I've got a homework to solve this circuit by a thevenin's theorem and get a current and tension of the diodes using graph. I've looked all around the Internet and couldn't find one single video that does the same thing. Can anyone help me please ? Things that I know : U=10V,R1=10Ω,R2=20Ω, R3=30Ω
My approach to this would be as follows
Create VI curve for D2 in parallel with R3 since we are given a VI curve for D2 and we now the current in R3 from ohms law
Add that to the VI curve for D1 to get the VI curve for D1, D2 and R3 combination.
Work out the Thevenin equivalent of R1, R2 and U1.
Plot a load line with this and our combined VI curve to find the voltage at the anode of D1 and the current in D1.
From current in D1 we can find its volt drop and from there the voltage across D2 and the current in both D2 and R3.
The voltage across each diode should be constant, probably about 0.7V but look it up in your assignment. Give it a little thought, and this should already give you the current and voltage on R3.
Now convert R1/V into a Norton equivalent, and add R2 in parallel...you know the voltage and combined resistance, right? You can figure out the current in that resistor combo.
Any current that doesn't go through R1/R2 will go through D1. Whatever part of that that doesn't go through R3 goes through...?