures 1-2 and 1-3.

Procedure 2 Bandwidth of an Amplifier Using a 741

2-1 Replace the LM108 in Fig. 9-1(b) with a 741, and remove capacitor C f .

2-2 Repeat procedures 1-2 and 1-3.

2-3 Change resistor R2 to 47 k Ω, and repeat procedures 1-3 and 1-4 once again.

Procedure 3 Bandwidth of an Amplifier Using an LF353

3-1 Construct the inverting amplifier circuit shown in Fig. 9-2. Use a ±15 V supply, and


3-2 Repeat procedures 1-2 and 1-3.





Figure 9-2 Inverting amplifier using an LF353 op-amp.

Analysis

1 Comment on the measured mid-frequency voltage gains for all three amplifiers.2 Compare the LM108 circuit upper cutoff frequencies measured for Procedures 1-2

and 1-4 with those determined in Example 5-5 in the text book.

3 Referring to Fig. 5-9 in the text book, estimate the cutoff frequencies for the 741

op-amp circuit for ACL = –100 and for ACL = –47. Compare to the measured resultsfor Procedures 2-2 and 2-3.

4 Using the LF353 circuit cutoff frequency determined for Procedure 3-3, calculate

the op-amp GBW, and compare it to the specified GBW for an LF353.






SLEW RATE EFFECTS

Introduction

A 741 voltage follower is constructed and tested to determine slew rate, small signalcutoff frequency, and slew rate limited cutoff frequency. Two noninverting amplifier, one

using a 741 and one using a 353, are constructed and tested for the same quantities.

Equipment


OscilloscopeFunction Generator (sine and square wave)—(100 Hz to 1 MHz)

Circuit Board

Op-amps—LM 108, 741, LF353 (or alternatives with similar specifications)Resistors—(2 × 1 k Ω), (2 × 10 k Ω), 47 k Ω, (2 × 100 k Ω), 1 MΩ

Procedure 1 Slew Rate Effects on a 741 Voltage Follower

1-1 Construct the inverting amplifier circuit shown in Fig. 10-1. Use a ±15 V supply,

and connect the signal generator, power supply, and oscilloscope as illustrated.

Figure 10-1 Voltage follower circuit using a 741 op-amp.

1-2 Adjust the signal generator to produce a 10 kHz, ±5 V square wave.





1-3 Measure the rise time (t r ) of the circuit output waveform. Record t r on the laboratory

record sheet, and calculate the slew rate.

1-4 Replace the square wave with a 1 kHz sinusoidal wave, and adjust the sine wave

amplitude to give a 100 mV peak-to-peak output.

1-5 Maintaining the input voltage constant, increase the signal frequency until vo equals

70.7 mV p-to-p at the circuit upper cutoff frequency ( f 2). Record f 2.1-6 Reset the signal frequency to 1 kHz, and adjust the sine wave amplitude to give a

±5 V output.

1-7 Maintaining the input voltage constant, increase the signal frequency until vo falls to±(0.707 × 5 V) at the slew rate limited cutoff frequency ( f S). Record f S.

Figure 10-2 Noninverting amplifier using a 741 op-amp.

Procedure 2 Slew Rate Effects on a 741 Noninverting Amplifier

2-1 Construct the 741 noninverting amplifier circuit shown in Fig. 10-2. Use a ±15 Vsupply, and connect the signal generator, power supply, and oscilloscope as

illustrated.





2-2 Apply a 5 kHz square wave input, and adjust its amplitude to produce a ±5 V circuit

output.


record sheet, and calculate the slew rate.

2-4 Replace the square wave with a 1 kHz sinusoidal wave, and adjust the sine wave

amplitude to give a 100 mV p-to-p output.2-5 Maintaining the input voltage constant, increase the signal frequency until vo equals

70.7 mV p-to-p at the circuit upper cutoff frequency ( f 2). Record f 2.

2-6 Reset the signal frequency to 1 kHz, and adjust the sine wave amplitude to give a±10 V output.

2-7 Maintaining the input voltage constant, increase the signal frequency until vo falls to

±7.07 V at the slew rate limited cutoff frequency ( f S). Record f S.

2-2 Change resistor R2 to 47 k Ω, and repeat procedures 2-4 through 2-7.

Figure 10-3 Noninverting amplifier using an LF353 op-amp.





Procedure 3 Slew Rate Effects on an LF353 Noninverting Amplifier

3-1 Construct the LF353 noninverting amplifier circuit shown in Fig. 10-3. Use a ±15 V

supply, and connect the signal generator, power supply, and oscilloscope as

illustrated.

3-2 Apply a 100 kHz square wave input, and adjust its amplitude to produce a ±5 Vcircuit output.


record sheet, and calculate the slew rate.3-4 Replace the square wave with a 1 kHz sinusoidal wave, and adjust the sine wave

amplitude to give a 100 mV p-to-p output.

3-5 Maintaining the input voltage constant, increase the signal frequency until vo equals70.7 mV p-to-p at the circuit upper cutoff frequency ( f 2). Record f 2.

2-6 Reset the signal frequency to 1 kHz, and adjust the sine wave amplitude to give a

±10 V output.

2-7 Maintaining the input voltage constant, increase the signal frequency until vo falls to

±7.07 V at the slew rate limited cutoff frequency ( f S). Record f S.

Analysis

1 Compare the slew rate determined in Procedure 1-3 with that specified for a 741 op-

amp.

2 Estimate the cutoff frequency for a 741 small signal voltage follower, and compareit to the f 2 measured in Procedure 1-5.

3 Calculate the slew rate limited cutoff frequency for the 741 voltage follower with a±5 V output, and compare it to the measured result for Procedure 1-7.

