APROJECT REPORT

ON

“PATH FOLLOWER AND OBSTACLE DETECTOR”

SUBMITTED TO

UTTAR PRADESH TECHNICAL UNIVERSITY, LUCKNOWIN PARTIAL FULFILLMENT OF THE REQUIREMENT OF THE AWARD

OFTHE DEGREE OF

BACHELOR OF TECHNOLOGYIN

ELECTRONICS & INSTRUMENTATION ENGINEERING2007-2008

SUBMITTED BY

HANEEF KHAN 0406432027 RAJESH KUMAR SINGH 0406432043 DEVENDRA GAUTAM 0406432022

SHIVAM SRIVATAVA 0406432051

UNDER THE GUIDANCE OF

Ms. RANJEETA ROYLECTURER, DEPT. OF ELECTRONICS &. INSTRUMENTATION

HCST, MATHURA, (UP)

HINDUSTAN COLLEGE OF SCIENCE & TECHNOLOGYELECTRONICS & INSTRUMENTATION ENGINEERING DEPARTMENT

FARAH (MATHURA)

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CONTENT

TOPIC ………………………………….………………………….PAGE No.

1. INTRODUCTION......................................................................................10

2. CIRCUIT DESCRIPTION………………………………………….......

3. SOFTWARE DESCRIPTION……………………………………………13

4. COMPONENTS USED & DESCRIPTION……………………………..14

(i) ATMEL 89C2051 MICROCONTROLLER………………..

(ii) FEATURES & PIN DESCRIPTION………………………...

(iii) INTERFACING LCD……………………………………….28

(iv) RELAY……………………………………………………….36

(v) DIODE………………………………………………………..41

5. PROGRAMMING………………………………………………………44

6. LPG GAS SENSOR…………………………………………………….52

(i)INTRODUCTION……………………………………………53

(i)COMPONENTS USED……………………………………….53

(ii)WORKING…………………………………………………..54

(iii)CIRCUIT DIAGRAM………………………………...........55

(iv)PRECAUTIONS…………………………………………….56

7. FIRE ALARM………………………………………………....58

(i)INTRODUCTION………………………………………….59

(ii) COMPONENTS USED…………………………………60

(ii)WORKING………………………………………………61

(iii)CIRCUIT DIAGRAM………………………………......63

(iv)PRECAUTIONS…………………………………………64

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8. WATER LEVEL INDICATOR…………………………….66

(i)INTRODUCTION………………………………………..66

(ii)COMPONENTS USED………………………………….67

(iii)WORKING………………………………………………68

(iv)CIRCUIT DIAGRAM……………………………………70

(v)PRECAUTIONS…………………………………………..71

9.REFERENCE……………………………………………………..73

10.IMAGE GALLERY…………………………………………….74

ACKNOWLEDGEMENTS

We feel extremely satisfied presenting this project report entitled:-

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“ PATH FOLLOWER AND OBSTACLE DETECTOR ”

First and foremost we extend a very deep sense of gratitude to our project guide Ms. RAJEETA ROY for her valuable guidance and encouragement at starting stage of our project.

We would also like to extend our heart-felt thanks to Mr. Santosh Kumar Agrahari who gave us guidance, inspiration and suggestions regarding our project and helped us in our venture for the starting and tend towards the successful completion of our project.

We are very thankful to Mr. Mukund Lal (H.O.D., Elect. & instrum. Dept.) for motivating us towards our project and arranging such Laboratories and for giving us excellent knowledgeable guides for successful completion of our project.

Once again, our sincere thanks to all those who are directly or indirectly associated with our project.

HANEEF KHAN

RAJESH KUMAR SINGH

DEVENDRA GAUTAM

SHIVAM SRIVASTAV

HINDUSTAN COLLEGE OF SCIENCE AND TECHENOLOGYELECTRONICS & INSTRUMENTATION ENGINEERING DEPART MENT

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DEPARTMENT OF

ELECTRONICS & INSTRUMENTATION ENGINEERING

CERTIFICATE

THIS IS TO CERTIFY THAT THE PROJECT ENTITLED

“PATH FOLLOWER AND OBSTACLE DETECTOR”

IS

SUBMITTED BY

HANEEF KHAN 0406432027 RAJESH KUMAR SINGH 0406432043

DEVENDRA GAUTAM 0406432022SHIVAM SRIVASTAV 0406432051

IN PARTIAL FULFILLMENT FOR THE AWARD OF THE DEGREE IN ELECTRONICS & INSTRUMENTATION ENGG. OF UTTAR PRADESH TECHNICAL UNIVERSITY, LUCKNOW IN THE RECORD OF THEIR OWN WORK DONE UNDER MY SUPERVISION AND GUIDENCE DURING SESSION OF 2007-08.

GUIDE: CORDINATOR: HEAD: Ms.RAJEETAROY Mr.SANTOSH KUMAR Mr. MUKUND LAL AGRAHARI

(Elect. & Instrumentation Dep

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ABSTRACT

Our project is titled as”Electronic Security of House” embedded with a number of

features. The project aims at:

Providing a locking mechanism that is completely digitized and is activated

through a numeric code.

This lock prevents unauthorized access over devices that need security. The lock

can be installed over any device or place that requires to be accessed by limited

persons.

The lock works in the same way as a code based suitcase which opens only

when the correct code is entered.

A Fire Alarm system which will detect the fire and buzzer will be on.

Water level indicator which will indicate the different level of water through LED’s

and will give blow a buzzer when tank is full.

LPG gas detector which detect LPG gas through a gas sensor MQ5 ,when a gas

is leak.

For the accomplishment of these features, we have used microcontroller, digital and

timer ICs, 20-pin DIP switches, relays, transistors, transformer, LEDs, LCD, etc. This

simple code lock project is based on a 20-pin ATMEL microcontroller AT89C2051. It

employs a 4-digit sequential code with time-out security feature. In addition to the

microcontroller, the circuit uses a single additional IC (CD4050) and a transistor to drive

a relay. Although the project uses a liquid-crystal display (LCD), it is useful for design

and developmental purpose only and is not really an essential part of the circuit.

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Code is written in assembly language using BASCOM-51. It controls the peripheral

device LCD. The BOSCOM compiler /IDE can be used to generate a hex file, which

should be ‘burnt’ into the chip using any universal programmer. The best thing of our

project is that we have used minimum resources so we can add more features in future.

So there is scope of modification in coming time.

A very special IC is used for regulating voltage. It is a 3-terminal type constant voltage

regulator. It provides desired current and voltage value to motors to drive them.

The digitized locking system finds its applications in various spheres of security at

individual as well as corporate level.

It is an excellent product for indoor security and can be installed at home, offices,

banks, schools and almost all places where security is required. Another important field

of application is at the component level where this device can be used to provide

restricted access to devices.

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INTRODUCTION

Our project is titled as “Digitized Programmable Code-Based Locking System”. Our

project is a conglomeration of electronics, hardware (mechanical part) and software.

Code locks can be constructed using digital and timer ICs employing pushbuttons or

keypads for entering the code for authentication and operation of the code lock.

However, such circuits would require a large number of ICs.

On the other hand, a microcontroller-based code lock will require very few peripheral

components. With the cost of microcontrollers now dropping to be equivalent cost of

approximately four digital ICs, it makes sense to design simple logic circuits using

microcontrollers and free version of programming language code length is normally

limited to around 2 kB, but that is adequate for small projects like this one.

This simple code lock project is based on a 20-pin ATMEL microcontroller AT89C2051.

It employs a 4-digit sequential code with time-out security feature. In addition to the

microcontroller, the circuit uses a single additional IC (CD4050) and a transistor to drive

a relay. Although the project uses a liquid-crystal display (LCD), it is useful for design

and developmental purpose only and is not really an essential part of the circuit. The

same can be removed from the circuit without any change in the software.

