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1. TTL level square wave output is available for signal source for digital circuit experiments Variable symmetry to generate sawtooth and pulse waveform Frequency of output signal can be controlled by applying voltage from 0 to 10 V to VCF IN connector The linear sweep function provides SWEEP FUNCTION CONTROL from 1 1 to 100 1 DC voltage from 0 to 10 V can be overload upon output waveform Maximum attenuation over 40 dB Elecrtronics 10 Fig 1 5 Function Generator SUMMARY The most common scope in use today is the triggered sweep scope Older scopes were the recurrent sweep type The typical scope has four sections vertical horizontal trigger or sync and display The vertical section of the scope conditions the input and causes the beam in the CRT to be deflected vertically The horizontal section of the scope controls the horizontal sweep of the CRT electron beam It causes the beam to sweep at an accurate rate so frequency can be calculated from the sweep time The trigger section of the scope controls how the beam is synchronized with the incoming signal to cause the waveform to be stable The display section of the scope controls brightness focus etc The scope has controls to allow adjustment of vertical sensitivity vertical and horizontal beam position etc The AC DC switch allows the display of either AC or DC signals The function generator typically provides a sinusoidal squar2. Output Function Generator Ground O Ground clip Fig 1 8 Measuring AC voltage Set the function generator to 100 Hz Now adjust it to display one then two and then four cycles of signal What were your horizontal time base settings Use the trigger controls to cause the waveforms to move and then to be stationary synchronized Set signal generator to any frequency Set the vertical attenuator to 0 5 V cm Be sure the vertical attenuator vernier control is in the CAL position Measure the voltage of a 1 1 5 and 2 V peak to peak p p signal Connect the function generator to one of the inputs of the oscilloscope Set the vertical attenuator to 10 V cm and AC DC switch to DC position Switch the function generator on and pull out its DC OFFSET control knob then turn slowly CW positive volts or CCW negative volts What do you observe 25 Khalil Ismailov 15 16 17 18 26 OSCILLOSCOPE INPUT BNC Socket BNC plug FUNCTION GENERATOR 50 OUTPUT Ya Push and rotate Fig 1 9 BNC BNC lead Flip the AC DC switch to AC What happens Set the function generator to a 2 kHz sine wave On the oscilloscope set the VOLTS DIV switch to 1 V the Trigger to positive slope and the time base to 0 1 ms Div Adjust the output voltage of the generator until you get a nicely sized sine wave on the screen Record the waveform in Fig 1 10 Set the Trigger to negative slope and
3. 10 mA 0 01 A A shock of sufficient intensity to cause involuntary control of muscles so that a person cannot let go of an electrical conductor 100 mA 0 1 A A shock of this type lasting for 1 second is sufficient to cause a crippling effect or even death Over 100 mA An extremely severe shock that may cause ventricular fibrillation where a change in the rhythm of the heartbeat causes death almost instantaneously The resistance of the human body varies from about 500 000 Q when dry to about 300 Q when wet including the effects of perspiration In this case voltages as low as 30 V can cause sufficient current to be fatal 1 voltage wet resistance 30 V 300 Q 100 mA Even though the actual voltage of a circuit being worked on is low enough not to present a very hazardous situation the equipment being used to power and test the circuit i e power supply signal generator meters oscilloscopes is usually operated on 220 V AC To minimize the chance of getting shocked a person should use only one hand while making voltage measurements keeping the other hand at the side of the body in the lap or behind the body Do not defeat the safety feature fuse circuit breaker interlock switch of any electrical device by shorting across it or by using a higher amperage rating than that specified by the manufacturer These safety devices are intended to protect both the user and the equipment Elecrtronics Neat Working Ar
4. use cardiopulmonary resuscitation but only if you are trained in the proper technique 7 f both breathing and heartbeat have stopped alternate between mouth to mouth resuscitation and cardiopulmonary resuscitation but only if you are trained 8 Use blankets or coats to keep the victim warm and raise the legs slightly above head level to help prevent shock 9 f the victim has burns cover your mouth and nostrils with gauze or a clean handkerchief to avoid breathing germs on the victim and then wrap the burned areas of the victim firmly with sterile gauze or a clean cloth 10 In any case do not just stand there do something within your ability to give the victim some first aid Khalil Ismailov INSTRUCTIONS FOR ELECTRONICS LABORATORY Organization The laboratory work is a group activity Students will be divided into groups of two or three All members of a group are expected to be present and participate in conducting an experiment with as much equal contribution as possible All members of a group are expected to come prepared and complete the work within the scheduled laboratory period with their laboratory partners No individual member and no individual group will be allowed to do an experiment outside the scheduled times except under extenuating circumstances and only with the consent of the instructor Purpose and Procedure The purpose of this course is to cultivate in the student a degree of independence in c
