Good Morning. It is Tuesday Morning, Oct. 14, 2014

Well, I discussed waves and resonance.  Human ears can hear up to the khz range only. electrical waves came to be know as Electro Magnetic Waves. We all know that magnetism and electricity are inter-related.
magnets can generate electricity and vice versa.

A bit of history. Man was amazed by  lightning but in the old days, didn't really understand it, much less harness it. In the 19th century, Man began creating mini lightnings in the form of sparks. A spark sent out waves of different frequencies. It was like a shotgun. It was discovered  that these waves were also magnetic. Iron fillings inside a glass tube aligned and freeze up in the presence of these waves. The transmitter was called the SPARK GAP and the Receiver was called the COHERER TUBE. Since the fillings lined up and made contact with one another, electrical conduction took place. The first transmitter and the first receiver were conceptualized and were actually made. A man actually controlled a floating balloon inside a theatre controlled by these TX and RX! Single channel and very broadband. From 1886 to 1916, telegraphs used Spark Gap transmitters. Marconi used this type of transmitter to send a telegraph message across the Atlantic.

Then the Galena crystal! The Galena Crystal was the first semiconductor device. It was a Schottky Hot Carrier Diode! It converted the Alternating RF current to Pulsing DC, pulsing based on the modulation at the TX.