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.
Using one unijunction transistor and two bipolar transistors, this circuit generates a signal from...
This circuit was found in an American 80s circuit manual. The components used are unusual. The...
We found this circuit in 1969 American documentation. FETs admit equivalents, as do transistors. The...