Water supply reminder after water outage

This circuit can remind you in time when the water supply is restored when the tap water is cut off.

The core component of the circuit is a homemade tap water detector. You can use two pieces of foil: one is aluminum foil and the other is plastic foil. Roll them together into a cylinder, the size of which should fit into the tap. Connect one end of a wire to the aluminum foil of the detector cylinder. Connect the other end to resistor R2. To complete the detection loop, use another wire to connect the ② and ⑥ pins of IC1 to the tap or water pipe.

The timer 555 chip is connected as a multivibrator, and the multivibrator can only work properly when there is water flowing through the tap. If there is a water outage, IC1 will not oscillate. When there is a water outage, just close S1, and once the tap water is restored. Even if the tap is closed, the detection circuit can complete the circuit through the tap water, causing IC1 to generate a 1kHz oscillation, which is sent to the speaker LS1 through pin ③ and C3 to emit a 1kHz reminder sound. The 1kHz reminder sound is retained until S1 is disconnected or the detector cylinder is removed from the tap. The circuit is powered by a 9V battery.