Energy harvesting engineering field constitute a promising area to provide electrical power for low-power electric applications obtained from other sources of energy available in the environment such as thermal, electromagnetic, vibrational and acoustic by using transducers. Vibrational sources stand out as a main alternative to be used for generating electric power in sensor nodes, microelectronic devices due to greater energy conversion efficiency and the use of simple structure. The cantilever is the main system implemented in studies of obtaining electric energy from vibrations using piezoelectric transducers. Most of piezoelectric transducers in the literature are not yet commercially available and / or are difficult to access for purchase and use it. This paper proposes the characterization of low-cost piezoelectric transducers, configured as sensors, for Energy Harvesting applications using three different sizes of circular piezoelectric diaphragms (diameters: 3.4cm, 2.,6cm and 1.5cm) PZTs. For all three different PZTs it was found that the maximum power transfer occurs for a resistive load of 82kΏ. The maximum power generated in the load for the three PZTs was 40uW, 14uW and 1.4W, RMS voltages 1.8V, 1.0V and 0.34V, acceleration of 1.3g and at vibration frequency approximate of 7Hz.