4 Compare the slew rate determined in Procedure 2-3 with that from Procedure 1-3.

5 Estimate the cutoff frequency for the 741 noninverting amplifier fromgain/frequency response Fig. 5-9 in the text book. Compare it to the cutoff

frequency determined in Procedure 2-5.

6 Calculate the slew rate limited cutoff frequency for the 741 noninverting amplifier

with a ±10 V output, and compare it to the measured result for Procedure 2-7.7 Discuss the f 2 and f S frequencies measured in Procedure 2-9.

8 Compare the slew rate determined in Procedure 3-3 with that specified for an

LF353 op-amp.9 Estimate the cutoff frequency for the LF353 noninverting amplifier from GBW

specified on the op-amp data sheet. Compare it to the cutoff frequency determined

in Procedure 3-5.

10 Calculate the slew rate limited cutoff frequency for the LF353 noninverting

amplifier with a ±10 V output, and compare it to the measured result for Procedure

2-7.






SCHMITT TRIGGER CIRCUITS

Introduction

An inverting Schmitt trigger circuit is constructed and tested for upper and lower trigger

points, and the output waveform is investigated. The circuit is modified by including a

diode, then tested once again. A noninverting Schmitt trigger circuit is constructed and

similarly investigated.

Equipment


Oscilloscope

Function Generator (sine and triangular wave)—(1 kHz, ±8 V)Circuit Board

Op-amps—741

Resistors—39 k Ω, 56 k Ω, 150 k Ω, 180 k Ω, 220 k Ω

Diodes—(2 × 1N914)

Procedure 1 Inverting Schmitt Trigger

1-1 Construct the inverting Schmitt trigger circuit shown in Fig. 11-1(a) and (b) using

the component values determine in Example 8-3 in the text book. Use a ±15 V

supply, and connect the signal generator, power supply, and oscilloscope asillustrated.

1-2 Adjust the signal generator to produce a 1 kHz, ±5 V triangular wave input.

1-3 Sketch the input and output waveforms on the laboratory record sheet, and record

the upper and lower trigger point voltages.

1-4 Adjust the amplitude of the input waveforms to ±6 V and ±5 V in turn. Measure and

record the trigger point voltages in each case.1-5 Change the input to a 1 kHz, ±5 V sinusoidal waveform. Once again sketch the

input and output waveforms, and record the trigger voltages.

1-6 Modify the input by including diode D1 in series with R1, as in Fig 11-1(c).

1-7 Repeat Procedures 1-2 through 1-4.





Figure 11-1 Inverting Schmitt trigger circuit.





Figure 11-2 Noninverting Schmitt trigger circuit.





Procedure 2 Noninverting Schmitt Trigger Circuit.

2-1 Construct the noninverting Schmitt trigger circuit shown in Fig. 11-2 using the

component values from Fig. 8-15(b) in the text book. Use a ±15 V supply, and


2-2 Adjust the signal generator to produce a 1 kHz, ±7 V triangular wave input.2-3 Sketch the input and output waveforms on the laboratory record sheet, and record

the upper and lower trigger point voltages.

2-4 Adjust the amplitude of the input waveforms to ±8 V and ±6 V in turn. Measure andrecord the trigger point voltages in each case.

2-5 Change the input to a 1 kHz, ±7 V sinusoidal waveform. Once again sketch the

input and output waveforms, and record the trigger voltages.

Analysis

1 Compare the upper and lower trigger point voltages measured in Procedures 1-3through 1-5 to the triggering levels used in Example 8-3 in the text book.

2 Discuss the shape of the output waveforms obtained for Procedures 1-3 and 1-5.3 Discuss the output waveforms and triggering voltages obtained for Procedure 1-7.

4 Compare the upper and lower trigger point voltages measured in Procedures 2-3

through 2-5 with the triggering levels determined in Example 8-4 in the text book.5 Discuss the shape of the output waveforms obtained for Procedures 2-3 through 2-5.






DIFFERENTIATION AND INTEGRATION

Introduction

Differentiating and integrating circuits are constructed and tested for response to variousinput waveforms. The circuits use component values determined in Examples in the text

book, so that their performances may be compared to the expected performances.

Equipment


OscilloscopeTriangular Wave Generator—(5 kHz, ±0.5 V)

Square Wave Generator—(100 Hz to 500 Hz, ±0.5 to ±5 V)

Sinusoidal Wave Generator—(100 Hz to 500 Hz, ±0.5)Circuit Board

Op-amps—741, LF353 (or alternatives with similar specifications)

Resistors—470Ω, (2 × 10 k Ω), (2 × 12 k Ω), 270 k Ω

Capacitors—0.05 µF, 0.1 µF

Procedure 1 Differentiating Circuit

1-1 Construct the differentiating circuit shown in Fig. 12-1 using the component values

determine in Example 8-7 in the text book. Use a ±15 V supply, and connect the

signal generator, power supply, and oscilloscope as illustrated.1-2 Adjust the signal generator to produce a 5 kHz, ±0.5 V triangular wave input.

1-3 Sketch the input and output waveforms on the laboratory record sheet, and recordthe positive and negative peak voltage levels.

1-4 Replace the triangular wave input with a 100 Hz, ±0.5 V square wave.


the positive and negative peak voltage levels. If possible, alter the rise and fall timesof the square wave input and note the effect on the output.

1-6 Replace the square wave input with a 100 Hz, ±0.5 V sine wave.

1-7 Observe the input and output waveforms and note the phase relationship.

1-8 Slowly increase the sine wave frequency to discover the approximate frequency that

causes the output to shift by 3° from the correctly differentiated output wave.





Figure 12-1 Differentiating circuit.

Figure 12-2 Integrating circuit.





Procedure 2 Integrating Circuit.

