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Above schematics is just a representation of an OpAmp circuit coupled to a measuring device. Imagine we know the values of the following parameters: Vcc, Vout, R_feedback and R_measuring device. R_measuring_device can be the input impedance of a scope or a DAQ hardware. V_out is the output voltage of the circuit which is coupled to a voltage divider in the schematics.
If one wants to couple V_out to the measuring device, one may need to scale V_out in many cases(for example to lower the voltage). In this case the ratio of R1 and R2 matters and by selecting the right ratio we can scale the output voltage. So far I understand..
But we don't choose in real life R1 = 22 ohm and R2 = 10 ohm for instance. I mean the ratio is easy to figure out when we aim to scale the voltage, but how about the optimum resistor values for R1 and R2?
What is the criteria here? Okay I might guess if R1 and R2 is too small, the OpAmp could be loaded with too much current? But how to quantify the R1 and R2 to prevent it to load. Should we check the max current output of this OpAmp from the schematics?
Same confusion with the relation of R1 and R2 with input impedance of the measuring device(R_measuring_device). If R1 and R2 are too big or too small it could be problem?
And there is also a relation or limitation to R1 and R2 coming from R_feedback I guess. Is that right? R_feedback is connected to the output of many opAmp circuits? Does R_feedback have effect on choosing R1 and R2 values?
These all three things are in relation with R1 and R2 here. How can one quantify R1 and R2 considering surrounding resistors are known(R_feedbcak, R_measuring_device) as well as Vcc and V_out are also known? Is there a rule of thumb or a practical easy way?