currency counting machine with fake note detection project report
TRANSCRIPT
Currency Counting Machine with Fake Note Detection
1. INTRODUCTION
The currency counting machine or CCM is one of the miracle of the science. The CCM
works on the principle on the breadth of the bundle of currency and there in an roller which
has rods in an continuous pattern and the roller moves these rods with a particular speed.
The speed remains constant as like in the ATM machine counting machine and these
rollers moves on the bundle of the currency and just move out the single currency one by
one at a constant and high speed and there is an transducers which detect that how many
single currency has passed out in front of it.
FIG- 1 500 rupees note with its various real identification mark.
Different range of counting machines like Basic Note counter, Intelligent Counting cum
counterfeit detection machines and Hi Speed Heavy duty cash counting machine are
available to suit different type of customers. Highly dependable and ideal for Banks, Big &
small business houses, Traders, retailers, jewellers and almost all types of business
establishment can use them according to their suitability.
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The machine meant for detection of fake notes as prime function invariably should be
capable of not allowing any fake note to pass as genuine. It is possible only with the
detectors specially developed considering the large number of intricacies concerning to
Indian notes
The kind of machines Indian Banks at cash counters needed are the machine which can
verify not only the images but also can check the chemical and physical properties of
papers, inks, resins and other materials used in production of note. The machine should be
capable of not allowing any fake note to pass as genuine. It is possible only with the
detectors specially developed considering the large number of intricacies concerning to
Indian notes
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2. LITERATURE REVIEW
Currency Counter provides a fast, efficient and accurate way to count stacks of currency.
Some models detect counterfeit bills either magnetically and/or using ultraviolet light.
Ultra Violet Light Detector is used in Currency counters. Currency created by a color
copier or printer produces an image that rests on the surface of paper that can easily be
seen when UV light is placed over it.
FIG- 2 A 500 rupees note under UV rays.
Tiny particles of toner outside the image can also be easily seen with a UV light. Bill
counters and counterfeit detectors have a UV light built into the machine. If a counterfeit
bill is run through the machine, an alarm or light will alert you that the banknote is
counterfeit. Magnetic sensors: Magnetic sensors run over each bill and are designed to
search for certain components of banknotes that cannot be seen by the naked eye.
Machines automatically detect and match the piece against the already-programmed
components of legitimate bills. When a suspicious note is found, the operator is notified
immediately.
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FIG- 3 Noting the discrepancy.
Different range of counting machines like Basic Note counter, Intelligent Counting cum
counterfeit detection machines and Hi Speed Heavy duty cash counting machine
Highly dependable and ideal for Banks, Big & small business houses, Traders, retailers,
jewellers and almost all types of business establishment…
2.1 COUNTERFEITING TECHNIQUES
Counterfeiting, of whatever kind, has been occurring ever since humans grasped the
concept of valuable items, and there has been an ongoing race between certifier (banks, for
example) and counterfeiter ever since.
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First-Line Inspection Methods
Varied-Density Watermarks
Ultraviolet Fluorescence
Intaglio Printing
Microtext
Holograms and Kinegrams (DOVIDs/ISIS)
Second-Line Inspection Methods
Isocheck/Isogram
Fibre-Based Certificates of Authenticity
Colour and Feature Analysis
First-Line Inspection Methods
First-line inspection methods are used on-the-spot by vendors and retailers to determine, at
best guess, the authenticity of currency being exchanged. The disadvantages of these
methods are that they are generally easier to counterfeit than second-line inspection
characteristics, since they’re just as visible to the counterfeiter as to the verifier, and the
methods used to apply them are usually inexpensive. However, the visibility of these
features means that the general population is aware of the security measures and can spot
many fraudulent notes quickly.
Varied-Density Watermarks
By varying the density of the paper a banknote is printed on in a controlled manner, thin
watermarks can be applied. These are visible when a bright light shines onto the rear of
banknote, and the varied paper density causes varying intensities of light to pass through,
causing the watermarked image to appear on the other side of the note.
Ultraviolet Fluorescence
Embedding fluorescent fibers into the paper, or printing ultra-violet ink onto the paper,
creates a form of optical verification easily used at counters, checkouts, etc. By exposing
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the note to ultra-violet light, the ink or fibers fluoresce, revealing a coloured pattern not
visible under natural light.
Intaglio Printing
This gives a more complex and reliable first-line inspection method, since it is the printing
process itself that serves to vouch for the authenticity of the document. The note is
subjected to a high-pressure printing process that strengthens and slightly raises the paper’s
surface structure. Using different alignments of lines printed in this manner, a latent image
can be produced which changes appearance depending on the angle at which the note is
viewed. This method can also be used with optically-variable ink to produce interference
which shows different spectral colours when viewed from different angles.
Micro text
It is very common for banknotes to have incredibly small text printed at much higher
resolutions than most commercial copiers, scanners or printers are capable of. When a
copying or scanning attempt is made, the insufficient resolution causes the text to become
illegibly blurred, announcing the illegitimacy of the note. This method requires specialised
printing equipment but ultimately adds very little cost to the manufacture of the currency.
Holograms and Kin grams (DOVIDs/ISIS)
These techniques are becoming more and more regularly used in modern anti-
counterfeiting measures, once used mostly on credit/debit cards but now increasingly on
new bank notes and cheques. In producing diffractive optically-variable image devices
(DOVIDs), iridescent foils are added to the printed currency usually after printing. Kin
grams and holograms used in DOVIDs are produced by embossing micro profiles with
thermoplastic films.
The hologram itself is applied using the interference of light from different sources in a
specific pattern, and kin grams are produced with achromatic and polarisation effects. The
result is a seemingly 3D full-colour image when illuminated from different angles. ISIS
uses stacked quantities of thin films to create a similar effect, with each layer having
different refractive properties. The refraction of light when viewed is such that a spectral
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pattern has been extracted and a full-colour image is produced which varies under different
viewing angles.
Second-Line Inspection Methods
A second-line inspection method is one that cannot be verified by the naked eye alone, and
requires an extra device to perform a verification function. These are more secure and
harder to counterfeit than visual methods, but the extra security adds extra cost at both the
manufacturing and verification ends.
Isocheck/Isogram
Related to intaglio printing (described above), these methods rely on a specific pattern of
dots and/or lines to cause a moiré pattern when printed or scanned. Hidden watermarks can
also be applied in these patterns such that when a special filter is placed between the
viewer and the note, the hidden verification is revealed and verifies the note as genuine.
Fibre-Based Certificates of Authenticity
Based on the characteristics of fibre-optic light transmission, this method makes use of
unique configurations of fibres embedded in the paper. Using a scanner to illuminate one
end of an embedded fibre, the other corresponding of that fibre will become illuminated.
By using the position of both illuminated ends (the one deliberately illuminated, and the
one illuminated as a result), the certifier has a “fibre signature”.
This string can then be converted into a bit string and combined with any extra data that is
required (e.g. value, serial number, source, etc.). This is in turn combined with a
cryptographic hash of itself and is signed using a private key, with the corresponding
public key made available. The final result of these steps can then be encoded onto the
banknote (this method is suitable for certifying a wide range of other documents too) in the
form of a barcode or verification number of some kind.
Verifying the authenticity merely involves inverting the above process. The control
number is verified using the public key corresponding to the private key initially used. The
hash function is inverted and the original data string extracted. The note is then scanned
using the same fibre illumination method described above, and if the extracted data
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matches the scanning observations, the document is genuine. This technique can add a
large cost to the manufacturing process of banknotes, but is highly secure and very difficult
to illegitimately replicate. It may be excessive for smaller-value currencies, but for large-
value notes, cheques or money orders this method provides a guarantee of the authenticity
of the claim.
Colour and Feature Analysis
Several image-processing software packages now include a secret detection algorithm to
prevent banknotes from being manipulated in their applications. Possibly by searching for
a specific geometric pattern—five 1mm-large circles arranged like a four-pronged star is
the primary candidate, visible in Euro notes, pounds sterling notes and older now-obsolete
European currency—they classify images of banknotes and refuse any further processing.
Touch & Feel Inspection & Visual Inspection
In spite of such high complications involved with the notes whether genuine or fake it has
been largely observed that validity of notes has been checked by the cashiers
simultaneously while manual counting.
However the human aptitudes of visual & touch feel verification with or without handy
tools is having large numbers of natural limitations, not enough to serve the purpose of
detection at cash counters, as there have been many invisible, high end & “difficult to
forge” security features on the valid notes which invariably are supposed to be examined
accurately while verifying validity on the notes seems to have remain unchecked, requiring
highly sophisticated machine to examine the intricacies of security features of the valid
notes.
2.2 ESTIMATED EXPENDITURE
Although estimating the total expenditure for a project of this nature is a mean task in
itself, we try to present the facts in as comprehensive a manner as possible.
Following is a list of the hardware and processes used in the project along with their costs.
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S.No. Name of device Quantity Cost per unit Total cost
1 AT89c51 1 40 40
2 LCD 1 250 250
3 DC Motor 1 400 400
5 Capacitor 6 2 12
6 Resistor 6 1 6
9 12 V Battery 1 800 800
11 Relay 7 35 105
12 ULN2003A 1 15 15
13 7805 1 10 15
14 Switch 2 2 4
Security Features of Indian Banknotes
Watermark
Security Thread
Latent Image
Microlettering
Intaglio
Identification Mark
Fluorescence
Optically Variable Ink
See through Register
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Watermark
The Mahatma Gandhi Series of banknotes contain the Mahatma Gandhi watermark with a
light and shade effect and multi-directional lines in the watermark windowThere is also
the watermark of the price of currency it’s visible in presence of light & glow in uv.
Security Thread
Rs.1000 notes introduced in October 2000 contain a readable, windowed security thread
alternately visible on the obverse with the inscriptions ‘Bharat’ (in Hindi), ‘1000’ and
‘RBI’, but totally embedded on the reverse. The Rs.500 and Rs.100 notes have a security
thread with similar visible features and inscription ‘Bharat’ (in Hindi), and ‘RBI’.
When held against the light, the security thread on Rs.1000, Rs.500 and Rs.100 can be
seen as one continuous line. The Rs.5, Rs.10, Rs.20 and Rs.50 notes contain a readable,
fully embedded windowed security thread with the inscription ‘Bharat’ (in Hindi), and
‘RBI’. The security thread appears to the left of the Mahatma's portrait. Notes issued prior
to the introduction of the Mahatma Gandhi Series have a plain, non-readable fully
embedded security thread.
Latent image
On the obverse side of Rs.1000, Rs.500, Rs.100, Rs.50 and Rs.20 notes, a vertical band on
the right side of the Mahatma Gandhi’s portrait contains a latent image showing the
respective denominational value in numeral. The latent image is visible only when the note
is held horizontally at eye level.
Microlettering
This feature appears between the vertical band and Mahatma Gandhi portrait. It contains
the word ‘RBI’ in Rs.5 and Rs.10. The notes of Rs.20 and above also contain the
denominational value of the notes in microletters. This feature can be seen better under a
magnifying glass
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Intaglio Printing
The portrait of Mahatma Gandhi, the Reserve Bank seal, guarantee and promise clause,
Ashoka Pillar Emblem on the left, RBI, Governor's signature are printed in intaglio i.e. in
raised prints, which can be felt by touch, in Rs.20, Rs.50, Rs.100, Rs.500 and Rs.1000
notes.
Identification Mark
A special feature in intaglio has been introduced on the left of the watermark window on
all notes except Rs.10/- note. This feature is in different shapes for various denominations
(Rs. 20-Vertical Rectangle, Rs.50-Square, Rs.100-Triangle, Rs.500-Circle, Rs.1000-
Diamond) and helps the visually impaired to identify the denomination.
