2N1992 semiconductor manufactured by Sylvania, listed as 2N1992 (circa 1979).

2N1991 semiconductor manufactured by Sylvania, listed as 2N1991 (circa 1979).

2N1990 semiconductor manufactured by Sylvania, listed as 2N1990 (circa 1979).

2N1989 semiconductor manufactured by Sylvania, listed as 2N1989 (circa 1979).

2N1988 semiconductor manufactured by Sylvania, listed as 2N1988 (circa 1979).

2N1987 semiconductor manufactured by Sylvania, listed as 2N1987 (circa 1979).

2N1986 semiconductor manufactured by Sylvania, listed as 2N1986 (circa 1979).

2N1985 semiconductor manufactured by Sylvania, listed as 2N1985 (circa 1979).

2N1984 semiconductor manufactured by Sylvania, listed as 2N1984 (circa 1979).

2N1983 semiconductor manufactured by Sylvania, listed as 2N1983 (circa 1979).

2N1982 semiconductor manufactured by Sylvania, listed as 2N1982 (circa 1979).

2N1981 semiconductor manufactured by Sylvania, listed as 2N1981 (circa 1979).

2N1980 semiconductor manufactured by Sylvania, listed as 2N1980 (circa 1979).

2N1975 semiconductor manufactured by Sylvania, listed as 2N1975 (circa 1979).

2N1974 semiconductor manufactured by Sylvania, listed as 2N1974 (circa 1979).

2N1973 semiconductor manufactured by Sylvania, listed as 2N1973 (circa 1979).

2N1972 semiconductor manufactured by Sylvania, listed as 2N1972 (circa 1979).

2N1971 semiconductor manufactured by Sylvania, listed as 2N1971 (circa 1979).

2N1970 semiconductor manufactured by Sylvania, listed as 2N1970 (circa 1979).

2N1969 semiconductor manufactured by Sylvania, listed as 2N1969 (circa 1979).