Hi Jake,

I was mistaken when I said your equation was incorrect. That's the equation I gave for a parallel RC circuit. The only difference being you are taking i[t] as a given and you are solving for v[t]. I didn't notice that they were the same equations in different form.

I think your notebook looks great.

Kind regards,

David

Hi Jake, I think your equation is incorrect. For parallel (trivial) and series RC circuits driven by an arbitrary v[t] I get the solutions below. (Sorry about Out[4] -- this new code system seems awkward at best.)

In[1]:= parallelEq = i[t] == c v'[t] + v[t]/r

Out[1]= i[t] == v[t]/r + c Derivative[1][v][t]

In[2]:= (* trivial *)
DSolve[parallelEq, i[t], t]

Out[2]= {{i[t] -> (v[t] + c r Derivative[1][v][t])/r}}

In[3]:= seriesEq = v'[t] == r i'[t] + i[t]/c

Out[3]= Derivative[1][v][t] == i[t]/c + r Derivative[1][i][t]

In[4]:= DSolve[seriesEq, i[t], t]

Out[4]= {{i[t] -> E^(-(t/(c r))) C[1] + E^(-(t/(c r))) \!\(
\*SubsuperscriptBox[\(\[Integral]\), \(1\), \(t\)]\(\*
FractionBox[
RowBox[{
SuperscriptBox["E", 
FractionBox[
RowBox[{"K", "[", "1", "]"}], 
RowBox[{"c", " ", "r"}]]], " ", 
RowBox[{
SuperscriptBox["v", "\[Prime]",
MultilineFunction->None], "[", 
RowBox[{"K", "[", "1", "]"}], "]"}]}], "r"] \[DifferentialD]K[1]\)\)}}

I am guessing from your wording that something didn't work, but I can't guess what.

Can you be much much more specific about what you want, what you did and what went wrong?

Or, if you start Mathematica fresh, type in the simplest example of exactly what you are trying to do, don't edit or replace or try again and again, just type (or paste, but even that can be more problematic) your problem, evaluate the whole notebook once, immediately save the notebook and attach that notebook to a post along with a clear simple verbal description of exactly what you were trying to accomplish and why it doesn't seem to be the result you were looking for then I'll give another try at what I hope will help you get where you want to go.

See if you can modify this

In[1]:= i[t] = 4; r = 2; c = 3;
sol = v[t] /. DSolve[{v'[t] == (1/c)*(i[t] - v[t]/r), v[0] == 0}, v[t], t]

Out[2]= {8 E^(-t/6) (-1 + E^(t/6))}

In[3]:= Plot[sol[[1]], {t, 0, 20}]

Out[3]= ...PlotSnipped...