2-1 Construct the integrating circuit shown in Fig. 12-2 using the component values

determined in Example 8-9 in the text book. Use a ±15 V supply, and connect the

signal generator, power supply, and oscilloscope as illustrated.

2-2 Adjust the signal generator to produce a 500 Hz, ±5 V square wave input.2-3 Sketch the input and output waveforms on the laboratory record sheet, and record

the positive and negative peak voltage levels.

2-4 Replace the square wave input with a 500 Hz, ±0.5 V sinusoidal wave.2-5 Observe the input and output waveforms and note the phase relationship.

2-6 Slowly reduce the sine wave frequency to discover the approximate frequency that

causes the output to shift by 3° from the correctly differentiated output wave

Analysis

1 Compare the waveforms obtained for Procedures 1-3 to the waveforms in Fig. 8-25(a) in the text book.

2 Compare the waveforms obtained for Procedures 1-5 to the waveforms in Fig. 8-25(b) and (c) in the text book.

3 Comment on the input-output sine wave phase relationship observed for Procedure

1-7, and on the maximum differentiating frequency determined for Procedure 1-8.4 Compare the waveforms obtained for Procedures 2-3 to the waveforms in Fig. 8-31

in the text book. Compare the peak output voltage levels to the design levels in

Example 8-8 in the text book.

5 Comment on the input-output sine wave phase relationship observed for Procedure

2-5, and on the minimum integrating frequency determined for Procedure 2-6.






PRECISION RECTIFICATION, CLIPPING,

AND CLAMPING

Introduction

Saturating and nonsaturating precision half-wave rectifier circuits are constructed andtested. A precision clipping circuit with an adjustable clipping level is investigated, and a

precision clamping circuit is tested for response to square wave inputs.

Equipment

Plus-minus DC Power Supply—(0 to ±15 V, 50 mA)Oscilloscope

Sinusoidal Wave Generator—(1 kHz, ±15 mV)

Square Wave Generator—(10 kHz, ±5 V)Circuit Board

Op-amps—741, LF353 (or alternatives with similar specifications)Resistors—(2 × 470 Ω), 820 Ω, 1 k Ω, 1.5 k Ω, 2.2 k Ω, 3.9 k Ω, (2 × 22 k Ω)

Capacitors—200 pF, 5000 pF, 0.5 µF


Diodes—(2 × 1N914)Zener Diodes—(2 × 1N749)

Procedure 1 Precision Half-wave Rectifiers

1-1 Construct the saturating precision rectifier circuit shown in Fig. 13-1. Use a ±15 Vsupply, and connect the sinusoidal signal generator, power supply, and oscilloscope

as illustrated.

1-2 Adjust the signal generator to produce a 100 Hz, ±2 V sinusoidal wave input.Observe the half-wave rectified output waveform, and record its peak amplitude.

1-3 Switch the dc supply off, reverse the diode polarity, then switch the supply on

again.

1-4 Repeat procedure 1-2.1-5 Increase the signal frequency until the output becomes distorted. Record the

frequency at which the rectifier circuit is still operating satisfactorily.

1-6 Construct the nonsaturating precision rectifier circuit shown in Fig. 13-2 using thecomponent values determined in Example 9-1 in the text book. Use a ±15 V supply,

and connect the sinusoidal signal generator, power supply, and oscilloscope as

illustrated.


1-8 Switch the dc supply off, reverse the polarity of both diodes, then switch the supply

on again.







Figure 13-1 Saturating precision half-wave rectifier circuit.

Figure 13-2 Nonsaturating precision half-wave rectifier circuit.





Procedure 2 Clipping Circuit.

2-1 Construct the clipping circuit shown in Fig. 13-3 using the component values

determined in Example 9-4 in the text book. Use a ±15 V supply, and connect the

signal generator, power supply, and oscilloscope as illustrated.

2-2 Adjust the signal generator to produce a 1 kHz, ±7 V sine wave input.2-3 Observing the output waveform on the oscilloscope, slowly adjust the moving

contact of R4 from one extreme to the other. Measure and record the clipped output

voltage peaks at each extreme.

Figure 13-3 Adjustable clipping circuit.





Figure 13-4 Clamping circuit.

Procedure 3 Precision Clamping Circuit.

3-1 Construct the clamping circuit shown in Fig. 13-4 using the component valuesdetermined in Example 9-7 in the text book. Use a ±12 V supply, and connect the

signal generator, power supply, and oscilloscope as illustrated.3-2 Adjust the signal generator to produce a 10 kHz, ±5 V square wave input. Measure

and record the peak-to-peak output voltage, and note the positive peak relationshipto ground level.

3-3 Switch the supply off, reverse the polarity of the diodes and of capacitor C 1.

3-4 Switch the supply on again, and repeat Procedure 3-2.

Analysis

1 Comment on the results of Procedures 1-2 through 1-8. How might the performance

of the saturating and nonsaturating circuits differ at high frequencies?2 Compare the results of Procedure 2-3 with the clipping range specified in Example

9-4. Show how the clipping circuit should be modified to clip off an adjustable

portion of the positive half-cycle while reproducing the complete negative half-

cycle.3 Comment on the input-output sine wave phase relationship observed for Procedure

1-7, and on the maximum differentiating frequency determined for Procedure 1-8.





4 Comment on the results of Procedures 3-2 and 3-4. Explain how the clamping

circuit should be modified to clamp the output peaks at voltage levels above or below ground.






ASTABLE AND MONOSTABLE

MULTIVIBRATORS

Introduction

An astable multivibrator and a monostable multivibrator designed in examples in the text book are constructed and tested. The output frequency of the astable is measured for

comparison to the design frequency, and its capacitance value is altered to observe the

resultant frequency change. The pulse width of the monostable output is measured, andits capacitance value is altered to investigate its effect on the pulse width.

