Internal resistance seen by the voltage source, Vx?

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SUMMARY

The discussion centers on calculating the resistance seen by the voltage source, Vx, in an ideal op-amp configuration. The calculated resistance is 3 kΩ, derived from analyzing the circuit's input resistors and their arrangement. Participants emphasize the importance of correctly labeling the current flow through each resistor to facilitate accurate calculations. The conversation highlights the need for clarity in notation and understanding of circuit principles to arrive at the correct resistance value.

PREREQUISITES
  • Understanding of ideal op-amp configurations
  • Knowledge of resistor networks and their calculations
  • Familiarity with current flow notation in circuit analysis
  • Basic principles of electrical resistance
NEXT STEPS
  • Study the principles of op-amp circuit analysis
  • Learn about resistor combinations in series and parallel
  • Explore current flow notation and its significance in circuit diagrams
  • Investigate the impact of feedback on op-amp performance
USEFUL FOR

Electrical engineering students, circuit designers, and anyone involved in analyzing op-amp circuits will benefit from this discussion.

Kratos321
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Hi everyone,

I have attached an image of the op-amp configuration (all op-amps are ideal). Basically, the question asks to calculate the resistance seen through the voltage source. The answer is 3 kΩ but I just don't understand how this is found. If someone could assist me, I would really appreciate it.

(By the way, I mean just resistance in the title, not internal resistance)

Cheers
 

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You have labelled the current flowing in that top 1k resistor as Ix. Using the notation you have established, now mark in the magnitude and direction of the current in each of the other 4 input resistors.
 

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