Transform independent into dependent source

Thread Starter

Claudinho18

Joined Jan 14, 2017
6
Hi all. I have this circuit. I want to transform one of these sources into a dependent source. Can you tell me how? What's the new figure and the relations? Thank you.
upload_2017-9-2_22-31-13.png
 

WBahn

Joined Mar 31, 2012
29,979
It's unclear what it is that you are trying to achieve.

The term "transform" (in a context such as this) generally means to change it into something that behaves the same way such that the rest of the circuit can't tell the difference. If you replace an independent source with a dependent source, then as you change other parts of the circuit the entire circuit will behave differently than it would if you hadn't changed it.

If all you are trying to do is replace one of the sources with a dependent source such that the snapshot of the circuit remains unchanged (i.e., when all of the other components are exactly as they were originally), then all you need to do is pick one of the sources. Decide what kind of dependent source you want to replace it with (you have four options), pick a control variable from among all of the other choices of voltage or current (depending on what type of source you chose), and then determine the appropriate scaling value.

To see if you understand this, you have five independent sources.

Label them S1 through S5.

Now write down the following terms of five index cards or scraps of paper: Independent, VCVS, CCVS, VCCS, CCCC and shuffle them. Then, in order, write S1 through S5 on them. The one that has Independent written on it remains unchanged. For the others, replace the source in the original circuit with the type of source written on the corresponding card. For you control variables, you could randomly pick a voltage (or current, as needed) related to one of the resistors, or any branch current, or the voltage difference between any two nodes.
 

Thread Starter

Claudinho18

Joined Jan 14, 2017
6
I have to "modify the circuit, tranforming one independent voltage/current source into one linear controlled source(one of these 4 possible choices). As command,choice the current or voltage from another branch, not that with the dependent source. Determine the parameter of dependent source for obtain the same behavior. ." . At next point I have to resolve the circuit with Kirchkoff method.

I am thinking to note one voltage/current value from the circuit with a variable and write on that dependent source A*that variable, where A is parameter of the dependent source, but that seems too easy.
 

WBahn

Joined Mar 31, 2012
29,979
I have to "modify the circuit, tranforming one independent voltage/current source into one linear controlled source(one of these 4 possible choices). As command,choice the current or voltage from another branch, not that with the dependent source. Determine the parameter of dependent source for obtain the same behavior. ." . At next point I have to resolve the circuit with Kirchkoff method.

I am thinking to note one voltage/current value from the circuit with a variable and write on that dependent source A*that variable, where A is parameter of the dependent source, but that seems too easy.
It doesn't sounds like it's much more difficult than that.

To test out your ability to do so, you might make a simpler circuit, say one with three vertical branches between a top and bottom node. Say a 12 V battery in parallel with a 6 Ω resistor and then in parallel with a 2 Ω resistor that is in series with a 4 A current source. Find all of the voltages and currents. Then replace the 12 V battery with a CCCS and use the current in the 6 Ω resistance as the control signal. Then analyze that circuit and see if you get the same voltages and currents as before. If you do, then you should be able to tackle the assigned problem with confidence, or even do the more general one that I suggested. If you turn that one in, you might get some extra credit. But even if you don't, you will have gained a lot more practice and learned more, which is what it should really be about, right?
 
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