But a few researchers, seeing the analogy between them, tried to put a grid into the crystal detector to turn it, too, into an amplifying triode.

ECONOMIST: The middle age of the transistor

This was also a triode: a glass tube containing a heated metal filament which emits electrons, a plate that collects them once they have accelerated through the tube, and a metal grid in between.

ECONOMIST: The middle age of the transistor

To create the point-contact transistor, Shockley's team modified the cat's whisker by placing two fine metal wires close together on the surface of a germanium crystal, turning it from a diode into a triode.

ECONOMIST: The middle age of the transistor