We found this circuit in a 1966 documentation. The circuit is intended for a door opening system by the headlight of a car. The sensor is a photo-FET, an uncommon component today.
This circuit uses unijunction transistors and drives a small speaker through an output...
This circuit, found in a publication from the 1980s, can have its output voltage determined by the...
The operational amplifier for this circuit, found in a 1979 publication, may be the 741....