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Step-by-step Switch
The Strowger switch is the first commercially successful electromechanical stepping switch telephone exchange system. It was developed by the Strowger Automatic Telephone Exchange Company founded in 1891 by Almon Brown Strowger. Based on its mechanical characteristics, it is also known as a step-by-step (SXS) switch. History Strowger, an undertaker, was motivated to invent an automatic telephone exchange after becoming convinced that the manual telephone exchange operators were deliberately interfering with his calls, leading to loss of business. According to the local Bell Telephone Company manager Herman Ritterhoff, Strowger swore to "get even" with the telephone operators and "put every last one of them out of a job." Ritterhoff claimed in 1913 that the real cause of Strowger's difficulties was a metal sign hung on his wall over his telephone, causing an intermittent short circuit when blown by the wind. Strowger conceived his invention in 1888, and was awarded a pat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uniselector Stepper Detail
In electrical engineering, a stepping switch or stepping relay, also known as a uniselector, is an Electromechanics, electromechanical device that Switch, switches an input signal path to one of several possible output paths, directed by a train of electrical pulses. The major use of stepping switches was in early automatic telephone exchanges to route telephone calls. Later, they were often used in industrial control systems. During World War II, Japanese cypher machines, known in the United States as Coral (cypher machine), CORAL, JADE (cypher machine), JADE, and Purple (cipher machine), PURPLE, contained them. Code breakers at Bletchley Park employed uniselectors driven by a continuously rotating motor rather than a series of pulses in the Colossus to cryptanalyse the German Lorenz ciphers. In a uniselector, the stepping switch steps only along or around one axis, although several sets of contacts are often operated simultaneously. In other types, such as the Strowger switch, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Strowger Switch Milton Keynes Museum
Strowger may refer to: * Strowger switch, automatic telephone exchange equipment * Strowger Automatic Telephone Exchange Company, the company that manufactured Strowger switches * Almon Brown Strowger Almon Brown Strowger (; February 11, 1839 – May 26, 1902) was an American inventor for whom the Strowger switch, an electromechanical telephone exchange technology, is named. Early years Strowger was born in Penfield, New York, near Roches ... (1839–1902), who invented the principle of the Strowger switch in 1888 See also * Stroger (other) {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uniselector
In electrical engineering, a stepping switch or stepping relay, also known as a uniselector, is an electromechanical device that switches an input signal path to one of several possible output paths, directed by a train of electrical pulses. The major use of stepping switches was in early automatic telephone exchanges to route telephone calls. Later, they were often used in industrial control systems. During World War II, Japanese cypher machines, known in the United States as CORAL, JADE, and PURPLE, contained them. Code breakers at Bletchley Park employed uniselectors driven by a continuously rotating motor rather than a series of pulses in the Colossus to cryptanalyse the German Lorenz ciphers. In a uniselector, the stepping switch steps only along or around one axis, although several sets of contacts are often operated simultaneously. In other types, such as the Strowger switch, invented by Almon Brown Strowger in 1888, mechanical switching occurs in two directions, across ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Busy Signal
A busy signal (or busy tone or engaged tone) in telephony is an audible call-progress tone or audible signal to the calling party that indicates failure to complete the requested connection of that particular telephone call. The busy signal has become less common in the past few decades due to the prevalence of call waiting and voicemail. Reasons for a busy signal An otherwise unspecified busy signal indicates that the called number is occupied: * The called number is talking with another caller on the phone * The number is calling out * Someone else has called the number or is calling the number at the same time * The other line was left off-hook * It is otherwise unavailable The standard busy signal sometimes occurs (sometimes with an intercept message played over the busy) at the end of a call to indicate the other party has hung up (see Disconnect tone), but mostly the off-hook tone is used. In some phone companies in the United Kingdom, the busy signal is played af ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ratchet (device)
A ratchet (occasionally spelled rachet) is a mechanical device that allows continuous linear or rotary motion in only one direction while preventing motion in the opposite direction. Ratchets are widely used in machinery and tools. The word ''ratchet'' is also used informally to refer to a ratcheting socket wrench. __TOC__ Theory of operation A ratchet consists of a round gear or a linear rack with teeth, and a pivoting, spring-loaded finger called a '' pawl'' (or ''click'', in clocks and watches) that engages the teeth. The teeth are uniform but are usually asymmetrical, with each tooth having a moderate slope on one edge and a much steeper slope on the other edge. When the teeth are moving in the unrestricted (i.e. forward) direction, the pawl easily slides up and over the gently sloped edges of the teeth, with a spring forcing it (often with an audible 'click') into the depression between the teeth as it passes the tip of each tooth. When the teeth move in the oppo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rotary Dial
