SIMULATIONS USING PSPICE & OSCILLOSCOPE TRAINING DRILL
Contents
1. Earth Ground Vdc DC Voltage Source Vsin Sinusoidal Voltage Source Vpulse Square Wave Voltage Source uA741 741 Op amp Exercise At this point you are now ready to begin simulating some simple circuits We will begin by simulating some of the same circuits you have built in the previous labs 1 Simulate the circuits in Figures 5 8 a b and c Make sure to measure all branch voltages and currents Plot results Compare these with the results obtained in the previous labs Are there any significant differences in results If so explain Note Provide separate plots for voltage and current Make sure to label your plots 5 8 b In erting summer 5 8 C 2 Simulate the circuit in Figure 5 9 Notice that the input source is no longer DC Instead we will use an alternating source AC voltage Display both input and output voltages plots on the same graph Do this for both a sinusoidal input Vsin source as well as for a square wave Vpulse source Below are the parameters you need to set the sources to You may change a source s or any parts par parameters by double clicking on the part Vsin Vpulse DC 0 DC 0 AC 5 AC 5 Voff 0 VI 5 Vamp 5 V2 5 Freq 1000 TD 0 TD 0 TR 0 00001m DF 0 TF 0 00001m Phase 0 PW 0 5m PER Im Note Do not skip spaces Figure 5 9 3 Dependent Sources in PSpice There are four different types of dependent sources all which can be found and utilize2. D File Display Help Memory Used HELAI Transient Analysis Time step EENI 1 Time A l SSI End KIN Figure 5 6 Simulation dialog box Once this portion of the simulation has finished results are usually displayed graphically through the use of the Probe interface in Pspice Figure 5 7 presents an example Probe display In the case where your simulation has finished running and you do not see the Probe display go to Analysis gt Run Probe This should work provided your circuit is error free Note Remember to place markers before you run your simulations ld MicroSim Probe Schematic1 Ey File Edit Trace Plot View Tools Window Help lej x Figure 5 7 Sample Probe display 5 Useful Shortcuts Below is a list of frequently used shortcuts These options can be additionally accessed from the available toolbars in the schematic editor lt Ctrl F gt Provides a mirror image of the part by flipping it completely over lt Ctrl G gt Displays the Get New Part dialog box lt Ctrl P gt Selects Get Recent Part list box lt Ctrl R gt Rotates selected part in increments of 90 lt Ctrl T gt Creates a text box lt Ctrl W gt Places wire 6 Basic Parts List Pspice provides an extensive parts list Its libraries may contain thousands of components In order to simplify your searCH Below is a list of basic parts that you may need for the course of the semester R Resistor C Capacitor L Inductor egnd
3. RMS voltage of the selected input signal The units for this measurement are volts This indicator is visible only when measurements are turned on Frequency Displays the reciprocal of time between adjacent mid reference level crossings in the same direction period of the selected input signal The units for this measurement are Hertz This indicator is visible only when measurements are in progress V gt p p Displays the difference between the highest and lowest measured voltage level of the selected input signal The units for this measurement are volts This indicator is visible only when measurements are turned on C1 Voltage Displays the corresponding voltage level of the selected channel trace at the current cursor position The units for the measurement are volts This value is visible only when cursors are turned on C2 Voltage Displays the corresponding voltage level of the selected channel trace at the current cursor position The units for this measurement are volts This value is visible only when cursors are turned on dT Displays the difference in time between cursors C1 and C2 The units for this measurement are seconds This value is visible only when cursors are enabled II Introduction to the ELVIS Function Generator 1 Start the ELVIS function generator by selecting Function Generator from the NI ELVIS command console The following interface should be displayed on the desktop I NI ELVIS Function Gene
