This Day in History
December 23, 1947
Bardeen and Brattain Demonstrate the Transistor to Bell Labs Supervisors
John Bardeen and Walter Brattain demonstrate the point-contact transistor, made from strips of gold foil on a plastic triangle, pushed down into contact with a slab of germanium. To measure the amplification they hooked up a microphone to one end of the device and a loudspeaker to the other. One by one, the men picked up the microphone and whispered, “Hello.” The loudspeaker at the other end of the circuit shouted, “HELLO!”. Although William Shockley had played a smaller role in the invention of the point-contact transistor, he was inspired by its promise, and devoted his time and efforts for more than a month to improving upon the device. By early 1948 he had devised the junction transistor, a device that shaped the design of nearly all transistors to follow.