5. you should refer to the user s manual of the oscilloscope Elecrtronics Connecting the oscilloscope to the circuit under test The input impedance of an oscilloscope is rather high being on the order of 1 MQ which is desirable for measuring voltages in high impedance circuits The attenuator sets the sensitivity of the oscilloscope in the common 1 2 5 sequence As an example the input attenuator could provide for 10 20 50 100 200 mV etc per centimeter The input attenuator must provide the correct 1 2 5 sequence attenuation while maintaining a constant input impedance as well as maintaining both the input impedance and attenuation over the frequency range for which the oscilloscope was designed The oscilloscope is connected to the circuit under test by means of a probe or set of probes as illustrated in Fig 1 3 The probe includes a measurement tip and a ground clip and connects to the oscilloscope by a BNC connector via a flexible shielded cable which is grounded at the oscilloscope This ground serves as the reference point with respect to which all signals are measured The shield helps guard electrical noise pick up Voltage Measurements A screen is divided into centimeter divisions in the vertical and horizontal directions The vertical sensitivity is provided or set in volts cm while the horizontal sensitivity is provided or set in time s cm The magnitude of the signal can be determined from the following equ
6. Me de mer yv Na TROGLA SOURCE s E ODU e C 4 OG OG 90 X 22 05910504 5370 204 e Min N Fig 1 1 Cathode Ray Oscilloscope The heart of the oscilloscope is the cathode ray tube which generates the electron beam accelerates the beam to a high velocity deflects the beam to create the image and contains the phosphor screen where the electron beam eventually becomes visible The electrons are called cathode rays because they are emitted by the cathode and this gives the oscilloscope its full name of cathode ray oscilloscope CRO or cathode ray tube CRT oscilloscope Fig 1 2 The electron beam emitted by the heated cathode at the rear end of the tube is accelerated and focused by one or more anodes and strikes the front of the tube producing a bright spot on the phosphorescent screen The electron beam is bent or deflected by voltages applied to two sets of plates fixed in the tube The horizontal deflection plates or X plates produce side to side movement As you can see they are linked to a system block called the time base This produces a sawtooth waveform During the rising phase of the sawtooth the spot is driven at a uniform rate from left to right across the front of the screen During the falling phase the electron beam returns rapidly from right or left but the spot is blanked out so that nothing appears on the screen Although the oscilloscope can eventually be
7. in the ranges of interest Check all diodes and transistors with an ohm meter Make sure resistors and potentiometers are close to the indicated value Make sure that capacitors are not shorted nor opened In case of equipment failure keep the malfunctioning equipment on your bench do not swap equipment from other benches Equipment sets are assigned to groups Do not attempt to repair malfunctioning equipment Do not even replace fuses Call the lab instructor technician for appropriate action General Tips When something doesn t work as you expect be skeptical about all facets of your design fabrication and test of the circuit Although test equipment may fail from time to time problems are almost always due to errors in design documentation or wiring faulty components occasionally or a misunderstanding of how to use the test equipment In the laboratory the experimenter interacts with natural phenomena which tend to be brutally honest and unforgiving in evaluating a poorly thought out experiment Group interactions can be difficult but Engineering is inherently a discipline requiring much team effort Thus the skills developed in working effectively in a grouped environment are quite important It is the responsibility of each student to create an effective group where everyone contributes substantially Elecrtronics OSCILLOSCOPE and FUNCTION GENERATOR OPERATION OBJECTIVES To understand the operation and use of an osc
8. record the waveform in Fig 1 11 The peak to peak voltage is V Set the frequency of the generator to 500 Hz and change the time base to get 2 cycles on the screen actually a bit more than two Record the waveform and the time base setting in Fig 1 12 Set the waveform of the generator to square wave and complete Figs 1 13 and 1 14 Elecrtronics i inin z kalla ee S Pl SEP ME ed Volts Div Time base Volts Div Time base Fig 1 10 Positive trigger Fig 1 11 Negative trigger HEHEHE H HH H Volts Div Time base Fig 1 12 Waveform recording HHH HHH HHHH HHH HHH HH Volts Div Time base Volts Div Time base Fig 1 13 Positive trigger Fig 1 14 Negative trigger 27 Khalil Ismailov 28 QUESTIONS Is the time base setting important when you are measuring direct current Explain How the magnitude of the signal is determined when you take measurements of voltage from the screen If the vertical sensitivity is increased it takes more signal to deflect the beam true false Answers to Self Test To make the beam sweep across the CRT at a regular predictable rate This in turn allows for accurate frequency measurements If t
