This simple rain, leak or moisture detector circuit appears in other places on this site with slight variations. This was obtained in an English documentation from the 70s.
This circuit activates a buzzer when the voltage applied to the input falls below a preset value in...
This simple window comparator based on the well-known LM339 was found in the June 1998 issue of...
This circuit, which can act as a shield, was found in a 1990 PE Hobbyst Handbook. The circuit...