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 uses an operational that is not currently common. We found it in an old American...
This circuit uses two transistors to obtain low frequency sinusoidal signals. We found it in a...
This amplifier can be powered with voltages between 2 and 5 V with power up to 100 mW. The minimum...