9. volt DC signal Time Period Measurements Time is shown on the horizontal X axis and the scale is determined by the TIMEBASE TIME DIV control The time period often just called period is the time for one cycle of the signal The frequency is the number of cycles per second frequency 1 time period V Fig 1 4 Measurement of voltages on an oscilloscope Ensure that the variable timebase control is click stopped fully clockwise before attempting to take a time reading Time distance in cm x time cm For example if time period 4 0cm 5 ms cm 20ms then frequency 1 time period 1 20ms 50 Hz Elecrtronics Functional descriptions of an oscilloscope OS 5020 Coupling AC GND DC Permits selection of coupling of the input channel When set to DC the entire signal AC plus any DC components is displayed When set to AC DC signals are blocked by a capacitor and only AC is displayed When set to ground the input channel is isolated from the input source and is grounded internally VOLTS DIV This is the scope s vertical sensitivity control It is a calibrated control that establishes how many volts each major vertical scale division represents For example when it is set for 1 V DIV each grid line represents 1 volt Each channel has its own independent VOLTS DIV control CAL This is the fine adjust control usually located in the inner of the VOLTS DIV knob When this kn
10. Khalil Ismailov ELECTRONICS LABORATORY MANUAL ort UN m ck TALS CAN Qafqaz University Press Press No 45 Khalil Ismailov Khalil Ismailov ELECTRONICS LABORATORY MANUAL SLN Dm lt Ry YA al 2 ei yc AN gt Oafgaz University Press Baku 2011 ELECTRONICS LABORATORY MANUAL Prepared by Reviewed by Reviewed by Design Kh A Ismailov Professor Department of Computer Engineering Qafqaz University A Z Melikov Professor Associate Member of the National Academy of Sciences of Azerbaijan Republic The Institute of Cybernetics of the National Academy of Sciences of Azerbaijan Republic A Z Adamov PhD Department of Computer Engineering Qafqaz University Sahib Kazimov Is printed as a publication of Qafqaz University by the proposal of the Publishing Committee dated from 06 12 2010 minute No 7 and decision of the Senate dated from 15 12 2010 minute No C QU 15000 000 100 Book is printed by Sharg Garb Publishing House Tel 994 12 374 83 43 374 75 62 Copyright Qafqaz University 2011 Copyright O Khalil Ismailov 2011 Qafqaz University Press No 45 Baku 2011 CONTENTS FME Ge 5 H ee 6 Introduction essent terrent 5 Current Hazards and Voltage Safety Precaut ons sss 6 Meat Working Rea 7 In Case of Electrical BROCK sss 7 INSTRUCTIONS FOR ELECTRONICS BB
11. L Control Mid rotation SLOPE Switch Button out 2 Press the POWER Switch The POWER lamp should light immediately About 30 seconds later rotate the INTEN Control clockwise until the trace appears on the CRT screen Adjust brightness to your liking Turn the FOCUS Control for a sharp trace 4 Turn the CH1 Vertical POSITION Control to move the CH1 trace to the center horizontal graticule line 5 See if the trace is precisely parallel with the graticule line 6 Turn the Horizontal POSITION Control to align the left edge of the trace with the left most graticule line 7 Set one of the supplied probes Fig 1 6 for x10 attenuation Then connect its BNC end to the CH1 or X IN Connector Hook Cover Main Body Retractable Hook Tip Ground Cover Capacitance Ground Clip Correction Trimmer Fig 1 6 Probe Scope probes are available with x1 attenuation direct connection and x10 attenuation The x10 attenuator probes increase the effective input impedance of the probe scope combination to 10 megohms shunted by a few picofarads the reduction in input capacitance is the most important reason for using attenuator probes at high frequencies where capacitance is the major factor in loading down a circuit and distorting the signal When x10 attenuator probes are used the scale factor VOLTS DIV switch setting must be multiplied by ten el Khalil Ismailov Single trace Operation The OS 5020 is set up for single
12. R T R ess 8 Organization wasia wafan sl Purpose and 5 3 Equipment Handling esses 10 HEEN ST PE SEER SERA NERA er sS 10 EXPERIMENT 1 Oscilloscope and Function Generator Operation e 1 EXPERIMENT 2 Diode Characteristics ees 28 EXPERIMENT 3 Half Wave and Full Wave Rectification lt 38 EXPERIMENT H Zener indes ess nh EXPERIMENT 5 Light Emitting Diodes esses 85 EXPERIMENT B Bipolar Junction Transistor sss 78 EXPERIMENT 7 Junction Field EFFect Transistor m EXPERIMENT B Op Amp Characteristics ess 108 EXPERIMENT 8 Linear Op Amp Circuits 120 EXPERIMENT 10 Electronic Hobby Circuits sees 133 REFERHILEB ee ee 168 APPENDIX A Important electrical units abbreviations and symbols 169 APPENDIX B Using the Metric System to Help Some Familiar Metrics a 170 APPENDIX C Resistor Color Coding eese mn APPENDIX D Capacitor Color Coding sss 173 APPENDIX E General Purpose and PIP 174 APPENDIX F JFET Transistors 177 PREFACE The experiments in this laboratory course are designed to cover the theoretical and analytical materials in Electronics Each experiment begins with a set of stated objectives text references and required equi
