EE124 Web Site - Introduction to PSPICE


Starting up PSPICE and Building the example Circuit
A. PSPICE Program Installation.
        Follow the instructions provided with the PSPICE program and install it on your computer.

B. Program Schematics Startup.
        1. For Window 95/98/NT users, go to the Start Menu and left click the mouse.
        2. Under the Start Menu, find Programs and left click the mouse again.
        3. Find the folder named either DesignLab Eval 8 or Microsim Eval 8 and again left click.
        4. Finally, left click on Schematics. The Schematics section of the PSPICE program should start up.

C. Building the Example Circuit.

a. Operational Amplifier.
1.  Go to the Menu Bar under the Schematics title bar and click on Draw.
2. Under the Draw option list, left click on Get New Part.

3. Left CLick on Advanced >> to expand the Part window. Go to the window labeled Full List and down scroll until you see uA741.

4. Click on uA741. Left click on Place & Close. The Library menu should disappear and you are left with an outline of an Operational Amplifier symbol (Tip: If necessary, to rotate the symbol press Ctrl-R, to flip the symbol press Ctrl-F). Move the symbol to somewhere in the middle of the schematic display and Left Click to permanently place it.


 

b. Power sources for the Operational Amplifier.
1. Repeat steps C.a.1. and C.a.2.
2. Scroll down the Full List window until you see VDC. Select this and then Left click Place & Close. Place this symbol somwhere to the upper right of the Op Amp symbol without crossing the two symbols by Left Clicking it.

3. Double Left Click the VDC symbol. A Symbol Characteristic Menu should pop up.

    Left click on VDC=0V in the large window. In the two small windows above it, the name VDC and 0V should appear.  Change the 0V value displayed to 10V. Left Click on Save Attr to confirm the change of this value.
4. Now, click on PKGREF=V1 (or some other name other than V1) and enter VCC in the place of V1 as detailed in the step above. Left Click on Save Attr and then Ok to close the Characteristics window. The Schematics should show a 10 V DC source named VCC.

Another way of doing the renaming and revaluing Components is to Double Left Click directly on whatever name or value is being displayed.
5. Get another VDC component by almost exactly repeating steps C.b.1. to C.b.2. and place it below VCC without crossing symbols. Using stepes C.b.3 and C.b.4 rename this symbol VEE and give it a value of 10V.

c. Placing Resistance and Capacitor.
1. Using the methods detailed in C.a. and C.b. get a resistance (component R) and place it to the left of the - (minus) terminal of the OP Amp(Remember no touching components). Give it a value of 10k (10 kilo-Ohms).
2. Get a capacitor (component C) and place it a little far below the Op Amp. Give it a value of 10n (10 nano-Farad). Note that P-Spice has special notations for different magnitudes:
 
 

Scale
Unit
P-SPICE unit
106
Mega
meg
103
kilo
k
10-3
mili
m
10-6
micro
u
10-9
nano
n
10-12
pico
p
10-15
femto
f

 

3. Get another resistor R2, give it a value of 10k and place it under C1











d. Placing the ground terminal.
    The ground to be used is a component named GND_ANALOG. Get two of them. Place one on the right side of the middle of the two VDC sources. Place the other one just under the + (plus) terminal but above the resistor.

e. Drawing Wires.
    Go to the toolbar and Left Click on Draw. Left Click on Wire. The cursor should now change shape to a crosshair. Left Click to fix the starting location of the wire.

    Move the cursor around to the destination terminal location and Left Click again.  This should fix the wire on the schematic. Note that the wire does not end as long as it has not connected to a component. This characterestic allows the user to make more complex wire patterns without crossing wires unintentionally (See the connection between u741-6 and C1). Also note that a large blue dot over crossing wires indicate that they are electrically connected (see the VCC- to VEE+ to GND connection). No blue dot means no connection.
    Repeat this as many times as necessary to complete the circuit, connecting all the components together. These are the connections that you should have made. u741-7 to VCC+, VCC- to VEE+ and also to GND, u741-4 to VEE-, u741-3 to GND, u741-2 to R1 (right-side) and C1 (left-side), and finally C1(right-side) to u741-6.
    If you make a mistake on one of the wires, simply Left Click on it and press Delete.

f. Saving Schematic File.
    Go to the toolbar and Left Click on File. Left Click on Save. Type a name in (for example, LPfilter) and save your file.
 

    The circuit is finally fully built and done. For further study refer to the other sections.

D. Things to Remember.

1. Use Start-Menu-Programs-Microsim Eval8 (or DesignLab Eval 8) - Schematics to start up the P-SPICE program.
2. To draw a part use Draw-Get New Part. Use the Advanced >> button in the corresponding part menu to see the part's symbol. After selecting the part use Place & Close to put part on schematic.
3. Parts may be rotated (Ctrl-R) or flipped (Ctrl-F) before being fixed on the schematic.
4. Characteristics of a part (for example its name and value) may be changed by double Left clicking on the part to call up its Attribute Menu. A part's parameter may also be changed by directly clicking on a displayed paramenter.
5. Wires may be drawn by using Draw-Wire. Remember that the large blue dot means that the crossing wires ARE electrically connected.
6. Do not forget to Save the file often.


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