Fluorescence
Number panels of the notes are printed in fluorescent ink. The notes also have optical
fibers. Both can be seen when the notes are exposed to ultra-violet lamp. When there is
fake note it’s letter and mainly the numeric values all are irregular in shape..For a genuine
currency note, the number will be regular and when scrutinized against ultra violet rays,
the letter printed with fluorescent ink shine ,for fake note number will be comparatively
smaller as compared the original one..
Optically Variable Ink
This is a new security feature incorporated in the Rs.1000 and Rs.500 notes with
revised color scheme introduced in November 2000. The numeral 1000 and 500 on the
obverse of Rs.1000 and Rs.500 notes respectively is printed in optically variable ink viz., a
colour-shifting ink. The colour of the numeral 1000/500 appears green when the note is
held flat but would change to blue when the note is held at an angle.
See through Register
The small floral design printed both on the front (hollow) and back (filled up) of the note
in the middle of the vertical band next to the Watermark has an accurate back to back
registration. The design will appear as one floral design when seen against the light.
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2.3 RBI GUIDELINES CONCERNING TO FAKE NOTE
DETECTION
It has necessitated for the Banks to deploy such authenticators which can support Banks to
comply RBI guidelines concerning to fake notes detection. The machine should be 100%
accurate in detection of Fake Notes. No fake note should pass as genuine in all case, have
been the bottom lines for any machine which functions as authenticator unless the note is
of extremely bad quality.
The extremely bad quality of note should be rejected by the authenticators with error codes
“No judgment” since the TRUE validity of such notes due to bad quality can not be judged
except at forensic lab. Such bad quality of notes generally reflects overlapping of features
of genuine & fake note creating, uncertainty of accurate validation even though best
authenticators for not permitting deep scanning of such notes. No sorter or Currency
Verification Systems (CVS) possesses any separate pocket to separate fake notes except
pockets for separating notes of opposite criterion. Sorters just separate the notes which are
not matching with the sorting criterion set in the machine. Fit & unfit, oriented and non
oriented, face up & face down.
There are pockets for collecting opposite criterion notes but no separate pocket have been
there for collection of fake notes; although it has been claimed that sorters are best suited
for fake note detection. It is wrongly presumed that the opposite criterion pocket collect the
fake notes. There is every chance that fake notes matching the various set criterion as may
be set in the sorter will pass under such set criterion for many technical reasons.
The functions of AUTHENTICATION & SORTING are two mutually exclusive functions
carrying wide difference in their respective weight ages and money values involved in the
respective operations. Imperfect quality sorting of notes does not attracts loss of value
while as passing fake notes as genuine attracts direct loss of value and criminal procedures
under I PC and other provisions. Authentication function needs detailed analyses of
chemical & physical properties of Bank Note Paper, varied inks, resins, security threads,
chemical used in the printing process.
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It includes checking of all security features on the face of the notes images, emblems,
portraits, logos, colours, designs, texts, covert and overt features etc Most accurate
authenticity check only is possible if the notes are checked length wise. Authenticators
must have capacity to scan the notes length wise back to back, to match with the large
number of length wise prints, texts, emblems, portraits, horizontal lines; patterns etc for
checking the continuity of such security features while as sorters are checking the notes
width wise loosing the continuity of scanning various lengthwise security features.
Most of the security features in any currency types are designed length wise and hence
without lengthwise scanning of the notes scientifically difficult to obtained 100% accuracy
during the detection of fake notes. Most of the note counting /sorting machines in the
international market have failed to offer 100% authentication accuracy for not having
facility to check notes length wise and scanning the notes width wise, as also have been
dependent on light & image based technology scanning the notes width wise, which have
been scientifically unfeasible. It is scientifically impossible to check highly complicated,
inter related security aspects in the notes with inter related large numbers of permutations
and combinations of each and every elements that constitutes a Genuine notes at the high
speeds of sorters which sorts the notes with Image & light sensor based technology.
Speed kills the authentication accuracy by note getting scientific time to pip into the
minute differences between genuine and fabricated security features. At the most can
detect very poorly fabricated notes but not skilfully fabricated fake notes being pumped in
our country by other state supports that have been having total infrastructures and notes
printing technology Authentication can only be carried out with high end light cum Image
cum digital technology. The fastest fake note detector that is available in the international
market takes minimum 3 seconds for thorough checking of notes. Such machines mostly
have facility for single note manual feedings.
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3. MATERIALS AND METHODOLOGY
3.1 METHODOLOGY
The whole system is controlled by the microcontroller (AT89c51). The currency counting
machine or CCM .The CCM works on the principle on the breadth of the bundle of
currency and there in an roller which has rods in an continuous pattern and the roller
moves these rods with a particular speed
and these rollers moves on the bundle of the currency and just move out the single
currency one by one at a constant and high speed and there is an transducers which detect
that how many single currency has passed out in front of it.
FIG- 4- Complete circuit diagram.
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3.2 COMPONENTS/PARTS USED:
AT89C51
LCD
DC motors (3)
Drill Motor
Relays
Transformer
Diodes
Resistors
Capacitors
A brief description of these components follows.
AT89C51 microcontroller
The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4
Kbytes of Flash Programmable and Erasable Read Only Memory (PEROM). The
device is manufactured using Atmel’s high density non-volatile memory technology
and is compatible with the industry standard MCS-51Ô instruction set and pin out.
The on-chip Flash allows the program memory to be reprogrammed in-system or by
a conventional non-volatile memory programmer. By combining a versatile 8-bit CPU
with Flash on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer
which provides a highly flexible and cost effective solution to many embedded control
applications.
The Intel MCS-51 (commonly referred to as 8051) is a Harvard architecture, single chip
microcontroller (µC) series which was developed by Intel in 1980 for use in embedded
systems. Intel's original versions were popular in the 1980s and early 1990s. While Intel no
longer manufactures the MCS-51, binary compatible derivatives remain popular today. In
addition to these physical devices, several companies also offer MCS-51 derivatives as IP
cores for use in FPGAs or ASICs designs.
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Intel's original MCS-51 family was developed using NMOS technology, but later versions,
identified by a letter C in their name (e.g., 80C51) used CMOS technology and consumed
less power than their NMOS predecessors. This made them more suitable for battery-
powered devices.
FIG- 5 AT89C51 microcontroller.
AT89C51
Important features and applications of 8051 micro architecture.
The 8051 architecture provides many functions (CPU, RAM, ROM, I/O, interrupt logic,
timer, etc.) in a single package
8-bit ALU, Accumulator and 8-bit Registers; hence it is an 8-bit microcontroller
8-bit data bus – It can access 8 bits of data in one operation
16-bit address bus – It can access 216 memory locations – 64 KB (65536 locations) each
of RAM and ROM
On-chip RAM – 128 bytes (data memory)
On-chip ROM – 4 kByte (program memory)
Four byte bi-directional input/output port
UART (serial port)
Two 16-bit Counter/timers
Two-level interrupt priority
Power saving mode (on some derivatives)
One particularly useful feature of the 8051 core was the inclusion of a boolean processing
engine which allows bit-level boolean logic operations to be carried out directly and
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efficiently on select internal registers and select RAM locations. This advantageous feature
helped cement the 8051's popularity in industrial control applications because it reduced
code size by as much as 30%. Another valued feature is the including of four bank
selectable working register sets which greatly reduce the amount of time required to
complete an interrupt service routine.
With a single instruction the 8051 can switch register banks as opposed to the time
consuming task of transferring the critical registers to the stack or designated RAM
locations. These registers also allowed the 8051 to quickly perform a context switch which
is essential for time sensitive real-time applications.The MCS-51 UARTs make it simple to
use the chip as a serial communications interface. External pins can be configured to
connect to internal shift registers in a variety of ways, and the internal timers can also be
used, allowing serial communications in a number of modes, both synchronous and
asynchronous. Some modes allow communications with no external components.
A mode compatible with an RS-485 multi-point communications environment is
achievable, but the 8051's real strength is fitting in with existing ad-hoc protocols (e.g.,
when controlling serial-controlled devices).Once a UART, and a timer if necessary, have
been configured, the programmer needs only to write a simple interrupt routine to refill the
send shift register whenever the last bit is shifted out by the UART and/or empty the full
receive shift register (copy the data somewhere else). The main program then performs
serial reads and writes simply by reading and writing 8-bit data to stacks.
MCS-51 based microcontrollers typically include one or two UARTs, two or three timers,
128 or 256 bytes of internal data RAM (16 bytes of which are bit-addressable), up to 128
bytes of I/O, 512 bytes to 64 kB of internal program memory, and sometimes a quantity of
extended data RAM (ERAM) located in the external data space. The original 8051 core ran
at 12 clock cycles per machine cycle, with most instructions executing in one or two
machine cycles. With a 12 MHz clock frequency, the 8051 could thus execute 1 million
one-cycle instructions per second or 500,000 two-cycle instructions per second.
Enhanced 8051 cores are now commonly used which run at six, four, two, or even one
clock per machine cycle, and have clock frequencies of up to 100 MHz, and are thus
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capable of an even greater number of instructions per second. All SILabs, some Dallas and
a few Atmel devices have single cycle cores.Features of the modern 8051 include built-in
reset timers with brown-out detection, on-chip oscillators, self-programmable Flash ROM
program memory, built-in external RAM, extra internal program storage, bootloader code
in ROM, EEPROM non-volatile data storage, I²C, SPI, and USB host interfaces, CAN or
LIN bus, PWM generators, analog comparators, A/D and D/A converters, RTCs, extra
counters and timers, in-circuit debugging facilities, more interrupt sources, and extra
power saving modes.In many engineering schools the 8051 microcontroller is used in
introductory microcontroller courses.
Memory architecture
The MCS-51 has four distinct types of memory – internal RAM, special function registers,
program memory, and external data memory. Internal RAM (IRAM) is located from
address 0 to address 0xFF. IRAM from 0x00 to 0x7F can be accessed directly, and the
bytes from 0x20 to 0x2F are also bit-addressable. IRAM from 0x80 to 0xFF must be
accessed indirectly, using the @R0 or @R1 syntax, with the address to access loaded in R0
or R1.
Special function registers (SFR) are located from address 0x80 to 0xFF, and are accessed
directly using the same instructions as for the lower half of IRAM. Some of the SFR's are
also bit-addressable. Program memory (PMEM, though less common in usage than IRAM
and XRAM) is located starting at address 0. It may be on- or off-chip, depending on the
particular model of chip being used. Program memory is read-only, though some variants
of the 8051 use on-chip flash memory and provide a method of re-programming the
memory in-system or in-application. Aside from storing code, program memory can also
store tables of constants that can be accessed by MOVC A, @DPTR, using the 16-bit
special function register DPTR.
External data memory (XRAM) also starts at address 0. It can also be on- or off-chip; what
makes it "external" is that it must be accessed using the MOVX (Move external)
instruction. Many variants of the 8051 include the standard 256 bytes of IRAM plus a few
KB of XRAM on the chip. If more XRAM is required by an application, the internal
XRAM can be disabled, and all MOVX instructions will fetch from the external bus.
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FIG- 6 INTEL 8051 block diagram.
Relay
A relay is an electrically operated switch. Many relays use an electromagnet to operate a
switching mechanism mechanically, but other operating principles are also used. Relays
are used where it is necessary to control a circuit by a low-power signal (with complete
electrical isolation between control and controlled circuits), or where several circuits must
be controlled by one signal. The first relays were used in long distance telegraph circuits,
repeating the signal coming in from one circuit and re-transmitting it to another. Relays
were used extensively in telephone exchanges and early computers to perform logical
operations.
