From the telegraph to the phone
Alexander Graham Bell was able to invent the telephone after he attempted to develop the telegraph and the telegraph as a means of communication thirty years before the invention of the telephone and, despite his successful system, he limited himself to sending and receiving a message simultaneously, then Bell worked on the possibility of transmitting multiple messages simultaneously and through the same thread, and in March of the year 1875 AD. Bell met Joseph Henry, director of the Smithsonian Institution, where Joseph heard his ideas over the telephone and encouraged him to work on them, and after the development of the telegraph in June 1875. it was discovered accidentally that sound could travel through wires, and then Thomas started Watson and Bill to invent the Telephone, the first phone call between them came when Bell spoke to Watson on the phone saying, “Mr. Watson, can I come here, do I want to see you?” Watson then announced that he had heard it and in March 1876 Bell obtained a patent for his device, so that it quickly began to spread.
The first regular telephone was made in New Haven in 1878 and the phones were rented in pairs to subscribers, as one subscriber had to set up their own line to communicate with the other subscriber, and in 1889 AD Strugger invented a converter that could connect a single line to one of the lines up to the percentage.
Cordless phones are phones that allow them to be used freely within a limited distance of up to 100 meters. The first devices used an analog signal system operating on a pair of frequencies (1.7 and 49 MHz) and, in the early 1980s, cordless phones operated on frequencies in both bands (46 and 49 MHz). . And, in the late 1990s, it became operational in both bands (902 and 928 MHz). These phones also use analog or digital signaling technology or spread spectrum technology.
The foreign company Motorola is the world’s largest mobile phone manufacturer, and the first phone call was made through it in the early seventies, then Motorola followed many other manufacturers, such as Sony Ericsson, LG, Panasonic and others, such as the camera was identified as part of a cell phone in 1997 AD by Philip Khan, and in 2007 85% of cell phones made with a camera.
The main parts of a landline phone
Transmitter device: the transmitter contains a metal disc called (the phone drum) or barrier, and when a person talks on the phone, the sound waves reach the phone drum and make it vibrate, and when it vibrates, it presses the carbon pills behind the drum. An electric current is passed along the wires of the person you are talking to and the volume of the voice is said to cause the drum to vibrate faster, resulting in more pressure on the carbon grains and therefore an increase in the flow of electric current.
Receiver device: the receiver contains a metal disc also called a drum and vibrates due to its connection with two magnets, one of which is an ordinary magnet which helps hold the drum in place, and the second magnet is the electromagnet, which is a piece of iron around which a conductive wire is wrapped, and when an electric current is passed through the coils of the wires, this piece of iron becomes a magnet and the drum of the receiving telephone acts as a transmitter and allows no one to speak for listening to the other person’s conversation.