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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