A type of relay that can handle the high power required to directly control an electric
motor or other loads is called a contactor. Solid-state relays control power circuits with no
moving parts, instead using a semiconductor device to perform switching. Relays with
calibrated operating characteristics and sometimes multiple operating coils are used to
protect electrical circuits from overload or faults; in modern electric power systems these
functions are performed by digital instruments still called "protective relays".
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
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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.
Basic design and operation
Small "cradle" relay often used in electronics. The "cradle" term refers to the shape of the
relay's armature. A simple electromagnetic relay consists of a coil of wire wrapped around
a soft iron core, an iron yoke which provides a low reluctance path for magnetic flux, a
movable iron armature, and one or more sets of contacts (there are two in the relay
pictured). The armature is hinged to the yoke and mechanically linked to one or more sets
of moving contacts. It is held in place by a spring so that when the relay is de-energized
there is an air gap in the magnetic circuit. In this condition, one of the two sets of contacts
in the relay pictured is closed, and the other set is open. Other relays may have more or
fewer sets of contacts depending on their function. The relay in the picture also has a wire
connecting the armature to the yoke. This ensures continuity of the circuit between the
moving contacts on the armature, and the circuit track on the printed circuit board (PCB)
via the yoke, which is soldered to the PCB.
When an electric current is passed through the coil it generates a magnetic field that
activates the armature, and the consequent movement of the movable contact(s) either
makes or breaks (depending upon construction) a connection with a fixed contact. If the set
of contacts was closed when the relay was de-energized, then the movement opens the
contacts and breaks the connection, and vice versa if the contacts were open. When the
current to the coil is switched off, the armature is returned by a force, approximately half
as strong as the magnetic force, to its relaxed position. Usually this force is provided by a
spring, but gravity is also used commonly in industrial motor starters. Most relays are
manufactured to operate quickly. In a low-voltage application this reduces noise; in a high
voltage or current application it reduces arcing.
When the coil is energized with direct current, a diode is often placed across the coil to
dissipate the energy from the collapsing magnetic field at deactivation, which would
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otherwise generate a voltage spike dangerous to semiconductor circuit components. Some
automotive relays include a diode inside the relay case.
Alternatively, a contact protection network consisting of a capacitor and resistor in series
(snubber circuit) may absorb the surge. If the coil is designed to be energized with
alternating current (AC), a small copper "shading ring" can be crimped to the end of the
solenoid, creating a small out-of-phase current which increases the minimum pull on the
armature during the AC cycle.[1]A solid-state relay uses a thyristor or other solid-state
switching device, activated by the control signal, to switch the controlled load, instead of a
solenoid. An optocoupler (a light-emitting diode (LED) coupled with a photo transistor)
can be used to isolate control and controlled circuits.
FIG- 7 Relay switch
Relay switch
Crystal Oscillators
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of
a vibrating crystal of piezoelectric material to create an electrical signal with a very precise
frequency. This frequency is commonly used to keep track of time (as in quartz
wristwatches), to provide a stable clock signal for digital integrated circuits, and to
stabilize frequencies for radio transmitters and receivers. The most common type of
piezoelectric resonator used is the quartz crystal, so oscillator circuits designed around
them became known as "crystal oscillators."
Quartz crystals are manufactured for frequencies from a few tens of kilohertz to tens of
megahertz. More than two billion (2×109) crystals are manufactured annually. Most are
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used for consumer devices such as wristwatches, clocks, radios, computers, and cell
phones. Quartz crystals are also found inside test and measurement equipment, such as
counters, signal generators, and oscilloscopes.
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.
Operation
A crystal is a solid in which the constituent atoms, molecules, or ions are packed in a
regularly ordered, repeating pattern extending in all three spatial dimensions.
Almost any object made of an elastic material could be used like a crystal, with appropriate
transducers, since all objects have natural resonant frequencies of vibration. For example,
steel is very elastic and has a high speed of sound. It was often used in mechanical filters
before quartz. The resonant frequency depends on size, shape, elasticity, and the speed of
sound in the material. High-frequency crystals are typically cut in the shape of a simple,
rectangular plate. Low-frequency crystals, such as those used in digital watches, are
typically cut in the shape of a tuning fork.
For applications not needing very precise timing, a low-cost ceramic resonator is often
used in place of a quartz crystal.When a crystal of quartz is properly cut and mounted, it
can be made to distort in an electric field by applying a voltage to an electrode near or on
the crystal. This property is known as piezoelectricity. When the field is removed, the
quartz will generate an electric field as it returns to its previous shape, and this can
generate a voltage. The result is that a quartz crystal behaves like a circuit composed of an
inductor, capacitor and resistor, with a precise resonant frequency.
Quartz has the further advantage that its elastic constants and its size change in such a way
that the frequency dependence on temperature can be very low. The specific characteristics
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will depend on the mode of vibration and the angle at which the quartz is cut (relative to its
crystallographic axes). Therefore, the resonant frequency of the plate, which depends on its
size, will not change much, either.
This means that a quartz clock, filter or oscillator will remain accurate. For critical
applications the quartz oscillator is mounted in a temperature-controlled container, called a
crystal oven, and can also be mounted on shock absorbers to prevent perturbation by
external mechanical vibrations.
Crystal structures and materials
The most common material for oscillator crystals is quartz. At the beginning of the
technology, natural quartz crystals were used; now synthetic crystalline quartz grown by
hydrothermal synthesis is predominant due to higher purity, lower cost, and more
convenient handling. One of the few remaining uses of natural crystals is for pressure
transducers in deep wells. During World War II and for some time afterwards, natural
quartz was considered a strategic material by the USA. Large crystals were imported from
Brazil. Raw "lascas", the source material quartz for hydrothermal synthesis, are imported
to USA or mined locally by Coleman Quartz. The average value of as-grown synthetic
quartz in 1994 was USD60/kg.
Two types of quartz crystals exist: left-handed and right-handed, differing in the optical
rotation but identical in other physical properties. Both left and right-handed crystals can
be used for oscillators, if the cut angle is correct. In manufacture, right-handed quartz is
generally used. The SiO4 tetrahedrons form parallel helixes; the direction of twist of the
helix determines the left- or right-hand orientation. The helixes are aligned along the z-axis
and merged together, sharing atoms. The mass of the helixes forms a mesh of small and
large channels parallel to the z-axis; the large ones are large enough to allow some
mobility of smaller ions and molecules through the crystal.
Quartz exists in several phases. At 573 °C at 1 atmosphere (and at higher temperatures and
higher pressures) the α-quartz undergoes quartz inversion, transforms reversibly to β-
quartz. The reverse process however is not entirely homogeneous and crystal twinning
occurs. Care has to be taken during manufacture and processing to avoid the phase
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transformation. Other phases, e.g. the higher-temperature phases tridymite and cristobalite,
are not significant for oscillators. All quartz oscillator crystals are the α-quartz type.
Infrared spectrophotometry is used as one of the methods for measuring the quality of the
grown crystals. The wavenumbers 3585, 3500 and 3410 cm−1 are commonly used. The
measured value is based on the absorption bands of the OH radical and the infrared Q
value is calculated. The electronic grade crystals, grade C, have Q of 1.8 million or above;
the premium grade B crystals have Q of 2.2 million, and special premium grade A crystals
have Q of 3.0 million. The Q value is calculated only for the z region; crystals containing
other regions can be adversely affected. Another quality indicator is the etch channel
density; when the crystal is etched, tubular channels are created along linear defects. For
processing involving etching, e.g. the wristwatch tuning fork crystals, low etch channel
density is desirable. The etch channel density for swept quartz is about 10–100 and
significantly more for unswept quartz. Presence of etch channels and etch pits degrades the
resonator's Q and introduces nonlinearities. Quartz crystals can be grown for specific
purposes.
Crystals for AT-cut are the most common in mass production of oscillator materials; the
shape and dimensions are optimized for high yield of the required wafers. High-purity
quartz crystals are grown with especially low content of aluminium, alkali metal and other
impurities and minimal defects; the low amount of alkali metals provides increased
resistance to ionizing radiation. Crystals for wrist watches, for cutting the tuning fork
32768 Hz crystals, are grown with very low etch channel density. Crystals for SAW
devices are grown as flat; with large X-size seed with low etch channel density.
Special high-Q crystals, for use in highly stable oscillators, are grown at constant slow
speed and have constant low infrared absorption along the entire Z axis. Crystals can be
grown as Y-bar, with a seed crystal in bar shape and elongated along the Y axis, or as Z-
plate, grown from a plate seed with Y-axis direction length and X-axis width. The region
around the seed crystal contains a large number of crystal defects and should not be used
for the wafers.Crystals grow anisotropically; the growth along the Z axis is up to 3 times
faster than along the X axis. The growth direction and rate also influences the rate of
uptake of impurities. Y-bar crystals, or Z-plate crystals with long Y axis, have four growth
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regions usually called +X, -X, Z, and S. The distribution of impurities during growth is
uneven; different growth areas contain different level of contaminants. The z regions are
the purest, the small occasionally present s regions are less pure, the +x region is yet less
pure, and the -x region has the highest level of impurities.
The impurities have negative impact on radiation hardness, susceptibility to twinning,
filter loss, and long and short term stability of the crystals. Different-cut seeds in different
orientations may provide other kinds of growth regions. The growth speed of the -x
direction is slowest due to the effect of adsorption of water molecules on the crystal
surface; aluminium impurities suppress growth in two other directions. The content of
aluminium is lowest in z region, higher in +x, yet higher in -x, and highest in s; the size of
s regions also grows with increased amount of aluminium present.
The content of hydrogen is lowest in z region, higher in +x region, yet higher in s region,
and highest in -x. Aluminium inclusions transform to colour centres with a gamma ray
irradiation, causing darkening of the crystal proportional to the dose and level of
impurities; presence of regions with different darkness reveals the different growth
regions. The dominant type of defect of concern in quartz crystals is the substitution of
Al(III) for Si(IV) atom in the crystal lattice. The aluminium ion has an associated
interstitial charge compensator present nearby, which can be a H+ ion (attached to the
nearby oxygen and forming a hydroxyl group, called Al-OH defect), Li+ ion, Na+ ion, K+
ion (less common), or an electron hole trapped in a nearby oxygen atom orbital. The
composition of the growth solution, whether it is based on lithium or sodium alkali
compounds, determines the charge compensating ions for the aluminium defects. The ion
impurities are of concern as they are not firmly bound and can migrate through the crystal,
altering the local lattice elasticity and the resonant frequency of the crystal. Other common
impurities of concern are e.g. iron(III) (interstitial), fluorine, boron(III), phosphorus(V)
(substitution), titanium(IV) (substitution, universally present in magmatic quartz, less
common in hydrothermal quartz), and germanium(IV) (substitution).
Sodium and iron ions can cause inclusions of aconite and elemeusite crystals. Inclusions of
water may be present in fast-grown crystals; interstitial water molecules are abundant near
the crystal seed. Another defect of importance is the hydrogen containing growth defect,
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when instead of a Si-O-Si structure a pair of Si-OH HO-Si groups is formed; essentially a
hydrolyzed bond. Fast-grown crystals contain more hydrogen defects than slow-grown
ones. These growth defects source as supply of hydrogen ions for radiation-induced
processes and forming Al-OH defects. Germanium impurities tend to trap electrons created
during irradiation; the alkali metal cations then migrate towards the negatively charged
center and form a stabilizing complex. Matrix defects can be also present; oxygen
vacancies, silicon vacancies (usually compensated by 4 hydrogens or 3 hydrogens and a
hole), peroxy groups, etc. Some of the defects produce localized levels in the forbidden
band, serving as charge traps; Al(III) and B(III) typically serve as hole traps while electron
vacancies, titanium, germanium, and phosphorus atoms serve as electron traps. The
trapped charge carriers can be released by heating; their recombination is the cause of
thermoluminescence.
