Wastage of water is really an issue in places where they use overhead tanks. Monitoring of water level is really a difficult task in those places and it could also lead to wastage of water and power. The above circuit shows a simple water level indicator system based on Tranistors and LED's. This circuit could give a simple and cost effective solution for this problem. This circuit was a simplified version of "Water level indicator" published in Instructables by Raikut.
WORKING OF CIRCUIT:
The circuit schematic comprises of totally two parts. Indicator section for indicating the water level present in the tank and Alarm section for alerting the people to turn off the pump once the tank is completely filled. The LED's are used for indicating the level whereas the transitors are used as a switching devices. A simple buzzer was used to sound provide the overflow warning. This circuit works based on the conductive property of the water.
The positive line of 6V is inserted into the tank, when there is no water in the tank all the three transistors will be in off state. When the water pump is turned on water starts filling the tank, when the water reaches the 1/4 level of the tank it comes in contact with the 1/4th level wire which is connected to the base of the transistor Q1. The water will provide a path for the current to flow from supply to the base of the terminal. This turns the tranistor Q1 in turn Red LED D1 which indicates that 1/4th level of tank is filled with water.
In the same way when the water reaches the 1/2th level it turns on yellow LED and when the tank is full it turns on the green LED. By this way the LED's help us to determine the level of water in the tank. Coming to the alarm section when the tank is full it turns the transistor Q4 which was wired as a switch to turn on the Buzzer which alerts the person to turn off the pump in order to avoid overflow of tank.
The switch given was used to turn off the alarm after the person is alerted. But do remember to turn the switch on before turning the Pump on or else the alarm won't work. For advanced version of this circuit refer to this article "Water Level Indicator Circuit with Alarm on Instructables".
NOTE:
- You can increase various stages of water level by increasing the number of transitors and LED's in the circuit.
- Try Using different colors of LED to avoid confusion or use a marker to write the appropriate water level near the LED's.
