We found this circuit in the 1989 Radio Electronics Experimenter. The circuit uses common components, and the thermistor is supposed to determine the value of the trim potentiometer.
This circuit was originally recommended to operate with the emitter of the previous circuit but...
When the probes of this circuit meet water, the relay closes its contacts. The circuit is from a May...
The power supply shown can supply voltages of approximately 0 V to 12 V with a maximum current of 4.5 A,...