Transistors Changed Everything. Here’s How They Work

The article traces the transistor’s lineage from 19th-century electric relays, which used a control current to switch a larger circuit via an electromagnet, to vacuum tubes that emitted electrons from a heated filament to control current flow. It explains how these predecessors enabled long-distance telegraph signaling and early radios, setting the stage for modern transistors that power today’s computers, phones, and automotive systems.