To make a red LED glow, what was the approximate voltage produced in the piezoelectric generator

The voltage required to light up a red LED typically ranges from 1.8 to 2.2 volts. However, the voltage produced by a piezoelectric generator can vary greatly depending on the specific design and how much mechanical force is applied to it. Therefore, without specific information about the piezoelectric generator used, it's difficult to provide an exact voltage. But it would need to generate at least enough voltage to meet the LED's forward voltage requirement, which is around 1.8 to 2.2 volts for a red LED.