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What is the presentation is about ? IN this project we show that how we convert the analogue fuel meter into digital fuel meter. IN every car there is one fuel tank and with the help of floating boll we check the position of fuel level and then small needle on the car panel show the total quantity of fuel by marking indication.

DIGITAL LIQUID LEVEL INDICATOR This article illustrates the construction and working of a liquid level indicator. Such an indicator is used in tanks to indicate the level of liquids and alert us when the tank is full. So by this circuit we can monitor the various levels of the tank and can avoid spillage of water, and also we can configure our supplies according to the various levels of tank. Such module or circuit can be installed in big buildings where manual monitor of tanks is difficult and its indicator can be placed at some centralised place.

DIGITAL LIQUID LEVEL INDICATOR

GAUGE :- The gauge is also a simple device. The current from the sender passes through a resistor that either wraps around or is located near a bimetallic strip. The bimetallic strip is hooked up to the needle of the gauge through a linkage. As resistance increases, less current passes through the heating coil, so the bimetallic strip cools. As the strip cools, it straightens out, pulling the gauge from full to empty. The bimetallic strip is a piece of metal made by laminating two different types of metal together. The metals that make up the strip expand and contract when they are heated or cooled. Each type of metal has its own particular rate of expansion. The two metals that make up the strip are chosen so that the rates of expansion and contraction are different. When the strip is heated, one metal expands less than the other, so the strip curves, with the metal that expands more on the outside. This bending action is what moves the needle. Some newer cars, instead of sending the current directly to the gauge, use a microprocessor that reads the output of the resistor and communicates with the dashboard. These systems actually help improve the accuracy of the gauge. Let's take a look at one of these systems.carsmicroprocessor

Fuel GAUGE :- the gauge consists of two parts: The sensing unit The indicator The sensing unit usually uses a float connected to a potentiometer. typically printed ink design in a modern autmobile. As the tank empties, the float drops and slides a moving contact along the resistor, increasing its resistance.potentiometer In addition, when the resistance is at a certain point, it will also turn on a "low fuel" light on some vehicles. Meanwhile, the indicator unit (usually mounted on the dashboard) is measuring and displaying the amount of electrical current flowing through the sending unit. When the tank level is high and maximum current is flowing, the needle points to "F" indicating a full tank. When the tank is empty and the least current is flowing, the needle points to "E" indicating an empty tank.dashboard

The system can be fail-safe;if an electrical fault opens the electrical circuit causes the indicator to show the tank as being empty (which will provoke the driver to refill the tank (in theory)) rather than full (which would allow the driver to run out of fuel with no prior notification). Corrosion or wear of the potentiometer will provide erroneous readings of fuel level. However this system has a potential risk associated with it. An electric current is sent through the variable resistor to which a float is connected, so that the value of resistance depends on the fuel level. In most of automotive fuel gauges such resistors are on the inward side of gauge i.e. inside fuel tank. Sending current through such a resistor has fire hazard (and an explosion risk) associated with it. These resistance sensors are also showing an increased failure rate with the incremental additions of alcohol in automotive gasoline fuel. Alcohol increases the corrosion rate at the potentiometer, as it is capable of carrying current like water. Potentiometer applications for alcohol fuel use a pulse and hold methodology in that a periodic signal is sent to determine fuel level decreasing the corrosion potential. Therefore there is demand for another safer, non contact method for fuel level is desired.fail-safe

Working:- This circuit works on the principle that water conducts electricity. A wire connected to VCC and four other wires are dipped in tank at different levels namely quarter, half, three-fourth, full and their output are taken on pins P3.0, P3.1, P3.2, P3.3 via a transistor BC547. Port P2 is connected to data pins of LCD and P1.0, P1.1, P1.2 are respectively connected to RS, RW, and EN pins of LCD. Initially when the tank is empty LCD will show the message VACANT. As the tank starts filling up wire at different levels get some positive voltage, due to conducting nature of water. This voltage is then fed to their corresponding pins on controller. When level reaches to quarter level, LCD displays the message QUARTER. On further rise of level, HALF and 3/4 QUARTER are displayed on LCD. When tank gets full LCD shows the message FULL CLOSE TAP. A buzzer is also provided to produce a alert the user when the tank gets filled. This buzzer can be made off by pressing the switch connected between pin 15 of controller and VCC.

CIRCUIT DIAGRAM:-

COMPONENTS REQUIRED:- Preset A preset is a three legged electronic component which can be made to offer varying resistance in a circuit. The resistance is varied by adjusting the rotary control over it. The adjustment can be done by using a small screw driver. Transistor BC547 BC547 is an NPN bi-polar junction transistor. A transistor, stands for transfer of resistance, is commonly used to amplify current.

COMPONENTS REQUIRED:- Piezo Buzzer The piezo buzzer produces sound based on reverse of the piezoelectric effect. The generation of pressure variation or strain by the application of electric potential across a piezoelectric material is the underlying. AT89C51 Microcontroller AT89C51 is an 8-bit microcontroller and belongs to Atmel's 8051 family. ATMEL 89C51has 4KB of Flash programmable and erasable read only memory.

COMPONENTS REQUIRED:- LCD LCD (Liquid Crystal Display) screen is an electronic display module and find a wide range of applications. A 16x2 LCD display is very basic module and is very commonly used in various devices and circuits. These modules are preferred over seven segments.

Advantage :-  It is used in automobiles (cars,bikes).  It can also be used as a water level indicator.  The system allows the fuel load to be preselected.  This system can be more than 99% accurate.

Disadvantage :-  This system can be more than 99% accurate and remaining 1 % is not accurate this is the only disadvantage with the digital liquid level indicator.

APPLICATIONS :-  It is used in automobiles (cars,bikes).  It can also be used as a water level indicator.  large transport aircraft use a fuel gauge.aircraft