Nikola Tesla

Nikola Tesla    1856 - 1943
Excerpt from "Much Ado About Almost Nothing":

Nikola Tesla was born in 1856 in what is now Croatia, but was then part of the Austro-Hungarian Empire.  He was a strange boy with few friends.  At school he was brilliant in languages and superb in mathematics; he irritated the teacher and the rest of the class by having the answer before the teacher even finishedstating the problem.  

He often experienced images in his mind, sometimes preceded by a flash of light.  The images were so vivid that he could touch them with his hand and was unable to tell whether they were real or imagined.  He went on mental journeys, saw new places and countries, lived there, met new people and made new friends.  These journeys were as real to him as if he hadactually traveled there.  At 17 this mental imagery transformed itself gradually to invention: he was able to picture novel machinery in great detail and in full operation.

       At age 19 he entered a polytechnic school in Graz, Austria.  At first he studied intensely, getting up at 3 a.m. and working until 11 p.m. seven days a week.  One teacher became worried that Tesla was damaging his health andwarned his parents.

       During Tesla's second year at Graz the school received a small electric generator for classroom demonstrations.  As all generators of that time it had a ring of contacts on the rotating part, which switched the polarity back and forth so that the output was converted to DC.  Tesla observed the sparking, noisy and smelly contacts and proclaimed that they were notnecessary.  He got into an argument with the teacher, who proceeded to demonstrate that without these contacts the generator could not possibly work.

       In his third year Tesla became bored with school, started gambling, got poor grades and flunked out.

       At 24 he started again at the University of Prague, but left after only one term, without getting a degree.  He then moved toBudapest and worked as a draftsman at the Central Telegraph Office.  He had been thinking about the generator in Graz and how the contacts could be eliminated.  The problem haunted him and started working long hours again to come up with a system that was purely AC.  Deprived of sleep, he had a nervous breakdown.

       In early 1882, at age 25, the solution came to him in a brief flash: there neededto be not just one winding on the generator, but several (he eventually settled on three).  As the rotor turned the first winding would reach its peak, followed by the second and the third and then the first one again.  In the motor, which was almost identical to the generator, again three coils were used.  If the rotor consisted of a permanent magnet, it would follow the rotating magnetic fieldof the windings. With two "phases" (i.e. coils) the direction of the rotor was uncertain, it could turn either way; with three the direction was assured.

       But he didn't stop there, he added his most important invention: if the rotor was made of soft iron and was wound with its own coil with the ends connected together, the rotating magnetic field produced by the stationary part wouldinduce a voltage in the inside coil, which in turn would create its own magnetism.  The rotor thus would start turning in the direction of the rotation.  If it turned more slowly than the field, the induced power would be large, gradually decreasing as the mechanical rotation approached the electrical one.  Thus such a motor produced a lot of power during start-up, a highly desirable feature.  And therotor needed no contacts.

       Tesla did all of this in his head; he didn't need to make any drawings.  He could operated the system in his mind, detect flaws and optimize performance.

       In April 1882 Tesla moved to Paris to work for Edison Continental.  He tried to interest the company in his AC ideas, but found no response.  In the summer of 1883 his assignment was to fix a power...