Water Level Indicator Electronic Circuit Using Transistor

Water Level Indicator :

Water Level Indicator
Water Level Indicator

Table Of Content :


  • Overview
  • Circuit Diagram
  • Circuit Components
  • Water Level Indicator with an auto ON-OFF Circuit
  • Applications Of Water Level Indicator Circuit

Overview :


We generally worry about the wastage of water, when we switch ON the motor and forget to turn it off. The Water Level Indicator employs a simple mechanism to detect and indicate the water level in an overhead tank or any other water container. We have posted already a Water Level Indicator and Controller using IC ULN2003. In this article, we are presenting a very useful, cheap and simple circuit using transistors (bc547) for beginners. This circuit indicates the level of water in the water tank using LEDs with transistors. you can use this project as a college project.



Circuit Diagram :

Circuit diagram of water level indicator
Circuit diagram of water level indicator




The connections arrangements are shown in the circuit diagram shown above. The +9V power supply or battery is used. In this circuit, we have used all the transistors as a switch. The water touches the wires contact with the base of each transistor, a small current flows through the base and turns on the transistor as transistor turns on, LED connected to it glows. LEDs will be turned on depending upon the level of water. We have used a buzzer with the last transistor as water touches the base of last transistor collector the collector and emitter connected and buzzer rings. The relay can be connected instead of the buzzer to auto control the water level in the tank.


Circuit Components :

  • Some pieces of wire
  • 5 – 9v battery + battery clip/power supply
  • 4 – BC547 transistors
  • 3 – 220-ohm resistors
  • 1 – Buzzer
  • 3 – LEDs




Water Level Indicator with an auto ON-OFF Circuit :

In this circuit we have used a relay instead of the buzzer as the tank will become full relay will be changing its state and will cut off the power. We are going to control the water pump with this relay, So you must use a powerful relay because a low power relay will be damaged as more impairs will cross through it.

Applications Of Water Level Indicator Circuit

  1. Stream level monitoring auto
  2. Pump controller Auto
  3. Cooling tower water level control
  4. Pool water level control
  5. Oil tank level control and indicator
  6. Automatically turn ON/OFF water pumps
  7. Sewage pump level control

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