Hi, it is Wed morning. To continue, for a while, Spark Gaps were used but at the receiver, the diode detected the signal. Morse was used. By the 20th century, the vacuum tube arrived. Thnks to Edison for inventing the light bul which led to vacuum tubes. Receivers were built with vacuum tubes which has improved receiving tremendously. Then came the new transmitters. Vacuum tubes and no more huge sparks.

REFLECTION

     The transmitter and receiver were like a transformer. The Tx was the primary P and the RX was the secondary S.  It was air cored and the P and S were at great distances. Any current  induced in P will create a magnetic field around the coil and will radiate Electro Magnetic Waves. The S will sense the EMW and will absorb some energy from it. The further the S , the weaker the sensed current..

     The concept of the oscillator was born. To produce sine waves, a coil is paralleled to a condenser. A vacuum tube was used to continously pump current into this pair called a TANK CIRCUIT. The tank circuit has a unque behaviour in that the coil stores energy and transfers it to the capacitor. The capacitor then discharges into the coil. If not for the vacuum tube, the oscillation will decay. Evenrtually,semiconductors or transistors took over the job of the vacuum tubes. The tube/transistor  has basically three elements where one element can control the flow of current in the other two elements.This characteristic allows the oscillation to keep re triggering the tube/transistor.  Our first project is to demonstrate this oscillator.