This circuit has 4 operating modes and was found in the 1995 Encyclopedia of Electronic Circuits Volume 5. The circuit works with light or heat sensors.
This configuration has already been used several times in many of our projects and can be found in...
This circuit is from Popular Electronics from October 1981. The diode can also be 1N4004 and the...
This circuit was found in a Radio Electronics Constructor, English magazine of April 1976; The...