Before tubes came around, there was a man who was fascinated with the buzzer. MORSE. He asked his assistant to make combinations of the short and long buzz to be called dot and dash. The Morse Code! he probably didn't realized that he had stumbled on BINARY since he also used two symbols only, dot and dash, 0,1, not there and there. So, all over America there was a pair of wires along the railroad tracks carrying the Morse Code! Another man , BELL, wanted to send his own voice over a pair of wire. He made a speaker, moving coil with a cone. Then he sent electric current to it via a carbon tip touching a paper diaphram. When he spoke on it, it vibrated and the current running through the wires vibrated correspondingly. The TELEPHONE!


CONTROLLING ELECTRICITY

     It was all because of Edison's light bulb! After Edison invented the light bulb, other experimenters like Lee de Forest played around with the bulb. The DIODE was discovered via an vacuum tube. Electrons flowed from the heated element called the Cathode to a Plate but not the other way around. Then when a thord element was put between the Cathode and Plate, to be called the Grid, electron flow from the Cathode to the Plate can be controlled by a tiny current on the grid. The TRIODE, an amplifier!

     MAN went to WAR in 1917 with internal combustion engines on biplanes, with machine guns in front of the pilot.. In 1938 when Germany invaded Poland, WW2 began and MAN had vacuum tubes! The famous walkie talkie of the US army, backpacks with long antennas. Vacuum tubes.  The Germans used them in their V-1 rockets send to England. There were Pentagrid tubes.

     Then Peace in 1945. The Americans at the Bell Labs in California discovered SEMICONDUCTORS. The original material was the GERMANIUM. And they were PNPs! It was developed in 1949 and by the early fifties, a Japanese company called SONY corporation made the pocket radio, an AM BC radio working on batteries!

     Communications technologies were developed during the tube era. Superhet for tube receivers, vacuum tube analog computers. These technologies simply were applied using semiconductors called transistors.


WHY WERE THEY CALLED VALVES?

      It was because they were valves controlling the flow of electrons! The transistors are still valves not requiring heaters. The Emitter-Collection junction is controlled by teh Base Emitter junction. Tickle the Base and electrons flow in the E-C junction!


Now, what is WIRELESS?

      In Europe before tubes and transistors were around, they experimented with SPARK GAPS. It was like lighting matches. The electric spark spewed waves of many frequencies. It was NOISE! Electrical noise. The receiver was a simple glass tube filled with iron filings. The filings aligned themselves when a spark occurred. Contact was made and it was a simple switch! Aha, WIRELESS. In the meantime, the mathematicians like MAXWELL in England theorized that signals can travel in space and information can be imbedded in it by changing the signal strength. Aha, AM!


RESONANCE

     Get a pair of tuning forks of the same note, bang one and the other one RESONATES! PHYSICAL RESONANCE! The frequency was within the human hearing range.