Physics 115 Electronics and Instrumentation Laboratory Manual
Contents
1. 100 I would like you to perform the calculations using the formula node AND with the graphical wiring of functions Plot the results of each method Calculate the difference between the two values for each value of x and display the average and standard deviation of them Name it yes you guessed it project4 vi Build the VI described in the document peakdetect pdf on my website Actually you will only be graded on the content thru the end of page 7 Adding the markers on the graph is strictly optional Some of the icons have changed since this document was first put together so read them carefully Data files are available on my website spectral txt spectra2 txt hydrogen txt 36 Lab X LabVIEW DAQ Projects Introduction We will be building several projects using DAQ cards and LabVIEW We will be using LabVIEW to input and output data in several ways single point waveform N samples and continuous We will be using the DAQ Assistant to configure the channels The DAQ Assistant is an Express VI that asks what type of data to collect or output on which channel and the kind of collection or output After the options are configured the VI compiles the appropriate code to handle what you ve requested but it keeps this stuff hidden from you It simplifies things but also takes away some flexibility when trying to optimize performance Fortunately for the kinds of things we re interested in it won t be an issue Proje2. The circuit below is a simple and moderately useful probe 330 Q Test Point 5 V LED What is the purpose of the 1 kQ resistor connected to the test point What would happen if it were removed In your write up describe to me why this circuit works Use a logic probe I d suggest one of the real ones to produce truth tables i e verify that they do what they are supposed to do of a NOT gate inverter a NOR gate a NAND gate and one complex gate of your own design Throwing switches can cause problems in digital circuits Because you want to make sure that a there is no noisy turn on and b you must avoid undefined states while the switch is being thrown The bounceless switch shown below resolves these problems Output 5 V 5 V 2 KQ I 2 kQ Use a wire as the switch Describe the action of this switch using your logic probe to test the output Use what you ve learned about digital logic to explain to me in your 27 report why this circuit works the way it does You may want to keep a version of the bounceless switch on your bread board for the next few weeks as there are several opportunities to use it Use the 555 timer data sheet online in its astable mode to build an oscillator operating at 10 kHz with a duty cycle of about 30 Observe the output waveform on the oscilloscope When you ve got it working hook the output up to a speaker and frustrate your laboratory neighbors Note for reasons not
3. no pin Cathode g no pin Cathode c Cathode 1 h d p Cathode r h d p Cathode e Cathode d The lettering of the individual LEDs is industry standard and allows fairly easy interchange of components The MAN 72 does not have any internal resistance in series with the LEDs so you MUST have a small series resistor each cathode and the decoder output Resistors of value 400 700 Q will suffice This prevents the forward bias current from getting to high and burning out the LEDs Connect the 7447 decoder according to the datasheet and connect to the MAN 72 Set the logic state of the inputs for the 7447 by wiring them to ground and 5 V Can you count from 0 0000 to 9 1001 in binary What happens if you put binary values that are larger than 1001 Don t break this down you ll need it in a later part of this experiment Note that the MAN 72 is a common anode type display That means that the LED elements will light when the cathode goes to LO logic If you want to see this in action use a logic probe to test the logic going into the MAN 72 This implies that you need to have a decoder specifically for common anode displays when using a MAN 72 or related display Common cathode displays require decoders intended for them also Can you figure out a way to get the 7447 to blink on and off Build a Delay Flip Flop DFF from a JK Flip Flop Verify the truth table for the DFF The data sheet for the JKFF in the Appendix
4. It is limited to less than 30 kHz signals and should not be used as a primary source We also have a classroom set of WaveTek function generators The WaveTek produces frequencies from lt 1 Hz to 2 MHz DC offset voltages may be applied to all of the previously listed waveforms The square wave also has a variable duty cycle The WaveTek also has a TTL output jack for digital timing purposes Lab I Basic DC Circuits Introduction This set of experiments will introduce you to some basic DC circuits and give the chance to get some experience using the meters and the breadboards Procedure 1 Measure the internal resistance Rm of an analog ammeter a Build the following circuit R is a decade resistance box select one that has a resolution of 0 1 Q or less Set the initial resistance of the box to its largest value b Measure the ammeter current c Reduce Ra until the ammeter current drops to one half the initial value The ammeter resistance now equals Ru d In the write up indicate the internal resistance Rm and prove why this method works 2 Measure the series resistance Rg of a 9 V battery a Build the following circuit using the same decade box as above 9V R b Start with the decade box at near infinite resistance Measure the voltage on the DMM c Decrease resistance until the DMM reading falls by one half The value of the resistance at this level is Rs d Report the battery s internal r
5. VI that will collect waveforms on two channels The waveforms should have a sample rate of 50 kS s and collect for three seconds Use the Signal Manipulation Palette to convert the data from the DDT data type to a 2D array of scalars with each column representing a channel Plot the channels using the Waveform Chart On your prototyping board build a low pass filter with a capacitor and resistor with a cutoff frequency of about 100 Hz Using the built in function generator power the 37 circuit with a sine wave Use your new VI to record the input and output simultaneously for several different frequencies Save your VI as DAQ3_name vi Build a VI that acts like a strip chart recorder by using the continuous collection option A strip chart recorder is a device that was once very common in laboratories A piece of paper rolled under a pen that moved as the input voltage changed This allowed researchers to record voltage changes as a function of time Put a waveform chart inside of the while loop that the DAQ Assistant creates for you to display the data as itis collected As you configure the DAQ the number of samples field indicates that number of samples that will be sent to the software from the buffer at one time The bigger this number the blockier the data comes out Have the DDT data converted to a 1D array Save the entire set of data by appending concatenating the most recent output data to the past data by using a shift regi
