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 simple unregulated power supply with half-wave rectification is for small appliances that do...
Found in an American book from the 1960s, this circuit uses a photoelectric cell of the time as a...
In the publication in which we found this circuit, it is suggested for applications in clandestine...