I have ciurcuit like below. I dont know why i have drop voltages on pointed places about 0,2 V. In real circuit I added resistors in the feedback loops of both last amplifiers to reduce the effect of the current flowing into the amplifier input, but it didn't have much effect.
Do you have idea what can I do to at least reduce these voltage drops?

 

I have no idea what you mean by "drop voltages" at the indicated points. You do know that opamps with zero volts differential on the inputs can have non-zero outputs. This parameter is usually characterized in the datasheets. The LM741 is an unusually crappy part in this regard along with all of its other manifest limitations. No sane person would use this part in a contemporary design.

It also looks like you expect this part to work in single supply mode. This part, LM741, was never designed or intended to work in single-supply mode. It must have bipolar supplies.

You need to get your head out of the dark place it is in and actually read and understand the datasheets of the parts you are using. There is really no excuse for what you have presented.

 

Sorry, I mislabeled the voltage drops. By voltage drops, I meant that the voltage at the output is lower than the voltage at the non-inverting input by about 0.2 V

I will have bipolar supplies, i only eddited this in simulation to test something

 

Sorry, I mislabeled the voltage drops. By voltage drops, I meant that the voltage at the output is lower than the voltage at the non-inverting input by about 0.2 V

What would you expect it to be in this situation where you are trying to use the LM741 in single supply mode? In this configuration the output CANNOT get all the way to 0. The only way this would be possible is for the negative supply pin to be lower than some small negative value.

 

Your V- is 0V. The output is 0.2V. This opamp (most opamps) cannot work near the supplies. Try making the bottom supply 5V.

 

I described the problem wrong, sorry. I meant the voltage difference between the non-inverting input and the output. Could it be because I power the amplifiers with unipolar voltage?

 

Please explain why you think that is important. WTH did you expect?
ETA: You still need to remove your head from the dark place it is in.
You have a DC input and you have DC outputs - what do you think is the problem. What kind of outputs do you want?

 

Each of your opamps has a gain of only 1. Since their inputs are biased at 0V and the negative supply is also 0V then the opamps rectify the input signal level that is higher than about 2V peak.
What is the 5.65 "somethings" input? It is not a microphone that needs lots of gain.
Why do you filter away all audio frequencies?

 

I power the amplifiers with unipolar voltage?

The data sheet on the LM741; the inputs need to be 3 volts away from the supply voltage(s) for the amplifier to work right. (2V typical 3V in some cases). You need a negative supply!
From the data sheet; with a 10k load the outputs will not work at the supply voltages. The outputs should not get to within 1V of -V and +V.

 

I have ciurcuit like below. I dont know why i have drop voltages on pointed places about 0,2 V. In real circuit I added resistors in the feedback loops of both last amplifiers to reduce the effect of the current flowing into the amplifier input, but it didn't have much effect.
Do you have idea what can I do to at least reduce these voltage drops?
View attachment 297525

Hello there,

Very nice drawing it is rare to see such neat drawings like that.

As others have pointed out, the 741 op amp is a very old op amp and even i don't like it even though i still like some other older op amps.
The reason is that it requires either two power supplies, one positive and one negative, or a single supply that is high enough. When you use a single supply though you have to know how to bias the circuit inputs so that it works as if it had dual supplies. For now you are probably better off using dual supplies as suggested elsewhere.

To make the point clear, the drawing is very nice and very neat but it is not worth considering the voltages you have outlined there because the circuit is known to NOT WORK AT ALL that way. This means the voltages you wrote on the schematic, at least for now, mean absolutely nothing, and you cannot gain much from having them verified because the circuit is not powered right yet.

This all means the first step is to improve the power supply situation by using a second supply that is negative. If you are using +15v then try adding a -15v supply with that and connecting that to the -V power terminals on the op amps. You should see a vast improvement.

I realize that you are new to this stuff, but when you use an op amp you have to check the data sheet carefully in order to use it right. If you miss something important the circuit may never, ever, work right.


Just to recap a little...

STEP 1:
Add a negative power supply and connect it to the op amps as appropriate.

STEP 2:
Take another look at the voltages and if you still have questions come back and ask.

 

Attach your LT SPICE file.