6. Website www ni com academic students Many of you have experience in programming computers so I will not spend time discussing data types in class I will spend only a little bit of time discussing the different kinds of structures that you will encounter If you have any questions about them please see me or find resources on National Instruments website or elsewhere If you don t understand the different kinds of data you encounter in programming you will never get a very good handle on what the programs are supposed to do The main idea behind LabVIEW is to create measuring and analysis instruments on your computer rather than to purchase individual instruments for these purposes These virtual instruments VI for short are a flexible and powerful way of processing your data Data is typically loaded into the VIs via a data acquisition DAQ card or via another device such as the Keithley 2000 multimeter connected to the computer Once the data is loaded the various analysis tools built into LabVIEW can be used to process and display the results to the user on the monitor LabVIEW VIs are organized in two windows The first is called the front panel It is the user interface Two kinds of graphical elements are placed on the panel Controls are used to input data and flip switches while indicators display results from the program The second window is called the diagram It is the working part of the program Once you
7. happens If you were trying to measure the intensity of the light accurately how would you work around this problem Is there an electronic solution Keep one of your phototransistor circuits built we will use it in the next section 5V TOP VIEW hv e c Vout b no connection 1kQ Photodiode Use a photodiode as a current source for an op amp in a current voltage configuration and observe the response of a flashing LED on your oscilloscope use a 500 Q resistor in series with the LED and drive them with a 0 5 V signal Compare the response speed of the photodiode to that of the phototransistor What is the maximum frequency of a square wave that you have confidence in measuring for both systems Solid State Temperature Thermistor Use an instrumentation amplifier to compare the differences in responses of a solid state temperature sensor LM355 and a thermistor near room temperature 26 Lab VII Introduction to Digital Introduction In this lab you will be building some very basic circuits to familiarize yourself with the behavior of digital electronics You will also be using the 555 oscillator in both the astable oscillator and monostable one shot mode Procedure 1 Logic probes are used to test the logic high low 1 0 T F at points within a digital circuit We have logic probes available for our use but building a very simple one ourselves proves to be a nice exercise in understanding digital circuits
8. have a program working well you may never open up the diagram It is in the diagram that all of the processes that your program does are defined It is organized very much like a flow chart Data moves between different operations along wires The operations can include simple things like adding two numbers together or more complex like finding the frequency components of an arbitrary signal There are several types of data that LabVIEW can handle most are common to all programming languages floating point number numbers with a decimal point integer 33 number no decimal string i e character Boolean True False and array a set of any of the other types of data The waveform is a rather unique format it is an array of data with timing information included A couple of other unusual data types you will come across are clusters 1t is essentially a grouping of several pieces of data to simplify your code it is used when you need to send several different things to the same place dynamic data type this is a fairly new type it is essentially a specialized type of cluster that is used by the Express VIs that were introduced in version 7 1 and path a special string data type that is used for identifying file paths for accessing data files on your computer As you go through the activities feel free to play around with the VI s you build Add extra features make changes to the output have some fun HOWEVER f
9. time in seconds VI to get the time This VI outputs the time in a time stamp data type It can t be directly used in mathematics it has to be converted into a floating point number use the conversion tools in the numeric palate to do this Put the calculations into a while loop that will allow this data to be generated until a stop button is depressed on the front panel You will want to have a delay inside the while loop so that you don t generate data at a ridiculous rate Consider the options for doing the timing carefully one choice is much better than the others The VI should have controls on the front panel for amplitude frequency and DC offset Is there a difference between placing these controls inside or outside of the while loop Name this projectl vi 2 Modify the VI in project one by giving the user the option of adding random noise to the sinusoidal signal This should involve the random number generator You will want to use a case structure to control whether noise gets added or not The noise should cause deviation from the sine wave in either direction and its amplitude should be variable from zero to no more than the amplitude of the sine wave itself Your chart should be modified to display both the noisy signal and the noise Name this project2 vi 3 Create a VI that reads in the 1D spreadsheet file named testfile1 txt that is available for download on my website You can use either the express VI or the re
10. x y graph use the XY Graph Express VI in your VI Write the XY Data file out to a file Save this project as DAQ7_name vi 39 Appendices 40 Appendix A Parts List Discrete Passive Components Assorted Resistors Decade Boxes Assorted Potentiometers Assorted Capacitors 0 1 mH Inductors Discrete Active Components 1N914 Small Signal Diode 1N4001 Small Voltage Rectifier 2N4124 Small Signal NPN Transistor 2N4126 Small Signal PNP Transistor complimentary to 2N4124 2N3904 General Purpose NPN 2N3906 General Purpose PNP complimentary to 2N3906 Assorted Zener Diodes Operational Amplifiers 741 General Purpose Bipolar 411 General Purpose JFET 351 General Purpose JFET 353 Dual 351 356 General Purpose JFET AD547 Precision Op Amp OP177 Top Shelf Precision Op Amp Instrumentation Amplifiers AD524 Precision Variable Internal Gain Instrumentation Amplifier INA101 Precision Variable Gain Instrumentation Amplifier Comparators 311 General Purpose Comparator 339 Dual GP Comparator 711 Quad GP Comparator Timers Oscillators 555 Single Timer 556 Dual Timer 41 TTL and TTL compatible CMOS Logic 7400 74LS00 74HCT00 Quad 2 Input NAND 7402 74LS02 74HCT02 Quad 2 Input NOR 7404 74LS04 74HCT04 Hex NOT 7408 74LS08 74HCT08 Quad 2 Input AND 7410 74LS10 74HCT10 Triple 3 Input AND 7427 74LS27 74HCT27 Tripl
