# Analyzing a circuit with a diode using Matrices and the Gauss Algorithm

Discussion in 'Homework Help' started by Grojcig, Aug 1, 2011.

1. ### Grojcig Thread Starter New Member

Aug 1, 2011
1
0
Hi everyone!

I've just started studying EE on the University of Applied Sciences in Vienna this year. In the second semester we started learning about Matrices and how to solve equation systems with arbitrary amounts of variables using the Gauss(-Jordan) Algorithm. My question would be about analyzing circuits using Matrices. I've got the following circuit:

Exercise 3.8: Analyzing a circuit with a diode inside using Matrices and the Gauss Algorithm.

So far I've managed to analyze the circuit using Kirchoffs mesh and node laws:

Then I've established the solution matrix:

Unfortunately I must have messed up somewhere (like always) and when I try to solve the equation with the 4 variables. I get that 0 = 4.6 which tells me that the equation system cannot be solved.

How would you guys solve this problem? Can anyone help me with this?

I really want to learn how this works and add another useful tool into my arsenal when it comes to analyzing circuits.

2. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
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Looking at the source polarity (lower side more positive) in your schematic it would seem the diode would be reverse biased & therefore would not conduct. So it would be excluded from the analysis.

3. ### steveb Senior Member

Jul 3, 2008
2,433
469
Actually, the notation used to specify the voltage source is confusing. Isn't it?

A voltage source should use a + and - sign and not an arrow because the arrow makes it look like a current source. But, a voltage source with a current arrow in that direction would have the lower side more positive, as you say.

I'd be willing to bet the polarity is actually reversed and that it is just notated improperly (or by a different convention).

Last edited: Aug 2, 2011