Electronic Musician on line has a four part historical overview of the role of electronics in music. Electronic music either begins with the bold but ill fated Telharmonium in 1906 or with Leon Theremin's inventive engineering school project that became know as the Theremin. The first commercially successful product was the Laurens Hammond's Model A using tonewheels that were refinements of the generators that were the heart of Cahill's Telharmonium. Hammond taught us the potential of the combination of innovative design backed up by solid production and business practices and intense marketing efforts. And an industry was launched.