UNIVERSITATEA TRANSILVANIA DIN BRASOV The telephone A revolution in communication Student: Teris Alexandra IEC 4521 Coordinating teacher: Prof. Dr. Ing. Helerea Elena Teris Alexandra IEC 4521 May 2013 Table of Contents 1. Introduction ..........................................................................................................3 2. Description and operating principle ..................................................................3 3. History of the device .......................................................................................4 3.1 Evolution of the device ...............................................................................5 3.2 The telephone in Romania ........................................................................6 4. Impact on the society ......................................................................................7 5. Conclusions .....................................................................................................7 6. Bibliography .....................................................................................................7 7. Iconography .....................................................................................................7 2 Teris Alexandra IEC 4521 1. Introduction In our days we run along an “information superhighway” with sophisticated utensils which are far away of the first telephone. Such communication devices like computers, mobile telephones, pagers, caller ID, call waiting, numbers like 112, are now taken for granted. Modern electronic devices are continuously changing, continuously evolving, making the old plug and jack switchboards look like they belong to the Stone Age. We accept all of these things and we are even capable to accept Alexander Graham Bell as the inventor of the Telephone [1]. 2. Description and operating principle The simplest functional telephone should be constructed in the following way inside. It only contains three simple parts: - a switch for connecting and disconnecting the telephone from the system, this switch is usually named a hook switch. It connects when you lift the handset. - a speaker - is generally a little 50-cent, 8-ohm speaker of some sort. - a microphone - in the past, telephone microphones have been as simple as carbon granules compressed between two thin metal plates. Sound waves from your voice compress and decompress the granules, changing the resistance of the granules and modulating the current flowing through the microphone (Fig. 1)[2]. Fig. 1 The components of the telephone One can dial this simple phone by rapidly tapping the hook switch - all telephone switches still recognize "pulse dialing." If you pick the phone up and rapidly tap the switch hook four times, the phone company's switch will understand that you have dialed a "4." A "real" telephone Most people find that annoying, so any "real" phone contains a device called a duplex coil or something functionally equivalent to block the sound of your own voice from reaching your ear. 3 Teris Alexandra IEC 4521 A modern telephone also includes a bell so it can ring and a touch-tone keypad and frequency generator. A "real" phone looks like this (Fig.2)[3]. Fig.2 A more modern telephone Still the more modern telephone is pretty simple. In this kind of a device there is an electronic microphone, amplifier and circuit to replace the carbon granules and loading coil. The mechanical bell is often replaced by a speaker and a circuit to generate a pleasant ringing tone[3]. 3. History of the device On March 10, 1876, in Boston, Massachusetts, Alexander Graham Bell invented the telephone. (Fig.3) Fig.3 Graham Bell’s Transmitter and Receiver Thomas Watson made the design of the device itself; an object made of a wooden stand, a funnel, a cup of acid and some copper wires. But these simple elements were the ones which led to the simple first phone call: “Mr. Watson, come here, I want you!” [4]. 4 Teris Alexandra IEC 4521 An interesting fact is that Bell filed thee application with just a few hours before his competitor Elisha Gray filed an application to patent a telephone himself. In spite of these facts, it wasn’t easy for the weak young telephone to make itself heard in the noisy workshop. Not even Bell and Watson were not used to the weird voice that was heard through the handset. Usually, it was Watson which had a very good sense of hearing would have done the listening and Bell would have done the talking. In time, the tone of the little device became more clearly. At Bell’s 29’th anniversary he received the patent No. 174465 “the most valuable simple patent ever issued” in any country. He had created something so new that there wasn’t even a name for it in no other language. Even Bell, describing the device to the Officials of the Patent Office, was obliged to name it “an improvement in telegraphy” when in fact was nothing alike. The story of the telephone is actually the story of its invention. Bell managed to create the device because he understood acoustics, he understood sound and studied a little bit about electricity. The discovery of the telephone was not easy and it was the result of a persistent search [5]. 