Equipment


OscilloscopePulse Generator—(100 µs, 200 Hz, 2 V)

Circuit BoardOp-amp—LF353 (or alternative with similar specifications)

Resistors—3.3 k Ω, 39 k Ω, 56 k Ω, 1 MΩ

Capacitors—1100 pF, (2 × 0.1 µF)

Diode—1N914

Procedure 1 Astable Multivibrator

1-1 Construct the astable multivibrator circuit shown in Fig. 14-1, using the componentvalues determined in Example 10-1 in the text book. Use a ±10 V supply, andconnect the power supply, and oscilloscope as illustrated.

1-2 Sketch the capacitor waveform and the output waveform on the laboratory record

sheet, and record the waveform amplitudes and frequency.

1-3 Double the capacitance of C 1 by paralleling it with another 0.1 µF capacitor. Record

the effect on the waveform amplitudes and frequency.

Procedure 2 Monostable Multivibrator.

2-1 Modify the astable multivibrator to convert it into the monostable multivibrator

shown in Fig. 14-2, by including components D1 and C 2 and the necessaryconnecting links. Connect the signal generator, as illustrated.

2-2 Adjust the signal generator to produce a 200 Hz, +2 V, 100 µs pulse wave input.

2-3 Sketch the input, output, and C 1 waveforms on the laboratory record sheet, andrecord the waveform amplitudes and the output pulse width.

2-4 Double the capacitance of C 1 by paralleling it with another 0.1 µF capacitor. Record

the effect on the waveform amplitudes and the output pulse width.





Figure 14-1 Astable multivibrator.

Figure 14-2 Monostable multivibrator

Analysis

1 Explain the astable capacitor and output waveforms obtained for the Procedure 1-2.

2 Compare the frequency and waveform amplitudes measured in Procedure 1-2 with

the design quantities in Example 10.1, and discuss the effects of doubling thecapacitance value.

3 Explain the monostable pulse width and waveform amplitude obtained for the

Procedure 2-3.





4 Comment on the pulse width and amplitude measurements made for Procedure 2-4.

5 Discuss the operation of the astable multivibrator circuit, and explain how addingthe diode converts it into a monostable.






TRIANGULAR WAVEFORM

GENERATOR

Introduction

A triangular waveform generator designed in an example in the text book is constructedand tested. The output amplitude and frequency are monitored, and the effects of

component changes are measured. The circuit is modified for duty cycle adjustment, and

further modified to convert it into a voltage controlled oscillator. The output waveformsare investigated in each case.

Equipment


DC Power Supply—(0 to 12 V, 50 mA)DC Voltmeter

OscilloscopeCircuit Board

Op-amps—(3 × 741) (or alternative with similar specifications)

Resistors—3.9 k Ω, 18 k Ω, (2 × 22 k Ω), (2 × 33 k Ω), 82 k Ω, (2 × 120 k Ω)

Capacitors—(2 × 0.015 µF)Diodes—(2 × 1N914)


Procedure 1 Triangular Wave generator Circuit

1-1 Construct the triangular waveform generator circuit shown in Fig. 15-1, using the

component values determined in Example 10-4 in the text book. Use a ±15 V

supply, and connect the power supply, and oscilloscope as illustrated.

1-2 Switch on the power supply, and monitor the output waveform from each section of

the circuit. Sketch the waveforms on the laboratory record sheet, and record the

waveform amplitudes and frequency.

1-3 Double the capacitance of C 1 by paralleling it with another 0.015 µF capacitor.Record the effect on the amplitude and frequency of the output waveforms.

1-4 Remove the additional capacitor from C 1, and halve the resistance of R2 by

paralleling it with another 18 k Ω resistor. Record the effect on the amplitude andfrequency of the output waveforms.

Procedure 2 Duty Cycle Adjustment

2-1 Switch off the supply, and modify the triangular wave generator for duty cycle

adjustment as shown in Fig. 15-2. Note that the component values used are from






2-2 Switch the supply on again, and adjust R5 to give the largest resistance in series

with R6.

2-3 Measure the frequency, pulse width, and time period of the rectangular wave.

Record these quantities on the laboratory record sheet, and calculate the duty cycle.

2-4 Adjust R5 to give the largest resistance in series with R7, and repeat Procedure 2-3.

Figure 15-1 Triangular waveform generator circuit.

Figure 15-2 Modification for duty cycle adjustment.





Procedure 3 Voltage Controlled Triangular Wave Generator

3-1 Switch the supply off, and modify the circuit to convert it into a voltage controlled

oscillator, using the component values determined in Example 10-6 in the text

book, as illustrated in Fig. 15-3.

3-2 Switch the supply on again, and adjust V B to 9.5 V.3-3 Record the amplitudes and frequency of the output waveforms.

3-4 Adjust V B to 7.5 V and 3.5 V in turn, and repeat Procedure 3-3 in each case.

Figure 15-3 Voltage controlled triangular wave generator.

Analysis

1 Discuss waveforms obtained in Procedure 1-2, and compare the measured

frequency and amplitudes with the design quantities in Example 10-4 in the text book.

2 Discuss the effects of doubling the capacitance of C 1, and the effect of halving the

resistance of R2, as for Procedures 1-3 and 1-4.3 Compare the duty cycle range measurements made for Procedure 2-3 and 2-4 to the

design quantities in Example 10-5 in the text book.

4 Compare the results for Procedure 3-3 and 3-4 with the frequency range specified inExample 10-6 in the text book. Discuss the voltage controlled circuit operation.






