AUTOMATIC WATER LEVEL INDICATOR
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INTRODUCTION:
Generally most houses and buildings have two water tanks, one situated on the roof and another one on the ground or sometimes underground. The received water supply is allowed to fill the lower tank first, and a water pump motor is then switched ON manually so that the water from the lower tank is pumped and shifted into the upper tank on the roof. Once the water from the lower tank is completely transferred into the upper tank, the pump is again manually switched OFF.



PRINCIPLE:
It is based upon the principle of conduction of water. We give earth to the water. When the water rises in the tank then the desired pins are conducting.



OPERATION:
One electrode probe is with 12V DC is placed at the bottom of tank. Next probes are placed step by step above the bottom probe. When the water/liquid comes in contact with the electrode tip, a conductive path is established between the sense electrode and the tank wall/reference electrode, which in turn makes the transistors conduct to glow LED and indicate the level of water. The ends of probes are connected to corresponding points in the circuit as shown in circuit diagram. Insulated Aluminum wires with end insulation removed will do for the probe.



RESISTANCE
The electrical resistance of an object is a measure of its opposition to the passage of a steady electric current. An object of uniform cross section will have a resistance proportional to its length and inversely proportional to its cross-sectional area, and proportional to the resistivity of the material.