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.
The circuit shown in the figure on the right can be used on a data transfer bus with the use of an...
This timer was found in Japanese documentation from the 1960s. The transistor can be replaced by...
We found this circuit in a documentation from the 90's. The circuit can be assembled with 741...