There are several listed here: https://en.wikipedia.org/wiki/Electrostatic_generator https://en.wikipedia.org/wiki/Electrostatic_generator You might be thinki

There are several listed here: https://en.wikipedia.org/wiki/Electrostatic_generator https://en.wikipedia.org/wiki/Electrostatic_generator You might be thinking of the Wimshurst Machine: https://en.wikipedia.org/wiki/Wimshurst_machine https://en.wikipedia.org/wiki/Wimshurst_machine https://www.instructables.com/Small-Wimshurst-generator-from-cardboard-and-CDs/ https://www.instructables.com/Small-Wimshurst-generator-from... There are also mechanical variations on the Kelvin Water Dropper: https://en.wikipedia.org/wiki/Kelvin_water_dropper https://en.wikipedia.org/wiki/Kelvin_water_dropper I remember designing and building a machine that uses the principles of the Kelvin Water Dropper, but uses a belt instead of flowing water, and rearranges things to get asingle circle of motion instead of a "bowtie" or "figure of eight". But I expect you're thinking of the Wimshurst machine.