16-11-2015, 02:38 PM
ppt for water level controller using 8051 microcontroller
This article explains you how to detect and control the water level in an overhead tank or any other container. This system monitors the water level of the tank and automatically switches ON the motor when ever tank is empty. The motor is switched OFF when the overhead tank or container is FULL. Here the water level of the tank is indicated on LCD (Liquid crystal Display). Using this system, we can avoid the overflow of the water. We have already seen How water level indicator circuit works using AVR Microcontroller in the earlier post. But, here we are designing the circuit which is used to detect and control the water level automatically in overhead tank using 8051 microcontroller.
In this system water sensing can be done by using a set of 4 wires which are placed at different levels in tank. DC supply probe is placed at the base of the tank.
Water Level Controller using 8051 Circuit Principle:
This system mainly works on a principle that “water conducts electricity”. The four wires which are dipped into the tank will indicate the different water levels. Based on the outputs of these wires, microcontroller displays water level on LCD as well as controls the motor.
Circuit Components:
At89c51 controller
At89c51 programming board.
16*2 LCD
5V Relay
Bc547 (NPN) transistors – 5
Resistors (1K) – 4
Resistor – 330 ohm
AC Motor
Pot – 10k
Programming cable
Connecting wires
Water Level Controller using 8051 Circuit Design:
The main heart of this project is AT89C51 microcontroller. The water level probes are connected to the P3.0, P3.1, P3.2, and P3.3 through the transistors. Port P2 connected to the data pins of LCD and control pins RS, RW and EN of LCD are connected to the P1.0, P1.1, and P1.2 respectively.
Initially when tank is empty, LCD will display the message EMPTY and motor runs automatically. When water level reaches to quarter level, now LCD displays QUARTER and still motor runs. For further levels, LCD displays the messages HALF and ¾ FULL.
When tank is full, LCD displays FULL and motor automatically stops. Again motor runs when tank is empty.
The probes are arranged in such a way that they sense ¼th, 1/2, ¾th and even full levels as they are placed with equal spacing one above the other with the bottom positive probe. A positive voltage supply is placed at the bottom of the overhead tank, and a full-level probe is placed in the tank and the other end is connected to the base of the transistor Q4 through a resistor R16.
Whenever the water level rises to the maximum, then current flows through the base of the transistor and the collector voltage becomes low and is interfaced with the port p2.4. The programming is done in the microcontroller and sends the data to the microcontroller and LED. D1 indicates the level of water and the motor switches off automatically whenever the water level goes below the full-level probe, and then the base of the transistor Q2 opens by switching it off; the collector voltage of Q2 is high at P2.4, which means the tank is not full and the same process is applied to the remaining sensing probes ¼, 1/2, 3/4 as they are connected to the base of the transistors q1,q2,q3 and interfaced with the ports p2.5, p2.6, and p2.7 while programming is done within the microcontroller. The LED D3, D4 and D5 glow as an indication of the levels (¼, 1/2 and empty), and then the transistor gets on and the motor will be on.
The ports P0.0, P0.1, P0.2, P0.3 and P0.4 are interfaced with the LEDs for the purpose of indicating the levels and are connected to the resistors. The port P0.5 is used to control the pump and the transistor Q6 remains on as the relay also gets activated while the port P0.7 is connected to the LED D7 as an indication of low level in the sump and the LED glows.