13. arrying out an engineering task The burden and reward of success is the student s not the instructor s The student will perform specific electronic experiments as indicated by handouts for each experiment These handouts are generally specific but leave much room for independent approaches In the lectures background and motivating material and a certain degree of guidance for the experiments will be given but the exact experimental set up or diagrams will not be given This is the responsibility of the student The instructor or the teaching assistant of the laboratory session may give a moderate degree of specific guidance mainly by asking the student pertinent questions to direct the student onto a correct path He will do this only after the student has demonstrated substantial serious effort to solve the problem The student should not expect to receive from the lab instructor exact circuit diagrams The instructor will however point out errors in diagrams or hook ups as far as this can reasonably be done The grade given to the student for the experiment will partly depend on the degree of independence of the student If everything else fails the instructor will provide a good diagram but this will be done at a severe penalty in the grading Contrary to popular belief most of the work must be done by the student before he or she comes to the laboratory One should study the problems using common sense and any required textbooks an
14. ation Signal voltage V voltage sensitivity V cm x deflection cm If a particular signal occupies 6 vertical centimeters and the vertical sensi tivity is 5 mV cm signal voltage Vs 5 mV cm 6 cm 30 mV Signal to be measured O Probe Circuit under test Ground clip Fig 1 3 Connection of the oscilloscope to the circuit under test Sometimes an attenuator probe is used to expand the range of the scope This probe has a high value resistor in it which acts as a voltage divider with the scope input resistance As a result whatever voltage is read on the scope 15 Khalil Ismailov graticule must be multiplied by 10 Such a probe is called a times 10 or x 10 probe The simplest AC signal is the sine wave and you should use this function as your first AC source When this signal is connected to the oscilloscope you can see that you can easily measure the peak AC voltage Vp which is defined as the voltage measured from the center or zero position to the peak see Fig 1 4 There are several other voltages that can also be measured The peak to peak voltage Vp is the voltage measured from the crest of one cycle to the bottom trough of the cycle or peak to peak Finally the most common voltage is the rms or root mean square voltage Vims It is equal to the peak to peak value divided by 2 x 1 414 For the sine wave only VEN ADENIN e A one volt rms waveform has the same heating value as a one
15. d lmas t rc m olunmas v ya h r hans bir dig r sulla istifad olunmas qada and r d biyyat kimi istifad olunduqda m tl q dipnot g st rilm lidir OK Cancel Kitab n ap olunmu n sx sini ld etm k n Qafqaz Universitetinin kitabxanas v ya m llifl rl laq saxlaya bil rsiniz Contact with Qafqaz University Library authorities or book authors to obtain a copy of the printed book Unvan AZ0101 Xirdalan sohori Hoson liyev k 120 Ab eron Bak Az rbaycan Address Xirdalan city Hasan Aliyev street 120 AZ0101 Absheron Baku Azerbaijan Tel 994 12 448 28 62 66 Faks 994 12 448 28 61 67 e mail info qu edu az www qu edu az
16. d or reference books One must prepare a complete procedure for the experimental work including alternatives and must know what components and equipment are needed and allow for substitution if the first choice is not available One must study the Elecrtronics problem before coming to the laboratory so that the general trend of results is anticipated This will make it possible to recognize nonsense results and correct the experimental procedure Unnoticed wrong results will be considered worse than incomplete results in the grading since the theory and the laboratory is available to the student to validate results Each student must have a laboratory manual The manual will contain the preliminary work done as well as the complete work plan for the experiment It will also contain every test and check made all in lab computations modifications of circuit or procedure and results The instructor may examine the work done and grade the preliminary during the lab periods A concise but complete neatly prepared final report for each experiment by each member of the group must be handed in to the instructor within one week after the completion of the experiment It is expected that the circuits design calculations and data to be the same for two reports written by the members of the same group But this cannot be used to justify near identical reports to be submitted Particularly discussions comments conclusions and the overall style sh
17. e wave and triangular waveform for a range of frequencies and amplitudes Advanced function generator provides functions of function generator pulse generator and sweep oscillator 19 Khalil Ismailov 1 20 SELF TEST Check your understanding of the introductory information by answering the following questions 1 What is the purpose of the horizontal time base section 2 Why is the AC DC switch setting important when you are making low level AC measurements OY uBR o MATERIALS REQUIRED Oscilloscope OS 5020 The term attenuate means what What are the four sections of the scope What kind of waveforms is provided by the function generator What are the functions of the advanced function generators Variable DC power supply GP 4303TP Function generator FG 8002 PROCEDURE Setting up an oscilloscope Before placing the instrument in use set up and check the instrument as follows Set the following controls as indicated POWER Switch INTEN Control FOCUS Control AC GND DC Switch VOLTS DIV Switch x 5MAG Switch Vertical POSITION Controls INV Switch VARIABLE Controls V MODE Switch TIME DIV Switch VARIABLE Control Horizontal POSITION Control x 10MAG Switch OFF released Mid rotation Mid rotation DC 10 mV x1 Mid rotation Norm Fully CCW CH1 1 ms CAL Mid rotation x1 Elecrtronics Trigger MODE Switch AUTO Trigger SOURCE Switch VERT Trigger LEVE
