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.
An unusual looking type of compact fluorescent lamp (CFLs) has spiral tubes, like this "Spiralux" lamp made by Duro-Test in 1996. Several manufacturers developed and now produce spiral CFLs. While the equipment to make these spiral tubes proved expensive to develop, the design addresses two problems.
CFL engineers faced a problem stemming from the fact that energy efficiency in fluorescent lamps depends in part on the distance the electric current travels between the two electrodes, called the arc path. A long arc path is more efficient than a short arc path. But most residential fixtures are designed to accept lamps the size of ordinary incandescent bulbs. So CFLs have been made with a variety of bent, folded, and connected tubes--all intended to put a long arc-path into a small lamp, the spiral design being one such.
The second problem centered on how light generated by the lamp interacted with shades and reflectors on fixtures. Most incandescent lamp fixtures are designed to use frosted or so-called soft white lamps. The coatings prevent the filament from being seen, making it look like the entire glass bulb is glowing. Shades and reflectors used in regular fixtures are designed using the science of optics to spread and direct the light in predictable patterns. CFLs, with their glowing tubes, are not shaped correctly for regular fixtures, causing light from the fixtures to be emitted in undesired patterns. Spiral CFLs closely mimic the shape of a glowing incandescent lamp so the optical design of the fixture operates as intended.
Lamp characteristics: Brass, medium-screw base with plastic skirt and glass base-insulator. Spiral-shaped discharge tube with internal phosphor coating, mercury, and two tungsten electrodes. The shape is intended to simulate an ordinary A-lamp.
A major hurdle that makers of compact fluorescent lamps (CFLs) have faced stems from the unusual shapes of the lamps, as compared to traditional incandescent lamps. Consumers have grown used to what light bulbs "are supposed" to look like. Many have rejected CFLs for that reason despite the potential cost savings.
As lamp makers refined their understanding of the new product, designs were introduced to meet consumers' preferences for less-intrusive styles. Duro-Test developed a series of five modular CFLs around 1996, including this "Duro-Brite" unit that has a removable glass globe covering the twin-tube lamp. Another unit in the collection sports a removable glass reflector. The base-units contain the lamp's ballast and starter, and the tube assemblies themselves are interchangeable.
This unit is a modular CFL with three components: a tube assembly, an adapter, and a glass cover.
Lamp characteristics: Tube assembly is a twin-tube unit mounted on a plastic base. The adapter has a medium-screw base-shell with an insulator that is part of the plastic skirt housing the ballast. A G23 socket is on top for the tube assembly, and key-slots are molded around the edge to attach the cover. Cover is a G-shaped, clear-glass envelope with aluminum collar at bottom. There are stamped protrusions on the inside of the collar to mount the cover onto the adapter. Electrical rating is 13 watts.
One method that companies have long used to minimize production costs is to design products that use many of the same parts. In the early 1990s Duro-Test Lighting used this approach in a series of modular compact fluorescent lamps (CFLs).
Modular CFLs are designed so that specific parts can be replaced if they fail. This allows the reuse of expensive parts that still work. In this particular lamp, the fluorescent tube and the reflector enclosing it are made as one piece; the base-unit that houses the ballast and starter are another. In addition to allowing one to replace the tube assembly if it failed, one could swap different assemblies. The reflector lamp could be changed to a decorative lamp for example, without having to remove the base-unit.
Since the price of electronic components has dropped since this lamp was made, the economic reasoning behind this feature is less persuasive.
Lamp characteristics: Two-piece, modular compact fluorescent lamp including a base-unit and a tube assembly. The base-unit has a medium-screw base-shell with plastic insulator, and a plastic skirt that houses a ballast and a starter. A socket on top accepts a plug-in base. Tube assembly includes plastic plug-in base, a fluorescent tube with two electrodes, mercury, and a phosphor coating. A glass R-shaped envelope with silvered coating serves as a reflector and is glued to the tube assembly's base.
Package is a J-lead plastic chip carrier and D (dip). This 8-bit CPU was an attempt to complement a mini-computer but failed due to the 32-bit architecture successes - it was the competitor to the Intel 4004 chip set
Original switch key put in on introduction of the second dynamo, November, 1881. A wooden knife switch mounted on a wooden base. Four binding posts. Used in the Hinds-Ketchum printing plant as part of the first commercial installation of the Edison lighting system.
Original safety plugs put in on system in December, 1881. Prior to this a small section of lead wire had been soldered into the trunk line and there were no safety plugs [fuses] on any of the main lines to the lamps. Used in the Hinds-Ketchum printing plant as part of the first commercial installation of the Edison lighting system
Marked: "Weston / Model 519 / No. 2367 / Weston Electrical Instrument Corp. / Newark, N.J. U.S.A." Unit includes carrying case. Specimen is essentially a voltmeter designed for the purpose of measuring voltages used in a radio both at battery terminals and at tube sockets. No auxiliary power supply is employed. The instrument has voltage ranges of 200, 80, and 8 volts, and a current range of 20 milliamperes. Voltage ranges have a resistance of 1000 ohms per volt. A function switch on the unit and adapter sockets for tubes permit various tests as outlined in the manual. Reference: "Instructions for the Use of Weston Model 519 Radio Set Tester," undated, furnished with unit.
Cord length: 10.75". Throat microphone designed and developed for the US Army Air Force by Stuart Ballantine of Ballantine Labs., Inc. Boonton, NJ. Known as a "talking collar" this device permitted aviators to communicate without removing hands from aircraft controls. References: US Patents 2121778 through 2121781, and 2122191, issued 28 June 1938 to Stuart Ballantine.
According to a newspaper account, the Army had been secretly testing Ballentine's throat microphones for "more than three years" at the time the patents issued. Stephen McDonough, "Talking Collar," NY Journal and American, 17 July 1938; Newark, NJ, Sunday Call, 17 July 1938.
Thomas Edison used this carbon-filament bulb in the first public demonstration of his most famous invention, the first practical electric incandescent lamp, which took place at his Menlo Park, New Jersey, laboratory on New Year's Eve, 1879.
As the quintessential American inventor-hero, Edison personified the ideal of the hardworking self-made man. He received a record 1,093 patents and became a skilled entrepreneur. Though occasionally unsuccessful, Edison and his team developed many practical devices in his "invention factory," and fostered faith in technological progress.
Inventing a new technical device not only involves creating the device itself, but often entails creating special tools to produce the device or the component pieces of the device. Thomas Edison conducted experiments on hundreds of different types of natural fibers in his search for a material that would serve as a light bulb filament.