When Edison was denigrating alternating current, Tesla was perfecting the alternating current system, designing a more advanced, safer and practical alternating current generator.
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The engine must perform constant, controlled explosions with pistons, crankshafts, oil filters, alternators, fans, distributors, valves, coils, and cylinders among the many pieces of machinery needed for the work.
Westinghouse had refused to sell his AC generators to be used to kill, but Edison made sure that a Westinghouse AC generator was used when the first electric chair was being designed.