electrical free software

ORCAD ORCAD

Enter capture and create a new project

From start button go to programorcad capture .
In the opened window go to filenew and select "project". A Window will open .Enter project's name in the "name" section , select Analog or Mixed A/D in the "create new…" section and select a path , where you want to save your project in the "browse" section and click ok . After doing that a window will open. In this window select "create a blank project".
A window like below will open which you can draw your circuit and simulate it.

The way to bring parts and wiring

To bring a part go to placepart or click

."Add Library", "add new library".
You can remove the library with "Remove Library".
To search a part select "Part search". ( by typing part name in the "part" section you can access directly to the part.)

You can access a part by typing its name in the "Place Part" in the schematic page.

To wire circuit click

or press "W", as you press wire , the cursor will change to "+".

Change part's value:

To change part's value ,double click it and in the "value" type the part's value.
If you type the value without any symbol , the part's value will be in ohm
Symbols:
K: kilo ohms
Meg: mega ohms

Rename a part:
To rename a part, double click the part's name

Node DC analysis :

Suppose you want to find voltage, current and power of the circuit below

First we have to define a ground for the circuit, to open the window below click

To simulate you should select

After completing the circuit, we should simulate it. To do this click

In the "Name" section , type a name and in "Inherit form", select none and then click

In the "Analysis type" section, select "Bias point" To see voltages, currents and power just click

, before clicking, select

Dependent sources:

Dependent sources are divided into several types in orcad

a) EPOLY: voltage source depends voltage
b) HPOLY: voltage source depends current
c) GPOLY: current source depends voltage
d) FPOLY : current source depends current
In this example we will analyze EPOLY
Draw a circuit like the circuit below and the test dependent source relates to R2

Now we have to determine the quantity of relation between EPOLY and voltage of R2
To do this we double click on its schematic to open the window below

In the "COEFF" cadre we determine the quantity of relation, in this example we insert 5 to show the variation vividly. After determining, close the window and in the schematic page click

.to simulate select "Bias Point".
After adjusting simulation we return to the main page and click

then to show the voltage, click

As you know the voltage on each resistor is 10V but at the EPOLY output, it is 50V.
The second circuit that we want to analyze, is a HPOLY .

The voltage on R3 depends on the current that passes through R1 and R2.
Their current is 1.5MA.
To adjust HPOLY, double click its schematic and in the "COEFF" cadre

type the desired value (in this example it is 4), return to the schematic page and click

, select "Bias Point" and click OK. Then select

and to show voltage click mohem As you can see the dropped voltage across R3 is 6MV and it is four times greater than the current of R1,R2.
The result of simulation:

Transient analysis

The pulse source in orcad is like the picture below

To bring it , you can type "VPULSE" in the "Part Place"
a) V1: It determines the minimum voltage of the pulse
b) V2: It determines the maximum voltage of the pulse
c) TD: the time that takes the pulse starts moving upward
d) TR: the whole time takes V1 reaches V2
e) TF: the whole time takes V2 reaches V1
f) PW: it determines the pulse width
g) PER: it determines when complete figure occurs
Sample:

To see the output signal you should name the output. Click

and in the opened window in "Alias" enter the name

After you completed circuit you must simulate it.
Click

and select name for simulation and click OK after that this window will open

In "Analysis type" , select "Time Domain" and you can determine the time which you want to see the pulse until that , in the "Run to time" section ( in this example 30ms)
Then click OK and in the schematic page after initializing the pulse source click

hence the window like the picture below will open

To see the output voltage click "Add Trace"

In the "Simulation output" select "V [VOUT]" and click OK

Rectifier circuits:

First select a transformer like the picture below

Then draw a rectifier circuit like this circuit

To see the input and the output signal we can use

(by placing it on the wire)
V1 is a sinusoidal source (VSin)
VOFF: Adjust voff to zero
VAMPL: determines the amplitude
FREQ: determines the frequency
To adjust the transformer double click it in order to open the related window, then in the

cadre, enter the value of the transformer in (H)
In the main page click

and then to simulate select

At the "Run to time" section enter the proper value

After finishing click

The full wave rectifier

Clampers

DC SWEEP:

The input-output characteristic of the diode
Draw the circuit below

Go to "New Simulation" and select "DC SWEEP"
This window will open

In the "voltage source" write the voltage source name
In the "start value" write the initial voltage and in "end value" write the final voltage
"Increment" is determines the value of paces
Click OK then Click

.
In the window press "probe"