The capacitor operates in an identical fashion to a sliding variable capacitor. The total area of overlap will be no more than 36cm, so the total capacity of the capacitor is likely to be in the nanofarad range. I was going to use a pulse generator on like a 15 milisecond delay between pulses. So I am thinking that tying the frequency to the pulse generator would make for a workable setup. This would make for a 66.6 Hz setup.
I was going to use a 3.7V 150mAh Lipo Battery for power due to size constraints.