The sensor of this circuit found in Popular Electronics can be formed by a piece of fabric between two bare wire screens. When wet, the fabric will pass the current between the screens, triggering the alarm.
I found this simple circuit from an English magazine from 1984. The circuit can be easily...
Information about the high voltage transformer and the detecting circuits was not given in this...
The purpose of this circuit is to supply a direct reference voltage from the power grid. The...