LM741 op-amp

[selim]

I know that in ideal-opamps the resistor Rs has no effect. But what is the purpose of using the Rs resistor in the circuit for LM741? Will there be any change if we increase or decrease the resistance Rs?

[rstofer]

https://electronics.stackexchange.com/questions/570426/why-put-a-resistor-in-series-with-the-positive-terminal-in-a-non-inverting-op-am

[Zero999]

R_S should be 800R, the nearest E24 value is 820R, but 1k is close enough. Actually, with these low values, it doesn't matter, because the bias current is small enough, the additional offset will be way below the 741's offset voltage.

[TimFox]

At low resistances, as pointed out above, the bias-current cancellation is rarely important when you do the arithmetic.
However, the 1k resistor on the + input may provide some protection against overvoltage (not much), since it will limit the current into the pin when the input voltage exceeds the common-mode range, or the voltage at the - input when the output reaches maximum.

[Terry Bites]

As noted, it helps reduce the effects of input bais currents.
In many appications this doesnt matter much becasue modern GP opamps tend to have very low bias currents.
Its good idea to add Rs in high gain and temperature sensitive applications.
If your feedback currents are of the same order as Ib, watch out!

RF, Video and Audio opamps designed for low impedance and low noise circuits may have very high bais currents.