The mobility of interstitial ions depends strongly on temperature. Hydrogen ions are
mobile down to 10 K, but alkali metal ions become mobile only at temperatures around
and above 200 K. The hydroxyl defects can be measured by near-infrared spectroscopy.
The trapped holes can be measured by electron spin resonance. The Al-Na+ defects show
as an acoustic loss peak due to their stress-induced motion; the Al-Li+ defects do not form
a potential well so are not detectable this way. Some of the radiation induced defects
during their thermal annealing produce thermo luminescence; defects related to aluminium,
titanium, and germanium can be distinguished.
Swept crystals are crystals that have undergone a solid-state electro diffusion purification
process. Sweeping involves heating the crystal above 500 °C in a hydrogen-free
atmosphere, and the voltage gradient of at least 1 kilovolt/cm, for several (usually over 12)
hours. The migration of impurities and the gradual replacement of alkali metal ions with
hydrogen (when swept in air) or electron holes (when swept in vacuum) causes a weak
electric current through the crystal; decay of this current to a constant value signals end of
the process. The crystal is then left to cool, while the electric field is maintained. The
impurities are concentrated at the cathode region of the crystal, which is cut off afterwards
and discarded. Swept crystals have increased resistance to radiation, as the dose effects are
dependent on the level of alkali metal impurities; they are suitable for use in devices
exposed to ionizing radiation, e.g. for nuclear and space technology. Sweeping under
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vacuum at higher temperatures and higher field strengths yields yet more radiation-hard
crystals. The level and character of impurities can be measured by infrared spectroscopy.
Quartz can be swept in both α and β phase; sweeping in β phase is faster, but the phase
transition may induce twinning. Twinning can be mitigated by subjecting the crystal to
compression stress in the X direction, or an AC or DC electric field along the X axis while
the crystal cools through the phase transformation temperature region.
Sweeping can be also used to introduce one kind of an impurity into the crystal. Lithium,
sodium, and hydrogen swept crystals are used for e.g. studying quartz behavior.Very small
crystals for high fundamental mode frequencies can be manufactured by photolithography.
Crystals can be adjusted to exact frequency by laser trimming. A technique used in the
world of amateur radio for slight decrease of the crystal frequency may be achieved by
exposing crystals with silver electrodes to vapours of iodine, which causes a slight mass
increase on the surface by forming a thin layer of silver iodide; such crystals however had
problematic long-term stability. Another method commonly used is electrochemical
increase or decrease of silver electrode thickness by submerging resonator in lapis solved
in water, citric acid in water, or water with salt, and using resonator as one electrode, and
small silver electrode as another.
By choosing direction of current, one can either increase or decrease mass of electrodes.
Details were published in "Radio" magazine (3/1978) by UB5LEV.Raising frequency by
scratching off parts of the electrodes is advised against, as this may damage the crystal and
lower its Q factor. Capacitor trimmers can be also used for frequency adjustment of the
oscillator circuit.
Some other piezoelectric materials than quartz can be employed; e.g. single crystals of
lithium tantalite, lithium niobate, lithium borate, berlinite, gallium arsenide, lithium
tetraborate, aluminium phosphate, bismuth germanium oxide, polycrystalline zirconium
titanate ceramics, high-alumina ceramics, silicon-zinc oxide composite, or dipotassium
tartrate; some materials may be more suitable for specific applications. An oscillator
crystal can be also manufactured by depositing the resonator material on the silicon chip
surface. Crystals of gallium phosphate, langasite, langanite and langanate are about 10
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times more pullable than the corresponding quartz crystals, and are used in some VCXO
oscillators.
Resistors
Resistors (R), are the most commonly used of all electronic components, to the point
where they are almost taken for granted. There are many different resistor types available
with their principal job being to "resist" the flow of current through an electrical circuit, or
to act as voltage droppers or voltage dividers. They are "Passive Devices", that is they
contain no source of power or amplification but only attenuate or reduce the voltage signal
passing through them. When used in DC circuits the voltage drop produced is measured
across their terminals as the circuit current flows through them while in AC circuits the
voltage and current are both in-phase producing 0o phase shift.
Resistors produce a voltage drop across themselves when an electrical current flows
through them because they obey Ohm's Law, and different values of resistance produces
different values of current or voltage. This can be very useful in Electronic circuits by
controlling or reducing either the current flow or voltage produced across them. There are
many different Resistor Types and they are produced in a variety of forms because their
particular characteristics and accuracy suit certain areas of application, such as High
Stability, High Voltage, High Current etc., or are used as general purpose resistors where
their characteristics are less of a problem. Some of the common characteristics associated
with the humble resistor are; Temperature Coefficient, Voltage Coefficient, Noise,
Frequency Response, Power as well as Temperature Rating, Physical Size and Reliability.
In all Electrical and Electronic circuit diagrams and schematics, the most commonly used
resistor symbol is that of a "zigzag" type line with the value of its resistance given in
Ohms, Ω.
Capacitor
Just like the Resistor, the Capacitor or sometimes referred to as a Condenser is a passive
device, and one which stores energy in the form of an electrostatic field which produces a
potential (Static Voltage) across its plates. In its basic form a capacitor consists of two
parallel conductive plates that are not connected but are electrically separated either by air
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or by an insulating material called the Dielectric. When a voltage is applied to these plates,
a current flows charging up the plates with electrons giving one plate a positive charge and
the other plate an equal and opposite negative charge. This flow of electrons to the plates is
known as the Charging Current and continues to flow until the voltage across the plates
(and hence the capacitor) is equal to the applied voltage Vc. At this point the capacitor is
said to be fully charged and this is illustrated below.
Capacitor Construction
FIG- 8 :Capacitor construction
The parallel plate capacitor is the simplest form of capacitor and its capacitance value is
fixed by the equal area of the plates and the distance or separation between them. Altering
any two of these values alters the the value of its capacitance and this forms the basis of
operation of the variable capacitors. Also, because capacitors store the energy of the
electrons in the form of an electrical charge on the plates the larger the plates and/or
smaller their separation the greater will be the charge that the capacitor holds for any given
voltage across its plates.
Liquid Crystal Display
A liquid crystal display (LCD) is a flat panel display, electronic visual display, or video
display that uses the light modulating properties of liquid crystals (LCs). LCs do not emit
light directly.
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FIG- 9 A general purpose alphanumeric LCD, with two lines of 16 characters.
LCDs are used in a wide range of applications, including computer monitors, television,
instrument panels, aircraft cockpit displays, signage, etc. They are common in consumer
devices such as video players, gaming devices, clocks, watches, calculators, and
telephones. LCDs have replaced cathode ray tube (CRT) displays in most applications.
They are available in a wider range of screen sizes than CRT and plasma displays, and
since they do not use phosphors, they cannot suffer image burn-in. LCDs are, however,
susceptible to image persistence.
LCDs are more energy efficient and offer safer disposal than CRTs. Its low electrical
power consumption enables it to be used in battery-powered electronic equipment. It is an
electronically modulated optical device made up of any number of segments filled with
liquid crystals and arrayed in front of a light source (backlight) or reflector to produce
images in color or monochrome. The most flexible ones use an array of small pixels. The
earliest discovery leading to the development of LCD technology, the discovery of liquid
crystals, dates from 1888. By 2008, worldwide sales of televisions with LCD screens had
surpassed the sale of CRT units.
Overview
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Each pixel of an LCD typically consists of a layer of molecules aligned between two
transparent electrodes, and two polarizing filters, the axes of transmission of which are (in
most of the cases) perpendicular to each other. With no actual liquid crystal between the
polarizing filters, light passing through the first filter would be blocked by the second
(crossed) polarizer.
The surface of the electrodes that are in contact with the liquid crystal material are treated
so as to align the liquid crystal molecules in a particular direction. This treatment typically
consists of a thin polymer layer that is unidirectionally rubbed using, for example, a cloth.
The direction of the liquid crystal alignment is then defined by the direction of rubbing.
Electrodes are made of the transparent conductor Indium Tin Oxide (ITO). The Liquid
Crystal Display is intrinsically a “passive” device, it is a simple light valve. The managing
and control of the data to be displayed is performed by one or more circuits commonly
denoted as LCD drivers.
Before applying an electric field, the orientation of the liquid crystal molecules is
determined by the alignment at the surfaces of electrodes. In a twisted nematic device (still
the most common liquid crystal device), the surface alignment directions at the two
electrodes are perpendicular to each other, and so the molecules arrange themselves in a
helical structure, or twist. This induces the rotation of the polarization of the incident light,
and the device appears grey. If the applied voltage is large enough, the liquid crystal
molecules in the center of the layer are almost completely untwisted and the polarization of
the incident light is not rotated as it passes through the liquid crystal layer. This light will
then be mainly polarized perpendicular to the second filter, and thus be blocked and the
pixel will appear black. By controlling the voltage applied across the liquid crystal layer in
each pixel, light can be allowed to pass through in varying amounts thus constituting
different levels of gray.
The optical effect of a twisted nematic device in the voltage-on state is far less dependent
on variations in the device thickness than that in the voltage-off state. Because of this,
these devices are usually operated between crossed polarizers such that they appear bright
with no voltage (the eye is much more sensitive to variations in the dark state than the
bright state). These devices can also be operated between parallel polarizers, in which case
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the bright and dark states are reversed. The voltage-off dark state in this configuration
appears blotchy, however, because of small variations of thickness across the device.
Both the liquid crystal material and the alignment layer material contain ionic compounds.
If an electric field of one particular polarity is applied for a long period of time, this ionic
material is attracted to the surfaces and degrades the device performance. This is avoided
either by applying an alternating current or by reversing the polarity of the electric field as
the device is addressed (the response of the liquid crystal layer is identical, regardless of
the polarity of the applied field).
Displays for a small number of individual digits and/or fixed symbols (as in digital
watches, pocket calculators etc.) can be implemented with independent electrodes for each
segment. In contrast full alphanumeric and/or variable graphics displays are usually
implemented with pixels arranged as a matrix consisting of electrically connected rows on
one side of the LC layer and columns on the other side, which makes it possible to address
each pixel at the intersections. The general method of matrix addressing consists of
sequentially addressing one side of the matrix, for example by selecting the rows one-by-
one and applying the picture information on the other side at the columns row-by-row. For
details on the various matrix addressing schemes see Passive-matrix and active-matrix
addressed LCDs.
Voltage Regulator
The 78xx (sometimes LM78xx) is a family of self-contained fixed linear voltage regulator
integrated circuits. The 78xx family is commonly used in electronic circuits requiring a
regulated power supply due to their ease-of-use and low cost. For ICs within the family,
the xx is replaced with two digits, indicating the output voltage (for example, the 7805 has
a 5 volt output, while the 7812 produces 12 volts). The 78xx line are positive voltage
regulators: they produce a voltage that is positive relative to a common ground. There is a
related line of 79xx devices which are complementary negative voltage regulators. 78xx
and 79xx ICs can be used in combination to provide positive and negative supply voltages
in the same circuit.
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FIG-10 Voltage regulator – LM 78xx
78xx ICs have three terminals and are commonly found in the TO220 form factor,
although smaller surface-mount and larger TO3 packages are available. These devices
support an input voltage anywhere from a couple of volts over the intended output voltage,
up to a maximum of 35 or 40 volts, and typically provide 1 or 1.5 amperes of current
(though smaller or larger packages may have a lower or higher current rating).
