Non-Inverting Op-Amp: Calculating Output Voltage

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Discussion Overview

The discussion revolves around calculating the output voltage of a non-inverting operational amplifier (op-amp) circuit. Participants explore the relationships between input voltages, resistances, and the impact of the resistor Rs in the circuit configuration.

Discussion Character

  • Homework-related
  • Mathematical reasoning

Main Points Raised

  • Participants present a circuit with a voltage supply of Vs = 100 mV, Rs = 1k, R1 = 1k, and R2 = 10k, powered by a ±15 V supply.
  • One participant expresses difficulty in understanding the role of the resistor Rs, noting that V+ = V- in an op-amp configuration, suggesting that finding V+ is crucial for solving the problem.
  • Another participant confirms the relationship V+ = V- due to the high open-loop gain of the op-amp and states that the input current of the op-amp can be assumed negligible, implying that Rs has little effect on the circuit.
  • There is a suggestion that the voltage at the V- terminal can be determined from Vs, leading to a voltage divider problem to find the output voltage.

Areas of Agreement / Disagreement

Participants generally agree on the fundamental relationships in the op-amp circuit, particularly the equality of V+ and V-. However, there is some uncertainty regarding the specific impact of the resistor Rs and how it influences the output voltage calculation.

Contextual Notes

The discussion does not resolve the specific calculations or assumptions regarding the voltage divider and the role of Rs in detail, leaving some steps and implications open for further exploration.

Who May Find This Useful

Students and individuals interested in operational amplifier circuits, particularly those working on homework or practical applications involving non-inverting configurations.

weedannycool
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Homework Statement


Calculate the out put voltsge on the amplifier with a voltage supply of Vs 100 mV and Rs = 1k , R1=1k R2=10k. power comes from a +-15 v supply


Homework Equations


V1-V2/r1+V1-V2/R2=0

V+=V-


The Attempt at a Solution



it is the Risistor Rs that i am have trouble with since V+=V- on an op amp if i can find V+ then i think it can be done.
 

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weedannycool said:

Homework Statement


Calculate the out put voltsge on the amplifier with a voltage supply of Vs 100 mV and Rs = 1k , R1=1k R2=10k. power comes from a +-15 v supply


Homework Equations


V1-V2/r1+V1-V2/R2=0

V+=V-


The Attempt at a Solution



it is the Risistor Rs that i am have trouble with since V+=V- on an op amp if i can find V+ then i think it can be done.

You correctly list V+ = V- which is true because of the high open loop gain of the opamp. The resistor Rs doesn't really do much in this circuit, since the input current of the opamp can be assumed to be negligible in a problem like this.

So you are given Vs, which goes right into the V+ input. What voltage will you therefore have at the V- terminal? From there, it's just a voltage divider problem, right?
 
thanks very much.
did u like my diagram?. definatly not going to be an artist. haha
 
weedannycool said:
thanks very much.
did u like my diagram?. definatly not going to be an artist. haha

Hey, it worked for me. And thanks for posting with the HH Template and showing your work. Made it much easier to help you out. Welcome to the PF!
 

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