Boostor

Meet Boostor, a tiny three-legged transistor who lets a trickle of current control a flood.

A bipolar transistor has three parts called the emitter, the base and the collector. A small current into the base allows a much larger current to flow from collector to emitter. The ratio of the two is the current gain β.

A typical small transistor has β around 100. A base current of 20 μA then lets 2 mA flow through the collector. Wiggle the base current up and down a little, and the collector current wiggles a hundred times as much. That is amplification.

The base is very thin and only lightly doped, so most of the charge carriers that cross into it race straight on to the collector instead of leaving through the base.

The transistor was invented at Bell Labs in 1947, and John Bardeen, Walter Brattain and William Shockley shared the 1956 Nobel Prize in Physics for it. Billions of transistors now switch inside every phone.