Continuous monitoring of level in an over head tank is an hectic task as we have to turn on the motor pump when ever the level of water is low and to monitor all the time till the water has filled completely in the tank else the water would over flow, to avoid this job of monitoring the water level we have assigned this burden to the technology.
Now well learn how to built a water level monitoring system and how to automatically switch on and switch off the motor.
Basic block diagram ::
Working of devices:
H-bridge: Micro controller has logic high on all the pins and certain amount of current passing through them, but the current present in the pins is not sufficient to run the motor, so we use the amplifier to obtained the required rated current, to get this one has to use a multi staged amplifier to get the required rated current of the motor, we can normally use a class c amplifier to get the required current, but if we want to change the direction of rotation of motor then we have to physically change the direction of motor, so in order to avoid these issues we have come with a concept called as h-bridge.
the working of the h-bridge is such that when logic [1 0] to the transistors 1 and 4 is given to the pins of the ic then the motor rotates in the clock wise direction and when the input[0 1] to them then the motor rotates in the anti clock wise direction, and if the logics[1 1] or [0 0] is given then the motor will be stopped.
Motor:
here we use a dc motor which work on 12v dc voltage and a current of 200 mA, this rotate in clock wise for[1 0] and in anti clock wise for [0 1]
Working of the project:
We connect 2 pins of the micro controller with some connectors and place the other end of the connectors in the over head water tank in 2 different positions that is one at the extreme top till where we want to fill the tank and one at the bottom i.e the position of the water in the tank at which we want the motor to turn on
then we connect connectors to the ground voltage and then place this connection at the extreme bottom of the over head tank such that this will touch the bottom of the tank
let us name the pin of uc which is at the bottom of the micro controller as low and at the top as high.
now as the initial condition let us consider the water level in the tank to be at the half, so the ground and low pin are shorted and the logic level 0 is supplied to this pin1 of ic and as the high is not in contact with ground this will give us logic 1 to the ic and at this level we dont want the motor to be turned on, so now we have pin 2 as high and pin 1 as low and now we give either [1 1] or [0 0] to the h-bridge ic such that the motor is off
Now if the water level is reduced such that the water dosent even touch the low pin then the low pin also supply logic high and high pin also supply logic high and now we need the motor to turn on so now we give either [1 0] or[0 1] to the micro controller as we dont consider the direction of rotation of the motor.
As the motor is turned on the water level in the tank increases gradually, when the water level increases to the pin high then both the pins both give logic zero since they are shorted with the ground, now we have to turn down the motor so we give [1 1] or [0 0]. In this way the water level is monitored itself and the motor is automated.
Circuit diagram:
Power supply:
Unlike other projects we need here both 5v dc supply along with 12v dc supply to drive the motor so here we use 2 voltage regulators and a basic 15v transformer to convert the 220v dc to the required voltage rating