11. Build a Toggle Flip Flop TFF from a JK Flip Flop Verify that the TFF toggles the output as the clock triggers it using one of the logic switches to drive the clock 31 manually Then drive the clock with a 1 kHz TTL signal from your function generator What happens if J K 0 Build a divide by 16 counter using JKFFs Wire the Qa Qg Qc and Qp to the logic indicators on the Protoboard Use a bounceless logic switch to drive the counter Are you counting properly as you keep throwing the switch Drive the input with a 0 5 Hz TTL signal from the function generator and observe the logic display Does the circuit behave differently when using the TTL signal Any ideas why Increase the TTL input to 10 kHz and simultaneously observe the input and Qc on the oscilloscope Sketch the waveforms that you see and explain what you are seeing Wire up a BCD 7 segment decoder 7447 with a MAN 72 display if you didn t leave it on your board Connect the output of the divide by 16 to the inputs on the 7447 and see if you can count in decimal numbers BCD Numbering System As you are aware it is often difficult to handle large numbers in binary code A system has been developed that simplifies the notation used for large numbers Binary Coded Decimal or BCD In this code we use 4 bit words to describe a digital equivalent Each decimal order is independently coded in binary and is offset from the other orders by a space As
12. Physics 115 Electronics and Instrumentation Laboratory Manual Dr William DeGraffenreid Version 6 1 Last Updated July 11 Table of Contents E 3 IT A SA A A A E A TAR 4 Measurement sI ori a E EE as 5 Lab Basic DG Circuits a A A Ra 8 Lab I Basit AO O OU e ASS ias 11 Jiye DEA Od LEA EA E E E E EE AA 15 Lab IV Transistors and Voltage Regulators o oooooccnnconocccnocononnccnncconcnonnccnnncnnnccnnccnononinos 17 Lab Vi Operational Amplis ts 20 Lab VI Instrumentation Amplifiers and Transducers oooonoconccnoconoconcconncnnnnonncnncnnncnncnnnonnos 24 Lab VII Introduction to DIN A iaa 27 Lab VIM Digia AS o A n cs Saku a ude od 29 Lab Aside Introto Lab VIEW imstande ted 33 Lab IX LabVIEW Projects a ias 35 Lab X Cab VIEW DACIPTO li A a s 37 AppendicesAppendix A Parts Dist ind dE dio 40 Appendix A Parts AA A ANA Sia 41 Appendix Br RESTO CO a ais seston 43 Appendix C Operational Amplifiers A A Ga yeas 44 Appendix D Common Data Sheets siccccssinces caracstescrdaannscornevcaricetevncrestdace danesvanteseevarienveesees 45 Introduction Electronics are a part of every modern laboratory Physics chemistry biology and geology all utilize electronic devices to measure and record various phenomena Whether you need to measure temperature light intensity magnetic fields humidity charged particles time or strain all can be measured using readily available transducers The goal of this course is not to turn you into an el
13. a dual input voltage adder with the following behavior Vout V1 V2 2 Use two different DC voltages to verify the behavior of this circuit Also try adding an AC signal to a DC signal b Build the following difference amplifier and verify its behavior Rf Vout V2 Vi Re Ri 20 c Build the differentiator circuit o 50 nF V Observe the input and output with 1 kHz sine triangle and square waves Do your measured values make sense given what you know about the differentiator circuit d Build the integrator circuit 50 nF Observe the input and output with 1 kHz sine triangle and square waves Do your measured values make sense given what you know about the integrator circuit 3 Filters a Build the following low pass filter and measure the gain as a function of frequency 10 kQ O 21 What is the approximate cutoff frequency How does the gain compare to theory b Build the following bandpass filter oS 0 luF 1kQ O V Measure the gain as a function of frequency In your write up determine the theoretical transfer function and compare it to what you observed 4 Peak detector circuit a Build the circuit shown on the next page The output of this circuit is held at the maximum value of the input The output is reset by closing the switch to short the first feedback loop to ground through the 1 kQ resistor In this circuit you may want to use the 353 amplifier because it cont
14. ad from spreadsheet VI on this however the express VI requires a correct file path The advantage for the read from spreadsheet is that if a path isn t given it allows you to browse for the desired file Once the data is loaded display it using an array indicator and graphically Identify and display the following items the number of elements in 35 the array the maximum of the array the average of the array and the standard deviation of the array Also square the individual elements of the array and take the tangent of each element assume the values in the array are in units of degrees Build a 2D array that has three columns the first containing the original data the second the squares and the final the tangent values Export this 2D array to a spreadsheet file and also using the express VI for writing data Both can be opened in Excel or notepad the express VI has a lot more information but can be a bit more challenging to figure out Project3 vi In this VI you will be creating another waveform but this time you will be using a For loop instead of the while we used earlier and you will also get the chance to use the formula node The formula node is used to perform more complex mathematical operations without cluttering the diagram with wires and functions It essentially uses a box of text based code to do the math Build a VI that calculates the following function y sin 0 5 cosas je Do this for x 1 2
15. ains two independent amplifiers 2 x 351 on a single chip NOTE the 353 amplifier does not have the same pin outs as the other amplifiers 22 By varying the input voltage verify the operation of this circuit This circuit is best observed by watching the trace of the input and output signals on the oscilloscope using a 0 5 s div timebase 5 Ideal Diode a Using the sample circuit diagram in your textbook build an ideal diode half wave rectifier and test its behavior 6 Offset voltage compensation a b Cc Build an inverting amplifier with nominal gains of 50 using either a 741 or 411 amplifier By applying a carefully measured voltage of 1 V to the input determine the actual gain of the circuit by measuring the output Now set the input voltage of the amplifier from part a to ground Measure the output voltage Given the gain from a estimate the offset voltage Vos of the op amp How do the values you measure compare to the data sheets Using the manufacturer s instructions modify your circuit so the offset voltage can be cancelled out 23 Lab VI Instrumentation Amplifiers and Transducers Introduction In this lab you will use instrumentation amplifiers to amplify the input of different kinds of transducers We will be using pairs of each because instrumentation amplifiers are best suited for measuring the difference between two quantities The transducer data sheets
