To his inquiring mind one of the instrument's weaknesses was its transmitter. Working alone in his rooming house he fashioned a new type of transmitter which he called a "loose-contact" transmitter, a type of microphone, which increased the volume of the transmitted voice. That he was able to do this while still possessing only a rudimentary knowledge of electricity and physics was quite astounding. When the members of the newly-formed American Bell Telephone Company were advised that a young and entirely unknown man in Washington had submitted a caveat (Berliner wrote it himself without the aid of a patent attorney) to the Patent Office covering a new transmitter, they could hardly believe it. Thomas Watson, the Mr. Watson of telephone fame, was sent to Washington to make inquiries. He returned such a glowing report of the transmitter and of Berliner himself that the company offered to buy the rights to the invention and to hire Berliner as a research assistant. For the next seven years, Berliner was employed by the ABT Co., first in New York City and then in Boston. During those years Berliner worked on numerous problems associated with the fledgling telephone industry and developed into a first-class theoretical electrician.
While working in Boston in 1881, Berliner became an American citizen and in the same year married a young woman of German descent named Cora Adler. In 1884 Berliner decided to set himself up as a private researcher and inventor, his cherished dream. He resigned from the American Bell Telephone Company and he and Cora left Boston and set up housekeeping in Washington, D.C.
In his small house in Washington, Berliner began working on additional improvements to Bell's telephone, selling the rights to his patents to the telephone company. Then in 1886 he began working on the invention that was to prove his most important contribution to the world. This was the development of the gramophone, the recording and reproduction of sound by means of disc records.
Among his other inventions were: