This project is very easy to do!
Needed: An aluminum can. A sheet of copper foil of 0.3-0.4mm. Two insulating rubber spacers. An engine of a cd rom 2-3 volts, to be recovered from the inside of a PC. 1 liter of water with 3-4 tablespoons of salt for foods.The duration of rotation of the motor is approximately 7-8 minutes. When the salt water loses energy, it must be filled with fresh water and salt. For the success of this experiment it is necessary to have an engine that has a low power consumption 15-20 mA max and a voltage of 2-3 volts of a motor of a cd rom inside the pc. The use of engines for toys are not suitable for this type of experiment.
* The copper foil can't be replaced with other metals. youtu.be/6J5R9X8QrJA