# Linear Circuit Help needed

#### Albinoswordfish

Joined Sep 4, 2007
5
Hi I'm stuck on this one problem I have for my linear circuit analysis class.
Right now I'm very confused on the affect a dependent source has on a circuit

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#### hgmjr

Joined Jan 28, 2005
9,027
Where do you get hung up in solving the problem?

Can you show us what you have tried in the way of solving the problem?

hgmjr

#### Albinoswordfish

Joined Sep 4, 2007
5
well I tried using current division to do the problem because the dependent current source and two resistors are in parallel. However the dependent source doesn't have a resistance across of it so current division doesn't work. I can't use voltage division because the resistors and dependent source are not in series.

Basically we just covered current division and voltage division in class, but can't see where to use it.

So now I'm stuck

#### hgmjr

Joined Jan 28, 2005
9,027
It is getting late so here so I will have to signoff. I am certain another member can provide you with some helpful hints to get you a little closer to the answer.

Good Luck,
hgmjr

#### techroomt

Joined May 19, 2004
198
i admit i have no idea what the diamond shaped device is on the right "g sub m". the given value is 0.2 mS, is that milli-Siemens? i assume one power source Is Vs ?!?

#### Distort10n

Joined Dec 25, 2006
429
i admit i have no idea what the diamond shaped device is on the right "g sub m". the given value is 0.2 mS, is that milli-Siemens? i assume one power source Is Vs ?!?
It is a dependent current source. Unfortunately, I never did much with dependent sources in class. I believe the dependent current source is controlled by the current through the indepedent source, so it is a CCCS. Current Controlled Current Source.

#### JoeJester

Joined Apr 26, 2005
4,390
It looks like a voltage controlled current source to me.

#### recca02

Joined Apr 2, 2007
1,212
the worst thing is superposition is supposed to not work (or atleast the way it is to be applied is different) in these cases. i have done similar examples before but now sadly have forgotten the approach for it(plus my ol' book went missing,it was the book i studied from). i m also not able to figure out the meaning of equivalent conductance as seen by current(does it mean the parallel branches of the dependent current source and the resistances?).

#### hgmjr

Joined Jan 28, 2005
9,027
well I tried using current division to do the problem because the dependent current source and two resistors are in parallel. However the dependent source doesn't have a resistance across of it so current division doesn't work. I can't use voltage division because the resistors and dependent source are not in series.

Basically we just covered current division and voltage division in class, but can't see where to use it.

So now I'm stuck
One way to tackle this problem is to apply Norton's Theorem. Review the material pointed to by the link or review any information in your textbook on Norton's Theorem.

The circuit contains two current sources in parallel with a resistance across them made up of R1 and R2 in series. The current sources are Is and gm*Vx. Use Norton's Theorem to write the equation for Vs based on the current sources and resistors and then see if you work out the answer from there.

If you get stuck tell us where you are stuck and we will try to help you advance beyond the sticking point.

hgmjr

#### JoeJester

Joined Apr 26, 2005
4,390
Albinoswordfish,