TIMER ASTABLE AND MONOSTABLE CIRCUITS

Introduction

A timer astable multivibrator circuit designed in an example in the text book isconstructed and tested. The circuit is then modified into an adjustable frequency square

wave generator, which is then investigated for output waveform and frequency range. A

timer monostable circuit is next constructed and triggered from the square wave

generator. Finally, a sequential timer is constructed, and its output waveforms areinvestigated.

Equipment



Timers—(2 × 555)

Resistors—1 k Ω, 2.7 k Ω, 3.3 k Ω, (2 × 10 k Ω), 180 k Ω

Capacitors—5000 pF, 680 pF, (2 × 0.01 µF), 0.082 µF, (2 × 0.1 µF)Potentiometer—5 k Ω

Diode—1N914

Procedure 1 Basic Timer Astable Multivibrator

1-1 Construct the 555 timer astable multivibrator circuit shown in Fig. 16-1, using thecomponent values determined in Example 10-9 in the text book. Use a +15 V

supply, and connect the power supply and oscilloscope as illustrated.

1-2 Switch on the power supply, and monitor the output waveform at terminal 3, and

the waveform across capacitor C 1. Sketch the waveforms on the laboratory record

sheet, record their amplitudes, pulse widths, and space widths, and show their time

relationships.1-3 Adjust the supply voltage to 5 V, and once again record the waveform amplitudes

pulse widths, and space widths.

Procedure 2 Timer Square Wave Generator

2-1 Switch off the supply, and reconstruct the circuit as shown in Fig. 16-2.

2-2 Set the supply to 12 V and set R2 to zero.

2-3 Switch the supply on and monitor the output waveform at terminal 3 and the

waveform across capacitor C 1. Sketch the waveforms on the laboratory record

sheet, record their amplitudes, pulse widths, and space widths, and show their timerelationships.





2-4 Adjust R2 to maximum resistance, and record the waveform amplitudes, pulse

widths, and space widths.

Figure 16-1 Basic timer astable multivibrator.





Figure 16-2 Timer square wave generator.

Procedure 3 Timer Monostable Multivibrator

3-1 Switch the supply off, and construct a monostable multivibrator capacitor-coupled

to the square wave generator, as illustrated in Fig. 16-3. Note that the monostablecomponent values are taken from Example 10-8 in the text book.

3-2 Set the supply to 12 V, and adjust R2 in the square wave generator to zero.

3-3 Switch the supply on, and monitor the monostable input and output waveforms.Sketch the waveforms on the laboratory record sheet, record their amplitudes, pulse

widths, and space widths, and show their time relationships.





Figure 16-3 Timer monostable multivibrator triggered from an astable.

Figure 16-4 Sequential timer.

Procedure 4 Sequential timer

4-1 Switch the supply off, and construct the astable multivibrator controlled from thesquare wave generator, as shown in Fig. 16-4.

4-2 Switch the supply on, and monitor the square wave generator output and the astable

output. Sketch the waveforms on the laboratory record sheet, record theiramplitudes, pulse widths, and space widths, and show their time relationships.





Analysis

1 Compare the waveforms obtained for Procedures 1-2 and 1-3 to the design

specifications in Example 10-9 in the text book.

2 Discuss the square wave generator waveforms obtained for Procedures 2-3 and 2-4.

Analyze the circuit to determine the maximum and minimum frequencies, andcompare to the measured quantities.

3 Explain the monostable multivibrator waveforms obtained for Procedure 3-3, and

compare the measured output pulse width to the quantity specified in Problem 10-8in the text book.

4 Explain the pulsed tone oscillator waveforms obtained for Procedure 4-2.






SINUSOIDAL OSCILLATORS

Introduction

A phase shift oscillator designed in an example in the text book is constructed and testedfor output amplitude and frequency. The circuit is then modified to include voltage

divider amplitude stabilization, and its output is further investigated. A quadrature

oscillator is similarly investigated with and without amplitude stabilization. A Wein

bridge oscillator, also designed in a text book example, is constructed and tested. In thiscase, diode amplitude stabilization is used, and its the effect on the output is measured.

Equipment



Op-amps—(2 × 714) (or alternative with similar specifications)

Resistors—1.2 k Ω, (3 × 6.8 k Ω), (3 × 8.2 k Ω), 10 k Ω, (2 × 15 k Ω), (2 × 22 k Ω),

(2 × 33 k Ω), (2 × 56 k Ω), (2 × 68 k Ω), (2 × 220 k Ω)Capacitors—(3 × 3300 pF), (3 × 0.01 µF)

Diodes—(4 × 1N914)

Procedure 1 Phase Shift Oscillator

1-1 Construct the phase shift oscillator circuit shown in Fig. 17-1 leaving the diodes outof the circuit at this time. Use a ±12 V supply, and connect the power supply and

oscilloscope as illustrated.

1-2 Switch on the power supply, and monitor the waveforms at the op-amp output and

at the junction of R1 and C 1. Sketch the waveforms on the laboratory record sheet

and record their amplitude and frequency.

1-3 Switch the power supply off, and install the diodes to include the amplitudestabilization components in the circuit.

1-4 Switch the power supply on, and once again record the waveform amplitudes and

frequency.

Procedure 2 Quadrature Oscillator

2-1 Construct the quadrature oscillator circuit shown in Fig. 17-2 leaving the diodes out

of the circuit at this time. Use a ±10 V supply, and connect the power supply and

oscilloscope as illustrated.

2-2 Switch on the power supply, and monitor waveforms at the output of each op-ampand at the junction of R2 and C 2. Sketch the waveforms on the laboratory record





sheet showing their phase relationships and amplitude. Record the waveform

amplitudes and frequency.

2-3 Switch the power supply off, and

install the diodes to

include the amplitudestabilization

components in the

circuit.

2-4 Switch the

power supply on, andonce again record the

waveform amplitudesand frequency.

Figure 17-1 Phase shift

oscillator.





