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Topic: capacitor equation solution not working
Replies: 7   Last Post: Jun 22, 2011 6:33 AM

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Dana DeLouis

Posts: 97
Registered: 8/20/06
Re: capacitor equation solution not working
Posted: Jun 22, 2011 6:33 AM
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.... I[t_]:= If[t<10||t>60,0,1]

Hi. Just 2 cents for an alternative.
For a signal pulse, sometimes I'll remember it as follows:

What we have...
If[t<10||t>60,0,1];

FourierTransform[%,t,w]
(E^(35 I w) Sqrt[2/\[Pi]] Sin[25 w])/w

InverseFourierTransform[%,w,t]
1/2 (Sign[60-t]+Sign[-10+t])

Plot[%,{t,0,100}]

Or transformed into something like this:

f[t_]:=UnitStep[t-10]-UnitStep[t-60]
f[t_]:=UnitStep[-(t-10) (t-60)]

= = = = = = = = = =
HTH : >)
Dana DeLouis


On Jun 17, 12:09 am, "J and B" <noslow...@comcast.net> wrote:
> I am trying to solve a very simple circuit, one that has only a capacitor in
> it. What am I doing wrong? The final graph should show that the capacitor
> has discharged, but its staying constant. I have current starting at t=10
> and ending at t=60.
> I hope I have used the correct way to put in my code, I am using a new
> computer and I having trouble with my email program. Any advice would be
> appreciated.
>
> Thanks
>
> My code.
> I[t_]:= If[t<10||t>60,0,1]
> Plot[i[t],{t,0,100}]
> Eq=v'[t]==i[t]/c
> c=1;
> Soleq==v[t]/.NDSolve[{eq,v[0]==0},v[t],{t,0,100}],[[1]]
> Plot[soleq,{t,0,100}]






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