Hello, I have some question about the circuit i posted as photo file. I have there a AC source 4V amplitude. R= 100k ohm. Uv=1.5v. RB=680k ohm. I know that diode flows current at one direction. And when u have AC source you have either a only positive voltage through a diode or a only a negetive voltage. But I dont understand the circuit when you have a DC source of 1.5V for first part and then 4.5 V for second part.
I did the simulation of the two parts: The green one is AC signal and the blue one is de voltage through de Resistor 680K ohm. But I dont understand the working of this circuit? Can someone please explain me this circuit.