The Original LED (Light Emitting Diode)

In this post I attached an example of a vacuum tube rectifier. In classic electronics a rectifier is also know as a diode. In most vacuum tubes was a heating element that glowed or a plasma gas that glowed, thereby giving off light. Therefore, this could be called a light emitting diode, or an LED. Of course this is not exactly what we mean these days as LEDs are typically used to indicate something, like power is on or a fault or an audio level. Still, this could be the "original" LED. Really, it could.