4. SIMULATIONS USING PSPICE amp OSCILLOSCOPE TRAINING DRILL In this experiment the student will explore circuit simulations using MicroSim s Pspice followed by an oscilloscope training drill using Virtual Bench Pspice Tutorial L Launching the schematic editor The schematic editor interface to PSpice may be either be launched from the desktop or from Window s start menu It can be found in Start gt Programs gt MicroSim Pro 8 gt Schematics Below is a figure of the Schematic editor interface ES MicroSim Schematics Schematic p 1 8 File Edit Draw Navigate View Options Analysis Tools Markers Window Help x pojem s Hele aA Aee ssla 7 ala rik None PIAJ v I S B Y 4 b 2 47 0 00 Cmd Figure 5 1 MicroSim Schematics editor a Placing Parts MicrSim s schematic editor describes several ways of selecting and placing parts Two of these options are available from the toolbar If the user knows the name of the part in question it may be directly accessed from empty text field in the toolbar This is known as the Get Recent Part list box This field not only allows the user to select new parts but it also keeps track of recently used parts for quick access Below is a figure of the parts and wire toolbar where this option may be found Figure 5 2 Parts and wire toolbar In addition to this PSpice keeps an extensive parts library from which the user can
5. UT The two signals CAN NOT be active simultaneously you must choose one output or the other Also please note that some of the built in functions WILL NOT WORK if DACO is used as the input III Exercise 1 1 Set the Oscilloscope Controls to the following e DC Coupling e OV Offset e Trigger Immediate 2 Complete the following steps to measure a signal with the NI ELVIS Scope SFP 1 Connect the signal s you want to measure and the trigger signal if desired to the BNC connector s on the front of the NI ELVIS Benchtop Workstation or to the corresponding inputs on the NI ELVIS Prototyping Board ll Launch the NI ELVIS Scope SFP from the NI ELVIS Instrument Launcher Refer to Launching the SFP Instruments for more information ill The NI ELVIS Scope SFP starts running when launched You should see the signal in the Display Window IV If needed adjust the Trigger Source control to stabilize the signal in the Display Window If you have an external signal connected as the trigger signal select SCOPE Trigger If you want to use one of the input channels as the trigger select CHANNEL A or CHANNEL B from the Source control V Adjust the Timebase Vertical Position Scale and other controls as desired You should now be able to read data on both channels CHA and CHB of the workbench 3 Now configure the ELVIS Function Generator to the following settings 1 Connect the Function Generator FUNC_OUT pin to the location
6. arkers Markers allow users to specify where voltage and current waveforms are to be analyzed and simulated on the circuit from the schematic Markers may be accessed by selecting Markers from the drop down menu Below is a description of several of the available options Mark Voltage Level Measures voltage level with respect to ground Mark Voltage Differential Measures the differential voltage between two user defined points Mark Current into Pin Measures the current entering a node Mark Advanced Provides several advanced measuring options including decibel readings of voltage and current Setting up a Simulation PSpice requires that all schematics be saved before any simulations may be conducted Once a schematic has been saved the user should access Analysis gt Setup from the drop down menu This should bring up the following dialog box Analysis Setup Enabled Enabled AC Sweep Options Close Load Bias Foint Parametric Save Bias Point Sensitivity Monte Caro worst Caze Transter Function Bias Point Detail Transient Digital Setup Figure 5 4 Setup dialog box DC Sweep Temperature Figure 5 4 presents the numerous available simulation options In this case we will only be concerned with selecting Bias Point Detail as well as Transient options These options will allow the user to plot time varying signals Enable these options by placing a checkmark next to ea
7. browse through Again this option may be directly accessed from the toolbar To enable this option press the button to the immediate left of the Get Recent Part list box Pressing this button should enable the dialog box presented below Part Browser Advanced Part Name Description Search E oO Description Create Mew Part List Search Library al p YwinappehlSimaprosibrANALOG al Close Place R P Place amp Close Help Libraries Basic R296210 5 Edit Symbol Full List Figure5 3 Part Browser dialog box Figure 5 3 above presents one of the two dialog boxes that may appear These may be the Part Browser Advanced and Part Browser Basic dialog boxes Although both modes can be used to select parts Part Browser Advanced provides extended options for part placement These include descriptive searches as well as a symbolic representation of the selected part You can switCH Between modes by selecting the Basic or Advanced buttons In addition to the above method the part browser dialog box may also be accessed at Draw gt Get New Part or by using the lt Ctrl G gt shortcut Placing Wires PSpice defines several methods for wire placement Again this option may be accessed from the toolbar in Figure 5 2 To place wires simply select the leftmost available icon on the toolbar In addition to this method wires may be placed from both Draw gt Wire or by selecting the lt Ctrl W gt shortcut Placing M