18. ea A neat working area requires a careful and deliberate approach when setting it up Test equipment and tools should be set out on the workbench in a neat and orderly manner Connecting wires from the test equipment to the circuit under test should be placed so as not to interfere with testing procedures Before power is applied to a circuit the area around the circuit should be cleared of extra wires components hand tools and debris cut wire and insulation In Case of Electrical Shock When a person comes in contact with an electrical circuit of sufficient voltage to cause shock certain steps should be taken as outlined in the following procedure 1 Quickly remove the victim from the source of electricity by means of a switch circuit breaker pulling the cord or cutting the wires with a well insulated tool 2 t may be faster to separate the victim from the electrical circuit by using a dry stick rope leather belt coat blanket or any other nonconducting material CAUTION Do not touch the victim or the electrical circuit unless the power is off 3 Call for assistance since other persons may be more knowledgeable in treating the victim or can call for professional medical help while first aid is being given 4 Check the victim s breathing and heartbeat 5 If breathing has stopped but the victim s pulse is detectable give mouth to mouth resuscitation until medical help arrives 6 If the heartbeat has stopped
19. ely low frequency signals TIME DIV switch set to 1 ms or slower If both channels are displayed in signals of the same frequency set the Trigger SOURCE switch to the channel having the steepest slope waveform If the signals are different but harmonically related trigger from the channel carrying the lowest frequency Also remember that if you disconnect the channel serving as the trigger source the entire display will free run Elecrtronics Setting up a Function Generator Pressing POWER Switch turns on power POWER Lamp light up when power is on Connect BNC end of the clip probe to the OUTPUT 50 Q BNC socket The lead is connected with a push and twist action to disconnect you need to twist and pull Push on of three knobs of FUNCTION Selector to get a desired waveform out of sine wave triangle wave and square wave Amplitude of output signal can be controlled by AMPLITUDE PULL 20 dB knob Maximum attenuation is more than 20 dB when the knob is rotated fully counterclockwise Pulling this knob makes attenuation of 20 dB so the output signal can be attenuated by 40 dB when this is pulled and rotated fully counterclockwise Frequency range Seven ranges 1 0 02 Hz to 2 Hz 10 2 Hz to 20 Hz 100 20 Hz to 200 Hz 1k 200 Hz to 2 kHz 10k 2 kHz to 20 kHz 100k 20 kHz to 200 kHz 1M 200 kHz to 2 MHz is selected by FREQUENCY RANGE Selector Output frequency within the selected range is varied by the Fre
20. ground and center the trace Connect the output of the variable DC power supply to the input of the oscilloscope as shown in Fig 1 7 Trace BBB V Variable DC power supply V Ground clip Fig 1 7 Measuring DC voltage Set the vertical attenuator to measure 0 5 V cm Make sure the vertical attenuator vernier fine adjust control is in the CAL position The AC DC switch should be set to DC Measure the voltage of a 1 1 5 and 2 V source obtained from the variable power supply Connect the probe as in Fig 1 7 and set VIOLTS DIV to 1 V Set the output of the variable DC power supply to 2 V and note the beam deflection on the screen From the deflection compute the measured voltage Fill in the table after doing step 9 Change VOLTS DIV to 2 V set the output of the variable DC power supply to 5 V and note the position of the trace Make similar adjustments and fill in the following table Input Probe Volts Div Setting Deflection Oscilloscope Voltage Value Voltage 2v x1 1V 5V x1 2V 15 V x1 5V 10 V x10 15 V x10 22 5 V x10 Elecrtronics 10 11 Replace the variable DC power supply with a function generator as shown in Fig 1 8 Connect the CH 1 input of the oscilloscope to 50 Q output of the function generator using a BNC BNC lead Fig 1 9 Set input coupling on the oscilloscope to ground and center the trace Change the input coupling to AC Trace Oscilloscope
