Water level indicator using transistor

 In this article we will discuss about the basic concept behind a water level indicator circuit and learn to build it.

A water level indicator indicates the water level in tank with LED indications, we will use three LED to indicate water level. Red LED for low water level, yellow LED for medium water level and green LED for full or high water level in tank. Further with this we can add up a buzzer when water tank goes empty.

Components Required:- 

1. Four Transistors BC547

2. Four resistors of quarter watt 1k and  three resistors of quarter watt 100E

3. Three LED and one buzzer

4. Five wires

5. 9 volt Battery 

6. Breadboard 

Circuit Diagram:-

Fig 1. Water level indicator circuit diagram 

Working:- In this circuit all four Transistors are being used as a switch, all switches remains open until base don't get supply. Base get supply when water level short respected transistor base wire and that transistor got switch on and give indication through LED and buzzer respectively according to their connections.

All five wires are hanged in water tank in which 101 wire touches the bottom of tank, Q4 transistor base set at just above the bottom level, Q3 at minimum water level, Q2 at medium water level and Q1 at high water level respectively as shown in Fig 1. 

When tank will be empty then buzzer will start to blow and we can turn on the motor manually and as the water level will go above, we will get indication through LEDs.

Applications :- To check water level of any tank. I made this circuit as mini project in my diploma course.

Author:- Amarjeet Singh Jamwal authored articles on Basic Electronics Engineering, Electric Traction, and Electronics Practical for INFO4EEE Website