How to calculate op amp output voltage?

[Blue10]

Hello everyone,
Please help me find the output voltage formula for this operational amplifier circuit.

Thank you.

 

[KlausST]

Hi,

R1 is useless.

Klaus

 

[Blue10]

Hi,

R1 is useless.

Klaus

Does this mean that this is a non-inverting amplifier circuit?

 

[KlausST]

Hi,

I've just seen the schematic ...
you have a simulation tool. Why don't you try it? ;-)

Klaus

 

[albbg]

If the op-amp is ideal (or close to be ideal), in the linear range the voltage at the inverting input equals the voltage at the non-inverting input so R1 is short-circuited by the behavior of the op-amp itself.

 

[LvW]

If the op-amp is ideal (or close to be ideal), in the linear range the voltage at the inverting input equals the voltage at the non-inverting input so R1 is short-circuited by the behavior of the op-amp itself.

I know and realize that - as it seems - the question comes from a beginner.
And - as far as an idealized opamp is concerned - I agree to your answer.

However, for real opamps with a frequency-dependent gain the resistor R1 is NOT useless. It resembles a special kind of external frequency compensation - thereby improving the phase margin as well as the step response. More than that, using such a resistor across the opamps input nodes allows us to use opamps which are not unity-gain stable even with 100% feedback (unity gain).

 

[KlausST]

Hi,

I agree. But I doubt that's the OP's question, or can gain some help from this information.

Klaus

 

[LvW]

Hi,
I agree. But I doubt that's the OP's question, or can gain some help from this information.
Klaus

OK - I agree.
On the other hand, if I read something that is not quite correct, can it then be a mistake to correct or complete it?
Maybe it is a good hint - even for the beginner - that circuits can behave completely different under real conditions if compared with idealized models.

 

[KlausST]

Hi,

No, please keep on correcting mistakes. We (the forum) don't want to spread mistakes.
I'm not free of mistakes - and I'm curious to learn new things every day.
So, everything is fine. I can stand being corrected.

Klaus