A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing. It is used when initiating a telephone call to transmit the destination telephone number to a telephone exchange as a succession of individual digits. On the rotary dial, the digits are arranged in a circular layout, with one finger hole in the finger wheel for each digit. For dialing a digit, the wheel is rotated against spring tension with one finger positioned in the corresponding hole, pulling the wheel with the finger to a stop position given by a mechanical barrier, the finger stop. When released at the finger stop, the wheel returns to its home position driven by the spring at a speed regulated by a governor device. During this return rotation, an electrical switch interrupts the direct current (DC) of the telephone line (local loop) the specific number of times associated with each digit and thereby generates elect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Knife Switch
A knife switch is a type of switch used to control the flow of electricity in a electrical circuit, circuit. It is composed of a hinge which allows a metal lever, or ''knife'', to be lifted from or inserted into a Groove (engineering), slot or jaw. The hinge and jaw are both fixed to an Electrical insulation, insulated base, and the knife has an insulated handle. Current flows through the switch when the knife is pushed into the jaw. Knife switches can take several forms, including ''single-throw'', in which the knife engages with only a single slot, and ''Switch#Contact_arrangements, double-throw'', in which the knife hinge is placed between two slots and can engage with either one. Multiple knives may be attached to a single handle and can be used to activate more than one circuit simultaneously; this is a ''multi-pole'' switch. Current uses Though used commonly in the past, knife switches are now rare, finding use largely in science demonstrations where the exposed mechanic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pulse (signal Processing)
A pulse in signal processing is a rapid, transient change in the amplitude of a signal from a baseline value to a higher or lower value, followed by a rapid return to the baseline value. Pulse shapes Pulse shapes can arise out of a process called pulse shaping. Optimum pulse shape depends on the application. Rectangular pulse These can be found in pulse waves, square waves, boxcar functions, and rectangular functions. In digital signals the up and down transitions between high and low levels are called the rising edge and the falling edge. In digital systems the detection of these sides or action taken in response is termed edge-triggered, rising or falling depending on which side of rectangular pulse. A digital timing diagram is an example of a well-ordered collection of rectangular pulses. Nyquist pulse A Nyquist pulse is one which meets the Nyquist ISI criterion In communications, the Nyquist ISI criterion describes the conditions which, when satisfied by a comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catford Strowger Switch
Catford is a district in south east London, England, and the administrative centre of the London Borough of Lewisham. It is southwest of Lewisham itself, mostly in the Rushey Green and Catford South wards. The population of Catford, including Bellingham, was 44,905 in 2011. Catford covers most of SE6 postcode district. The area is identified in the London Plan as one of 35 major centres in Greater London. History Toponymy The origin of the name is unknown. Speculation suggests it may derive from the place where cattle crossed the river Ravensbourne in Anglo-Saxon times or from wild cats using the river crossing. Governance Catford is covered by the Rushey Green and Catford South wards in the London Borough of Lewisham. It also makes up a large part of the Lewisham East constituency. Built environment Early developments Broadway Theatre is an art deco building adjoining the town hall. It is a curved stone structure decorated with shields and heraldic emblems and t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Director Telephone System
The director telephone system was a development of the Strowger or step-by-step (SXS) switching system used in London and five other large cities in the UK from the 1920s to the 1980s. A large proportion (c. 70% to 80%) of telephone traffic in large metropolitan areas is outgoing traffic, and it is distributed over many exchanges. A non-director SXS exchange system is not suitable for these areas. As the translation facility incorporated was similar to the register in common control systems, the director system incorporates two features of the Panel system, which was introduced in large American cities, and which were required regardless of the type of exchange system for these large areas, which would have a mixture of manual and automatic exchanges for some years. Customer stations were assigned seven-digit numbers, with the first three digits spelling out the local exchange name; this expedited call handling particularly to and from manual exchanges. Direct or tandem juncti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
