electricity

Alternating Current



Induction Coil / Transformer

In the 1880s every system for distributing electricity used direct current (DC). But DC transmission over long distances was impractical. Transmitting at low voltage required thick wires. Transmitting at high voltage was dangerous and could not be reduced for consumer uses such as lighting. It was known that alternating current (AC) voltage could be varied by use of induction coils, but no practical coil system had been invented.

Stanley's design for such a coil-or 'transformer' as it is now called-became the prototype for all future transformers.







System of Distribution by Alternating Currents


Charles Proteus Steinmetz
Born Apr 9 1865 - Died Oct 26 1923

System of Distribution by Alternating Currents
Alternating Current
Patent Number(s) 533,244

Inducted 1977


In 1893, Steinmetz joined the newly organized General Electric Company in Schenectady, New York, serving as consulting engineer until his death.

Steinmetz's first important research was on the phenomenon of hysteresis, by which power is lost because of magnetic resistance. This research led him directly to a study of alternating current, which could eliminate hysteresis loss in motors. The difficulty was that there was really no theory of alternating current by which the electrical engineer could be guided. Steinmetz set out to remedy this deficiency. During the next 20 years he prepared a series of masterful papers and volumes which reduced the theory of alternating current to order.

Steinmetz's last research was on lightning, which threatened to disrupt the new AC power lines. Here again he made fundamental contributions.


Without Charles Steinmetz's development of theories of alternating current, the expansion of the electric power industry in the United States in the early 20th century would have been impossible, or at least greatly delayed.






Electro-Magnetic Motor

Nikola Tesla invented the induction motor with rotating magnetic field that made unit drives for machines feasible and made AC power transmission an economic necessity.

In 1887 and 1888 Tesla had an experimental shop at 89 Liberty Street, New York, and there he invented the induction motor. He sold the invention to Westinghouse in July 1888 and spent a year in Pittsburgh instructing Westinghouse engineers.






Improvement in Steam-Power Brake Devices

George Westinghouse invented a system of air brakes that made travel by train safe and built one of the greatest electric manufacturing organizations in the United States.

After briefly attending Union College he returned to his father's shop, where he developed and patented a rotary steam engine, a device for replacing derailed freight cars, and a railroad frog.

He then worked to develop a system of railroad brakes that would centralize control in the hands of the engineer. He was awarded the first of many air brake patents in 1869 and at the age of 22 organized the Westinghouse Air Brake Company.
















Electric Lamp

One of the outstanding geniuses in the history of technology, Thomas Edison earned patents for more than a thousand inventions, including the incandescent electric lamp, the phonograph, the carbon telephone transmitter, and the motion-picture projector. In addition, he created the world's first industrial research laboratory. In September 1878, after having viewed an exhibition of a series of eight glaring 500-candlepower arc lights, Edison boldly announced he would invent a safe, mild, and inexpensive electric light that would replace the gaslight in millions of homes; moreover, he would accomplish this by an entirely different method of current distribution from that used for arc lights. To back the lamp effort, some of New York's leading financial figures joined with Edison in October 1878 to form the Edison Electric Light Company, the predecessor of today's General Electric Company. On October 21,1879, Edison demonstrated the carbon-filament lamp, supplied with current by his special high-voltage dynamos. The pilot light-and-power station at Menlo Park glowed with a circuit of 30 lamps, each of which could be turned on or off without affecting the rest. Three years later, the Pearl Street central power station in downtown New York City was completed, initiating the electrical illumination of the cities of the world. In 1887 Edison moved his workshop from Menlo Park to West Orange, New Jersey, where he built the Edison Laboratory (now a national monument), a facility 10 times larger than the earlier one. In time it was surrounded with factories employing some 5,000 persons and producing a variety of new products, among them his improved phonograph using wax records, the mimeograph, fluoroscope, alkaline storage battery, dictating machine, and motion-picture cameras and projectors. During World War I, the aged inventor headed the Naval Consulting Board and directed research in torpedo mechanisms and antisubmarine devices. It was largely owing to his urging that Congress established the Naval Research Laboratory, the first institution for military research, in 1920.

Throughout his career, Edison consciously directed his studies to devices that could satisfy real needs and come into popular use. Indeed, it may be said that in applying himself to technology, he was fulfilling the ideals of democracy, for he centered his attention upon projects that would increase the convenience and pleasure of mankind.





Incandescent Electric Lamp

Irving Langmuir's work led to two major inventions: the high-vacuum electron tube and the gas-filled incandescent lamp.













Fluorescent Lamp

Germer received the Frank P. Brown Medal from the Franklin Institute in 1954 for his fluorescent lamp.

