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.
This circuit was obtained in the publication 101 Electronics Projects of 1979. The circuit can be...
Using a 100 uH inductor for L1, this circuit will oscillate around 1 MHz. The frequency will be...
This low current solenoid driver was found in an ancient American documentation. The solenoid must be...