Pulse Motors: MescalMotor w/ 2 Series LEDs on Piezo Output
The forward voltage of the LEDs, when they start conducting an appreciable current and lighting up, determines the voltage to which the capacitor will rise. With 2 LEDs in series this voltage is about 4 1/2 volts or so. The piezoelectric elements have no problem providing sufficient current to keep both LEDs lit and to sustain this voltage on the capacitor. The 470 uF cap is also sufficient to keep the LEDs lit for a few seconds after the motor is shut off (and correspondingly takes a few seconds to charge up in the beginning when power is applied to the pulse motor.)
