Abstract: In this study, performance of piezoelectric piece which is converted an audio energy into electrical energy, was used to build mobile battery charger. The effective parameters on output power and the efficiency of system depends on the sensitive layer thickness of piezoelectric convertor, acoustic energy intensity and also the distance of the audio source and the device. Signals produced by piezoelectric convertors are weak and they will not be usability hence, AMP amplifier circuits are used to strength the generated signals. The simulation results show that AMP amplifier output has changes because of the audio energy alternation as well as the distance from audio energy source, so using MAX756 chip which is a switching DC-DC convertor of voltage step, we are tried to remove these changes on the output system. The proposed circuit will be very efficient to the rural regions and those where natural disasters have been occurred and there were no access to electric energy.