Figure 17-2

Quadrature

oscillator.





Procedure 3 Wein Bridge Oscillator

3-1 Construct the Wein bridge oscillator circuit shown in Fig. 17-3 leaving the diodes

out of the circuit at this time. Use a ±10 V supply, and connect the power supply

and oscilloscope as illustrated.

3-2 Switch on the power supply, and monitor the waveforms at the op-amp output andat its noninverting input. Sketch the waveforms on the laboratory record sheet and

record their amplitude and frequency.

3-3 Switch the power supply off, and install the diodes to include the amplitudestabilization components in the circuit.

3-4 Switch the power supply on, and once again record the waveform amplitudes and

frequency.

Figure 17-3 Wein bridge oscillator.

Analysis

1 Compare the waveforms obtained for Procedures 1-2 to the design quantities in


2 Analyze the amplitude stabilized phase shift oscillator circuit to determine theexpected output amplitude. Compare the calculated and measured quantities.

3 Analyze the quadrature oscillator to determine the output frequency and the output

amplitude with and without amplitude stabilization. Compare the calculated

quantities to the measured quantities in Procedure 3.

4 Compare the waveforms obtained for Procedures 3-2 to the design quantities in






5 Compare the results obtained for Procedures 3-4 to the design quantities in Example







Low-pass and High-pass Filters

Introduction

Two second-order filter circuits designed in examples in the text book are constructed

and tested. A low-pass filter is tested for upper cutoff frequency and output falloff rate. A

high-pass filter is tested for lower cutoff frequency, falloff rate, and circuit upper cutofffrequency.

Equipment

DC Power Supply — (±15 V, 50 mA)Oscilloscope

Sinusoidal Signal Generator — (100 Hz to 11 MHz, ±1 V)

Op-amps —(741, 108) (or alternative with similar specifications)Resistors —(4 × 4.7 k Ω), 18 k Ω, 33 k Ω, 39 k Ω

Capacitors —30 pF, (2 × 1000 pF), 2000 pF,

Circuit Board

Procedure 1 Low-pass Filter

1-1 Construct the second-order low-pass filter circuit shown in Fig. 18-1 using thecomponent values determined in Ex. 12-3 in the text book.

1-2 Before connecting the power supply, switch it on and adjust its output for V CC =

±12 V. Switch the power supply off, then connect it to the circuit and switch on.

1-3 Ground the circuit input and use the oscilloscope to check that the filter circuit isnot oscillating, then connect the oscilloscope and signal generator as illustrated.

1-4 Adjust the signal generator to apply a ±1 V, 100 Hz sinusoidal input to the filter.Check that the output displayed on the oscilloscope is also ±1 V, 100 Hz.

1-5 Keeping the input amplitude constant, increase the signal frequency until the output

level falls to approximately ±0.707 V. Record the filter upper cutoff frequency ( f c)

on the laboratory record sheet.1-6 Increase the signal frequency to 2 f c (keeping the input amplitude constant), then

measure and record the new peak level of the output voltage.

Procedure 2 High-pass Filter

2-1 Construct the second-order high-pass filter circuit shown in Fig. 18-2 using thecomponent values determined in Example 12-4 in the text book.


±15 V. Switch the power supply off, then connect it to the circuit and switch on .

2-3 Ground the circuit input and use the oscilloscope to check that the filter circuit is

not oscillating, then connect the oscilloscope and signal generator as illustrated.





2-4 Adjust the signal generator to apply a ±1 V, 50 kHz sinusoidal input to the filter.

Check that the output displayed on the oscilloscope is also ±1 V, 50 kHz.

2-5 Keeping the input amplitude constant, reduce the signal frequency until the output

level falls to approximately ±0.707 V. Record the filter lower cutoff frequency ( f c)

on the laboratory record sheet.

2-6 Reduce the signal frequency to f c/2 (keeping the input amplitude constant), thenmeasure and record the new peak level of the output voltage.

2-7 Increase the signal frequency through f c (keeping the input amplitude constant) until

the output level falls to approximately ±0.707 V once again. Record the circuitupper cutoff frequency ( f 2) on the laboratory record sheet.

Fig. 18-1 Second-order low-pass filter circuit and connection diagram





Fig. 18-2 Second-order high-pass filter circuit and connection diagram.

Analysis

1 Compare the low-pass filter cutoff frequency measured in Procedure 1-5 with the

design quantity in Example 12-3 in the text book.

2 Use the voltage levels measured in Procedures 1-5 and 1-6 to calculate the low-passfilter output falloff rate. Compare to the theoretical falloff rate.

3 Compare the high-pass filter cutoff frequency measured in Procedure 2-5 with the

design quantity in Example 12-4 in the text book.

4 Use the voltage levels measured in Procedures 2-5 and 2-6 to calculate the high- pass filter output falloff rate.

5 Calculate the upper cutoff frequency for the high-pass filter, and compare it to the

cutoff frequency measured in Procedure 2-7.






BAND-PASS FILTERS

Introduction

Two band-pass filter circuits designed in examples in the text book are constructed andtested. A single-stage filter is tested to determine its upper and lower cutoff frequencies

and the output falloff rate beyond these frequencies. A state-variable filter using three op-

amps is tested for center frequency and upper and lower cutoff frequencies.

Equipment

DC Power Supply — (±15 V, 50 mA)

OscilloscopeSinusoidal Signal Generator — (10 Hz to 100 kHz, ±1 V)

Op-amps — (3 × 741) (or alternative with similar specifications)Resistors — (3 × 5.6 k Ω), (2 × 1 k Ω), (6 × 15 k Ω), 120 k Ω Capacitors —1000 pF, (2 × 0.01 µF), 0.1 µF

Circuit Board

Procedure 1 Single Stage Band-Pass Filter

1-1 Construct the single-stage band-pass filter circuit shown in Fig. 19-1 using thecomponent values determined in Example 12-7 in the text book.