8. ce to be 4Ix then simply double click on the part and enter 4 for the gain Exercises Simulate and determine the voltage V1 Figure 5 14 Simulate and determine v2 40 Q 30 V Figure 5 15 Tutorial B Oscilloscope Training Drill I Introduction to the NI ELVIS Oscilloscope 1 Start the ELVIS command console by going to the Windows Start menu and selecting Programs gt National Instruments gt NI ELVIS 2 0 gt NI ELVIS 2 Start the ELVIS oscilloscope by selecting Oscilloscope from the NI ELVIS command console The following interface should be displayed on the desktop gt NI ELVIS Oscilloscope E K T NATIONAL E TANE a CHANNEL BR INSTRUMENTS a Display Display Source Source IBNCiBoard CHA ow BNCiBoard CHE YERTICAL YERTICAL Position Position U Cao Caro Scale JZ z y v div Coupling Coupling De Autoscale Do ye TRIGGER AUGE Eavan _Immediate CURSORS Timeout ei CHA ce CHA Acquired Figure 5 16 ELVIS Oscilloscope e Channel A Controls o Display tTurns the display of input signal measurements for channel A ON or OFF The default value for this button is ON Note Acquisition on CH A continues even if the trace is not displayed o MEAS Turns the display of measurements for channel A on or off The MEAS button is green when active Measurements are displayed below the graph in the Measurements and Cursors Display portion of the Display W
9. ch In addition to selecting Transient from the dialog box click on the Transient button You should see the following dialog box appear Transient Transient Analysis Print Step i n Final Time i 0n No Frint Delay Step Ceiling Detailed Bias Pt T Skip initial transient solution Fourier nalysis Enable Fourier Center Frequency Number of harmonics Output Wars OF Cancel Figure 5 5 Transient dialog box The Transient dialog box allows users to set final simulation times as well integer step values for simulation Smaller step values allow for increased resolution in resulting plots however this comes at the expense of increased simulation time Care must be taken at both extremes Large step values can results in coarse output plots or even worse the resulting signal may become aliased To prevent aliasing make sure your print step is smaller than half the period of the highest frequency signal in your circuit Once a step size and a final time have been selected you are now able to proceed with the simulation Exit the Transient dialog box by clicking on the OK button Then proceed to exit the Analysis Setup by clicking on the Close button To initiate a simulation go to Analysis gt Simulate Doing so should begin the simulation as long as there are no errors in your circuit At this point you should see a dialog box that resembles Figure 5 6 on your screen 4 Schematic1 cir PSpiceA
10. d in PSpice Table 1 1 shows the different types of dependent sources as well as the part name that PSpice uses to identify them and Figure 5 10 illustrates each sources symbol H F Current controlled voltage source CCVS ow Current controlled current source CCCS T Table 1 1 E1 H1 Figure 5 10 As is shown in Figure 5 10 each dependent source has two sides associated with the part The side without the circle measures the dependence and the side with the circle is the actual source either voltage or current A clearer explanation can be seen with an example Example Simulate the circuit in Figure 5 11 Figure 5 11 To simulate this circuit the dependent source must be inserted into the circuit properly as shown in Figure 5 12 Figure 5 12 For a voltage controlled VCVS or VCCS dependent source the measuring side of the part must be placed in parallel with the dependent element and the polarities must be correct for proper simulation To make the controlling source the necessary 4 times Vx you must double click on the part and enter 4 in for the gain parameter If we were concerned with a current controlled voltage source that was controlled with the current Ix then we would need to use the part H and then the measuring side of the part would be connected in series with the dependent element as seen in Figure 5 13 Figure 5 13 Again if we were wanted the value of the current controlled sour
