Hi all,

I have 10 units of the uA741 opamps, and I made a simple amplifier circuit with a power supply of 0 and +5V, and a gain equal to 2. No matter what the input signal is, the output is always equal to 5V.

I don't know what am I doing wrong, or could it be that all the opamps are bad?

The circuit works as it should be when using LM358P.

Any help is appreciated.

 

Welcome to AAC
Post Ur schematic

 

Two points:

First, a 741 op amp cannot operate on a total supply voltage of only 5 volts. It simply will not function, at least not in any usable fashion. Use an op amp designed to operate on low voltages, and consult the op amp data sheet for the details. Pay particular attention to input common mode range and output voltage range and make sure your circuit complies with those limits. In many cases, operating on only a 5 volt supply will require use of a rail-to-rail I/O op amp which can function with its inputs and outputs at any voltage between the voltages on the (+) and (-) supply terminals.

And second, no one here can give you ANY meaningful help until you post a complete, accurate schematic diagram of your circuit showing all components and their values and connections. Until you do that, we would be just guessing based on zero information.

 

Welcome to AAC
Post Ur schematic

Here it is.

 

Put a load on the output. It will no longer be 5V.

Bob

 

The lm741 needs a negative supply to make it zero output.

 

I suggest you (gasp) read the 741 data sheet.

 

Re-read OBW0549's post #3. That is the key to getting your circuit to work.

 

Hi all,

I have 10 units of the uA741 opamps, and I made a simple amplifier circuit with a power supply of 0 and +5V, and a gain equal to 2. No matter what the input signal is, the output is always equal to 5V.

I don't know what am I doing wrong, or could it be that all the opamps are bad?

The circuit works as it should be when using LM358P.

Any help is appreciated.

Look at the limitations for V in for the LM741. Running at 5 V doesn't give you much room to operate. It may not see an input voltage within 3 V of the low power rail or the high power rail. So at 5 V it probably won't recognize an input at all.
lm358, or other newer op amp, is much better.

 

Hi all,

I have 10 units of the uA741 opamps, and I made a simple amplifier circuit with a power supply of 0 and +5V, and a gain equal to 2. No matter what the input signal is, the output is always equal to 5V.

I don't know what am I doing wrong, or could it be that all the opamps are bad?

The circuit works as it should be when using LM358P.

Any help is appreciated.

 

Look at the limitations for V in for the LM741. Running at 5 V doesn't give you much room to operate.

Look again, running at 5V doesn´t give it ANY room to operate, as the minimum recommended supply voltage is a dual supply of +/-10V, or a single supply of 20V.

 

Got it, I think I just didn't read the datasheet carefully.

Thank you all.

 

Look again, running at 5V doesn´t give it ANY room to operate, as the minimum recommended supply voltage is a dual supply of +/-10V, or a single supply of 20V.

You are most correct, of course.