3.1 Evolution of the device • 1844 — Innocenzo Manzetti first mooted the idea of a “speaking telegraph” or telephone. Use of the 'speaking telegraph' and 'sound telegraph' monikers would eventually be replaced by the newer, distinct name, 'telephone'. • 26 August 1854 — Charles Bourseul published an article in the magazine L'Illustration (Paris): "Transmission électrique de la parole" (electric transmission of speech), describing a 'make-and-break' type telephone transmitter later created by Johann Reis. • 26 October 1861 — Johann Philipp Reis (1834–1874) publicly demonstrated the Reis telephone before the Physical Society of Frankfurt. • 22 August 1865, La Feuille d'Aoste reported “It is rumored that English technicians to whom Mr. Manzetti illustrated his method for transmitting spoken words on the telegraph wire intend to apply said invention in England on several private telegraph lines". However telephones would not be demonstrated there until 1876, with a set of telephones from Bell. • 28 December 1871 — Antonio Meucci files patent caveat No. 3335 in the U.S. Patent Office titled "Sound Telegraph", describing communication of voice between two people by wire. A 'patent caveat' was not an invention patent award, but only an unverified notice filed by an individual that he or she intends to file a regular patent application in the future. • 1874 — Meucci, after having renewed the caveat for two years does not renew it again, and the caveat lapses. • 6 April 1875 — Bell's U.S. Patent 161,739 "Transmitters and Receivers for Electric Telegraphs" is granted. This uses multiple vibrating steel reeds in make-break circuits. • 11 February 1876 — Gray invents a liquid transmitter for use with a telephone but does not build one. • 14 February 1876 — Elisha Gray files a patent caveat for transmitting the human voice through a telegraphic circuit. 5 Teris Alexandra IEC 4521 • 14 February 1876 — Alexander Bell applies for the patent "Improvements in Telegraphy", for electromagnetic telephones using what is now called amplitude modulation (oscillating current and voltage) but which he referred to as "undulating current". • 19 February 1876 — Gray is notified by the U.S. Patent Office of an interference between his caveat and Bell's patent application. Gray decides to abandon his caveat. • 7 March 1876 — Bell's U.S. patent 174,465 "Improvement in Telegraphy" is granted, covering "the method of, and apparatus for, transmitting vocal or other sounds telegraphically … by causing electrical undulations, similar in form to the vibrations of the air accompanying the said vocal or other sound." • 10 March 1876 — The first successful telephone transmission of clear speech using a liquid transmitter when Bell spoke into his device, “Mr. Watson, come here, I want to see you.” and Watson heard each word distinctly. • 30 January 1877 — Bell's U.S. patent 186,787 is granted for an electromagnetic telephone using permanent magnets, iron diaphragms, and a call bell. • 27 April 1877 — Edison files for a patent on a carbon (graphite) transmitter. The patent 474,230 was granted 3 May 1892, after a 15 year delay because of litigation. Edison was granted patent 222,390 for a carbon granules transmitter in 1879 [6]. • 20 February 1984 — The telephone became portable, when the American Donald M. Mitchell requested the release of a patent for his cell phone: “Portable radio for transmission and reception”. The device transmitted using short waves, had a limited range and weighed 2.5 Kg. There have passed 35 more years until cell phones began to be widely used by ordinary people [7]. Fig. 4 Motorola DynaTAC 8000X, one of the first mobile phones that operates in analogue system 3.2 The telephone in Romania 6 Teris Alexandra IEC 4521 • 1882 – Appeared the first telephone in Romania, in Bucharest and they were Siemens telephones. • 1884 – In Bucharest took place the first telephonic communication. • 1889 – In Bucharest was installed the first station with 5 receivers; the line was installed between the parliament and the main ministers. • 1890 – Private telephones began to be installed and until 1893 there were about 300 telephonic receivers • 1906 – Augustin Maior manages to transmit simultaneously, on a single telephone line of 15 km, 5 calls without their signals interfering [8]. 4. Impact on the society The telephone is an all purpose