Advantages
78xx series ICs do not require additional components to provide a constant, regulated
source of power, making them easy to use, as well as economical and efficient uses of
space. Other voltage regulators may require additional components to set the output
voltage level, or to assist in the regulation process. Some other designs (such as a
switched-mode power supply) may need substantial engineering expertise to implement.
78xx series ICs have built-in protection against a circuit drawing too much power. They
have protection against overheating and short-circuits, making them quite robust in most
applications. In some cases, the current-limiting features of the 78xx devices can provide
protection not only for the 78xx itself, but also for other parts of the circuit.78xx ICs are
easy to use and handle but these cannot give a altering voltage required so Lm317 series of
ICs are available to obtain a voltage output from 1.25 volts to 37 volts.
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Disadvantages
The input voltage must always be higher than the output voltage by some minimum
amount (typically 2 volts). This can make these devices unsuitable for powering some
devices from certain types of power sources (for example, powering a circuit that requires
5 volts using 6-volt batteries will not work using a 7805).
As they are based on a linear regulator design, the input current required is always the
same as the output current. As the input voltage must always be higher than the output
voltage, this means that the total power (voltage multiplied by current) going into the 78xx
will be more than the output power provided. The extra input power is dissipated as heat.
This means both that for some applications an adequate heatsink must be provided, and
also that a (often substantial) portion of the input power is wasted during the process,
rendering them less efficient than some other types of power supplies.
When the input voltage is significantly higher than the regulated output voltage (for
example, powering a 7805 using a 24 volt power source), this inefficiency can be a
significant issue.Even in larger packages, 78xx integrated circuits cannot supply as much
power as many designs which use discrete components, and are generally inappropriate for
applications requiring more than a few amperes of current.
Transformer
A transformer is a device that transfers electrical energy from one circuit to another
through inductively coupled conductors—the transformer's coils. A varying current in the
first or primary winding creates a varying magnetic flux in the transformer's core and thus
a varying magnetic field through the secondary winding. This varying magnetic field
induces a varying electromotive force (EMF), or "voltage", in the secondary winding. This
effect is called inductive coupling.
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FIG- 11. Transformer windings
If a load is connected to the secondary, current will flow in the secondary winding, and
electrical energy will be transferred from the primary circuit through the transformer to the
load. In an ideal transformer, the induced voltage in the secondary winding (Vs) is in
proportion to the primary voltage (Vp) and is given by the ratio of the number of turns in
the secondary (Ns) to the number of turns in the primary (Np) as follows:By appropriate
selection of the ratio of turns, a transformer thus enables an alternating current (AC)
voltage to be "stepped up" by making Ns greater than Np, or "stepped down" by making
Ns less than Np.In the vast majority of transformers, the windings are coils wound around
a ferromagnetic core, air-core transformers being a notable exception.
Transformers range in size from a thumbnail-sized coupling transformer hidden inside a
stage microphone to huge units weighing hundreds of tons used to interconnect portions of
power grids. All operate on the same basic principles, although the range of designs is
wide. While new technologies have eliminated the need for transformers in some
electronic circuits, transformers are still found in nearly all electronic devices designed for
household ("mains") voltage. Transformers are essential for high-voltage electric power
transmission, which makes long-distance transmission economically practical.
A transformer is an electrical device that transfers energy from one circuit to another by
magnetic coupling with no moving parts. A transformer comprises two or more coupled
windings, or a single tapped winding and, in most cases, a magnetic core to concentrate
magnetic flux. A changing current in one winding creates a time-varying magnetic flux in
the core, which induces a voltage in the other windings. Michael Faraday built the first
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transformer, although he used it only to demonstrate the principle of electromagnetic
induction and did not foresee the use to which it would eventually be put.
FIG- 12 Transformer core
DC Motor
A DC motor is an electric motor that runs on direct current (DC) electricity. DC motors
were used to run machinery, often eliminating the need for a local steam engine or internal
combustion engine. DC motors can operate directly from rechargeable batteries, providing
the motive power for the first electric vehicles. Today DC motors are still found in
applications as small as toys and disk drives, or in large sizes to operate steel rolling mills
and paper machines. Modern DC motors are nearly always operated in conjunction with
power electronic devices.
Two important performance parameters of DC motors are the motor constants, Kv and
Km.
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FIG-13DC motor
DC motor
When a current passes through the coil wound around a soft iron core, the side of the
positive pole is acted upon by an upwards force, while the other side is acted upon by a
downward force. According to Fleming's left hand rule, the forces cause a turning effect on
the coil, making it rotate. To make the motor rotate in a constant direction, "direct current"
commutators make the current reverse in direction every half a cycle (in a two-pole motor)
thus causing the motor to continue to rotate in the same direction.
A problem with the motor shown above is that when the plane of the coil is parallel to the
magnetic field—i.e. when the rotor poles are 90 degrees from the stator poles—the torque
is zero. In the pictures above, this occurs when the core of the coil is horizontal—the
position it is just about to reach in the last picture on the right. The motor would not be
able to start in this position. However, once it was started, it would continue to rotate
through this position by momentum.
There is a second problem with this simple pole design. At the zero-torque position, both
commutator brushes are touching (bridging) both commutator plates, resulting in a short-
circuit. The power leads are shorted together through the commutator plates, and the coil is
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also short-circuited through both brushes (the coil is shorted twice, once through each
brush independently). Note that this problem is independent of the non-starting problem
above; even if there were a high current in the coil at this position, there would still be zero
torque. The problem here is that this short uselessly consumes power without producing
any motion (nor even any coil current.) In a low-current battery-powered demonstration
this short-circuiting is generally not considered harmful. However, if a two-pole motor
were designed to do actual work with several hundred watts of power output, this shorting
could result in severe commutator overheating, brush damage, and potential welding of the
brushes—if they were metallic—to the commutator. Carbon brushes, which are often used,
would not weld. In any case, a short like this is very wasteful, drains batteries rapidly and,
at a minimum, requires power supply components to be designed to much higher standards
than would be needed just to run the motor without the shorting.
The inside of an electric DC motor.
One simple solution is to put a gap between the commutator plates which is wider than the
ends of the brushes. This increases the zero-torque range of angular positions but
eliminates the shorting problem; if the motor is started spinning by an outside force it will
continue spinning. With this modification, it can also be effectively turned off simply by
stalling (stopping) it in a position in the zero-torque (i.e. commutator non-contacting) angle
range. This design is sometimes seen in homebuilt hobby motors, e.g. for science fairs and
such designs can be found in some published science project books. A clear downside of
this simple solution is that the motor now coasts through a substantial arc of rotation twice
per revolution and the torque is pulsed. This may work for electric fans or to keep a
flywheel spinning but there are many applications, even where starting and stopping are
not necessary, for which it is completely inadequate, such as driving the capstan of a tape
transport, or any instance where to speed up and slow down often and quickly is a
requirement. Another disadvantage is that, since the coils have a measure of self
inductance, current flowing in them cannot suddenly stop. The current attempts to jump the
opening gap between the commutator segment and the brush, causing arcing.
Even for fans and flywheels, the clear weaknesses remaining in this design—especially
that it is not self-starting from all positions—make it impractical for working use,
especially considering the better alternatives that exist. Unlike the demonstration motor
IEC-CET/2008-2012 Page 38
Currency Counting Machine with Fake Note Detection
above, DC motors are commonly designed with more than two poles, are able to start from
any position, and do not have any position where current can flow without producing
electromotive power by passing through some coil. Many common small brushed DC
motors used in toys and small consumer appliances, the simplest mass-produced DC
motors to be found, have three-pole armatures. The brushes can now bridge two adjacent
commutator segments without causing a short circuit. These three-pole armatures also have
the advantage that current from the brushes either flows through two coils in series or
through just one coil. Starting with the current in an individual coil at half its nominal
value (as a result of flowing through two coils in series), it rises to its nominal value and
then falls to half this value. The sequence then continues with current in the reverse
direction. This results in a closer step-wise approximation to the ideal sinusoidal coil
current, producing a more even torque than the two-pole motor where the current in each
coil is closer to a square wave. Since current changes are half those of a comparable two-
pole motor, arcing at the brushes is consequently less.
If the shaft of a DC motor is turned by an external force, the motor will act like a generator
and produce an Electromotive force (EMF). During normal operation, the spinning of the
motor produces a voltage, known as the counter-EMF (CEMF) or back EMF, because it
opposes the applied voltage on the motor. The back EMF is the reason that the motor when
free-running does not appear to have the same low electrical resistance as the wire
contained in its winding. This is the same EMF that is produced when the motor is used as
a generator (for example when an electrical load, such as a light bulb, is placed across the
terminals of the motor and the motor shaft is driven with an external torque). Therefore,
the total voltage drop across a motor consists of the CEMF voltage drop, and the parasitic
voltage drop resulting from the internal resistance of the armature's windings.
Speed control
Generally, the rotational speed of a DC motor is proportional to the voltage applied to it,
and the torque is proportional to the current. Speed control can be achieved by variable
battery tappings, variable supply voltage, resistors or electronic controls. The direction of a
wound field DC motor can be changed by reversing either the field or armature
connections but not both. This is commonly done with a special set of contactors (direction
contactors).The effective voltage can be varied by inserting a series resistor or by an
IEC-CET/2008-2012 Page 39
Currency Counting Machine with Fake Note Detection
electronically controlled switching device made of thyristors, transistors, or, formerly,
mercury arc rectifiers.
In a circuit known as a chopper, the average voltage applied to the motor is varied by
switching the supply voltage very rapidly. As the "on" to "off" ratio is varied to alter the
average applied voltage, the speed of the motor varies. The percentage "on" time
multiplied by the supply voltage gives the average voltage applied to the motor. Therefore,
with a 100 V supply and a 25% "on" time, the average voltage at the motor will be 25 V.
During the "off" time, the armature's inductance causes the current to continue through a
diode called a "flyback diode", in parallel with the motor. At this point in the cycle, the
supply current will be zero, and therefore the average motor current will always be higher
than the supply current unless the percentage "on" time is 100%. At 100% "on" time, the
supply and motor current are equal. The rapid switching wastes less energy than series
resistors. This method is also called pulse-width modulation (PWM) and is often controlled
by a microprocessor. An output filter is sometimes installed to smooth the average voltage
applied to the motor and reduce motor noise.
Since the series-wound DC motor develops its highest torque at low speed, it is often used
in traction applications such as electric locomotives, and trams. Another application is
starter motors for petrol and small diesel engines. Series motors must never be used in
applications where the drive can fail (such as belt drives). As the motor accelerates, the
armature (and hence field) current reduces. The reduction in field causes the motor to
speed up until it destroys itself. This can also be a problem with railway motors in the
event of a loss of adhesion since, unless quickly brought under control, the motors can
reach speeds far higher than they would do under normal circumstances. This can not only
cause problems for the motors themselves and the gears, but due to the differential speed
between the rails and the wheels it can also cause serious damage to the rails and wheel
treads as they heat and cool rapidly. Field weakening is used in some electronic controls to
increase the top speed of an electric vehicle.
The simplest form uses a contactor and field-weakening resistor; the electronic control
monitors the motor current and switches the field weakening resistor into circuit when the
motor current reduces below a preset value (this will be when the motor is at its full design
speed). Once the resistor is in circuit, the motor will increase speed above its normal speed
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Currency Counting Machine with Fake Note Detection
at its rated voltage. When motor current increases, the control will disconnect the resistor
and low speed torque is made available.
