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LPG

 BASED

 SNIFFR

                               

 

 

 

 

 

 

Introduction

 

In this project we  will use LPG sniffer project. In this project we will make ROBOT to find out LPG gas. When it will founfd GAS it will give buzzer and will stop to indicate GAS found .Here in this project we show that how we detect a gas or any type of  gases and if we detect a gases then alarm is on and the same time lcd display shows the gas detection display. If the gas is detected then relay is off and break the supply of gas applied to the vehicle or we can control any type of electrical connection on or off by this relay operated logic.

 

Main part of this project is gas sensor.

Here we use TGS gas sensor. This sensor is a 6 pin sensor . Top and  bottom of the sensor is covered with 100 mesh stainless stell wire cloth. The heart of the sensor is the cylindrical form in the middle of the unit. The cylinder is a ceramic material with the SnO2 material deposited on its surface. The heater coil is located inside the ceramic cylinder. The heater has a resistance of 38 ohms.

 

Output of the gas sensor is connected the ic 555 as a monostable trigger ic. As the sensor is detect a gas then ic 555 activate automatically and then output of the ic 555 is connected to the microcontroller circuit.

 

In the microcontroller circuit we use ic 89s51 controller. Use of this is is to control the one or many relay logic and at the same time show the message on the lcd display. If no gas is detected then display shows a everything is ok . If the gas is detected then show a warning message on the screen and at the same time relay off the supply unit.

 

IN the  gas sensor interface we use gas  sensor as a input logic. We attach one ic 555 as  with this sensor . Here ic 555 work as a monostable timer.  Sensor output is connected to the  ic 555 pin no 2 via npn transistor. Pin no 2 is a negative trigger ic. When sensor activate then positive output is available and  this positive output  is converted into  negative with the help of the NPN transistor. Output of the NPN transistor is now connected to the  pin no 2 of the ic 555. Pinno 4 and 8 of the ic 555 is connected to the positive supply. Pin no 1 is connected to the ground pin. Pin no 7 is the output pin. Pin no 6 and 7 is the time constant pin. Pin no 6 and 7 provide a time constant option. When ic 555 works then  output is available on the pin no 3 . Now this output is switching by the further NPN transistor.One led is also connected to the  transistor circuit. Output of the npn transistor is available on the collector point. This output  from the collector of NPN is  now connected to the microcontroller pin no 1 which is port p1.0. Pin no 40 of the  controller is connected to the positive supply. We supply a 5 volt regulated power supply on this pin. For regulated power supply we use one step down transformer  . Step down transformer step down the voltage from 220 volt ac to 9 volt ac. This ac is converted into  dc with the help of the rectifier circuit. Here we use two diode as a  full wave rectifier. Output of the rectifier is now converted into 5 volt regulated supply with the help of 7805 regulator. IC 7805 regulator  provide a 5 volt constant  supply to pin no 40 of the ic. Pin no 20 is connected to the ground pin.  LCD is connected to the port 0. Here we use 2 by 16 lcd for display. 2 by 16 means  2 line and 16 character.

 

Two output is available from the controller from port P2. One output is buzzer and second output    is relay output. Buzzer is on when  circuit sense a gas and  relay  switch off the supply chain.

 

To control a relay we use two transistor circuit. Output from the controller is  drive the pnp transistor through  1 k ohm resistor. Collector of the pnp transistor is connected to the npn transistor through 1 k ohm resistor. Collector of the NPN transistor is connected to the  relay coil  directly. . Here relay is for the switching purpose only . As the  transistor is on  relay is on and relay break the contact of supply  chain.

 

WELCOME TO THE WORLD OF THE MICROCONTROLLERS.

 

Look around. Notice the smart “intelligent” systems? Be it the T.V, washing machines, video games, telephones, automobiles, aero planes, power systems, or any application having a LED or a LCD as a user interface, the control is likely to be in the hands of a micro controller!

Measure and control, that’s where the micro controller is at its best.

Micro controllers are here to stay. Going by the current trend, it is obvious that micro controllers will be playing bigger and bigger roles in the different activities of our lives.

So where does this scenario leave us? Think about it……

The world of Micro controllers

What is the primary difference between a microprocessor and a micro controller? Unlike the microprocessor, the micro controller can be considered to be a true “Computer on a chip”.

In addition to the various features like the ALU, PC, SP and registers found on a microprocessor, the micro controller also incorporates features like the ROM, RAM, Ports, timers, clock circuits, counters, reset functions etc.

While the microprocessor is more a general-purpose device, used for read, write and calculations on data, the micro controller, in addition to the above functions also controls the environment.

We have used a whole lot of technical terms already! Don’t get worried about the meanings at this point. We shall understand these terms as we proceed further

For now just be aware of the fact, that all these terms literally mean what they say.

Bits and Bytes

Before starting on the 8051, here is a quick run through on the bits and bytes. The basic unit of data for a computer is a bit. Four bits make a nibble. Eight bits or two nibbles make a byte. Sixteen bits or four nibbles or two bytes make a word.

1024 bytes make a kilobyte or 1KB, and 1024 KB make a Mega Byte or 1MB.

Thus when we talk of an 8-bit register, we mean the register is capable of holding data of 8 bits only.

The 8051

The 8051 developed and launched in the early 80`s, is one of the most popular micro controller in use today. It has a reasonably large amount of built in ROM and RAM. In addition it has the ability to access external memory.

The generic term `8x51` is used to define the device. The value of x defining the kind of ROM, i.e. x=0, indicates none, x=3, indicates mask ROM, x=7, indicates EPROM and x=9 indicates EEPROM or Flash.

A note on ROM

The early 8051, namely the 8031 was designed without any ROM. This device could run only with external memory connected to it. Subsequent developments lead to the development of the PROM or the programmable ROM. This type had the disadvantage of being highly unreliable.

The next in line, was the EPROM or Erasable Programmable ROM. These devices used ultraviolet light erasable memory cells. Thus a program could be loaded, tested and erased using ultra violet rays. A new program could then be loaded again.

An improved EPROM was the EEPROM or the electrically erasable PROM. This does not require ultra violet rays, and memory can be cleared using circuits within the chip itself.

Finally there is the FLASH, which is an improvement over the EEPROM. While the terms EEPROM and flash are sometimes used interchangeably,

MPONE

COMPONENTS USED:

STEP DOWN TRANSFORMER        220 TO 9 VOLT AC

DIODE    IN 4007(2)

 CAPACITOR  ,1000 MFD (1), 33 MFD (1), 27 PF (2).

NPN TRANSISTOR BC 548(4)

PNP TRANSISTOR BC 558(2)

RESISTOR  100 K (2), 1 K (4), 470 OHM (1), 10 K (3)

PULL UP RESISITOR ARRAY. 10 K (1)

VARIABLE RESISTOR 4.7 K (1)

L.E.D (3)

RELAY 12 VOLT

BUZZER DC

IC89S51

PC817- 4 NOS

TYRES-  2NOS

PLY BOARD

SOLDERING IRON

SOLDERING WIRE

MULTIMETER

IC 555 TIMER

104 PG ACPACIOTR

10K REISTOR- 10 NOS

4.7 K- 2 NOS

Ic PROGRAMMER

KEIL SOFTWARE

CONNECTING WIRES

CASTEL WHEEL

DC GEARED MOTORS- 2NOS

LPG GAS SENSOR- - 1 NOS

 

 

 

 

 

 

 

Bilbliography

 

 

Sensor detail:

www.atmel.com

www.projectiseas.com

www.ludhianaprojects.com/projects.htm

http://www.winsensor.com/english/products.asp

http://www.futurlec.com/Gas_Sensors.shtml