I can't find the problem. 2 stages amplifier with op amps.

Thread Starter

Elena Grigorița

Joined May 8, 2019
11
I have the following circuit. I have some problems and I can't identify the reason.
1.Why I have such a distorsioned output voltage?
2.Why Vmax is aprox is 25V ,but Vmin is 29V?
 

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bertus

Joined Apr 5, 2008
20,041
Hello,

There is an offset at the input of the opamp.
In your schematic it shows as -1.53 volts at the output.
This will shift the complete signal down.

Bertus
 

bertus

Joined Apr 5, 2008
20,041
Hello,

The LM741 has an offset, this will be amplified by the second amplifier.
The LM741 has the possibility of offset compensation:

LM741_offset_compensation.png

Bertus
 

bertus

Joined Apr 5, 2008
20,041
Hello,

You have only connected a resistor.
The schematic shows a potmeter with the wiper to the - powersupply.

Bertus
 

bertus

Joined Apr 5, 2008
20,041
Hello,

You connected the wiper to ground.
It should be connected to the -15 Volts.

Bertus
 

bertus

Joined Apr 5, 2008
20,041
Hello,

The position of the wiper will influence the offset.
When it is in the middle it will be like the potmeter is not connected.

Bertus
 
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