This circuit is from a 1964 Electronic Design. The sensor is an LDR and the transistors are general-purpose types. The circuit triggers when the light that falls on the sensor is cut off.
The circuit shown in the figure was suggested by National Semiconductor in its 1994 Linear...
This circuit can be controlled by an LDR causing an LED to flash at a frequency given by C2. The...
This hybrid power supply circuit was found in the August 1997 issue of Electronics Now magazine. The...