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Determining values of two 741 Op-amp resistors for inverting signal without gain

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johnfin

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How do I determine what values the 2 equal resistors should be for inverting a signal without gain. Also, should the ground of the 741 also have a resistor. I have seen some examples where that is called R3 and is equivilant to the parallel resistance of r1&r2.
 

741 Op-amp resistors

I read the article and that section. Very crypic and not easy to inderstand. I could not find a starting point for a 1:1 inverting signal. I guess I could start with two 1K resistors.
 

Re: 741 Op-amp resistors

I think you can use 1k and 1k, 10k and 10k - to - 100k and 100k.
Bye!!!
 

Re: 741 Op-amp resistors

Resistor selection depends upon your requirement. The formulas are avail which are used to find the value of resistence.
 

741 Op-amp resistors

Easiest way to choose is vakues whihc do not draw much current.

You must make sure that the assumptions of opamp (high i/p impedance) is followed.

Click on "Helped me" button if I helped you.
 

Re: 741 Op-amp resistors

The formulas are easy r2/r1 BUT knowing what they do is the problem. For plain inversion of the signal you want two of the same values for r1 and r2. Why use a resistor at all if the value will be 1. My signal is a 10ma modified square wave and I have tried two 1K resistors, and the output signal is not an inversion of the input signal. Also used r3(gnd) with a value of the parallel resistance of r1&r2 per the 741 spec sheet.
 

741 Op-amp resistors

A voltage follower can be BOTH inverting AND noninverting...

Have a go through Floyd...
 

741 Op-amp resistors

what are you trying to do? in general a 741 sucks at pretty much everything, the only real use i've ever found for them is when i needed a transistor level model since this is available for the 741
 

741 Op-amp resistors

That is true.. there are better and cheaper variants of 741
 

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