Luckily, shortly after, in 1906, American inventor Lee de Forest added a third " control" electrode that sits between the two electrodes in Fleming's design.

幸运的是，不久之后的 1906 年，美国发明家李·德富雷斯特参考弗莱明的设计，在两个电极间加入了第三个" 控制" 电极。