The LEGO-Based Tables are powered by batteries driving the motor at a constant speed. The External Power Supply add-on enables driving the motor using wall power and provides the ability to make fine adjustments to rotation rate. These features are beneficial for experiments such as Taylor Columns that require either a low rate of rotation or precisely changing speed mid-experiment. Disclaimer: Be careful with experiments involving wall power and water in close proximity. We include a GFCI in the required components for safety.
