# Performing mesh analysis with current sources...

Discussion in 'Electronic Basics' started by David, Sep 21, 2007.

1. ### DavidGuest

Someone told me I need a positive voltage source to perform mesh analysis on
this circuit:

http://img260.imageshack.us/img260/4665/deletemecircuituz9.jpg

Is this true?

I don't see how the voltages in the outer loop can add to 0.

I've solved this with nodal analysis but have not been able to with mesh
analysis yet. The equations I've come up with are:

(both currents assumed clockwise)

i2 - i1 = Va/4
i2 = -1

I was thinking a Supermesh would provide the third equation I need but all I
see from that is:

i1*2 + i2*3 = 0 but from the PSpice analysis I know this isn't going to lead
to a solution.

Thanks

2. ### DavidGuest

I should have mentioned that the gain of the voltage controlled current
source is .25.

I was able to solve the problem by using the VCCS to determine the potential
across the constant current source. I'm not sure what rule I am using
though.

When creating a supermesh around the entire circuit it seems to me like the
constant current source should be the loop current. I don't see why I
should have thought to calculate the voltage across the current source in
the first place...

Here are the final equations I've used:

i1 - i2 = Vab/4 -constraint from VCCS
i2 = -1 -known loop current
2(i1) - 3 = (i1 + 1)4 -supermesh