Electrical – How to get the 741 op amp to work as a linear amplifier

operational-amplifiersignalvoltage

I'm trying to run the 741 as a non inverting voltage amplifier.

I did the circuit in proteus simulation and it works well to get 2x the input signal.

For example, if input voltage is 1V, then I get 2V on output pin.

So for this implementation, I the same circuit on the breadboard:
741 op amp proteus simulation photo

But on the breadboard, I connected the exact circuit but it doesn't work as expected!!

This is my video on YouTube explaining the problem:

ua741cn non inverting amplifier problem

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I have another question:

Can I use 12V source and split that by two 10k resistors and supply +6V and -6V to the op amp like this circuit:

positive and negative voltages from 12V power adapter

Best Answer

5V is not enough for the LM741 to work properly. It needs a minimum of +/-5V

Also the input common mode range does not include the negative rail, so the inputs are not going to be functional.

The output can typically swing okay to +2 with a light load (though 667 ohms is not a very light load if the voltages get higher), so at least that part is okay (at room temperature).

You could plop down a different op-amp and it would work more-or-less as you intended, but this way you are learning something. Many very useful modern op-amps have limited input common mode range, and you should always pay attention to datasheet power supply limits (and output swing and loading guarantees).


Give it +/-5V supplies and it should work properly, but it would be better to increase the feedback resistors to somewhere in the 10K range.

To stay within datasheet guaranteed numbers, as a pro would normally seek to do, increase the supply to +/-10V and make sure the load resistance is at least 2K (including the loading of the feedback network). That should guarantee a +/-5V output range over the full temperature range of the chip.

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