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.
Line voltage compensation (CB8816E) This circuit for the alternating current line (AC line) was...
This general-purpose preamp configuration was found in the 1960 Mullard transistor reference...
The integrated circuit of this 1976 configuration is the 7400 and the type crystal in televisions of the...