Non-Inverting Op-Amp: Calculating Output Voltage

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In summary, the problem involves calculating the output voltage on an amplifier with a given voltage supply and resistors. The resistor Rs does not play a significant role due to the high open loop gain of the opamp. The solution involves using the fact that V+ = V- and then solving a voltage divider problem. A diagram was also provided to assist with understanding the problem.
  • #1
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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  • #2
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?
 
  • #3
thanks very much.
did u like my diagram?. definatly not going to be an artist. haha
 
  • #4
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!
 

FAQ: Non-Inverting Op-Amp: Calculating Output Voltage

1. How do I calculate the output voltage of a non-inverting op-amp?

To calculate the output voltage of a non-inverting op-amp, you can use the formula Vout = (1 + Rf/R1) * Vin, where Rf is the feedback resistor and R1 is the input resistor. Vin is the input voltage to the op-amp. This formula assumes an ideal op-amp with infinite open-loop gain.

2. What is the purpose of using a non-inverting op-amp?

The purpose of a non-inverting op-amp is to amplify and buffer an input signal. It also provides a high input impedance and low output impedance, making it useful for applications such as signal conditioning and amplification.

3. How do I choose the appropriate values for Rf and R1 in a non-inverting op-amp circuit?

To choose the appropriate values for Rf and R1, you should consider the desired gain of the circuit and the input and output impedance requirements. The gain can be calculated by (1 + Rf/R1), so you can adjust the values accordingly to achieve the desired gain. Additionally, the values should be within the range of the op-amp's input and output impedance specifications.

4. Can I use non-ideal op-amps in my calculations for a non-inverting op-amp circuit?

Yes, you can use non-ideal op-amps in your calculations, but the results may not be as accurate as using an ideal op-amp. Non-ideal op-amps have limitations such as finite open-loop gain and input/output impedance, which can affect the output voltage calculation.

5. How can I ensure stability in a non-inverting op-amp circuit?

To ensure stability in a non-inverting op-amp circuit, you must ensure that the circuit meets the stability criteria set by the op-amp manufacturer. This includes maintaining a proper feedback ratio and avoiding frequency-dependent feedback networks. Additionally, you can use bypass capacitors to improve stability by reducing high-frequency noise and oscillations.

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