21. here is any direct current on the same line with the low level alternating current and the scope is set in the DC position the trace may be detected off the screen To keep the trace on the screen the vertical attenuator must be set so insensitively as to make the low level alternating current immeasurable To make smaller Vertical horizontal sync and display Sinusoidal square wave and triangular waveforms for a range of frequencies and amplitudes Function generator pulse generator and sweep oscillator The page at www qu edu az says QAFQAZ UNIVERSITY PUBLICATIONS All rights reserved The publications posted on the official web page of Qafqaz University for the purpose of reading and research No part of this publication may be reproduced translated stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without prior written permission by Qafqaz University When it is used as literature footnote must be indicated The page at www qu edu az says QAFQAZ UN VERS TET N N N RL R Bu n rl rin Az rbaycanda n r h quqlar Qafqaz Universitetin aiddir N rl r Qafqaz Universitetinin r smi vveb s hif sin oxunmas v ara d rma apar lmas m qs di il yerl dirilmi dir Universitetin yaz l icaz si olmadan m lumatlar n n tam n d hiss klind ap edilm si sur tinin xar lmas oxal
22. iliar with the contents of the appendixes early Appendix A covers descriptions of important electrical units abbreviations and symbols Using the Metric System to Help Some Familiar Metrics is provided in Appendix B The information about resistor and capacitor color coding is provided in Appendices C and D Appendices E and F covers product descriptions and pin configuration of general purpose NPN PNP transistors and N P channel FET transistors A list of useful electronics sites is provided in Appendix G Khalil Ismailov SAFETY Introduction The experiments in this manual do not use a voltage greater than 30V or 15V therefore the chance of getting an electrical shock is greatly reduced However all voltages do have the potential to burn materials and start fires to destroy electronic components and present hazards to the person performing the operations Common sense and an awareness of electrical circuits is important whenever you are working on these experiments Before actual work is performed sufficient instruction should be acquired in the proper use and safety requirements of all electronic devices Current Hazards and Voltage Safety Precautions It takes a very small amount of current to pass through the human body from an electrical shock to injure a person severely or fatally The 50 Hz current values affecting the human body are as follows Current value Fffects 1 mA 0 001 A Tingling or mild sensation
23. illoscope To learn to measure DC and AC voltages with the oscilloscope To use an oscilloscope to observe repetitive time varying waveforms To use a function generator to create repetitive waveforms BASIC INFORMATION The Oscilloscope The oscilloscope or scope as it is better known is one of the most versatile pieces of laboratory test equipment Fig 1 1 It is really a type of analog voltmeter with an arbitrary zero It can read DC voltages as an offset voltage and as well as AC voltages by displaying the true wave form Most modern oscilloscopes are capable of measuring AC signals over a wide range of frequencies The heart of the oscilloscope is the cathode ray tube which generates the electron beam accelerates the beam to a high velocity deflects the beam to create the image and contains the phosphor screen where the electron beam eventually becomes visible The electrons are called cathode rays because they are emitted by the cathode and this gives the oscilloscope its full name of cathode ray oscilloscope CRO or cathode ray tube CRT oscilloscope Fig 1 2 The electron beam emitted by the heated cathode at the rear end of the tube is accelerated and focused by one or more anodes and strikes the front of the tube producing a bright spot on the phosphorescent screen T Khalil Ismailov A 2 o z woot ol Tew 5 Minos d ore anon TE SE Ie
24. mailov Trigger Slope Selects whether the scope is to trigger on the positive or negative slope of the trigger source waveform Trigger Mode Modes include AUTO the sweep always occurs even with no trigger present NORMAL a trigger must be present and SINGLE SWEEP a trigger is required but only one sweep results INTENSITY Adjusts the intensity of the displayed beam FOCUS Adjusts the sharpness of the displayed beam AUTO Some oscilloscopes with electronic control are fitted with a button which automatically selects an appropriate timebase triggering mode and horizontal gain Function Generator The function generator is a supply that typically provides a sinusoidal square wave and triangular waveforms for a range of frequencies and amplitudes Although the frequency of the function generator can be set by the dial position and appropriate multiplier the oscilloscope can be used to precisely set the output frequency The scope can also be used to set the amplitude of the function generator since most function generators simply have an amplitude control with no level indicators The model FG 8002 Fig 1 5 is an advanced function generator which provides functions of function generator pulse generator and sweep oscillator including following versatile features Wide frequency range from 0 02 Hz to 2 MHz Versatile waveforms are selectable in sine wave square wave Triangle wave and pulse wave etc