11. dding a DC offset to your waveform is NOT the same as moving the reference point on the display This should be apparent for the options displayed below the plots IV Exercise 1 This part of the experiment will allow the student to practice making AC measurements using the VB scope a Set up the following circuit Figure 5 18 b Set the input signal to a sine wave at 2 kHz 0 V DC offset and 8 Vp p Additionally restore the settings on the VB Scope to those described in step 1 of exercise 1 C Configure channels A and B of the VB scope to look at V1 and V2 respectively Be sure to set input coupling to DC auto triggering and a trigger noise rejection ratio of ImV You should see two sinusoids of the same frequency with a phase difference displayed on your screen d Use the cursors to determine the delay dT between both sinusoids What is the phase difference between the two sinusoids Note dT frequency 360
12. from the signal or DC allow NI ELVIS to measure all of the signal The default for value for this control is DC Autoscale Adyjusts the voltage display scale of the graph based on the peak to peak voltage of the AC signal greater than 5 Hz for an automatic best fit display of the signal e Channel B Controls O Display Turns the display of the CH B trace on or off The default value for this button is ON Note Acquisition on CH B continues even if the trace is not displayed MEAS Turns the display of measurements for channel B on or off The MEAS button is green when active Measurements are displayed below the graph in the Measurements and Control Display portion of the Display Window The standard measurements are RMS frequency and Vp p The MEAS button for CH B is dimmed if the Display button for CH B is OFF Turning this feature on when the CH A MEAS button is on sets the CH A MEAS button to off The default value for this button is OFF Source Selects the signal source for the measurement on CH B You can select ACH lt 0 2 gt ACH5 the BNC Board CH B the function generator FUNC_OUT signal the function generator SYNC_OUT signal and the DMM VOLTAGE channel routed to ACH7 The default value for this control is BNC Board CH B Vertical Position Knob Adjusts the vertical position of the channel B trace by applying a positive or negative vertical offset The offset is referenced from the zero point of the graph Thi
13. hould now be able to drag cursors on the waveform observed on channel A of the display Note that you must enable channel B before selecting the cursor for channel B Below the plot you should observe information on the positions of the two cursors This information should include both voltage levels as well as differential times between the two cursors De select the Cursor option on the scope Now return to the FG display and switch through the various different waveforms available on the display You should be able to select between sine square and triangular Additional waveforms may also be user defined Set the output waveform of the FG to a square and then triangular wave On the front panel of the FG try turning the knob labeled Offset Observe and answer the following questions Can you observe any differences in the displayed signal If so what do you observe Do these settings have any effect on the parameters displayed below the plot Explain Set the displayed waveform to the same settings described in step 4 but now configure the channel settings to AC coupling Do you observe any changes in the displayed waveform Now increase or decrease the DC offset of the signal Is there any difference in the displayed waveform Should there be Explain Set the oscilloscope to two different waveforms provided for by the instructor These waveforms should be at different offsets amplitudes frequencies as well as duty cycles Note A
14. indow The standard measurements are root mean square RMS frequency and V _ The MEAS button for CH A is dimmed if the Display button for CH A is OFF Clicking this button when the MEAS button for Channel B is on sets the CH B MEAS button to OFF The default value for this button is OFF Source Selects the signal source for the measurement on CH A You can select ACH lt 0 2 gt ACHS5 the BNC Board CH A the function generator FUNC_OUT signal the function generator SYNC_OUT signal and the DMM VOLTAGE channel routed to ACH7 The default value for this control is BNC Board CH A Vertical Position Knob Adjusts the vertical position of the CH A trace by applying a positive or negative vertical offset The default is zero offset The offset is referenced from the zero point of the graph This offset value is not applied to the actual acquired data Zero Centers CH A on the vertical zero point of the graph This action does not affect the actual acquired data The default is no action Scale Div Selects the vertical sensitivity for the channel A trace Sensitivity is defined as the amount of voltage represented by each horizontal line on the graph The units are in volts division The Scale Div options are 10mV 20mV 50mV 100mV 200mV 500mV 1V 2V and 5V The default value for this control is 2V Coupling Specifies the coupling for the channel This operation is done in the software You can select AC removes the DC offset