As regards LCD modules, these are available in 14-or 16-pin packages. The 16-pin

variety has an additional back-light option. Popular brands available in India are

Lampex, Hantronix and Hitachi. Most other models also have the same pin

configuration. The model used in this project is Lampex LM16200 16-character2-line

alphanumeric dot-matrix display with back-light option. However, you may also use any

other branded / unbranded LCD for the purpose.

\

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CIRCUIT DESCRIPTION:-

As already mentioned, the project makes use of ATMEL AT89C2051 microcontroller,

in 20-pin DIP package, which supports 2 kB of flash-based program memory. A 6MHz

crystal is used for providing the clock. Port-1 of Microcontroller is used to drive the LCD

in 4-bit mode with 10-kilo-ohm pull-up resistors. The 10- kilo-ohm potentiometer controls

the contrast of the LCD panel. It works better when its wiper is nearer to ground

potential. Timer 0 of 89C2051 is used as an internal counter that increments a variable

every second. This variable is used in the project to time out the delay for entering the

code.After initialization, the software switches on ‘Read’ LED and waits for a 4-digit

code to be entered. The valid code for this project is ‘1324’. The code is entered using

the seven input switches that are connected to port-3. Port-3 does not have the bit

‘P3.6’ and hence the same is ignored by the software. Two LEDs at port-1 are

interfaced to P1.0 and P1.1 pins to provide ‘Ready’ and ‘Relay On’ indication via

respective LEDs.The P1.1 line is also interfaced to relay driver transistor T1 through a

buffer to switch on a 12V relay, which can activate an electrically operated lock.

Timer 0 is started on the first key-stroke to validate the remaining three digits, provided

these digits are entered within five seconds. If not, the software loops back to the initial

state. After three unsuccessful attempts, the circuit will wait for about 10 seconds

(before accepting the next keystroke) to avoid unwanted tampering attempts. All these

timings can be changed through the software program to suit your specific

requirements.

A conventional regulated power supply. A conventional regulated power supply circuit

employing a step-down transformer followed by bridge rectifier, smoothing capacitor

and 5V regulator is used to meet the supply requirement for the code lock circuit shown

in Fig.An actual-size PCB layout for the code-lock including the power supply is shown

in Fig.3 and its component layout in Fig.4.

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Fig. : Actual-size, single-side PCB of microcontroller-based code lock

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SOFTWARE

SOFTWARE DESCRIPTION:-

The software is written using BASCOM-51. Although the program is self-explanatory,

but needs awareness of BASCOM51 compiler directives and syntax of statements,

which are available with in the help menu of BASCOM compiler. BASCOM contains a

lot of statements to control various a lot of statements to control various peripherals

including the LCD.

The BOSCOM compiler /IDE can be used to generate a hex file, which should be ‘burnt’

into the chip using any universal programmer. The hex code of the program is only 1.5k

long, while AT89C2051 microcontroller can take up to 2k of code. This program may be

modified to suit your specific requirement.

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COMPONENT LIST

Semiconductors:-

IC1........................................................AT89C2051 Microcontroller

IC2........................................................CD 4050 non-inverting buffer

IC3........................................................7805 +5V regulator

T1.........................................................2N2222 npn transistor

D1-D5...................................................IN4007 rectifier diode

LED1-LED3..........................................5mm LED

Resistors (all ¼-watt, 5% carbon):-

R1, R2, R4............................................220-ohm

R3.........................................................150-ohm

R5.........................................................10-kilo-ohm

RNW1, RNW2......................................10 –kilo-ohm resistor network

VR1......................................................10-kilo-ohm preset

Capacitors:-

C1.........................................................10F, 16V electrolytic

C2, C3..................................................22pF ceramic disk

C4, C6..................................................0.1F ceramic disk

C5.........................................................1000 F, 25V electrolytic

Miscellaneous:-

X...........................................................6MHz crystal

RL1.......................................................5V, 100-ohm, IC/O relay

S1-S8...................................................Push-to-on switch

S9.........................................................On / off switch

X1.........................................................230V AC primary to 9V,

250mA secondary transformer

.............................................................16 character2-line LCD

(male-53 pins used)

.............................................................Bergstick connector

(female-36 pins used)

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COMPONENT

DESCRIPTION

ATMEL AT89C251 microcontroller:-

1. Features:-

Compatible with MCS-51 Products

2K Bytes of In-System Reprogrammable Flash Memory

Endurance: 1,000 Write/Erase Cycles

Fully Static Operation: 0 Hz to 24 MHz

Three Level program Memory Lock

128 x 8-bit Internal RAM

32- Programmable I/O Lines

Two 16-bit Timer/Counters

Six Interrupt Sources

Programmable Serial Channel

Low Power Idle and Power-down Modes

2. Description :-

The AT89C2051 is a low-voltage, high-performance CMOS 8-bit microcomputer with 2K

bytes of Flash programmable and erasable read-only memory (PEROM). The device is

manufactured using Atmel’s high-density nonvolatile memory technology and is

compatible with the industry-standard MCS-51 instruction set. By combining a versatile

8-bit CPU with Flash on a monolithic chip, the Atmel AT89C2051 is a power-ful

microcomputer which provides a highly-flexible and cost-effective solution to many

embedded control applications. The AT89C2051 provides the following standard

features: 2K bytes of Flash, 128 bytes of RAM, 15 I/O lines, two 16-bit timer/counters, a

five vector two-level interrupt architecture, a full duplex serial port, a precision analog

comparator, on-chip oscillator and clock circuitry. In addition, the AT89C2051 is

designed with static logic for opera-tion down to zero frequency and supports two

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software selectable power saving modes. The Idle Mode stops the CPU while allowing

the RAM, timer/counters, serial port and interrupt system to continue functioning. The

power-down mode saves the RAM contents but freezes the oscillator disabling all other

chip functions until the next hardware reset.

3. Pin Configuration:-

3. Pin Description:-

VCC

Supply voltage.

GND

Ground.

Port 1

The Port 1 is an 8-bit bi-directional I/O port. Port pins P1.2 to P1.7 provide internal pull-

ups. P1.0 and P1.1 require external pull-ups. P1.0 and P1.1 also serve as the positive

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input (AIN0) and the negative input (AIN1), respectively, of the on-chip precision analog

comparator. The Port 1 out-put buffers can sink 20 mA and can drive LED displays

directly. When 1s are written to Port 1 pins, they can be used as inputs. When pins P1.2

to P1.7 are used as inputs and are externally pulled low, they will source current (IIL)

because of the internal pull-ups. Port 1 also receives code data during Flash

programming and verification.

Port 3

Port 3 pins P3.0 to P3.5, P3.7 are seven bi-directional I/O pins with internal pull-ups.

P3.6 is hard-wired as an input to the output of the on-chip comparator and is not

accessible as a gen-eral-purpose I/O pin. The Port 3 output buffers can sink 20 mA.

When 1s are written to Port 3 pins they are pulled high by the internal pull-ups and can

be used as inputs. As inputs, Port 3 pins that are externally being pulled low will source

current (IIL) because of the pull-ups. Port 3 also serves the functions of various special

features of the AT89C2051 as listed below: Port 3 also receives some control signals

for Flash programming and verification.

RST

Reset input. All I/O pins are reset to 1s as soon as RST goes high. Holding the RST pin

high for two machine cycles while the oscillator is running resets the device. Each

machine cycle takes 12 oscillator or clock cycles.

XTAL1

Input to the inverting oscillator amplifier and input to the internal clock operating circuit.

