1. The problem statement, all variables and given/known data Task is to write differential equation for this circuit. 2. Relevant equations 3. The attempt at a solution I'll try to solve the task, but now I want to know, is it possible to use voltage source instead of current source. For example, I can calculate ekvivalent resistance R_1, R_2 an R_3 parallel. Then current source * ekvivalent (total) resistance = voltage source? Like this: Don't look at numbers, they are random.. I just want to know about idea. If it's possible, then I can use V(Thevenin) and R(Thevenin). OR: I can calculate R(Thevenin) = (R2*R3)/(R2+R3), I guess. But I don't know, how to calculate I(Thevenin). Or I have to use Northon method, when we've got capacitor? Can you suggest something?