One interesting method of speed control of a DC motor is the Ward Leonard control. It is a
method of controlling a DC motor (usually a shunt or compound wound) and was
developed as a method of providing a speed-controlled motor from an AC supply, though
it is not without its advantages in DC schemes. The AC supply is used to drive an AC
motor, usually an induction motor that drives a DC generator or dynamo. The DC output
from the armature is directly connected to the armature of the DC motor (sometimes but
not always of identical construction). The shunt field windings of both DC machines are
independently excited through variable resistors. Extremely good speed control from
standstill to full speed, and consistent torque, can be obtained by varying the generator
and/or motor field current. This method of control was the de facto method from its
development until it was superseded by solid state thyristor systems.
It found service in almost any environment where good speed control was required, from
passenger lifts through to large mine pit head winding gear and even industrial process
machinery and electric cranes. Its principal disadvantage was that three machines were
required to implement a scheme (five in very large installations, as the DC machines were
often duplicated and controlled by a tandem variable resistor). In many applications, the
motor-generator set was often left permanently running, to avoid the delays that would
otherwise be caused by starting it up as required. Although electronic (thyristor) controllers
have replaced most small to medium Ward-Leonard systems, some very large ones
(thousands of horsepower) remain in service. The field currents are much lower than the
armature currents, allowing a moderate sized thyristor unit to control a much larger motor
than it could control directly. For example, in one installation, a 300 amp thyristor unit
controls the field of the generator. The generator output current is in excess of 15,000
amperes, which would be prohibitively expensive (and inefficient) to control directly with
thyristors.
INFRARED SENSOR
In this IR detector and transmitter circuit the IC 555 is working under astable mode. The
pin 4 i.e. reset pin is when grounded via IR receiver the pin 3 output is low.
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FIG-14 Infra red sensor with circuitry
As soon as the IR light beam transmitted is obstructed, a momentary pulse actuates the
relay output (or LED).The IR transmitter is simple series connected resistor network from
battery. The timing capacitor connected to pin 2 and ground can varied as per requirement
Switched-mode power supply
A switched-mode power supply (switching-mode power supply, SMPS, or switcher) is an
electronic power supply that incorporates a switching regulator to convert electrial power
efficiently. Like other power supplies, an SMPS transfers power from a source like the
electrical powergrid to a load (such as a personal computer) while
converting voltage and current characteristics. An SMPS is usually employed to efficiently
provide a regulated output voltage, typically at a level different from the input voltage.
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Unlike a linear power supply, the pass transistor of a switching mode supply continually
switches between low-dissipation, full-on and full-off states, and spends very little time in
the high dissipation transitions (which minimizes wasted energy). Ideally, a switched-
mode power supply dissipates no power
FIG-15 Switched mode power supply circuitry
Unlike a linear power supply, the pass transistor of a switching mode supply continually
switches between low-dissipation, full-on and full-off states, and spends very little time in
the high dissipation transitions (which minimizes wasted energy). Ideally, a switched-
mode power supply dissipates no power. Voltage regulation is achieved by varying the
ratio of on-to-off time. In contrast, a linear power supply regulates the output voltage by
continually dissipating power in the pass transistor. This higher power conversion
efficiency is an important advantage of a switched-mode power supply. Switched-mode
power supplies may also be substantially smaller and lighter than a linear supply due to the
smaller transformer size and weight.
Switching regulators are used as replacements for the linear regulators when higher
efficiency, smaller size or lighter weight are required. They are, however, more
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complicated, their switching currents can cause electrical noise problems if not carefully
suppressed, and simple designs may have a linear regulator provides the desired
output voltage by dissipating excess power in ohmic losses (e.g., in a resistor or in the
collector–emitter region of a pass transistor in its active mode). A linear regulator regulates
either output voltage or current by dissipating the excess electric power in the form of heat,
and hence its maximum power efficiency is voltage-out/voltage-in since the volt difference
is wasted. In contrast, a switched-mode power supply regulates either output voltage or
current by switching ideal storage elements, like inductors and capacitors, into and out of
different electrical configurations. Ideal switching elements (e.g., transistors operated
outside of their active mode) have no resistance when "closed" and carry no current when
"open", and so the converters can theoretically operate with 100% efficiency (i.e., all input
power is delivered to the load; no power is wasted as dissipated heat).
For example, if a DC source, an inductor, a switch, and the corresponding electrical
ground are placed in series and the switch is driven by a square wave, the peak-to-peak
voltage of the waveform measured across the switch can exceed the input voltage from the
DC source. This is because the inductor responds to changes in current by inducing its own
voltage to counter the change in current, and this voltage adds to the source voltage while
the switch is open.
If a diode-and-capacitor combination is placed in parallel to the switch, the peak voltage
can be stored in the capacitor, and the capacitor can be used as a DC source with an output
voltage greater than the DC voltage driving the circuit. This boost converter acts like
a step-up transformer for DC signals. A buck–boost converter works in a similar manner,
but yields an output voltage which is opposite in polarity to the input voltage.
Other buck circuits exist to boost the average output current with a reduction of voltage.
In an SMPS, the output current flow depends on the input power signal, the storage
elements and circuit topologies used, and also on the pattern used (e.g. pulse-width
modulation with an adjustable duty cycle) to drive the switching elements. Typically,
the spectral density of these switching waveforms has energy concentrated at relatively
high frequencies. As such, switching transients, like ripple, introduced onto the output
waveforms can be filtered with small LC filters.
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Advantages and disadvantages
The main advantage of this method is greater efficiency because the switching transistor
dissipates little power when it is outside of its active region (i.e., when the transistor acts
like a switch and either has a negligible voltage drop across it or a negligible current
through it). Other advantages include smaller size and lighter weight (from the elimination
of low frequency transformers which have a high weight) and lower heat generation due to
higher efficiency.
Disadvantages include greater complexity, the generation of high-amplitude, high-
frequency energy that the low-pass filter must block to avoid electromagnetic
interference (EMI), a ripple voltage at the switching frequency and the harmonic
frequencies thereof. Very low cost SMPSs may couple electrical switching noise back onto
the mains power line, causing interference with A/V equipment connected to the same
phase. Non-power-factor-corrected SMPSs also cause harmonic distortion
Battery
An electrochemical battery - or, more precisely, a "cell" - is a device in which the reaction
between two substances can be made to occur in such a way that some of the chemical
energy is converted to useful electricity. When the cell can only be used once, it is called a
"primary" cell. When the chemical reaction can be reversed repeatedly by applying
electrical energy to the cell, it is called a "secondary" cell and can be used in an
accumulator or "storage" battery.
Certain cells are capable of only a few charge-discharge cycles and are, therefore,
technically "secondary" cells. Such is the case with certain silver oxide-zinc batteries.
These batteries are not capable of the repeated cycling required of a satellite battery
system, and are, therefore, considered to be "rechargeable primary" rather than storage
batteries. To define a battery in another way, it is an arrangement whereby an
"electrochemical" reaction can be made to take place so that the "electrical" part of the
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reaction proceeds via the metallic path of the external circuit, while the "chemical" part of
the reaction occurs via ionic conduction through electrolyte.
The type of chemical reaction that can be used in an electrochemical cell is known as an
"oxidation-reduction" reaction - a reaction in which one chemical species gives electrons to
another. By separating the two species and controlling the flow of ions between them,
battery engineers make devices in which essentially all of these electrons can be made to
flow through an external circuit, thereby converting most of the chemical energy to
electrical energy during the discharge of the cell.
Some of the components common to all cells are:
1. The "cathode" or "positive" electrode, which consists of a mass of "electron-receptive"
chemical held in intimate contact with a metallic "plate" through which the electrons
arrive from the external circuit.
2. The "anode" or "negative" electrode, which consists of another chemical which readily
gives up electrons - an "electron donor" - similarly held in close contact with a metallic
member through which electrons can be conducted to the external circuit.
3. The "electrolyte," usually a liquid solution that permits the transfer of mass necessary
to the overall reaction. This movement takes place by "migration" of "ions" - positively
or negatively charged molecular fragments - from anode to cathode and from cathode
FIG- 16 Battery
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A schematic diagram of these basic cell elements is shown above. The cell is shown
connected to a load - representing the discharge reaction. Charging is accomplished by
connecting an electrical source in place of the load, thereby reversing the entire process.
UV Detector
UV detectors function on the capacity of many compounds to absorb light in the
wavelength range 180 to 350 nm. The sensor cell usually consists of a cylindrical cavity
about 1 mm I.D and a few mm long, having a capacity that ranges from about two micro-
liters to eight micro-liters.
FIG- 17 UV detector
Light from a UV light sources passes through the sensor onto a photoelectric cell, the out
put from which is electronically modified and presented on a potentiometric recorder, a
computer screen, or printer. By interposing a monochrometer between the light source and
the cell, light of a specific wavelength can be selected for detection and, thus, improve the
detector selectivity.
Alternatively a broad band light source can be used and the light after passing through the
cell can be optically dispersed by prism or grating and allowed to fall onto a diode array.
By monitoring a specific diode, the detector can be made specific for those substances that
absorb at that particular wavelength. If the output from all the diodes is scanned then a UV
absorption spectrum can be obtained to aid in solute identification. The fixed wavelength
UV detector has a sensitivity of about 1 x 10-8 g per ml at a signal to noise ratio of two are
the UV detector (fixed and variable wavelength) the electrical conductivity detector, the
fluorescence detector and the refractive index detector. These detectors are employed in
over 95% of all LC analytical applications. These four detectors will be described and for
those readers requiring more information on detectors are referred to Liquid
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Currency Counting Machine with Fake Note Detection
Chromatography Detectors.
The UV Detector The UV detector is by far the most popular and useful LC detector that is
available to the analyst at this time. This is particularly true if multi-wavelength
technology is included in this class of detectors. Although the UV detector has some
definite limitations (particularly for the detection of non polar solutes that do not possess a
UV chromaphores) it has the best
CAUTIONS
(1) Cautions
1. The devices are UV light LEDs. The LED during operation radiates intense UV light,
which precautions must be taken to prevent looking directly at the UV light with
unaided eyes.
2. Do not look directly into the UV light or look through the optical system. When there
is a possibility to receive the reflection of light, protect by using the UV light
protective glasses so that light should not catch one’s eye directly.
3. Put the caution label on the cardboard box.
(2) Lead Forming
1. When forming leads, the leads should be bent at a point at least 3mm from the base of
the lead.
2. Do not use the base of the lead frame as a fulcrum during lead forming.
3. Lead forming should be done before soldering.
4. Do not apply any bending stress to the base of the lead. The stress to the base may
damage the LED’s characteristics or it may break the LEDs.
5. When mounting the LEDs onto a printed circuit board, the holes on the circuit board
should be exactly aligned with the leads of the LEDs. If the LEDs are mounted with
stress at the leads, it causes deterioration of the lead and this will degrade the LEDs.
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Currency Counting Machine with Fake Note Detection
(3) Storage
The LEDs should be stored at 30°C or less and 70%RH or less after being shipped from
Nichia and the storage life limits are 3 months. If the LEDs are stored for 3 months or
more, they can be stored for a year in a sealed container with a nitrogen atmosphere and
moisture absorbent material. Nichia LED leads are comprised of a gold plated Iron alloy.
The gold surface may be affected by environments which contain corrosive gases and so
on. Please avoid conditions which may cause the LED to corrode, tarnish or discolor. This
corrosion or discoloration may cause difficulty during soldering operations. It is
recommended that the LEDs be used as soon as possible. Please avoid rapid transitions in
ambient temperature, especially, in high humidity environments where condensation can
occur.
