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.
The circuit shown is from an old European publication. In it we have the way to activate a relay...
We found this circuit in a European publication from the 1990s. Transistors are still common types...
This circuit was found in an American documentation and can be added to common amplifiers of any...