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a report format for EI PROJECTS ,H.C.S.T MATHURA U.P
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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)
(3)
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
(4)
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:-
(5)
“ 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
(1)
(6)
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
(7)
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.
(8)
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.
(9)
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.
\
(10)
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.
(11)
Fig. : Actual-size, single-side PCB of microcontroller-based code lock
(12)
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.
(13)
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)
(14)
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
(15)
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
(16)
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.
(17)
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
(18)
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
(19)
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
(20)
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
(21)
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.
(22)
(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.
(23)
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
(24)
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.
(25)
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.
(26)
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
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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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