(4) Static Electricity
Static electricity or surge voltage damages the LEDs. It is recommended that a wrist band
or an anti-electrostatic glove be used when handling the LEDs. All devices, equipment and
machinery must be properly grounded. It is recommended that measure be taken against
surge voltage to the equipment that mounts LEDs. When inspecting the final products in
which LEDs were assembled, it is recommended to check whether the assembled LEDs are
damaged by static electricity or not. It is easy to find static-damaged LEDs by a light-on
test or a VF test at a lower current (below 1mA is recommended). The LEDs should be
used the light detector etc. when testing the light-on. Do not stare into the LEDs when
testing. Damaged LEDs will show some unusual characteristics such as the forward
voltage becomes lower, or the LEDs do not light at the low current. Criteria : (VF > 2.0V
at IF=0.5mA)
(6) Heat Generation
Thermal design of the end product is of paramount importance. Please consider the heat
generation of the LED when making the system design. The coefficient of temperature
increase per input electric power is affected by the thermal resistance of the circuit board
and density of LED placement on the board, as well as other components. It is necessary to
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Currency Counting Machine with Fake Note Detection
avoid intense heat generation and operate within the maximum ratings given in this
specification. The operating current should be decided after considering the ambient
maximum temperature of LEDs.
(7) Cleaning
It is recommended that isopropyl alcohol be used as a solvent for cleaning the LEDs.
When using other solvents, it should be confirmed beforehand whether the solvents will
dissolve the glass or not. Freon solvents should not be used to clean the LEDs because of
worldwide regulations. Do not clean the LEDs by the ultrasonic. When it is absolutely
necessary, the influence of ultrasonic cleaning on the LEDs depends on factors such as
ultrasonic power and the assembled condition. Before cleaning, a pre-test should be done
to confirm whether any damage to the LEDs will occur.
(8) Safety Guideline for Human Eyes
In 1993, the International Electric Committee (IEC) issued a standard concerning laser
product safety. Since then, this standard has been applied for diffused light sources (LEDs)
as well as lasers. In 1998 IEC 60825-1 Edition 1.1 evaluated the magnitude of the light
source. In 2001 IEC 60825-1 Amendment 2 converted the laser class into 7 classes for end
products. Components are excluded from this system. Products which contain visible
LEDs are now classified as class 1. Products containing UV LEDs are class 1M. Products
containing LEDs can be classified as class 2 in cases where viewing angles are narrow,
optical manipulation intensifies the light, and/or theenergy emitted is high. For these
systems it is recommended to avoid long term exposure. It is also recommended to follow
the IEC regulations regarding safety and labeling of products.
(9) Others
NSHU550B complies with RoHS Directive. This LED also emits visible light. Please take
notice of visible light spectrum, in case you use this LED as light source of sensors etc.
The LEDs described in this brochure are intended to be used for ordinary electronic
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Currency Counting Machine with Fake Note Detection
equipment (such as office equipment, communications equipment, measurement
instruments and household appliances).
Consult Nichia’s sales staff in advance for information on the applications in which
exceptional quality and reliability are required, particularly when the failure or malfunction
of the LEDs may directly. Jeopardize life or health (such as for airplanes, aerospace,
submersible repeaters, nuclear reactor control systems, automobiles, traffic control
equipment, life support systems and safety devices).User shall not reverse engineer by
disassembling or analysis of the LEDs without having the prior written consent of Nichia.
When defective LEDs are found, User shall inform to Nichia directly before disassembling
or analysis.The formal specifications must be exchanged and signed by both parties before
large volume purchase begins. The appearance and specifications of the product may be
modified for improvement without
ULN2003
ULN2003 is a high voltage and high current Darlington array IC. It contains seven open
collector darlington pairs with common emitters. A darlington pair is an arrangement of
two bipolar transistors. ULN2003 belongs to the family of ULN200X series of ICs.
Different versions of this family interface to different logic families.ULN2003 are for 5V
TTL, CMOS logic devices. These ICs are used when driving a wide range of loads and are
used as relay drivers, display drivers, line drivers etc.
ULN2003 is also commonly used while driving Stepper Motors. The ULN2003 is a
monolithic high voltage and high current Darlington transistor arrays. It consists of seven
NPN darlington pairs that features high voltage outputs with common-cathode clamp diode
for switching inductive loads. The collector-current rating of a single darlington pair is
500mA. The darlington pairs may be paralleled for higher current capability. Applications
include relay drivers, hammer drivers, lamp drivers, display drivers(LED gas
discharge),line drivers, and logic buffers. The ULN2003 has a 2.7kΩ series base resistor
for each darlington pair for operation directly with TTL or 5V CMOS devices.
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FIG-18 ULN2003 Darlington using high-power stepper motor ..
FEATURES
500mA rated collector current(Single output)
High-voltage outputs: 50V
Inputs compatible with various types of logic.
Relay driver application
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4. CODES
$mod51
org 0000h
mov p1,#0ffh
mov p3,#0h
mov p2,#0h
mov p0,#0h
mov r7,#02h
mov r6,#0h
mov r5,#0h
mov r4,#02h
setb p3.0
abc:jb p3.0,abc
setb p3.1
setb p3.2
setb p3.3
setb p3.4
setb p3.5
setb p3.6
clr p3.7
acall wel_lcd
ljmp main
wel_lcd:
mov a,#38h
acall comnwrt
acall delay
mov a,#0ch
acall comnwrt
acall delay
mov a,#01h
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acall comnwrt
acall delay
mov a,#06h
acall comnwrt
acall delay
mov a,#80h
acall comnwrt
acall delay
mov a,#'R'
acall datawrt
acall delay
mov a,#'B'
acall datawrt
acall delay
mov a,#'I'
acall datawrt
acall delay
mov a,#' '
acall datawrt
acall delay
mov a,#'N'
acall datawrt
acall delay
mov a,#'O'
acall datawrt
acall delay
mov a,#'T'
acall datawrt
acall delay
mov a,#'E'
acall datawrt
acall delay
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mov a,#'I'
acall datawrt
acall delay
mov a,#'R'
acall datawrt
acall delay
mov a,#' '
acall datawrt
acall delay
mov a,#'C'
acall datawrt
acall delay
mov a,#'O'
acall datawrt
acall delay
mov a,#'U'
acall datawrt
acall delay
mov a,#'N'
acall datawrt
acall delay
mov a,#'T'
acall datawrt
acall delay
mov a,#'I'
acall datawrt
acall delay
mov a,#'N'
acall datawrt
acall delay
mov a,#'G'
acall datawrt
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acall delay
ret
main:
jb p3.0,fdf
cpl p3.1
fdf:jb p1.0,aa
ljmp anion
aa:jb p1.1,bb2
ljmp uv
bb2:jb p1.2,cc2
ljmp tmer
cc2:jb p1.3,tter
ljmp speed
tter:mov a,#1ch
acall comnwrt
acall delay
acall delay
acall delay
acall delay
ljmp main
anion:
cjne r6,#01h,wqw
mov r6,#0h
ljmp qwq
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Currency Counting Machine with Fake Note Detection
wqw:
inc r6
acall wel_lcd
mov a,#0c0h
acall comnwrt
acall delay
mov a,#'A'
acall datawrt
acall delay
mov a,#':'
acall datawrt
acall delay
mov a,#'O'
acall datawrt
acall delay
mov a,#'N'
acall datawrt
acall delay
setb p3.2
ljmp main
qwq:
acall wel_lcd
mov a,#'A'
acall datawrt
acall delay
mov a,#':'
acall datawrt
acall delay
mov a,#'O'
acall datawrt
acall delay
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mov a,#'F'
acall datawrt
acall delay
mov a,#'F'
acall datawrt
acall delay
clr p3.2
acall delay2
ljmp wel_lcd
uv:
cjne r5,#01h,wqq
mov r5,#0h
ljmp qww
wqq:
inc r5
mov a,#01h
acall comnwrt
acall delay
mov a,#'U'
acall datawrt
acall delay
mov a,#'V'
acall datawrt
acall delay
mov a,#':'
acall datawrt
acall delay
mov a,#'O'
acall datawrt
acall delay
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mov a,#'N'
acall datawrt
acall delay
setb p3.3
acall delay2
ljmp wel_lcd
qww:mov a,#01h
acall comnwrt
acall delay
mov a,#'U'
acall datawrt
acall delay
mov a,#'V'
acall datawrt
acall delay
mov a,#':'
acall datawrt
acall delay
mov a,#'O'
acall datawrt
acall delay
mov a,#'F'
acall datawrt
acall delay
mov a,#'F'
acall datawrt
acall delay
clr p3.3
acall delay2
ljmp wel_lcd
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speed:inc r7
cjne r7,#03h,asd
mov r7,#0h
mov a,#01h
acall comnwrt
acall delay
mov a,#'S'
acall datawrt
acall delay
mov a,#'P'
acall datawrt
acall delay
mov a,#'E'
acall datawrt
acall delay
mov a,#'E'
acall datawrt
acall delay
mov a,#'D'
acall datawrt
acall delay
mov a,#':'
acall datawrt
acall delay
mov a,#'3'
acall datawrt
acall delay
setb p3.7
setb p3.6
setb p3.5
acall delay2
ljmp wel_lcd
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asd:cjne r7,#02h,dsad
mov a,#01h
acall comnwrt
acall delay
mov a,#'S'
acall datawrt
acall delay
mov a,#'P'
acall datawrt
acall delay
mov a,#'E'
acall datawrt
acall delay
mov a,#'E'
acall datawrt
acall delay
mov a,#'D'
acall datawrt
acall delay
mov a,#':'
acall datawrt
acall delay
mov a,#'2'
acall datawrt
acall delay
setb p3.5
setb p3.6
clr p3.7
acall delay2
ljmp wel_lcd
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dsad:cjne r7,#01h,rwe
mov a,#01h
acall comnwrt
acall delay
mov a,#'S'
acall datawrt
acall delay
mov a,#'P'
acall datawrt
acall delay
mov a,#'E'
acall datawrt
acall delay
mov a,#'E'
acall datawrt
acall delay
mov a,#'D'
acall datawrt
acall delay
mov a,#':'
acall datawrt
acall delay
mov a,#'1'
acall datawrt
acall delay
setb p3.5
clr p3.6
clr p3.7
acall delay2
ljmp wel_lcd
rwe:cjne r7,#0h,gfd
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mov r7,#02h
acall delay1
ljmp main
gfd:ljmp main
tmer:ljmp main
comnwrt:
mov p2,a
clr p0.0
setb p0.1
clr p0.1
ret
datawrt:
mov p2,a
setb p0.0
setb p0.1
clr p0.1
RET
delay:MOV R2,#90
MOV R1,#162
TT1: DJNZ R1,TT1
DJNZ R2,TT1
RET
delay1:MOV R3,#4
MOV R2,#132
MOV R1,#116
TT11: DJNZ R1,TT11
DJNZ R2,TT11
DJNZ R3,TT11
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ret
delay2:MOV R3,#15
MOV R2,#16
MOV R1,#221
TT12: DJNZ R1,TT12
DJNZ R2,TT12
DJNZ R3,TT12
RET
End
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5. DISCUSSION OF RESULTS
The idea was to create an currency note counting machine with fake detection which
would circumvent the manual detection involved in detecting fake currency. Currency
created by colour copier or printer produces an image tht rest on the surface of paper that
can easily be seen when uv light is placed over it. Real notes notes are printed on optical
fiber paper fake ones on thick paper made of bamboo pulp. Money Counter & Counterfeit
Note Detector offers exclusive peace of mind. Provided with a top mounted numeric count
display screen as well as a detachable LCD display for customers, this helps keep your
counts accurate and quick. With built in UV and Thread detection, this unit prevents any
fakes from being passed on to you.