Port Pin Alternate Functions P3.0 RXD (serial input port) P3.1 TXD (serial output

port) P3.2

INT0 (external interrupt 0) P3.3 INT1 (external interrupt 1) P3.4 T0 (timer 0 external

input) P3.5 T1 (timer 1 external input).

XTAL2

Output from the inverting oscillator amplifier.

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4. Oscillator Characteristics:-

The XTAL1 and XTAL2 are the input and output, respectively, of an inverting amplifier

which can be configured for use as an on-chip oscillator, as shown in Figure 5-1. Either

a quartz crystal or ceramic resonator may be used. To drive the device from an external

clock source, XTAL2 should be left unconnected while XTAL1 is driven as shown in

Figure 5-2. There are no require-ments on the duty cycle of the external clock signal,

since the input to the internal clocking circuitry is through a divide-by-two flip-flop, but

minimum and maximum voltage high and low time specifications must be observed.

Figure 5-1. Oscillator Connections

Note: C1, C2 = 30 pF ± 10 pF for Crystals = 40 pF ± 10 pF for Ceramic Resonators

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6. Special Function Registers:-

A map of the on-chip memory area called the Special Function Register (SFR) space is

shown in the table below. Note that not all of the addresses are occupied, and

unoccupied addresses may not be imple-mented on the chip. Read accesses to these

addresses will in general return random data, and write accesses will have an

indeterminate effect. User software should not write 1s to these unlisted locations, since

they may be used in future products to invoke new features. In that case, the reset or

inactive values of the new bits will always be 0.

7. Restrictions on Certain Instructions :-

The AT89C2051 and is an economical and cost-effective member of Atmel’s growing

family of microcontrollers. It contains 2K bytes of Flash program memory. It is fully

compatible with the MCS-51 architecture, and can be programmed using the MCS-51

instruction set. However, there are a few considerations one must keep in mind when

utilizing certain instructions to pro-gram this device. All the instructions related to

jumping or branching should be restricted such that the destination address falls within

the physical program memory space of the device, which is 2K for the AT89C2051. This

should be the responsibility of the software programmer. For example, LJMP 7E0H

would be a valid instruction for the AT89C2051 (with 2K of memory), whereas LJMP

900H would not.

7.1 Branching Instructions:-

LCALL, LJMP, ACALL, AJMP, SJMP, JMP @A+DPTR

– These unconditional branching instructions will execute correctly as long as the

programmer keeps in mind that the destination branching address must fall within the

physical boundaries of the program memory size (loca-tions 00H to 7FFH for the

89C2051). Violating the physical space limits may cause unknown program behavior.

CJNE [...], DJNZ [...], JB, JNB, JC, JNC, JBC, JZ, JNZ – With these conditional

branching instructions the same rule above applies. Again, violating the memory

boundaries may cause erratic execution. For applications involving interrupts the normal

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interrupt service routine address locations of the 80C51 family architecture have been

preserved.

7.2 MOVX-related Instructions, Data Memory:-

The AT89C2051 contains 128 bytes of internal data memory. Thus, in the AT89C2051

the stack depth is limited to 128 bytes, the amount of available RAM. External DATA

memory access is not supported in this device, nor is external PROGRAM memory

execution. Therefore, no MOVX [...] instructions should be included in the program. A

typical 80C51 assembler will still assemble instructions, even if they are written in

violation of the restrictions mentioned above. It is the responsibility of the controller user

to know the physi-cal features and limitations of the device being used and adjust the

instructions used correspondingly.

8. Idle Mode:-

In idle mode, the CPU puts itself to sleep while all the on-chip peripherals remain active.

The mode is invoked by software. The content of the on-chip RAM and all the special

functions regis-ters remain unchanged during this mode. The idle mode can be

terminated by any enabled interrupt or by a hardware reset. The P1.0 and P1.1 should

be set to “0” if no external pull-ups are used, or set to “1” if external pull-ups are

used. It should be noted that when idle is terminated by a hardware reset, the device

normally resumes program execution, from where it left off, up to two machine cycles

before the internal reset algorithm takes control. On-chip hardware inhibits access to

internal RAM in this event, but access to the port pins is not inhibited. To eliminate the

possibility of an unexpected write to a port pin when Idle is terminated by reset, the

instruction following the one that invokes Idle should not be one that writes to a port pin

or to external memory.

9. Power-down Mode:-

In the power-down mode the oscillator is stopped, and the instruction that invokes

power-down is the last instruction executed. The on-chip RAM and Special Function

Registers retain their values until the power-down mode is terminated. The only exit

from power-down is a hardware reset. Reset redefines the SFRs but does not change

the on-chip RAM. The reset should not be activated before VCC is restored to its normal

operating level and must be held active long enough to allow the oscillator to restart and

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stabilize. The P1.0 and P1.1 should be set to “0” if no external pull-ups are used,

or set to “1” if external pull-ups are used.

10. Programming the Flash:-

The AT89C2051 is shipped with the 2K bytes of on-chip PEROM code memory array in

the erased state (i.e., contents = FFH) and ready to be programmed. The code memory

array is pro-grammed one byte at a time. Once the array is programmed, to re-program

any non-blank byte, the entire memory array needs to be erased electrically.

Internal Address Counter: The AT89C2051 contains an internal PEROM address

counter which is always reset to 000H on the rising edge of RST and is advanced by

applying a positive going pulse to pin XTAL1.

Programming Algorithm:

To program the AT89C2051, the following sequence is recommended.

1. Power-up sequence: Apply power between VCC and GND pins Set RST and XTAL1

to GND

2. Set pin RST to “H” Set pin P3.2 to “H”

3. Apply the appropriate combination of “H” or “L” logic levels to pins P3.3, P3.4, P3.5,

P3.7 to select one of the programming operations shown in the PEROM Programming

Modes table.To Program and Verify the Array:

4. Apply data for Code byte at location 000H to P1.0 to P1.7.

5. Raise RST to 12V to enable programming.

6. Pulse P3.2 once to program a byte in the PEROM array or the lock bits. The byte-

write cycle is self-timed and typically takes 1.2 ms.

7. To verify the programmed data, lower RST from 12V to logic “H” level and set pins

P3.3 to P3.7 to the appropriate levels. Output data can be read at the port P1 pins.

8. To program a byte at the next address location, pulse XTAL1 pin once to advance the

internal address counter. Apply new data to the port P1 pins.

9. Repeat steps 6 through 8, changing data and advancing the address counter for the

entire 2K bytes array or until the end of the object file is reached.

10. Power-off sequence: set XTAL1 to “L” set RST to “L” Turn VCC power off

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Data Polling: The AT89C2051 features Data Polling to indicate the end of a write cycle.

During a write cycle, an attempted read of the last byte written will result in the

complement of the writ-ten data on P1.7. Once the write cycle has been completed, true

data is valid on all outputs, and the next cycle may begin. Data Polling may begin any

time after a write cycle has been initiated.

Ready/Busy : The Progress of byte programming can also be monitored by the

RDY/BSY output signal. Pin P3.1 is pulled low after P3.2 goes high during programming

to indicate BUSY. P3.1 is pulled High again when programming is done to indicate

READY.

Program Verify: If lock bits LB1 and LB2 have not been programmed code data can be

read back via the data lines for verification:

1. Reset the internal address counter to 000H by bringing RST from “L” to “H”.

2. Apply the appropriate control signals for Read Code data and read the output data at

the port P1 pins.

3. Pulse pin XTAL1 once to advance the internal address counter.

4. Read the next code data byte at the port P1 pins.

5. Repeat steps 3 and 4 until the entire array is read. The lock bits cannot be verified

directly. Verification of the lock bits is achieved by observing that their features are

enabled.

Chip Erase: The entire PEROM array (2K bytes) and the two Lock Bits are erased

electrically by using the proper combination of control signals and by holding P3.2 low

for 10 ms. The code array is written with all “1”s in the Chip Erase operation and must

be executed before any non-blank memory byte can be re-programmed.

