A classic example is Lilienfeld's transistor, in 1925.[1] He built the first three-terminal solid state device, a field-effect transistor, measured some gain, a

A classic example is Lilienfeld's transistor, in 1925.[1] He built the first three-terminal solid state device, a field-effect transistor, measured some gain, and patented it. But the materials to build better ones, and the theory for understanding what was going on, were decades in the future. Lilienfeld also invented the electrolytic capacitor, which was manufacturable at the time, so that was more immediately successful. [1] https://en.wikipedia.org/wiki/Julius_Edgar_Lilienfeld https://en.wikipedia.org/wiki/Julius_Edgar_Lilienfeld