There is a software which you might already know about, but I want to share it for everyone's benefit. It is called MicroCap . It is used to build electrical circuits. You can plot relationships between voltage, current, power, etc with time, frequency and so on. For more information click on here
The student version is free to download of course in limitations to the number of electrical componet s you may have in a page.
Let us know if you have any experiences with the program