This circuit was found in a 1985 documentation. It provides an audiovisual indication of the presence of moisture or water in the sensor. The circuit can be powered by voltages from 6 to 9 V.
This circuit was found in Radio Electronics from July 1990. The circuit produces the sound of the...
This circuit was obtained in an old documentation and is characterized by the high sensitivity...
This circuit was found in an old American publication from the 70s. It flashes a warning lamp,...