ee2002 lab manual fall 2013

8/13/2019 EE2002 Lab Manual Fall 2013

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University of Minnesota

Department of Electrical andComputer Engineering

EE 2002 Laboratory Manual

An Introductory Circuits/Electronics

Laboratory Course


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Introduction

You will find this laboratory to be different than those you have experienced up to this time. Itwas designed with several objectives in mind. First, it is intended to supplement the lecture

course EE2001 and can only be carried out with the maximum benefit if you are acquainted with

the topics being discussed there. Second, it is intended to develop your self-confidence inlaboratory procedures and in drawing conclusions from observations.As a consequence the

instructions are very spare and assume you will be able to extract conclusions from eachexperiment and will relate parts of the total lab to each other without being explicitly asked to doso.

Important Points

- Your grade in this course will depend principally on your in-lab work.

- You are expected to maintain a lab notebook. It must contain a running account of theexperiment. It is not intended to be a book into which you copy notes previously gathered on

the back of an envelope. It must however be legible and coherent. Write in such a way that

another person could perform the same experiment based on your account, and this same personcould understand the conclusions that you drew from your data. It is not necessary to hide your

mistakes. If you make a mistake in an entry simply draw a line through that entry and start over -

you will not be penalized for this.

- The lab notebook should have the following characteristics:

- It should be a bound notebook (spiral bound is OK).

- Lab entries should be dated, and should include:- Complete circuit diagrams.

- Explanation of circuit, methods, procedures, etc.

- All calculations for designs.

- All measurements (including component values).- All analysis and comparisons of data with theory.

- Homework

- There is no formal lab homework or pre-lab work in this course, but it will pay great

dividends for you to make a careful reading of the experiment description before arriving inthe laboratory. You will also note that some parts of the "experiments" involve analytical

work which can be better done elsewhere. Most problems students have with this course

are due to lack of preparation prior to coming to lab. If after reading through the lab andconsulting the relevant section of your EE2001 text you do not understand something, seek

out either your TA or the faculty member in charge of the lab.

- If you do not spend at least 30 to 40 minutes studying the experiment, making notes, circuit

diagrams, calculations, etc. in your laboratory notebook, prior to coming into the lab, you

will not finish the experiments. It will be obvious to everyone in the class, including your

classmates, your Teaching Assistant, and your professor, that you have come in unprepared.

And you will receive no extra help for such poor performance.

- MILESTONES.

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- In each experiment there will be a few milestones. These are specific tasks which must be

accomplished and demonstrated to the TA or professor before going on to the next item. All

milestones must be completed or you will not pass the course. If the milestones are notcompleted by the end of the quarter you will receive an F for the course. While the

milestones are not a part of the grade formula, delays in milestone completion will

unavoidably delay the submission of your lab notebook with the corresponding gradepenalty. Lab notebooks and lab reports will not be accepted if the milestones for the

corresponding lab have not been completed.

- Grades

Grades will be determined from the following components of the course:

Lab Notebooks - 30%

Lab Practical Exams - 40% Take them seriously, they are forty minutes to one hour

in duration and they account for a significant portion ofyour final grade.

Lab Reports - 30%

Lab notebooks will be collected up to three times during the quarter. They will be due at 4:30

PM three working days after the scheduled completion date of a lab.

Lab reports will be collected one week after scheduled completion of the corresponding lab.

You will be given a schedule during the first week of class which will contain all lab

practical exam dates and notebook and lab report due dates.

- Late Penalties. The penalties for late notebooks or lab reports are as follows:

1 or 2 days late: 3% deducted from your FINAL SCORE.

3 or 4 days late - an additional 3% deducted from your FINAL SCORE. and so on...

Check the class website for a separate handout detailing the requirements for the lab reports.

- Housekeeping Requirements.