Reading the Signature Bytes: The signature bytes are read by the same procedure as

a nor-mal verification of locations 000H, 001H, and 002H, except that P3.5 and P3.7

must be pulled to a logic low. The values returned are as follows.

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(000H) = 1EH indicates manufactured by Atmel

(001H) = 21H indicates 89C2051

11. Programming Interface:-

Every code byte in the Flash array can be written and the entire array can be erased by

using the appropriate combination of control signals. The write operation cycle is self-

timed and once initiated, will automatically time itself to completion. Most major

worldwide programming vendors offer support for the Atmel AT89 microcontroller

series. Please contact your local programming vendor for the appropriate software

revision. Notes: 1. The internal PEROM address counter is reset to 000H on the rising

edge of RST and is advanced by a positive pulse at XTAL1 pin. 2. Chip Erase requires

a 10 ms PROG pulse. 3. P3.1 is pulled Low during programming to indicate RDY/BSY.

Programming:

Several C compilers are available for the 8051, most of which feature extensions that

allow the programmer to specify where each variable should be stored in its six types of

memory, and provide access to 8051 specific hardware features such as the multiple

register banks and bit manipulation instructions. Other high level languages such as

Forth, BASIC, Pascal, PL/M and Modula 2 are available for the 8051, but they are less

widely used than C and assembly.

INTERFACING LED TO 8051:-

Liquid Crystal Display also called as LCD is very helpful in providing user interface as

well as for debugging purpose. The most common type of LCD controller is HITACHI

44780 which provides a simple interface between the controller & an LCD. These LCD's

are very simple to interface with the controller as well as are cost effective.

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The most commonly used ALPHANUMERIC displays are 1x16 (Single Line & 16

characters), 2x16 (Double Line & 16 character per line) & 4x20 ( four lines & Twenty

characters per line).

The LCD requires 3 control lines (RS, R/W & EN) & 8 (or 4) data lines. The number on

data lines depends on the mode of opertaion. If operated in 8-bit mode then 8 data lines

+ 3 control lines i.e. total 11 lines are required. And if operated in 4-bit mode then 4 data

lines + 3 control lines i.e. 7 lines are required. How do we decide which mode to use?

Its simple if you have sufficient data lines you can go for 8 bit mode & if there is a time

constrain i.e. display should be faster then we have to use 8-bit mode because basically

4-bit mode takes twice as more time as compared to 8-bit mode

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When RS is low (0), the data is to be treated as a command. When RS is high (1), the

data being sent is considered as text data which sould be displayed on the screen.

When R/W is low (0), the information on the data bus is being written to the LCD. When

RW is high (1), the program is effectively reading from the LCD. Most of the times there

is no need to read from the LCD so this line can directly be connected to Gnd thus

saving one controller line.The EN pin is used to latch the data present on the data pins.

A HIGH - LOW signal is required to latch the data. The LCD interprets and executes our

command at the instant the EN line is brought low. If you never bring EN low, your

instruction will never be executed.

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Pin Symbol Function

1 Vss Ground

2 Vdd Supply

Voltage

3 Vo Contrast

Setting

4 RS Register

Select

5 R/W Read/Write

Select

6 En Chip Enable

Signal

7-

14

DB0-

DB7 Data Lines

15 A/Vee Gnd for the

backlight

16 K Vcc for

backlight

For Contrast setting a 10K pot should be used as shown in the figure.

Display Data Ram (DDRAM) stores the display data. So when we have to display a

character on LCD we basically write it into DDRAM. For a 2x16 LCD the DDRAM

address for first line is from 80h to 8fh & for second line is 0c0h to 0cfh. So if we want to

display 'H' on the 7th postion of the first line then we will write it at location 87.

IC 7805:-

THE ADAPTING 3-TERMINAL VOLTAGE REGULATORS FOR CONSTANT HIGH

VOLTAGE POWER SUPPLIES

One can get a constant high-voltage power supply using inexpensive 3-terminal

voltage regulators through some simple techniques described below. Depending upon

the current requirement, a reasonable load regulation can be achieved. Line regulation

in all cases is equal to that of the voltage regulator used.

Though high voltage can be obtained with suitable voltage boost circuitry using

ICs like LM 723, some advantages of the circuits presented below are: simplicity, low

cost, and practically reasonable regulation characteristics. For currents of the order of

1A or less, only one zener and some resistors and capacitors are needed. For higher

currents, one pass transistor such as ECP055 is needed.

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Before developing the final circuits, let us first understand the 3-terminal type

constant voltage regulators. Let us see the schematic in Fig. where 78XX is a 3-terminal

voltage regulator.

Schematic for obtaining low-voltage regulated output using 3-terminal voltage

regulators.

(27)

LIQUID CRYSTAL DISPLAYS (LCD)

Certain organic large size molecule types of liquids possess properties, which cause

them to interfere with light passage in them. One type, called the twisted nematic type,

is becoming more useful in today’s LCDs. In this, the liquid crystals have thread-like

shapes: the units join head to tail for million molecules to form lengthy chains. Moreover

each plane is twisted a few degrees from the next. Some of the recent chemicals of this

variety are made of pyrimidines, phenyl cyclohexanes, bicyclohexane and 4-(4’ methoxy

benzylidine) -n-butylaniline. They exhibit a crystalline structure even in liquid form at

ordinary temperatures.

The property of the liquid is anisotropic in the two perpendicular directions. The cell

thickness is so designed that there is a 900 turn of the molecules between the top and

the bottom faces. The twisted nematic has the property that twists light, which passes

through it. Polaroid filters are fitted above and below the cell so that light is polarized as

it enters, and is twisted through 900, exiting through a filter kept at 900 to the one at top.

The light is then reflected via a mirror at the back and returns via the same pathway.

It has just a 12 m thin layer of liquid between two or more sheets of glass cum

polarizer filters. One glass plate has the 7 segment electrodes etched on it and a

conductive coating of tin oxide or Tin cum Indium oxide. The other plate has the

common electrode. The conductive coat is treated further for good surface contact to

liquid. The cell when assembled appears as clear glass: the segments are not visible.

When a voltage is applied between the plates, the molecules move with the dipoles

aligned in the cell axis. Thus those regions under the segments, which have the electric

field, have a contrasty appearance when viewed in light, while other unexcite segments

are invisible.The voltage needed is preferable 2-20 V A.C. The cathode (or front plane)

voltage input to the LCD goes through an ‘analog switch’ that is on at any time so that

a.c. voltage is applied to the appropriate segment. The anode (back plane) receives the

a.c. supply. The display driving switches are from a set of MOSFET switches, which

also form part of Integrated circuit. For eg. C 1200 clock LSI I.C. chip from Computer

Syst. Inc, USA, is a digital clock chip with the LCD display driver. Turn on time for the

(28)

LCD displays vary form 0.2-100 millisecs, depending on voltage applied. Turn of time is

30-100ms. So these displays are not suitable for very fast changing numbers. The

power consumption is 1to 10 micro watt/cm2. The voltage threshold for watch type LCD

display is 1 to 2V. The operating a.c. frequency is 50-100 KHz.

In another method dc pulses of identical amplitude are used: One pulse to the

back electrode and another to the display segment via and exclusive OR gate. In the

OFF state, the pulses are in-phase; in the ON-state, they are out of phase. The

frequency is 30-32 Hz. The power consumption for a LCD watch is roughly 45 W,

which is 1/1000th of that for LED displays.

(29)

MAKING PRINTED CIRCUIT BOARD (P.C.B.)

