General Electric Corporate Research & Development Laboratory
ID Number
1998.0050.16
accession number
1998.0050
catalog number
1998.0050.16
Description
As energy prices soared in the 1970s, lamp makers focused research efforts on raising the energy efficiency of electric lamps. A great deal of effort by many researchers went into designing small fluorescent lamps that might replace a regular incandescent lamp. These efforts led to modern compact fluorescent lamps that use bent or connected tubes, but many other designs were tried. This experimental "partition lamp" from 1978 shows one such design.
Soon after the 1939 introduction of linear fluorescent lamps, inventors began receiving patents for smaller lamps. But they found that the small designs suffered from low energy efficiency and a short life-span. Further research revealed 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. That's why fluorescent tubes in stores and factories are usually 8 feet (almost 3 meters) long.
Inventors in the 1970s tried many ways of putting a long arc path into a small lamp. In this case there are thin glass walls inside the lamp, dividing it into four chambers. Each chamber is connected in such a way that the electric current travels the length of the lamp four times when moving from one electrode to the other. So the arc path is actually four times longer than the lamp itself, raising the energy efficiency of the lamp. This unit was made by General Electric for experiments on the concept, though other makers were also working on partition lamps.
While the partition design works, it proved to be expensive to manufacture and most lamp makers decided to use thin tubes that could be easily bent and folded while being made.
Lamp characteristics: No base. Two stem assemblies each have tungsten electrodes in a CCC-6 configuration with emitter. Welded connectors, 3-piece leads with lower leads made of stranded wire. Bottom-tipped, T-shaped envelope with internal glass partition that separates the internal space into four connected chambers. Partition is made of two pieces of interlocked glass and is not sealed into the envelope. All glass is clear. No phosphors were used since the experimenter wanted to study the arc path.
General Electric Corporate Research & Development Laboratory
ID Number
1998.0050.07
accession number
1998.0050
catalog number
1998.0050.07
Description
As energy prices soared in the 1970s, General Electric, like other lamp makers, focused research efforts on raising the energy efficiency of electric lamps. One research program conducted by John Anderson at the GE Corporate Research and Development Laboratory in Schenectady, New York, sought to make a small fluorescent lamp that might replace a regular incandescent lamp.
Most fluorescent lamps, large and small, operate by passing an electric current through a gas between two electrodes. The current energizes the gas that in turn radiates ultraviolet (UV) light. The UV is converted to visible light by a coating of phosphors inside the glass envelope of the lamp. Electrodes are responsible for much of the energy lost in a fluorescent lamp and are usually the part of the lamp that fails. Instead of electrodes, Anderson's design used a donut-shaped, ferrite (an iron oxide compound) to generate an electric field. The field energized the gas.
He called his design a Solenoidal Electric Field (SEF) lamp. The one seen here is an experimental unit made around 1978. While the lamp worked in the lab, the electronics to control it were expensive and generated heat that needed to be dissipated. As with other electrodeless lamps, radio-frequency interference was a concern. By the early 1980s GE decided to shelve the SEF lamp and market a miniature metal-halide lamp instead. In the late 1990s, however, GE took advantage of the lower cost and higher capability of electronic components and marketed an electrodeless lamp that built on prior work—including the SEF lamp.
Lamp characteristics: No base. A 1.5" (outside dia.) toroid-shaped ferrite is mounted vertically inside the lamp and held in place by a wire cradle. The conducting wire is insulated with woven nylon and wrapped ten turns around the top of the ferrite. A woven nylon mat is wrapped around the ferrite under the conductor, and another is placed between the conductor and the top-plate of the mount-cradle. A metal lead extends from the bottom of the ferrite into the exhaust-tip where it spirals around a metal cylinder. Tipless, AT-shaped envelope.
General Electric Corporate Research & Development Laboratory
inventor
Spellman High Voltage Electronics Corp.
ID Number
1998.0050.15
accession number
1998.0050
catalog number
1998.0050.15
Description
The energy crises of the 1970s inspired inventors to try novel ideas for new light bulbs. One of the more unusual designs emerged from the drawing board of Manhattan Project veteran Leo Gross. Supported by Merrill Skeist at Spellman High Voltage Electronics Corporation, Gross designed a compact fluorescent lamp that he called a "magnetic arc spreader" (MAS).
The design took advantage of a fundamental aspect of electro-magnetism known since the early 1800s. When a current flows through a coil of wire, it produces a magnetic field. The arc discharge that travels between the electrodes of a fluorescent lamp can be affected by the presence of such a field. In the center of the MAS lamp seen here there is a copper coil. Current moving through the coil creates a magnetic field that spreads out the electrical arc within the lamp. The expanded arc energizes phosphor throughout the lamp's entire length.
The concept was tested at Lawrence Berkeley Laboratory, and General Electric became interested. In 1978 GE purchased a one-year license from Spellman in order to conduct further tests but determined that the necessary glasswork would make the lamp too expensive for commercial production. GE donated one of their test lamps to the Smithsonian in 1998—the only known surviving example of this experimental design.
Lamp characteristics: No base. Two stranded lead-wires extend about 2" from either end, and each end has one lead wire encased in a glass insulating tube. Two coiled tungsten electrodes are mounted in a hollow cylindrical envelope. The exhaust tip is near one set of leads, and the envelope has an internal phosphor coating. A coil of bare copper wire held together with black string is inserted into the center of the envelope. A current passing thru this coil spreads the arc between electrodes so that more of the phosphor is activated.
Telegraph relays amplify an electrical signal in a telegraph line. Telegraph messages travel as a series of electrical pulses through a wire from a transmitter to a receiver. The pulses fade in strength as they travel through the wire, limiting the distance a message can be sent. Relays remedy that problem by detecting a weak signal and automatically re-transmitting that signal down the line using a local power source.
Telegraph sounders convert electrical pulses into audible sounds and are used to receive Morse code messages. The message travels as a series of electrical pulses through a wire. Short pulses make a dot, slightly longer pulses make a dash. The sequence of dots and dashes represent letters and numbers. The pulses energize the sounder’s electromagnets which move a lever-arm. The arm makes a loud “click” when it strikes a crossbar and the operator translates the pattern of sounds into the original language. This sounder is rated at a resistance of 50 ohms.
Telegraph sounders convert electrical pulses into audible sounds and are used to receive Morse code messages. The message travels as a series of electrical pulses through a wire. Short pulses make a dot, slightly longer pulses make a dash. The sequence of dots and dashes represent letters and numbers. The pulses energize the sounder’s electromagnets which move a lever-arm. The arm makes a loud “click” when it strikes a crossbar and the operator translates the pattern of sounds into the original language. A resonator like this was used to amplify the sound, making it easier for an operator to hear his or her own sounder when working in a room filled with these devices.
The completion of the first transatlantic telegraph cable in 1858 was a cause for much celebration on both sides of the Atlantic. Tiffany & Company of New York purchased the cable remaining on board the USS Niagara after the successful completion of the cable and sold 4-inch sections as souvenirs. Each section of cable was banded at the ends with brass ferrules and had a brass plaque that read “ATLANTIC TELEGRAPH CABLE/GUARANTEED BY/TIFFANY & CO./ BROADWAY • NEW YORK • 1858.” The cable souvenirs originally sold for 50 cents and came with a reproduced letter of authenticity from Cyrus W. Field, the pioneer of the transatlantic cable system. The jubilation turned to jeers when the cable failed a few weeks later, and Tiffany never sold its supply of cable. In 1974 Lanello Reserves began reselling the transatlantic cable, and donated this object to the Smithsonian.