Post on 22-Feb-2015
transcript
This is to certify that the project of
Digital Object Counter (Main Circuit)
Contains the bonafied works of
Mr. Kaustubh Shridhar Gurjar
Who has worked on the project and completed the same
In the academic year 2004-05.
His project work is in Electronics Discipline as per
The Maharashtra State Board of Secondary & Higher Secondary
Education, Pune; Syllabus.
Principal Head of the
Department
Project Guide
It adds to my pleasure to acknowledge the persons who have helped me
while the project work was in progress!
First of all, I am thankful to Mr. D. S. Vidyasagar sirMr. D. S. Vidyasagar sir, our Project Guide,
who has helped us in bringing out this project in present status!
Our Mrs. V. N. Oke madamMrs. V. N. Oke madam, who has also encouraged us and helped us
during completion of this project, for we are also thankful to her.
I am grateful to our Head of the department, Prof. Mrs. V. B. RajurkarProf. Mrs. V. B. Rajurkar
madammadam, for, for providing us the facility of excellent lab instruments and
relevant accessories.
I am also deeply grateful to our Hon. Principal Prof. D. V. Rajwade sirHon. Principal Prof. D. V. Rajwade sir,,
whose discipline has created regularity in us, so as to complete the project
within the given time.
Last but not the least; I am thankful to Mr. S. M. GanorkarMr. S. M. Ganorkar for his help in
this project work.
Contents
Introduction
Specifications of IC 74C926
Circuit diagram
Working of the circuit
Costing of the circuit
Part list
Bibliography
Introduction
The statisticians use special formulae to calculate the approximate
number of people coming to and going out of a place in a given time. But
none of these formulae can give 100% accurate and precise results. It is
impossible to manually count the same. But now using modern object
counter circuit, it is possible to count the same with 100% accuracy.
The circuit has one sensor fitted (at the waist-level) on the entry
door. It consists of a light beam propagated on the LDR circuit. So long as
the LDR is lighted, its resistance is LOW and the circuit remains silent.
But when the light beam is cut by an entering person, the resistance
of the LDR increases and a single clock pulse is fed to the input of the
circuit to advance the count by 1–digit.
The circuit described here, is meant to do just the very same thing.
The circuit can count up to 9999 entering or leaving persons or counts.
However, it can be used to count the number of articles passing on
conveyor belt (in an industry) etc.
The unit has unlimited applications in almost all fields of
industrialization. The counting capability of the circuit can be increased to
ten million (10,00000) or even greater. The complete circuit is based on
CMOS multiplexing LSI (Large Scale Integration) chip. Hence, it offers
reliability at a relatively low cost.
Specifications of IC 74C926
The MM74C925, MM74C926, MM74C927 and MM74C928 CMOS
counters consist of a 4-digit counter, an internal output latch, NPN output
sourcing drivers for a 7-segment display, and an internal multiplexing
circuitry with four multiplexing outputs. The multiplexing circuit has its own
free-running oscillator, and requires no external clock. The counters
advance on negative edge of clock. A HIGH signal on the Reset input will
reset the counter to zero, and reset the carryout LOW. A LOW signal on
the Latch Enable input will latch the number in the counters into the
internal output latches. A HIGH signal on Display Select input will select
the number in the counter to be displayed; a LOW-level signal on the
Display Select will select the number in the output latch to be displayed.
The MM74C925 is a 4-decade counter and has Latch Enable, Clock and
Reset inputs. The MM74C926 is like the MM74C925 except that it has a
display select and a carryout used for cascading counters. The carryout
signal goes HIGH at 6000, goes back LOW at 0000. The MM74C927 is
like the MM74C926 except the second most significant digit divides by 6
rather than 10. Thus, if the clock input frequency is 10 Hz, the display
would read tenths of seconds and minutes (i.e., 9:59.9). The MM74C928
is like the MM74C926 except the most significant digit divides by 2 rather
than 10 and the carry-out is an overflow indicator which is HIGH at 2000,
and it goes back LOW only when the counter is reset. Thus, this is a 3½
digit counter.
