This circuit was found in an American documentation of the 90s. Optical resources with the LDR as a lens can help in obtaining directivity and sensitivity.
This circuit is from a 1975 magazine, but it is still current as all components are common. The...
This PNP transistor power stage was found in the May 1969 issue of Radio Electronics magazine. The circuit...
This circuit is suitable for incandescent lamps but can be adapted to work with LEDs. The circuit is...