I have the square wave output from a dc inverter circuit, and that is passed into a series resont circuit and a corresponding sine wave and voltage increase is available at the capacitor. Should I be able to bleed that voltage off the cap and rectify it and produce some useable dc current?

 

When you start a thread, post your circuit schematic in .png format as an attachment along with asking your question(s). Otherwise, we don't have a clear picture of what you're asking about.

 

Lets see the schematic. But probably not as loading the filter would probably destroy the response. But so what, just take the power from the square wave.