/diy/ - Do It Yourself

>>1480650
I just can't seem to get the right answer now. REEEEEEE. Can someone please explain this problem to me? I am having trouble solving the problem. When I make the schematic in LTSpice it oscillates for awhile until it reaches a steady state voltage.

I am confused on how to go about mathematically solving this problem using the natural and step responses for an RC circuit.

I am using Vc(t) = Vinitial * e^(-t/2RC) for the discharging circuit and Vc(t) = Vinput - (Vinitial - Vinput)* e^(-t/RC). But when I try solving as if it is sequentially switching, the voltage just decays down to -20 V instead of hitting a steady state equilibrium.

To solve the problem I have assigned values, R = 10,000 Ohms and C = 0.00001 F. The time constants are 0.1 second (R) and 0.2 seconds (2R). This time constants is significantly larger than the half cycle which is 1 ms.

I think I am screwing up my initial condition. I have been using that Vc initial is 10 V because of KVL but I am not sure if that is correct. I am doing that because Vc(0-) = Vc(0+). After that I have just been slowly discharging and charging.

Given enough time in my excel sheet, it will just decay down to -20 V instead of reaching some steady state. What am I misunderstanding?