Superposition, Moving Around CKT Elements

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Discussion Overview

The discussion revolves around the application of superposition in circuit analysis, specifically regarding the treatment of dependent sources in relation to independent sources and resistors. Participants explore the implications of shorting and opening circuit elements to analyze voltage across a resistor.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant suggests using voltage division to find the voltage across a 20 ohm resistor after shorting a dependent current source and relocating an independent source.
  • Another participant argues that conventional wisdom dictates that dependent sources cannot be deactivated during superposition, questioning the validity of the proposed approach.
  • A different participant clarifies that shorting the dependent current source would also short the 20 ohm resistor, leading to a zero output from the voltage divider.
  • Another contribution emphasizes the importance of retaining the dependent current source in its original position and suggests calculating the contributions to the output voltage (Vo) separately from the independent sources.
  • One participant proposes solving the circuit equations twice, once with the independent current source removed and once with the independent voltage source set to zero, while keeping the dependent current source intact.

Areas of Agreement / Disagreement

Participants express differing views on the treatment of dependent sources in the context of superposition, with no consensus reached on the validity of shorting the dependent source or the implications for the circuit analysis.

Contextual Notes

Participants highlight the need to consider the effects of shorting and opening circuit elements, as well as the role of dependent sources, which may depend on specific definitions and assumptions in circuit analysis.

eatsleep
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2. V=IR, Voltage division, KCL, KVL
3. When I short out the dependent current source by replacing it with an open, can I switch the location of the independent source and the 20 ohm resistor so I can do a voltage division to find the voltage across the 20ohm resistor which is then equal to Vo because they are in parallel?
 
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The conventional wisdom is that you can't deactivate dependent sources when doing superposition. See this for more info:

http://users.ece.gatech.edu/mleach/papers/superpos.pdf

But, if you did short the dependent current source in your circuit, the 20 ohm resistor would also be shorted, wouldn't it? So your voltage divider wouldn't have any output since one leg of it would be zero ohms.
 
eatsleep said:
When I short out the dependent current source by replacing it with an open,
"short" ≠ "open"[/size]

I'd retain the dependent current source where it is. Find the contribution of the voltage source to Vo. Then find the contribution of the current source to Vo.
 
Solve the equations twice, once with the 3A source removed and once again with the 15V source set to zero volts (a wire in other words).

In each case the dependent current source 2Ix must remain in place.
 

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