This circuit was found in a 1992 publication. What it does is to light an external lamp when it gets dark. The trigger point adjustment is made in a potentiometer or trimpot and the sensor is a common LDR.
We found this circuit in an American documentation from 1977. In it we have the way to use an...
This circuit is from a 1986 Revista Española de Electrónica. It consists of an amplifier with...
This circuit, which uses a planar silicon sensor, is from a 1964 Electronic Design. The component...