Water level indicator circuit using CMOS ICs

Posted on Feb 5, 2014

A very simple low cost water level indicator circuit can be designed using this schematic circuit. This water level indicator is based on a simple CMOS IC CD4066 and indicates the amount of water present in the overhead tank and also gives an alarm when the tank is full. When the water is empty the wires in the tank are open circuited and the 180

Water level indicator circuit using CMOS ICs
Click here to download the full size of the above Circuit.

K resistors pulls the switch low hence opening the switch and LEDs are OFF. As the water starts filling up, first the wire in the tank connected to S1 and the + supply are shorted by water. This closes the switch S1 and turns the LED1 ON. As the water continues to fill the tank, the LEDs2, 3 and 4 light up gradually. When the water is full, the base of the transistor BC148 is pulled high by the water and this saturates the transistor, turning the buzzer ON. The SPST switch has to be opened to turn the buzzer OFF.

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