±12 V. Switch the power supply off, then connect it to the circuit and switch on.1-3 Ground the circuit input and use the oscilloscope to check that the filter is not

oscillating, then connect the oscilloscope and signal generator to the circuit as

illustrated.1-4 Adjust the signal generator to apply a ±1 V, 3 kHz sinusoidal input to the filter.

Check that the output displayed on the oscilloscope is also ±1 V, 3 kHz.1-5 Keeping the input amplitude constant, decrease the signal frequency until the

output level falls to approximately ±0.707 V. Record the filter lower cutoff

frequency ( f 1) on the laboratory record sheet.

1-6 Reduce the signal frequency to f 1/2 (keeping the input amplitude constant), then

measure and record the new peak level of the output voltage.

1-7 Increase the signal frequency through 3 kHz (keeping the input amplitudeconstant) until the output level falls to approximately ±0.707 V once again.Record the filter upper cutoff frequency ( f 2) on the laboratory record sheet.

1-8 Still maintaining the input amplitude constant, further increase the signal

frequency to 2 f 2. Measure and record the new peak level of the output voltage.





Procedure 2 State-Variable Band-Pass Filter

2-1 Construct the state-variable band-pass filter circuit shown in Fig. 19-2 using the

component values determined in Example 12-11 in the text book.


±15 V. Switch the power supply off, then connect it to the circuit and switch on.2-3 Ground the circuit input and use the oscilloscope to check that the filter is not

oscillating, then connect the oscilloscope and signal generator to the circuit as

illustrated. 2-4 Adjust the signal generator to apply a ±0.1 V, 1 kHz sinusoidal input to the filter.

Carefully adjust the frequency for maximum amplitude at the A2 output, which

occurs at the filter center frequency ( f o). Record f o and the output amplitude.

2-5 Keeping the input amplitude constant, reduce the signal frequency until the output

level falls to approximately ±0.707 V. Record the filter lower cutoff frequency ( f 1)

on the laboratory record sheet.

2-6 Increase the signal frequency through f o (keeping the amplitude constant) until the

output level falls to approximately ±0.707 V once again. Record the filter uppercutoff frequency ( f 2) on the laboratory record sheet.

Fig. 19-1 Single-stage band-pass filter circuit and connection diagram.





Fig. 19-2 State-variable band-pass filter circuit and connection diagram.

Analysis

1 Compare the single-stage band-pass filter upper and lower cutoff frequencies

measured in Procedures 1-5 and 1-7 with the design quantity in Example 12-7 in thetext book.

2 Use the voltage levels measured in Procedures 1-6 and 1-8 to calculate the falloff

rates for the single-stage band-pass filter. Compare to the theoretical falloff rate.





3 From the measured quantities at the center frequency (Procedure 2-4), calculate the

circuit closed loop voltage gain for the state-variable band-pass filter. Compare to thecalculated gain in Example 12-11.

4 Compare the state-variable filter center frequency and cutoff frequencies measured in

Procedures 2-4 through 2-6 with the design quantity in Example 12-11 in the text

book.






Series Voltage Regulators

Introduction

Two series regulator circuits designed in examples in the text book are constructed andtested. An op-amp regulator is first tested for output voltage range, source effect, and

load effect. The circuit is modified to include current limiting, and the regulator short

circuit current is investigated. The second regulator circuit uses a 723 IC regulator. Tests

are performed to determine its line and load regulation.

Equipment

DC Power Supply—(0 to ±25 V, 250 mA)Voltmeter—(0 to 25 V)

Voltmeter—4½ Digital DVMAmmeter—(0 to 200 mA)Op-amp—741 (or alternative with similar specifications)

IC Voltage Regulator—723 (or alternative with similar specifications)

Resistors (0.25 W)—4.7 Ω, 270 Ω, 3.9 k Ω, 4.7 k Ω, 6.8 k Ω, 22 k Ω, 33 k Ω, 150 k Ω Resistors (0.5 W)—(2 × 10 Ω)

Resistors (2.5 W)—60 Ω

Variable Resistors (2 W)—150 Ω

Potentiometer—35 k Ω Capacitors —100 pF, 100 µF

BJTs—2N718, (2 × 2N3904) (or alternatives with similar specifications)

Zener diode—1N757 (or alternative with similar specifications)Circuit Board

Procedure 1 Op-amp Voltage Regulator

1-1 Construct the op-amp voltage regulator circuit shown in Fig. 20-1(a) and (b),

using a heat sink on transistor Q1. Note that the circuit uses the component values

determined in Examples 13-2, 13-4, and 13-5 in the text book.

1-2 Switch on the source voltage power supply, adjust it to 20 V, and adjust R4 to give

a 12 V output (V o). Note that a digital voltmeter that measures V o to at least three

decimal places should be used.1-3 Measure and record (on the laboratory record sheet) the voltage levels at thefollowing points with respect to ground: Q1 base, Q2 base, D1 cathode, R4 moving

contact.

1-4 Adjust the R4 moving contact to its maximum point in one direction, and then inthe other direction. Record the regulator output voltage in each case, then readjust

R4 for V o = 12 V.





1-5 Adjust the source voltage to 22 V and then to 18 V. Record the output voltage

change in each case, then readjust the source voltage to 20 V.

1-6 Connect the 60 Ω, 2.5 W load resistor, ammeter, and switch (S 1) at the regulator

output, as illustrated in Fig. 20-1(c).

1-7 Carefully monitoring the output voltage, briefly close S 1 to switch the load

resistor into the circuit then open S 1 again. Record the measured output voltagechange that occurred when the load resistor was connected. Also record the load

current.

