This circuit was found in a 1966 General Electric documentation. It makes use of direct contact water sensors and therefore requires an isolation or low voltage relay drive transformer.
The integrated circuits in this application are not very common today. One consists of an A / D...
This CMOS oscillator circuit generates signals up to a few megahertz, depending on the capacitor value....
This circuit was found in a 1977 American manual. The integrated circuit is from the time....