This simple power supply circuit triggers when the light on the LDR reaches the level set on the potentiometer. The circuit is from an Electronics Now from July 1995.
This circuit for cars with mechanical ignition systems was found in the Electronics Experimenter handbook...
This code practice circuit was found in a 1990s issue of Radio Amaterur Today magazine. It...
The circuit presented was found in the Linear Applications Handbook of the National Semiconductoir of 1994....