Description in detail: It mainly consist of following blocks
1. Potentiometer and pulley arrangement: We have to measure the water level, for this purpose we are going to use a pulley-float/potentiometer arrangement. Pulley will be hanged above the water and a float will be resting on the water surface using a rope. And potentiometer will be fixed at the center of the pulley. So as the water level goes up and down, respectively pulley and potentiometer will rotate. So eventually water level is converted into resistance of potentiometer. A constant current source is used to pass current through this potentiometer, so as to get a voltage drop. This voltage is given to amplifier.
2. Amplifier: As the voltage output across the potentiometer is less, it has to be increased to 0 to 5 volts range. We are going to use linear amplifier for this purpose.
3. Voltage to frequency converter: The main part of our project is microcontroller (89s51) which reads only digital input (0V & 5V) But the output of Amplifier is in analog form, so it has to be converted into digital format, for this purpose we are going to use Voltage to Frequency converter to convert analog output from amplifier into the digital output to be given to microcontroller
4. Microcontroller: This is the CPU (central processing unit) of our project. We are going to use 89s51, because it belongs to the 8051 family. The various functions of microcontroller are like
I. Reading the digital input from Volt to Freq converter which is derived from Potentiometer and pulley arrangement II. Sending this data to LCD so that the person operating this project should read the values of Water level. III. Storing the data into EEPROM memory and display it later using keypad IV. Sending the values of temperature and light to the computer using serial port
5. EEPROM: We are going to use AT12c02 as a EEPROM memory, it is Electrically erasable programmable read only memory. It stores the data even if power supply is disconnected. This is used to store the water level along with date and time when it is recorded.
6. LCD: We are going to use 16x2 alphanumeric Liquid Crystal Display (LCD) which means it can display alphabets along with numbers on 2 lines each containing 16 characters.
7. PC Interfacing: We are going to use max 232 IC for pc interfacing, the values of temperature and light will be sent to pc when the key is pressed
8. Keypad: Various operations of keypad are as following,
I. Display current level II. Display current flow III. Display previous records IV. Erase previous records V. Send data to Computer VI. Set logging time VII. Set current time

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