16. are located on the electronics resources website Procedure 1 In the last experiment we built a difference amplifier This amplifier while it was simple suffered from low input impedance Zin R1 essentially eliminating one of the best features of op amps A better approach is the three amp difference amplifier The input impedance of this circuit is very high because of the buffers on the inputs but as in the single amp difference amplifier to get the desired gain care must be taken to ensure that the resistors are carefully matched Build this circuit with a gain of 10 Test the circuit by applying known voltages to V and V2 Don t break apart your circuit you will need it for part 3 Vout If R gt 2R Vout V2 Vi 2R4 R3 R4 Build an instrumentation amplifier using the AD524 or the INA101 These chips have the desired high input impedance and the AD524 has several built in gain settings it doesn t come cheap Hook up your chip according to the data sheet instructions for a gain of 10 READ THE DATA SHEET CAREFULLY Verify the gain with known input voltages 24 3 Build each of the transducer systems below Get a feel for how instrumentation amplifiers can work to cancel background signals and to make differential measurements We have laser pointers flashlights and magnets to use in this experiment Transducers Hall Sensors We have several versions of Hall Sensors availa
17. ble the sensors UGN provide a voltage proportional to the magnetic field normal to the a ront face of the sensor At B 0 Vout Vcc 2 The sensitivities are listed on the appropriate datasheet We will use two sensors next to each other front to back Such an arrangement will allow us to measure the AB Ax 1 e the rate of Vee Vout change of the magnetic field The circuit will be as follows GND Vcc Vec Vi V2 Use the ELVIS 5 V supply to power the Hall sensors Move a bar magnet around the pair of sensors and see if the field gradients you observe make sense given what you know about magnetic fields Phototransistors The absorption of light at the base drives a base current in the transistor that is proportional to the intensity of light on the active surface Similar to a traditional BJT when the phototransistor is properly biased the collector current is proportional to the base current The result is the phototransistor has internal gain making it more sensitive albeit at a cost of response speed than photodiodes as we will investigate shortly The circuit is shown below Use the 5 V to power the phototransistor Build two of these circuits and measure the signal as you modify the relative intensity of the light on them and see if your circuit behaves as you expect Use a laser pointer on one of the phototransistors to drive it into saturation i e the base current deviates from 25 linear response What
18. clear to ANYBODY the duty cycle of the 555 is in terms of the percentage of time off Usually duty cycle refers to percentage of time on Use the 555 in the monostable mode and build a one shot with a 2 second long period Trigger the one shot with your bounceless switch see I told you to keep it Use a logic probe and oscilloscope to observe the behavior For the one shot to work properly the trigger must go back to HI logic prior to the end of the one shot pulse so move that wire quickly 28 Lab VIII Digital Circuits Introduction In this lab you will be building some fairly simple circuits to familiarize yourself with digital circuits Static circuits you will be using are encoders decoders BCD seven segment LED decoders You will be building some fairly simple dynamic digital circuits as well including build delay flip flops DFF toggle flip flops TFF and a divide by 16 counter from J K flip flops JKFF Procedure 1 Build a 4 2 encoder That is build a circuit that will put out a specific 2 bit code depending on which of the four possible inputs is selected The truth table and the circuit are shown below Test the circuit to make sure that behaves properly Input Output 1 2 3 4 A B On 0 0 On 1 0 On 0 1 On 1 1 5V 1 kQ resistors Use a wire as the four way switch Does this circuit behave as you expect Do not disassemb
19. cs Laboratory Resource Page Our analog multimeters are the Triplett 630 NS The Tripplett meters can be used to measure AC and DC voltages and DC currents While the controls for the Tripplett meters indicate resistance can be measured we no longer keep batteries in these meters that are required to power the resistance measurements When you make connections you should use the V Q A and common inputs unless you are measuring currents higher than 1 2 A in which case you use the 12A input and the common Oscilloscope The most widely used instrument in the lab is probably the oscilloscope In this lab we will be using the Tektronix Model 2236 This is a fairly advanced analog scope with a number of useful features including a built in period frequency readout We also have a classroom set of Tektronix Model TDS1002 scopes and two high end scopes the TDS 3044B and the DPO 4054 These will only be used sporadically in 115 while the digital scopes are have somewhat more power and flexibility they can also be misleading if you are not familiar with the basics of making measurements with an analog scope User manuals for all digital scopes are available on the Electronics Laboratory Resource Page While the exact operation of oscilloscopes varies widely the most important elements of the front end are basically unchanged While your textbook has a brief section describing the operation and use of oscilloscopes I would also lik
20. cts 1 Build a selectable voltmeter VI On the front panel create a knob that will allow you to select from one of four possible channels 0 3 to sample the voltage at the channel just a single measurement and display it You will want to use a case structure for selecting the channel each case will have a different DAQ Assistant VI in it Have the selected output display on the front panel but only the selected one along with the channel number and the time that the data was collected Save your VI as DAQI name vi 2 Starting with the VI from project 1 use a sequence structure and a waiting while loop to the VI so that when you run the VI no recording is made until you depress a button that you also add called Sample To do this the while loop should run and hold until you press the sample button which then forces the VI to move to the next step in the sequence the data recording Save your VI as DAQ2_name vi 3 The problem with single point acquisition is that the software controls the data collection This can limit the speed of the data collection If the DAQ Assistant is configured to collect a waveform or N samples the system is configured to collect the data at a specific rate for a specific number of samples and collect the data using the built in memory on the DAQ Card the buffer so that you don t have to shuttle configuration information back and forth between the software and the card Build a