15. rator NATIONAL INSTRUMENTS i 3 MAMOA AL na 2 Frequency Waveforms 20 Hz Peak Amplitude DC Offset 500 Hz ce 5 kHz me aa 50 kHz o m 250 kHz 100 00 Frequency Sweep Start Frequ step Hz 100 0 Hz 100 00 Tuning Mode UltraFine ae Stare Stop Sal Far Stop Frequency ay Analog AEE Modulation 1000 0 2 He HELP Figure 5 17 ELVIS Function Generator The NI ELVIS FGEN SFP is a top level stand alone instrument that controls the function generator in the NI ELVIS Benchtop Workstation It allows setting of the following features e Waveform sine triangle square e Tuning mode basic low resolution fast 8 bit fine frequency ultrafine slower 12 bit fine frequency e Modulation disabled software AM or FM using DACO or DAC1 e Frequency adjust e Amplitude 8 bit e DC offset 8 bit e Measure frequency of generated signal You can control the function generator either through the NI ELVIS FGEN SFP Software mode or the hardware controls on the benchtop workstation Manual mode This section describes the software controls Refer to the NJ ELVIS Benchtop Workstation section of Chapter 3 Hardware Overview of the NI ELVIS User Manual for more information on the hardware controls for the function generator The tab labeled Large Amplitude Waveform is capable of providing signals with amplitudes larger than 2 5 Vpeak The output from this panel is available on DACO NOT FUNC_O
16. s offset value is not applied the actual acquired data The default is zero offset Zero Centers the CH B trace on the vertical zero point of the graph The default is no action This action does not affect the actual acquired data Scale Div Selects the vertical sensitivity for the channel B trace The units are in volts division Sensitivity is defined as the amount of voltage represented by each horizontal line on the graph The Scale Div options are 10 mV 20 mV 50 mV 100 mV 200 mV 500 mV 1 V 2 V and 5 V The default value for this control is 2 V o Coupling Specifies the coupling for the channel This operation is done in the software You can select AC removes the DC offset from the signal or DC allow NI ELVIS to measure all of the signal The default for value for this control is DC o Autoscale Adjusts the voltage display scale of the graph based on the peak to peak voltage of the AC signal greater than 5 Hz for an automatic best fit display of the signal Display Window Displays the waveforms specified in channel A CH A Source and channel B CH B Source as well as cursors Cursors are moved horizontally by clicking them and dragging them along the time axis The signals are plotted amplitude versus time The Display Window includes the following controls and indicators Measurements and Cursors Display The Measurements and Cursors Display includes the following indicators RMS Displays the measured
17. where the signal is needed ll Launch the NI ELVIS FGEN SFP from the NI ELVIS Instrument Launcher ill Choose the desired value from the Waveform Peak Amplitude DC Offset Fine Frequency and Coarse Frequency controls IV Click the On button on the NI ELVIS FGEN SFP to begin generation 4 Set the function generator to Frequency 500 Hz Duty Cycle 50 Offset 0 Amplitude 5 Vpk Input Signal Sine wave 10 11 Set both the function generator as well as the oscilloscope for continuos signal generation and acquisition by pressing the Run or On buttons on either device You should now see a sine wave at a frequency of 500 Hz O V offset and 5Vpk If you do not try pressing Autoscale on the front panel of the scope Additionally notice the parameters that appear below the display You should find helpful information on frequency period voltage levels offset etc More options may be configured in the General Settings tab On the front panel of the VB Scope try turning the knobs labeled Time Base Volts div and V Position Answer the following questions Can you observe any differences in the displayed signal If so what do you observe Do these settings have any effect on the parameters displayed below the plot Now press the button labeled Slope What effect does this have on the display Select the option labeled Cursor on the front panel of the VB Scope display and set to the following CH A CH B You s
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