I'm attempting to construct a demo using an LRC circuit. Here's the setup: I currently have three 1000 microF capacitors which I plan to wire in parallel for a combined capacitance of 3000 microF. (maximum voltage for this is 35V, but that shouldn't be a problem). I could get more capacitors if I really need them, but the local Radioshack seems to be charging exorbitant rates ($1.61 for a 1000 microF capacitor, 35V) and I would prefer to keep costs down if possible. I plan on winding 30 gauge wire around a galvanized steel landscaping spike (6" long, ~1/2" diameter IIRC) to create an inductor - assuming that's feasible. The setup would go like this: The three capacitors are wired in parallel to work as one capacitor, which will be wired in series with the inductor. There will be a switch that will, in one position, complete the circuit by including a nine volt battery, and in the other position will complete the circuit without the battery (just the inductor and capacitor). A basic LRC circuit. When the power is shut off, the capacitor will discharge, and then back emf from the inductor will charge the capacitor up again, etc, until everything is lost to joule heating. I would like this period to be approximately 5 seconds, but I would consider two or even one acceptable - I just don't want it to fly by real fast, because it's for a demo. I looked for some equations on the internet, and used them... it told me I needed some incredibly huge number of windings - infeasible. I have a lathe that I can use to wind wire around this spike, but there are limits of course. Something didn't seem very right about that, so I tried again with some other equations I found, and got an even more ridiculous 1.2 windings - obviously that's not going to do it. Does anyone know how to do the calculuations I want? I would really appreciate some numbers that I could use for this: C, R (if that matters), L (preferably in the form of number of windings needed), and anything else that I'm missing. Thanks.