No food or drink to is be brought into the lab and most especially is not to be placed on the labbenches. At the conclusion of each laboratory session, all cables, etc. are to be returned to the

proper wire racks and any borrowed equipment (there should be no borrowed equipment without

the approval of the TA) returned to its proper location. The only items on the lab bench whenyou leave should be the equipment normally found on each bench. The TA will record a demerit

against your record in his gradebook each time you fail to meet the above standards. Four or

more demerits at the end of the term after grades have been computed will result in grade

reduction of one level (A to A-, A- to B+, etc.). If for some reason, you find the lab bench doesnot meet the above standards when you first come in, inform your TA immediately. You are still

responsible for leaving the lab bench neat when you leave.

Experiment Schedule Fall Semesters

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Experiment #1: Lab Procedures &Equipment Familiarization

Session #1

Introduction

The lab instructor will explain procedures

and expectations for this course. He willthen demonstrate the use of the digital

multimeter (DMM), oscilloscope, function

generator, dc power supply, and how towire circuits on the protoboard in each

student lab kit. The student should then

spend the rest of the lab t to become more

familiar with the equipment.

Measurements

1. Connect the 0-20V positive dc supply

terminals from the DC power supply to

Ch1 of the scope and to the as shown in

Fig. 1-1. Vary the setting of the dc output

and compare with the reading of the

DMM and the scope

Figure 1-1. Connection of dc power

supply digital multimetes (DMM) and

oscilloscope for measuring dc voltagse.

Be sure that the DMMis set to read DColts

and that Ch1 of the scope is dc coupledwith the proper vertical scale factor.

2. Display a 4 V peak-to-peak sinewave at

a frequency of 1 kHz on the oscilloscope.

Connect the function generator to theoscilloscope as shown in Fig.1- 2 to

obtain the display. Adjust both the vertical

sensitivity (volts per division) and

horizontal (time base) sensitivity (seconds,

milliseconds, microseconds) to obtain a

good display showing two or three cycles

of the waveform.

Figure 1- 2. Connection of function

generator to oscilloscope for displaying

and measuring ac waveforms. The

connection of the DMM to measure rms

voltages is also shown.

3. Measure the amplitude of this ac

waveform with the DMM set on the ac

voltage mode. Compare this reading with

the base-to-peak value you observe on the

oscilloscope.

The voltage measurements in steps #2 and

step #3 should have different values. TheDMM is calibrated to display the rms

value of a sinewave which equals 0.707 of

the base-to-peak value of a sinewave.

5

0 20V

0 20V

+

-

0 - 6V

Triple DC

power supply

Oscilloscope DMM+

+

-

-

Oscillocope DMMFunctiongenerator

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Other waveforms such as square wavesand triangular waves will have different

rms-to-base-to-peak ratios as

measurements of step #5 will illustrate.

4, Repeat steps 23 and 34 with squarewaves and then triangle waves.

A square wave has an rms value which is

equal to the base-to-peak value. A triangle

wave has an rms value value which is0.578 of the base-to-peak value.

.

5. Construct the circuit shown below in

Fig. 1-3, sometimes termed a voltage

divider. Use a 4 V peak-to-peak 1 kHz

sinewave for the input and measure theoutput voltage with the oscilloscope and

DMM.

The point of this step is to become familiarwith using the protoboard to construct

circuits and make connections to sources

and measurement instruments. Examinethe layout of the protoboard shown below

in Fig. 1-4 and note that a specific column

of component insertion holes are shorted

together. Each individual terminal of acomponent should be inserted into a

separate column as illustrated for a resistor

unless it is desired to have terminalsshorted together.

Electrical connections to the functiongenerator and oscilloscope are made via

so-called BNC connector terminals. The

outer cases of these connectors are directly

connected to the ground (ground pin) ofthe ac power plug. When these instruments

are connected to the AC power outlets, all

of the instruments grounds (BNC outercases) are shorted together as indicated in

the figure. Any instrument that connects to

the AC power system is configured in thismanner (for reasons of safety). Thus it is

not possible to connect the oscilloscope so

as to measure the voltage across the 4 kresistor because the 1 k resistor wouldthen be shorted out.

Fig. 1-3. Voltage divider circuit and

instrument grounding.

