I recently simulated a parallel resonant tank circuit on multisim. I put an oscope across the tank circuit and I get an AC signal, but what interests me is that it is amplitude modulated. The oscillations slowly build up in amplitude, hit a peak and then die back down. I think that the increased amplitude is due to the inductor and capacitor charging, once they hit their peak charge no more energy is input from the source and the energy begins to slowly dissipate.....Until it reaches a point where it begins to charge again......Is this close at all to what is going on? Can anyone explain to me why the AC signal has amplitude modulation?