Detecting fake bills just by looking at it, is not exactly the most efficient or even reliable
way of knowing for sure if a bill is fake. Counterfeit notes are becoming more difficult to
detect with the naked eye, that's were advanced machines like this 2-in-1 multi-currency
money counter & detector comes in. This is a professional grade unit being offered
exclusively to our customers at a low factory-direct wholesale price, making this new
money counter and counterfeit detector a must-have-product for any small, medium or
large business.
FICN (Fake Indian Currency Note) is a term used by officials and media to refer
fake Indian currency notes circulated in the Indian economy. The fake notes of latest
Gandhi series are so perfect that it is hard to identify if it is fake or not. Though fake
currency is being printed with precision, CID sleuths say that they can be detected with
some effort. Currency printed by local racketeers can be detected easily as they use
photographic method, hand engraved blocks, lithographic process and computer colour
scanning.In counterfeit notes the watermark is made by using opaque ink, painting with
white solution, stamping with a dye engraved with the picture of Mahatma Gandhi. Then
the gangs apply oil, grease or wax to give the picture a translucent feel. In genuine notes
the security thread is incorporated into the paper at the time of manufacture.
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Currency Counting Machine with Fake Note Detection
But in fake notes, the security thread is imitated by drawing a line with a pencil or by
printing a line with grey ink or by using aluminium thread while pasting two thin sheets of
paper. Forgers find it difficult to reproduce the same shape of individual numbers again
and again with accuracy. The alignment of figures is also difficult to maintain. Spreading
of ink, smaller or bigger number, inadequate gaps, and different alignments in numbers
should be regarded with suspicion. In counterfeit notes, the printed lines will be broken
and there may also be ink smudges. Basic banknote counters provide a total count of the
notes in the supply hopper.
More advanced counters can identify different bill denominations to provide a total
currency value of mixed banknotes, including those that are upside down. Some banknote
counters can also detect counterfeit bills either magnetically and/or using backlights. Black
light (UV) based detectors exploit the fact that in many countries, real banknotes have
fluorescent symbols on them that only show under a black light. Also, the paper used for
printing money does not contain any of the brightening agents which make commercially
available papers fluoresce under black light. Both features make counterfeit notes both
easier to detect and more difficult to successfully produce.
A stack of bills are placed in a compartment of the machine, and then one bill at a time is
mechanically pulled through the machine. By counting the number of times a beam of light
is interrupted, the machine can count the bills. By comparing an image of each bill
to pattern recognition criteria, the machine can figure out how much genuine money was
placed in the compartment.
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6. CONCLUSION
Fake currency poses a grave threat to national security and could also result in economic
destabilization. According to intelligence agencies, anti-national elements and crime
syndicates open several accounts and use the ATMs to deposit the fake currencies. If they
see that the amount has been credited to their account, they continue to deposit fake
money. If the amount is not credited they know that their game is up and no longer operate
that account. In the past, it was easy to detect fake currencies as they were printed by
people with limited expertise, using crude facilities. But with the forgers attaining a high
level of sophistication, it is increasingly difficult to detect fake notes.
The situation is scary, particularly after the recent detection of Rs 400 million from the
State Bank of India chest at one of its branches in the northern Uttar Pradesh state. Not
only the counterfeit notes were of high quality, but they also had the same serial numbers
as the genuine notes kept at the bank. It is estimated that around 1,69,000 crores of fake
rupees are in circulation all over India. Both Banks and Government are in a denial mode,
because probably they do not know what to do.
India has become the victim of another kind of terrorism from its neighbour, Pakistan. It is
economic terrorism in printing and circulating counterfeit Indian notes. The Pakistani
intelligence agency, ISI’s role in printing and circulation of fake Indian currency notes has
never been a secret.On its insistence, Pakistan Government has imported additional
currency-standard printing paper from companies located in London to pursue its nefarious
designs in India. Of late, Pakistan has been procuring currency-standard printing paper in
huge quantities from London-based companies much higher than normal requirement of
the country for printing its own currency. It is diverting it, to print fake Indian currency
notes. It is believed that Pakistan Government printing press in Quetta (Baluchistan)
Karachi’s security press, and two other presses in Lahore and Peshawar, are being used to
print out counterfeit Indian currency.
The ISI has, been using Pakistan International Airlines (PIA) to transport counterfeit
currency to its conduits in Nepal, Bangladesh and Sri Lanka. The modus operandi of the
ISI was revealed by two Nepali counterfeit currency traffickers who were arrested by
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Currency Counting Machine with Fake Note Detection
Thailand police sometimes back. During interrogation, the accused disclosed that they
were working for a prominent Nepali businessman. The fact that Nepali territory is being
used by Pakistanis to smuggle counterfeit currency is well known. The first such expose
was made when Pakistani diplomats were caught distributing fake Indian currency notes.
One Naushad Alam Khan, arrested in Dhaka on April 24, 2008, with fake Indian currency
notes worth Rs 50 lakh admitted his direct link with HuJI (Bangladesh) chief Mufti Abdul
Hannan. It was found that both Khan and Hannan had fought for Taliban in Afghanistan.
Fake Indian currency notes racket is being carried out by using the network of underworld
kingpin Dawood Ibrahim, not only in India but also in Sri Lanka, Bangladesh and Nepal in
close association with different terror outfits, according to one intelligence report. With Sri
Lanka, Nepal and Bangladesh being active partners, with India in probing fake Indian
currency notes (FICN) related cases, it is safe to assume that so far as the fake currency in
India is concerned, its source is Pakistan.Delhi police claims, to have busted a major ISI
network, sometimes back, which was reportedly being used to pushing fake currency into
our country. Three arrested men, by name, Nayeem, Wasim and Mohammed Muslim, have
revealed that Thar Express, so called, friendship train, running between Munnabao in
Pakistan and Jodhpur in Rajasthan, was being used to smuggle fake currency into India .
Investigation, uncovered, that the fake currency was arranged in Dubai. Fake currency to
the extent of Rs 33 lakh was seized from them.
They have confirmed that the Indian currency is printed in Pakistan and illegally pushed in
India through Nepal, Bangladesh, Sri Lanka, Malaysia and Thailand. The menace of finely
printed currency has achieved new heights, that quite often; the customers do get fake
currencies through ATMs. The worst is that when they approach banks with the complain
of receiving a fake note, bank official impound the notes. As per the law of land, the bank
should lodge an FIR with police, which would investigate the source of the fake currency.
Banks obviously have not been to cope with the problem. According to one Government
committee estimate, counterfeit currency amounting to Rs 169,000 crore is floating around
in the Indian financial system. This has been denied by the Reserve Bank of India. From
real estate transactions to ordinary grocery shopping, paying to sources and terrorist’s
expenses, these bogus notes are being used. Even if this figure is taken 20 to 25 per cent, as
correct, it is still a huge amount, and sufficient to damage India’s economy. “In 2008, the
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Currency Counting Machine with Fake Note Detection
CBI registered 13 cases having international/ inter-State ramifications relating to the
recovery/ seizure of fake Indian currency notes,”
According to the National Crime Record Bureau (NCRB), between January and August
2008, 1,170 cases had been registered across the country in connection with fake currency.
Bogus notes with a face value of Rs 3.63 crore had been seized. NCRB data shows 2,204
such cases were reported in 2007.Investigations into the Mumbai 26/11 attacks have
revealed that a large part of the money to fund the terror operation were obtained through
fake currency rackets and hawala channels.It is also believed that Pakistan’s Inter Services
Intelligence raises Rs 1,800 crore (Rs 18 billion) annually to fund terror operations and that
a major chunk of this amount comes in through fake currency rackets.
Intelligence sources believe that Rs 30 lakh of the Rs 50 lakh spent, on the attack on the
Indian Institute of Science, Bengaluru, in December 2005 was obtained through the fake
currency racket. This is big menace, which should be tackled with no holds barred, even if
it means walking with the devil till we have decimated this problem. It is rightly said, that
the poor of the world, cannot be made richer by redistribution of wealth. But, there are
some, who seek a short cut, to riches through crime and use of counterfeit currency.
Criminals believe, that whatever is worth doing is worth doing for the money.
Nevertheless, the truth is that the wealth is the product of industry, ambition, character and
untiring effort. The Special Task Force, (STF) of Uttar Pradesh, last year claimed to have
busted a major international racket involved, in supply of fake currency notes.
It seized counterfeit Indian currency worth a face value of Rs 16 lakh. The gang leader,
arrested in Lucknow with three of his aides, has confessed to have pumped into circulation
over Rs 2 crore in counterfeit currency in India in about two months. The gang members
arrested have been identified as Suhail Singh alias Ram Shanker Singh of Sikahira locality
under Khodare police station of Gonda-the gang leader-along with Sharma Paswan, Vinod
Kumar Misra and Sanjay Kumar Patel, all natives of Champaran in Bihar.
The gang was using a set of six women couriers from Champaran in Bihar and another set
of four hailing from Nepal. The fake currency notes had a different serial number. It
showed, that they had not merely been printed from a scanned image of a genuine note by
using coloured scanners and printers. In case the miscreants scan a genuine note and print
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Currency Counting Machine with Fake Note Detection
copies of it, the serial number of such counterfeit currency notes remain the same. Putting
a different serial number on each note explains that the counterfeit currency was being
printed at a very large scale.During interrogation, the accused revealed that the counterfeit
currency notes travelled to Uttar Pradesh from Nepal from two different routes: From
Nepal to UP via Bihar and directly to UP particularly through Sidhartnagar and
Maharajganj route. A Rs 1,000 denomination note was bought at the rate of Rs 500 to Rs
600 each while the Rs 500 denomination was bought for Rs 300 to Rs 400 each.
This whole ideology around economic terrorism? What is this guy serious or has India just
not had media attention for a while! And why would Pakistan want to effect the Indian
economy it does not make sense? The paper this stuff is printed on it worth too much to
allocate and even if they did print the notes it would take a shed load of an amount to
destabilise a economy. Take the example of England the amount of fake currency here is
ridiculous but it never has made news due to the amount it would take before and action
would be required. So take my advice and report something interesting such as India being
used by America and the uk to take control of all world matters and have total control of
individual states.
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7. APPLICATIONS
Bank & financial Institution
Hospitals.
Schools & colleges.
Hotels & restaurants.
Shopping malls.
Indian railways.
Airport authority.
Other transport services.
Retail outlets & showrooms
Corporate
Co-operatives
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Currency Counting Machine with Fake Note Detection
8. APPENDIX
In this section, we touch upon a few things which may prove to be beneficial to avid
readers and who wish to take this idea a step further.
Microcontroller Interfacing Techniques:
Micro-controllers are useful to the extent that they communicate with other devices, such
as sensors, motors, switches, keypads, displays, memory and even other micro-controllers.
Many interface methods have been developed over the years to solve the complex problem
of balancing circuit design criteria such as features, cost, size, weight, power consumption,
reliability, availability, manufacturability. Many microcontroller designs typically mix
multiple interfacing methods. In a very simplistic form, a micro-controller system can be
viewed as a system that reads from (monitors) inputs, performs processing and writes to
(controls) outputs.
Interfacing relay to microcontroller
A relay is an electrical switch that opens and closes under the 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. Because a relay is able to control an output circuit of higher
power than the input circuit, it can be considered to be, in a broad sense, a form of an
electrical amplifier.
Relay 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 approximately 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. Most 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.
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9. REFERENCES
[1] Fake notes and its detection techniques using 89C51.Undergraduate final project no.
02010741/ELK/2005
[2] www.atmel.com
[3] en.wikipedia.org
[4] www.proteus.software.informer.com
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