INTRODUCTION--

Making a Printed Circuit Board is the first step towards building electronic equipment by

any electronic industry. A number of methods are available for making P.C.B., the

simplest method is of drawing pattern on a copper clad board with acid resistant

(etchants) ink or paint or simple nail polish on a copper clad board and do the etching

process for dissolving the rest of copper pattern in acid liquid.

MATERIAL REQUIRED

The apparatus needs for making a P.C.B. is :-

* Copper Clad Sheet

* Nail Polish or Paint

* Ferric Chloride Powder. (Fecl)

* Plastic Tray

* Tap Water etc.

PROCEDURE

The first and foremost in the process is to clean all dirt from copper sheet with say spirit

or trichloro ethylene to remove traces grease or oil etc. and then wash the board under

running tap water. Dry the surface with forced warm air or just leave the board to dry

naturally for some time.

Making of the P.C.B. drawing involves some preliminary consideration such as

thickness of lines/ holes according to the components. Now draw the sketch of P.C.B.

design (tracks, rows, square) as per circuit diagram with the help of nail polish or

enamel paint or any other acid resistant liquid. Dry the point surface in open air, when it

is completely dried, the marked holes in P.C.B. may be drilled using 1Mm drill bits. In

(30)

case there is any shorting of lines due to spilling of paint, these may be removed by

scraping with a blade or a knife, after the paint has dried.

After drying, 22-30 grams of ferric chloride in 75 ml of water may be heated to about 60

degree and poured over the P.C.B. , placed with its copper side upwards in a plastic

tray of about 15*20 cm. Stirring the solution helps speedy etching. The dissolution of

unwanted copper would take about 45 minutes. If etching takes longer, the solution may

be heated again and the process repeated. The paint on the pattern can be removed

P.C.B. may then be washed and dried. Put a coat of varnish to retain the shine. Your

P.C.B. is ready.

REACTION

Fecl3 + Cu ----- CuCl3 + Fe

Fecl3 + 3H2O --------- Fe (OH)3 + 3HCL

PRECAUTION

1. Add Ferric Chloride (Fecl3) carefully, without any splashing. Fecl3 is irritating to

the skin and will stain the clothes.

2. Place the board in solution with copper side up.

3. Try not to breathe the vapours. Stir the solution by giving see-saw motion to the

dish and solution in it.

4. Occasionally warm if the solution over a heater-not to boiling. After some time

the unshaded parts change their colour continue to etch. Gradually the base

material will become visible. Etch for two minutes more to get a neat pattern.

5. Don't throw away the remaining Fecl3 solution. It can be used again for next

Printed Circuit Board P.C.B.

USES

(31)

Printed Circuit Board are used for housing components to make a circuit for

compactness, simplicity of servicing and case of interconnection. Thus we can define

the P.C.B. as : Prinked Circuit Boards is actually a sheet of bakelite (an insulating

material) on the one side of which copper patterns are made with holes and from

another side, leads of electronic components are inserted in the proper holes and

soldered to the copper points on the back. Thus leads of electronic components

terminals are joined to make electronic circuit.

In the boards copper cladding is done by pasting thin copper foil on the boards during

curing. The copper on the board is about 2 mm thick and weights an ounce per square

foot. The process of making a Printed Circuit for any application has the following steps

(opted professionally):

* Preparing the layout of the track.

* Transferring this layout photographically M the copper.

* Removing the copper in places which are not needed, by the process of etching

(chemical process)

* Drilling holes for components mounting.

(32)

PRINTED CIRCUIT BOARD

Printed circuit boards are used for housing components to make a circuit, for

comactness, simplicity of servicing and ease of interconnection. Single sided, double

sided and double sided with plated-through-hold (PYH) types of p.c boards are common

today.Boards are of two types of material (1) phenolic paper based material (2) Glass

epoxy material. Both materials are available as laminate sheets with copper cladding.

Printed circuit boards have a copper cladding on one or both sides. In both boards,

pasting thin copper foil on the board during curing does this. Boards are prepared in

sizes of 1 to 5 metre wide and upto 2 metres long. The thickness of the boards is 1.42

to 1.8mm. The copper on the boards is about 0.2 thick and weighs and ounce per

square foot.

(33)

TRANSFORMER:-

PRINCIPLE OF THE TRANSFORMER:-

Two coils are wound over a Core such that they are magnetically coupled. The

two coils are known as the primary and secondary windings.

In a Transformer, an iron core is used. The coupling between the

coils is source of making a path for the magnetic flux to link both the coils. A core as in

fig.2 is used and the coils are wound on the limbs of the core. Because of high

permeability of iron, the flux path for the flux is only in the iron and hence the flux links

both windings. Hence there is very little ‘leakage flux’. This term leakage flux denotes

the part of the flux, which does not link both the coils, i.e., when coupling is not perfect.

In the high frequency transformers, ferrite core is used. The transformers may be step-

up, step-down, frequency matching, sound output, amplifier driver etc. The basic

principles of all the transformers are same.

(34)

MINIATURE TRANSFORMER

CONVENTIONAL POWER TRANSFORMER

CRYSTAL OSCILLATORS:-

What are crystal oscillators?

Crystal oscillators are oscillators where the primary frequency determining element is a

quartz crystal. Because of the inherent characteristics of the quartz crystal the crystal

oscillator may be held to extreme accuracy of frequency stability. Temperature

compensation may be applied to crystal oscillators to improve thermal stability of the

crystal oscillator.

Crystal oscillators are usually, fixed frequency oscillators where stability and accuracy

are the primary considerations. For example it is almost impossible to design a stable

and accurate LC oscillator for the upper HF and higher frequencies without resorting to

some sort of crystal control. Hence the reason for crystal oscillators.

(35)

The frequency of older FT-243 crystals can be moved upward by crystal grinding.

I won't be discussing frequency sythesisers and direct digital synthesis (DDS) here.

A practical example of a Crystal Oscillator:-

This is a typical example of the type of crystal oscillators which may be used for say

converters. Some points of interest on crystal oscillators in relation to figure 1.

Figure 1 - schematic of a crystal oscillator

The transistor could be a general purpose type with an Ft of at least 150 Mhz for HF

use. A typical example would be a 2N2222A.

The turns ratio on the tuned circuit depicts an anticipated nominal load of 50 ohms. This

allows theoretical 2K5 ohms on the collector. If it is followed by a buffer amplifier (highly

recommended) I would simply maintain the typical 7:1 turns ratio. I have included a

formula for determining L and C in the tuned circuits of crystal oscillators in case you

have forgotten earlier tutorials. Personally I would make L a reactance of around 250

ohms. In this case I'd make C a smaller trimmer in parallel with a standard fixed value.

RELAY:-

(36)

Relay is a common, simple application of electromagnetism. It uses an electromagnet

made from an iron rod wound with hundreds of fine copper wire. When electricity is

applied to the wire, the rod becomes magnetic. A movable contact arm above the rod is

then pulled toward the rod until it closes a switch contact. When the electricity is

removed, a small spring pulls the contract arm away from the rod until it closes a

second switch contact. By means of relay, a current circuit can be broken or closed in

one circuit as a result of a current in another circuit.

Relays can have several poles and contacts. The types of contacts could be normally

open and normally closed. One closure of the relay can turn on the same normally open

contacts; can turn off the other normally closed contacts.

Relay requires a current through their coils, for which a voltage is applied. This voltage

for a relay can be D.C. low voltages upto 24V or could be 240V a.c.

A relay is an electrical switch that opens and closes under control of another electrical

circuit. In the original form, the switch is operated by an electromagnet to open or close

one or many sets of contacts. It was invented by Joseph Henry in 1835. Because a

relay is able to control an output circuit of higher power than the input circuit, it can be

considered, in a broad sense, to be a form of electrical amplifier.

These contacts can be either Normally Open (NO), Normally Closed (NC), or

change-over contacts.

