This circuit was suggested by Signetics in 1980s documentation. The circuit makes use of the hard-to-obtain component of our day. It is for reference only.
This circuit, obtained from a 1965 magazine, can still be assembled using some modern equivalent...
This circuit was found in the October 1989 issue of Radio Electronics magazine. It drives an...
This circuit detects a light window using two operating systems. The circuit is from a July 1992...