Hello.

I would like to know if the main component of the first ciurcuit is a inverting operational amplifier or a differential amplifier.
And is it possible, if anybody could explain me the function of both circuits?
Thank you.

 

Welcome to AAC!

The opamp is an inverting amplifier. The transistor is able to drive a low impedance load better than the opamp.

Something like LM386 would be more appropriate.

 

Welcome to AAC!

The opamp is an inverting amplifier. The transistor is able to drive a low impedance load better than the opamp.

Something like LM386 would be more appropriate.

Thank you for your assistance.
I have a question about the inverting amplifier.
A square-wave voltage of 0-5 volts is applied to the first circuit.
Why is the output voltage of the amplifier -0,1 - + 0,1 V.
Is this due to the voltage divider that reduced the input voltage from 5 volts?

 

I should have asked before. Is this school work?

 

A square-wave voltage of 0-5 volts is applied to the first circuit.
Why is the output voltage of the amplifier -0,1 - + 0,1 V.
Is this due to the voltage divider that reduced the input voltage from 5 volts?

It is an inverting amplifier with a gain smaller than unity. An input between 0 and +5V would produce an output in the negative range only. However, if you need an output between -0.1 and +0.1 it is necessary to shift the output signal somewhat into the positive range. That is the purpose of the voltage divider which feeds the non-inv. input of the opamp.