Telegraph relays amplified electrical signals in a telegraph line. Telegraph messages traveled as a series of electrical pulses through a wire from a transmitter to a receiver. Short pulses made a dot, slightly longer pulses a dash. The pulses faded in strength as they traveled through the wire, to the point where the incoming signal was too weak to directly operate a receiving sounder or register. A relay detected a weak signal and used a battery to strengthen the signal so that the receiver would operate.
This relay includes a marble base and was made by Charles T. Chester of New York City. The electromagnet coils are fixed but the steel core can be moved to adjust the strength of the magnetic field.
The cables needed to transmit electrical power may seem simple but are actually complex technological artifacts. Modern cables inherit the lessons learned during more than a century of research and experience. This power cable was described by GE engineer William Clark in 1898 as follows: “1,000,000 [circular mil] cable composed of 59 wires, each .1305" in diameter, containing two insulated pressure wires each 2500 C.M. area, the whole insulated with saturated paper 5/32" thick and finished with lead 1/8" thick. This is a feeder cable for circuits not exceeding 2000 volts working pressure on Edison three wire circuits."
Early radio inventors used a variety of methods to detect radio waves. Those early detectors tended to be slow and cumbersome in operation and that limited transmission speed. In 1906, Lee de Forest built on the work of Thomas Edison and John Ambrose Fleming and invented an electron tube he called an “Audion.” His tube contained three internal elements: a filament, an electrode and a control grid. Today we call tubes of this type “triodes.” In 1907 De Forest received U.S. Patent #841,387 for his invention, one of the most important in the history of radio.
Dolby model A301 audio noise reduction unit, serial no. 2. Unit uses Dolby A-type noise reduction circuitry and was produced for professional recording studios and cinema sound production studios. This unit was used by Decca Records.
Invention rarely stops when the inventor introduces a new device. Thomas A. Edison and his team worked to improve his electric lighting system for some years after the initial introduction in 1880. This lamp shows changes made after about ten years of labor aimed at lowering costs and increasing production. The simplified base required little material; the diameter and thread-pitch are still used today. The filament was changed from bamboo to a treated cellulose, based on an invention by English chemist Joseph Swan. The bulb was probably free blown by Corning Glass Works, but would soon be replaced by a bulb made by semi-skilled laborers blowing glass into iron molds. The cost had dropped from about $1.00 per lamp to less than 30¢.
The cables needed to transmit electrical power may seem simple but are actually complex technological artifacts. Cables are designed for many different applications, for example, indoor or outdoor use. This power cable was described by GE engineer William Clark in 1898 as follows: “500,000 [circular mil] cable, 3/32" rubber insulation, braided. [This cable is] for general use in interior wiring."
In 1907 Ohio janitor turned inventor James Murray Spangler developed a new type of electrical sweeper for cleaning carpets. Unable to finance large-scale manufacture of his invention, he turned to a local harness and leather goods maker, William H. Hoover, who established the Electric Suction Sweeper Company. In November 1908, Spangler filed for a US patent and almost a year later received patent number 935,558 that he assigned to Hoover’s new company. This 1908 Hoover vacuum cleaner shows the features seen in the patent: a fan to produce the vacuum and push air into a dust bag, rings on the bottom of the unit to keep the carpet from being pulled into the fan, and brushes driven by the same motor as the fan.
Several inventors developed mechanical carpet cleaners during the 19th century and Spangler’s design was not the first attempt to adapt electricity to this task. One of the major innovations that made Hoover successful lay in how he sold the machine. Hoover realized the value of free, in-home trials and live demonstrations by trained sales-people. Innovations in both technology and marketing combined to make the product successful.
Description: Tin housing, restored silver-colored bag and new wooden handle. "Hoover" lettered on front. Markings: "Trade Hoover mark (/) Suction Sweeper (/) Co. (/) New Berlin". Alternating current motor 110 volt 66 cycle. Reference: US Patent 935558, issued 28 September 1909 to James Murray Spangler, assigned to the Electric Suction Sweeper Co., of New Berlin, OH - later the Hoover Vacuum Co. of New Canton, OH.
Made by Diamond Multimedia. Diamond Rio model PMP300 portable MP3 player. “Diamond” “Rio PMP300”. An early, commercially successful MP3 digital audio player.
This model 55 Shure microphone was used at the KCOR-AM radio building in San Antonio, Texas during the 1950s. First introduced in 1939, the microphone became iconic due to its adoption by radio personalities and musical acts. The microphone uses Shure’s “Unidyne” element, a pick-up element that only accepts sounds from one direction and forms a cardioid sensitivity pattern. KCOR was licensed and operated by Raoul A. Cortez (1905-1971), a pioneer of Spanish-language media in the United States. Cortez later established the KCOR-TV station in 1955, and programmed his stations to serve the Spanish-speaking community in Texas.
The Global Positioning System (GPS) consists of a network of orbiting satellites that transmit special time signals. GPS receivers detect the signals from several satellites and calculate the user’s position with high precision. While many civilian uses have been developed, the system originated as a tool for the U.S. military. Other nations also adopted GPS for military use as seen on this 1992 model 1000M5 receiver. The buttons are labeled in Arabic for use by the Egyptian Army.
Thomas Edison and others considered element number 6, carbon, ideal for lamp filaments in part because it has the highest melting point of any element. Element number 74, tungsten, has the next highest melting point but it then existed only as a powder. Attempts to make it into a workable form failed until early in the 1900s when a burst of invention occurred in Europe. A pressing technique called "sintering" (squeezing a material into a dense mass) was adopted by several inventors.