Normally-open contacts connect the circuit when the relay is activated; the circuit is

disconnected when the relay is inactive. It is also called Form A contact or "make"

(37)

contact. Form A contact is ideal for applications that require to switch a high-current

power source from a remote device.

Normally-closed contacts disconnect the circuit when the relay is activated; the circuit is

connected when the relay is inactive. It is also called Form B contact or "break" contact.

Form B contact is ideal for applications that require the circuit to remain closed until the

relay is activated.

Change-over contacts control two circuits: one normally-open contact and one normally-

closed contact with a common terminal. It is also called Form C contact. Operation:-

When a current flows through the coil, the resulting magnetic field attracts an armature

that is mechanically linked to a moving contact. The movement either makes or breaks

a connection with a fixed contact. When the current to the coil is switched off, the

armature is returned by a force that is half as strong as the magnetic force to its relaxed

position. Usually this is a spring, but gravity is also used commonly in industrial motor

starters. Relays are manufactured to operate quickly. In a low voltage application, this is

to reduce noise. In a high voltage or high current application, this is to reduce arcing.

If the coil is energized with DC, a diode is frequently installed across the coil, to

dissipate the energy from the collapsing magnetic field at deactivation, which would

otherwise generate a spike of voltage and might cause damage to circuit components. If

the coil is designed to be energized with AC, a small copper ring can be crimped to the

end of the solenoid. This "shading ring" creates a small out-of-phase current, which

increases the minimum pull on the armature during the AC cycle. By analogy with the

functions of the original electromagnetic device, a solid-state relay is made with a

thyristor or other solid-state switching device. To achieve electrical isolation, a light-

emitting diode (LED) is used with a photo transistor.

Relays are used:

to control a high-voltage circuit with a low-voltage signal, as in some types of

modems,

to control a high-current circuit with a low-current signal, as in the starter solenoid

of an automobile,

(38)

to detect and isolate faults on transmission and distribution lines by opening and

closing circuit breakers (protection relays),

to isolate the controlling circuit from the controlled circuit when the two are at

different potentials, for example when controlling a mains-powered device from a

low-voltage switch. The latter is often applied to control office lighting as the low

voltage wires are easily installed in partitions, which may be often moved as

needs change. They may also be controlled by room occupancy detectors in an

effort to conserve energy,

to perform logic functions. For example, the Boolean AND function is realized by

connecting NO relay contacts in series, the OR function by connecting NO

contacts in parallel. The change-over or Form C contacts perform the XOR

(exclusive or) function. Similar functions for NAND and NOR are accomplished

using NC contacts. Due to the failure modes of a relay compared with a

semiconductor, they are widely used in safety critical logic, such as the control

panels of radioactive waste handling machinery.

to perform time delay functions. Relays can be modified to delay opening or

delay closing a set of contacts. A very short (a fraction of a second) delay would

use a copper disk between the armature and moving blade assembly. Current

flowing in the disk maintains magnetic field for a short time, lengthening release

time. For a slightly longer (up to a minute) delay, a dashpot is used. A dashpot is

a piston filled with fluid that is allowed to escape slowly. The time period can be

varied by increasing or decreasing the flow rate. For longer time periods, a

mechanical clockwork timer is installed.

(39)

HOW THE RELAY WORK IN THIS PROJECT ?

Relay driver circuit basically provide a on off signal in single pulse. We connect

these pulses to the handsfree of the telephone. When handsfree of the telephone is

activate through the controller then phone is automatic on and last redial number

is dialed. When last number is redialed then after call voice processor is on

automatically and voice signal is transfer to the mobile phone through mike.

to drive a relay we use two transistor circuit. One is NPn and second is PNP

transistor. Output from the controller is connected to the base point of the PNP

transistor through 1 k ohm resistor. Emitter of the PNP transistor is connected to

the positive supply. Collector is connected to the base of the NPN transistor .

(40)

Collector of the NPN transistor is connected to the relay coil. This relay coil press

the handsfree coil and redial the number directl

DIODE:

The simplest semiconductor device is made up of a sandwich of P-type semi conducting

material, with contacts provided to connect the p-and n-type layers to an external circuit.

This is a junction Diode. If the positive terminal of the battery is connected to the p-type

material (cathode) and the negative terminal to the N-type material (Anode), a large

current will flow. This is called forward current or forward biased.

If the connections are reversed, a very little current will flow. This is because under this

condition, the p-type material will accept the electrons from the negative terminal of the

battery and the N-type material will give up its free electrons to the battery, resulting in

the state of electrical equilibrium since the N-type material has no more electrons. Thus

there will be a small current to flow and the diode is called Reverse biased.

Thus the Diode allows direct current to pass only in one direction while blocking it in the

other direction. Power diodes are used in concerting AC into DC. In this, current will flow

freely during the first half cycle (forward biased) and practically not at all during the

other half cycle (reverse biased). This makes the diode an effective rectifier, which

convert ac into pulsating dc. Signal diodes are used in radio circuits for detection. Zener

diodes are used in the circuit to control the voltage.

(41)

(42)

Some common diodes are:-

1. Photo diode.

2. Light Emitting diode.

1. PHOTO DIODE:-

A photo diode is a junction diode made from photo- sensitive semiconductor or

material. In such a diode, there is a provision to allow the light of suitable frequency to

fall on the p-n junction. It is reverse biased, but the voltage applied is less than the

break down voltage. As the intensity of incident light is increased, current goes on

increasing till it becomes maximum. The maximum current is called saturation current

.

2. LIGHT EMITTING DIODE (LED):-

When a junction diode is forward biased, energy is released at the junction diode

is forward biased, energy is released at the junction due to recombination of electrons

and holes. In case of silicon and germanium diodes, the energy released is in infrared

region. In the junction diode made of gallium arsenate or indium phosphide, the energy

(43)

is released in visible region. Such a junction diode is called a light emitting diode or

LED.

*/ This code is written for the purpose of generation of required control signal for

successful operation of programmable number locking system. Comments are given in

front of important function for better understanding of the code. Notation used for

showing comments is according to the assembly language programming. */

'--------------------------------------------------------------

' file: efy20LOC.BAS

' micro conroller based 4 digit code lock

' with timer

'--------------------------------------------------------------

' pass = 1 4 2 8 bin ( 1324) decimal

$crystal = 6000000

$regfile = "89c2051.dat"

Dim I As Byte

Dim K(4) As Byte

Dim Pass(4) As Byte

Dim Key As Byte

Dim Invalid_pass As Bit

Dim Sec_count As Byte

Dim Clock_word As Word

Dim Passtime As Byte

Dim Attempts As Byte

Dim Maxattempts As Byte

(44)

Ready_led Alias P1.0

Relay_out Alias P1.1

For I = 1 To 4

K(i) = 0

Next I

Pass(1) = 1

Pass(2) = 3

Pass(3) = 2

Pass(4) = 4

Sec_count = 0

Passtime = 5

Attempts = 0

Maxattempts = 3

Config Lcd = 16 * 2

Config Lcdpin = Pin , Db4 = P1.4 , Db5 = P1.5 , Db6 = P1.6 , Db7 = P1.7 , E = P1.3 , Rs

= P1.2

'port 1

P1 = 0

P3 = 255

Config Timer0 = Timer , Gate = Internal , Mode = 2

'Timer0 use timer 0

'Gate = Internal no external interrupt

'Mode = 2 8 bit auto reload

(45)

' set t0 internal interrupt 2000 times a sec

On Timer0 Timer_0_overflow_int

Load Timer0 , 250

Priority Set Timer0

Enable Interrupts

Enable Timer0

Begin:

If Attempts >= Maxattempts Then

Locate 0 , 0 : Lcd Maxattempts ; " attempts over"