Fig. 1-4. Diagram of protoboard which is

used to construct circuits for laboratory

measurements.

6. Construct the circuit of Fig. 1-5. Set the

DMM to measure dc currents. In this

configuration the DMM is being used to

measure current.

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Figure 1-5. Circuit arrangement for

measuring current through a resistor.

Compare the current measured by the

DMM with the current output indicated bythe dc power supply display. They should

be the same.

7. Construct the circuit of Fig. 1-6 and use

it to measure the resistance of several of

the resistors in your lab kit. Make sure to

use the proper set of terminals on the

DMM and set the DMM to measure

resistance.

Figure 1-6. Circuit for determining values

of resistors.

Compare the reading of the DMM with the

value of resistance indicated by the colorcode on the resistor body.

Experiment #2: DC Measurements

Sessions #2 and #3

Experiments1. Measure the voltage of a nominal 1.5v

AAA cell to the nearest millivolt.

2. Determine experimentally the value ofresistor that, when place across the cell,

will make a measurable change in the

measured cell voltage. Calculate theinternal resistance of the cell.

3. Measure the voltage range of each of

the power supply outputs. A laterexperiment will require a voltage which

can be adjusted over the range 0 to 40v.Decide how you would provide such avoltage.

4. Set a power supply output to the valueof the cell voltage measured in item 1.

Determine the change in this voltage when

the supply is loaded with the resistor usedin item 2.

5. Design a circuit to light the red light-

emitting diode (LED). The LED currentmust be about 15 ma (no more!). The

diode voltage will be about 1v but you

must not connect a voltage source directlyto the diode because the current is a very

strong function of this voltage and chances

are that the diode current would exceed themaximum allowed.

NOTE: The short lead of the diode is the

cathode, i.e. the negative lead.

_________________________________

MILESTONE #2-1: Demonstrate your

LED circuit to your instructor, making

sure that meters are connected to showdiode current and voltage and that there is

no possibility of exceeding the specified

maximum diode current.__________________________________

Demonstration

7

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The instructor will demonstrate the use ofthe oscilloscope to measure periodic

waveforms and to display one variable

versus another. The signal generator will

also be demonstrated.

Experiments6. Connect a voltage divider to an output

of the power supply. Design it to give anoutput that is 1/3 of the supply voltage and

so that neither the power ratings of the

resistors nor the current rating of thesupply are exceeded. The voltage output

of the divider must not change by more

then 1% when loaded with 10K.

7. Design a current divider that will

provide a 1/3 - 2/3 current split. Observethe current and power limitations as youdid in the previous item. Another design

constraint is that the current meters

inserted to measure the current divisionratio must not upset this ratio.

__________________________________

MILESTONE #2-2: Demonstrate yourcurrent divider. Show that the current

meters have no effect on the current

division.

__________________________________

8. Construct a non-trivial resistive circuit

with at least 2 loops and at least 3 resistorsin each loop. Verify Kirchhoff's laws for

this circuit. Notice that this item is more

"open ended", i.e. there is more room forindividual initiative. These lab instructions

will be increasingly presented in this

mode.

__________________________________

MILESTONE #2-3: Demonstrate yourworking circuit. Be prepared to show one

or two branch voltages and how theycompare to those calculated in your notes.

__________________________________

Experiment #3: Circuit Theorems

Session #4

Experiments1. Construct a resistive circuit containing

series and parallel branches and a DCvoltage source. Measure the voltage at at

least 2 nodes (relative to a reference node)as a function of the source voltage.

Measure the current in at least 2 branches

as a function of the source voltage.

2. Construct the circuit shown below. Use

the triple power supply at the lab bench.

Note that all three of the outputs havefloating terminals, i.e. not connected to

ground.

Verify the superposition theorem for at

least 2 nodes and 2 branches.

3. Design and construct another resistive

network containing 3 voltage sources.Determine selected node voltages and

branch currents analytically and

experimentally.

4. Construct the circuit shown below.

.

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Determine, experimentally and

analytically. the Thevenin equivalent atthe port shown.

