Figure 3

As the FEP plastic ribbon flutters between the electrodes an alternating voltage and an alternating current are obtained oscillating between their positive and negative maximum values. The raw signal is after that fed into a bridge rectifier (GJB2508 from Diodes Incorporated) making the negative values positive. The figures show the rectified time evolution of (A) the voltage at 18 different wind speeds and (B) the current at 19 different wind speeds. We see that the voltages and current for the larger wind speeds and thus higher fluttering and signal frequency are not going all the way down to zero. Assuming a small effective smoothing capacitance of the rectifier could explain this effect (the data sheet gives the typical value 85 pF). The effect of a smoothing capacitor is expected to be larger at higher frequencies and this agrees qualitatively with the data in (A and B).