Fig. 20-1 Op-amp voltage regulator.

Procedure 2 Output Current Limiting

2-1 Switch off the source supply voltage and modify the circuit to include the current

limiting components (Q3, R6, and R7), as illustrated in Fig. 20-2. Connect the 150Ω adjustable load resistor ( RL) in place of the 60 Ω resistor in Fig. 20-1(c).

2-2 Set RL to its maximum resistance, and switch the source voltage on. Check that V o

= 12 V, and adjust R4 as necessary.





2-3 Close S 1, and slowly adjust RL until V o commences to fall. Record V o and I L at this

point.

2-4 Further adjust RL toward zero resistance so that it short-circuits the regulator

output. Record the short circuit current ( I SC).

2-5 Open S 1 once again, and check that V o returns to its previous unloaded level.

Procedure 3 723 IC Voltage Regulator

3-1 Construct the 723 IC regulator circuit shown in Fig. 20-3. Note that the circuit

uses the component values determined in Examples 13-8 in the text book.

3-2 Set RL to its maximum resistance, then switch on the source voltage power supplyand adjust it to 17 V.

3-3 Measure and record V o and V R2. Note that a digital voltmeter that measures V o to

at least three decimal places should be used for measuring V o.

3-4 Adjust the source voltage to 18.7 V and then to 15.3 V. Record the output voltage

change in each case, then readjust the source voltage to 17 V.3-5 Close S 1, and slowly adjust RL until V o commences to fall. Record V o and I L at this

point.3-6 Further adjust RL toward zero resistance so that it short-circuits the regulator

output. Record the short circuit current ( I SC).

3-7 Open S 1 once again, and check that V o returns to its previous unloaded level.

Fig. 20-2 Current limiting test circuit.





Fig. 20-3 723 IC Regulator.

Analysis

1 Compare the op-amp regulator voltage levels measured in Procedures 1-3 and 1-4

with the design quantities in Examples 13-2, 13-4, and 13-5 in the text book.2 Using the voltage levels measured in Procedures 1-5 and 1-7, calculate the regulator

source effect, load effect, line regulation, and load regulation.

3 Compare the short circuit current measured in Procedure 2 to the design quantity inExample 13-6.

4 Compare the 723 regulator voltage levels measured in Procedure 3-3 to the design

quantities in Example 13-6 in the text book.





5 Using the voltage levels measured in Procedures 3-4 and 3-6, calculate the regulator

source effect, load effect, line regulation, and load regulation.






Power Amplifier

Introduction

A BJT output class AB power amplifier with an op-amp driver is constructed and testedfor dc and ac performance. The dc voltage levels throughout the circuit are first checked

without the load resistor connected. The load resistor is connected, an ac input signal is

applied, and the amplifier waveforms, frequency response, output power, and efficiency

are investigated.

Equipment

DC Power Supply—(±17 V, 200 mA)DC Voltmeter—(0 to 50 V)

Two DC Ammeters (0 to 200 mA)OscilloscopeAudio Range Signal Generator

BJTs—2N718, 2N722 (or alternatives with similar specifications)

Heat sinks for BJTsDiodes—(2 × 1N914)

Op-amp—LF356 (or alternative with similar specifications)

Resistors (0.25 W)— (2 × 8.2 Ω), 470 Ω, (4 × 1.5 k Ω), (2 × 10 k Ω), 82 k Ω,

Resistors (2 W)—100 Ω Capacitors —330 pF, 3.3 µF, 6.8 µF, (2 × 100 µF)

Circuit Board

Procedure 1 DC Conditions

1-1 Construct the amplifier circuit shown in Fig. 21-1, using a heat sinks on both

BJTs. Leave the signal generator and load resistor ( RL) unconnected at this time.1-2 Switch on the power supply and adjust it for V CC = ±17 V.

1-3 Use the oscilloscope to check that the circuit is not oscillating.

1-4 Measure and record the dc voltage levels through the circuit as listed on thelaboratory record sheet.

1-5 Connect the 100 Ω load resistor and check that the dc output voltage remains

zero.

Procedure 2 AC Measurements

2-1 Connect the signal generator to the amplifier input, and the oscilloscope tomonitor the input and output waveforms. Connect ammeters to measure the power

supply (dc) currents.





2-2 Set the signal generator frequency to 3 kHz, and adjust the signal amplitude to

produce the largest undistorted amplifier output waveform.


the peak voltages. Also record the dc supply currents.

2-4 Adjust the signal frequency in steps as listed on the laboratory record sheet, taking

care to keep the signal amplitude constant. Record the output voltage amplitude ateach signal frequency.

2-5 Change capacitor C 2 to 1 µF, and investigate the new low cutoff frequency ( f 1).

2-6 Connect a 330 pF capacitor in parallel with R3, and investigate the new highcutoff frequency ( f 2).





Fig. 21-1 Op-amp/BJT power amplifier.

Analysis

1 Analyze the circuit to determine the dc voltage levels throughout the circuit, and

compare to the voltages measured for Procedures 1-4.





2 From the results of Procedure 2-3 calculate the closed-loop gain, dc input power, ac

output power, and circuit efficiency. Analyze the circuit to determine these quantities,and compare to the result obtained from the measurements.

3 From the results of Procedure 2-4 plot the amplifier frequency response, and estimate

the upper and lower cutoff frequencies( f 1 and f 2). Calculate f1 from the circuit

component values, and compare it to the experimentally determined f 1. Comment onthe measured f 2.

4 Calculate the new low and high cutoff frequencies for the changes made in

Procedures 2-5 and 2-6. Compare the calculated and measured quantities.



349 28 Lab-manual Lab-manual Op Amp 3e LabManual

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