The State Jal Boards
supply water for limited duration in a day. Time of water supply is
decided by the management and the public does not know the same. In such
a situation, this water alarm circuit will save the people from long
wait as it will inform them as soon as the water supply starts. At the
heart of this circuit is a small water sensor. For fabricating this
water sensor, you need two foils—an aluminium foil and a plastic foil.
You can assemble the sensor by rolling aluminium and plastic foils in
the shape of a concentric cylinder. Connect one end of the insulated
flexible wire on the aluminium foil and the other end to resistor R2.
Now mount this sensor inside the water tap such that water can flow
through it uninterrupted. To complete 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 working of the circuit is simple.
Timer 555 is wired as an astable multivibrator. The multivibrator
will work only when water flows through the water tap and completes the
circuit connection. It oscillates at about 1 kHz. The output of the
timer at pin 3 is connected to loudspeaker LS1 via capacitor C3. As soon
as water starts flowing through the tap, the speaker starts sounding,
which indicates resumption of water supply. It remains ‘on’ until you
switch off the circuit with switch S1 or remove the sensor from the tap.
The circuit works off a 9V battery supply. Assemble the circuit on any
general-purpose PCB and house in a suitable
cabinet. The water sensor is inserted into 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 on/off switch S1 to power the circuit with the 9V PP3