The old training used to say "there are only three circuits, rectifiers,
amplifiers and oscillators". I wonder if that could be disproven today, think
about it, even a gate array in a computer is in some way a programmable
rectifier/selectable amplifier. Even the first amplifier could be switched off,
and even a digital two state bipolar device in a NAND gate is an inverting
amplifier, and several diodes (rectifiers) at the base will make it function as
the output stage of a NAND gate.

What's all this mean ? Think about even a pentium 4, cache, RAM all of it. Can
you really say there is a circuit other than a rectifier, amplifier or
oscillator ? Everything that followed is all a complex arrangement between
these three circuits.

Therefore another momentus occasion must be similarly observed, if one is to do
justice to history.

Who was it that first put a grid between anode and cathode ? Was it Lee
DeForest ? Whoever they were, this grid was just as important to electronics.
Otherwise we wouldn't have anything but diodes, we could charge up batteries
and run light bulbs or motors, but there would never be electronics without it
IMO. The idea that you could actually amplify a signal is what really kicked it
all off.

JURB