Locate 2 , 0 : Lcd "try after 10 seconds"

Attempts = 0

Gosub Trylater

End If

Sec_count = 0

For I = 1 To 4

K(i) = 0

Next I

Cls

Cursor On Blink

'clear the LCD display

Lcd "Enter Pass:"

'display this at the top line

Ready_led = 1

(46)

For I = 1 To 4

While 1 = 1

If Sec_count > Passtime Then

Exit For

End If

If P3 <> 255 Then

' some key pressed - check it

If I = 1 Then

' start timer0 on first keystroke

Sec_count = 0

Start Timer0

End If

Key = P3

' wait for key release

While Key = P3

Wend

K(i) = 255 - Key

If K(i) = 1 Then

Goto Lcd_out

End If

If K(i) = 2 Then

Goto Lcd_out

End If

If K(i) = 4 Then

K(i) = 3

Goto Lcd_out

(47)

End If

If K(i) = 8 Then

K(i) = 4

Goto Lcd_out

End If

If K(i) = 16 Then

K(i) = 5

Goto Lcd_out

End If

If K(i) = 32 Then

K(i) = 6

Goto Lcd_out

End If

If K(i) = 128 Then

K(i) = 7

Goto Lcd_out

End If

' invalid key combination

Key(i) = 0

Lcd_out:

Lcd K(i)

Waitms 30

Exit While

End If

Wend

(48)

Next I

Ready_led = 0

Stop Timer0

' check if time over

If Sec_count > Passtime Then

Locate 2 , 0 : Lcd "time over"

Incr Attempts

Gosub Error_flash

Wait 1

Goto Begin

End If

' check valdity

Invalid_pass = 0

For I = 1 To 4

If K(i) <> Pass(i) Then

Invalid_pass = 1

End If

Next I

If Invalid_pass = 1 Then

Goto Invalid

End If

Valid:

(49)

Locate 2 , 0 : Lcd "valid password"

Relay_out = 1

Wait 3

Relay_out = 0

Goto Begin

Invalid:

Locate 2 , 0 : Lcd "invalid"

Gosub Error_flash

Incr Attempts

Wait 1

Goto Begin

Trylater:

' wait for 10 seconds

For I = 1 To 10

Wait 1

Key = P3

Key = 255 - Key

If Key = 3 Then

Exit For

End If

Next I

Wait 2

Return

Error_flash:

(50)

For I = 1 To 10

Ready_led = Ready_led Xor 1

Waitms 100

Next I

Ready_led = 0

Return

' interrupt subroutine -----------------

Timer_0_overflow_int:

' program comes here 2000 times a sec with a 6mhz xtal

Incr Clock_word

If Clock_word > 2000 Then

Clock_word = 0

Incr Sec_count

End If

Return

End

(51)

LPG GAS SENSOR

INTRODUCTION

Hazardous and combustible gases escaping undetected pose great risk of a

disaster .A disaster may cause immense loss of human life and property. Continuous

gas monitoring and alarm system provide the first line of defence.

The electronic gas alarm system employs a unique technology to sense LPG and

NATURAL GAS in its surrounding and is state of the art circuit makes the highly useful

for sensing gas leakage .On sensing gas leakage ,more than the preset level the unique

triggers an inbuilt buzzer ,which keeps giving a sound alarm till gas leakage

continuous .The alarm stops sounding when safety is found .This makes human aware

of the disastrous situation in advance and enables them to act and averts a possible

disaster.

What is LPG?

Liquefied petroleum gas (also called LPG, LP Gas, or auto gas) is a mixture of

hydrocarbon gases used as a fuel in heating appliances and vehicles, and increasingly

(52)

replacing chlorofluorocarbons as an aerosol propellant and a refrigerant to reduce

damage to the ozone layer.

Varieties of LPG bought and sold include mixes that are primarily propane, mixes that

are primarily butane, and the more common, mixes including both propane (60%) and

butane (40%), depending on the season—in winter more propane, in summer more

butane. Propylene and butylenes are usually also present in small concentration. A

powerful odorant, ethanethiol, is added so that leaks can be detected easily. The

international standard is EN 589.

LPG is manufactured during the refining of crude oil, or extracted from oil or gas

streams as they emerge from the ground.

At normal temperatures and pressures, LPG will evaporate. Because of this, LPG is

supplied in pressurised steel bottles. In order to allow for thermal expansion of the

contained liquid, these bottles are not filled completely; typically, they are filled to

between 80% and 85% of their capacity. The ratio between the volumes of the

vaporised gas and the liquefied gas varies depending on composition, pressure and

temperature, but is typically around 250:1. The pressure at which LPG becomes liquid,

called its vapour pressure, likewise varies depending on composition and temperature;

for example, it is approximately 220 kilopascals (2.2 bar) for pure butane at 20 °C (68

°F), and approximately 2.2 megapascals (22 bar) for pure propane at 55 °C (131 °F).

LPG is heavier than air, and thus will flow along floors and tend to settle in low spots,

such as basements. This can cause ignition or suffocation hazards if not dealt with.

Production

LPG is synthesised by refining petroleum or 'wet' natural gas; it was first produced in

1910 by Dr. Walter Snelling, and the first commercial products appeared in 1912. It

currently provides about 3% of the energy consumed.

COMPONENTS USED:-

NAME

(53)

1. Power supply (12-0-12, 11 amp)

2. Resisters

3. Capicators (1000mf, 25v)

4. Diode

5. Gas sensors (MQ-5)

6. Hot wires

7. Buzzer

8. Operational amplifier

9. Transistor

10.IC7812

Working Principle:-

A hot wire sensor consist of two heated elements ,over a compensator , which act as

zero leak reference resistance and the other a catalyst coated active sensor head called

the detector .

In the presence of L.P. gas ,the sensors dements burns a small sample of gas

(ie L.P. gas reacts with the basically coated bead mounted on a hot wire ),decreasing

the resistance of the wire ,to which the sensor is bounded . the change in resistance of

the detector is providing a current in the wire . This change in current is quit high ie,

about 8 to 10 times of the new gas leakage conditions.

This rise in the current is compared and fed to the operational amplifier circuit .This

operational amplifier is operated in the non inverting mode and used as current to

voltage converter .The observation in the current & voltage at various pins of the

operational amplifier are taken with and without gas injected condition. It is observed

that during the gas leakage event the voltage is increased from the value of 0.54 volts to

0.79 volts ,which is sufficient to activate the buzzer & give a warning in case of L.P. gas

leakage , within few seconds .So this circuit is fast in response and & can further be

(54)

i/p +16V

-12vto-16v

1000µF25V

-12to16V

-12V

230V AC

12V

0V

7912

781222

780555

GND 0V

o/p-12vTo pin no. 4Of

Op-amp

Step down transformer

-12

modified by operating a solenoid to cut of the gas supply & for also digital display so the

warning system becomes full proof.

This change in voltage can be further enhanced as per the requirement of the various

circuit activation that is for alarm /digital display or automatic shutting off the lpg supply

to check further leakage.

CIRCUIT DIAGRAM:-

VOLTAGE TO CURRENT CONVERTER

(55)

Current i/pFrom sensor pin no. 4,6

GND

Vooooo

2

3

4-12v

+12v7

o/p voltage

----µA741

1kΩ 10kΩ

Current to Voltage Converter (in inverting mode)

buzzer

µA741

7

3

(56)

To pin no.2of OP-Amp µA741

Vo

5V-10V

+ -

1,3 1,6

5

2

+

-

_

5V±0.1V

L.P.G. SENSOR

Vo Op-Amp 7411,3 4,66

5v-10v

LPG SENSOR

Precautions:-

1. Mount the components at the appropriate places before soldering. Follow the

circuit description and components details, leads identification etc. Do not start

soldering before making it confirm that all the components are mounted at the right

place.

