Small changes to the voltage of the grid control large changes in the electron current flowing to the collector plate.

ECONOMIST: The middle age of the transistor

But the central point about both taps and transistors is that they allow a small signal the twist of a hand or the increase of a voltage to control a much larger one the rush of water or of electrical current.

ECONOMIST: The middle age of the transistor

GE, which supplies the National Grid operator in the U.K., would dearly love to outfit the U.S. network with control software and thousands of sensors to report voltage and other information on a second-by-second basis.

FORBES: Juicing the System