Features
Wide supply voltage range: 3V to 6V
Guaranteed noise margin: 1V
High noise immunity: 0.45 VCC (typical)
High segment sourcing current: 40 mA
@ VCC - 1.6V, VCC = 5V
Internal multiplexing circuitry
Design Considerations
Segment resistors are desirable to minimize power dissipation and
chip heating. The DS75492 serves as a good digit driver when it is desired
to drive bright displays. When using this driver with a 5V supply at room
temperature, the display can be driven without segment resistors to full
illumination. The user must use caution in this mode however, to prevent
overheating of the device by using too high a supply voltage or by
operating at high ambient temperatures.
The input protection circuitry consists of a series resistor, and a
diode to ground. Thus, input signals exceeding +Vcc will not be clamped.
This input signal should not be allowed to exceed 15V.
Logic Diagrams –
MM 74C925 MM74C926, MM74C927, MM74C928
Functional Description
Reset — Asynchronous, active highDisplay Select — high, displays output of counterLow, displays output of latchLatch Enable — High, flow through condition
Low, latch condition Clock —Negative edge sensitiveSegment Output — Current sourcing with 40 mA @VOUT =VCC - 1.6V (typical) Also, sink capability = 2 LTTL loadsDigit Output — Current sourcing with 1 mA @VOUT = 1.75VAlso, sink capability = 2 LTTL loadsCarry-Out — 2 LTTL loads
Characteristics
VIN(1) Logical “1” Input Voltage VCC = 5V 3.5 VVIN(0) Logical “0” Input Voltage VCC = 5V 1.5 VVOUT(1) Logical “1” Output Voltage VCC = 5V, IO = -10 mA(Carry-Out and Digit Output 4.5 V Only)VOUT(0) Logical “0” Output Voltage VCC = 5V, IO = 10 mA 0.5 V
IIN(1) Logical “1” Input Current VCC = 5V, VIN = 15V 0.005 1 mAIIN(0) Logical “0” Input Current VCC = 5V, VIN = 0V -1 -0.005 mAICC Supply Current VCC = 5V, Outputs Open Circuit, 20 1000 mAAt VIN = 0V or 5V
CMOS/LPTTL INTERFACEVIN(1) Logical “1” Input Voltage VCC = 4.75V VCC - 2 VVIN(0) Logical “0” Input Voltage VCC = 4.75V 0.8 VVOUT(1) Logical “1” Output Voltage VCC = 4.75V,(Carry-Out and Digit IO = -360 mA 2.4 VOutput Only)VOUT(0) Logical “0” Output Voltage VCC = 4.75V, IO = 360 mA 0.4 V
OUTPUT DRIVEVOUT Output Voltage (Segment IOUT = -65 mA, VCC = 5V, Tj = 25°C VCC - 2 VCC - 1.3 V
Sourcing Output) IOUT = -40 mA, VCC = 5V Tj = 100°C VCC - 1.6 VCC - 1.2 VTj = 150°C VCC - 2 VCC - 1.4 V
RON Output Resistance (Segment IOUT = -65 mA, VCC = 5V, Tj = 25°C 20 32WSourcing Output) IOUT = -40 mA, VCC = 5V Tj = 100°C 30 40 WTj = 150°C 35 50 Wave
Output Resistance (Segment 0.6 0.8 %/°C Output) Temperature CoefficientISOURCE Output Source Current VCC = 4.75V, VOUT = 1.75V, Tj = 150°C -1 -2 mA(Digit Output)
ISOURCE Output Source Current VCC = 5V, VOUT = 0V, Tj = 25°C -1.75 -3.3 mA(Carry-Out)
ISINK Output Sink Current VCC = 5V, VOUT = VCC, Tj = 25°C 1.75 3.6 mA(All Outputs)
Thermal Resistance MM74C925: (Note 2) 75 100 °C/WMM74C926, MM74C927, MM74C928 70 90 °C/W
Characteristics (contd)
Typical segment current Vs output voltage characteristics
Maximum power dissipation Vs ambient temperature
Average segment current Vs segment resistor value
Connecting the output
Segment output driver Input protection
Common cathode LED display
Segment identification diagram
Switching Time Waveforms
Input waveforms
Multiplexing output waveforms
Waveforms at the carry out pin
Pin configuration & dimensions
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” WidePackage Number N16E
(All dimensions are in inches/mm)
Physical Dimensions –
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” WidePackage Number N16E
(All dimensions are in inches/mm)
Physical Dimensions (Contd.) –
16-Lead Plastic Dual-In-Line Package (PDIP), JEDEC MS-001, 0.300” WidePackage Number N16E
(All dimensions are in inches/mm)
Absolute Maximum Ratings –
Note 1: “Absolute Maximum Ratings” are those values beyond which thesafety of the device cannot be guaranteed. Except for “Operating TemperatureRange” they are not meant to imply that the devices should be operatedat these limits. The Electrical Characteristics table provides conditionsfor actual device operation.
