The sensors of this liquid alarm are formed by two pieces of wire with the ends peeled off. The relay depends on the supply voltage that can be between 3 and 12 V. The transistors can also be the BC548.
The integrated circuit used is not common today, as it is a configuration of Motorola Linear...
Found in a 1968 Motorola documentation, this circuit operates at 1 kHz and can deliver 20 V from...
This circuit generates a linear sawtooth signal. The circuit was found in the December 1992 issue...