Two Frequency Input Solving for Output

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Discussion Overview

The discussion revolves around solving for the output voltage across a resistor in a circuit with a given input voltage that operates on two different frequencies. Participants explore the implications of using the superposition method and the need for circuit diagrams to clarify the problem.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Meta-discussion

Main Points Raised

  • One participant proposes using the superposition method to solve for the output voltage by treating the input as two separate voltage sources corresponding to the different frequencies.
  • Another participant argues that the output voltage across a load driven by a voltage source does not depend on the load impedance due to the source's zero output impedance.
  • A participant emphasizes the importance of clarifying that the output voltage refers to an arbitrary resistor in the circuit, suggesting that the voltage across individual resistors will differ from the total voltage source due to the presence of other components.
  • There is a suggestion that providing a circuit diagram would help avoid misunderstandings and clarify the discussion.
  • Some participants express confusion regarding the relevance of the superposition method and whether it is still taught, indicating a potential generational gap in understanding.
  • Humor is introduced in the discussion, with some participants making light-hearted comments about the tone of responses and the nature of the conversation.

Areas of Agreement / Disagreement

Participants generally agree on the use of the superposition method to analyze the circuit, but there is disagreement regarding the interpretation of the output voltage and the need for additional circuit details. The discussion remains unresolved on some technical aspects.

Contextual Notes

Participants note the lack of sufficient information about the circuit configuration, which may affect the analysis. There are also references to the need for clarity in communication to avoid misunderstandings.

Who May Find This Useful

This discussion may be useful for students and practitioners in electrical engineering or related fields who are exploring circuit analysis techniques, particularly in the context of frequency domain analysis and superposition.

KasraMohammad
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Say for example you have a Input Voltage in a circuit that is equal to Vin = 4cost + 5sin2t. Clearly, the input is operating on two different frequencies, namely w=1 and w=2. I am trying to find the Output Voltage across an arbitrary resistor in the circuit. The circuit consists of resistors and a capacitor, so its quite plain and standard.

My question is, how do you solve for the output given the above input, considering the different frequencies? My intuitions tells me to solve using Vin=4cost first and get the Vout, then solve using Vin=5sin2t and get another value for Vout, and the actual Vout will be the sum of the two. Is that correct?
 
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If you driving a load with a voltage source like what you gave, the voltage across the load is just Vin! Because you specified it is a voltage source and it has zero output impedance! It does not care what load it is!

I am just trying to give you a bad time. You have not given enough info on what is the output. You need to draw the circuit. Yes, if Vin = 4cost + 5sin2t, you treat is as two separate voltage one with w=1 and the other w=2.
 
I wasn't talking about the voltage across the TOTAL load. Read over the post again. I mentioned Vout being the Voltage across ONE arbitrary resistor in the circuit consisting of resistors(plural) and a capacitor. Thus, the voltage across the individual resistors will not equal the voltage source itself since there are other components also in the circuit. Give us newbs a hardtime, but don't forget reading comprehension! just giving you a hard time.

The last part of your post answered my question. So you treat it as two separate voltage sources. Thats what i needed. Thanks buddy!
 
Is Superposition method stiill taught?
 
KasraMohammad said:
I wasn't talking about the voltage across the TOTAL load. Read over the post again. I mentioned Vout being the Voltage across ONE arbitrary resistor in the circuit consisting of resistors(plural) and a capacitor. Thus, the voltage across the individual resistors will not equal the voltage source itself since there are other components also in the circuit. Give us newbs a hardtime, but don't forget reading comprehension! just giving you a hard time.

The last part of your post answered my question. So you treat it as two separate voltage sources. Thats what i needed. Thanks buddy!

Writing in a more concise way could avoid misunderstanding. If you want a proper answer to a specific question it is always a good idea to supply a diagram of the actual circuit rather than assuming you've described it unambiguously. What could "total load" possibly mean?
 
Also he could be more graceful in replying as he is the one that need help. I started out as a friendly joke, but no matter how I read the response, that didn't sound very friendly.
 
Kids these days!
 
sophiecentaur said:
Kids these days!

:smile::smile:
 
jim hardy said:
Is Superposition method stiill taught?

I was actually taken back a little...Is this a trick question or am I missing something? I actually went through Fourier Series etc. before I responsed! That's kind of got me into the joking mood!
 
  • #10
yungman said:
I was actually taken back a little...Is this a trick question or am I missing something? I actually went through Fourier Series etc. before I responsed! That's kind of got me into the joking mood!

It's bang right on as the way forward isn't it? You have to work out the answer in the frequency domain and then bung it all together together to find the time function.
 

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