Museum
Location: Administrative Building, RCOEM, Nagpur.
The objective of the museum is to make the old technologies engineering instruments available for students and public viewing purpose through exhibits. Some of the attractions in the museum are Gramophone, Valve Amplifier & Radio, Recorder players, Old handsets of Telephones, Old Cameras, A Sextant (which was primarily used for navigation purpose and has been invented firstly in 18th century), Overhead projector, CRT TV set etc.
Valve Amplifier
A valve/ tube amplifier is an electronic amplifier that uses vacuum tubes to increase the amplitude or power of a signal. Low to medium power valve amplifiers for frequencies below the microwaves were largely replaced by solid state amplifiers in the 1960s and 1970s.Until the invention of the transistor in 1947, most practical high-frequency electronic amplifiers were made using thermionic valves. The simplest valve (named as a diode because of two electrodes) was invented by John Ambrose Fleming while working for the Marconi Company in London in 1904. In 1906 Lee De Forest added a third electrode and invented the first electronic amplifying device, the triode, which he named the Audion. The first application of valve amplification was in the regeneration of long distance telephony signals. Later, valve amplification was applied to the ‘wireless’ market that began in the early 30’s. In due course amplifiers for music and later television were also built using valves.
The Telephone
A telephone is a telecommunications device that permits two or more users to conduct a conversation when they are too far apart to be heard directly.The term “telephone” is derived from Greek: τῆλε (tēle, far) and φωνή (phōnē, voice), together meaning distant voice. In 1870s, two inventors Elisha Gray and Alexander Graham Bell both independently designed devices that could transmit speech electrically (the telephone). Both men rushed their respective designs to the patent office within hours of each other. Alexander Graham Bell patented his telephone first. Elisha Gray and Alexander Graham Bell entered into a famous legal battle over the invention of the telephone, which Bell won.
Overhead Projector
The overhead projector: An overhead projector (OHP), like a film or slide projector, uses light to project an enlarged image on a screen, allowing the view of a small document or picture to be shared with a large audience. In the overhead projector, the source of the image is a page-sized sheet of transparent plastic film (also known as “foils” or “transparencies”) with the image to be projected either printed or hand-written/drawn. These are placed on the glass platen of the projector, which has a light source below it and a projecting mirror and lens assembly above it (hence, “overhead”). They were widely used in education and business before the advent of video projectors.French physicist Edmond Becquerel developed the first known overhead projection apparatus in 1853. It was demonstrated by French instrument maker and inventor Jules Duboscq in 1866.
Videocassette recorder
A videocassette recorder (VCR) or video recorder is an electromechanical device that records analog audio and video from broadcast television or other source on a removable, magnetic tape videocassette, and can play back the recording. Use of a VCR to record a television program to play back at a more convenient time is commonly referred to as timeshifting. VCRs can also play back prerecorded tapes. In the 1980s and 1990s, prerecorded videotapes were widely available for purchase and rental, and blank tapes were sold to make recordings. The history of the videocassette recorder follows the history of videotape recording in general.In 1953, Dr. Norikazu Sawazaki developed a prototype helical scan video tape recorder. In 1970, Philips developed a home video cassette format specially made for a TV station in 1970 and available on the consumer market in 1972. Philips named this format “Video Cassette Recording”. In 1972, videocassettes of movies became available for home use.
Audio cassette player/recorder
An audio cassette recorder, also known as a tape deck/ tape player/tape machine or simply a tape recorder, is a sound recording and reproduction device that records and plays back sounds usually using magnetic tape for storage. In its present-day form, it records a fluctuating signal by moving the tape across a tape head that polarizes the magnetic domains in the tape in proportion to the audio signal. Tape-recording devices include the reel-to-reel tape deck & the cassette deck, which uses a cassette for storage. The use of magnetic tape for sound recording originated around 1930 in Germany as paper tape with oxide lacquered to it. Prior to the development of magnetic tape, magnetic wire recorders had successfully demonstrated the concept of magnetic recording, but they never offered audio quality comparable to the other recording and broadcast standards of the time. This German invention was the start of a long string of innovations that have led to present-day magnetic tape recordings.Magnetic tape revolutionized both the radio broadcast and music recording industries. It was recording and re-recording audio with minimal loss in quality as well as edit and rearrange recordings with ease. As of the first decade of the 21st century, analog magnetic tape has been largely replaced by digital rec. technologies.
Radio Set
In radio communications, a radio receiver, also known as a receiver, a wireless or simply a radio, is an electronic device that receives radio waves and converts the information carried by them to a usable form. The first radio receivers were only able to receive Morse code and even though the first radio broadcasts took place in 1906. Radio sets were implemented using vacuum tubes in early years. The first radio receivers invented by Guglielmo Marconi, Oliver Lodge and Alexander Popov in 1894-95 used a primitive radio wave detector called a coherer, invented in 1890 by Edouard Branly and improved by Lodge and Marconi. The coherer was a glass tube with metal electrodes at each end, with loose metal powder between the electrodes. It initially had a high resistance.When a radio frequency voltage was applied to the electrodes, its resistance dropped and it conducted electricity. In the receiver the coherer was connected directly between the antenna and ground. During initial years, most radio sets were homemade, so the use by the public was restricted. With the invention of the transistor in 1947 by the Bell Laboratories, it then became possible to produce small portable radios.
