How is a telephone made?

History

Throughout history, people have devised methods for communicating over long distances. The earliest methods involved crude systems such as drum beating or smoke signaling. These systems evolved into optical telegraphy, and by the early 1800s, electric telegraphy. The first simple telephones, which were comprised of a long string and two cans, were known in the early eighteenth century.

A working electrical voice-transmission system was first demonstrated by Johann Philipp Reis in 1863. His machine consisted of a vibrating membrane that opened or closed an electric circuit. While Reis only used his machine to demonstrate the nature of sound, other inventors tried to find more practical applications of this technology. They were found by Alexander Graham Bell in 1876 when he was awarded a patent for the first operational telephone. This invention proved to revolutionize the way people communicate throughout the world.

Bell's interest in telephony was primarily derived from his background in vocal physiology and his speech instruction to the deaf. His breakthrough experiment occurred on June 2, 1875. He and his assistant, Thomas Watson, were working on a harmonic telegraph. When a reed stuck on Watson's transmitter an intermittent current was converted to a continuous current. Bell was able to hear the sound on his receiver confirming his belief that sound could be transmitted and reconverted through an electric wire by using a continuous electric current.

The original telephone design that Bell patented was much different than the phone we know today. In a real sense, it was just a modified version of a telegraph. The primary difference was that it could transmit true sound. Bell continued to improve upon his design. After two years, he created a magnetic telephone which was the precursor to modern phones. This design consisted of a transmitter, receiver, and a magnet. The transmitter and receiver each contained a diaphragm, which is a metal disk. During a phone call, the vibrations of the caller's voice caused the diaphragm in the transmitter to move. This motion was transferred along the phone line to the receiver. The receiving diaphragm began vibrating thereby producing sound and completing the call.

Source: Answres