21. d Classic 351 JFET 2 5x 10 13 5 411 JFET 2 5x 10 15 0 8 Very good general purpose 353 JFET 2 5 x 10 13 5 Dual 351 356 JFET 5 0x 10 12 3 Higher Gain Additionally we have some higher gain and precision amplifiers available We will probably not use these until project time if at all Op Type Gain Slew Rate Vos typ Comment Amp V us mV AD547 JFET 2 5x 10 3 lt 0 25 Precision amp OP177 Bipolar 1 2 x 10 0 3 lt 0 025 Top shelf precision amp The pin out diagrams for the single unit amplifiers are all basically the same for DIP 8 packages The main differences between the pin outs are the method used to compensate for the offset voltages using the remaining pins 1 5 and 8 Detailed pin outs and data sheets are available for you to use IN V Typically V and V the supply voltages are as 15 V but the op amp will usually operate over a HN OUT much wider range of voltages than this Keep in y mind that the input and output voltages cannot go outside of the range defined by V and V Also keep in mind that in circuit diagrams the connections for V are rarely shown Note that the pins are numbered from the upper left corner as indicated by the notch or a dot at the end 44 Appendix D Common Data Sheets The following data sheets are for your use in this course They are fairly generic data sheets and may not be for
22. e 3 Input NOR 7486 74LS86 74HCT86 Quad 2 Input XOR 7447 74LS47 74HCT47 BCD to 7 Segment Decoder 7474 74LS74 74HCT74 Dual Positive Edge JKFF Optoelectronics Phototransistors Photodiodes Photoresistors Assorted visible and IR LEDs 7 Segment LED Displays MAN 72 and compatibles Photoswitches Reflective and Transmissive 4N31 4N32 Optocoupler 4N37 Optoisolator Transducers AD590 Temperature Sensors LM355 Temperature Sensors UGN3503 Hall Sensors EMD 4000 Humidity Sensors 42 Appendix B Resistor Codes Color Figure Multiplier Tolerance Black 0 1 Brown 1 10 Red 2 100 Orange 3 1000 Yellow 4 10 Green 5 10 Blue 6 10 Violet Y Grey 8 White 9 Gold 107 5 Silver a 107 10 Appendix C Operational Amplifiers We have several kinds of operational amplifiers available to us in this course Additionally there are many different kinds of specialized amplifiers instrumentation amplifiers audio amplifiers low power high speed the list goes on an on Many of the amplifiers are generic By generic I mean that several manufacturers make their own version of the chips but a common number identifies them A summary of the specifications of several common general purpose generic op amps is shown in the table below Detailed sheets are in Appendix D Op Type Gain Slew Rate Vos typ Comment Amp V us mV 741 Bipolar 2x 10 0 5 6 An Ol
23. e to refer you to The XYZ s of Oscilloscopes published by Tektronix one of the leading oscilloscope manufacturers There are several copies of this available for use in the classroom and is also available in pdf format on the Electronics Laboratory Resource Page I suggest that you read this manual before using the oscilloscope Workstations ELVIS Lives The most common tool in 115 is the National Instruments ELVIS workstation These workstations integrate a breadboard prototyping board power supplies waveform generators and computer interface into a single package These features can be controlled via the workstation s front panel or by software on the computers we will generally use the front panel See the Electronics Laboratory Resource Page for the ELVIS User s Guide Breadboards The most convenient way to design and troubleshoot a new circuit is to first design it on a breadboard Breadboards can be of the stand alone variety have built in power supplies we have a large collection of these that might be useful for your projects or may be bundled with additional stuff for easy access like our ELVIS stations and the Protoboards that preceded them All are handy because circuits can be wired up without the use of soldering irons or wire wrapping tools Be careful not to use wires that are too thick for the board Forcing oversized wire into the board may permanently bend the spring contacts leading to poor conn
24. ections no connections or even possible short circuits to other rows We will discuss how to use the board in class Power Supplies We will generally use the built in power supplies that are on the ELVIS workstation or on the powered breadboards So far these supplies have proven to be rather stable sources of DC power The ELVIS workstations have five supplies built into it 5 V 15 V 15 V and variable positive and negative voltages The powered breadboards have 5 V 15 V and 15 V sources Additionally we have other fixed and variable sources available if needed Function Generators We will use Tektronix AFG3022 Arbitrary Waveform Generators to produce the AC signals that we will use in this course These generators will be shared between adjacent groups as they have dual outputs that can be independently controlled It can produce sinusoidal square triangle and many other signals with frequencies up to 25 MHz It can be programmed to produce a certain signal without turning the signal on It has the capability of producing user defined waveforms also We have a couple of high performance Agilent 33120 waveform generators that can produce signals up to 15 MHz These instruments can do the traditional sinusoidal square and triangle waves but can also do sawtooth cardiac exponential decay and user defined waveforms The ELVIS also has a built in function generator that is useful for low frequency applications
25. ectronics whiz Rather it is a survey course that will introduce you to the broad range of electronic devices and techniques that are commonly used in laboratories today While we will spend some time on historical and fundamental devices such as transistors and A D chips we will focus most of our attention on practical and useful devices op amps computer integrated data acquisition cards and specialized integrated circuits ICs Our goal is to instill in you a degree of comfort and familiarity with electronics that will be useful in designing experiments building simple circuits and understanding the behavior of complex circuits By the end of the semester you should be comfortable in developing computer controlled data systems where you have conditioned the signal of interest using your newfound electronic skills and collect the data on the computer using the LabVIEW software package I have chosen not to include much theory in this manual First of all all of the information would be repetitious because the same information will be in your textbook and or lecture notes Second of all I ve tried to prevent this manual from being a self contained cookbook Forcing you to use your notes and textbook will in the end make you more self reliant Some experiments will take a single session others will take two They are however all equally weighted Because the LabVIEW software package is commonly encountered in research and industria
26. esistance and prove why this method works 3 Measure resistance of a lamp a Measure the resistance of a lamp directly using the DMM b Build the circuit below to measure the resistance of a lamp using ELVIS s positive variable supply as the voltage source c Measure the V I characteristics of the lamp Do not exceed 12 V on the lamp The lamp should not be left on at voltages above 6 V for an extended time d Will a lamp work as a resistor in a pinch Plot the I V characteristics and compare to an ideal resistor Discuss your thoughts of the behavior in the write up 4 Voltage Dividers a Design a circuit with the following form Ri Vout Select R and Rz so that they add to 5 KQ within 10 and the gain of the circuit is 0 33 also within 10 You may have to combine resistors to get a system that meets these requirements b Build your design Does it work as you expect c Design and build a variable 5 to 5 V supply using two 9 V batteries and a 1 kQ potentiometer Hint Other components may be required d Show me your working circuit 10 Lab II Basic AC Circuits Introduction The purpose of this experiment is to introduce you to some simple AC circuits These circuits are commonly used to condition electronic signals Examples of conditioning include integrating differentiating and filtering signals Procedure 1 Comparison of Amplitudes a Connect a 100 KQ resistor across the waveform gene
27. h the input and output on the same graph See the note at the end of this paragraph regarding how to measure the output voltage Add a capacitor to the output and observe how the output changes Sketch what you see WARNING You cannot observe the input and outputs simultaneously with this circuit because neither end of the output is at ground To properly measure the output voltage we ll need to take what is called a differential measurement Use channels A 15 and B on the scope to measure the voltages on either side of the load resistor with respect to ground Use the Add and Invert functions on the oscilloscope to display the difference in voltage between the two ends of the load resistor I can bring over our fancy 4 channel scope to really show the entire behavior input and differential output at the same time Build a voltage clamp as we discussed in class with a variable voltage Systematically study its behavior and report what you find in the write up Measure and plot the reverse bias characteristic curve for a Zener diode use one with a Vz lt 5 V as done in part 1 Note the type and V of the diode Build a clipper with two Zener diodes and observe its behavior as you vary the amplitude of the input Where might this be useful 100 Q Vs Bonus experiment if time permits Use the same circuit above to measure the forward biased characteristic curves of at least two different colored LEDs red and green Discuss t
28. he difference Does the light output reflect the I V characteristics 16 Lab IV Transistors and Voltage Regulators Introduction In this lab we will be using the 2N4124 general purpose npn bipolar junction transistor We build several useful circuits We will also observe the performance of an integrated circuit voltage regulator and the effect of feedback on an amplifier Procedure 1 Build the following BJT switch 10 V O From Variable 5 V O The switch is simply a wire that you can insert or remove one end of to make or break the connection between the 5 V source and the 1 kQ resistor Take note of the values of I and Vee for the two cases on off Do these values make sense given what we know about the switch circuit Why 2 In lecture we learned about voltage dividers and the drop PRN in the output voltage that occurs when a low impedance load is connected to it Build a voltage divider with Rj 1 KQ and R3 10 kQ and measure the output voltage Now put a load resistor Ri 8 KQ in parallel to Ro and measure the output voltage Between Ri and R2 Now build the buffer circuit to the right with the base connection going to the output of the voltage divider Measure the voltage across the load resistor Does this R voltage agree with theory a Note such a circuit becomes very useful when interfacing with computers as the data boards generally have low output impedances compared to s
29. in decimal notation leading 0 s are usually not written The numbering systems is as follows Decimal BCD Equivalent 0 0000 1 0001 2 0010 3 0011 4 0100 5 0101 6 0110 7 0111 8 1000 9 1001 10 0001 0000 11 0001 0001 12 0001 0010 43 0100 0011 287 0010 1000 0111 32 Lab Aside Intro to LabVIEW LabVIEW is a software package designed for data collection data analysis and process control It has been around since 1986 it is made by National Instruments known in the business as NI It has become an industry standard serving companies universities and national research laboratories around the world One could study the details of LabVIEW for years and still not be an expert at all of the features that it has My goal is to make you proficient in using existing LabVIEW programs and to develop your own simple programs for data analysis and data acquisition Most semesters we ll try to schedule a campus tutorial for the most recent version of LabVIEW Included in the LabVIEW program is a document called Getting Started with LabVIEW that can be found on its start screen On the Electronics Resources Website there is a PowerPoint presentation produced by NI called LabVIEW in Three Hours that covers many of the basics of LabVIEW It is written for Version 8 but the basics of the program haven t changed Other items for students can be found at NI s Academic
30. l laboratories there is a recommended text in the bookstore that teaches the details of it We also have a couple of copies of the LabVIEW text in the lab to use This manual will also likely serve as a reference for future classwork particularly in Physics 116 Advanced Electronics and Instrumentation I suggest that if you are planning on taking this course you hold onto this book This is the sixth edition of this manual it is mainly for correcting some errors and restructuring some experiments It is only available electronically it is not for sale in the bookstore Safety In general the electronics that one encounters in this class are no more dangerous than those one may encounter upon replacing a 9 V battery in a household electronic device most electronics textbooks do not even discuss safety hazards In fact the biggest risk to ones health in this class is mechanical rather than electrical dropping an instrument or computer on your foot However one must still be careful to avoid exceeding tolerances on all devices Over powered resistors can get very hot very fast and can leave a blister on one s fingers if touched Transistors are famous for popping when improperly wired The shrapnel from one could scratch the cornea of your eye an experience that your contact lens wearing friends will assure you does not feel good While we don t normally solder in this class if you find that you need to make sure you use a pair
31. le your circuit you will use it in part 3 2 Build a 2 4 decoder that will take 2 bit inputs and drive one of 4 lines The truth table and circuit are shown below 29 3 Input Output A B 1 2 3 4 0 0 1 0 0 0 10 0 1 0 0 0 1J0 0 1 0 1 1 0 0 0 1 Wire the inputs to the logic switches to the 5 and GND lines on the ELVIS to select the states of A and B Wire outputs 1 4 to LEDs with resistors as logic indicators or use the build in LED s on your ELVIS Now connect the encoder and the decoder and see if the data properly sent Connect the A B outputs on the encoder to the A B inputs on the decoder Does your action with the switch drive the correct LEDs on the logic indicators Why would two circuits like this be useful Why not just run four wires directly Think about this in terms of needing to send more than four possible signals We will now use one of the more useful chips available the 7447 a BCD to 7 segment LED decoder This is used to drive a 7 segment LED used to indicate numbers on a panel Notes on the BCD numbering system are at the end of the procedure We will be using a MAN 72 or compatible display It is a common device used to display numbers on a panel It is made up of 7 segments that light up to form numbers that a reader can understand Below is a sketch of what the pins and the LEDs look like 30 Cathode a 5 V Cathode f Cathode b 5 V no pin