DC Electrical Characteristics –
Min/Max limits apply at –40°C £ jA +85°C, unless otherwise notedNote 2: jA measured in free-air with device soldered into printed circuit board.Voltage at Any Output Pin GND - 0.3V to VCC + 0.3VVoltage at Any Input Pin GND - 0.3V to +15VOperating TemperatureRange (TA) –40°C to +85°CStorage TemperatureRange –65°C to +150°CPower Dissipation (PD) Refer to PD(MAX) vs TA GraphOperating VCC Range 3V to 6VVCC 6.5VLead Temperature (Soldering, 10 seconds) 260°C
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Life Support Policy
As used herein:
Life support devices or systems are devices or systems, which –
a) Are intended for surgical implant into the body.
b) Support or sustain life.
c) And whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user.
d) A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS
CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS
WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT
OF FAIRCHILD SEMICONDUCTOR CORPORATION.
Published in the interest of mankind
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Pin Diagram of IC 74C926
Pin diagram & identification of pins – IC 74C926
Pin diagram & identification of pins – IC 555
Circuit Diagram
Sensor (The LDR)
Light Dependant Resistor – it is a passive light transducer. It is also
called as photoconductive cell because its conductivity changes due to
change in light intensity.
Basic Principle – when light falls on it its resistance decreases and when
it is dark, its resistance is maximum. The change in resistance is directly
proportional to intensity of light falling on it.
Construction – it is made up of photosensitive material like cadmium
sulphide (CdS), Selenium (Se), Cadmium Selenide (CdSe) or Lead
Sulphide (PbS). It is deposited on insulating surface like ceramic substrate
in the form of zigzag wire as shown in following figure. It is enclosed in
round metallic or plastic case and two electrodes are taken out for
external connections. The structure is covered with glass sheet to protect
it from moisture and dust and allows only light to fall on it.
Constructional diagram of LDR
Applications – 1. It is used in burglar alarm to give alarming sound when a burglar
invades sensitive premises.2. It is used in street light control to switch on the lights during dusk
(evening) and switch off during dawn (morning) automatically.3. It is used in Lux meter to measure intensity of light in Lux.4. It is used in photosensitive relay circuit.5. It is used in object counter circuit.
Costing of the Project
The costing of components, used in this project is as follows –
Sr.
Nos.
Particulars of
Component
Approximate
Cost
The prices given here are according to the bill-receipt obtained from
the shopkeeper. The above said material was purchased on / /
2004. And the material was purchased from ________ market.
Signature of the student
Parts List
IC 555 timer IC 1 no.
IC 74C926 multiplexing counter 1 no.
Display LT 543 4 nos.
Transistor BC 147 4 nos.
Resistors
Capacitors
Variable resistors
LDR Philips (Holland)
Bulb, p.c.b., IC sockets, connecting wires,
Suitable cabinet, soldering iron, etc.
Bibliography
Digital Electronic Principals :
By M. C. Sharma
Business Promotion Bureau, New Delhi
Principles of electronics :
By V. K. Mehta
EEE (Eastern Economy Edition)
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