11. Bridge Rectifier: Bridge Rectifier is actually a bridge of Diodes 1N4007.This is used to convert 12 V AC (coming from Transformer) to 12 V DC which is supplied to circuit. LEDs: Light Emitting Diodes, Placed in circuit, to show level of water in Tank. These diodes are operated at 1.5 V 470 ohm Resistors: 470 ohm Resistors are installed in the circuit because LED is Operated at 1.5 V, and we are having 4.7 V there, so in order to decrease the voltage across LED we placed 470 ohm resistors
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15. Can be used to measure underground storage of water.