This circuit triggers a buzzer or other warning device when the light falling on the sensor is cut off. We found it in the Encyclopedia of Electronic Circuits Volume 5 of 1995.
This circuit was found in an American magazine 73 for radio amateurs of the 80s. It is an...
Found in American documentation from the 1980s, this circuit can be designed with equivalent...
This circuit is from a 1977 documentation. It is powered by the power supply of the circuit under...