__________________________________MILESTONE #3-1: Explain to your

instructor how you carried out item 4.

Quiz #1 on Exps. #1, 2, and 3Session #5

Experiment #4: Op Amps

Session #6

DemonstrationYour instructor will demonstrate some

applications of operational amplifiers.

Experiments

1. To ensure that the output of the

amplifier is zero when the differentialinput is zero ("offset nulling") the scheme

shown

is used. (The potentiometer is adjusted to

force the output to zero when the inputterminals are both zero.) Design and

construct a non-inverting amplifier with avoltage gain of approximately 10, null its

offset and measure the gain over the

complete range of input voltages.

2. Power the opamp with +5 and -5vsupplies and monitor its output when one

input is grounded and the other varied afew millivolts on either side of zero.

3. Repeat with the roles of the inputterminals interchanged.

4. Design and construct a circuit which

will indicate whether an unknown voltageis greater than or less than a given

reference voltage. The latter should becapable of being varied between -5 and +5volts.

__________________________________

MILESTONE #7-1: Demonstrate howyour circuit can convert a sine wave to a

square wave with a variable duty cycle.

__________________________________

5. To your comparator circuit of item 4

add green and red LED's so that the green

lights up when the input voltage is lessthan the reference and the red when it is

greater.

6. Using resistors in the few K range,

design a voltage divider to provide an

output of about 5v from a 15v source.

7. Determine the load on the divider which

will drop the output voltage to 75% of the

no load value.

8. Construct a 741 buffer (unity gain, non-

inverting amplifier) to insert between theoutput of the divider and the load

determined in item 7.

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Experiment #5: I-V Curves and Load

Lines

Session #7

DemonstrationThe instructor will demonstrate the smallsignal resistance versus dc current level

for a diode and will discuss the load line

method.

Experiments1. Measure the current vs. voltage relation

of the incandescent lamp supplied. Limitthe current thru the lamp to 100 mA

maximum.

2. Using your data from item 1 and the

load line approach, determine the lamp

current expected for the following valuesof power supply voltage and series

resistor.

Voltage Resistance

6V 100

3V 100

3. Check the results of item 2 by directmeasurement.

4. Build this circuit and, driving it with thesignal generator, display on the scope the

output voltage versus the input voltage.

5. Change the circuit so that it limits for

negative input voltages.

6. Change the circuit so that it limits at

+2 v.

7. Change the circuit so that it limits at

+2v and also at -2v.

__________________________________


circuit of item 7.__________________________________

8. Show the influence of your circuit of

item 7 on various input periodic

waveforms.

Experiment #6: Diodes & Rectification

Session #8.

Experiments

1. Measure the current-voltage relation for

the 1N4740 diode over its entire allowable

ranges of voltage and current. Obtain acollection of data points.

2. Use the data of item 1 to determine thesmall signal resistance of the diode at

forward currents of 10, 20 and 30 ma.

3. Devise a large-signal model for your

Zener diode, applicable in the reversebreakdown region for currents from 10 to

50 ma.

4. Repeat the forward bias measurements

of step 1 using the DiodeIV and use the

10

Demonstration

The measurements in steps 1 and 2

were point-by-point manualmeasurements. These measurements

can be automated using the PXI

equipment run under the control of aLabView VI (virtual instrument)

entitled DiodeIV which is found in theUofMNIV folder. Your lab instructorwill demonstrate the use of this virtualinstrument.


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saved data to repeat step 2. Compare withthe manually acquired results.

5. Examine the output of this circuit for 1

KHz sinusoidal input amplitudes from 0.5

to 5v.

6. Investigate the following power supplycircuit (known as a bridge circuit).

Note: The output is floating with respect to

ground (i.e. both ends of the output are off

of ground). Hence a single scope channelcannot be put across the load. Instead both

channels of the scope must be set up as

shown. The polarity of Ch 1 should beinverted with respect to Ch 0. Both

channels must have the same V/cm setting

and both reference levels (zero voltagelines) must lie on top of each other. When

the scope is set up in this manner, it is

acting as a so-called pseudo-differentialinput. Trigger the scope from Ch 0.

