Electrical circuit design questions
There are software programs called circuit simulators that will let you experiment with circuits to your hearts content. Once such is called LT Spice and can be downloaded for free from the Analog/Linear web site. Once you have this tool installed you can then use the schematic editor to enter a circuit that you find someplace - or one that you devise yourself - and then use the tool to calculate everything and even show you timing diagrams of the circuit responses. 

If you use your search engine you can also find a Yahoo user group for LT Spice that you can join and find lots of useful information about using the tool in more advanced ways.