Transistor. Transistor from the late 1990s rests on a fingertip. Transistors have many uses in electronic equipment including electrical amplifi- cation and signal processing. Transistors have three wires attached to them - known as the base, collector & emitter. These are attached to sect- ions of semiconductor in the transistor which have precise levels of impurities to determine their electrical properties. The amplification of the current from emitter to collector is determined by the voltage of the base wire. Transistors have allowed the miniaturisation of electronic compo- nents. The first transistor was invented on 23 December 1947 by Bardeen, Brattain and Shockley.