Flashback > 10 Years Ago
MAY 28, 1992
A conversion efficiency of 17.1%, claimed as a world record, was attained using a polycrystalline-silicon solar cell. Scientists at Sharp Corp., Osaka, Japan, regard their achievement as a significant milestone on the road to practical application of photovoltaic technology as a next-generation power source. Several factors contributed to the cell's efficiency. For one, finely machined grooves on the cell's surface reduced reflectivity of solar radiation. In addition, the surface contact pitch was narrowed from 3.7 mm (used in an earlier version) to 2.5 mm, which lowered the cell's surface resistance. Finally, the cell-fabrication process was optimized, increasing efficiency by 0.2%. (Technology Newsletter, p. 23)
Flashback > 25 Years Ago
MAY 24, 1977
New circuits for AM radios and transmission equipment will have to be designed next year after the Federal Communications Commission gives the go-ahead to stereophonic broadcasts on the AM band. Precisely how those circuits will have to operate depends on which of the five AM stereo transmission techniques proposed to the FCC emerges as a standard.
Once AM stereo is on the air—perhaps by the end of this year and likely by the middle of 1978—the demand for high sound quality at the transmitting and receiving ends is likely to grow. Circuits will have to be designed to increase the bandwidth and cut the distortion, as well as to encode and decode the stereo information, in AM transmitters and receivers. (News, p. 28)
Flashback > 40 Years Ago
MAY 24, 1962
Probably no area in electronics has expanded as fast as semiconductor diodes. Need a rectifier diode? You can chose from over 6000 types. A reference or regular type? Select it from more than 4000. Even in the exotic areas, such as varactors and tunnels, the choice is growing. There already are 250 tunnel-diode types, for example. In all, the number of semiconductor diodes has more than tripled in the past three years—up to 15,000 types.
The circuit designer, to zero in on an optimum type for his application, must:
- Recognize device limitations
- Properly interpret ratings and characteristics
- Apply appropriate design safety factors. (Special Report, p. 36)
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