The Dawn of Amateur Radio in the U.K. and Greece | Page 5

are widespread and staggering in their immensity. But we must not forget that popular demand for this convenient form of power arose only about 100 years ago, mainly for illumination.
Recent experiments in superconductivity, using ceramic instead metal conductors have given us an exciting glimpse into what might be achieved for improving efficiency in the distribution of electric power.
Historians of the future may well characterise the 20th century as `the century of electricity & electronics'. But Edison's D.C. generators could not in themselves, have achieved the spectacular progress that has been made. All over the world we depend totally on a system of transmitting mains electricity over long distances which was originally created by an amazing inventor whose scientific discoveries changed, and are still changing, the whole world. His name was scarcely known to the general public, especially in Europe, where he was born.
Who was this unknown pioneer? Some people reckon that it was this astonishing visionary who invented wireless, remote control, robotics and a form of X-ray photography using high frequency radio waves. A patent which he took out in the U.S.A. in 1890 ultimately led to the design of the humble ignition coil which energises billions and billions of spark plugs in all the motor cars of the world. His American patents fill a book two inches thick. His name was Nicola Tesla (1856-1943).
Nicola Tesla was born in a small village in Croatia which at that time formed part of the great Austro-Hungarian Empire. Today it is a northern province of Yugoslavia, a state created after the 1914-1918 war. Tesla studied at the Graz Technical University and later in Budapest. Early in his studies he had the idea that a way had to be found to run electric motors directly from A.C. generators. His professor in Graz had assured him categorically that this was not possible. But young Tesla was not convinced. When he went to Budapest he got a job in the Central Telegraph Office, and one evening in 1882, as he was sitting on a bench in the City Park he had an inspiration which ultimately led to the solution of the problem.
Tesla remembered a poem by the German poet Goethe about the sun which supports life on the earth and when the day is over moves on to give life to the other side of the globe. He picked up a twig and began to scratch a drawing on the soil in front of him. He drew four coils arranged symmetrically round the circumference of a circle. In the centre he drew a rotor or armature. As each coil in turn was energised it attracted the rotor towards it and the rotary motion was established. When he constructed the first practical models he used eight, sixteen and even more coils. The simple drawing on the ground led to the design of the first induction motor driven directly by A.C.electricity.
Tesla emigrated to the U.S.A. in 1884. During the first year he filed no less than 30 patents mostly in relation to the generation and distribution of A.C. mains electricity. He designed and built his `A.C. Polyphase System' which generated three-phase alternating current at 25 Hz. One particular unit delivered 422 amperes at 12,000 volts. The beauty of this system was that the voltage could be stepped down using transformers for local use, or stepped up to many thousands of volts for transmission over long distances through relatively thin conductors. Edison's generating stations were incapable of any such thing.
Tesla signed a lucrative contract with the famous railway engineer George Westinghouse, the inventor of the Westinghouse Air Brake which is used by most railways all over the world to the present day. Their generating station was put into service in 1895 and was called the Niagara Falls Electricity Generating Company. It supplied power for the Westinghouse network of trains and also for an industrial complex in Buffalo, New York.
After ten years Tesla began to experiment with high frequencies. The Tesla Coil which he had patented in 1890 was capable of raising voltages to unheard of levels such as 300,000 volts. Edison, who was still generating D.C., claimed A.C. was dangerous and to prove it contracted with the government to produce the first electric chair using A.C. for the execution of murderers condemned to death. When it was first used it was a ghastly flop. The condemned man moaned and groaned and foamed at the mouth. After four minutes of repeated application of the A.C.voltage smoke began to come out of his back. It was obvious that the victim had suffered a horribly drawn-out death.
Tesla said he could prove that A.C. was not dangerous. He gave a demonstration of high voltage electricity flowing harmlessly over his body. But in reality, he cheated, because he had used a frequency of 10,000