Operational amplifier with feedback problem

In summary, The conversation discusses the correct placement of an op-amp's ro in a circuit and the implications of adding a resistance in parallel with an ideal voltage source. It is determined that, in this case, the Thévenin equivalent resistance would be zero as the resistance has no effect on the ideal voltage source. The individual also notes that guessing is not allowed when determining circuit values.
  • #1
TheRedDevil18
408
1

Homework Statement


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Homework Equations

The Attempt at a Solution


IMG_20161123_220433.jpg

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Using the equations above, I'm not getting the right answer for beta which is 0.4926 V/A.
Is my model wrong ?
 
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  • #2
The op-amp's ro should be shown in series with the controlled voltage source.
 
  • #3
NascentOxygen said:
The op-amp's ro should be shown in series with the controlled voltage source.
So with a voltage source, ro is always in series ?
 
  • #4
TheRedDevil18 said:
So with a voltage source, ro is always in series ?
Yes.

If you were to place a resistance in parallel with an ideal voltage source, what would be the Thévenin equivalent resistance of that combination?
 
  • #5
NascentOxygen said:
Yes.

If you were to place a resistance in parallel with an ideal voltage source, what would be the Thévenin equivalent resistance of that combination?

Would it be a voltage source in series with the resistance ?, I know that a current source with a parallel resistance is equal to a voltage source in series with that resistance
 
  • #6
TheRedDevil18 said:
Would it be a voltage source in series with the resistance ?
Guessing is not allowed.

Can you determine it?
 
  • #7
NascentOxygen said:
Guessing is not allowed.

Can you determine it?

Would it be zero ?, I determined it by using the rules. When you have a voltage source you short it and remove the load, so that means all the current will flow through the short and not through the parallel resistor
 
  • #8
TheRedDevil18 said:
Would it be zero ?, I determined it by using the rules. When you have a voltage source you short it and remove the load, so that means all the current will flow through the short and not through the parallel resistor
Right. A resistance has no effect if you erroneously add it parallel to an ideal voltage source: the effective source resistance here would stay as zero.
 
  • #9
NascentOxygen said:
Right. A resistance has no effect if you erroneously add it parallel to an ideal voltage source: the effective source resistance here would stay as zero.

Ok, thanks, I'll attempt the question again
 

1. What is an operational amplifier (op-amp)?

An operational amplifier, also known as an op-amp, is an electronic component that amplifies and processes electrical signals. It has two inputs, a positive and a negative, and one output. It is commonly used in electronic circuits for signal conditioning, filtering, and amplification.

2. What is feedback in an operational amplifier?

Feedback is a mechanism in an operational amplifier where a portion of the output signal is fed back to the input. This helps to control and stabilize the output signal, making it more accurate and reducing distortion.

3. What is the difference between negative and positive feedback in an operational amplifier?

Negative feedback is when the feedback signal is out of phase with the input signal, meaning it is inverted. This helps to stabilize the output signal and reduce distortion. Positive feedback is when the feedback signal is in phase with the input signal, amplifying it and potentially causing instability and oscillation.

4. What is the purpose of a feedback resistor in an operational amplifier?

A feedback resistor is used to control the amount of feedback in an op-amp circuit. It determines the gain of the amplifier and helps to stabilize the output signal. A larger feedback resistor will result in a lower gain and a more stable output.

5. What are some common problems that can occur with operational amplifier feedback circuits?

Some common problems that can occur with op-amp feedback circuits include instability, oscillation, and distortion. These issues can be caused by incorrect feedback resistor values, improper grounding, or improper input and output connections. It is important to carefully design and test op-amp circuits to avoid these problems.

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