Discussion in 'Electronic Basics' started by Irfan, Jun 20, 2006.

1. ### IrfanGuest

How can i simulate the circuit below as it has no source. How can i
insert the value of 9mA,8mA and 12mA current flowing through the wires.

http://i5.tinypic.com/153l8jb.jpg

2. ### Alan BGuest

Do you mean "simulate," or do you mean "solve?"

3. ### Dorian McIntireGuest

The arrows are the current sources.

You've got to learn Kirchhoff's current law and forget the simulation stuff
until later. Kirchhoff's current law states that the sum of currents
entering a node is zero.

Assume all currents flowing into a node are positive and currents leaving a
node are negative (any assumption will work as long as you're consistent):

8mA - i1 - 12mA = 0: 8mA - 12mA = i1 = -4mA

12mA + i3 - 9mA = 0: -12mA + 9mA = i3 = -3mA

9mA - i2 - 8mA = 0: 9mA - 8mA = i2 = 1mA

Check: I2 + I1 - I3 = 0: 1mA + (-4mA) - (-3mA) = 1mA -4mA + 3mA = 0

Dorian

4. ### IrfanGuest

Yes i know the current law. What i mean here is to make this circuit on
computer and simulate it using orcad capture cis software or what will
be the coding of pspice for this circuit.

6. ### Guest

I think what you are trying to do is insert dependent current sources
for 9-, 8- and 12-mA. Press 'P' for parts (or click on parts), choose
Source under libraries, then select IDC (DC current source). Click OK
and place the current sources according to your diagram. Wire the
circuit, and don't forget to include a ground. I would also include
some 0 Ohm resistors in the other branches just to make it easier to
simulate. Save the circuit. Under simulation profile, choose Transient
and the default period (it shouldn't matter). Press OK and then press
the blue arrow to simulate the circuit. Click on Add Trace and choose
I(R1), I(R2), I(R3).