![]() Perhaps the earliest use of the word for a communications system was the telephon created by Johann Sigismund Gottfried Huth in 1796. In later decades, their analog cellular system evolved into digital networks with greater capability and lower cost.Ĭonvergence in communication services has provided a broad spectrum of capabilities in cell phones, including mobile computing, giving rise to the smartphone, the dominant type of telephone in the world today.īell placing the first New York to Chicago telephone call in 1892īefore the development of the electric telephone, the term telephone was applied to other inventions, and not all early researchers of the electrical device used the term. Hand-held mobile phones were introduced for personal service starting in 1973. For greater mobility, various radio systems were developed for transmission between mobile stations on ships and automobiles in the mid-20th century. These exchanges were soon connected together, eventually forming an automated, worldwide public switched telephone network. Being impractical beyond just a few customers, these systems were quickly replaced by manually operated centrally located switchboards. The first telephones were directly connected to each other from one customer's office or residence to another customer's location. Telephone calls are initiated most commonly with a keypad or dial, affixed to the telephone, to enter a telephone number, which is the address of the call recipient's telephone in the telecommunication system, but other methods existed in the early history of the telephone. Most telephones also contain an alerting feature, such as a ringer or a visual indicator, to announce an incoming telephone call. ![]() Telephones permit transmission in both directions simultaneously. The transmitter converts the sound waves to electrical signals which are sent through the telecommunication system to the receiving telephone, which converts the signals into audible sound in the receiver or sometimes a loudspeaker. The receiver and transmitter are usually built into a handset which is held up to the ear and mouth during conversation. The essential elements of a telephone are a microphone ( transmitter) to speak into and an earphone ( receiver) which reproduces the voice at a distant location. This instrument was further developed by many others, and became rapidly indispensable in business, government, and in households. In 1876, Alexander Graham Bell was the first to be granted a United States patent for a device that produced clearly intelligible replication of the human voice at a second device. A common short form of the term is phone, which came into use early in the telephone's history. The term is derived from Greek: τῆλε ( tēle, far) and φωνή ( phōnē, voice), together meaning distant voice. A telephone converts sound, typically and most efficiently the human voice, into electronic signals that are transmitted via cables and other communication channels to another telephone which reproduces the sound to the receiving user. Today HK is still making high end equipment and computer / auto audio components.AT&T push button telephone made by Western Electric, model 2500 DMG black, 1980Ī telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be easily heard directly. The 330 and 330A were all transistor, but in the mid 1970's 330B incorporated one integrated circuit, a Motorola IF amplifier unit. The HK 330 series was an entry level receiver (20 watts/channel) and Harman Kardon was always you get what you paid for company so extras were few in number yet quality was maintained. The model you see below was a high school dream when I got interested in electronics. In early 1960's Fisher Radio would incorporate true multiplex stereo which we have today. In Los Angeles there was a classical music station was KFAC and they were in am and fm broadcasting the same material for this simulcast stereo. ![]() From the latre 1950's until the end of the 1960's many station would be am and fm for simulcast stereo. Harman Kardon first implemented simulcast stereo by having separate am and fm tuning sections so you can hear the am on one channel and fm on the other channel. ![]() ![]() Harman Kardon began during the late 1950's at the beginning of high fidelity tube am/fm equipment. Harman Kardon (HK) 330 series stereo receivers. Not really a transistor radio but one of the last all transistor receivers. ![]()
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