7. Determine the effect of placing a large

capacitor across the load of the circuit ofitem 6. Make sure you observe the proper

polarity when connecting the capacitor.

__________________________________

MILESTONE #6-1: Demonstrate the

load voltage of the circuit of item 6, withand without the filter capacitor.

__________________________________

Experiment #7: MOSFETCharacteristics and Amplifiers

Sessions #9 and #10

Demonstration session #9The instructor will demonstrate the use of

a LabView VI (found in the UofMNIV

folder) entitled FETVI which automates

the measurements of FET outputcharacteristics (drain current as a function

of drain-source voltage with gate-sourcevoltage as a parameter) and transfercharacteristics (drain current as a function

of gate-source voltage).

ExperimentsThe experiments below all involve

measurements on a MOSFET. You willuse the 2N7000 n-channel enhancement

MOSFETs which are part of your lab kit.

The diagram shown below shows the

pinouts.

1. Use the FETVI to measure ID versus

VDSfor various values of VGS for two

separate 2N7000 MOSFETs. Determine

the transconductance of each device at

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several drain current levels. The drain-source voltage should go to at least 5V to

insure the devices go into the active

(saturation) region but do not exceed 10V.

Limit the maximum drain current to 40

mA or less.

2. Determine the threshold voltage of eachdevice.

__________________________________

MILESTONE #7-1: Explain to yourinstructor how you deduced the threshold

voltages.

__________________________________

3. Use the data of item 1 to determine the

conductance parameters (K) for the 2devices. Using a reasonable value ofcarrier mobility, determine the oxide

thickness for the 2 devices.

4. Determine the channel length

modulation parameter () or equivalently

the Early voltage VA = 1/ for the n-

channel MOSFET using the data from step

1.

Demonstration session #9The instructor will demonstrate some

methods of biasing FETs.

Experiments5. Design circuit arrangement(s) tomeasure the small-signal ac

transconductance for both of the devices

used in step #1. Make the measurements at1 kHz and at several values of dc drain

current.

__________________________________MILESTONE #7-2: Before taking anymeasurements, explain the circuit to your

instructor.

__________________________________

6. Construct and test the common source

MOSFET amplifiier shown below using

one of the n-channel MOSFET measuredin Step #1. Measure the following small

signal parameters at a frequency of 1 kHz:

a. Input resistance Rinseen at the Vi

terminals.b. Voltage gain Vo/Vi

c. Power drawn from the 10 V power

supply.d. Maximum undistorted sinewave output

voltage swing in volts pp.

__________________________________


operating amplifier to your instructor.

7. Design and construct the MOSFET

current mirror (current sink) shown belowusing the 2N7000 MOSFETS. Determine

the range of Rloadover which the current

through the resistor is a reasonably

constant current of 5 mA.

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Quiz #2 (Exps. 1-7)

Session #11

Experiment #8

Transients in RC and RL CircuitsSessions #12

1. Construct a simple RC single timeconstant circuit of the form shown below.

Choose component values such as to make

the time constant about 0.1ms anddetermine the time constant

experimentally by observing output

voltage when a square wave is applied tothe input port. The value of R should be

significantly larger than the output

resistance of the source proving the inputvoltage Vin.

2. Measure the rise and fall time of the

output waveform in step #1.

MILESTONE #8-1. Demonstrate your

measurement of the rise and fall timemeasured in step #2 to your lab instructor.

__________________________________

3. Apply a square wave to the circuit used

in Step #1 and note the output waveform.The period of the square wave should be

much shorter than the time constant foundin step #1.

4. Many applications require that a sharppulse be generated to mark the time at

which a rapid change occurs in a signal.

Design a simple circuit based on the work

of the preceding items which will generatea sharp spike whenever the square wave

input changes sign.

5. The circuit used in step #4 is a

differentiator circuit over some range of

input frequencies. Apply a triangular waveto the circuit used in step #3. Vary the

frequency of the triangular wave and

determine approximately the highestfrequency that the circuit behaves as a

differentiator.

