PSpice Version 9.1 Schematics

Objective of LectureDemonstrate how to use PSpice Schematics

to calculate node voltages and the currents flowing into and out of nodes.Most circuit simulation packages use nodal

analysis.

Download InstructionsInstructions on how to download and install

PSpice are posted on the Virginia Tech ECE Computer and Visualization Laboratory (CVL) website.http://computing.ece.vt.edu/wiki/PSpice_FAQ

After Launching PSpice Schematics

Select Draw/Get New Part, which will cause a pop-up window to open with a list of all of the parts available in the student version of Schematics. - Note that there is a key stroke shortcut .

Pick a PartType the name of the part in the box located by Part Name orscroll through the list of parts andclick on the name of the one thatyou want put into the circuit.

Then, click Place if you have moreparts to select or Place and Close if this is the last part.

If You Know the Name of Your PartYou can type it in directly into the box below the

Toolbar Help and then hit Enter.

Either way, a symbol for a dc battery will appear on the schematic when you move your cursor on to it. Left Click to place the part in a specific location on the

schematic. Right Click to end the process of placing the part Vdc. Control-R will rotate the part 90 degrees for each CNT-R. Control-F will flip the part about a vertical axis.

Names of ComponentsComponent PSpice

NameComponent PSpice

Name

DC voltage supply

Vdc Resistor R

DC current supply

Idc Capacitor C

Ground gnd_earth Inductor L

Connect Parts

Click on the pencil.

Then click the pencil tip to one end of a part and then to the end of another part to place a wire between them..

Save Your SchematicPSpice will not run a simulation unless your

circuit is saved.You can select any directory in which to save

the .sch file. Note: You can send the .sch file to me if you need

assistance finding errors that prevent the simulation from running.

Select Type of SimulationClick on Analysis/Setup or the button.

Bias Point Detail should be clicked. If not, do so.

GroundA ground must be included in the circuit as

the program calculates all voltages with respect to this point.Note: The first step that I identified in the

lecture on nodal analysis was to select one node as the reference or ground, which means that the voltage at the node will be set to 0V.

A common error message in PSpice is that the ground is not connected. After verifying that you did place a ground in the

circuit schematic, make sure that a node (dot) connects ground to the circuit.

Run the SimulationClick Analysis/Simulate or click on the

button.

A pop-up window should open, text should scroll by in the bottom left box. After “Simulation complete” is printed, the run is finished.

To Display DC ValuesClick on Analysis/Display Results on

Schematic and enable the voltage and/or current display.

Node AssignmentClick on the box containing the value of the

node voltage.The node associated with that voltage is

changed to a dashed line.

Direction of Current Click on the box containing the value of

current flowing at a node. An arrow will appear on the schematic,

indicating the direction that the program assigned to the flow of that current.

Voltage Across ComponentsNote that the calculation performed by

PSpice is a nodal analysis. The voltage dropped across a component is the difference between node voltages.

SummaryPSpice may be used to verify the calculations

that you perform to calculate the currents and voltages in a circuit, but should not replace your own calculations.The results from PSpice should be the same as

the results that you obtain for the circuit when using nodal analysis.

The voltages and currents from nodal analysis can be converted to the voltage drops and mesh currents used in mesh analysis.