Build your own water level Indicator
Everyone will have an overhead water tank in their houses. Isn’t it a very tiring work of switching on and off the motor every time the tank is empty? And it is a very timely time. If forgot once, may lead to lackage of water when you are trapped inside…
Here is a small project which uses a relay and 8051 microcontroller which will switch ON the motor when the water level reaches the minimum threshold and turns OFF automatically when full.
Isn’t it great?
Every project can be done in two methods.
- By using analog circuit.
- By using a micro processor (digital).
Here are the components required :
A wooden or plastic scale (length equal to the depth of the tank) , 8051 microcontroller kit (programming and developing kit) , 5V-240V relays, LED’s (green and red for convenience), connecting wires, OpAmp LM324, 5V power supply, a bit of your programming logic.
We are going to mark two levels in the tank. One is for the minimum level, and one for the maximum level.
When water reaches minimum level, the motor automatically turns ON.
When water reaches maximum level, the motor turns off.
Requirement of relay :
The input and output of the microcontroller is only 5V. This is not enough to drive a motor. Right?
Hence we use a relay. We can differentiate the relay as two separate circuits. One, low voltage circuit (DC), second, the HV circuit (AC).
Whenever the input of the LV circuit is high, the HV circuit acts as a short circuit. When input is low, the HV circuit acts as an open circuit.
Hence the output, of the microcontroller can be used to drive a motor.
Requirement of OpAmp :
Water has its own resistance. Hence the complete 5V may not be given at the input. Hence we use OpAmp to bring the voltage to Vsat.
We leave a floating positive terminal of 5V at the bottom of the tank. We tie up two strips of open copper wire to a plastic or wooden scale which are called as maximum and minimum levels.These strips of wires are connected as level inputs to the microcontroller. Whenever water is above the maximum level, both the inputs to the 8051 are high (water is a good conductor of electricity) . This is an indication to the motor to turn OFF. When the level is lower than the minimum level, both the inputs to the microcontroller are low. This indicates the motor to TURN ON.
Hope you got the clue.
You can connect the LEDS to the output of the microcontroller in a format where red glows when the motor is off and green glows when the motor is ON.
CLUE: Connect then in reverse bias with respect to each other.