32. n ideal BJT it has a gain of 100 in actuality it will be closer to 50 without the feedback Use the largest valued capacitors you can find 1 uF Measure the gain as a function of frequency with a sine wave Make sure the amplitude to the input signal is small enough that the output isn t clipped due to the circuit s high gain Also observe the output when driven by a triangle wave Note the frequency when the output triangle is distorted 15 V 1kQ 100Q Add the feedback network a 1 kQ resistor Measure the gain as a function of frequency Again observe the output when driven by a triangle wave At what frequency is the triangle wave distorted 19 Lab V Operational Amplifiers Introduction In this experiment we will be building many different circuits that will demonstrate the usefulness and simplicity of using operational amplifiers Procedure For the first several parts of any of the amplifiers will work It is not until parts 4 and 5 that you will need to be careful of the type of op amp you will be using Because of the high gains of these circuits you need not provide a very large input voltage 1 Amplifiers a Build an inverting amplifier with a theoretical gain of 20 b Build a non inverting amplifier with a theoretical gain of 20 c Measure the gain of these circuits using both AC and DC inputs At what frequency does the gain begin to significantly deviate from theory 2 Mathematical Functions a Build
33. ncy bandwidth transmission maximum change 8 The following circuit is called a notch filter Measure its characteristics In your write up describe a situation where this might be useful 56 Q Vin 0 1 uF Vout 0 1 mH 14 Lab III Diodes Introduction In this lab you will characterize several varieties of diodes and build some basic and useful diode circuits Procedure l Measure the I V characteristics of a 1N914 diode Use the following circuit to measure the voltage Pick a resistor of high power tolerance so that it does not burn up You should be able to use ELVIS s positive variable power supply for the source voltage For the negative bias case use the ELVIS s negative variable voltage as the source Keep an eye on the resistor to make sure that you don t overload it Plot your results for your write up I as a function of V Prepare a second plot focusing on the region where the curve changes the most What is the diode voltage drop in the forward direction Estimate the forward and reverse resistances from this plot Build a half wave rectifier In the write up show me the circuit layout Sketch the input and output on the same graph Hint looking at input and output on the scope at the same time will help this Add a capacitor to the rectifier output How does the output voltage change Again plot the input and output Build a full wave rectifier In the write up show me the circuit layout Sketc
34. of safety glasses Soldering flux or molten solder would be very unpleasant in an eye as Dr DeGraffenreid can attest to However one should not take a cavalier attitude towards electronics There are many cases one will encounter in the laboratory where high voltages are a part of the experiment Care needs to be taken in such a case a current of a few milliamperes through your heart can cause severe problems If you find yourself working on high voltages it is a good practice to have your arm grounded so that if you touch the high voltage with your hand the current won t cross through your body In fact it is a good practice to use grounding straps at all times when working with electronics This is not necessary for your own safety but rather for the safety of the devices you are working with static discharge can be deadly for many semiconductor devices Unfortunately we don t have grounding straps to go around Luckily we use generally inexpensive components If you find yourself using high end components in your final project please ask about borrowing a grounding strip to use Measurement Instruments Multimeters We will normally use benchtop digital multimeters DMM in this course although we do have some analog and handheld digital multimeters available if needed The theory behind multimeters particularly analog meters is very interesting but unfortunately we don t have time to cover it in this course If you are interes
35. or the sake of the students following you please DO NOT WRITE OVER any sample VI s that come with LabVIEW In fact be careful and make sure that you save all your own VI s a unique folder i e D LabVIEW bobandsarah_f09 In the experiments that follow you will be given several projects to build The instructions are to guide you but you are responsible for developing your own code You should submit your VI s to me via e mail after completion along with any other information that is asked for data files comments etc 34 Lab IX LabVIEW Projects Introduction You will be performing the following exercises using LabVIEW Make sure that everyone in the group understands the program Your write up for this week s experiment will be the VIs themselves and the output files that I have asked you to prepare using LabVIEW Send these all to me in a single email You will be graded on whether you completed the asked tasks your program s organization and usability To this end make sure that your VIs are labeled and the default values of controls are reasonable The best way to learn a program is to use it Feel free to come in and play with it We will be using LabVIEW more in the future when we start using computer data acquisition DAQ Projects 1 Build a VI that generates and displays a sinusoidal wave using simple mathematical tools not using the waveform generator that comes with the program You should use the get
36. rator s Tektronix or Agilent output b Using the oscilloscope to measure the output waveform set the generator to a l kHz sine wave with no DC Offset with a peak to peak voltage of 1 V c Measure the rms voltage with the DMM Does this value make sense Why or why not d Repeat with triangle and square waves Do these values of the Vims make sense Why or why not e Replace the Tektronix generator with a WaveTek Examine the waveforms again How do the generators compare to each other Which would you prefer to use in class and why 2 Charging of a capacitor a Build the following circuit using your Tektronix or Agilent generator 100 kQ 2 2 nF b Set the generator to a 400 Hz square wave and adjust the amplitude and DC offset so that the output varies from 0 V to 1 5 V 11 c Measure the voltage across the capacitor C using the oscilloscope Setup the oscilloscope to display both the input and output waveforms simultaneously d Using only the waveforms determine the time constant t the time it takes for the voltage to drop to 1 e the initial value for the circuit How does this compare the theoretical value for the given circuit elements 3 Integrator Circuit a Build the following circuit with a square wave driving signal 100 kQ 7 5 kHz 2 2 nF Vout b Record i e sketch in your notebook the input and output waveforms Does the output make sense Does it vary from the expected val