6. Construct the single RL single timeconstant circuit shown below. Use the 100

mH inductor in your lab kit and use a 1 k

resistor for R. Measure the time constantof the circuit.

7. Determine if the RL circuit of step #6 is

and integrator or differentiator.

Approximately determine the maximum

frequency (if the circuit is a differentiator)or the minimum frequency (if the circuit is

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an integrator) that the circuit will functionas a differentiator or integrator.

MILESTONE #8-2. Show the operation

of the RL circuit of step #7 as either a

differentiator or integrator and show themaximum or minimum frequency of

operation as either a differentiator or

integrator.__________________________________

8. Take the components (R and L) used in

the circuit for steps #5 and #6 andconstruct a circuit that has the same square

wave response as the circuit of step #1.

Determine the rise and fall time of the

output waveform.

Experiment #9Transients in RLC Circuits

Session #13

1. Construct the RLC circuit shown below.Drive the circuit with a 2V p-p square

wave with a frequency of 100 Hz. Using

the observed output waveform, determine

the resonant frequency fo(2 f o={LC}-0.5)

and quality factor Q (Q= 2 f oL/RL) of the

circuit.

2. Replace the 5 nF capacitance with a 20nF capacitance Again determine theresonant frequency and quality factor

using the same input signal as in step #1.

__________________________________

MILESTONE #9-1. Demonstrate the

operation of the series resonant circuit ofstep #1 to your instructor. Using your

measured value of Q, estimate the inductor

series resistance RLand show your lab

instructor.

3. Construct the parallel RLC circuit

shown below. Drive the circuit with a 4V

p-p square wave with a frequency of 200Hz. Using the observed output voltage,

determine the resonant frequency and

quality factor Q of the circuit.

4. Replace the 5 nF capacitance with a 20nF capacitance Again determine the

resonant frequency and quality factor

using the same input signal as in step #3.

5. Revise the circuit of step #4 so that it is

critically damped (Qp= 0.5) without

changing the value of the capacitor or

inductor. Drive the circuit with the same

input signal as in step #3 and verify that

the circuit is critically damped. What valueof resistance critically damps the circuit?

Experiment #10: CMOS Logic Inverter

Session #14(NOT DONE IN FALL SEMESTERS)

1. Measure the transfer curve Vyversus

Vafor one of the six CMOS inverters on

the 78HCU04 IC in you lab kit. Bias the

inverter with 5V (i.e. VCC= 5V). Vary

14

6 ,100 $.V

inV

out

+ +

- -

3 nF


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VAfrom 0-5V. See the pinout diagram

and logic diagram below. Be sure that the

VAterminals of the five unused inverters

are shorted to ground so that they cannot

influence the measurements. (If the VA

of

the unused inverters are left floating, theymay acquire a charge and hence a voltage

that could turn on the unused inverters.)

2. Use your measured transfer curve to

determine the logic level voltages (positivelogic) VOH, VOL, VIH, and VIL.

Estimate the noise margin of the inverter

from these voltage levels.

3. Load the output of an inverter with a 10

nF capacitor. Determine the average

power drawn from the 5V V

CC

supply as

you vary the frequency of a 5V base-to-peak square wave to the input A of the

inverter. Go to frequencies as high as 1

MHz. Use the interface circuit shownbelow to apply the input signal from the

function generator to inverter input. The

purpose of this interface circuit is to

prevent negative going pulses from beingapplied to the inverter.

4. Measure the propagation delay of the

inverter using the ring oscillator shown

below. It can be shown that thepropagation delay is given by tpd= T/(2N)

where T is the period of oscillation of the

ring oscillator and N is then number of

inverters in the oscillator. As before use5V for the VCCsupply. If the circuit is set

up properly, the circuit will oscillate

(produce periodic waveforms) without anyac input

MILESTONE #9-1. Demonstrate yourmeasurement of the propagation delay to

your lab instructor.

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ee2002 lab manual fall 2013

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