2.Do not use a spread solder on the board, it may cause short circuit.

3.Do not sit under the fan while soldering.

4.Position the board so that gravity tends to keep the solder where you want it.

5.Do not over heat the components at the board. Excess heat may damage the

components or board.

6.The board should not vibrate while soldering otherwise you have a dry or a cold joint.

7.Do not put the kit under or over voltage source. Be sure about the voltage either dc or

ac while operating the gadget.

8.Do spare the bare ends of the components leads otherwise it may short circuit with

the other components. To prevent this use sleeves at the component leads or use

sleeves wire for connections.

(57)

9.Do not use old dark color solder. It may give dry joint. Be sure that all the joints are

clean and well shiny.

FIRE ALARM

CONTENTS:-

1. INTRODUCTION

2. COMPONENTS USED

3. WORKING

4. CIRCUIT DIAGRAM

5. PRECAUTIONS

(58)

INTRODUCTION:-

A Fire Alarm is an active fire protection system that detects fire or the effects of fire,& as

a result provides the indication to person in surrounding.

Now a days the extreem use of electronic appliances may cause of accident like short

circuiting due to which wires or some extra things can catch the fire.

So to over come from this problem Fire Alarm play an vital role in the new generation

safety.This can be use in shops,house etc.

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COMPONENTS USED:-

NAME QUANTITY

1. PCB [CODE 5TP11] 1

2. RESISTANCE

1K 1

47K 2

56K 2

100K PRESET 1

3.CAPACITOR

0.01PF

0.01

1220MFD/16V 1

10MFD/25V 1

4. SEMI CONDUCTOR

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IC 555 1

TRASISTOR 547 1

DR 25 DIODE 1

IC BASE 1

5. BUZZER 1

WORKING OF FIRE ALARM:-

In thus project when the current will be given from 9v supply then it start to flow in the

circuit.

Then the supply goes to the 8pin which is Vcc & also at 4pin which is reset of IC555.

For the protection of IC there is 47k resistance.

Then current goes to the 56k resistance in series there is variable resistance of 100k to

the base

Terminal to transistor it will be connected.LDR which resistance changes as the

temperature changes.

Its property is that as the temperature increases its value decreases when the

temperature of variable

Resistance & LDR match then the current will start to flow through the base of the

transistor.

The emitter terminal is grounded current will flow only through the collector.

There is 56k resistance between terminal 5& 7.

0.1fmd capacitor is used for the controlling of IC. From the 3 terminal of the IC we take

the output.

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There are two capacitor of different value used for the controlling of current so that we

can protect the

Circuit & also buzzer.

IC-555:-

1. GROUND (PIN 1):- This pin is directly connected to ground.

2. Trigger (PIN2):- This pin is the input to the lower comparator, is used to set

The latch,which in turn cause the output to go high.

3. Output(PIN 3):- output high is about 1.7v less tha of Isource upto 200mA while

output low is capable of Isink upto 200mA.n supply.output high is capable

4 .Reset(PIN4):- This is used to reset the latch & return the output to a low state

The reset is an overriding function.when not used connect to v timer is used in

voltage control control mode. When not used connect to ground through a 0..1mfd

capacitor.v++.

5.Control(PIN 5):-Allows access to the 2/3+ voltage divider point when the 555

6. Threshold(PIN6 ):-This is an input to the an upper comparator.

7. DISCHARGE (PIN7):- Tuis is open collector in given figure.

8. V+(PIN8):-This connects to vcc and the ICM7555 cmos version operates 3v-16v

DC while the NE555 version is 3v-16v DC.

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CIRCUIT DIAGRAM:-

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PRECAUTIONS:-

1.Do not implement the Diode(Fire Sensor) which is inside the circuit to with the

PCB.otherwise it may be dangerous to the PCB components.

2.Check the Base , Emitter and Collector of the transistor with the help of multimeter at

the time of built the circuit.

3.keep in mind about the polarity of condenser at pin no. 6 of IC 555 .

4. Take care about the terminal diode menas anode & cathode.

5.Don’t soldering IC directly on the PCB because there is strong possibility to fired the

IC.so always use the base of IC

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During the soldering.

WATER LEVEL INDICATOR WITH ALARM

CONTENTS:-

1. INTRODUCTION

2. COMPONENTS

3. WORKING OF WATER LEVEL INDICATOR

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4. CIRCUIT DIAGRAM

5. PRECAUTIONS

INTRODUCTION:-

This circuit not only indicates the amount of water present in the overhead but also an

alarm when the tank is full.

When the water comes on the top of the tank than automatically alarm will start , buzzer

is there of the audioable sound.

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So that loss of water & also extra consumtion of electricity can be control. This is a

simple but important project in daily life.

Thus water level alarm becomes the basic requirement for every home.

COMPONENTS:-

NAME QUANTITY

1. PCB 1

2.Trasistor BC 148 4

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3.Resistance

10k 1

47k 4

470k 4

4.LED of different colour 4

5.Preset

47k 1

100k 1

6.Capacitor

100mfd 2

0.01mfd 1

7.Speaker 1

WORKING:-

In this circuit there are four different level of water which will be measured, the supply of

9volts

given to the circuit the current will start to flow. Then through the wire A it goes in to

water

Remember one think that wire A must be touch to the bottom of the tank.

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When current goes to the tank there are four wire at different level present, so

when the

Tank start to fill simultaneously a complete circuit will be form through the wire B.

At that time current flow through it & goes to the resistance 47k where it control the

current flow

Otherwise transistor will be fired only for the projection of the transistor we put the 47k

resisitance

There one more resistance of 470k that also do the same work means for the

protection.

The emitter of the transistor is grounded from base current will flow. At the

collector terminal

of the transistor LED is placed so that when current goes to the LED through the

collector

,it start to glow here only 1.5v comes.

Similarly some principle also apply for all other LED’s. in the last when the tank

completely filled

then the current goes at the terminal 4 of the IC-555 it triggered , from the output

terminal of the IC

there is capacitor through which current goes to the speaker & start to blow.

One more think to remember never two different wire should be shorted.

IC-555:-

1.GROUND (PIN 1):- This pin is directly connected to ground.

2.Trigger (PIN2):- This pin is the input to the lower comparator, is used to set

The latch,which in turn cause the output to go high.

3.Output(PIN 3):- output high is about 1.7v less than supply.output high is capable of

Isource upto 200mA while output low is capable of Isink upto 200mA.

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4.Reset(PIN4):- This is used to reset the latch & return the output to a low state. The

reset is an overriding function.when not used connect to v++.

5.Control(PIN 5):-Allows access to the 2/3+ voltage divider point when the 555 timer

is used in voltage control control mode. When not used connect to ground through a

0..1mfd capacitor.

6.Threshold(PIN6 ):-This is an input to the an upper comparator.

7.DISCHARGE (PIN7):- Tuis is open collector in given figure.

8.V+(PIN8):-This connects to vcc and the ICM7555 cmos version operates 3v-16v

DC while the NE555 version is 3v-16v DC.

CIRCUIT DIAGRAM:-

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PRECAUTIONS:-

1. Firstly check all the components that are doing work properly.

2. Carefull about the terminal of IC & transistor .

3. During LED’s fitting Take care during soldering no short circuiting.

4. take care about the terminal & colour also.

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REFERENCES:-

The following books are used for reference in our project:

Op-amps and linear integrated circuits

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By Ramakant A. Gayakward

8051 Microcontroller

By M. A. Mazidi

The following web references have been used for our project:

www.google.co.in

www.electronic-circuits-diagram.com

www.dnatechindia.com

www.hed-software.com

IMAGE GALLERY

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