25. ob is turned to the fully clockwise direction it is at the calibrated location the normal position of this knob for the outer knob setting i e the vertical scale of the scope is defined by the VOLTS DIV knob When the CAL knob is turned away from the calibrated position the waveform displayed in the scope will start to be attenuated Vertical POSITION This is the vertical position control Each channel has its own control It moves the trace up or down for easier observation It is not calibrated Channel Select Permits displaying CH1 CH2 both channels their sum or difference Timebase V MODE This is a calibrated control that selects how many seconds each major horizontal division represents It is calibrated in s ms and us One control handles all channels There is also CAL knob for the time base The CAL knob is located at the inner of the TIME DIV knob Its operation is similar to that of the previous one for the VOLTS DIV Magnification For both CAL knobs of the VOLTS DIV and TIME DIV the CAL Knob also acts as the magnification switch The magnification is x5 or X10 with the knob pulled out Horizontal POSITION Positions the trace horizontally One control handles all channels Trigger Source Selects the trigger source e g CH1 CH2 an external trigger or the AC power line Trigger Level Permits you to adjust the point on the trigger source waveform where you like the triggering to start T Khalil Is
26. ould reflect individual contribution and originality A good presentation is clear concise and informative It makes good use of graphics has good writing style and presents ideas in a nice logical sequence Some longer experiments will be allowed to be completed in two weeks A quiz may be given at the beginning of each experiment The instructor will give some overall guidance at the beginning The work plans will be checked in the laboratory and graded In summary the student s endeavors will include 1 Preparation of work plans for each experiment based on independent reading and analysis and lecture suggestions 2 Preparation for and taking of lab quizzes Note that preparation of a good work plan will aid in quiz preparation 3 Conducting of the actual experiments in the laboratory 4 Preparation of a final report for each experiment Grading Grades will be assigned over the following categories with the indicated weights approximately Lab reports 25 Preliminary work design 50 Experiment and participation 25 Discussions Conclusions NO LAB EXPERIMENT OR ITS REPORT MAY BE SKIPPED LATE REPORTS LOSE 50 PER WEEK COMPOUNDED Khalil Ismailov Equipment Handling Never take for granted that the equipment or components are in good condition Always check all equipment before you start the experiment Make certain the power supply has ripple free output voltage and that the oscilloscope has the correct gain
27. pment followed by a procedure for meeting each objective The objective of the experiments is to enhance the students understanding of important analytical principles developed in this course by engaging them in the real world application of these principles in the laboratory In addition to further develop the students laboratory practice for experimentally testing and evaluating electrical circuits Preparing the lab is very important as it will save time and allows working more efficiently The pre lab includes reading the lab assignment in advance and doing the pre lab assignment specific to each lab experiment All pre lab assignments have to be handed in with the main lab report at the beginning of the class The manual is designed as an individualized learning package and involves the student in the activities of learning Many illustrations and line drawings are used to familiarize the student with circuit recognition and analysis since this is an important part of being a good electronics technician Each unit follows the same format so that the person using the book can become accustomed to the learning procedure The basic experiments are given on how to test the device and verify its theory of operation Fill in questions are given at the end of each experiment to emphasize the important points gained from performing the experiment This manual contains several appendixes at the end The students is encouraged to become fam
28. quency Dial potentiometer Sweep width is controlled by SWEEP WIDTH PULL ON Control Pulling the knob selects internal sweep and rotating it controls sweep width Rotate it counterclockwise to get a minimum sweep width 1 1 and rotate it clockwise to get a maximum sweep width 100 1 To get a maximum sweep width set the frequency dial to minimum scale below 0 2 scale Sweep rate sweep frequency of internal sweep oscillator is controlled by SWEEP RATE Control Symmetry duty cycle of output signal waveform within range of 10 1 to 1 10 is controlled by SYMMETRY Control The DC OFFSET control knob may be used to offset the waveform above or below ground 0 volts by a DC voltage in the range 10 volts To adjust the DC level pull out the OFFSET control knob then turn slowly CW positive volts or CCW negative volts If the OFFSET knob is pushed in there is no DC level but only AC voltage exists in the output signal Measurements Plug the power cable of the oscilloscope into the socket outlet in the bench Practice setting up the scope to get a trace on the screen Move the trace around Work with all the controls until you understand their functions 23 Khalil Ismailov eh Rotate the focus and intensity controls to get a sharply focused trace at a comfortable viewing level Connect a probe to CH1 and set the channel selector to CH1 and use a x1 probe Set the TRIGGER to AUTO Flip the AC GND DC coupling switch to GND
