Transcript BasicStart

Basic Pspice Instructions
Stuart Tewksbury
These notes provide a quick tour through the drawing of a schematic using Orcad’s
Pspice version 9. They are intended to assist the student in learning to use Pspice
for E245 and E246. After completing this simple tutorial, the student is
encouraged to draw upon Pspice in the verification that solutions to homework
(analytic problems) are correct. Pspice verifications can be included along with
the homework problems in E245 if the student so desires.
NOTE: Students have had difficulties replicating the following tutorial due to
incorrect setting the initial mode. When you enter the Orcad directory, you will
find a number of files. Start as follows.
• Rather than opening the “PSpice Demo” executable, open “Capture CIS
Demo.”
• When starting a new project, make sure the “Analog or Mixed-Signal Circuit
Wizard” mode is selected.
A
“File” -> “New” -> “Project”.
Then specify project name and directory in which to store the project. Screen below appears
and you can draw your circuit on this.
B
Click to choose
components.
New screen
appears allowing
you to select a
component.
C
We will first add a
voltage source. First
choose “library” =
“SOURCE.” Then
Choose “Part” =“
VDC.” This selects a
constant voltage
source. The picture of
the component
appears, When ready,
click “OK.”
Click in schematic capture window and selected component
appears on screen below. Click again and another of the same
component appears.
Second click gives
this one. Right
click to stop
adding voltage
sources. You can
delete one by
clicking on it and
pressing “delete”
Click
for
next
item
First appearing
when you click
The next page shows addition of resistors
Rotate by rightclicking while
adding components
Next, add wires to
connect elements
To make wires, first
click on one side of
an element, move
mouse to side of
other element you
want to connect to
and click again.
Wire now connects
VDC to R1.
Repeat process to
connect other
elements.
Circuit is now wired.
Next MUST add ground
connection.
Click here to select
ground
Next, we add a ground (REQUIRED)
Here, ground has
been added and
wired to circuit.
Circuit is now
complete. Save it.
There are errors
in the circuit
which will
interfere with
simulation.
(a) voltage source
is set to 0V and
will need to be
changed.
(b) wire
connection to
ground not
complete
Next: under Pspice menu, you will set up the simulation
These are the default settings.
You will adjust them,
depending on the time
constants of your circuit.
Here, we are simulating a DC
circuit so the time definition is
not important. But, we’ll
change it anyways.
Here, we have changed the time parameter, which will
determine the default times for the transient plots.
The error here
is because our
ground was not
properly
connected.
Here, we have
corrected the
faulty
connection to
the ground.
Ignore the extra
ground symbol.
My error but it
doesn’t matter.
Next, rerun the
simulation
(“run” under
the Pspice pulldown menu).
The simulation ran
successfully (see
bottom left).
However, nothing
appears. That’s
because we must
add traces.
You select traces by
clicking on the
“Trace” pull-down
menu and the “add
new trace” item.
This menu appears
when you add a trace,
allowing you to select
what you want to see.
We’ll select the
voltage across the
resstor labeled R2 in
the circuit diagram.
Whoops! The
voltage shown is
zero. Simulation
ran correctly but
what’s wrong.
Checking back on
the circuit, we
would see that the
voltage source had
not been set to a
voltage yet.
So, we’ll go back
and set the voltage
of the voltage
source, by double
clicking on the
voltage value
displayed.
Double clicking on the value given
for the voltage source brings up
this menu. Here, you can set the
value. If you enter a value and
also check “Name Only”, that
value is not used. So, you must
also check either “Value only” or
“Name and value”. When done,
click OK.
Here, we have changed the voltage
from 0V to 5V. Generally, you will
need to specify the units. You can
also use abbreviations for powers of
10.
Mega = millions
kilo = k = thousands
m = ,milli
u = micro
n = nano
p = pico
etc
After correcting voltage, run simulation again.
And, finally,
here’s the
correct result.
You could also
have clicked on
DC analysis and
obtained simply
a text value of
the voltage. You
should play
around with the
other setting
under the “Set
up Simulation”
window.