SIMPLE WATER LEVEL INDICATOR CIRCUIT USING TRANSISTORS

Here’s a SIMPLE WATER LEVEL INDICATOR CIRCUIT. It is best suited for overhead water tanks to display the amount of water. The circuit consisting of 3 LED’s used to indicate minimum, medium and maximum levels. It is possible to increase the count of indicator LED’s and make it more convenient. The circuit is powered by a 6V battery and it consumes only very less current.

COMPONENTS USED

COMPONENTS	RATING	QUANTITY
Transistors	BC548C	3
Led Bulbs		3
Sensing Probes	18 SWG COPPER WIRES	4
Resistors	220KΩ	3
	220Ω	3
Battery	6V	1

CIRCUIT DIAGRAM

Circuit Diagram

The circuit consisting of 4 sensing probes which is dipped in water to sense the level of water. The probe A is connected as common to other three, which should be at the bottom most part of the water tank, also it act as a reference level. The probes B, C, and D are set as minimum, middle and maximum level respectively. Assemble the circuit on a general purpose PCB and enclose it in a casing and mount it inside your home with the indicator LED’s pointing out of the box. A short length three, 18 SWG copper wires can be used as sensing probes and for common sensor Probe A, a bare copper wire can be used.

When water in the tank touches the probe A and B both, a small current flows from A to B through water and to the base of transistor T1 via a 220KΩ resistor. As a result the transistor conducts causing the LED1 to glow. Similarly, when water touches sensor C, LED2 glow and indicates that the tank is half-filled. Finally, when the water touches sensor D, LED3 glows and indicates the tank is completely filled. You can also combine a WATER TANK OVERFLOW ALARM CIRCUIT with it.