The most commercially successful design proved to be that of Dr. Alexander Just and Franz Hanaman of Austria. Their work on sintering tungsten was based on a prior sintering process developed by Carl Auer von Welsbach for his filament made of osmium. Just and Hanaman made a tungsten and organic paste, squirted it through a die, baked out the organic material, then sintered the tungsten in a mix of gasses. The resulting filament gave about 8 lumens per watt and lasted 800 hours.
Another Austrian, Dr. Hans Kutzel, used an electric arc to make a tungsten and water paste. He then pressed, baked, and sintered the tungsten in a manner similar to Just and Hanaman's procedure. Yet another pair of Austrians, Fritz Blau and Hermann Remane, adapted the osmium lamp process (they worked for Welsbach) by making a filament from an osmium and tungsten mix. They soon changed their "Osram" lamp filament to tungsten only. (The German word for tungsten is wolfram.)
All three filaments were brittle and collectively known as "non-ductile" filaments. Individual filaments could not be made long enough to give the proper electrical resistance, so lamps needed several filaments connected end-to-end. U.S. companies quickly licensed rights to all of the non-ductile patents. This particular lamp was made under license by General Electric and sent to the National Bureau of Standards for use as a standard lamp.
Lamp characteristics: Medium-screw base with glass insulator. Five single-arch tungsten filaments (in series) with 5 upper and 8 lower support hooks. The stem assembly features soldered connectors, Siemens-type press seal, and a cotton insulator. Tipped, straight-sided envelope with taper at neck.
Irving Langmuir received a Ph.D. in physical chemistry in 1906 from the University of Göttingen. He studied under Walther Nernst, who had invented a new type of incandescent lamp only a few years before. In 1909 Langmuir accepted a position at the General Electric Research Laboratory in Schenectady, New York. Ironically, he soon invented a lamp that made Nernst's lamp (and others) obsolete.
Langmuir experimented with the bendable tungsten wire developed by his colleague William Coolidge. He wanted to find a way to keep tungsten lamps from "blackening" or growing dim as the inside of the bulb became coated with tungsten evaporated from the filament. Though he did not solve this problem, he did create a coiled-tungsten filament mounted in a gas-filled lamp—a design still used today.
Up to that time all the air and other gasses were removed from lamps so the filaments could operate in a vacuum. Langmuir found that by putting nitrogen into a lamp, he could slow the evaporation of tungsten from the filament. He then found that thin filaments radiated heat faster than thick filaments, but the same thin filament–wound into a coil–radiated heat as if it were a solid rod the diameter of the coil. By 1913 Langmuir had gas–filled lamps that gave 12 to 20 lumens per watt (lpw), while Coolidge's vacuum lamps gave about 10 lpw.
During the 1910s GE began phasing-in Langmuir's third generation tungsten lamps, calling them "Mazda C" lamps. Although today's lamps are different in detail (for example, argon is used rather than nitrogen), the basic concept is still the same. The lamp seen here was sent to the National Bureau of Standards in the mid 1920s for use as a standard lamp.
Lamp characteristics: Brass medium-screw base with skirt and glass insulator. Two tungsten filaments (both are C9 configuration, mounted in parallel) with 6 support hooks and a support attaching each lead to the stem. The stem assembly includes welded connectors, angled-dumet leads, and a mica heat-shield attached to the leads above the press. The shield clips are welded to the press. Lamp is filled with nitrogen gas. Tipless, G-shaped envelope with neck.
New lighting inventions occasionally appear from unexpected directions. The development of this microwave-powered lamp provides a case in point. In 1990 Fusion Systems was a small company with a successful, highly specialized product, an innovative ultraviolet (UV) industrial lighting system powered by microwaves.
Discharge lamps typically use electrodes to support an electric arc. Tungsten electrodes are most common, so materials that might erode tungsten can't be used in the lamp and care must be taken to not melt the electrodes. Fusion's lamp side-stepped this problem by eliminating electrodes entirely. Microwave energy from an external source energized the lamp. This opened the way for experiments with non-traditional materials, including sulfur.
During the 1980s engineer Michael Ury, physicist Charles Wood, and their colleagues experimented several times with adapting their UV system to produce visible light without success. In 1990, they tried placing sulfur in a spherical bulb instead of a linear tube. Sulfur could give a good quality light, but did not work well in the linear tube. Other elements only gave marginal results in the spherical bulb. But when they tested sulfur in the spherical lamp they found what they hoped for: lots of good visible light with little invisible UV or infrared rays.
They began setting up "crude" lamps like this one (one of the first ten according to Ury) in order to learn more about the new light source. In the mid-1990s Fusion began trying to sell their sulfur bulbs with limited success. The lamp rotated at 20,000 rpm so that the temperature stayed even over the surface, and a fan was needed for cooling. The fan and spin motor made noise and reduced energy efficiency of the total system. Then they found that the bulbs lasted longer than the magnetrons used to generate the microwaves that powered them. Finding inexpensive magnetrons proved too difficult, and the company stopped selling the product in 2002.
Lamp characteristics: A quartz stem with notch near the bottom serves as the base. The notch locks the lamp into its fixture. The sphere has an argon gas filling, and the yellow material is sulfur condensed on the inner lamp wall. The pattern of condensation indicates lamp was burned base-down. Tipless, G-shaped quartz envelope.