TV Set
John Logie Baird was a Scottish inventor, electrical engineer, and innovator who demonstrated his working television in 1926. In his first attempts to develop a working television system, Baird experimented with the Nipkow disc. Paul Gottlieb Nipkow had invented this scanning disc system in 1884. Television historian Albert Abramson calls Nipkow’s patent “the master television patent”. Nipkow’s work is important because Baird and many others chose to develop it into a broadcast medium. In 1928 the Baird Television Development Company achieved the first transatlantic television transmission. TV is introduced in the late 1920s in mechanical form, television sets became a popular consumer product after World War II in electronic form, using cathode ray tube (CRT) technology. By the early 2010s, flat-panel television incorporating liquid-crystal display (LCD) technology, LED-backlit LCD technology largely replaced CRT and other display technologies.
Rheostat & Dimmerstat
Dimmerstat is a continuously variable voltage auto- transformer. It is the most useful and effective device for stepless, breakless and continues control of a.c. voltage. It is an ideal controlling device for numerous applications in laboratories and in industrial & commercial fields. The basic dimmerstat is meant for operation of a nominal voltage of 240V a.c. and can give output voltage anywhere between 0 to 240V or up to 270V by a simple transformer action. Dimmertats are used for light control in auditoriums, hotels, restaurants, theatre stages, photo studious, verandahs, lobbies, conference halls, cinema houses and even in homes. In 1959, Joel S. Spira, invented a dimmer based on a diode and a tapped autotransformer, saving energy and allowing the dimmer to be installed in a standard electrical wallbox. The most common way to vary the resistance in a circuit continuously is to use a rheostat. It is basically used to adjust magnitude of current in a circuit by changing length.The word rheostat was coined about 1845 by Sir Charles Wheatstone, from the Greek ῥέος rheos meaning “stream”, and -στάτης -states (from ἱστάναι histanai, ” to set, to cause to stand”) meaning “setter, regulating device”, which is a two-terminal variable resistor. The term “rheostat” is becoming obsolete, with the general term “potentiometer” replacing it. For low-power applications (<1 watt) a three-terminal potentiometer is often used, with one terminal unconnected or connected to the wiper. Where the rheostat must be rated for higher power (>1 watt), it may be built with a resistance wire wound around a semicircular insulator, with the wiper sliding from one turn of the wire to the next. Sometimes a rheostat is made from resistance wire wound on a heat-resisting cylinder, with the slider made from a number of metal fingers that grip lightly onto a small portion of the turns of resistance wire.
E P Level Instrument
To determine the elevation difference between two or more than two objects / stations, leveling instrument is required. Leveling operation helps us to know the gradient between the various objects. This information is essential in designing the alignments for road, rail-road, water supply line, sewer line and storm water lines, etc on the field. Leveling instrument is also useful in deciding and maintaining different levels during the construction activity.
Cathode Ray Oscilloscope with Function Generator & Frequency Counter
AC/DC Voltage/ Current measuring instrument- Analog type
The gramophone
A phonograph, in its later forms also called a gramophone (as a trademark since 1887, as a generic name in the UK since 1910) or since the 1940s called a record player, is a device for the mechanical recording and reproduction of sound. The sound vibration waveforms are recorded as corresponding physical deviations of a spiral groove engraved, etched, incised, or impressed into the surface of a rotating cylinder or disc, called a “record”. To recreate the sound, the surface is similarly rotated while a playback stylus traces the groove and is therefore vibrated by it, very faintly reproducing the recorded sound. The phonograph was invented in 1877 by Thomas Edison. Alexander Graham Bell’s Volta Laboratory made several improvements in the 1880s and introduced the gramophone, including the use of wax-coated cardboard cylinders and a cutting stylus that moved from side to side in a zigzag groove around the record.
The Sextant
A sextant is a doubly reflecting navigation instrument that measures the angular distance between two visible objects. The primary use of a sextant is to measure the angle between an astronomical object and the horizon for the purposes of celestial navigation. The estimation of this angle, the altitude, is known as sighting or shooting the object, or taking a sight. The angle, and the time when it was measured, can be used to calculate a position line on a nautical/aeronautical chart for example, sighting the Sun at noon or Polaris at night (in the Northern Hemisphere) to estimate latitude. Sighting the height of a landmark can give a measure of distance off and, held horizontally; a sextant can measure angles between objects for a position on a chart. A sextant can also be used to measure the lunar distance between the moon and another celestial object (such as a star or planet) in order to determine Greenwich Mean Time and hence longitude. The principle of the instrument was first implemented around 1731 by John Hadley (1682–1744) and Thomas Godfrey (1704–1749), but it was also found later in the unpublished writings of Isaac Newton (1643–1727). In 1922, it was modified for aeronautical navigation by Portuguese navigator and naval officer Gago Coutinho.
The Camera
A camera is an optical instrument that captures a visual image. Cameras are sealed boxes (the body) with a small hole (the aperture) that allows light in to capture an image on a light-sensitive surface (usually photographic film or a digital sensor). Cameras have various mechanisms to control how the light falls onto the light-sensitive surface. Lenses focus the light entering the camera, the size of the aperture can be widened or narrowed to let more or less light into the camera, and a shutter mechanism determines the amount of time the photo-sensitive surface is exposed to the light. The still image camera is the main instrument in the art of photography and captured images may be reproduced later as a part of the process of photography, digital imaging, photographic printing. The similar artistic fields in the moving image camera domain are film, videography, and cinematography. The word “camera” comes from camera obscura, which means “dark chamber” and is the Latin name of the original device for projecting an image of external reality onto a flat surface. The modern photographic camera evolved from the camera obscura. The functioning of the camera is very similar to the functioning of the human eye. The first permanent photograph was made in 1825 by Joseph Nicéphore Niépce.