37. ster and the build array feature See figure below Save your VI as DAQ4_name vi DAG Assistant Design a system that will interface a transducer with a VI PI leave it to you to design what sort of system you want 1 e changing lighting temperature or magnetic fields but the VI should display the information gathered in a clean and relatively calibrated way Think what an end user would want the display to show Save your VI as DAQ5_name vi Design a VI that will write out a voltage of the following form using the output feature of the DAQ Assistant V u t 2 3sin 0 5 Hz 271t 0 5 cos 10 Hz 27t Observe the output on your oscilloscope Save the VI as DAQ6_name vi Design a VI that will allow you to power and monitor a light bulb Use a phototransistor located about 2 from the light bulb to monitor the light intensity coming off of the bulb as your VI steps up the light bulb voltage in 0 25 V steps from 0 to 8 V Save the VI as DAQ4 name vi Use the phototransistor circuit below 38 5V TOP VIEW c O hv eee Vout b no connection The DAQ card will not provide enough current to power the lightbulb so you will have to use a BJT as a power current amplifier 15 V DAQ Out Vout Because of the voltage drop across the BJT also record the voltage across the lamp with your VI so that an accurate intensity versus voltage curve can be obtained Plot the intensity as a function of the voltage in an
38. tandalone power supplies 17 3 Constant current source This circuit produces a nearly constant current through a load resistor connected to the collector The collector current I is controlled by the base current in this circuit Measure the current as you vary the load resistance from 0 to 2 5 kQ Use a decade resistance box for the variable resistor 4 Integrated circuit voltage regulators There are many families of chips used to regulate voltages We will be using the LM340 family These are high accuracy fixed voltage three terminal regulators very closely related to the LM78XX series discussed in the textbook Connect the LM342P5 0 5 0 regulate voltage output as shown below Pin 1 Input 2 Ground 3 Output Use the function generator for the input voltage source you will need to vary the offset voltage For the LM342 to work the average voltage must be 2 V above the regulation value so make sure that the DC offset is set high enough for the regulator 18 to work Observe the input and output on the oscilloscope for different DC offsets sinusoidal and triangular ripple and with varying ripple magnitude What happens if a portion of the input waveform drops below the Vou 2V threshold It makes things easier to observe if Vin and Vout are displayed on the oscilloscope simultaneously Build the following transistor amplifier don t worry too much about the actual design of the circuit just note that with a
39. ted in finding out more information regarding them refer to your textbook There are two models of benchtop Keithley multimeters that we will commonly use in the lab the Model 2000 and the Model 179 A The Keithley Model 2000 will be our primary instrument but for measurements we will also need to use the 179 A The Tektronix Model 2236 Oscilloscope also has a built in multimeter that we might occasionally use for DC voltage measurements The specifications of the primary meters are listed below Model 2000 Model 179A Digits 6 4 Y DCV 0 1 uV 1 kV 10 uV 1 2 kV ACV 0 1 uV 750 V 10 uV 1 0 kV DCA 10nA 3A 10 nA 20 A Rae ACA 1pA 3A 10nA 20A Q 100 uQ 120 MQ 100 mQ 20 MO Frequency 3 Hz 500 kHz NA Input DC 10 GQ 1 MQ Impedance AC 1 MO 1MQ Clearly the Model 2000 is a more precise instrument It can also be computer interfaced via GPIB if desired Its main drawback is its complexity For most purposes 6 4 digits is overkill and just slows down the refresh rate From the front panel you can decrease the number of digits displayed The Model 2000 can only measure currents up to 3 amperes whereas the Model 179A can go up to 20 amperes This isn t usually a concern in this course where we usually work with currents less than 1 ampere Several copies of the Model 2000 user s manual are available for review and it is also available in pdf format on the Electroni
40. the exact manufacturer that we have in stock In fact most of the ICs in stock will be a mixture of brands For more detailed information regarding each chip you may want to visit the manufacturer s web site and download pdf files of the datasheets yourself In this version of this manual the following data sheets are included Device 2N4124 2N4126 2N3958 LM741 LF411 LF351 LF353 OP177 AD524 INA101 LM111 LM211 LM311 LM555 DM74LS00 DM74LS02 DM74LS04 DM74LS47 DM74LS74A AD590 UGN3503 Manufacturer Vishay Semiconductors Vishay Semiconductors Vishay Semiconductors National Semiconductor National Semiconductor National Semiconductor National Semiconductor Analog Devices Analog Devices Burr Brown National Semiconductor National Semiconductor Fairchild Semiconductor Fairchild Semiconductor Fairchild Semiconductor Fairchild Semiconductor Fairchild Semiconductor Analog Devices Allegro Microsystems 45 Document Date 5 2002 5 2002 6 2001 7 2000 7 2000 12 1995 7 2000 2002 1999 1998 1 2001 2 2000 7 1986 5 1986 3 2000 10 1988 7 1986 1997
41. ue c Instead of a square wave try using sine and triangle waves Does this circuit integrate properly Note you may have to get clever with the oscilloscope to do this 4 Differentiator Circuit a Build the following circuit with a square wave driving signal 2 2 nF 20 Hz Vout 100 kQ 12 b Record i e sketch in your notebook the input and output waveforms Does the output make sense Does this vary at all from the expected value c Instead of a square wave try using sine and triangle waves Does this circuit differentiate properly 5 Build the following three circuits Build the circuits so that the cutoff point is in the neighborhood of 75 kHz For each circuit measure the gain over the range 50 Hz 2 MHz Choose your steps carefully fine enough to show details but coarse enough that you finish in reasonable time In the write up do a detailed comparison of the gain curve that you measured to theory Note the general trend of any phase shifts that you observe a High Pass b Low Pass c High Emphasize use same values of C and R as in above Vout 13 6 Build the LRC circuit below Measure the transfer function of this filter What is the FWHM bandwidth of the transfer function 270 Q Vout 0 1 mH 7 For the circuit in part 6 replace the resistor with one that is an order of magnitude higher Measure the characteristic curve How does the response i e central freque
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