This is the circuit diagram of drinking water alarm. This water alarm circuit is purposed to help the people from long wait for water supply as it will inform them as soon as the water supply starts.
The heart of this water alarm circuit is actually a little water sensor. For fabricating this water sensor, you will need two foils-an aluminium foil as well as a plastic foil. It is possible to assemble the sensor by rolling aluminium and plastic foils in the form of a concentric cylinder. Connect one end of the insulated versatile wire on the aluminium foil and the other end to resistor R2. Now mount this sensor within the water tap such that water can flow by way of it uninterrupted. To accomplish the circuit, connect another wire from the junction of pins 2 and 6 of IC1 to the water pipeline or the water tap itself.
The operational of the water alarm circuit is very simple. Timer IC 555 is working as an astable multivibrator. The multivibrator will operate only when water flows by way of the water tap and completes the circuit connection. It oscillates at about 1 kHz. The output of the timer at pin 3 is wired to loudspeaker LS1 via capacitor C3. Immediately after water goes flowing through the tap, the speaker will start sounding, which signifies resumption of water supply. It stays ‘on’ till you switch off the circuit with switch S1 or take out the sensor from the tap. The circuit can be operated with a 9V battery supply.
You need to assemble the circuit on any standard PCB and house inside a appropriate cabinet. The water sensor is inserted in to the water tap. Connect the lead coming out from the junction of 555 pins 2 and 6 to the body of the water tap. Use the on/off switch S1 to activate the circuit with the 9V PP3 battery.