This circuit with a maximum current of 50 mA was found in the August 1998 issue of Electronics Now magazine. The integrated circuit used is not very common today.
This circuit came out in an English publication of 1976, but it can be easily assembled using...
When light fails to focus on the sensor, a common photo-transistor, the relay closes its contacts....
This traditional clock circuit with common CMOS components with discrete logic functions was found...