About 1000 times more light-sensitive than photovoltaic cells, these photoconductive cells are designed for light-dependent control applications. They are available in four basic sizes: a "Compactron" type, a 9-pin type in a conventional tube envelope, a medium size, and a miniature type, each with flying leads.
The "Compactron" type and the two smaller cells are end-illuminated, while the fourth is side-illuminated. The units, manufactured by the Receiving Tube Dept. of General Electric, Owensboro, Ky., are hermetically sealed to protect the photoconductive material from moisture.
The "Compactron" type Z-2946 and the conventional-tube envelope type 7427 are all-glass, while the medium-size cell Z-2963 and the miniature Z-2755-1 are of metal-to-glass construction. All the cells operate over a range of 1400 Å. The wavelength of maximum response is 5500 A.
Both the "Compactron" type and the 7427 have essentially the same ratings. Power dissipation is about 400 mW, max current is 50 mA, and max applied voltage is 350 V.
The "Compactron" envelope, be-cause it is bottom-evacuated, lends itself to the end-illumination design. Its 12-pin feature provides extra tie points, socket adaptability, and ruggedness. Seated height is less than 1 in. It can be used for street-lighting control and other area or residential-lighting applications. The seated height of the 7427 is 2.25 in.
The medium-size cell was developed for CRT picture-brightness and contrast control. Its power dissipation is about 250 mW, max current is 20 mA, and max applied voltage is 250 V. The outside diameter is a little more than 0.6 in. and height, excluding leads, is about 0.3 in. (Electronic Design, Nov. 8, 1961, p. 54)