29. s connected directly to the amplifiers the scope trace moves on the scale an amount equal to the voltage applied If this voltage is a high voltage say 100 V the vertical attenuator must be set to an insensitive position in order for the trace not to be deflected beyond the viewable portion of the screen With the vertical sensitivity thus set a small AC signal on the same wire could not be measured when the vertical input switch is in the AC position a capacitor blocks the direct current from reaching the amplifiers With the direct current blocked the vertical sensitivity can be set so the AC signal can be easily seen and measured The Y amplifier is linked in turn to a pair of Y plates so that it provides the Y axis of the V t graph The overall gain of the Y amplifier can be adjusted 13 Khalil Ismailov using the VOLTS DIV control so that the resulting display is neither too small nor too large but fits the screen and can be seen clearly The vertical scale is usually given in V DIV or mV DIV The trigger circuit is used to delay the time base waveform so that the same section of the input signal is displayed on the screen each time the spot moves across The effect of this is to give a stable picture on the oscilloscope screen making it easier to measure and interpret the signal Changing the scales of the X axis and Y axis allows many different signals to be displayed Sometimes it is also useful to be able to change the po
30. sitions of the axes This is possible using the X POS and Y POS controls For example with no signal applied the normal trace is a straight line across the centre of the screen Adjusting Y POS allows the zero level on the Y axis to be changed moving the whole trace up or down on the screen to give an effective display of signals like pulse waveforms which do not alternate between positive and negative values A dual trace oscilloscope can display two traces on the screen allowing you to easily compare the input and output of an amplifier for example The dual trace oscilloscope provides for amplification and display of two signals at the same time thereby permitting direct comparison of the signals on the CRT screen measure the phase displacement of two waveforms and so on Front Panel Controls Front panel controls permit you to control the operation of the oscilloscope They may be grouped functionally as Main Oscilloscope Controls According to Function Display Vertical Horizontal Triggering Intensity Coupling AC Ground DC Time base Sec Div Coupling Focus Volts Div X position Source Beam Finder Y position Magnification Level Channel Select Cal Calibrated Slope Magnification Mode Cal Calibrated The above function set is summarized for a typical oscilloscope only The oscilloscope in the laboratory that you will be using may have more functions For detail operation of the oscilloscope
31. trace operation as follows 1 Set the following controls as indicated below Note that the trigger source selected CH1 or CH2 SOURCE must match the single channel selected CH1 or CH2 V MODE POWER switch ON pushed in AC GND DC switches AC Vertical POSITION controls Mid rotation VARIABLE controls Fully CW V MODE switch CH1 CH2 VARIABLE control CAL Trigger MODE switch AUTO Trigger SOURCE switch VERT Trigger LEVEL control Mid rotation Use the corresponding Vertical POSITION control or to set the trace near mid screen Connect the signal to be observed to the corresponding IN connector and adjust the corresponding VOLTS DIV switch or so the displayed signal is totally on screen CAUTION gt Do not apply a signal greater than 400 V DC peak AC Set the TIME DIV switch so the desired number of signal cycles are displayed Adjust the Trigger LEVEL control if necessary for a stable display If the signal you wish to observe is either DC or low enough in frequency the AC coupling will attenuate or distort the signal So flip the AC GND DC switch or to DC Dual trace Operation Dual trace operation is the major operating mode of the OS 5020 The setup for dual trace operation is identical to that of single trace operation with the following exceptions 1 eg Set the V MODE switch to either DUAL Select ALT for relatively high frequency signals TIME DIV switch set to 0 5 ms or faster Select CHOP for relativ
32. used to display practically any parameter the input to the oscilloscope is voltage In this way the time base generates the X axis of the V t graph The general laboratory oscilloscope can accept as low as a few millivolts per centimeter of deflection up to hundred of volts using the built in attenuator and external probes 12 Elecrtronics Time base waveform TIME DIV X POS Spot move AA YA JAA 7 Spot blanked out during flyback Time base CH1 SIGNAL INPUT Cathode ray tube Signal waveform Electron SCREEN beem VOLTS DIV Y POS Fig 1 2 Cathode Ray Oscilloscope block diagram The slope of the rising phase varies with the frequency of the sawtooth and can be adjusted using the TIME DIV control to change the scale of the X axis Dividing the oscilloscope screen into squares allows the horizontal scale to be expressed in seconds milliseconds or microseconds per division s DIV ms DIV us DIV Alternatively if the squares are 1 cm apart the scale may be given as s cm ms cm or us cm The vertical input also will have a switch for AC or DC input signals When the AC DC switch is in the DC position the probe is connected directly to the Y amplifier When the switch is in the AC position there is a coupling capacitor between the probe and the amplifiers The reason to allow the measurement of low level AC signals which may be on the same wire as a high level DC voltage If the probe i
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