Edmund Germer's development of the fluorescent lamp and the high-pressure mercury-vapor lamp significantly increased the efficiency of lighting devices, allowing for more economical lighting while producing less heat than incandescent light.











Laser


Optically Pumped Laser Amplifiers; Light Amplifiers Employing Collisions to Produce a Population Inversion


Gordon Gould coined the word laser and patented optically pumped and discharge excited laser amplifiers now used in most industrial, commercial, and medical applications of lasers.


Gould and his assignee, Patlex Corporation, now hold the basic patents covering optically pumped and discharge excited laser amplifiers. These lasers are used in 80 percent of the industrial, commercial, and medical applications of lasers. Gould also holds patents on laser uses and fiber optic communications.





Ruby Laser Systems

Physicist Theodore Harold Maiman invented the first operable laser.

While employed at Hughes Research Laboratories as a section head in 1960, he developed, demonstrated, and patented a laser using a pink ruby medium, for which he gained worldwide recognition.


The laser’s impact has rippled through numerous industries. Laser beams are being used in medicine, industry, electronic, data processing, communications, and scientific research in a myriad of ways. Doctors use them to remove tattoos and port wine stains (birthmarks), to repair detached retinas, and to perform bloodless surgery. Industry uses lasers to weld, drill, cut, seam, mark, and heat treat with the effect of high yield, excellent reproducibility, and higher throughput with consequence of improved productivity. Electronic firms use lasers to trim resistors and capacitors and to fashion and anneal transistor ‘chips’ to extremely high accuracy. Lasers are used in supermarket scanners to automate checkout; and now are used in the home in optical videodisc players. With the use of the laser, written and read-out, optical memory will increase storage capacity of computer information to 100 times the density of a magnetic disc or tape. Another innovation is the use of lasers to transmit light for miles without repeaters through hair-thin glass fibers to replace traditional wires in communication. Early on, laser beams were used to measure the 200,000 mile distance to the moon – within one inch. Many scientists predict lasers will play a significant role in harnessing the power of hydrogen ions – known as atomic fusion – in the future.





Masers and Maser Communications System


Arthur L. Schawlow was co-inventor of the laser. He worked with Charles H. Townes, who was inducted into the National Inventors Hall of Fame in 1976.

Schawlow and Townes were seeking ways to extend the maser principle of amplifying electromagnetic waves into the shorter wavelengths of infrared and visible light. They published a proposal for the laser in a 1958 issue of Physical Review and received a patent for it in 1960. By the end of the 1960s, eye surgeons were already routinely using lasers, taking advantage of the fact that they can be made minutely small and precisely focused. In 1961, Schawlow became professor of physics at Stanford University. It was in 1981 that Schawlow received the Nobel Prize in physics for his work in laser spectroscopy.

Today, the laser is prevalent in many areas, including the medical, defense and communications fields.





Production of Electromagnetic Energy; Masers and Maser Communications System

Charles Townes' invention of the maser, a device that amplifies electromagnetic waves, created a means for the sensitive reception of communications and for precise navigation. The maser provided basic components of the laser, for which Townes also received a patent.

The difference between a maser and a laser is that the laser utilizes visible light.

Apart from being useful tools in the laboratory, both masers and lasers have found many applications in radar, communications, astronomy, navigation, atomic clocks, surgery, and industry.











Magnetron

Asymmetrically Conductive Device and Method of Making the Same

Robert Hall invented the version of the magnetron that operates most microwave ovens, the semiconductor laser found in compact disk players, and power rectifiers that greatly improved power transmission efficiency.

His basic rectifier structure, with silicon replacing the germanium, is used today for AC-to-DC power conversion in electric locomotives and high-voltage DC electrical transmission. In 1962 Hall invented the semiconductor injection laser, a device now used in all compact disk players and laser printers, and most optical fiber communications systems.





High Efficiency Magnetron

Percy Spencer, while working for the Raytheon Company, discovered a more efficient way to manufacture magnetrons. In 1941, magnetrons were being produced at a rate of 17 per day. Spencer set out to create a simpler magnetron that could be mass produced. The result was a magnetron that replaced precision copper bars with lamina and replaced soldered internal wires with a simple solid ring. These improvements and others allowed for the faster production of 2,600 magnetrons per day.

In 1945, Spencer created a device to cook food using microwave radiation. Raytheon saw the possibilities of this, and after acquiring Amana Refrigeration in 1965, was able to sell microwave ovens on a large scale. The first microwave oven was called the Radarange, and today, there are over 200 million in use throughout the world.


This discovery led to significant advances in radar and his most popular invention, the microwave oven.