19-01-2012, 01:40 PM
WORKING PRINCIPLE:
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Attach length copper wire to one stick and make two points (top and bottom) on other stick with copper wire; and mark them point A, B, C as shown in the diagram. Connect points A, B and C to the main circuit. The IC 555is used in the circuit as an astable multivibrator. The IC is an 8pin duel-in-line IC. When there is water in between the points A and C, pin no 3 voltage of the IC becomes high and transistor BC 148 operates the relay. As a result the motor starts and fills the tank. When the volts reaches the top level. A comes in contact with Band pin no3 voltage becomes low. The relay then changes the position and motor becomes OF. When the water level becomes low, the motor starts again.
